NONRESIDENTTRAININGCOURSE

Gas Turbine SystemsTechnician (Electrical) 3/GasTurbine Systems Technician(Mechanical) 3, Volume 1NAVEDTRA 14113

DISTRIBUTION STATEMENT A: Approved for public release; distribution is unlimited.

SUMMARY OFGAS TURBINE SYSTEMS TECHNICIAN

(ELECTRICAL) 3/GAS TURBINE SYSTEMSTECHNICIAN (MECHANICAL) 3

TRAINING MANUALS

VOLUME 1

Gas Turbine Systems Technician (Electrical) 3/Gas Turbine Systems Technician(Mechanical) 3, Volume 1, NAVEDTRA 14113, covers information on theratings, administration and programs, tools and test equipment, electricaltheory and mechanical theory, piping systems and their components, supportand auxiliary equipment, the power train, the controllable pitch system, andengineering electrical systems and their maintenance procedures.

VOLUME 2

Gas Turbine Systems Technician (Electrical) 3/Gas Turbine SystemsTechnician (Mechanical) 3, Volume 2, NAVEDTRA 14114, containsinformation on the basic fundamentals of gas turbines, the LM2500 gasturbine, the Allison 501-K17 gas turbine generator, engineering systems, electricplant operation, and the control consoles for the CG-, DD-, DDG-, andFFG-class ships.

PREFACE

By enrolling in this self-study course, you have demonstrated a desire to improve yourself and the Navy.Remember, however, this self-study course is only one part of the total Navy training program. Practicalexperience, schools, selected reading, and your desire to succeed are also necessary to successfully roundout a fully meaningful training program.

COURSE OVERVIEW: This course is designed to assist enlisted personnel in the advancement to GSEThird Class Petty Officer/GSM Third Class Petty Officer. In completing this course you will demonstrate aknowledge of course materials by correctly answering questions on the following topics: the requirementsfor advancement to GSE3 and GSM3; programs and record keeping procedures needed for the safeoperation of the main propulsion systems and the auxiliary equipment aboard ship; proper use of varioustools, test equipment, and indicating instruments used aboard gas turbine ships; basic concepts of electricaltheory, mechanical theory, and scientific principles applicable to gas turbine engines; the operation andcomponents of auxiliary equipment, including valves and piping system components, main reduction gearsand controllable pitch propeller systems, fuel and lube oil systems, associated pumps, and waste heat boilersystems; and basic troubleshooting methods, minor repairs, and test on motors, controllers, andswitchboards.

THE COURSE: This self-study course is organized into subject matter areas, each containing learningobjectives to help you determine what you should learn along with text and illustrations to help youunderstand the information. The subject matter reflects day-to-day requirements and experiences ofpersonnel in the rating or skill area. It also reflects guidance provided by Enlisted Community Managers(ECMs) and other senior personnel, technical references, instructions, etc., and either the occupational ornaval standards, which are listed in the Manual of Navy Enlisted Manpower Personnel Classificationsand Occupational Standards, NAVPERS 18068.

THE QUESTIONS: The questions that appear in this course are designed to help you understand thematerial in the text.

VALUE: In completing this course, you will improve your military and professional knowledge.Importantly, it can also help you study for the Navy-wide advancement in rate examination. If you arestudying and discover a reference in the text to another publication for further information, look it up.

1989 Edition Prepared byGSCS Bradford E. Edwards and

GSEC Edward E. Ragsdale

Published byNAVAL EDUCATION AND TRAINING

PROFESSIONAL DEVELOPMENTAND TECHNOLOGY CENTER

NAVSUP Logistics Tracking Number0504-LP-026-7790

CONTENTS

CHAPTER

1. Rating Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

2. Administration and Programs . . . . . . . . . . . . . . . . . . . . . .

3. Tools and Test Equipment. . . . . . . . . . . . . . . . . . . . . . . . .

4. Electrical Theory and Mechanical Theory. . . . . . . . . . . .

5. Indicating Instruments . . . . . . . . . . . . . . . . . . . . . . . . . . . .

6. Piping System Components . . . . . . . . . . . . . . . . . . . . . . . .

7. Engineering Support and Auxiliary Equipment . . . . . . .

8. Power Train and Controllable Pitch Propeller . . . . . . .

9. Engineering Electrical Equipment . . . . . . . . . . . . . . . . . . .

10. Engineering Electrical Equipment Maintenance . . . . . . .

APPENDIX

I. Glossary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

II. Abbreviations and Acronyms . . . . . . . . . . . . . . . . . . . . . .

III. Electrical Symbols . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

IV. Piping Print Symbols . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

V. Metric System. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

VI. List of Navy Electricity and Electronics TrainingSeries . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Page

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3-1

4-1

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7-1

8-1

9-1

10-1

AI-1

AII-1

AIII-1

AIV-1

AV-1

AVI-1

INDEX . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . INDEX-1

The purpose of this manual is to provide youwith the basic foundation of information you needas you continue to advance in the Navy. Afterreading this manual, you should be able torecognize the increased responsibility needed foradvancement and to identify the other sources ofinformation available to you. As you attain eachpromotional level in your chosen rating, you, aswell as the Navy, will benefit. The Navy willbenefit and you will continue to do so as youbecome more adept at the technical aspects ofyour rating. With each advancement, you acceptan increasing responsibility in military andoccupational matters.

You will find that your responsibilities formilitary leadership are the same as those of pettyofficers in other ratings. Every petty officer is amilitary person as well as a technical specialist.However, your responsibilities for technicalleadership are special to your rating. They aredirectly related to the nature of your work.Operating and maintaining the ship’s engineeringsystems and equipment is a job of vitalimportance, and it requires teamwork.

Before you study this book, we recommendthat you complete or at least review the followingNavy courses:

Navy Electricity and Electronics TrainingSeries (NEETS), Modules 1, 2, 3, 4, 5, 16,and 21.

The NEETS was developed for use bypersonnel in many electrical- and electronic-related Navy ratings. Written by, and with theadvice of, senior technicians in these ratings, thisseries provides beginners with fundamentalelectrical and electronic concepts through themedium of self-study. The presentation is notoriented to any specific rating structure. Thisseries is divided into 22 modules that containrelated information organized in traditional pathsof instruction. Module 1 introduces you to thecourse with a short history of electricity and

electronics and proceeds into the characteristicsof matter, energy, and direct current. Module 1also describes some of the general safety pre-cautions and first-aid procedures that should becommon knowledge for a person working in thefield of electricity. Related safety hints are locatedthroughout the rest of the series. Modules 2through 5 deal with the generation of electricity;the application of resistors, capacitors, andinductors; and the phenomena of alternatingcurrent. Module 16 introduces the beginner tosome of the more commonly used pieces of testequipment and their applications. Module 21introduces you to alternative methods ofperforming electronics measurements.

As you progress up the ladder of advance-ment, and to further your knowledge of electricityand electronics, we recommend you becomefamiliar with the remaining 15 modules of thisseries.

Basic Machines, NAVPERS 10624

Basic Machines was written as a reference forthe enlisted person in the Navy whose dutiesrequire knowledge of the fundamentals ofmachinery. It begins with the simplest of machines(the lever), then proceeds with a discussion ofother types of machines-the block and tackle,wheel and axle, inclined plane, and screw andgear. It explains the concepts of work and power,and differentiates between the terms force andpressure. The fundamentals of hydrostatic andhydraulic mechanisms are discussed in detail. Thefinal chapters of the book include severalexamples of the combinations of simplemechanisms to make complex machines.

Use and Care of Hand Tools and Measuring Tools, NAVEDTRA 12085

This training manual (TRAMAN) was writtento aid in the maintenance effort. It providesdescriptions, general uses, correct operation, andapproved maintenance procedures for those hand

INTRODUCTION

tools and power tools commonly used in theNavy. It stresses the importance of good work-manship. Also, by emphasizing good safetypractices, it aids in the prevention and minimiz-ing of personnel and equipment damage.

To help you study any book, you shouldbecome acquainted with its design. Here are somethings you should know about this TRAMAN andits associated nonresident training course (NRTC).

This TRAMAN is designed to help youfulfill professional requirements for advancementto GSE3 and GSM3. The manual was preparedusing the GSE3 and GSM3 occupationalstandards (OCCSTDs) prescribed by the Chief ofNaval Personnel in the Manual of Navy EnlistedManpower and Personnel Classifications andOccupational Standards, NAVPERS 18068(VOLUME 1). This manual contains the informationneeded to establish a good foundation for bothGSEs and GSMs.

The Personnel Qualification Standards(PQS) and OCCSTDs for the GSE3 and GSM3ratings are very similar; therefore, it was moreeconomical to develop a single TRAMAN. Wewish to emphasize that the two ratings areseparate. In writing one TRAMAN, we absolutelydo not intend to infer that the ratings should becompressed at the third class petty officer level.

This GSE3/GSM3 TRAMAN is written tothe OCCSTDs, personnel advancement require-ments (PARS), and PQS of the various watchstations of both ratings. Chapter 10 of thisTRAMAN is unique to the GSEs.

You must satisfactorily complete thisTRAMAN before you can advance to GSE3 or

GSM3. This is true whether you are in the regularNavy or in the Naval Reserves. However, thosepersonnel who satifactorily complete Gas TurbineA School may have this course waived by the localcommand.

This TRAMAN is written to provide youa basic foundation of information that you willuse throughout your naval career as a GSE orGSM. You will find additional information andterminology for your rating in the followingappendixes:

Appendix I-a glossary of terms peculiar tothe GS ratings. Use it whenever you are not sureof the meaning of a word.

Appendix II–a list of abbreviations andaccronyms used throughout this TRAMAN.

Appendix III–electrical and electronicsymbols.

Appendix IV–piping print symbols.

Appendix V–metric system.

Appendix VI–list of the NEETS modules.

Appendix VII–list of reference materialsused to prepare this TRAMAN.

Information can be organized and presentedin many different ways. Before you study thechapters in this book, read the table of contentsand note the arrangement of information in thisTRAMAN. You will find it helpful to get anoverall view of the organization of this TRAMANbefore you start to study it.

CHAPTER 1

RATING INFORMATION

This training manual is designed to help youincrease your knowledge in the various aspects ofthe Gas Turbine Systems Technician ratings. Itwill help you prepare for advancement to thirdclass petty officer. Your contribution to the Navydepends on your willingness and ability to acceptincreasing responsibilities as you advance in rate.When you assume the duties of a Gas TurbineSystems Technician (Electrical) (GSE) or a GasTurbine Systems Technician (Mechanical) (GSM),you begin to accept certain responsibilities for thework of others. As you advance in your career,you accept additional responsibilities in militarysubjects as well as occupational and trainingrequirements for the GSE or GSM rating.

After studying this chapter, you should be ableto describe the GSE/GSM ratings in terms of theirhistory and present status, to identify the dutiesand responsibilities of GSEs and GSMs, tosummarize the advancement requirements forGSEs and GSMs, and to list the general trainingsources available for you.

FORMATION OF THEGSE/GSM RATINGS

In late 1975, with the commissioning of theUSS Spruance (DD-963), the Navy realized therewas a need for the formation of a specialized gasturbine rating. At that time, personnel drawnprimarily from the Electrician’s Mate (EM),Engineman (EN), and Interior CommunicationsElectrician (IC) ratings were being put throughspecial gas turbine pipeline training for dutyaboard the new gas turbine ships. Then, in 1978the decision was made to form the GSE and GSMratings. On October 1, 1978, both ratings wereput into effect. All EMs, ENs, and ICs withDD-963 class Naval Enlisted Classification Codes(NECs) were converted to GSE or GSM, asapplicable. Then, with the introduction of theOliver Hazard Perry (FFG-7) to the fleet,more schools and NECs were required to train

personnel properly to maintain and to operatethese ships.

DUTIES AND RESPONSIBILITIES

A third class GSE or GSM has the opportunityto work with a wide variety of main propulsion,auxiliary, and electrical equipment. The GSE isprimarily responsible for the electronic controlcircuitry interfaces, such as signal conditioners,control consoles, and designated electrical equip-ment associated with shipboard propulsion andelectrical power generating plants. The GSM isprimarily responsible for the operation andmaintenance of the gas turbine engines (GTEs),gas turbine generators (GTGs), reduction gears,and associated equipment (such as pumps, valves,oil purifiers, heat exchangers, shafts, and shaftbearings). As you continue to advance in theNavy, as a GSE or GSM you will increasinglycross-train between GSE and GSM. This willprepare you for more demanding assignments.

We have arranged the GSE3/GSM3 Volumes1 and 2 manuals to give you a systematicunderstanding of your job. The occupationalstandards (OCCSTDs) used in preparation of thetraining manuals are contained in the Manualof Navy Enlisted Manpower and PersonnelClassifications and Occupational Standards,NAVPERS 18068. We recommend that youstudy the GSE and GSM sections of NAV-PERS 18068E to gain an understanding of theskills required of a GSE/GSM. Then study thesubject matter carefully. The knowledge you gainwill enable you to become a more proficienttechnician, and you and the Navy will profit fromyour skills.

ADVANCEMENT REQUIREMENTS

The office of the Chief of Naval Operationsmonitors current and future vacancies in the

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Navy. These vacancies are changed to quotas foreach rate in all Navy ratings. Quotas are used todetermine the number of selectees for advance-ment in each advancement cycle.

Your ability to fill one of the quotas in yourrating depends on how well you know and do yourjob and on your desire and readiness for advance-ment. The Navy provides you with challengingwork and training that helps you learn more aboutyour job. Your seniors are interested in seeing youadvance. They provide feedback to you throughpersonal contact and performance evaluations.The rest is up to you.

ELIGIBILITY REQUIREMENTSFOR ADVANCEMENT

You must complete several steps to be-ome eligible for advancement. These stepsinclude completing the time requirements, Per-sonnel Advancement Requirements (PARs), andmilitary required courses and tests; receiving arecommendation by your commanding officer;meeting physical readiness/body fat standards;completing required professional performancecourses; and passing the advancement-in-rateexamination. For more specific information onyour eligibility, contact your educational servicesofficer (ESO).

PROFESSIONAL DEVELOPMENT

Two of the most important aspects of yourprofessional development are SUSTAINEDSUPERIOR PERFORMANCE and STUDYINGFOR ADVANCEMENT. How you do your jobdetermines how you are evaluated. To achieve anevaluation of sustained superior performance, youmust demonstrate a continual outstanding jobperformance in all areas of your rate. Yourexam performance, rating knowledge, and workperformance demonstrate the extent of yourstudying.

Sustained Superior Performance

Your key to success in the Navy is a sustainedsuperior performance. You can be a topperformer among your peers by reaching for yourfull potential. Remember, the higher youradvancement goal, the stiffer the competition.Your performance evaluations must show thatyou are among the best in the Navy, not just atyour present command. The Navy wants andpromotes people with a record of doing the job

well. That means doing the job well on shore orat sea. Your performance is reported in yourperformance evaluation. Let’s look at evaluationsto see their impact on advancement.

PERFORMANCE EVALUATIONS.—YourENLISTED PERFORMANCE EVALUATIONREPORT is the most significant management toolin your service record. It is one of the firstdocuments used by your superiors to makeadvancement decisions about you because it is acontinuous record of your performance. You caninfluence what goes into your evaluation byhaving sustained superior performance. In plainwords, always do top-notch work.

PERFORMANCE MARK AVERAGEFACTOR.—The average of your performanceevaluation marks are converted to a performancemark average (PMA). This is one of the moreimportant factors used to compute your finalmultiple score (FMS). Three factors are usedin the figuring of your FMS–experience,performance, and exam score. Your FMS isused to rank-order you against all other candidateswho take the same exam as you. To give you someidea of the impact your performance has on yourFMS (and your chances for advancement), lookat the following figures: If you are a candidatefor PO3 or PO2, 30 percent of your FMS is basedon your performance; if you are a PO1 candidate,the percentage is 35 percent; for CPO, it is 40percent.

Studying for Advancement

Closely related to your ability to perform ina superior manner is the amount and quality ofstudying you do. An advancement handbook(Advancement Handbook for Petty Officers, GasTurbine Systems Technician (GS), NAVED-TRA 71065) is available to help you prepare andstudy for advancement. A handbook exists forevery rating in the Navy. Each handbook isdivided into three parts. The first part explainsthe Navy Advancement System; the second partcontains the naval standards (NAVSTDs) withtheir supporting bibliography; the third partcontains the OCCSTDs with their supportingbibliography and the PARs. Your rating hand-book shows you what courses are mandatoryrequirements for advancement.

You should concentrate on three major areasof study, (1) information particular to your job

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and command responsibilities, (2) NAVSTDs, and(3) OCCSTDs.

NAVAL STANDARDS.—The NAVSTDsdescribe knowledge and abilities required of everyenlisted person in the Navy. The NAVSTDs arecumulative; that is, as you advance in paygrade,you are responsible for NAVSTDs in the paygradeyou are trying for, your present paygrade, andall paygrades below. You are tested on yourknowledge of NAVSTDs by the military/leader-ship exams for PO3 through CPO as part of youreligibility requirements.

OCCUPATIONAL STANDARDS.—TheOCCSTDs are standards that express the Navy’sminimum requirements for enlisted occupationalskills established by manpower and personnelmanagers. The OCCSTDs are written as taskstatements. They form the foundation of a wellplanned system that dovetails your training,advancement, and job assignments. Besidesprescribing tasks expected of you, OCCSTDs alsoindicate general paygrade responsibility levels. Forexample, OCCSTD 37012, Maintain Tools, is aroutine task that is located at a lower paygrade;more difficult tasks, such as OCCSTD 37049,Supervise Engine Changeouts, are located at ahigher paygrade. The OCCSTDs, like theNAVSTDs, are cumulative. That means as youadvance in your rating, you are responsible forthe OCCSTDs of the rate you are trying for, yourpresent rate, and all lower rates.

BIBLIOGRAPHIES FOR NAVSTDS ANDOCCSTDS.—You can find supportingbibliographies for NAVSTDs and OCCSTDs ineither of two publications, the AdvancementHandbook for Pet ty Of f icers and theBibliography for Advancement Study, NAVED-TRA 10052 (current edition). The bibliographiesin both of these publications contain the samereferences.

EXAM AND NOTIFICATIONOF RESULTS

The exam is a 150-question test that you willhave up to 3 hours to take. After completing theexam, you will be given the SUBJECT-MATTERSECTION IDENTIFICATION SHEET (fig. 1-1).This is sometimes called the “tear-off sheet.”Keep this sheet. When you receive yourEXAMINATION PROFILE INFORMATIONFORM (fig. 1-2), you can look at the section of

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the text that you need to work on because of lowscores. The Subject-Matter Section Identificationsheet has three columns. The first column showsthe number of sections in the exam, the secondcolumn gives you the title of the sections, and thethird column shows the OCCSTDs that werecovered in that section. The Examination ProfileInformation form that you will receive when theexam results arrive at your command shows theexamination section and your standing in thatsection compared to all others who took the sameexam. The section number corresponds with theExamination Section column on the Subject-Matter Section Identification sheet. Use thisinformation to discover the knowledge, strengths,and weaknesses that you were tested on in thisexam only. By looking at the Advancement Hand-book for Petty Officer, you will find thereferences used in making up that section of theexam.

TRAINING SOURCES

The Navy provides various types of training.In this section we are going to discuss some ofthe different types of training and the differentsources you can use in locating available training.

SCHOOLS

The Navy provides three major types ofschools to assist its personnel. The different typesof schools are (1) the technical training schools,(2) Naval Leadership Development Program(NLDP) school , and (3) f i re- f ight ingand damage control schools.

Technical Schools

The main school for gas turbine personnel isin Great Lakes, Illinois. The GSE/GSM “A”schools and the GSE/GSM “C” schools arelocated there; however, the Navy has othertechnical schools on both coasts that will assistpersonnel in their job. For more informationabout these other schools, you should talk to yourdivisional training petty officer.

Naval Leadership Development ProgramSchool

As you advance to third class petty officer,your responsibilities for military leadership willbe about the same as those of petty officers in

Figure 1-1.—Subject-Matter Section Identification sheet.

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Figure 1-2.—Examination Profile Information form.

other ratings. (All petty officers have military aswell as technical duties.) Operating and maintain-ing a ship’s engineering plant and associatedequipment requires teamwork along with a specialkind of leadership ability that can only bedeveloped by personnel who have a high degreeof technical competence and a deep sense ofpersonal responsibility. Strive to improve yourleadership ability and technical knowledgethrough study, observation, and practicalapplication.

Technical leadership involves more than justgiving orders. In fact, you can demonstrate someof the most important aspects of technical leader-ship even if you are not directly supervising otherpersonnel. As a GSE or GSM, you demonstratetechnical leadership when you follow ordersexactly, when you follow safety precautions, andwhen you accept responsibility. Also, when youcontinue to increase your professional knowledgeand when you perform every detail of your workwith integrity and reliability, you improve yourtechnical leadership know-how.

Another way in which to gain additionalleadership skills is through attendance at theNaval Leadership Development Program(NLDP) school. All petty officers shouldattend this school to fine tune the leadership skillsthey have attained through study, observation,and application.

Fire-Fighting and Damage Control Schools

At various times throughout your Navy career,you may also attend various fire-fighting anddamage control schools. There can NEVER beenough emphasis placed on the importance ofdamage control aboard ship. You will find thatdamage control and fire drills will be heldroutinely in port, at sea, and during special fleetexercises or refresher training. You must learnyour duties for damage control emergencies to thevery best of your ability because your life and thelives of your shipmates may depend on youractions.

TRAINING MANUALS

There are two general types of trainingmanuals (TRAMANs). RATING manuals (suchas this one) are prepared for most enlisted ratings.A rating manual gives information directly relatedto the OCCSTDs of one rating. SUBJECTMATTER manuals or BASIC manuals giveinformation that applies to more than one rating.

Training manuals are revised to keep them up-to-date technically. The revision of a rate train-ing manual is identified by a letter following theNAVEDTRA number. You can tell whether anyparticular copy of a training manual is the latestedition by checking the NAVEDTRA number andthe letter following this number in the mostrecent edition of the List of Training Manuals and

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Correspondence Courses, NAVEDTRA 10061.(NAVEDTRA 10061 is actually a catalog that listsall current training manuals and courses; you willfind this catalog useful in planning your studyprogram.)

Each time a TRAMAN is revised, it is broughtinto conformance with the official publicationsand directives on which it is based. However,during the life of any edition of a TRAMAN,changes are made to the official sources anddiscrepancies arise. In the performance of yourduties, you should always refer to the appropriateofficial publication or directive. If the officialsource is listed in Bibliography for AdvancementStudy, NAVEDTRA 10052, the Naval Educationand Training Program Management SupportActivity (NETPMSA) uses it as a source inpreparing the fleetwide examinations for advance-ment. In case of a discrepancy between anypublications listed in NAVEDTRA 10052 for agiven rate, the examination writers use the mostrecent material.

Training manuals are designed to help youprepare for advancement. The following sugges-tions may help you make the best use of thismanual and other Navy training publicationswhen you prepare for advancement.

1. Study the NAVSTDs and the OCCSTDsfor your rating before you study the trainingmanual and refer to the standards frequently asyou study. Remember, you are studying themanual primarily to meet these standards.

2. Set up a regular study plan. It will probablybe easier for you to stick to a schedule if you canplan to study at the same time each day. Ifpossible, schedule your studying for a time of daywhen you do not have many interruptions ordistractions.

3. Before you begin to study any part of themanual intensively, become familiar with theentire book. Read the preface and the table ofcontents. Check through the index. Thumbthrough the book without any particular plan.Look at the illustrations and read bits here andthere as you see things that interest you. Reviewthe glossary. It provides definitions that apply towords or terms as they are used within theengineering field and within the text. There aremany words with more than one meaning. Do not

assume that you know the meaning of a word!As you study, if you cannot recall the useof a word, look it up in the glossary. Foryour convenience, a list of abbreviationsand a table on conversion to the metricsystem appear as appendixes in the back of thismanual.

4. Look at the training manual in more detailto see how it is arranged. Look at the table ofcontents again. Then, chapter by chapter, readthe introduction, the headings, and the sub-headings. In this manner you will get a pretty clearpicture of the scope and content of the book. Asyou look through the book, ask yourself somequestions.

What do I need to learn about this?

What do I already know about this?

How is this information related toinformation given in other chapters?

How is this information related to theOCCSTDs?

EDUCATIONAL GUIDANCE

Numerous personnel are available aboard shipwho can assist you in furthering your Navyeducation.

Divisional Training Petty Officer

Your divisional training petty officer canhelp you with any questions you may haveabout where to obtain study material. Thetraining petty officer usually issues you yourPQS material and maintains the associatedprogress chart.

Educational Services Officer

The ESO maintains the TRAMANs, non-resident training courses (NRTCs), arid NRTCanswer sheets. The ESO can also assist you withoff-duty education such as the Scholastic AptitudeTest (SAT) and the College Level Examination

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Program (CLEP) tests, as well as enrollment inlocal colleges.

Command Career Counselor

The command career counselor can assistyou in applying for schools, arranging forduty stations in conjunction with GUARDreenlistments, and any other questions you mayhave about your career path.

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SUMMARY

This chapter has covered information of therating, duties and responsibilities, advancementrequirements, and training sources. All these areasare important in their own right. If you wish toadvance in the Navy, you should study theOCCSTDs and the publications mentioned in theAdvancement Handbook for Petty Officers.

CHAPTER 2

ADMINISTRATION AND PROGRAMS

As you progress up the ladder of advance-ment, you will be required to become more andmore involved with the administrative portion ofyour rates. Administration is the machinery bywhich an organization plans and accomplishes itsassigned responsibilities. Experience hasdemonstrated that the issuance of procedures inwriting fosters the use of the best availabletechniques for administration. Additionally, itprovides for uniformity of operations in light ofthe continuing turnover of personnel within theGSE/GSM ratings.

The Navy has many programs that will affectyou at some time in your Navy career. In thischapter you will learn the basics of some of theprograms that will affect you as a GSE or GSM.This chapter is not designed to make you anexpert in any of these programs, rather it willmake you aware of their existence and adviseyou where to seek more in-depth information.Programs we discuss include only those you willneed to know about while carrying out yourassigned duties.

After studying this chapter, you should be ableto identify and locate the publications, blueprints,catalogs, charts, directives, drawings, manuals,and schematics you will need to perform your day-to-day tasks. You should be able to describe theproper procedures for submitting work deferrals,completions, and maintenance data system forms.Also, you should be able to recognize the varioustypes of logs and records and explain how theyare maintained and why they are kept. You shouldbe able to discuss with some accuracy the variousprograms pertinent to you as an engineer (thatis, safety, equipment tag-out, personnel pro-tection, fluid management, physical security,environmental quality, gauge calibration, andvalve maintenance); understand how the Person-nel Qualifications Standards (PQS) program willmold you into a more competent watch stander;and discuss the function of the Main Space Fire

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Doctrine and how it interacts with the EngineeringOperational Sequencing System (EOSS).

SOURCES OF INFORMATION

One of the most useful things you can learnabout a subject is how to find out more about it.No single publication can give you all theinformation you need to perform the duties ofyour rating. You should learn where to look foraccurate, authoritative, up-to-date information onall subjects related to engineering administrationand engineering programs. In this section we willdiscuss most of the publications you willuse. These publications contain the detailedinformation you need for advancement and foreveryday work. Some are subject to change orrevision from time to time-some at regularintervals, others as the need arises. When usingany publication that is subject to change orrevision, be sure you have the latest edition. Whenusing any publication that is kept current bychanges, be sure you have a copy in which allofficial changes have been made. Studyingcanceled or obsolete information will not help youto do your work or to advance in rate. At best,it is a waste of time; at worst, it may bedangerously misleading.

NAVAL SEA SYSTEMS COMMANDPUBLICATIONS

The publications issued by the Naval SeaSystems Command (NAVSEA) are of particularimportance to engineering department personnel.They disseminate authoritative informationconcerning equipment operation and technicalor safety matters requiring immediate fleetimplementation. They also provide the status ofselected technical/logistic issues for the variousclasses of ships. Although you do not need toknow everything in these publications, you shouldhave a general idea of their content.

The Naval Ships’ Technical Manual (NSTM)is the basic engineering doctrine publication ofNAVSEA. NAVSEA keeps the manual up-to-dateby quarterly changes. When NAVSEA issues newor revised chapters, they designate them with anew chapter numbering system.

The following chapters of the Naval Ships’Technical Manual are of particular importanceto GSEs and GSMs; they reflect the new and oldnumbers for each chapter.

NEW

078

220,Vol 2

221

234

241

OLD

(9950)

(9560)

(9416)

(9420)

243 (9430)

244 (9431)

245 (9440)

254 (9460)

255 (9562)

262 (9450)

300 (9600)

302 (9630)

491

503

504

505

541

(9690)

(9470)

(9870)

(9480)

(9550)

CHAPTER DRAWINGS

Gaskets, Packings, and Seals

Boiler Water/Feedwater - Testand Treatment

Boilers

Some of your work as a GSE/GSM willrequire you to read and work from mechanicaldrawings. You can find information on how toread and interpret drawings in Blueprint Readingand Sketching, NAVEDTRA 12014.

Marine Gas Turbines

Propulsion Reduction Gears,Couplings, and AssociatedComponents

Shafting, Bearings, and Seals

Bearings

Propellers

Condensers, Heat Exchangers,and Air Ejectors

Feedwater System and Ap-paratus

Lubricating Oils, Greases, andHydraulic Fluids and Lubrica-tion Systems

Electric Plant General

Besides knowing how to read drawings, youmust know how to locate applicable drawings. Forsome purposes, the drawings included in themanufacturers’ technical manuals for themachinery or equipment may give you theinformation you need. In many cases, however,you may have to consult the onboard drawings.The onboard drawings are sometimes referred toas ship’s plans or ship’s blueprints. An indexcalled the ship’s drawing index (SDI) lists the on-board drawings. The SDI lists all workingdrawings that have a NAVSHIPS drawingnumber, all manufacturers’ drawings designatedas certification data sheets, equipment drawinglists, and assembly drawings that list detaildrawings. The SDI identifies the onboarddrawings by an asterisk (*).

Electric Motors and Control-lers

Electric Measuring and TestInstruments

Pumps

Pressure, Temperature, andOther Mechanical and Elec-tromechanical Measuring In-struments

Drawings are listed in numerical order in theSDI. Onboard drawings are filed according tonumerical sequence. Two types of numberingsystems are in use for drawings with NAVSHIPSnumbers. The older system is an S-groupnumbering system. The newer system, used on allNAVSHIPS drawings since 1 January 1967,is a consolidated index numbering system. Across-reference list of S-group numbers andconsolidated index numbers is given in NAV-SHIPS Consolidated Index of Materials andServices Related to Construction and Conversion.

SHIPS’ MAINTENANCE ANDMATERIAL MANAGEMENT

(3-M) SYSTEMSPiping Systems

Ship Fuel and Fuel SystemsThe Ships’ Maintenance and Material Man-

agement (3-M) Manual, OPNAVINST 4790.4,describes in detail the Ships’ 3-M Systems. The

MANUFACTURERS' TECHNICALMANUALS

Another important source of information youcan use is the manufacturer’s technical manualfor the piece of equipment you are working on.These manuals contain all the informationnecessary for operation, troubleshooting,overhaul, and repair. For example, they containinformation on gas turbine engine (GTE)component change-out and engine change-out.

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primary objective of the Ships’ 3-M Systems isto provide for managing maintenance andmaintenance support in a way to ensure maximumequipment operational readiness. The Ships’ 3-MSystems is divided into two subsystems. They arethe Planned Maintenance System (PMS) and theMaintenance Data System (MDS).

PURPOSES OF PMS

The PMS was established for several purposes:

1. To reduce complex maintenance tosimplified procedures that are easily identified andmanaged at all levels

2. To define the minimum planned main-tenance required to schedule and control PMSperformances

3. To describe the methods and tools to beused

4. To provide for the detection and pre-vention of impending casualties

5. To forecast and plan manpower andmaterial requirements

6. To plan and schedule maintenance tasks7. To estimate and evaluate material readiness8. To detect areas requiring additional or

improved personnel training and/or improvedmaintenance techniques or attention

9. To provide increased readiness of the ship

BENEFITS OF PMS

The PMS is a tool of command. By usingPMS, the commanding officer can readilydetermine whether his ship is being properlymaintained. Reliability and availability areimproved. Preventive maintenance reduces theneed for major corrective maintenance, increaseseconomy, and saves the cost of repairs.

The PMS assures better records because theshipboard maintenance manager has more usefuldata. The flexibility of the system allows forprogramming of inevitable changes in employ-ment schedules. This helps to better planpreventive maintenance,

The PMS helps leadership and managementreduce frustrating breakdowns and irregular hoursof work, and thus improves morale. It enhancesthe effectiveness of all hands.

LIMITATIONS OF PMS

The PMS is not self-starting; it doesnot automatically produce good results. Itrequires considerable professional guidance andcontinuous direction at each level of the system’soperation. One individual must have both the

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authority and the responsibility at each level ofthe system’s operation.

Training in the maintenance steps as well asin the system is necessary. No system is asubstitute for the actual, technical ability requiredof the petty officers who direct and perform theupkeep of the equipment.

CURRENT SHIP’S MAINTENANCEPROJECT

The Current Ship’s Maintenance Project(CSMP) is a numerical listing of outstandingdeficiencies for all work centers aboard ship.Previously, an appropriate shore facility preparedand distributed the CSMP. However, because ofdeployment schedules and delays in mailing, theCSMP did not reflect the actual status ofcompleted actions. Now, with the introduction ofa 3-M computer system, most ships can prepareand update their own CSMP and deliver it on tapeto the appropriate shore facility.

As a third class petty officer, you prepareforms for deferred maintenance actions and/orwork requests. If a problem arises with a pieceof equipment that cannot be repaired within30 days, you must prepare a deferred action. Ifthe problem is beyond a ship’s force capabilityto repair, you have to prepare a deferredaction/work request. It is very important that youmaintain a timely and accurate account for trendanalysis so supervisors can organize effective workschedules.

Because of rapid changes in the Ships’ 3-MSystems, always refer to a current copy of theShips’ Maintenance and Material Management(3-M) Manual.

ENGINEERING ADMINISTRATION

In this section we will discuss the portions ofengineering administration pertinent to you as athird class GSE or GSM, such as the EngineeringDepartment Organization and RegulationsManual (EDORM), logs and records, programs,the Personnel Qualification Standards (PQS), theMain Space Fire Doctrine, and the EOSS.

EDORM

The EDORM is a joint type-commander in-struction (COMNAVSURFLANTINST 3540.18and COMNAVSURFPACINST 3540.14) that isusually modified by each ship to suit the ship’sspecial requirements. You should refer to itfor matters pertaining to the organization,

management, operation, and readiness of theengineering department.

STANDING/NIGHT ORDERS

The various operating orders that you mustbecome familiar with include standard (orstanding) orders, standing orders for specialevolutions, and night orders.

One of the commanding officer’s standing or-ders specifically pertaining to the engineering de-partment is the Restricted Maneuvering Doctrine.This is an instruction that is reviewed by each newcommanding officer and approved or revised tohis own requirements. It includes main enginecombinations, generator combinations, standbysetups, and casualty procedures to use during

Figure 2-1.—Engineering Log, NAVSEA 3120/2B.

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maneuvering in restricted waters or along-side another ship. The commanding officer’sRestricted Maneuvering Doctrine may alsoinclude instructions on casualty control pro-cedures during general quarters.

The engineer officer also has standingorders covering a wide variety of subjects.They include instructions for watch standers,reporting procedures for casualties, and logentries.

Another standing order, which is moreof a shipboard instruction, is the ship’sFire Doctrine. All personnel aboard shipneed to familiarize themselves with its con-tents. The Fire Doctrine contains all thebasic information necessary to know for report-ing, fighting, and extinguishing a shipboardfire.

Night orders have information on all propul-sion and auxiliary equipment in use, any expectedmajor speed changes, or changes to plant status.They include any special instructions the engineerofficer may have for the watch standers. Whenthe ship is underway, the engineer officer writesthe night orders and has them delivered to centralcontrol station (CCS) on the 2000 to 2400watch.

LOGS AND RECORDS

You will be required to maintain variousengineering logs and records. The EngineeringLog and the Engineer’s Bell Book or AutomaticBell Log are the only legal documents compiledby the engineering department. The EngineeringLog is a midnight-to-midnight record of the ship’sengineering department. The Engineer’s Bell Bookor Automatic Bell Log is a legal document of anyengine order regarding a change in the movementof the propeller(s). Any other logs and recordsthat you may be required to maintain, such asequipment operating logs, are not normallyconsidered legal documents.

Engineering Log

You will use the Engineering Log, NAVSEA3120/2B (fig. 2-l), and the Engineering Log-Continuation, NAVSEA 3120/2C (fig. 2-2), torecord important daily events and data pertain-ing to the engineering department and the opera-tion of the engineering plant. The log has spacesfor you to record equipment in operation; ship’sdraft and displacement; liquid load in gallons andpercent; the name of the ship, the date, and the

Figure 2-2.—Engineering Log-Continuation Sheet, NAVSEA 3120/2C.

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location or route of the ship; and remarks (2) in chapter 10 of U.S. Navy Regulations, (3)chronicling important events. in chapter 090 of Naval Ships’ Technical Manual,

Entries made in the Engineering Log must and (4) in directives from the type commander.follow instructions given (1) on the Engineering Remarks written in the Engineering LogLog-Instructions, NAVSEA 3120/2D (fig. 2-3), must include (1) personnel casualties (injuries),

Figure 2-3.—Engineering Log-Instructions, NAVSEA 3120/2D.

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(2) equipment casualties, (3) changes in equipmentstatus, (4) changing to or from maneuveringcombinations, and (5) such other matters asspecified by competent authority. You must writeeach entry at the time the event occurred. Usestandard Navy phraseology, and write eachentry as a complete statement.

Type commanders may increase the recordingrequirements. Instructions on these increasedrequirements will be published by writtendirectives from the type commanders.

The original Engineering Log, prepared neatlyin black ink or pencil, is the legal record. Theengineering officer of the watch (EOOW) (under

way) or the engineering duty officer (EDO) (inport) will prepare and sign the remarks. You maynot make erasures in the log. Make correctionswith a single line drawn through the original entryso that it remains legible. Then write the correctentry. Only the person required to sign the log forthat watch can make corrections, additions, orchanges, and that person must initial the marginof the page.

The engineer officer reviews the log daily forcompleteness and accuracy and signs it inthe space provided. The commanding officerapproves and signs the Engineering Log-TitlePage, NAVSEA 3120/2A (fig. 2-4), on the last

Figure 2-4.—Engineering Log-Title Page, NAVSEA 3120/2A.

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calendar day of each month and on the day herelinquishes command.

The ship maintains completed EngineeringLog sheets in a ring or post binder and retainsthem on board for 3 years. Personnel makingentries in the Engineering Log number the pagesconsecutively. A new series of page numberscommences on the first day of each month.

Engineer’s Bell Book

The Engineer’s Bell Book, NAVSHIPS3120/1, shown in figure 2-5, is a record of allorders received by the station in control of thethrottles regarding a change in the movement ofthe propellers. The throttle operator (or assistant)makes entries as soon as he receives an order. Anassistant may make entries when the ship is in aspecial maneuvering situation that may call for

numerous or rapid speed changes. This allows thethrottle operator to give complete attention toanswering the bells.

All entries made in the Engineer’s Bell Bookmust follow the Instructions for Keeping theEngineer’s Bell Log, NAVSEA 3120/l (8-85). Itis maintained in the following manner:

1. Use a separate bell sheet for each shaft eachday. When a station controls more than one shaft,use the same sheet for all shafts controlled by thatstation.

2. Record the time the order was received incolumn 1 (fig. 2-5).

3. Record the order received in column 2.Record minor speed changes by entering therevolutions per minute (rpm) or pitch change

Figure 2-5.—Engineer’s Bell Book, NAVSHIPS 3120/1.

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ordered. Record major speed changes using thefollowing symbols:

1/3—ahead 1/3 speed

2/3—ahead 2/3 speed

I—ahead standard speed

II—ahead full speed

III—ahead flank speed

Z—stop

B1/3—back l/3 speed

B2/3—back 2/3 speed

BF—back full speed

BEM—back emergency speed

4. Enter the rpm corresponding to the majorspeed change ordered in column 3. When theorder is a minor speed change of rpm only, makeno entry in column 2.

5. Record the pitch set in feet (FFG-7 class)or percent (DD-963/DDG-993/CG-47 classes) incolumn 4.

Before going off watch, the throttle operatorand the EOOW sign the log on the two linesfollowing the last entry. The next watch continuesthe record.

When control is at the ship control console(SCC) on the bridge, bridge personnel maintainthe Engineer’s Bell Book; when control is at thecentral control station (CCS), the CCS personnelmaintain the Engineer’s Bell Book. Engine-roompersonnel maintain the Engineer’s Bell Book ifthrottle control is maintained in the engine room.

You cannot make alterations or erasures in theEngineer’s Bell Book. Correct errors in theEngineer’s Bell Book in the same manner as theEngineering Log, by drawing a single line throughthe incorrect entry and recording the correctentry on the following line. The EOOW, officerof the deck (OOD), or watch supervisor, asappropriate, will initial corrected entries.

Automatic Bell Log

On DD-963, DD-993, and CG-47 class ships,the automatic bell logger printout (Automatic Bell

Log) is also a legal record. At the end of eachwatch, the EOOW signs the automatic printoutsin the same manner as the Engineer’s Bell Book.When the automatic bell logger and/or the datalogger are in operation, all bells are automaticallylogged. Unless specified by local instructions, youare not required to maintain a bell book on theDD-963, DD-993, and CC-47 class ships.

Equipment Operating Logs

Watch standers are required to maintain avariety of handwritten machinery logs. Eachcommand prepares its own logs. They coverequipment designated by the type commanders,squadron commanders, and your own command.Items generally covered include waste heat boilers(WHBs), gas turbine generators (GTGs), aircompressors, reduction gears, and line shaftbearings (LSBs). As each command has differentrequirements, the list of logs maintained will vary.

All equipment operating logs have high- andlow-limit set points printed for each reading. Theperson maintaining the logs circles in red all out-of-limits readings. Entries in the remarks sectionof the logs note the reason for the out-of-limitscondition and the action taken to correct thecondition. At the end of each watch, the EOOWshould review and initial all of the logs maintainedon his watch.

PROGRAMS

Engineering petty officers are normallyresponsible for a myriad of administrativeprograms. You will use these programs to manageand record inspections, tests, maintenance, safety,liquid systems, and repairs. No one program ismore important than another, but some requiremore time and paper work. You must keep ontop of each one of these programs to have asuccessful administrative organization.

The administrative programs include safetyprograms, equipment maintenance and repairprograms, and management programs. Some ofthe programs we discuss may overlap into two orthree areas. For our purposes, we will discussthem in their major group.

Safety Program

The objective of the Navy’s Safety Programis to enhance operational readiness by reducingthe frequency and severity of on- and off-dutymishaps to personnel and the cost of material and

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property damage attributed to accidental causes.The use of the term Safety Program in this chaptersignifies both occupational safety and health.

Operating personnel must be thoroughlyfamiliar with the technical manuals and otherpublications concerning equipment under theircare. Operating personnel must continuouslyexercise good judgment and employ commonsense in the preparation, setting-up, and operationof all engines to prevent damage to the enginesand injury to personnel.

Personnel can prevent damage to machineryby properly preparing and operating the equip-ment; by following instructions and proceduresoutlined in the EOSS (which is discussed in thelast section of this chapter); by observingcleanliness in handling all parts of the engine,lubricating oils, and fuel oils; and by beingcompletely familiar with all parts and functionsof the machinery.

You can prevent damage to the ship byoperating the machinery so no loss of poweroccurs at an inopportune time, by keeping enginesready for service in any emergency, and bypreventing hazardous conditions that may causefire or explosion. Always maintain fire-fightingequipment in a “ready to use” state.

You can prevent injury to personnel byhaving a thorough knowledge of duties, byknowing how to properly handle tools and operateequipment, by observing normal precautionsaround moving parts, and by receiving constanttraining.

Other everyday safety habits that you shouldfollow include (1) maintaining clean fuel, air,coolants, lubricants, and operating spaces; (2)preventing the accumulation of oil in the bilgesor other pockets or foundations and subbases; (3)taking care, particularly when on an uneven keel,that water in the bilges does not reach electricalmachinery or wiring; and (4) ensuring that safetyguards are provided at exposed danger points.

SPECIFIC GAS TURBINE SAFETY PRE-CAUTIONS.—In the interest of personnel andmachinery safety, you must adhere to the follow-ing safety precautions specifically related to thegas turbine:

1. Do not attempt to operate equipment byoverriding automatic shutdown or warningdevices.

2. Disconnect batteries or other sources ofelectrical power before performing maintenance.

This prevents injuries from short circuits andaccidental cranking of engines.

3. Avoid holding or touching spark plugs,ignition units, or high-tension leads while they areenergized.

4. When turning an engine by hand, usestandard safety procedures to prevent injuries tofingers or hands.

5. Retain adequate speed control of thepower turbine (PT) by keeping the fuel controland speed control governors connected. Whenoperating or starting an engine, do not, under anycircumstances, disconnect the governors.

6. Do not use oxygen to pressure test fuellines and equipment.

7. Do not use compressed air to spin ball orroller bearings after cleaning them.

8. Take precautions to avoid inhaling vaporsof lacquer thinner, trichlorethylene, and similarsolvents.

9. Avoid changes to the high-speed stop onthe fuel control and adjustments to the speed con-trol governors. If you have to make adjustments,follow the appropriate technical manualprocedure.

10. Follow the appropriate guides in theNAVSEA technical manuals for making periodicinspections and testing the safety control circuitsand automatic shutdown devices.

11. Do not wear jewelry and watches whileworking on GTEs.

12. Take precautions to avoid touchingexposed hot parts of the engine. Do not performmaintenance work until the engine has been shutdown and cooled.

13. To protect against personnel or firehazards, ensure that all thermal insulation and/orshields are intact and sound.

14. If a false start occurs, always purge theengine using the EOSS procedure. This is veryimportant and cannot be overemphasized.

15. Make certain that the combustor drainsoperate freely. Do not allow fuel to accumulatein the combustion chamber prior to light-off.Later firing could cause a hot start.

16. Wear proper ear protection in the engineroom while GTEs are in operation.

17. Ensure all ducting permits free flow. Airintake and exhaust openings must allow un-restricted flow of the gas. The performance of gasturbines drops off quite rapidly with increasedduct losses.

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18. Always test overspeed trips and governormechanisms by following instructions in themanufacturers’ technical manuals. Never test theoverspeed trip by manually overriding the speedcontrol governor. When the overspeed trip doesnot function properly, no overspeed protection

ELECTRICAL SAFETY.—The preventionof accidents is possible. It is your job torecognize unsafe conditions and correct them.Observing safety precautions helps keep yourequipment operating, helps your career in theNavy, and possibly determines whether or not yousurvive.exists.

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Think safety. No person is safer than the mostcareless act performed. Safety is stressed innumerous places throughout this training manual.For a more complete reference of detailed safetyprecautions, refer to Naval Ships’ Technical

Manual, chapters 300 and 400; OPNAVINST3120.32, Standard Organization and Regulationsof the U.S. Navy (SORM); and OPNAV-INST 5100.19, Safety Precautions for ForcesAfloat.

Figure 2-6.—Safety posters.

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Electrical Hazards and Precautions.—Youmust recognize hazardous electrical conditionsand take immediate steps to correct them. Safetyposters (figs. 2-6 and 2-7) help warn of dangersin working areas or help remind you to be safety

conscious. Warning signs (red) and caution signs(yellow) located where hazardous conditionsexist help promote safety.

The danger of shock from the 450-volt alter-nating current (ac) ship’s service system is well

Figure 2-7.—Safety posters.

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recognized by operating personnel in the fleet.This is shown by the relatively few reports ofserious electrical shock received from this voltage,despite its widespread use. However, a numberof shipboard fatalities have been reported due tocontact with 115-volt circuits. Low-voltage (115volts and below) circuits are very dangerous andcan cause death. This is most likely to occur whenthe resistance of the body is lowered by moistureand especially when current passes through oracross the chest. Extra care and awareness of thehazards associated with normal shipboardconditions must be emphasized. Perspirationand/or damp clothing result in a decrease in theresistance of the human body. Low bodyresistance along with the ship’s metal structure arethe breeding grounds for severe electrical shock.

Accidentally placing or dropping a metal tool,a rule, a flashlight case, or any other conductingarticle across an energized line can cause a shortcircuit. The arc and fire that may result on evenrelatively low-voltage circuits can cause extensivedamage to equipment and serious injury topersonnel.

Since the ship’s service power distributionsystems are designed to be ungrounded, manypersonnel believe it is safe to touch oneconductor since no electrical current flows. Thisis not true. If one conductor of an ungroundedsystem is touched while the body is in contact withthe ship’s hull or other metal equipment enclosure,a fatal electric current may pass through the body.TREAT ALL ELECTRIC CIRCUITS ASHAZARDOUS. Where working conditionswarrant it, wear appropriate protective clothing.

Make it a habit to look for and correctdefective tools and equipment, improper ground-ing, and rotating machinery hazards.

Hand Tools .—Normally, you should have noproblems when working with hand tools. It isentirely possible that you have seen somedangerous practices in the use of hand tools thatshould have been avoided. One unsafe practiceinvolves the use of tools with plastic or woodenhandles that are cracked, chipped, splintered,broken, or otherwise unserviceable. Using suchtools will probably result in accidents and personalinjuries, such as cuts, bruises, and foreign objectsbeing thrown in the eyes. If unserviceable handtools are not repairable, discard and replace them.For further instructions on the safe use of handtools, refer to chapter 3 of this TRAMAN andUse and Care of Hand Tools and Measuring Tools,NAVEDTRA 12085.

Portable Electric Power Tools.—Portablepower tools should be clean, properly oiled, and

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in good repair. Before using them, inspect themto see that they are properly grounded. Plug a toolequipped with a three-prong plug only in a three-hole electrical receptacle. Never remove the thirdprong. Make absolutely sure the tool is equippedwith a properly grounded conductor. If the toolhas a metal case, be sure to ground it followingchapter 300 of Naval Ships’ Technical Manual.The newer, double-insulated plastic-framed toolsdo NOT have ground wires and have only a two-prong plug.

Observe all safety precautions when operatingany portable electric equipment. Wear rubbergloves whenever plugging into or unpluggingfrom any 115-volt circuit or under particularlyhazardous conditions. Some of these conditionsinclude environments such as wet decks, bilgeareas, or when working over the side of the shipin rafts or small boats.

Before using any portable electrical equip-ment, visually examine the attached cable withplug (including extension cords, when used).Tears, chafing, exposed insulated conductors, anddamaged plugs are causes for cable or plugreplacement. Where PMS is installed, conducttests following instructions on the maintenancerequirement cards (MRCs).

Other safe practices in the use of portableelectric power tools include the following:

Before using the tool, lay all portablecables so you and others cannot trip over them.Normally, the length of extension cords used withportable tools will not exceed 25 feet. Extensioncords of 100 feet are authorized on flight andhangar deck areas only. Extension cords of 100feet are also found in damage control lockers, butare labeled for Emergency Use Only.

Do not use jury-rigged extension cords thathave metal “handy boxes” for receptacle ends ofthe cord. All extension cords must have noncon-ductive plugs and receptacle housings.

Do not unplug a cord by yanking on it.

When making electrical connections,always start at the load and work backto the source. When disconnecting electricalconnections, start at the source and work towardthe load.

Stow the tool in its assigned place after youare through using it.

RESCUE AND FIRST AID FOR ELECTRICSHOCK.—Your job is risky even under the bestworking conditions. Despite the fact that accidentsare preventable, you run a good chance of

getting shocked, burned, and being exposed to oneor more hazards. If you are at the scene of anaccident, you will be expected to assist the victimas quickly as possible.

When a victim is rendered unconsciousby electric shock, you should start artificialresuscitation as soon as possible. The only logicalpermissible delay is that time required to free thevictim from contact with the electricity in thequickest, safest way. This step must be done withgreat care, otherwise there may be two victimsrather than one.

If contact is with a portable electric tool, light,appliance, equipment, or portable extension cord,turn off the bulkhead supply switch or removethe plug from its bulkhead receptacle.Clearly warn other persons arriving at the scenenot to touch the suspected equipment until it isunplugged. You should seek aid to unplug the device as soon as possible.

Where a victim is in contact with stationaryequipment, such as a bus bar or electricalconnections, pull the victim free if the equipmentcannot be quickly de-energized, or if the ship’soperations or survival prevent immediate securingof the circuits. To save time in pulling the victimfree, improvise a protective insulation for your-self. For example, instead of hunting for a pair ofrubber gloves to use in grasping the victim, youcan safely pull the victim free by using your belt

part of your body to directly touch the hull, metala line, or a wooden cane. During the rescue, do not allow any

structure, furniture, or victim’s skin.

After removing a victim of electric shock fromcontact with the electricity, he or she may needfirst aid, cardiopulmonary resuscitation (CPR),or closed-chest cardiac massage. We are notgoing to discuss these various procedures in thismanual. Your ship’s corpsman will teach them toyou during the annual electrical safety lectureaboard ship.

Equipment Tag-Out Program

An effective tag-out program is necessarybecause of the complexity of modern ships as wellas the cost, delay, and hazard to personnel that

could result from the improper operation ofequipment. The purpose of the equipment tag-outprogram is to provide a procedure to prevent im-proper operation when a component, equipment,system, or portion of a system is isolated or inan abnormal condition. This procedure shouldalso be used when other safety devices, such asblank flanges, are installed for testing,maintenance, or casualty isolation.

The use of DANGER or CAUTION tags isnot a substitute for other safety measures, such aslocking valves, pulling fuses, or racking out circuitbreakers. Tags applied to valves, switches, orother components should indicate restrictions onoperation of systems or equipment, or restrictionsnecessary to avoid damage to safety devices.Never use tags for identification purposes.

The procedures in this program are mandatoryto standardize tag-out procedures used by all shipsand repair activities. The program also providesa procedure for use when an instrument is unreli-able or is not in normal operating condition. It issimilar to the tag-out procedure except that labelsinstead of tags are used to indicate instrumentstatus. The tag-out program must be enforcedduring normal operations as well as duringconstruction, testing, repair, or maintenance.Strict enforcement of tag-out procedures isrequired by both you and any repair activity thatmay be working on your equipment.

RESPONSIBILITY. —The commanding offi-cer is responsible for the safety of the entirecommand. It is the duty of the commanding of-ficer to ensure that all personnel know allapplicable safety precautions and procedures andto ensure compliance with the program. Theengineer officer is responsible to the commandingofficer for ensuring that personnel assigned to theengineering department understand and complywith this program.

When repairs are done by a repair activity, adual responsibility exists for the safety of therepair personnel to ensure that conditions are safefor all work being done. The ship tended is re-sponsible for and controls the tag-out program onthe systems that require work. The repair activityis responsible for ensuring compliance with theprogram.

PROCEDURES.—When you identify theneed to tag out a piece of equipment or a system,you must get permission from an authorizingofficer. The authorizing officer for the engineer-ing department will be the EOOW while underway or the EDO while in port. If the system orequipment tagged is placed out of commission,

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the authorizing officer must get permissionfrom the engineer officer and the commandingofficer. When permission has been received, theauthorizing officer then directs you to prepare thetag-out record sheet and tags.

Normally, the petty officer in charge of thework fills out and signs the record sheet andprepares the tags. The record sheet is filled outfor a stated purpose. All tags for that purpose arenormally listed on one record sheet. Each sheetis assigned a log serial number. All tags associatedwith it are given the same log serial number anda sequential number is entered on the record sheet.For example, tag E107-4 is the fourth tag issuedon the record sheet with the log serial number 107for engineering.

The record sheet includes reference to anydocuments that apply-such as PMS, technicalmanuals, and other instructions, the reasonfor the tag-out, the hazards involved, anyamplifying instructions, and the work necessaryto clear the tags. Use enough tags to completelyisolate the system or circuit being worked on toprevent operation from any and all stations thatcould exercise control. Indicate the location andcondition of the tagged item by the simplest means(for example, FOS-11A, closed).

When the tags and record sheets are filled out,a second person must make an independent checkof the tag coverage.

When attaching the tags, you must ensure thatthe item is in the position or condition indicated

Figure 2-8.—Caution tag (colored yellow).

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on the tag. As you attach each tag, you then mustsign the tag and initial the record sheet. After alltags are attached, a second qualified personensures the items are in the position andcondition indicated, verifies proper tag placement,signs the tags, and initials the record sheet.

TYPES OF TAGS.—The following is a list ofthe various tags and the applications required tobe used from time to time.

Caution Tag.—A YELLOW tag (fig. 2-8) isused as a precautionary measure to providetemporary special instructions or to indicate thatunusual caution must be exercised to operate

equipment. These instructions must give thespecific reason that the tag was installed. The useof such phrases as DO NOT OPERATEWITHOUT EOOW PERMISSION is notappropriate since equipment or systems are notoperated unless permission has been granted byresponsible authority. A CAUTION tag is NOTused any time personnel or equipment can beendangered while performing evolutions usingnormal operating procedures; a DANGER tag isused in this case.

Danger Tag.—A RED tag (fig. 2-9) is used toprohibit the operation of equipment that could

Figure 2-9.—Danger tag (colored red).

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jeopardize the safety of personnel or endangerequipment. Under no circumstances should equip-ment be operated when tagged with DANGERtags.

Out-Of-Calibration Labels.—ORANGElabels (fig. 2-10) are used to identify instrumentsthat are out of calibration and may not workproperly, This label indicates the instrument maybe used for system operation only with extremecaution.

Out-Of-Commission Labels.—RED labels(fig. 2-11) are used to identify instruments thatdo not work properly because they are defectiveor isolated from the system. This indicates theinstrument cannot be relied on and must berepaired and recalibrated, or be reconnected tothe system before use.

ENFORCEMENT. —The tag-out log is keptin a designated space, usually CCS. Supervisorywatch standers review the log during watch relief.Active tag-outs are spot checked periodically toensure tag integrity is being maintained.

An audit of the tag-out log is conducted bythe EDO every 2 weeks while in port, prior togetting under way, and weekly if in the yards orat a maintenance availability. Results of the auditare reported to the engineer officer.

To ensure that tag-out procedures are enforcedproperly, the engineer officer checks the logfrequently. If he notes any errors, he brings themto the attention of the proper personnel.

Personnel Protection Programs

In this section we will discuss three areas thatare of great concern to you as a watch stander.These are heat stress, noise pollution, andhandling hazardous materials.

Figure 2-10.—Out-of-calibration label (colored orange).

Figure 2-11.—Out-of-commission label (colored red).

HEAT STRESS.—While working in hotenvironments or during strenuous physical workin cool as well as hot ambient conditions,personnel are apt to suffer heat disorders. Theresults are loss of time from duty and possibledeath. Many of these illnesses result in prolongedor permanent impairment of the affected person’sability to withstand heat. Unacclimatized andoverweight personnel are particularly susceptibleto heatstroke and other heat disorders.

Because of these hazards, exposure ofpersonnel to extended periods of strenuousphysical work in spaces of high ambienttemperature must conform with NAVMEDP-5052-5.

NOISE POLLUTION.—Control of noiseemission is an important aspect of pollutioncontrol. Noise above certain sound levels cancause a wide variety of unwanted effects onpersonnel, ranging from discomfort and anxietyto illness and deafness. Because of these hazards,exposure of personnel to high sound levels mustcon fo rm wi th OPNAVINST 5100 .23 .

Noise levels generated from GTEs are on theorder of 100 to 125 decibels (db). These levels areenough to cause partial or total deafness tounprotected personnel. Three primary noisesources exist in a gas turbine installation. Theyare (1) the inlet passages, (2) the exhaust ducts,and (3) the engine core.

Noise from the inlet passages and exhaustducts can be controlled by the installation ofacoustic insulation to the structure. Noise fromthe engine core is controlled by the modulesurrounding the engine. To prevent negation ofthe soundproofing characteristics of structuralinsulation, the insulation must be constantly main-tained at a high degree of repair.

Personnel working in an environment wherethe noise level is greater than 84 db must wearapproved hearing protection. If you must be in

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an area where the noise level is greater than 104db (such as running checks on a gas turbinemodule (GTM) with the module door open), youmust wear double hearing protection -earplugsand earmuff protectors.

HANDLING HAZARDOUS MATE-RIAL.—Because of the high rotational speeds andhigh temperatures generated by GTEs, petroleum-based oils are not suitable for use. Most of to-day’s GTEs use synthetic-based oils containingpolyesters. These oils are usually less viscous thanthose used in reciprocating engines.

The synthetic oil in general use aboard gasturbine ships is MIL-L-23699. You must usespecial precautions and handling proceduresbecause these oils can remove paint and are toxic.When handling synthetic oils, you must avoidspills. Prolonged contact with the oil can causeskin irritations, such as dermatitis. Inhalation ofvapors can cause irritation of the respiratory tract.When working with this oil, you should alwayswear a face shield, rubber gloves, and an apron.If you do come in contact with synthetic oil,remove any oil-soaked clothing and wash withsoap and water. If you have oil splashed into youreyes, immediately flush them with water and seekmedical attention.

Fluid Management Program

In this section, we will discuss the receipt,transfer, stowage, and discharge of lube oils. Theflammable liquid management program, theanalysis of petroleum test results, and thecorrective action required for abnormal conditionswill also be discussed. You will find thatknowledge of fluid management is useful in yourday-to-day evolutions and essential to meetingyour watch-stander qualifications as oil king. Formore specific details and procedures, refer toNaval Ships’ Technical Manual, chapters 262 and541.

LUBE OIL.—Proper lubrication is vital to theoperation of all shipboard machinery. In thefollowing paragraphs we will describe lube oilquality control, the handling of new lube oils andhydraulic fluids (including synthetic oils), and theprevention and clean-up of oil spills.

Quality Control.—Each batch of lubricantmust be tested, as required by the specificationsin effect at the time the batch enters the supplysystem. Samples of the oils stored in the supply

system must be taken periodically to ensureproduct quality. When NAVSEA receives reportsof lubricant difficulties, it takes immediate stepsto determine the problem by testing used andunused lubricant samples and by investigatingequipment malfunctions. In this manner, productquality is being maintained and is upgraded whennecessary.

Care of New Lube Oil.—Upon receiving newlube oil on board ship, and immediately beforeplacing the oil in the storage tanks, you mustthoroughly test it using the procedures specifiedin Naval Ships’ Technical Manual, chapter 262.Be certain that the proper grade has been deliveredand that the oil meets all physical and chemicalproperties described in the procurement specifica-tion. New lube oil should be delivered to shipsin a clear and bright condition. If the new oil doesnot meet the procurement specification, it mayhave deteriorated or have been contaminatedduring storage or handling. Shore laboratorytesting is required to determine usability.

New oil is delivered to ships either in bulk bytank trucks or as packaged products in drums,pails, or cans. Before off-loading or handlingMIL-L-17331 (2190 TEP) tank truck deliveries,sample the oil and visually check all truckcompartments. Shore laboratory testing may berequired to determine usability. Check for intactseals on commercial trucks and verify deliverydocuments. If oil quality or quantity is question-able, do not take the oil on board until theproblem is resolved with the activity personnelresponsible for the delivery. When delivery is byNavy trucks, it should include a laboratory testreport of the lube oil quality. Ensure that the truckhose is connected to the correct ship manifold.Upon completion of delivery, sound the lube oiltanks and verify all quantities with the truck meterreadings.

Packaged lubricating oil is normally sealed andthe containers are marked to identify the content.Do not use the oil if the container markings arenot clear. Fifty-five gallon drums are fitted withcap seals on the bungs. If these seals are missingor damaged, do not use the oil until the qualitycan be verified by shore laboratory analysis. Wheninitially opening a new drum and pail, take a thiefsample and visually inspect it for quality. If thesample is contaminated or appears abnormal,isolate the container and do not use until thequality can be established. If other containersshow similar quality problems, submit a defectivematerial report (NAVSUPINST 4440.120). Before

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using packaged lube oil, you should filter itthrough a 60-mesh or finer screen. Do not pouroil directly from drums or cans into the operatingequipment. Before introducing new or renovatedoil into the circulating systems or storage tanks,pass it through an operating centrifugal purifierto remove contaminants.

You will have to maintain specimens ofsatisfactory oil in properly labeled and corkedglass containers. Upon receiving a new supply ofoil, take samples for comparison with thespecimens of the same brand to make certain thatthe correct oil has been received. Every oil hasdefinite general characteristics, such as color,odor, and specific gravity, that an experiencedengineer may recognize. These specimens are alsouseful in checking for darkening of in-use oils.

Precautions Against Oil Spills.—Any plannedindustrial process, operation, or product mustintegrate the prevention of environmentalpollution. The preferred method of abatementand control of environmental pollution is at thesource of the pollutants.

You should know the potential sources of oilspills and oil waste that may cause pollution ifproper procedures are not carried out. The follow-ing is a list of common sources of oil and oilywaste that find their way into the water:

1. Spillage during fueling, defueling, andinternal transfer operations

2. Leakage through hull structure into bilges3. Stripping from the contaminated oil settling

tank4. Ballast water from fuel tanks of non-

compensated fuel systems or bulk carriers5. Ballast water from compensated fuel tank

systems during refueling, defueling, and internaltransfer operations

6. Tank cleaning operations7. Leakage and drainage from equipment and

systems8. Contaminated oil from centrifugal purifiers9. Used oil from equipment during an oil

change

Before any fueling, defueling, or internaltransfer operation is started, ensure that allmachinery and piping systems have been checkedfor tightness and signs of leaking glands, seals,and gaskets. When changing oil or adding oil tomachinery, take care not to spill the oil into thebilge. Have a drip pan and rags ready for use ifneeded. Keep a close watch when centrifugal

purifiers are in operation to make sure they donot lose the water seal and dump the oil into thebilge or the contaminated oil tank. During tankcleaning operations, pump all oily waste from thetank into the sludge barge.

Since control of shipboard oil pollution iscomplicated by the many and varied sources ofoily waste, ships have oil pollution controlsystems. These systems serve to

1. reduce oily waste generation,2. store waste oil and oily waste,3. monitor oil and oily waste,4. transfer or off-load waste oil and oily waste

to shore facilities, and5. process oily waste.

It is the responsibility of the training officersto ensure that formal training is provided to keypersonnel responsible for maintaining andoperating pollution control equipment.

Reporting and Clean-Up of Oil Spills.—Alloil spills and slicks or sheens within the 50-mileprohibited zone of the United States must bereported immediately in following the provisionsof OPNAVINST 5090.1. Ships have been giventhe capability to provide immediate and remedialaction until relieved by shore-based response unitsor, in the case of non-Navy or foreign ports, toclean up the entire spill. Shore-based units areseldom available in non-Navy or foreign ports.

A cleanup kit has been developed for use byships’ crews. A description of the kit and instruc-tions for its use will be found in the U.S. NavyOil Spill Containment and Cleanup Kit, Mark I,NAVSEA 0994-LP-013-6010. This manual in-cludes safety precautions applicable to the use ofthe kit, as well as the recommended shipboardallowance. The Navy training film MN-11316documents and demonstrates the use of the kiton an actual spill. Many times quick reaction bya trained crew can result in the containment of,and often in the collection of, the entire spillwithout the assistance of shore-based personnel.

F-76 FUEL OIL (NAVY DISTILLATE).—Fuel system management involves proceduresrelated to the receipt of fuel and the maintenanceof the fuel system equipment. In addition, itinvolves those procedures that limit the dischargeof fuel into the water. Under this topic, we willdiscuss general requirements for receipt, storage,testing, and tank stripping of F-76 fuel. For more

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specific information, refer to Naval Ships’Technical Manual, chapter 541.

Receiving Fuel .—Just before replenishment,tanks that were ballasted must be tested for watercontamination and stripped as necessary. At thebeginning, midpoint, and end of replenishment,as a minimum, draw a fuel sample from a testconnection and test for bottom sediment andwater (BS&W). The maximum allowable BS&Wof an acceptable replenishment sample is 0.1 per-cent. You may use a “clear and bright” ap-pearance during fueling as a secondary indicationof acceptable fuel quality pending BS&W deter-mination. You may accept only fuels conform-ing to MIL-F-16884G (F-76) or, as an alternate,MIL-5624 (JP-5 and F-44). When fueling fromNATO sources, you can accept F-75 fuel as anacceptable substitute. F-44 is the NATO designa-tion for JP-5, and F-75 is the NATO designationfor fuel that has a lower pour point than F-76.Lighter colored fuels, in general, tend to have lesssediment (particulate matter) than darker fuels.They present a lesser filtration burden. Test non-compensated storage tanks for water contamina-tion 24 hours after filling and strip as necessary.

Service Tank Replenishment.—You must testnonseawater-compensated fuel storage tanks(from which the service or auxiliary service tankis to be replenished) for water contamination.Before beginning fuel transfer, strip the tanks asnecessary. Sample the centrifugal purifierdischarge and visually test it 5 minutes after in-itiation of transfer, and every 30 minutesthereafter. An acceptable sample is one visuallydetermined to be clear and bright. When a sam-ple fails to meet the clear and bright criteria, thisindicates a need for tank inspection and/orpurifier cleaning.

Recirculate the service tank using thecentrifugal purifier for the maximum timeavailable, but no less than 3 hours, or for as manyhours as required to recirculate the contents ofthe service tank. Recirculation reduces the amountof solid contaminants in the fuel.

Fuel contaminants may be less dense, moredense, or as dense as the fuel itself. As a result,one pass through the purifier may remove as muchas 50 percent of the incoming contaminants or aslittle as 10 percent. Multiple passes can eventuallyremove as much as 90 percent of the totalcontaminants or at least reduce the level to belowthat required for engine use. Reducing the levelof contamination in the fuel service tank can alsoresult in a reduction in the usage of coalescer and

separator elements and of prefilter elements if theyare used. Ensure that the centrifugal purifier bowlis clean. Otherwise, the recirculation will be oflittle value.

Before placing the standby (or auxiliary)service tank in use, test the tank bottom for watercontamination and strip as necessary. Recirculatethe propulsion service tank using the centrifugalpurifier for the maximum time available.

it 5 minutes after a service tank is placed onSample the filter/separator discharge and test

suction and at least once every 4 hours duringsystem operation. An acceptable sample containssediment less than 2.64 milligrams per liter (mg/l)and free water less than 40 parts per million(ppm). Failure of the filter/separator to achievethe required fuel quality indicates either the needfor coalescer element replacement or insufficientservice tank recirculation.

Tank Stripping .—At the earliest opportunity,the ship’s force must determine (and record) theheight of the stripping tail pipe terminus relativeto the tank bottom. Stripping of noncompensatedtanks is conducted when the water level exceedsthe height of the stripping tail pipe. Use a thiefsample, water-indicating paste, or a tank strippingsample to determine the water level. Terminatestripping when the water level falls below thestripping tail pipe terminus. This is evidenced bytank bottom testing or when the stripping pumpdischarge sample does not indicate significant freewater.

You must test noncompensated fuel tanks,fuel gravity feed tanks, fuel head tanks, and JP-5emergency head tank bottoms weekly for thepresence of water. Strip them as necessary. Inaddition, strip these tanks before fuel receipt,transfer, or service.

F-44 FUEL OIL (JP-5).—In this section wewill discuss the general procedures for receiving,stripping tanks, and testing of F-44 fuel. As aGSE3 or GSM3, you will be involved in one ormore of the above procedures on a daily basis.You will note that testing requirements for JP-5fuel differ somewhat from those of F-76 fuel.While the test equipments used in propulsion fuelsare the same, the procedures and criteria aredifferent. The sampling procedures and timerequirements also differ.

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Receiving JP-5 Fuel.—Before and duringreceipt of JP-5 fuel, take samples in containersthat permit visible inspection of the fuel. Thecriteria for the acceptance or rejection of JP-5 fuelis as follows:

1. A clear, clean sample indicates acceptableJP-5 fuel is being received.

2. If the sample is cloudy, stop the replenish-ment operation until the source of the cloud isdetermined by observing the sample.

If the cloud disappears at the bottom,air is present and the JP-5 fuel is acceptable.

If the cloud disappears at the top, wateris present. In this event, fleet oilers will beginproper stripping and will usually correct cloudinesscaused by large amounts of free water.

If the cloud does not begin clearing in5 minutes, heat the sample to about 25° abovethe temperature of the fuel in the tank from whichthe sample was taken. If the sample clears, thecloud was due only to dissolved water and theJP-5 is acceptable. If the sample does not clear,excessive water is present and you should acceptthe JP-5 fuel only in an emergency.

3. If the sample contains excessive solid con-tamination, accept the JP-5 only in an emergency.To make JP-5 that contains excessive amounts ofwater and/or solids acceptable for aircraft use,you can use the following methods:

Extend the settling time.

Meticuously strip the tank.

Properly use and maintain the cen-trifugal purifier and the filter/separators in thetransfer system and the main service system.

Stripping Procedures.—You should continuestripping JP-5 tanks until a sample from thestripping pump outlet indicates all sediment andwater in the tanks has been removed. A visualsample is sufficient for storage tank stripping.However, under certain circumstances, you musttest service tanks using an free water detector andcontaminated fuel detector. For detailed information onrequirements for stripping of storage and service tanks, referto Naval Ships’ Technical Manual, chapter 542.

Testing JP-5 Fuel.—Testing of JP-5 fuel isdone at an approved testing laboratory and also

aboard ship. Personnel must take samples for off-ship tests monthly or as ordered if operating conditions per-mit. Take samples from the following locations:

1. The service filter discharge2. One nozzle per quadrant

Take samples from the service system filterand fueling station nozzles after the system hasbeen recirculated for at least 2 minutes. Ensurethe fuel samples are typical of the fuel deliveredto the aircraft. Take samples during aircraft fuel-ing operations.

You must use glass containers of 1 quartminimum size. Ensure the inner cap seal does notcontain paraffin, corrosive metal, or othermaterial liable to contaminate fuel. The containersshould have noncorrosive, noncontaminating capsto eliminate false or misleading laboratorymessage reports that could require disruption offueling from a satisfactory filter.

Thoroughly clean and dry the containers.Inspect them for cleanliness before use. Beforesampling JP-5 fuel, rinse the clean container andflush it several times with the fuel being sampled.Then fill it, leaving about a l/2-inch space forexpansion. Cap and mark the glass containerimmediately. Mark the glass sample container toinclude all of the following items:

1. Heading: Avia t ion Fuel Sample

2. Identification of the ship submitting thesample (name and hull number).

3. The fueling station number or servicefilter/seperator discharge sampled.

4. The type of fuel.5. The date the sample is drawn.6. The name of the person drawing the

sample.7. Laboratory instructions: Test for sediment,

flash point, and corrosion (if ap-plicable). Notify the ship by message if thesediment contamination exceeds 2.0mg/1, if flashpoint is below 136°F (57.8°C) or if FSII is less than0.03 percent. The message should specifyitems 3, 4, and6, as well as the sample results. A follow-up routinereport of the test results for all samples submitted is requested.

8. Resamples of reported contaminatedsamples must include the following markings:Resample, request immediate analysis, and themessage report.

9. On special samples, outline suspected problemsand symptoms.

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You must ensure the minimum amount oftime possible elapses between sampling and receiptof the report of laboratory analysis. Ships haveto use the test results to ensure clean fuel. Scheduleroutine and monthly sampling for optimumuse of available transportation to fuel laboratorylocations. Take samples immediately before enter-ing port while the ship’s aviation fuel system isin normal operating condition. Deliver thesamples by the quickest means possible to thenearest fuel laboratory. For detailed informationon the sampling and testing requirements of JP-5fuel, refer to Naval Ships’ Technical Manual,chapter 542.

BOILER WATER/FEEDWATER.—Onships with WHBs, you may be responsible fortesting and treating the WHB with variouschemicals to maintain the boiler water withinprescribed limits. To be certified for boiler-waterand feedwater testing, you must attend school,pass the course, and be certified by your ship’scommanding officer as being qualified. In thissection we will not attempt to go into detail asto each individual test and requirement, but wewill discuss the reasons for treating the WHB andyour responsibilities for the necessary tests andadministration.

Shipboard Water Cycle.—The overall ship-board water cycle is a closed system in which feed-water is fed to the boiler, the water is heated togenerate steam, the steam does work, and it is thencondensed and returned to the feedwater system.Water for the cycle is obtained from seawater,which is taken into a distiller and evaporated toproduce distillate. The distillate is stored in reservefeedwater tanks until needed as makeup feed.When needed to replace system losses, it ispumped to the system. It is then pumped to thedeaerating feed tank (DFT), if the ship is soequipped, where oxygen and other gases areremoved. This deaerated water, now called feed-water, is pumped to the boiler where heat isapplied. The boiler water is converted to steam,and then it is used to operate auxiliary equipmentand provide heat energy to different parts of theship. When most of the heat energy has beenremoved, the steam is condensed in the condenser.Then it is ready to be recycled once again.

Because the cycle is continuous and closed, thesame water remains in the system except fornonrecoverable losses, such as boiler blowdowns,laundry presses, and miscellaneous leaks. Makeup

feedwater is required to compensate for thesesystem losses.

Although the shipboard water cycle iscontinuous, different terminology is used todescribe the water at different points. Thesedistinctions are necessary because water qualitystandards vary throughout the system. Thefollowing terms identify the water at variouspoints:

1. Distillate—The evaporated water that isdischarged from the ship’s distilling plant. Thedistillate is stored in the feedwater tanks whichare designated as the on-line feed tank and reservefeed tank by the chief engineer.

2. Feedwater—The term used to designate thewater stored in the feed tanks.

3. Boiler water—The feedwater becomesboiler water as it enters the boiler and boiler tubes.

4. Condensate—After the steam has done itswork, it is returned to its liquid state by coolingin a condenser. The condenser is a heat exchangerin which seawater cools the steam and returns itto liquid form. It is then returned to the feed tank.

Contamination. —Boilers cannot be operatedsafely and efficiently without careful attention to,and control of, feedwater and boiler water quality.With proper control of water chemistry, properplant operation, and proper lay-up during idleperiods, boilers should last the life of the ship withno need to renew boiler tubes. If water conditionsare not controlled within allowable limits, rapiddeterioration of waterside surfaces, scale forma-tion, and carry-over will occur. This leads toserious boiler casualties. Because boilers concen-trate all feedwater contaminants as steam isgenerated, boiler water quality and reliable boileroperation depend directly upon control of feed-water quality.

Because of ship operations, propulsionsystems use water from two sources, seawater andshore water. For boiler operations, these watersare considered contaminated due to variouschemicals in them. These chemicals can causeserious boiler failures because of chemicalreactions within the boiler. Some of the effectsof contamination of boiler water and feedwaterare as follows:

1. pH (acidic and caustic corrosion)-Failureto maintain a correct pH balance can causecorrosion. Excessive acidity causes the film on theboiler tube metal to dissolve, resulting in corrosionof the inner tubes of the boiler. Excessive

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alkalinity can cause caustic corrosion, which cancause damage as severe as acidic corrosion.

2. Hardness-Calcium and magnesium arethe major hardness constituents and primarysources of scale in boilers. The major source ofscale is shore water. Scale deposits act asinsulators and reduce heat transfer across asurface. Deposits on the boiler tubes will causethe temperature of the metal to increase untiloverheating, metal softening, blistering, andfailure occur.

3. Dissolved oxygen (pitting)-When dis-solved oxygen enters the boiler water, it causeslocalized corrosion and pitting of tube metal.

4. Chloride (pitting corrosion)-Excessivechloride readings indicate seawater contamina-tion. Chloride dissolves the protective layer onboiler metal and pitting corrosion instead ofgeneral corrosion results.

The boiler cannot be operated safely andefficiently without careful attention to, andcontrol of, feedwater and boiler water.

Waste Heat Boiler Treatment.—The require-ments for treating and maintaining WHBs arecontained in Naval Ships’ Technical Manual,chapter 220. To maintain the WHB, you will needto perform the required tests on the boiler water,feedwater, and shore water. The WHBs aretreated by two methods, continuous injectionand/or the batch feed method. Normally, thepreferred method is continuous injection. If thismethod fails, you can use the batch feed method.

The boilers are treated with trisodiumphosphate (TSP) and disodium phosphate (DSP).The TSP provides alkalinity and phosphate. TheDSP provides additional phosphate withoutsignificantly affecting the alkalinity.

Testing of the WHB for alkalinity, phosphate,and chloride is at the following frequencies:

1. Within 30 minutes after the generatoris started

2. Within 1 hour before beginning blowdowns3. Thirty to 60 minutes after blowdowns4. As often as required to maintain the limits,

but at least every 8 hours (maximum of8 hours between samples)

5. Thirty to 60 minutes after batch chemicaltreatment

6. Within 1 1/2 hours before the generator issecured

7. Whenever unusual conditions exist asdetermined by the EOOW or EDO

If an emergency should arise and it becomesnecessary to use shore source feedwater notmeeting the requirements for feedwater, sampleand test the boiler water hourly. Then treat itaccordingly. Hourly testing followed by requiredtreatment must continue until the distilling plantsare producing the required quality water and thedistillate can be used as makeup.

Handling and Safety of Treatment Chem-icals.—When handling the TSP or caustic soda,you must wear a face shield, rubber gloves, anda rubber apron. Concentrated solutions of thesechemicals are corrosive and will cause burns tothe skin, eyes, and body tissue. If you get TSP,caustic soda, or their solutions anywhere on yourbody, flush the area with cold water. Obtainimmediate medical attention if it enters your eyes.

Ensure the safety dispensing bottle is markedand used for boiler-water treatment chemicalsonly. The safety dispensing bottle is made fromlinear polyethylene, which has a maximum usetemperature of 176°F. As the TSP and DSPdissolve, they generate heat. Water temperaturewill increase slightly. Do not use hot water todissolve the chemicals. This may cause the safetydispensing bottle to exceed its temperature uselimits.

You can add TSP to water or vice versawithout difficulty. You should always add DSPto water because DSP tends to cake if water ispoured over it.

Physical Security Program

Physical security involves the security of theengineering plant to ensure unauthorized entryinto unoccupied space and unauthorized tamper-ing with engineering equipment does not occur.Basically, physical security entails the installationand use of security devices (locks and locking pins)to prevent unauthorized personnel from alteringthe configuration of the engineering plant. Thiscould include preventing engineering personnelfrom using fluids without reporting their use. Itcould also prevent anyone from sabotaging theplant. Specific instructions on the managementof the physical security program are contained inthe EDORM.

The physical security program should bedesigned with common sense and accountabilityin mind. If something is to be locked, the keys

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should only be issued to persons who havea need to use them. A program that giveseveryone access to everything is ineffective.Some method must be maintained to allowduty section personnel access to keys, whennecessary. Methods for this include watch keyrings, duty engineer keys, and an engineering keylocker.

The reduction gear covers are also includedin physical security. The keys for these high-security locks are held by the chief engineer.Since no opening of a reduction gear is allowedwithout his approval, he should be the onlyperson allowed to have these keys. For moreinformation on reduction gear security, refer tothe Naval Ships’ Technical Manual, Chapter 241,“Propulsion Reduction Gears, Couplings, andAssociated Components.”

Environmental Quality

All Navy personnel are responsible for findingways to reduce pollution of our land, air, andwater. You can do your part by strictly complyingwith U.S. Navy regulations and instructions. Formore detailed information concerning pollutionabatement, refer to the Environmental andNatural Resources Manual, OPNAVINST 5090.1.

Gauge Calibration

Calibration of shipboard gauges and metersis essential to ensure proper operation of complexengineering equipment. Calibration is normallydone by specially trained personnel. Most of thiscalibration is scheduled under 3-M Systemsscheduling. Use standard 3-M forms to requestoutside assistance from the readiness supportgroup (RSG) in your homeport for this calibra-tion. For detailed information on the gaugecalibration program, refer to the Naval Ships’Technical Manual, Chapter 491, “ElectricalMeasuring and Testing Equipment,” and Chapter504, “Pressure, Temperature, and OtherMechanical and Electromechanical MeasuringInstruments.”

Valve Maintenance

Each ship in the Navy depends on the integrityof its valves to prevent flooding, to correctlysecure systems, and to ensure proper managementof liquid systems. Since a ship has numerouspiping systems with many valves, a methodto ensure proper valve maintenance is needed.The 3-M Systems includes maintenance on

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many valves, but it does not have completeshipwide system valve coverage. A soundvalve maintenance program can ensure propermaintenance of all shipboard valves.

When starting an effective valve maintenance,personnel must verify all valves in a piping system.To accomplish this, they must use a variety ofresources. These include EOSS drawings, ship’sprints, and damage control plates. After a list isdeveloped, you will be responsible for checkingit against the actual ship’s piping to determine thecondition of each valve and ensure each valve isactually in place. Maintenance workers assignedto this task should not change the status of anyvalve. This is to ensure that they do notinadvertently change the status of the engineeringplant. Periodic valve maintenance ensures thatvalves are packed properly, lubricated, paintedcorrectly (for example, no paint on threads orstem), have the correct type and color coding of handwheelinstalled, and have identification tags installed.Check all valves with locking devices to ensurethe locks are in place, adequate, and intact.

Supervisors of the valve maintenance programgenerate and maintain local forms to keep arecord of valve maintenance. Most of themaintenance can be scheduled during underwayperiods; however, you should ensure that propertag-out procedures are followed. For additionalinformation on valve maintenance, refer toOPNAVINST 3540.5.2.

PERSONNEL QUALIFICATIONSTANDARDS

The PQS documents describe the knowledgeand skills a trainee must have to perform certainduties. They speed up the learning progress sinceeach person knows exactly what information toobtain to prepare for qualifying in increasinglycomplex duties. They individualize learning soeach person may take advantage of opportunitiesto learn on the job. They place the responsibilitiesfor learning on the trainee and encourage self-achievement. They offer a means for the super-visor to check individual speed and performanceby providing a convenient record of accomplish-ment.

Since the PQS have been assembled by groupsof experienced officers and petty officers, theyattempt to represent the guidance that would befurnished if each person had an individualinstructor throughout each step.

Every PQS is designed to support advance-ment in rating requirements as stated in the

Navy Enlisted Manpower and PersonnelClassifications and Occupational Standards,NAVPERS 18068-E.

Every PQS document contains the followingsections:

1. Introduction2. Glossary of Qualification Standard Terms3. Table of Contents4. 100 series-Fundamentals5. 200 series-Systems6. 300 series-Watch Standing

7. Bibliography8. Feedback Forms

MAIN SPACE FIRE DOCTRINE

The Main Space Fire Doctrine is a ship-generated instruction that promulgates policy,implements procedures, and assigns responsi-bilities for action in the combatting of main spacefires. According to this instruction, main spacefires can be combatted with installed Halon 1301systems, installed aqueous film-forming foam(AFFF), portable fire-fighting equipment, EOSS,underway and in-port fire parties, and repairparties. The procedures contained in thisinstruction are to be followed by all personnel forconditions specified, such as in-port cold iron,auxiliary steaming, and under way.

ENGINEERING OPERATIONALSEQUENCING SYSTEM

The Navy has developed a system known asthe EOSS. Essentially, the EOSS is to the operatoras the PMS is to the maintainer.

Main propulsion plants in ships of today’smodern Navy are becoming more technicallycomplex as each new class of ship is built and joinsthe fleet. Increased complexity requires increasedengineering skills for proper operation. Ships thatlack the required experienced personnel havehad material casualties. These casualties havejeopardized their operational readiness. Rapidturnover of engineering personnel who man andoperate the ships further compounds the problemof developing and maintaining a high level ofoperator and operating efficiency.

The Navy has been increasingly aware of theseproblems. Studies have been done to evaluate themethods and procedures presently used inoperating complex engineering plants. The results

of these studies have shown that in many instancessound operating techniques were not followed.Some of the circumstances found to be prevailingin engineering plants are as follows:

The information needed by the watchstander was usually scattered throughout publica-tions that were generally not readily available.

The bulk of the publications were notsystems oriented. Reporting engineering personnelhad to learn specific operating procedures from“old hands” presently assigned. Such practicescould ultimately lead to misinformation ordegradation of the transferred information. Thesepractices were costly and resulted in nonstandardoperating procedures, not only between adjoiningspaces, but also between watch sections within thesame space.

Posted operating instructions often did notapply to the installed equipment. They wereconflicting or incorrect. No procedures wereprovided for aligning the various systems withother systems.

The light-off and securing schedules wereprepared by each ship and were not standardizedbetween ships. The schedules were written forgeneral, rather than specific, equipment or systemvalues. They did not include alternatives betweenall the existing modes of operation.

Following these studies, NAVSEA developedthe EOSS, which is designed to help eliminateoperational problems. The EOSS involves theparticipation of all personnel from the departmenthead to the watch stander. The EOSS is a set ofsystematic and detailed written procedures. TheEOSS uses charts, instructions, and diagramsdeveloped specifically for the operational andcasualty control function of a specific ship’sengineering plant.

The EOSS is designed to improve theoperational readiness of the ship’s engineeringplant. It does this by increasing its operationalefficiency and providing better engineering plantcontrol. It also reduces operational casualtiesand extends the equipment life. These objectivesare accomplished first by defining the levelsof control; second, by operating within theengineering plant; and last, by providing eachsupervisor and operator with the informationneeded. This is done by putting these objectives

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in words they can understand at their watchstation.

The EOSS is composed of three basic parts.

The User’s Guide

The engineering operational procedures(EOP

The engineering operational casualtycontrol (EOCC)

EOSS User’s Guide

The User’s Guide is a booklet that explainsthe EOSS package and how it is used to the ship’sbest advantage. It contains document samplesand explains how they are used. It providesrecommendations for training the ship’s personnelusing the specified procedures.

The EOSS documentation is developed usingwork-study techniques. All existing methods andprocedures for plant operation and casualtycontrol procedures are documented. These includethe actual ship procedures as well as thoseprocedures contained in available referencesources.

Each action is subjected to a criticalexamination to evaluate the adequacy of thepresent procedures. At the completion ofthis analytic phase, new procedural steps aredeveloped into an operational sequencing system.Step-by-step, time-sequenced procedures, andconfiguration diagrams are prepared to showthe plant layout in relation to operationalcomponents. The final step in the developmentphase of an EOSS is a validation on board ship.This is done to ensure technical accuracy andadequacy of the prepared sequencing system. Allrequired corrections are made. They are thenincorporated into the package before installationaboard ship.

The resulting sequencing system providesthe best tailored operating and engineeringoperational casualty control procedures avail-able pertaining to a particular ship’s propulsionplant, Each level is provided with the informationrequired to enable the engineering plant torespond to any demands placed upon it.

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Engineering Operational Procedures

The operational portion of the EOSS, theEOP, has all the information necessary for theproper operation of a ship’s engineering plant. Italso has guides for scheduling, controlling, anddirecting plant evolutions through operationalmodes. This includes receiving shore services, tovarious modes of in-port auxiliary plant steam-ing, to underway steaming.

The EOP documentation is prepared forspecifically defined operational stages. These aredefined as stages I, II, and III.

Stage I deals with the total engineering plantunder the direct responsibility of the plant super-visor (EOOW). The EOOW coordinates the plac-ing in operation and securing of all systems andcomponents normally controlled by the variousspace supervisors. This person also supervisesthose functions that affect conditions internal tothe engineering plant, such as jacking, testing, andspinning main engines. The EOP documentationassists the plant supervisor to ensure optimumplant operating efficiency, proper sequencing ofevents in each operational evolution, and thetraining of newly assigned personnel. During aplant evolution, the EOOW designates controland operation of the following systems andcomponents:

Systems that interconnect one or moreengineering plant machinery spaces and electricalsystems.

Major components, such as main engines,and electrical generators.

Systems and components required tosupport the engineering plant or other shipfunctions, such as distilling plants, air com-pressors, fire pumps, and auxiliaries. These maybe placed in operation or secured in response todemand upon their services.

To assist the plant supervisor with these opera-tions, the EOP section provides the followingdocuments:

Index pages listing each document in thestage I station by identification number andtitle.

Plant status diagrams (fig. 2-12) providinga systematic display of the major systems andcross-connect valves as well as a graphicpresentation of the major equipment in eachmachinery space. These diagrams are used tomaintain a current plot of systems’ alignment andequipment operating status.

A diagram for plant steaming conditionsversus optimum generator combinations. Thisdiagram delineates the preferred electric power

generator combinations for the various plantoperating conditions. This diagram is alsoprovided in the stage II electrical documenta-tion.

System alignment diagrams delineating thepreferred initial and final alignment for eachengineering plant.

A diagram for equipment versus speedrequirement delineating the equipment normallyrequired for various ship speeds.

Figure 2-12.—Sample plant status diagram.

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A diagram for shore services connectionlocations. This diagram delineates the location ofshore service connections for steam, electricalpower, feedwater, potable water, firemain, andfuel oil.

Training diagrams (fig. 2-13) delineatingeach major piping system to aid in plantfamiliarization and training of newly assignedpersonnel. These diagrams indicate the relativelocations of lines, valves, and equipment.

Stage II deals with the system component levelunder supervision of the space supervisor in eachengine room (ER) and auxiliary machinery room(AMR), and the electric plant control console(EPCC) operator (EPCC watch). In stage II, thespace supervisor accomplishes the tasks delegatedby the plant supervisor. The EOP documentationassists the space supervisor in properly sequencingevents, controlling the operation of equipment,maintaining an up-to-date status of the opera-tional condition of the equipment assigned, and

Figure 2-13.—Sample training diagram.

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training newly assigned personnel. To assistthe space supervisor in the effort, the EOPsection provides the following stage II documents:

Index pages listing each document byidentification number and title for each specifiedoperating group, such as ER, AMR, or electricalsystem.

Space procedure charts (similar to the plantprocedure chart) providing the step-by-stepprocedures to be accomplished within a space tosatisfy and support the requirements of the plantprocedure charts.

Space status board providing a schematicof major systems and a tabular listing of themajor equipment within the individual machineryspaces for maintaining a plot of system alignmentsand equipment operating status. This board issimilar in configuration to the casualty controlboard for the stage I documentation shown infigure 2-14.

Diagram for electrical plant statusdelineating generators, switchboards, andshorepower connections within the electricaldistribution systems. This diagram is provided in

both the electrical operating group and in the stageI (EOOW) documentation for maintaining a plotof the system alignment.

Diagram for plant steaming conditionsversus optimum generator combinations providedin the electrical operating group documentation.This specifies the preferred electric powergenerator combination. This diagram is the sameas that provided in the stage I documentation.

Training diagrams of each major pipingsystem developed for stage I, plus diagrams ofsuch systems as the fuel-oil service system and themain engine lube oil system that are normallylocated within the machinery spaces.

Stage III deals with the system componentlevel under the supervision of componentoperators. The component operators place equip-ment in and out of operation, align systems, andmonitor and control their operation. This is doneby manipulating required valves, switches, andcontrols. Stage III documents include thefollowing:

Index pages listing each document byidentification number and title for each specified

Figure 2-14.—Casualty control board.

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system, such as the fuel-oil service system and the Component procedure cards as required tolube oil service system. support each operation or alignment.

Component procedure cards providing Alignment diagrams (fig. 2-15) amplifyingstep-by-step procedures for systems’ alignment or the written procedure to assist the componentcomponent operation. operator in proper systems’ alignment. Alignment

Figure 2-15.—Sample component/system alignment diagram.

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diagrams are provided whenever two or morealignment conditions exist for a given system orcomponent.

The operational use of EOP documentation isof primary importance at all levels in controlling,supervising, and operating the engineering plant.

Engineering Operational Casualty Control

The engineering operational casualty control(EOCC) is the casualty control portion of theEOSS. It contains information relevant to therecognition of casualty symptoms and theirprobable causes and effects. Also, it hasinformation on actions taken to prevent acasualty. It specifies procedures for controllingsingle- and multiple-source casualties.

Casualty prevention must be the concern ofeveryone on board. Proper training of allpersonnel must provide an adequate knowledgeand experience in effective casualty prevention.The EOCC manual has efficient, technicallycorrect casualty control and prevention pro-cedures. These procedures relate to all phases ofan engineering plant. The EOCC documentspossible casualties that may be caused by humanerror, material failure, or battle. The EOCCmanual describes proven methods for the controlof a casualty. It also provides information forprevention of further damage to the component,the system, or the engineering plant.

The EOCC manuals (books) are available ateach watch station for self-indoctrination. Themanuals contain documentation to assist engineer-ing personnel in developing and maintainingmaximum proficiency in controlling casualties tothe ship’s propulsion plant.

Proficiency in EOCC procedures is maintainedthrough a well-administered training program.Primary training concentrates on the control ofsingle-source casualties. These are casualties thatmay be attributed to the failure or malfunctionof a single component or the failure of piping ata specific point in a system. Advanced trainingconcentrates on the control of multiple casualtiesor on conducting a battle problem. An effective,well-administered watch-stander training program

will contain, as a minimum, the followingelements:

Recognition of the symptoms

Probable causes

Probable effects

Preventive actions that may be taken toreduce, eliminate, or control casualties

An EOSS package is not intended to beforgotten once it is developed and installed aboarda ship. It offers many advantages to the ship’soperational readiness capabilities and providesdetailed step-by-step sequencing of events for allphases of the engineering plant operation. Becauseit is work studied and system oriented, the EOSSprovides the basic information for the optimumuse of equipment and systems. It does this byspecifying correct procedures tailored for aspecific plant configuration.

The EOSS is not intended to eliminate theneed for skilled plant operators. No program orsystem can achieve such a goal. The EOSS is atool for better use of manpower and skillsavailable. Although the EOSS is an excellent toolfor shipboard training of personnel, it is primarilya working system for scheduling, controlling, anddirecting plant operations and casualty controlprocedures.

SUMMARY

The information you studied in this chapterhas provided you with a general knowledge of thepublications, maintenance records, logs, andprograms that you will use in your day-to-dayroutine aboard ship. We have strived to presentan overview of a majority of the administrativefunctions of a GSE3 or GSM3. All of these areasare important in their own right. Some of thesubjects will be discussed in greater detail in laterchapters. In this chapter we referred you to otherpublications that will give you a more in-depthexplanation of the material covered. You shouldstudy them to become a more proficient andreliable technician.

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CHAPTER 3

TOOLS AND TEST EQUIPMENT

As a third class GSE or GSM, you will beworking with different types of hand tools andtesting equipment. Your responsibilities includethe routine maintenance of the equipment in yourengineering spaces. After reading this chapter, youshould be able to describe some of the devices youmay use during your maintenance procedures. Thedevices discussed in this chapter are not all thetools and equipment that a GS3 might use. Forfurther information, refer to Use and Care of Hand Toolsand Measuring Tools, NAVEDTRA 12085, and the NavyElectricity and Electronics Training Series(NEETS), modules 1, 3, and 16. To determine thespecific device recommended for each procedure,refer to the appropriate manufacturers’ technicalmanuals, the Naval Ships’ Technical Manual,and/or other information books.

HAND TOOLS

Everyone has used a hand tool at one time oranother for some type of job. The types of hand

tools described in the following sections are somethat you might use, but with which you possiblyare not familiar.

WIRE-TWISTER PLIERS

Wire-twister pliers (fig. 3-1) are three-waypliers that hold, twist, and cut. They are designedto reduce the time used in twisting safety wire onnuts and bolts. To operate them, grasp the wirebetween the two diagonal jaws, and then use yourthumb to bring the locking sleeve into place.When you pull on the knob, the twister twirls andmakes uniform twists in the wire. You can pushback the spiral rod into the twister withoutunlocking it. Then another pull on the knob willgive a tighter twist to the wire. A squeeze onthe handle unlocks the twister. Now you cancut the wire to the desired length with the side cut-ter. Occasionally, lubricate the spiral of thetwister.

Figure 3-1.—Wire-twister pliers.

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293.4Figure 3-2.—Safety-wiring practices.

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Figure 3-3.—Safety-wiring electrical connectors.

Figures 3-2 and 3-3 show examples of safety-wiring techniques that you should follow. Thefigures do not show all possible safety-wiringcombinations; however, safety-wiring practicesshould conform to those shown. Consult specificmanufacturers’ technical manuals for approvedmaterials and techniques to use in any givenapplication. You will find step-by-step proceduresfor safety-wiring in Propulsion Gas TurbineModule LM2500, Trouble Isolation, volume 2,part 3, S9234-AD-MMO-050/LM2500, section8.1.

WRENCHES

While performing your maintenance pro-cedures, you will use a variety of wrenches. Thissection is about the recommended wrenches youneed to be familiar with while working on the gasturbine engine (GTE). You will also learnabout wrenches and hand tools that are notrecommended for use on the GTE.

Recommended Wrenches

The only hand tools you should use on GTEsare chrome-plated, nickel-plated, or unplatedhand tools. The CROWFOOT wrench (fig. 3-4,view A) is a very handy tool to use for

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Figure 3-4.—Crowfoot, flare nut, and torque adapterwrenches.

maintenance procedures. You can use it to gainaccessibility to hard to reach areas where otherwrenches are difficult to use. The head ofthe wrench is designed like an open-endwrench. However, the other end is designed toaccommodate accessories, such as extensions,breaker bars, and torque wrenches. Crowfootwrenches come in a wide variety of sizes like thoseof the open-end type of wrenches.

The FLARE NUT wrench (fig. 3-4, view B)is similar to a box wrench. The difference is a slotcut in the wrench head which allows it to fit overtubing or wiring and then onto the fastener. Thereare two types of this wrench you might use onyour ship. The first type is long handled, similarto the regular box wrench, with a different sizeon each end. The second type is short. The otherend is designed to accommodate accessories, suchas extensions, breaker bars, and torque wrenches.These flare nut wrenches are made with 6, 8, 12,and 16 points or notches. The wrenches on yourship will generally be 12 points because of thenumerous 12-point fasteners used on the GTE.You can also use the 12-point wrench effectivelyon 6-point (hex head) fasteners. As with thecrowfoot wrenches, the flare nut wrenches comein a wide variety of sizes.

The TORQUE ADAPTER wrench (fig. 3-4,view C) is similar to a box wrench. The other endis designed to accommodate accessories, such asextensions, breaker bars, and torque wrenches.They are used to reach nuts and bolts that are inhard to reach locations.

Nonrecommended Wrenchesand Hand Tools

The adjustable wrench and cadmium-platedor silver-plated tools are NOT recommended for

Figure 3.5.—Types of common taps.

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you to use while working on GTEs. You might,however, use them elsewhere for maintenance.

The ADJUSTABLE wrench is useful becauseit will fit nuts and bolts that are odd-sized orslightly damaged or burred. BUT, good engineer-ing practice dictates that you use the proper sizewrench for the work you are doing. Parts on theGTEs are made of high-quality materials and arestandard sizes. Because of the design of theadjustable wrench, it could cause extensivedamage to the GTE. If it slips, gouging and/orscratching could occur. Do not use a part if it isdamaged in any way.

DO NOT use CADMIUM-PLATED orSILVER-PLATED hand tools when working ontitanium parts of GTEs. If you use these handtools, you could cause particles of cadmium orsilver to become imbedded in the titanium parts.At temperatures above 600°F, the cadmium orsilver can cause embrittlement. This results inoverstressed areas and possible cracking. Toprevent this, use chrome-plated, nickel-plated, orunplated hand tools on titanium parts.

TAPS AND DIES

Taps and dies are used to cut threads in metal,plastics, or hard rubber. The taps are used forcutting internal threads, and the dies are used tocut external threads. Many different types of tapsare available. However, the most common are thetaper, plug, and bottoming (fig. 3-5).

The taper (starting) hand tap has a chamferlength of 8 to 10 threads. You would use thesetaps when starting a tapping operation and whentapping through holes.

Plug hand taps have a chamfer length of 3 to 5threads and are designed for use after the tapertap.

Bottoming hand taps are used for threadingthe bottom of a blind hole. They have a very shortchamfer length of only 1 to 1 1/2 threads. This

Figure 3-6.—Rethreading die.

tap is always used after the plug tap has beenused. Both the taper and plug taps should precedethe use of the bottoming hand tap.

Dies are available in several differentshapes and are of the solid or adjustable type.Figure 3-6 shows a solid type of rethreading die.It is used mainly for dressing over bruised orrusty threads on screws or bolts. It is availablein a variety of sizes for rethreading Americanstandard coarse and fine threads. These dies areusually hexagon in shape and can be turned witha socket, box, open-end, or any wrench that willfit.

Round split adjustable dies (fig. 3-7) are called“button” dies. You can use them in either handdiestocks or machine holders. The adjustment in

the screw adjusting type is made by a fine-pitchscrew which forces the sides of the die apart orallows them to spring together. The adjustmentin the open adjusting type is made by three screwsin the holder, one for expanding and two forcompressing the dies. Round split adjustable diesare available in a variety of sizes to cut Americanstandard coarse and fine threads, special formthreads, and the standard sizes of threads that areused in Britain and other European countries. Forhand threading, these taps and dies are held in tapwrenches and diestocks (fig. 3-8).

THREAD CHASERS

Thread chasers are threading tools that haveseveral teeth. They are used to rethread (chase)

Figure 3-7.—Types of adjustable dies.

Figure 3-8.—Tap wrenches and diestocks.

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damaged external or internal threads (fig. 3-9).These tools are available to chase standardthreads. The internal thread chaser has its cuttingteeth located on a side face. The external threadchaser has its cutting teeth on the end of the shaft.The handle end of the tool shaft tapers to a point.

SCREW AND TAP EXTRACTORS

Screw extractors are used to remove brokenscrews without damaging the surroundingmaterial or the threaded hole. Tap extractors areused to remove broken taps.

Figure 3-9.—Thread chasers.

Tap extractors are straight and have prongsfrom end to end (fig. 3-10, view A). Theseextractors are available to remove broken tapsranging from 1/4 inch to 1 inch in outsidediameter. Spiral tapered extractors (fig. 3-10,view B) are sized to remove screws and boltsranging from 3/16 inch to 3 l/2 inches in out-side diameter.

Most sets of extractors include twist drills anda drill guide. Tap extractors are similar to thescrew extractors and are sized to remove tapsranging from 3/16 to 3 l/2 inches in outsidediameter.

MECHANICAL FINGERS

You can retrieve small articles that have falleninto places where you cannot reach them by handwith the mechanical fingers. You can also use thistool when starting nuts or bolts in difficult areas.The mechanical fingers (fig. 3-11) have a tubecontaining flat springs that extend from the endof the tube to form clawlike fingers, much likethe screw holder. The springs are attached to arod that extends from the outer end of the tube.A plate is attached to the end of the tube; a similarplate, which you press with your thumb, isattached to the end of the rod. A coil spring placedaround the rod between the two plates holds them

Figure 3-10.—Tap and screw extractors.

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apart and retracts the fingers into the tube. Withthe bottom plate grasped between your fingers andenough thumb pressure applied to the topplate to compress the spring, the tool fingersextend from the tube in a grasping position.When the thumb pressure is released, the toolfingers retract into the tube as far as theobject they hold allows. Thus, enough pressureis applied on the object to hold it securely.Some mechanical fingers have a flexible endon the tube to permit their use in close quartersor around obstructions.

NOTE: Do NOT use mechanical fingersas a substitute for wrenches or pliers.The fingers are made of thin sheetmetal or spring wire and you caneasily damage them by overloading.

INSPECTION MIRROR

Several types of inspection mirrors areavailable for use in maintenance. The mirroris issued in a variety of sizes and may be

round or rectangular. The mirror is connectedto the end of a rod and may be fixed or adjustable(fig. 3-12).

The inspection mirror will aid you in makingdetailed inspection where you cannot directly seethe inspection area. By angling the mirror, andwith the aid of a flashlight, you can inspect mostrequired areas. A late model inspection mirrorfeatures a light to aid you in viewing those darkplaces where the use of a flashlight is notconvenient.

Figure 3-12.—Adjustable inspection mirror.

Figure 3-11.—Mechanical fingers.

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WIRE-WRAP HAND TOOLS

Basically, wire wrapping is simply winding asolid wire tightly around a stiff pin to provide agood junction. Figure 3-13 shows some ofthe types of hand tools currently availablefor this purpose. Wire-wrap hand tools areused with different sized bits and sleeves,depending on the size of the wire beingused. Some ships have wire-wrap kits forthe GSs. On other ships you might needto borrow these hand tools from otherdivisions, such as the Data Systems Tech-nicians or the Fire Control Technicians. Theprinciples and techniques of wire-wrappingwill be discussed in chapter 10 of this trainingmanual.

PRECISION TOOLS

When performing maintenance or repairon various equipment, you are required to

adjust, tighten, or space components to specifictolerances. To do this, you must have anunderstanding of how to use and read themeasuring instruments involved, such as torquewrenches, micrometers, and depth gauges.This section covers some of the measuringinstruments you need to become familiarwith.

TORQUE WRENCHES

Torque wrenches are used to tightennuts, bolts, and fasteners to specific toler-ances. Due to the variations in temperaturesassociated with operating equipment, variousparts are placed under stress. If parts arenot tightened evenly and in a uniform man-ner, one or two bolts or fasteners couldbear the brunt of the stress. This can re-sult in damaged and broken parts. Proper tighten-ing following the manufacturer’s instructions

Figure 3-13.—Examples of wire-wrap tools.

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and standards will prevent this. Torquewrenches must be kept in calibration. Ensure youuse ONLY calibrated torque wrenches.

Types of Torque Wrenches

The three most commonly used torquewrenches are the deflecting beam, dial in-dicating, and micrometer setting types (fig. 3-14).When using the deflecting beam and the dialindicating torque wrenches, you read the torqueon a dial or scale mounted on the handle of thewrench.

The torque wrench you will probablyuse is the micrometer setting. This type iseasier to use because you do not have towatch a dial or pointer while using thewrench.

To use a micrometer setting wrench, un-lock the grip and adjust the handle to thedesired setting on the micrometer scale. Then,relock the grip. Install the required socketor adapter to the square drive of the handle.Place the wrench assembly on the nut orbolt and pull in a clockwise direction witha smooth, steady motion. (A fast or jerkymotion results in an improperly torqued unit.)When the applied torque reaches the torquevalue, which is indicated on the handle setting,

a signal mechanism automatically issues anaudible click. Next the handle releases, or“breaks,” and moves freely for a shortdistance. You can easily feel the releaseand free travel and know when the torquingprocess is complete.

The procedure for using the deflectingbeam and the dial indicating wrenches isthe same as the micrometer setting wrench;however, you have to hold the torque atthe desired value until the reading is steady.

Torque Values

Torque values are expressed in pound-inches (lb-in.) or pound-feet (lb-ft). One pound-inch (or 1 pound-foot) is the twisting forceof 1 pound applied to a twist fastener (suchas a bolt or nut) with 1 inch (or 1 foot)of leverage. This twisting force is appliedto the fastener to secure the components.When you are working with or reading torquevalues, they are usually expressed in inch-pounds (in.-lb) or foot-pounds (ft-lb).

A manufacturer’s or a technical manualgenerally specifies the amount of torque youshould apply to a fastener. To assure gettingthe correct amount of torque on the fastener,use the wrench according to the manufacturer’sinstructions. When using an adapter (suchas a crowfoot wrench) with a torque wrench,you must calculate the correct adapter torque.

Figure 3-14.—Torque wrenches.

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Figure 3-15 shows a step-by-step method tocalculate torque.

Proper Use of Torque Wrenches

Use the torque wrench which will read aboutmidrange for the amount of torque to be applied.

BE SURE THAT THE TORQUE WRENCHHAS A CURRENT CALIBRATION LABELON IT BEFORE YOU USE IT. The accuracy oftorque-measuring depends a lot on how thethreads are cut and on the cleanliness of thethreads of the item being torqued. Make sure youinspect and clean the threads. If the manufacturer

293.7Figure 3-15.—Determining torque wrench correction factors.

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specifies a thread lubricant, use it to obtain themost accurate torque reading.

Torque wrenches are delicate and expensivetools. Observe the following precautions whenusing them :

a nontorque wrench and retighten to the correcttorque with the indicating torque wrench.

1. Do not move the setting handle below thelowest torque setting when you use the micrometersetting. However, place it at its lowest setting priorto returning it to storage.

2. Do not use the torque wrench to applygreater amounts of torque than its rated capac-ity.

6. Do not use a torque wrench before check-ing its calibration date. Calibration intervals havebeen established for all torque tools used in theNavy. When a tool is calibrated by a qualifiedcalibration activity at a shipyard, tender, or repairship, a label showing the next calibration due dateis attached to the handle. Check this date beforeyou use a torque tool to ensure that it is not over-due for calibration.

3. Do not use the torque wrench to breakloose bolts that have been previously tightened.

4. Do not drop the wrench. The resulting joltcan affect its accuracy.

You can find specific information on torquevalues for equipment in the manufacturer’stechnical manual.

SIMPLE CALIPERS

5. Do not apply a torque wrench to a nut that Simple calipers are used in conjunctionhas been tightened. Back off the nut one turn with with a scale to measure diameters. Figure 3-16

Figure 3-16.—Simple calipers-noncalibrated.

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shows the calipers most commonly used inthe Navy.

Outside calipers for measuring outsidediameters are bow-legged; those used for insidediameters have straight legs with the feet turnedoutward. You adjust calipers by pulling orpushing the legs to open or close them. You canmake fine adjustment on calipers by tapping oneleg lightly on a hard surface to close them or byturning them upside down and tapping on thejoint end to open them.

Spring-joint calipers have the legs joinedby a strong spring hinge and linked togetherby a screw and adjusting nut. For measur-ing chamfered cavities (grooves), or for useover flanges, transfer calipers are available.They are equipped with a small auxiliaryleaf attached to one of the legs by a screw.The measurement is made as with ordinarycalipers; then the leaf is locked to the leg.The legs may be opened or closed as neededto clear the obstruction, and then broughtback and locked to the leaf again, which restoresthem to the original setting.

A different type of caliper is the her-maphrodite, sometimes called an odd-leg caliper.This caliper has one straight leg ending in a sharppoint, sometimes removable, and one bow leg.The hermaphrodite caliper is used chiefly forlocating the center of a shaft or for locating ashoulder.

You can find out more about how touse and to care for simple calipers in

Use and Care of Hand Tools and Measuring Tools,NAVEDTRA 12085 chapter 3.

SLIDE CALIPER

The main disadvantage of using ordinarycalipers is that they do not give a direct readingof a caliper setting. As explained earlier, you mustmeasure a caliper setting with a rule. To overcomethis disadvantage, use slide calipers (fig. 3-17).This instrument is occasionally called a caliperrule.

Slide calipers can be used for measuring out-side, inside, and other dimensions. One side ofthe caliper is used as a measuring rule, while thescale on the opposite side is used in measuring out-side and inside dimensions. Graduations on bothscales are in inches and fractions. A locking screwholds the slide caliper jaws in position during use.Stamped on the frame are the words IN and OUT.You use these in reading the scale while makinginside and outside measurements, respectively.

VERNIER CALIPER

A vernier caliper (fig. 3-18) consists of anL-shaped member with a scale engraved on thelong shank. A sliding member is free to move onthe bar and carries a jaw which matches the armof the L. The vernier scale is engraved on a smallplate that is attached to the sliding member.

Perhaps the most distinct advantage of thevernier caliper, over other types of caliper, is the

Figure 3-17.—Slide caliper.

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ability to provide very accurate measurementsover a large range. It can be used for bothinternal and external surfaces. To use the verniercaliper, you must be able to measure with a slidecaliper and read a vernier scale.

MICROMETER

In much wider use than the vernier caliper isthe micrometer caliper, commonly called the“mike.” A person who is working with machineryor in a machine shop must thoroughly understandthe mechanical principles, construction, use, andcare of the micrometer. Figure 3-19 shows an

outside micrometer caliper with the various partsclearly indicated. The most commonly usedmicrometers are accurate to measure distances tothe nearest 1/1,000th of an inch, but if you needto measure to the nearest 1/10,000th of an inch,you can use a vernier micrometer caliper. Themeasurement is usually expressed or written as adecimal; so you must know the method of writingand reading decimals.

Types of Micrometers

There are three types of micrometers that aremost commonly used throughout the Navy: theoutside micrometer caliper (including the screw

28.4BFigure 3-18.—Vernier caliper.

Figure 3-19.—Nomenclature of an outside micrometer caliper.

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thread micrometer), the inside micrometer, andthe depth micrometer (fig. 3-20). The outsidemicrometer is used for measuring outsidedimensions, such as the diameter of a piece ofround stock. The screw thread micrometer is usedto determine the pitch diameter of screws. Theinside micrometer is used for measuring insidedimensions. For example, it is used to measurethe inside diameter of a tube or hole, the bore ofa cylinder, or the width of a recess. The depthmicrometer is used for measuring the depth ofholes or recesses.

Selecting the Proper Micrometer

The types of micrometers commonly used aremade so that the longest movement possiblebetween the spindle and the anvil is 1 inch. Thismovement is called the range. The frames ofmicrometers, however, are available in a widevariety of sizes, from 1 inch up to as large as24 inches. The range of a 1-inch micrometer isfrom 0 to 1 inch; in other words, it can be usedon work where the part to be measured is 1 inchor less. A 2-inch micrometer has a range from1 inch to 2 inches, and it measures only workbetween 1 and 2 inches thick; a 6-inch micrometerhas a range from 5 to 6 inches, and it measures

only work between 5 and 6 inches thick.Therefore, in selecting a micrometer, you mustfirst find the approximate size of the work to thenearest inch, and then select a micrometer thatfits it. For example, to find the exact diameterof a piece of round stock, use a rule and find theapproximate diameter of the stock. If it is 3 1/4inches, you need a micrometer with a 3- to 4-inchrange to measure the exact diameter. Similarly,with inside and depth micrometers, you must fitrods of suitable lengths into the tool to get theapproximate dimension within an inch; then, youread the exact measurement by turning thethimble. The size of a micrometer indicates thesize of the largest work it measures.

Reading a Micrometer Caliper

Figure 3-21 shows an enlarged sleeve andthimble scales on the micrometer caliper. Tounderstand these scales, you need to know thatthe threaded section on the spindle, whichrevolves, has 40 threads per inch. Therefore, everytime the thimble completes a revolution, thespindle advances or recedes l/40 inch (0.025 inch).

Notice that the horizontal line on the sleeveis divided into 40 equal parts per inch. Every

Figure 3-20.—Common types of micrometers.

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Figure 3-21.—Sleeve and thimble scales of a micrometer(enlarged).

fourth graduation is numbered 1, 2, 3, 4, and soon, representing 0.100 inch, 0.200 inch, and soon. When you turn the thimble so that its edgeis over the first sleeve line past the 0 on thethimble scale, the spindle has opened 0.025 inch.If you turn the spindle to the second mark, it hasmoved 0.025 inch plus 0.025 inch or 0.050 inch.You use the scale on the thimble to complete yourreading when the edge of the thimble stopsbetween graduated lines. This scale is dividedinto 25 equal parts, each part representing 1/25of a turn; and 1/25 of 0.025 inch is 0.001 inch.As you can see, every fifth line on the thimblescale is marked 5, 10, 15, and so on. The thimblescale, therefore, permits you to take very accuratereadings to the thousandths of an inch; since youcan estimate between the divisions on thethimble scale, fairly accurate readings to the tenthousandth of an inch are possible.

The closeup in figure 3-22 helps you to under-stand how to take a complete micrometer reading.Count the units on the thimble scale and add themto the reading on the sleeve scale. The reading inthe figure shows a sleeve reading of 0.250 inch(the thimble having stopped slightly more thanhalfway between 2 and 3 on the sleeve) with the10th line on the thimble scale coinciding with thehorizontal sleeve line. Number 10 on this scale

Figure 3-22.—Read a micrometer caliper.

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means that the spindle has moved away from theanvil an additional 10 times 0.001 inch, or 0.010inch. Add this amount to the 0.250 inch sleevereading, and the total distance is 0.260 inch.

Reading a Vernier Micrometer Caliper

Many times you are required to work toexceptionally precise dimensions. Under theseconditions you should use a micrometer that isaccurate to ten thousandths of an inch. Thisdegree of accuracy is obtained by the addition ofa vernier scale. This scale (fig. 3-23) furnishes thefine readings between the lines on the thimblerather than making you estimate. The 10 spaceson the vernier are equivalent to 9 spaces on thethimble. Therefore, each unit on the vernier scaleis equal to 0.0009 inch, and the differencebetween the sizes of the units on each scale is0.0001 inch.

When a line on the thimble scale does notcoincide with the horizontal sleeve line, you candetermine the additional space beyond thereadable thimble mark by finding which verniermark coincides with a line on the thimble scale.Add this number, as that many ten thousandthsof an inch, to the original reading. In figure 3-24,see how the second line on the vernier scalecoincides with a line on the thimble scale.

This means that the 0.011 mark on the thimblescale has been advanced an additional 0.0002 of

Figure 3-23.—Vernier scale on a micrometer.

Figure 3-24.—Read a vernier micrometer caliper.

an inch beyond the horizontal sleeve line. Whenyou add this to the other readings, the reading willbe 0.200 + 0.075 + 0.011 + 0.0002 = 0.2862of an inch, as shown.

TEST EQUIPMENT

As a GSE or a GSM, you are responsible foroperating various pieces of test equipment whenperforming maintenance and repair procedures.You must fully understand the operation of thistest equipment and must be able to interpret theresults of these tests.

Some of the equipment you will find in use aregauge calibration equipment, vibration analysisequipment, horoscopes, fuel testing equipment,and electrical/electronic test equipment.

DEADWEIGHT TESTER/GAUGECOMPARATOR

Several types of deadweight testers areavailable. The types are determined by whetherthe pressure medium is fluid or gas. The fluiddeadweight testers use oil or water as the pressuremedium; bifluid deadweight testers use oil andwater. Pneumatic deadweight testers use a gas,usually pure nitrogen, as the pressure medium.

You will ONLY use the deadweight tester/gauge comparator to compare a gauge to a knownpressure. You will do this by applying a pressurewith the pump to the standard comparator gaugeand the gauge to be compared.

Since the construction details vary for thedifferent types of testers, you should read themanufacturer’s catalog or the applicable Naval

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Ships’ Technical Manual for specific care andmaintenance information.

ULTRAVIOLET TEST UNIT

The ultraviolet (UV) test unit is a battery-operated unit that outputs an ultraviolet lightbeam to test the ultraviolet light flame detectors.The test unit is a cylindrical object. It has a pistoltype of grip that contains a trigger to control theunit attached to the bottom side of the cylinder.

HEAT GUN

The heat gun is a device that outputs forcedhot air. This is used to test the temperaturedetectors in the gas turbine enclosure. The heatgun looks and works on the same principle as ablow dryer.

STROBOSCOPE

The stroboscope is an instrument that permitsrotating or reciprocating objects to be viewed inter-mittently and produce the optical effect of slowingdown or stopping motion. For example, electricfan blades revolving at 1,800 rpm will apparentlybe stationary if viewed under a light that flashesuniformly 1,800 times per minute. At 1,799flashes per minute, the blades will appear to rotateforward at 1 rpm, and at 1,801 flashes per minute,they will appear to rotate backward at 1 rpm.

The strobotac (fig. 3-25) is an electronic flashdevice that has a very short flash duration (on theorder of a few millionths of a second). This allowsvery rapid motion to be stopped. The strobotacbox contains a swivel mount with a strobotronlamp in a parabolic reflector, an electronic pulsegenerator that controls the flashing rate, and apower supply that operates from the ac powerline. The flashing rate is controlled by the largeknob. The corresponding speed in rpm is indicatedon an illuminated dial viewed through windowsin the knob.

BORESCOPE

The borescope is an instrument used to inspectthe internal parts of the GTE. Inspection isperformed by passing a fiber optic probe (rigidor flexible) through parts in the engine. Thisallows the operator to view the engine parts in thegas flow path.

Figure 3-25.—Strobotac.

Function of the Borescope

The word borescope is made up of two words.These are bore, which means cylindrical cavity(such as in the case of a hydraulic cylinder or gunbarrel), and scope, which means to observe. Inthe borescope application of inspecting the gaspath components of GTEs, the majority of theobserving to be done is at some angle relative tothe axis of the borescope inspection hole (port).You can think of the borescope as a type ofperiscope.

This periscope would be a simple device if itwere not for the need to illuminate the objectobserved. In the equipment described in this

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manual, fiber optics are used to transmit lightfrom a remote source to an opening at the endof the borescope probe. The use of fiber opticsremoves the heat of the bulb from the probe andeliminates the electrical parts from inside it.

The Wolf and Eder borescopes now in use inthe fleet are the rigid, probe fiber optic illuminatedtype. Both borescopes have been manufacturedto the same specifications; although some minordesign differences exist, their operating principlesremain unchanged.

The three basic items that are required for astandard rigid, fiber illuminated borescope setup(fig. 3-26) are as follows:

1. Fiber light projector-A remote unit thatsupplies the light needed to see the object.

2. Fiber light guide-A flexible cable com-posed of fiber strands that transmits the light fromthe light source to the borescope.

3. Probes and adapters-A system of prismsand lenses surrounded by light carrier bundles thattransmit light to illuminate the object. The prismand lens system returns the illuminated imagefrom the distal tip to the eye.

Borescope Use

The borescope is a precision periscopeinstrument. It is designed for you to inspectthe gas path components of GTEs withouthaving to disassemble the engine. The bore-scope probes (periscopes) contain precisionoptics that are easily damaged by rough handling.Foam-padded carrying cases are provided toinsulate these instruments from shock. The lightprojector is in one case, and all the remainingequipment is in the other case. Many differentkinds of probes and adapters are availablefrom borescope manufacturers. The equipmentdescribed in this manual has been selectedto meet the inspection requirements of theLM2500 GTE. The need to inspect othermachinery, in most instances, requires additionalborescoping components of a configurationto be compatible with the geometry of thatequipment. Additional borescope accessoriesneeded to inspect any machine other than theLM2500 GTE will be described when we discussthe inspection of that particular piece ofequipment.

Figure 3-26.—Wolf borescope equipment.

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Three Wolf probes are used for inspecting the GTE are less than 7 inches from the inspectionLM2500 GTE (fig. 3-27). Each probe has a unique ports). Although all probes have been made toconfiguration that has special capabilities. The the same specification, some variance in theparameters that are varied to achieve these proper- magnification factor is provided by the Wolf andties are the viewing angle, the field of vision, and Eder No. 1 probes. The Eder probe has athe magnifying factor. Understanding the magnification factor of 1:1 at 5 inches instead ofcapabilities of each probe will help you find out at 7 inches. Eder is working to standardize theirthe best way to use it. The numbering of the probe. However, the user should be aware thatprobes has nothing to do with their importance it is an Eder and verify the optical characteristicsor the sequence in which they are used. of the probe in his kit.

Figure 3-27 provides parameters that definethe probes. A quick review of these parametersreveals the characteristics of each probe. ProbeNo. 1, with a 90-degree direction of vision, hasa narrow field of view and a high magnificationfactor. The magnification factor of 1:1 at7 inches means that an object 7 inches away canbe seen as true size, but objects closer than 7inches can appear magnified. This probe is verydifficult to use for searching for an object becauseof its narrow field of view. Also, its short depthof field requires constant refocusing. Theimportant feature of probe No. 1 is its ability toprovide greater magnification to an object alreadyidentified (most inspection areas in the LM2500

Probes No. 2 and No. 3 are identical with theexception that No. 2 is looking down (100° fromaxis of probe) and No. 3 is looking up (70° downfrom axis of the probe). Objects 2 inches awayfrom the ends of these probes appear at their truesize. Objects closer than 2 inches appearmagnified, and objects further than 2 inchesappear reduced. The advantage of these probesis that they have a wide view and are suited forsearching. They also have a large depth of fieldwhich does not require constant refocusing. Withthese probes, all objects 1/4-inch distance fromthe probe tip to infinity will be in focus.

The direction of view is always given indegrees. Some manufacturers consider the

Figure 3-27.—Probe used with Wolf borescope.

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eyepiece as 0°; therefore, a direct view scopewould be 180° (Wolf). Others start with theprobe tip as 0° and count back toward theeyepiece. The Wolf borescope probes (fig. 3-27)use a direction of vision corresponding to thestandards of the medical profession.

Borescoping and evaluation of results froman engine inspection are best learned fromexperience. You should work with an experiencedinspector when learning the use of the borescope.Technical manuals provide acceptable and non-acceptable limitations for engine damage; mostships have borescope inspection report sheets. Youwill turn these sheets in to the chief engineer; theyshow the inspection results and your evaluations.From these sheets the chief engineer can make thedecision to continue to use the engine or to havethe engine repaired to operable condition.

VIBRATION ANALYSIS

Vibration analysis is a method of determininga piece of machinery’s mechanical condition bymeasuring its vibration characteristics undernormal operating conditions. Vibration analysisis an extremely effective tool. This analysis canaccurately indicate whether a machine hasmechanical defects and which specific part isdefective.

With a vibration analysis program on boardyour ship, you can detect machinery problems intheir early stages. In this way, you can preventcomplete failure of the equipment and possiblesevere damage to the equipment.

You can use this analysis program to make abaseline profile of new equipment. When doingpreventive maintenance, you can compare the

Figure 3-28.—Model 309 vibration meter,

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baseline with the current readings to check themachinery condition. It can also be used totroubleshoot equipment for suspected problemsand to verify that proper repairs have been madeto overhauled equipment.

The principle of vibration analysis is basedon the fact that all machines vibrate. Thesevibrations are caused by the allowable toleranceerrors that are inherent in the machinesmanufacture; they form the baseline vibrationsignature of the individual machine. Similarmachines have similar vibration signaturesthat differ from each other only by theirmanufacturing and installation tolerances.

When a machine’s vibration signature changesunder its standard operating conditions, theindication is that an impending defect is startingto change the machine’s mechanical condition.Different defects cause the vibration signature tochange in different ways; thus, the vibrationsignature provides a means of determining thesource of the problem as well as warning of theproblem itself.

Vibration Meter

The information that we provide on vibrationmeters is a general description of the meters.For information concerning operation of this

equipment, consult the manufacturer’s technicalmanual.

The basic instrument for a vibration preventivemaintenance program is the vibration meter.Figure 3-28 shows a typical vibration meter usedon board ships. This is a portable, handheld unitthat is used for periodic machinery checks. Itmeasures the overall vibration of a machine,which is essentially a summation of all thevibrations present in the machine at the measure-ment point.

The portable, battery-powered meter issupplied with a carrying case. This case holds theinstrument instruction manual, vibration pickup,4-foot pickup cable, 9-inch probe, magneticholder, magnetic shield, and meter carrying strap.

Vibration Analyzers

The vibration analyzer provides a vibrationmeasurement capability beyond that available inthe vibration meter. The vibration meter’sfunction is to determine the mechanical conditionof machinery by measuring overall vibrationamplitude. When the meter detects a mechanicaldefect, however, it is not capable of pinpointingthe specific cause. This is the purpose of thevibration analyzer.

A vibration analyzer (fig. 3-29) contains atunable filter and a stroboscopic light. You use

Figure 3-29.—Model 350 vibration analyzer.

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these to measure the vibration amplitude,frequency, and phase. These are the threevibration characteristics needed to describe andidentify any vibration.

PRESSURE TRANSDUCERCALIBRATION KIT

You will use the pressure transducer calibra-tion kit when performing maintenance on thevarious pressure transducers. The kit consists ofthree suitcase type of containers and a dualdiaphragm vacuum pump.

The absolute pressure calibration unit is in onecontainer. You will use this unit when calibratingthe absolute pressure transducers. The unit hastwo panel-mounted gauges, a high-pressureregulator, a vacuum/pressure regulator, and aselector valve. The three connection ports are forhigh-pressure supply, regulated pressure out, andvacuum source.

The gauge pressure and differential pressurecalibration unit is in another container. Use thisunit when you calibrate the gauge pressure anddifferential pressure transducers. The unit has

three panel-mounted gauges, a high-pressureregulator, and a selector valve.

The third container provides storage for themultimeter and leads, the nitrogen bottleregulator, and the hose assemblies. The nitrogenbottle is separate and does NOT come with the kit.

Before you calibrate any of the pressuretransducers, be sure the gauges on the calibrationunits do not require calibrating. For detailedinstructions, refer to Propulsion Gas TurbineModule LM2.500, Trouble Isolation, volume 2,part 3, S9234-AD-MMO-050/LM2500.

CENTRIFUGE

The centrifuge is used to conduct the BS&Wtest on fuel or to separate different liquids andsolids from liquids. The centrifuge (fig. 3-30)consists of a top piece from which four metal tubecarriers swing. The carrier holds glass centrifugetubes graduated to 100 ml. An electric motorrotates the top piece with the tubes. The centrifugehas an adjustable rheostat to select the speed.

To operate the centrifuge, place two tubes withthe 100 ml of fuel at opposite ends of the carrier.Then whirl them for 15 minutes at a speed of

Figure 3-30.—Centrifuge

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1,500 rpm. Read the combined volumeof water and sediment at the bottom of each tube.Readings from the tubes are a direct percentageof water and sediment. Determine the BS&Wof the fuel, add the readings from the two centrifugetubes, and divide by two.should repeat this operation until the volume ofwater and sediment in each tube remainsconstant for two consecutive readings. In general,you will not have to perform more than fourwhirlings.

PENSKY-MARTENS CLOSED-CUPFLASH POINT TESTER

The Pensky-Martens closed-cup flash pointtester determines the flash point of fuel receivedon board ship. Figure 3-31 shows the tester, which

contains a cup with a lid, a stirring device, athermometer, and a heat source.

The flash point of a petroleum product is thelowest temperature at which it gives off sufficientvapors to form a combustible mixture that canbe ignited momentarily. Knowledge of the flashpoint aids you in determining precautionarymeasures to take against fire and explosionhazards. A flash point substantially lower thanexpected is a reliable indication of contaminationwith a highly volatile product (such as aviationgasoline). Contamination of a product can lowerits flash point beyond safe handling and storageprocedures for that product. This test will alsoindicate dilution of the product by substances thatwill cause the flash point to be excessively high.The minimum flash point for all fuel on Navyships is 140°F.

Figure 3-31.—Pensky-Martens closed-cup flash point tester.

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FREE WATER DETECTOR

The Free Water Detector (FWD) (fig. 3-32) is a smallportable instrument that quantitatively determines

free or mechanically suspended water present inaircraft fuels. You can use it to test both navaldistillate and JP-5. The test procedures for thesetwo fuels differ as do the criteria the fuels mustmeet.

Figure 3-32.—A.E.L. Mk II.

Figure 3-33.—A.E.L. ML III.

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The FWD is a small aluminum boxcontaining an UV lamp source for viewingthe fluorescence resulting from the reactionof free water in the fuel with a chemical-impregnated test pad. Incorporated into the boxare the FWD components necessary for view-ing the fluorescence, including the UV lightmomentary switch, transformer, and test padholder slider.

CONTAMINATED FUELDETECTOR

The Contaminated Fuel Detector (CFD) (fig. 3-33) is a portableinstrument that determines the quantity of solidcontamination present in naval distillate and JP-5.You are required to have one CFD onboard for each type of fuel to maintain youroperation fuel quality assurance and aviationcertification.

The CFD consists of a fuel samplecontainer, a fuel-millepore filtration system (withthe filter), and a light transmission system todetermine the quantity of solid contamination ona millepore filter. It is reliable, accurate, andrugged. This fuel detector is capable of providinga quick determination of the quantity of solidcontaminates in fuels.

The contaminated fuel dectector is a self-contained unit. All components necessary forfiltration and measurement of transmitted lightare in one serviceable package. A drawer,compartments, and holders are available forstorage of filters, sampling bottles, filter holder,power cable, and vital spare parts.

RESISTANCE BOXES

At one time or another while performingmaintenance actions, you will use a resistance box,

sometimes called a decade box. Figure 3-34 showsan example of this box. These boxes, generallyoblong in shape, contain variable resistors. On topof the boxes you will see either four, five,or six rotary switches, depending on the type ofbox used. Each switch will have the numbers0 through 9 on it. Below each switch you willsee a number known as the multiplier. Threeterminals are on the right-hand side of the boxto connect it with the circuit(s). Some of the boxesmay also have a decimal point, such as betweenswitches (3) and (4) in figure 3-34.

The resistance boxes have different ohmicvalue designations. Printed on the top of the boxyou will find the upper limit. For example, a1-kilohm (KΩ) box will range from 0.01 to 999.99ohms, a 1-megohm (M Ω) box will range from1 to 999,999 ohms, and so forth.

Each rotary switch on the box controls its ownvariable resistor. These resistors are arranged sothat each resistor’s value can be collectively addedto each other. Using the figure and reading theswitches from left to right, (1) is in the hundredsplace, (2) is tens, (3) is ones, (4) is tenths, and (5)is hundredths. To determine the value of aresistor, such as (2) in the figure, read the dialsetting, which is 3, and its multiplier, which isRX10. This becomes 3R x 10 or 3 ohms x 10.Therefore, the value of resistor (2) is 30 ohms atthis setting. Calculate all of the other resistors inthe same manner. Then add the values of eachresistor together to get the total resistance of thebox. What is the total resistance of the box infigure 3-34? If you figured it out correctly, itwould be 730.19 ohms.

You will use these resistance boxes whenchecking the calibrations of equipment, such aspower turbine total inlet pressure (Pt 5.4) sensorsand various transducers.

Figure 3-34.—Decade resistance box.

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POWER SUPPLY

The power supply you will use is a portabledevice. You will use it to perform maintenanceor to check equipment operation. The powersupply ranges from 0 to 50 volts direct current(dc). This is more than adequate for the majorityof your work.

This type of power supply is simple and easyto use. On the front of the power supply are theoutput controls, a voltage meter, and the terminalconnections.

When using a power supply, make sure youfollow all safety precautions. Refer to themanufacturer’s technical manual for the proper

operating procedures. To avoid damaging theequipment you are working on, know its limitsand do not exceed them. When making connec-tions, be sure you observe proper polarity.

MULTIMETERS

During troubleshooting, you will often be re-quired to measure voltage, current, and resistance.Rather than using three or more separate metersfor these measurements, you can use the MULTI-METER. The multimeter contains circuitry thatallows it to function as a voltmeter, an ammeter,or an ohmmeter. A multimeter is often called aVOLT-OHM-MILLIAMMETER (vom).

Figure 3-35.—Simpson 260, volt-ohm-milliammeter (vom).

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The Simpson 260 multimeter (fig. 3-35) is atypical vom used in the Navy today. It has a metermovement for you to use to take the readings.You must look at the switches to determine whichscale to use on the meter. A disadvantage of thistype of vom is it tends to “load” the circuit undertest.

ELECTRONIC DIGITALMULTIMETERS

The electronic digital multimeter can do thesame job as the multimeter. The main differencebetween the two types of multimeters is theelectronic digital multimeter display is digital andit has a higher input impedance. Because of thehigher input impedance of the electronic digitalmultimeter, the loading effect is less and themeasurements taken are more accurate.

One example of a typical electronic digitalmultimeter in use within the Navy is the Model8000A electronic digital multimeter. Mostelectronic digital multimeters overcome thedisadvantage of requiring a continuous externalpower source by combining an external ac sourcewith an internal rechargeableshows the Model 8000Amultimeter.

MEGOHMMETER

battery. Figure 3-36electronic digital

You cannot use an ordinary ohmmeter formeasuring multimillion ohm values of resistances,such as those in conductor insulation. To test forsuch insulation breakdown, you need to use a

much higher potential than that supplied by thebattery of an ohmmeter. This potential is placedbetween the conductor and the outside of theinsulation. A megohmmeter (Megger) is used forthese tests. Figure 3-37 shows a portable megohm-meter with two main elements: (1) a hand-drivendc generator, which supplies the necessaryvoltage for making the measurement, and (2) theinstrument portion, which indicates the value ofthe resistance you are measuring.

OSCILLOSCOPES

Many different types of oscilloscopes areavailable. They vary from relatively simple testinstruments to highly accurate laboratory models.

Figure 3-37.—Megohmmeter.

Figure 3-36.—Digital voltmeter operating features.

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Figure 3-38 shows the front panel of a dual-trace,general-purpose oscilloscope. It is commonly usedin the fleet.

Oscilloscopes vary greatly in the numberof controls and connectors. Usually, the morecontrols and connectors, the more versatilethe instrument. Regardless of the number, alloscilloscopes have similar controls and con-nectors. Once you learn the fundamental opera-tion of these common controls, you can movewith relative ease from one model of oscillo-scope to another. Occasionally, controls thatserve similar functions will be differentlylabeled from one model to another. However, youwill find that most controls are logically groupedand that their names usually indicate theirfunction.

The oscilloscope in figure 3-38 is referred toas a DUAL-TRACE OSCILLOSCOPE. Itaccepts and displays two vertical signal inputs atthe same time—usually for comparison of the twosignals or one signal and a reference signal. Thisscope can also accept just one input. In this caseit is used as a SINGLE-TRACE OSCILLO-SCOPE.

SIGNAL GENERATORS

The many types of signal generators (oscil-lators) vary from relatively simple test instrumentsto highly accurate laboratory models. Theirfunction is to produce ac of the desired frequencyand amplitudes.

One of the primary uses of a signal generatoris to set power turbine (PT) speed trip set points.Figure 3-39 shows a typical wide-range oscillator.

FREQUENCY COUNTERS

Many different types of frequency countersare available. They vary from relatively simpletest instruments to highly accurate instruments.Frequency counters function to measure frequen-cies that already exist.

You can use a frequency counter in con-junction with the signal generator to check theoutput frequency of a signal generator for moreaccuracy.

HYDROMETER

You will be responsible for maintaining thebatteries for the uninterruptible power supply

Figure 3-38.—Dual-trace oscilloscope.

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Figure 3-39.—A typical wide-range oscillator.

(UPS). This section will not cover the batteries,but the tool required to check them. We willdiscuss batteries in chapters 9 and 10 of thismanual.

A hydrometer measures active ingredients inthe electrolyte of the battery. The hydrometermeasures the SPECIFIC GRAVlTY of theelectrolyte. Specific gravity is the ratio of theweight of the electrolyte to the weight of the samevolume of pure water. The electrolyte’s activeingredients, such as sulfuric acid or potassiumhydroxide, are heavier than water. Because theactive ingredient is heavier than water, the moreactive ingredient there is in the electrolyte, theheavier the electrolyte will be; the heavier theelectrolyte, the higher the specific gravity.

A hydrometer (fig. 3-40) is a glass syringe witha float inside it. The float is a sealed, hollow glasstube weighted at one end. Marked on the side ofthe float is a scale calibrated in specific gravity.Use the suction bulb to draw the electrolyte intothe hydrometer. Make sure enough electrolyte isdrawn into the hydrometer for the float to rise.

Figure 3-40.—Hydrometer.

Do not fill the hydrometer too much so that thefloat rises into the suction bulb.

Since the weight of the float is at its base, thefloat will rise to a point determined by the weightof the electrolyte. If the electrolyte has a largeconcentration of active ingredient, the float willrise higher than if the electrolyte has a smallconcentration of active ingredient.

To read the hydrometer, hold it in a verticalposition and take the reading at the level of theelectrolyte. Refer to the manufacturer’s technicalmanual for battery specifications for the correctspecific gravity ranges.

NOTE: Flush hydrometers with freshwater after each use to prevent inaccuratereadings. Do not use storage batteryhydrometers for any other purpose.

3-29

When working with batteries, ensure you wearproper protective clothing (such as safety glasses,rubber gloves, rubber apron, and rubber boots).The battery water contains acids which can ruinclothes and cause severe burning. Be sure youfollow the safety precautions found in NavalShips’ Technical Manual, Chapter 313, “PortableStorage and Dry Batteries,” and those found onthe PMS card.

HOISTING AND LIFTING DEVICES

When performing maintenance, you may haveto move or lift some of the heavy equipment orcomponents. You can use various devices to dothis. The selection of the proper device dependson many factors, such as the equipment to bemoved and the available work space. A workingknowledge of the following devices will aid youin selecting the right device.

CHAIN HOISTS

Chain hoists (chain falls) provide an easy andefficient method for hoisting loads by hand. Theadvantages of chain hoists are that one person canraise a load of several tons, and the load canremain stationary without being secured. A chainhoist permits small movements, accurate adjust-ment of height, and gentle handling of loads.For these reasons they are particularly usefulin hoisting motors or parts which must beprecisely aligned with other parts. Two of themost common types used for vertical hoistingoperations are the differential chain hoist and thespur gear hoist (fig. 3-41). The load capacity ofa chain hoist can range from 1/2 ton to 40 tonsand is stamped on the shell of the upper block.

The differential chain hoist is suitable for lightloads. This hoist is only about 35 percent efficient.In other words, about 35 percent of the energythat you exert is converted into useful work forlifting the load. The remaining 65 percent of theenergy is spent in overcoming friction in the gears,bearings, and chains.

The spur gear hoist is used for operations thatrequire frequent use of a hoist and where fewpersonnel are available to operate it. The spur gearhoist is about 85 percent efficient.

The lower hook is usually the weakest part inthe assembly of a chain hoist. This is intended asa safety measure so the hook will start to spreadopen if overloaded. Thus, you must closely watchthe hook to detect any sign of overloading in timeto prevent damage.

Figure 3-41.—Chain hoists.

Before using a chain hoist, inspect it toensure safe operation. Replace a hook that showssigns of spreading or excessive wear. If links inthe chain are distorted, the chain hoist hasprobably been overloaded. Make sure the hoistis in good repair before attempting to lift a load.

HAND-OPERATED RATCHETLEVER HOISTS

Hand-operated ratchet lever hoists (fig. 3-42),more commonly called come-a-longs, are similarto the chain hoist. The main difference is that youoperate a ratchet handle to move the load vice achain. The direction of movement is changed bya lever on the side of the unit or in the handle.

Compared to the chain hoist, the come-a-longis smaller because of the size difference of the top

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portion of the units. The come-a-long is used inmaintenance as is the chain hoist; however,because the ratchet mechanism does not allow forminimal movements, it is NOT recommended foruse in the alignment of parts.

PUSH-PULL HYDRAULIC JACK

A push-pull hydraulic jack, commonly calleda port-a-power, consists of a pump and ramconnected by a flexible hose (fig. 3-43). Jacks of

Figure 3-42.—Hand-operated ratchet lever hoist (come-a-long).

Figure 3-43.—Push-pull hydraulic jack (port-a-power).

3-31

this type are rated at 2-, 7-, 20-, 30-, and 100-toncapacities and have diversified applications. Thesejacks are furnished with an assortment ofattachments. These attachments enable you toperform countless pushing, pulling, lifting, press-ing, bending, spreading, and clamping operations.The pump is hand operated. A flexible hydraulichose allows you to operate the ram in any desiredposition and from a safe distance. You can retractthe ram automatically by turning a single controlvalve.

When using the port-a-power to raise a part,make certain no one is under the part. Keepfingers away from all moving parts. Be sure toplace blocking or other supports under the partwhen it is raised to the desired height to preventit from dropping if the jack fails. Before usinga hydraulic jack of any type, make sure it is filledwith fluid and has no apparent leaks.

CRANES

As a general rule, the cranes you use arelocated pierside. The crane is used when equip-ment must be moved to a pierside facility, suchas a shore intermediate maintenance activity(SIMA), for overhaul. The ship’s personnelgenerally moves any equipment to the main deckof your ship, and then the crane operator off-loads it. Obviously, when removing a GTE, theship’s personnel do not move the engine topside.In this situation, the crane drops its hook downthe inlet plenum of the GTE. Special rails areinstalled in the inlet plenum to facilitate theremoval.

NOTE: Before you use any of the hoistingand lifting devices, ensure that they are ingood working order. If you use beamclamps, C-clamps, or wire straps, makesure they are secured properly and in goodcondition before attaching the liftingdevices to them.

SUMMARY

In this chapter we have introduced you tosome of the tools and test equipment that you willuse during maintenance or while performingoperational checks. We have not coveredall of the equipment you will use becauseeither you are already familiar with themor they are specialized equipment for use inspecific instances. One example of this specializedequipment is the special support equipment forthe LM2500 GTE. NAVSEA Technical ManualS9234-AA-MMA-000/LM2500 covers the specialequipment used in conjunction with the LM2500GTE. It will provide you with a good descriptionof the function of this equipment.

You will find that an in-depth knowledge oftest equipment is especially useful introubleshooting equipment problems, and anunderstanding of the use of the correct tools atthe proper time will make you a more efficienttechnician. Remember, for further informationrefer to Use and Care of Hand Tools and Measuring Tools,NAVEDTRA 12085, and Navy Electricity and ElectronicsTraining Series (NEETS), modules 1, 3, and 16.You should also consult each equipment’stechnical manual for the correct test equipmentoperation and proper use.

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CHAPTER 4

ELECTRICAL THEORYAND MECHANICAL THEORY

In this chapter we will discuss electrical theoryand mechanical theory and how you will use thesetheories in the everyday performance of yourassigned tasks. During our discussion we willdemonstrate a few examples of the theories thatare pertinent and/or necessary to you at yourlevel of training. You need to understand thebasic laws and principles of electrical theory andmechanical theory to form a foundation for thefurther development of your knowledge. Itis our intention to ensure you understand thebasics before you attempt the practical applicationof these theories. The practical application ofelectrical theory and mechanical theory will bediscussed in later chapters. To fully grasp andunderstand the laws and principles discussed inthis chapter, you should be familiar with theknowledge provided in the NEETS trainingmodules 1 through 5 and Basic Machines,NAVEDTRA 10624-A.

After studying this chapter, you should be ableto (1) state the pertinent laws and principles ofelectrical theory (Ohm’s, Kirchhoff’s, Coulomb’s,and the law of magnetism); (2) recognize therequirements needed to produce and the variousmethods used for electric power generation; (3)state the basic laws and principles of mechanicaltheory (Charles’s, Boyle’s, Pascal’s, and Newton’sfirst, second, and third laws, and Bernoulli’sprinciple); (4) describe energy and explain itsdifferent forms; (5) relate the theory of leverageto the moving and lifting of objects; (6) recognizethe different temperature scales and pointout their relationship to each other; and(7) identify the different types of pressure (gauge,atmospheric, barometric, and absolute) and pointout their relationship to each other.

ELECTRICAL THEORY

Electrical theory is just that, THEORY.Presently, little more is known than the ancientGreeks knew about the fundamental nature of

electricity, but tremendous strides have been madein harnessing and using it. Elaborate theoriesconcerning the nature and behavior of electricityhave been advanced and have gained wideacceptance because of their apparent truth anddemonstrated workability.

LAWS

By learning the rules and laws applying to thebehavior of electricity and by understanding themethods used to produce and control electricity,you may learn about electricity without everhaving determined its fundamental identity. Yourpersistence and ability to sort out facts and askdetailed questions will determine how thoroughlyyou understand electrical theory and laws,and how they pertain to you. For an indepthdiscussion of the basic laws of electricity, youshould study NEETS, module 1.

Ohm’s Law

In the early part of the nineteenth century,George Simon Ohm proved by experiment thata precise relationship exists between current,voltage, and resistance. This relationship is calledOhm’s law. It states that

the current in a circuit is DIRECTLYproportional to the applied voltage andINVERSELY proportional to the circuitresistance.

Simply stated, this means that as the resistancein a circuit increases, the current decreasesproportionally.

Kirchhoff’s Voltage Law

In 1847, G. R. Kirchhoff extended the use ofOhm’s law by developing a simple concept

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concerning the voltages contained in a series loop.Kirchhoff’s law states that

the algebraic sum of the voltage drops inany closed path in a circuit and theelectromotive forces in that path are equalto zero.

To state Kirchhoff’s law another way, thevoltage drops and voltage sources in a circuit areequal at any given moment in time. If the voltagesources are assumed to have one sign (positive ornegative) at that instant and the voltage drops areassumed to have the opposite sign, the result ofadding the voltage sources and voltage drops willbe zero. For more detailed information on the useand application of Kirchhoff’s law, refer tochapter 3 of NEETS, module 1.

NOTE: In applying Kirchhoff’s law todirect current (dc) circuits, the termelectromotive force (emf) applies to voltagesources, such as batteries or powersupplies. Kirchhoff’s law is also used inalternating current (ac) circuits (which arecovered in NEETS, module 2).

Coulomb’s Law

The relationship between attracting orrepelling charged bodies was first discovered bya French scientist named Charles A. Coulomb.Coulomb’s law states that

charged bodies attract or repel each otherwith a force that is directly proportionalto the product of their individual charges,and is inversely proportional to the squareof the distance between them.

Simply stated, the amount of attracting orrepelling force which acts between two electricallycharged bodies in free space depends on twothings-(l) their charges and (2) the distancebetween them.

Law of Magnetism

To properly understand the principles ofelectricity, you need to understand magnetism andthe effects of magnetism on electrical equipment.Magnetism and electricity are so closely relatedthat knowledge of either subject would beincomplete without at least a basic knowledge ofthe other.

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Much of today’s modern electrical andelectronic equipment could not function withoutmagnetism. Modern computers, tape recorders,and video reproduction equipment use magnetizedtape and/or discs. High-fidelity speakers usemagnets to convert amplifier outputs into audiblesound. Electrical motors use magnets to convertelectrical energy into mechanical motion;generators use magnets to convert mechanicalmotion into electrical energy. Simply stated, thelaw of magnetism states that

like poles repel, unlike poles attract.

MAGNETIC FIELDS.—The space surround-ing a magnet where magnetic forces act is knownas the magnetic field. You can prove that themagnetic field is very strong at the poles andweakens as the distance from the poles increasesby conducting simple experiments. It will also beapparent that the magnetic field extends from onepole to the other, constituting a loop about themagnet.

Although magnetic lines of force are im-aginary, a simplified version of many magneticphenomena can be explained by assuming themagnetic lines to have certain real properties. Thelines of force can be compared to rubber bands,which stretch outward when a force is exertedupon them and contract when the force isremoved. The characteristics of magnetic lines offorce can be described as follows:

1. Magnetic lines of force are continuous andwill always form closed loops.

2. Magnetic lines of force will never cross oneanother.

3. Parallel magnetic lines of force travelingin the same direction repel one another. Parallelmagnetic lines of force traveling in oppositedirections tend to unite with each other and forminto single lines traveling in a direction determinedby the magnetic poles creating the lines of force.

4. Magnetic lines of force tend to shortenthemselves. Therefore, the magnetic lines of forceexisting between two unlike poles cause the polesto be pulled together.

5. Magnetic lines of force pass through allmaterials, both magnetic and nonmagnetic.

6. Magnetic lines of force always enter orleave a magnetic material at right angles to thesurface.

MAGNETIC EFFECTS.—The total numberof magnetic lines of force leaving or entering the

pole of a magnet is called the MAGNETICFLUX. The number of flux lines per unit area isknown as FLUX DENSITY. The intensity of amagnetic field is directly related to the magneticforce exerted by the field. The force between twopoles is directly proportional to the product ofthe pole strengths and inversely proportional tothe square of the distance between the two poles.

Magnetism can be induced in a magneticmaterial by several means. The magnetic materialmay be placed in the magnetic field, broughtinto contact with a magnet, or stroked by amagnet. Stroking and contact both indicateactual contact with the material but are consideredin magnetic studies as magnetizing byINDUCTION.

MAGNETIC SHIELDING.—There is noknown INSULATOR for magnetic flux. If a non-magnetic material is placed in a magnetic field,there is no appreciable change in flux-that is,the flux penetrates the nonmagnetic material. Ifa magnetic material (for example, soft iron) isplaced in a magnetic field, the flux may beredirected to take advantage of the greaterpermeability of the magnetic material, as shownin figure 4-1. Permeability is the quality of asubstance that determines the ease with which itcan be magnetized.

The sensitive mechanisms of electric instru-ments and meters can be influenced by straymagnetic fields, which will cause errors in theirreadings. Because instrument mechanisms cannotbe insulated against magnetic flux, it is necessaryto employ some means of directing the fluxaround the instrument. This is accomplished byplacing a soft-iron case, called a MAGNETICSCREEN or SHIELD, about the instrument.Because the flux is established more readilythrough the iron (even though the path is longer)

Figure 4-1.—Effects of a magnetic substance in a magneticfield.

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than through the air inside the case, the instru-ment is effectively shielded, as shown by the watchand soft-iron shield in figure 4-2.

For further information on magnetism, youshould refer to NEETS, module 1.

ELECTRICAL POWER GENERATION

A generator is a machine that convertsmechanical energy to electrical energy using theprinciple of magnetic induction. This principle isbased on the fact that

if a conductor is moved within a magneticfield in such a way that the conductor cutsacross magnetic lines of force, voltage isgenerated in the conductor.

The AMOUNT of voltage generated dependson (1) the strength of the magnetic field, (2) theangle at which the conductor cuts the magneticfield, (3) the speed at which the conductor ismoved, and (4) the length of the conductor withinthe magnetic field.

The POLARITY of the voltage dependson the direction of the magnetic lines offlux and the direction of movement of theconductor.

Figure 4-2.—Magnetic shield.

Methods of Producing Electrical Power

The following is a list of the six most commonmethods of producing emf. Some of thesemethods are much more widely used than others.We will first define the methods for you, and thenwe will discuss them in more detail.

1. MAGNETISM—Voltage produced in aconductor when the conductor moves through amagnetic field, or when a magnetic field movesthrough the conductor in such a manner as to cutthe magnetic lines of force of the field.

2. FRICTION—Voltage produced by rubbingtwo materials together.

3. PRESSURE (piezoelectricity)—Voltageproduced by squeezing crystals of certainsubstances.

4. HEAT (thermoelectricity)—Voltage pro-duced by heating the joint (junction) where twounlike metals are joined.

5. LIGHT (photoelectricity)—Voltage pro-duced by light striking photosensitive (lightsensitive) substances.

6. CHEMICAL ACTION—Voltage pro-

VOLTAGE PRODUCED BY MAGNET-ISM.—Magnets or magnetic devices are used forthousands of different jobs. One of the mostuseful and widely employed applications ofmagnets is in the production of vast quantities ofelectric power from mechanical sources. Themechanical power may be provided by a numberof different sources, such as gasoline or dieselengines and water or steam turbines. However,the final conversion of these source energies toelectricity is done by generators employing theprinciple of electromagnetic induction. We willdiscuss here the fundamental operating principleof all such electromagnetic induction generators.

To begin with, three fundamental conditionsmust exist before a voltage can be produced bymagnetism. These conditions are

1. a CONDUCTOR, in which the voltage willbe produced,

2. a MAGNETIC FIELD in the conductor’svicinity, and

3. a RELATIVE MOTION between the fieldand the conductor. The conductor must be movedso as to cut across the magnetic lines of force, orthe field must be moved so that the lines of force

duced by chemical reaction in a battery cell. are cut by the conductor.

Figure 4-3.—Voltage produced by magnetism.

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According to these conditions, when a con-ductor or conductors move across a magnetic fieldso as to cut the lines of force, electrons within theconductor are impelled in one direction oranother. Thus, an electric force, or voltage, iscreated.

In figure 4-3, note the presence of the threeconditions needed for creating an induced voltage:

1. There is a conductor (copper wire).

2. There is a magnetic field between the polesof the C-shaped magnet.

3. There is relative motion. The wire is movedback and forth ACROSS the magneticfield.

In figure 4-3, view A, the conductor ismoving TOWARD the front of the page. Theright-hand end becomes negative, and the left-hand end becomes positive. This occurs becauseof the magnetically induced emf acting on theelectrons in the copper. The conductor isstopped, view B, motion is eliminated (one of thethree required conditions), and there is no longeran induced emf. Consequently, there is no longerany difference in potential between the two endsof the wire. The conductor at view C is movingaway from the front of the page. An induced emfis again created. However, note carefully thatthe REVERSAL OF MOTION has caused aREVERSAL OF DIRECTION in the inducedemf.

If a path for electron flow is provided betweenthe ends of the conductor, electrons will leave thenegative end and flow to the positive end. Thiscondition is shown in view D. Electron flow willcontinue as long as the emf exists. In studyingfigure 4-3, note that the induced emf could alsohave been created by holding the conductorstationary and moving the magnetic field back andforth.

VOLTAGE PRODUCED BY FRICTION.—This is the least used of the six methods ofproducing voltages. Its main application is in Vande Graf generators, used by some laboratories toproduce high voltages. As a rule, frictionelectricity (often referred to as static electricity)is a nuisance. For instance, a flying aircraftaccumulates electric charges from the ‘frictionbetween its skin and the passing air. These chargesoften interfere with radio communication, and

under some other circumstances can even causephysical damage to the aircraft. Most individualsare familiar with static electricity and haveprobably received unpleasant shocks fromfriction electricity upon sliding across dry seatcovers or walking across dry carpets, and thencoming in contact with some other object.

VOLTAGE PRODUCED BY PRESSURE.—This action is referred to as piezoelectricity. It isproduced by compressing or decompressingcrystals of certain substances. To study this formof electricity, the meaning of the word crystalmust first be understood. In a crystal, themolecules are arranged in an orderly and uniformmanner. Figure 4-4 shows a substance in its non-crystallized state and its crystallized state.

For the sake of simplicity, assume that themolecules of this particular substance are spherical(ball-shaped). In the noncrystallized state, viewA, note that the molecules are arrangedirregularly. In the crystallized state, view B, themolecules are arranged in a regular and uniformmanner. This illustrates the major physicaldifference between crystal and noncrystal formsof matter. Natural crystalline matter is rare; anexample of matter that is crystalline in its naturalform is diamond, which is crystalline carbon.Most crystals are manufactured.

Crystals of certain substances, such asRochelle salt or quartz, exhibit peculiar electricalcharacteristics. These characteristics, or effects,are referred to as piezoelectric. For instance,when a crystal of quartz is compressed, as in

Figure 4-4.—Molecules of noncrystallized and crystallizedmatter.

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figure 4-5, view A, electrons tend to move throughthe crystal as shown. This tendency creates anelectrical difference of potential between the twoopposite faces of the crystal. (The fundamentalreasons for this action are not known. However,the action is predictable, and therefore useful.)If an external wire is connected while the pressureand emf are present, electrons will flow. If thepressure is held constant, the electron flow willcontinue until the charges are equalized. When

Figure 4-5.—Quartz crystal. A. Compressed. B. De-compressed.

the force is removed, the crystal is decompressedand immediately causes an electric force in theopposite direction, view B. Thus, the crystal isable to convert mechanical force, either pressureor tension, to electrical force.

The power capacity of a crystal is extremelysmall. However, they are useful because of theirextreme sensitivity to changes of mechanical forceor changes in temperature. Due to othercharacteristics not mentioned here, crystals aremost widely used in communication equipment.

VOLTAGE PRODUCED BY HEAT.—When a length of metal, such as copper, is heatedat one end, electrons tend to move away from thehot end toward the cooler end. This is true of mostmetals. However, in some metals, such as iron,the opposite takes place and electrons tend tomove TOWARD the hot end. Figure 4-6 showsthis characteristic. The negative charges (electrons)are moving through the copper away from theheat and through the iron toward the heat. Theycross from the iron to the copper at the hotjunction and from the copper through thecurrent meter to the iron at the cold junction. Thisdevice is generally referred to as a thermocouple.

Thermocouples have somewhat greater powercapacities than crystals, but their capacity is stillvery small if compared to some other sources. Thethermoelectric voltage in a thermocouple dependsmainly on the difference in temperature between

Figure 4-6.—Voltage produced by heat.

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the hot and cold junctions. Consequently, theyare widely used to measure temperature and asheat-sensing devices in automatic tempereraturecontrol equipment. Thermocouples generally canbe subjected to much greater temperatures thanordinary thermometers, such as the mercury oralcohol types.

VOLTAGE PRODUCED BY LIGHT.—When light strikes the surface of a substance, itmay dislodge electrons from their orbits aroundthe surface atoms of the substance. This occursbecause the light has energy, the same as anymoving force.

Some substances, mostly metallic ones, are farmore sensitive to light than others. That is, moreelectrons will be dislodged and emitted from thesurface of a highly sensitive metal, with a givenamount of light, than will be emitted from a lesssensitive substance. Upon losing electrons, thephotosensitive (light sensitive) metal becomespositively charged, and an electric force is created.Voltage produced in this manner is referred to asa photoelectric voltage.

The photosensitive materials most commonlyused to produce a photoelectric voltage are variouscompounds of silver oxide or copper oxide. Acomplete device that operates on the photo-electric principle is referred to as a photoelectriccell. Many sizes and types of photoelectric cellsare in use, each of which serves the specialpurpose for which it was designed. Nearly all,however, have some of the basic features of thephotoelectric cells shown in figure 4-7.

The cell (fig. 4-7, view A) has a curved light-sensitive surface focused on the central anode.When light from the direction shown strikes thesensitive surface, it emits electrons toward theanode. The more intense the light, the greater isthe number of electrons emitted. When a wire isconnected between the filament and the back, ordark side, the accumulated electrons will flow tothe dark side. These electrons will eventually passthrough the metal of the reflector and replace theelectrons leaving the light-sensitive surface. Thus,light energy is converted to a flow of electrons,and a usable current is developed.

The cell (fig. 4-7, view B) is constructed inlayers. A base plate of pure copper is coated withlight-sensitive copper oxide. An additionalsemitransparent layer of metal is placed over the

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Figure 4-7.—Voltage produced by light.

copper oxide. This additional layer serves twopurposes:

1. It is EXTREMELY thin to permit thepenetration of light to the copper oxide.

2. It also accumulates the electrons emittedby the copper oxide.

An externally connected wire completes theelectron path, the same as in the reflector typeof cell. The photocell’s voltage is used as neededby connection of the external wires to some otherdevice, which amplifies (enlarges) it to a usablelevel.

A photocell’s power capacity is very small.However, it reacts to light-intensity variations ina very short time. This characteristic makes thephotocell very useful in detecting or accuratelycontrolling a great number of processes oroperations. For instance, the photoelectriccell, or some form of the photoelectric principle,is used in television cameras, automaticmanufacturing process controls, door openers,burglar alarms, and so forth.

VOLTAGE PRODUCED BY CHEMICALACTION .— Up to this point, it has been shown

that electrons may be removed from their parentatoms and set in motion by energy derived froma source of magnetism, friction, pressure, heat,or light. In general, these forms of energy do notalter the molecules of the substance being actedupon. That is, molecules are not usually added,taken away, or split up when subjected to thesefour forms of energy. Only electrons are involved.

When the molecules of a substance are altered,the action is referred to as CHEMICAL. Forinstance, if the molecules of a substance combineswith atoms of another substance, or gives upatoms of its own, the action is chemical in nature.Such action always changes the chemical nameand characteristics of the substance affected. Forinstance, when atoms of oxygen from the air comein contact with bare iron, they merge with themolecules of iron. This iron is oxidized. Ithas changed chemically from iron to iron oxide,or rust. Its molecules have been altered bychemical action.

In some cases, when atoms are added to ortaken away from the molecules of a substance,the chemical change will cause the substance totake on an electric charge. The process ofproducing a voltage by chemical action is used inbatteries.

Left-Hand Rule For Generators

In the preceding section we gave you a basicoverview of voltage generation. This section willexplain and demonstrate the left-hand rule forgenerators.

The left-hand rule for generators is a goodrepresentation of the relationships betweenmotion, magnetic force, and resultant current inthe generation of a voltage. By using this rule,you may find any of the three quantities if theother two are known. This rule is explained in thefollowing manner.

Extend the thumb, forefinger, and middlefinger of your left hand at right angles to oneanother, as shown in figure 4-8. Point your thumbin the direction the conductor is being moved.Point your forefinger in the direction of magneticflux (from north to south). Your middle fingerwill then point in the direction of current flow inan external circuit to which the voltage is applied.

The more complex aspects of power genera-tion by use of mechanical motion and magnetismare discussed indepth in module 5 of the NEETSseries.

Figure 4-8.—Left-hand rule for generators.

MECHANICAL THEORY

To understand basic mechanical theory, youmust be familiar with the physics concepts used.In the following paragraphs we will discuss someof the laws and principles that will enable you tobetter understand these concepts.

LAWS AND PRINCIPLES

In this section we will first define, and thenexplain, the basic laws and principles ofmechanical theory.

CHARLES’S LAW: If the pressure isconstant, the volume of an enclosed dry gas variesdirectly with the absolute temperature.

BOYLE’S LAW: The volume of anenclosed gas varies inversely with the appliedpressure, provided the temperature remainsconstant.

NEWTON’S LAWS: The first law statesthat a body at rest tends to remain at rest. A bodyin motion tends to remain in motion. The secondlaw states that an imbalance of force on a bodytends to produce an acceleration in the directionof the force. The acceleration, if any, is directlyproportional to the force and inversely pro-portional to the mass of the body. Newton’s thirdlaw states that for every action there is an equaland opposite reaction.

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PASCAL’S LAW: Pressure exerted at anypoint upon an enclosed liquid is transmittedundiminished in all directions.

BERNOULLI’S PRINCIPLE: If anincompressible fluid flowing through a tubereaches a constriction, or narrowing of thetube, the velocity of fluid flowing through theconstriction increases and the pressure decreases.

Charles’s Law

Jacques Charles, a French scientist, providedmuch of the foundation for the modern kinetictheory of gases. He found that, if the pressureis held constant, all gases expand and contract indirect proportion to the change in the absolutetemperature. Any change in the temperature ofa gas causes a corresponding change in volume.Therefore, if a given sample of a gas were heatedwhile confined within a given volume, the pressureshould increase. Actual experiments found thatfor each 1°C increase in temperature, the increasein pressure was about l/273 of the pressure at0°C. Thus, it is normal practice to state thisrelationship in terms of absolute temperature. Inequation form, this part of the law becomes

P1T2 = P2T1,

where

P = pressure, and

T = temperature.

In words, this equation states that with aconstant volume, the absolute pressure of anenclosed gas varies directly with the absolutetemperature. Remember, when using this for-mula, you must convert stated pressures andtemperatures to absolute values.

Boyle’s Law

Compressibility is an outstanding charac-teristic of gases. Robert Boyle, an Englishscientist, was among the first to study thischaracteristic. He called it the “springiness” ofair. He discovered that when the temperature ofan enclosed sample of gas was kept constant andthe pressure doubled, the volume was reduced tohalf the former value. As the applied pressure wasdecreased, the resulting volume increased. From

these observations he concluded that for aconstant temperature the product of the volumeand pressure of an enclosed gas remains constant.This conclusion became Boyle’s law.

You can demonstrate Boyle’s law by confininga quantity of gas in a cylinder that has a tightlyfitted piston. Apply force to the piston so as tocompress the gas in the cylinder to some specificvolume. If you double the force applied to thepiston, the gas will compress to one half itsoriginal volume (fig. 4-9).

Changes in the pressure of a gas also affectthe density. As the pressure increases, its volumedecreases; however, there is no change in theweight of the gas. Therefore, the weight per unitvolume (density) increases. So it follows that thedensity of a gas varies directly with the pressure ifthe temperature is constant.

Newton’s Laws

Sir Isaac Newton was an English philosopherand mathematician who lived from 1642 to 1727A.D. He was the formulator of the basic laws ofmodern philosophy concerning gravity andmotion.

NEWTON’S FIRST LAW.—Newton’s firstlaw states that a body at rest tends to remain atrest. A body in motion tends to remain inmotion. This law can be demonstrated easily ineveryday use. For example, a parked automobilewill remain motionless until some force causes itto move-a body at rest tends to remain at rest.The second portion of the law-a body inmotion tends to remain in motion-can bedemonstrated only in a theoretical sense. Thesame car placed in motion would remain in

Figure 4-9.—Gas compressed to half its original volume bya double force.

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motion (1) if all air resistance were removed,(2) if no friction were in the bearings, and (3) ifthe surface were perfectly level.

NEWTON’S SECOND LAW.—Newton’ssecond law states that an imbalance of force ona body tends to produce an acceleration in thedirection of the force. The acceleration, if any,is directly proportional to the force. It is inverselyproportional to the mass of the body. This lawcan be explained by throwing a common softball.The force required to accelerate the ball to a rateof 50 ft/sec2 would have to be doubled to obtainan acceleration rate of 100 ft/sec2. However, ifthe mass of the ball were doubled, the originalacceleration rate would be cut in half. You wouldhave 50 ft/sec2 reduced to 25 ft/sec2.

NEWTON’S THIRD LAW.-—Newton’s thirdlaw states that for every action there is an equaland opposite reaction. You have demonstratedthis law if you have ever jumped from a boat upto a dock or a beach. The boat moved oppositeto the direction you jumped. The recoil fromfiring a shotgun is another example of action-reaction. Figure 4-10 depicts these examples.

In an airplane, the greater the mass of airhandled by the engine, the more it is acceleratedby the engine. The force built up to thrust theplane forward is also greater. In a gas turbine,the thrust velocity can be absorbed by the turbinerotor and converted to mechanical energy. Thisis done by adding more and progressively largerpower turbine wheels.

Pascal’s Law

Blaise Pascal was a French philosopher andmathematician who lived from 1623 to 1662 A.D.His work, simply stated, could be interpreted aspressure exerted at any point upon an enclosedliquid is transmitted undiminished in alldirections.

Pascal’s law governs the BEHAVIOR of thestatic factors concerning noncompressible fluidswhen taken by themselves.

Bernoulli’s Principle

Jacques (or Jakob) Bernoulli was a Swissphilosopher and mathematician who livedfrom 1654 to 1705 A.D. He worked extensivelywith hydraulics and the pressure-temperaturerelationship. Bernoulli’s principle governs theRELATIONSHIP of the static and dynamic

Figure 4-10.—Newton’s third law of motion.

factors concerning noncompressible fluids.Consider the system shown in figure 4-11.Chamber A is under pressure and is connectedby a tube to chamber B, which is also underpressure. Chamber A is under static pressureof 100 psi. The pressure at some point, X,along the connecting tube consists of a velocitypressure of 10 psi. This is exerted in a directionparallel to the line of flow. Added is theunused static pressure of 90 psi, which obeysPascal’s law and operates equally in all directions.As the fluid enters chamber B from theconstricted space, it is slowed down. In sodoing, its velocity head is changed back topressure head. The force required to absorbthe fluid’s inertia equals the force required tostart the fluid moving originally. Therefore, thestatic pressure in chamber B is again equal tothat in chamber A. It was lower at intermediatepoint X.

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Figure 4-11.—Relationship of static and dynamic factors—Bernoulli’s principle.

Figure 4-11 disregards friction and it is notencountered in actual practice. Force or head isalso required to overcome friction. But, unlikeinertia effect, this force cannot be recovered againalthough the energy represented still existssomewhere as heat. Therefore, in an actual systemthe pressure in chamber B would be less than inchamber A. This is a result of the amount ofpressure used in overcoming friction along theway.

At all points in a system the static pressure isalways the original static pressure LESS anyvelocity head at the point in question. It is alsoLESS the friction head consumed in reaching thatpoint. Both velocity head and friction representenergy that came from the original static head.Energy cannot be destroyed. So, the sum of thestatic head, velocity head, and friction at anypoint in the system must add up to the originalstatic head. This, then, is Bernoulli’s principle;more simply stated, if a noncompressible fluidflowing through a tube reaches a constriction, ornarrowing of the tube, the velocity of fluid flow-ing through the constriction increases, and thepressure decreases.

ENERGY

Can you define energy? Although everyonehas a general idea of the meaning of energy, agood definition is hard to find. Most commonly,perhaps, energy is defined as the capacity fordoing work. This is not a very completedefinition. Energy can produce other effects whichcannot possibly be considered work. For example,heat can flow from one object to another withoutdoing work; yet heat is a form of energy, and theprocess of heat transfer is a process that producesan effect.

A better definition of energy, therefore, statesthat energy is the capacity for producing an effect.

Energy exists in many forms. For convenience,we usually classify energy according to the sizeand nature of the bodies or particles with whichit is associated. Thus we say that MECHANICALENERGY is the energy associated with largebodies or objects-usually, things that are bigenough to see. THERMAL ENERGY is energyassociated with molecules. Chemical energy isenergy that arises from the forces that bind theatoms together in a molecule. Chemical energyis demonstrated whenever combustion or anyother chemical reaction takes place. Electricalenergy, light, X rays, and radio waves areexamples of energy associated with particles thatare even smaller than atoms.

Each of these types of energy (mechanicalenergy, thermal energy, and so forth) must alsobe classified as being either stored energy orenergy in transition.

STORED ENERGY can be thought of asenergy that is actually contained in or stored ina substance or system. There are two kinds ofstored energy: (1) potential energy and (2) kineticenergy. When energy is stored in a substance orsystem because of the relative POSITIONS of twoor more objects or particles, we call it potentialenergy. When energy is stored in a substance orsystem because of the relative VELOCITIES oftwo or more objects or particles, we call it kineticenergy.

If you do not completely understand thisclassification, come back to it from time to timeas you read the following sections on mechanicalenergy and thermal energy. The examples anddiscussion given in the following sections willprobably help you understand this classification.

Mechanical Energy

Let’s consider the two stored forms ofmechanical energy. Mechanical POTENTIALenergy exists because of the relative positions oftwo or more objects. For example, a rock restingon the edge of a cliff in such a position that itwill fall freely if pushed has mechanicalpotential energy. Water at the top of a dam hasmechanical potential energy. A sled that is beingheld at the top of an icy hill has mechanicalpotential energy.

Mechanical KINETIC energy exists becauseof the relative velocities of two or more objects.If you push that rock, open the gate of the dam,or let go of the sled, something will move. Therock will fall; the water will flow; the sled will slidedown the hill. In each case the mechanical

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potential energy will be changed to mechanicalkinetic energy. Another way of saying this is thatthe energy of position will be changed to theenergy of motion.

In these examples, you will notice that anexternal source of energy is used to get thingsstarted. Energy from some outside source isrequired to push the rock, open the gate of thedam, or let go of the sled. All real machines andprocesses require this kind of boost from anenergy source outside the system. For example,there is a tremendous amount of chemical energystored in fuel oil; but this energy will not turn thepower turbine until you have expended someenergy to start the oil burning. Similarly, theenergy in any one system affects other energysystems. However, it is easier to learn the basicprinciples of energy if we forget about all theenergy systems that might be involved in oraffected by each energy process. In the examplesgiven in this chapter, therefore, we will consideronly one energy process or energy system at atime, disregarding both the energy boosts thatmay be received from outside systems and theenergy transfers that may take place between thesystem we are considering and other systems.

Notice that both mechanical potential energyand mechanical kinetic energy are stored formsof energy. It is easy to see why we regardmechanical potential energy as being stored, butit is not so easy to see the same thing aboutmechanical kinetic energy. Part of the troublecomes about because mechanical kinetic energyis often referred to as the energy of motion, thusleading to the false conclusion that energy intransition is somehow involved. This is not thecase, however. Work is the only form ofmechanical energy that can be properly consideredas energy in transition.

If you have trouble with the idea thatmechanical kinetic energy is stored, rather thanin transition, think of it like this: A bullet thathas been fired from a gun has mechanical kineticenergy because it is in motion. The faster the bulletis moving, the more kinetic energy it has. Thereis no doubt in anybody’s mind that the bullet hasthe capacity to produce an effect, so we may safelysay that it has energy. Although the bullet is notin transition, the energy of the bullet is nottransferred to any other object or system until thebullet strikes some object that resists its passage.When the bullet strikes against a resisting object,then, and only then, can we say that energy intransition exists, in the form of heat and work.

In this example, we are ignoring the fact thatsome work is done against the resistance of theair and that some heat results from the passageof the bullet through the air. But this does notchange the basic idea that kinetic energy is storedenergy rather than energy in transition. The airmust be regarded as a resisting object, whichcauses some of the stored kinetic energy of thebullet to be converted into energy in transition(heat and work) while the bullet is passing throughthe air. However, the major part of the storedkinetic energy does not become energy intransition until the bullet strikes an object firmerthan air which resists its passage.

Mechanical potential energy is measured infoot-pounds. Consider, for example, the rock atthe top of the cliff. If the rock weighs 5 poundsand if the distance from the rock to the earth atthe base of the cliff is 100 feet, 500 foot-poundsof mechanical potential energy exist because ofthe relative positions of the rock and the earth.Another way of expressing this idea is by theformula

where

PE =

W =

D =

PE = W x D,

total potential energy of the object (infoot-pounds),

total weight of the object (in pounds),and

distance between the earth and theobject (in feet).

Mechanical kinetic energy is also measured infoot-pounds. The amount of kinetic energypresent at any one time is directly related to thevelocity of the moving object and to the weightof the moving object.

Mechanical potential energy can be changedinto mechanical kinetic energy. If you push that5-pound rock over the edge of the 100-foot cliff,it begins to fall, and as it falls, it loses potentialenergy and gains kinetic energy. At any givenmoment, the total amount of mechanical energy(potential plus kinetic) stored in the system is thesame—that is, 500 foot-pounds. But the pro-portions of potential energy and kinetic energyare changing all the time as the rock is falling.Just before the rock hits the earth, all the storedmechanical energy is kinetic energy. As the rockhits the earth, the kinetic energy is changed intoenergy in transition—that is, work and heat.

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Mechanical kinetic energy can likewise bechanged into mechanical potential energy. Forexample, suppose you throw a baseball straightup in the air. The ball has kinetic energy whileit is in motion, but the amount of kinetic energydecreases and the amount of potential energyincreases as the ball travels upward. When the ballhas reached its uppermost position, just beforeit starts its fall back to earth, it has onlypotential energy. Then, as it falls back toward theearth, the potential energy is changed into kineticenergy again.

Mechanical energy in transition is calledWORK. When an object is moved through a dis-tance against a resisting force, we say that workhas been done. The formula for calculating workis

W = F × D,

W = work,

F = force, and

D = distance.

where

As you can see from this formula, you needto know how much force is exerted and thedistance through which the force acts before youcan find how much work is done. The unit offorce is the pound. When work is done againstgravity, the force required to move an object isequal to the weight of the object. Why? Becauseweight is a measure of the force of gravity or, inother words, a measure of the force of attractionbetween an object and the earth. How much workwill you do if you lift that 5-pound rock from thebottom of the l00-foot cliff to the top? You willdo 500 foot-pounds of work-the weight of theobject (5 pounds) times the distance (100 feet) thatyou move it against gravity.

We also do work against forces other than theforce of gravity. When you push an object acrossthe deck, you are doing work against friction. Inthis case, the force you work against is not onlythe weight of the object, but also the forcerequired to overcome friction and slide theobject over the surface of the deck.

Notice that mechanical potential energy,mechanical kinetic energy, and work are allmeasured in the same unit, foot-pounds. Onefoot-pound of work is done when a force of 1pound acts through a distance of 1 foot. One foot-pound of mechanical potential energy or mechan-ical kinetic energy is the amount of energy thatis required to accomplish 1 foot-pound of work.

The amount of work done has nothing at allto do with how long it takes to do it. When youlift a weight of 1 pound through a distance of1 foot, you have done one foot-pound of work,regardless of whether you do it in half a secondor half an hour. The rate at which work is doneis called POWER. The common unit of measure-ment for power is the HORSEPOWER (hp). Bydefinition, 1 horsepower is equal to 33,000 foot-pounds of work per minute or 550 foot-poundsof work per second. Thus a machine that iscapable of doing 550 foot-pounds of work persecond is said to be a 1 horsepower machine. (Asyou can see, your horsepower rating would notbe very impressive if you did 1 foot-pound ofwork in half an hour. Figure it out. It works outto be just a little more than one-millionth of ahorsepower.)

Thermal Energy

All substances are composed of very smallparticles called molecules. The energy associatedwith molecules is called thermal energy. Thermalenergy, like mechanical energy, exists in twostored forms and in one transitional form. Thetwo stored forms of thermal energy are called(1) internal potential energy, and (2) internalkinetic energy. Thermal energy in transition iscalled HEAT.

Although molecules are too small to be seen,they behave in some ways pretty much like thelarger objects we considered in the discussion ofmechanical energy. Molecules have energy ofposition (internal potential energy) because of theforces which attract molecules to each other. Inthis way, they are somewhat like the rock and theearth we considered before. Molecules haveenergy of motion (internal kinetic energy) becausethey are constantly in motion. Thus, the twostored forms of thermal energy—internal poten-tial energy and internal kinetic energy—are insome ways similar to mechanical potential energyand mechanical kinetic energy, except thateverything is on a smaller scale.

For most purposes, we will not need todistinguish between the two stored forms ofthermal energy. Therefore, instead of referringto internal potential energy and internal kineticenergy, from now on we will simply use the terminternal energy. By internal energy, then, we willmean the sum total of all internal energy storedin the substance or system because of the motionof the molecules and because of the forces ofattraction between molecules. Although the term

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may be unfamiliar to you, you probably knowmore about internal energy than you realize.Because molecules are constantly in motion, theyexert a pressure on the walls of the pipe, cylinder,or other object in which they are contained. Also,the temperature of any substance arises from, andis directly proportional to, the activity ofthe molecules. Therefore, every time you readthermometers and pressure gauges you are findingout something about the amount of internalenergy contained in the substance. High pressuresand temperatures indicate that the molecules aremoving rapidly and that the substance thereforehas a lot of internal energy.

HEAT is a more familiar term than internalenergy, but may actually be more difficult todefine correctly. The important thing to rememberis that heat is THERMAL ENERGY INTRANSITION—that is, it is thermal energy thatis moving from one substance or system toanother.

An example will help to show the differencebetween heat and internal energy. Suppose thereare two equal lengths of pipe made of identicalmaterials and containing steam at the samepressure and temperature. One pipe is wellinsulated; the other is not insulated at all. Fromeveryday experience you know that more heat willflow from the uninsulated pipe than from theinsulated pipe. When the two pipes are first filledwith steam, the steam in one pipe contains exactlyas much internal energy as the steam in the otherpipe. We know this is true because the two pipescontain equal volumes of steam at the samepressure and at the same temperature. After a fewminutes, the steam in the uninsulated pipe willcontain much less internal energy than the steamin the insulated pipe, as we can tell by measuringthe pressure and the temperature of the steam ineach pipe. What has happened? Stored thermalenergy-internal energy-has moved from onesystem to another, first from the steam to thepipe, then from the uninsulated pipe to the air.This MOVEMENT or FLOW of thermal energyfrom one system to another is called heat.

A good deal of confusion exists concerning theuse of the word heat. For example, you will hearpeople say that a hot object contains a lotof heat when they really mean that it contains alot of internal energy. Or you will hear that heatis added to, or removed from a substance.Since heat is the FLOW of thermal energy, it canno more be added to a substance than the flowof water could be added to a river. (You mightadd water, and this addition might increase the

flow; but you could hardly say that you addedflow.) The only kind of thermal energy that canin any sense be added to or removed from asubstance is INTERNAL ENERGY.

The distinction between heat and internalenergy must be clear in your own mind before youcan understand the basic principles of a gasturbine plant.

Energy Transformations

The machinery and equipment in the engineer-ing plant aboard ship are designed either to carryenergy from one place to another or to changea substance from one form to another. Theprinciples of energy transformations and some ofthe important energy changes that occur in theshipboard propulsion cycle are discussed in thefollowing paragraphs.

CONSERVATION OF ENERGY.—Thebasic principle dealing with the transformation ofenergy is the PRINCIPLE OF THE CON-SERVATION OF ENERGY. This principle canbe stated in several ways. Most commonly,perhaps, it is stated that energy can be neitherdestroyed nor created, but only transformed.Another way to state this principle is that the totalquantity of energy in the universe is always thesame. Still another way of expressing this principleis the equation, Energy in = Energy out.

The energy out may be quite different in formfrom the energy in, but the total amount of energyinput must always equal the total amount ofenergy output.

Another principle, the PRINCIPLE OF THECONSERVATION OF MATTER, states thatmatter can be neither created nor destroyed,but onlv transformed. As vou probablv knowthe development of the atom bomb demonstratedthat matter can be converted into energy; otherdevelopments have demonstrated that energy canbe converted into matter. Therefore, the principleof the conservation of energy and the principleof the conservation of matter are no longerconsidered as two parts of a single law or principlebut are combined into one principle. That prin-ciple states that matter and energy are inter-changeable, and the total amount of energy andmatter in the universe is constant.

The interchangeability of matter and energyis mentioned here only to point out that the state-ment energy in must equal energy out is notstrictly true for certain situations. However, anynoticeable conversion of matter into energy or

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energy into matter can occur only under veryspecial conditions, which we need not considernow. All the energy transformations that we willdeal with can be understood quite simply if weconsider only the principle of the conservation ofenergy-that is, ENERGY IN MUST EQUALENERGY OUT.

TRANSFORMING HEAT TO WORK.—The energy transformation of primary interestin the shipboard gas turbine plant is thetransformation from heat to work. To see howthis transformation occurs, we need to considerthe pressure, temperature, and volume relation-ships which hold true for gases. These relation-ships may be summarized as follows:

When the temperature is held constant,increasing the pressure on a gas causes a pro-portional decrease in volume. Decreasing thepressure causes a proportional increase involume.

When the pressure is held constant,increasing the temperature of a gas causes a pro-portional increase in volume. Decreasing thetemperature causes a proportional decrease involume.

When the volume is held constant,increasing the temperature of a gas causes aproportional increase in pressure. Decreasing thetemperature causes a proportional decrease inpressure.

LEVERS/LEVERAGE

The LEVER is one of the six types of simplemachines. The others are the BLOCK, theWHEEL AND AXLE, the INCLINED PLANE,the SCREW, and the GEAR. Physicists recognizeonly two basic “principles” in machines; namely,the lever and the inclined plane. The block, thewheel and axle, and the gear may be consideredlevers. The wedge and the screw use the principleof the inclined plane. In this section we will discusslevers and leverage only.

The simplest machine, and perhaps the onewith which you are most familiar, is the LEVER.A seesaw is a familiar example of a lever in whichone weight balances the other. There are threebasic parts which you will find in all levers;namely, the FULCRUM, a force or EFFORT,and a RESISTANCE. The mechanical advantagegained by using a lever is called LEVERAGE.

Look at the lever in figure 4-12. You see thepivotal point F (fulcrum); the effort (E), whichyou apply at a distance (A) from the fulcrum; anda resistance (R), which acts at a distance (a) fromthe fulcrum. Distances A and a are the lever arms.Figure 4-13 shows the three classes of levers. Thelocation of the fulcrum (the fixed or pivot point)with relation to the resistance (or weight) and theeffort determines the lever class.

FIRST-CLASS LEVERS

In the first-class lever (fig. 4-13, view A), thefulcrum is located between the effort and theresistance. As mentioned earlier, the seesaw is agood example of the first-class lever. The amountof weight and the distance from the fulcrum canbe varied to suit the need. Another good exampleis the oars in a rowboat. Notice that the sailor in

Figure 4-12.—A simple lever.

Figure 4-13.—Three classes of levers.

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figure 4-14 applies his effort on the handles ofthe oars. The oarlock acts as the fulcrum, and thewater acts as the resistance to be overcome. Inthis case, as in figure 4-12, the force is appliedon one side of the fulcrum and the resistance tobe overcome is applied to the opposite side, hencethis is a first-class lever. Crowbars, shears, andpliers are common examples of this class of lever.

SECOND-CLASS LEVERS

The second-class lever (fig. 4-13, view B) hasthe fulcrum at one end; the effort is applied atthe other end. The resistance is somewherebetween these points. The wheelbarrow infigure 4-15 is a good example of a second-classlever. If you apply 50 pounds of effort to thehandles of a wheelbarrow 4 feet from the fulcrum(wheel), you can lift 200 pounds of weight 1 footfrom the fulcrum. If the load were placed further

Figure 4-14.—Oars are levers.

Figure 4-15.—This makes it easier.

back away from the wheel, would it be easier orharder to lift?

Both first- and second-class levers arecommonly used to help in overcoming bigresistances with a relatively small effort.

THIRD-CLASS LEVERS

Occasionally you will want to speed up themovement of the resistance even though you haveto use a large amount of effort. Levers that helpyou accomplish this are third-class levers. Asshown in figure 4-13, view C, the fulcrum is atone end of the lever and the weight or resistanceto be overcome is at the other end, with theeffort applied at some point between. You canalways spot third-class levers because you will findthe effort applied between the fulcrum and theresistance. Look at figure 4-16. It is easy to seethat while point E is moving the short distance(e), the resistance (R) has been moved a greaterdistance (r). The speed of R must have beengreater than that of E since R covered a greaterdistance in the same length of time.

Your arm (fig. 4-17) is a third-class lever. Itis this lever action that makes it possible for youto flex your arms so quickly. Your elbow is thefulcrum. Your biceps muscle, which ties into yourforearm about an inch below the elbow, appliesthe effort; and your hand is the resistance, locatedsome 18 inches from the fulcrum. In the splitsecond it takes your biceps muscle to contract aninch, your hand has moved through an 18-incharc. You know from experience that it takes a bigpull at E to overcome a relatively small resistanceat R. Just to remind yourself of this principle, tryclosing a door by pushing on it about 3 or 4 inchesfrom the hinges (fulcrum). The moral is, youdon’t use third-class levers to do heavy jobs, youuse them to gain speed.

Figure 4-16.—A third-class lever.

4-16

Figure 4-17.—Your arm is a lever.

MEASUREMENT OFTEMPERATURE

Temperature is measured by bringing ameasuring system (such as a thermometer) intocontact with the system to be measured. You willoften need to know the expansion of a liquid, thepressure of a gas, emf, electrical resistance, orsome other mechanical, electrical, or opticalproperty that has a definite and known relation-ship to temperature.

The measurement of a property other thantemperature can take us only so far in themeasuring of temperature. In noting changes intemperature, we must be able to assign anumerical value to any given temperature. For thiswe need temperature scales. The two most familiartemperature scales are the Celsius scale and theFahrenheit scale.

The Celsius scale is often called the centigradescale in the United States and Great Britain. Byinternational agreement, however, the name waschanged from centigrade to Celsius in honor ofthe eighteenth-century Swedish astronomer,Anders Celsius. The symbol for a degree on thisscale (no matter whether it is called Celsius orcentigrade) is °C. The Celsius scale takes 0°C asthe freezing point and 100°C as the boiling pointof pure water at standard sea level atmosphericpressure. The Fahrenheit scale takes 32°F as thefreezing point and 212°F as the boiling point ofpure water at standard sea level atmosphericpressure. The interval between the freezing point

and the boiling point is divided into 100 degreeson the Celsius scale and divided into 180 degreeson the Fahrenheit scale.

Since the actual value of the interval betweenthe freezing point and the boiling point isidentical, the numerical readings on Celsius andFahrenheit thermometers have no absolutesignificance and the size of the degree is arbitrarilychosen for each scale. The relationship betweendegrees Celsius and degrees Fahrenheit is givenby the formulas

and

Many people have trouble remembering theseformulas, with the result that they either get themmixed up or have to look them up in a book everytime a conversion is necessary. If you concentrateon trying to remember the basic relationshipsgiven by these formulas, you may find it easierto make conversions. The essential points toremember are these:

1. Celsius degrees are larger than Fahrenheitdegrees. One Celsius degree is equal to 1.8Fahrenheit degrees, and each Fahrenheit degreeis only 5/9 of a Celsius degree.

2. The zero point on the Celsius scalerepresents exactly the same temperature as the32-degree point on the Fahrenheit scale.

3. The temperatures 100°C and 212°F areidentical.

In some scientific and engineering work,particularly where heat calculations are involved,an absolute temperature scale is used. The zeropoint on an absolute temperature scale is the pointcalled ABSOLUTE ZERO. Absolute zero isdetermined theoretically, rather than by actualmeasurement. Since the pressure of a gas atconstant volume is directly proportional to thetemperature, we assume that the pressure of a gasis a valid measure of its temperature. On thisassumption, the lowest possible temperature(absolute zero) is defined as the temperature atwhich the pressure of a gas would be zero.

Two absolute temperature scales have been inuse for many years. The Rankine absolute scaleis an extension of the Fahrenheit scale; it issometimes called the Fahrenheit absolute scale.

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Degrees on the Rankine scale are the same sizeas degrees on the Fahrenheit scale, but the zeropoint on the Rankine scale is at — 459.67°Fahrenheit. In other words, absolute zero is zeroon the Rankine scale and — 459.67° on theFahrenheit scale.

A second absolute scale, the Kelvin, is morewidely used than the Rankine. The Kelvin scalewas originally conceived as an extension of theCelsius scale, with degrees of the same size butwith the zero point shifted to absolute zero.Absolute zero on the Celsius scale is — 273.15°.

In 1954, a new international absolute scale wasdeveloped. The new scale was based upon onefixed point, rather than two. The one fixed pointwas the triple point of water —that is, the pointat which all three phases of water (solid, liquid,and vapor) can exist together in equilibrium. The

triple point of water, which is 0.01°C above thefreezing point of water, was chosen because it canbe reproduced with much greater accuracy thaneither the freezing point or the boiling point. Onthis new scale, the triple point was given the value273.16 K. Note that neither the word degrees northe symbol ° is used; instead, the units arereferred to as Kelvin and the symbol K is usedrather than the symbol °K.

In 1960 the triple point of water was finallyadopted as the fundamental reference for thistemperature scale. The scale now in use is theinternational Practical Temperature Scale of 1968(IPTS-68). However, you often see this scalereferred to as the Kelvin scale.

Although the triple point of water isconsidered the basic or fundamental reference forthe IPTS-68, five other fixed points are used to

Figure 4-18.—Comparison of Kelvin, Celsius, Fahrenheit, and Rankine temperatures.

4-18

help define the scale. These are the freezing pointof gold, the freezing point of silver, the boilingpoint of sulfur, the boiling point of water, andthe boiling point of oxygen.

Figure 4-18 is a comparison of the Kelvin,Celsius, Fahrenheit, and Rankine temperatures.All of the temperature points listed above absolutezero are considered as fixed points on the Kelvinscale except for the freezing point of water. Theother scales are based on the freezing and boilingpoints of water.

PRESSURE DEFINITIONS

Pressure like temperature is one of the basicengineering measurements and one that must befrequently monitored aboard ship. As withtemperature readings, pressure readings provideyou with an indication of the operating conditionof equipment. Pressure is defined as the force perunit area.

The simplest pressure units are the ones thatindicate how much force is applied to an area ofa certain size. These units include pounds persquare inch, pounds per square foot, ounces persquare inch, newtons per square millimeter, anddynes per square centimeter, depending upon thesystem you use.

You also use another kind of pressure unit thatinvolves length. These units include inches ofwater, inches of mercury (Hg), and inches of someother liquid of a known density. Actually, theseunits do not involve length as a fundamentaldimension. Rather, length is taken as a measureof force or weight. For example, a reading of Iinch of water (1 in. H20 means that the exertedpressure is able to support a column of water 1inch high, or that a column of water in a U-tubewould be displaced 1 inch by the pressure beingmeasured. Similarly, a reading of 12 inches ofmercury (12 in.Hg) means that the measuredpressure is sufficient to support a column ofmercury 12 inches high. What is really beingexpressed (even though it is not mentioned in thepressure unit) is that a certain quantity of material(water, mercury, and so on) of known densityexerts a certain definite force upon a specifiedarea. Pressure is still force per unit area, even ifthe pressure unit refers to inches of some liquid.

In interpreting pressure measurements, a greatdeal of confusion arises because the zero pointon most pressure gauges represents atmosphericpressure rather than zero absolute pressure.Thus it is often necessary to specify the kind

of pressure being measured under any givenconditions. To clarify the numerous meanings ofthe word pressure, the relationships among gauge,atmospheric, vacuum, and absolute pressures, areshown in figure 4-19.

GAUGE PRESSURE is the pressure actuallyshown on the dial of a gauge that registerspressure relative to atmospheric pressure. Anordinary pressure gauge reading of zero does notmean that there is no pressure in the absolutesense; rather, it means that there is no pressurein excess of atmospheric pressure.

ATMOSPHERIC PRESSURE is the pressureexerted by the weight of the atmosphere. At sealevel, the average pressure of the atmosphere issufficient to hold a column of mercury at theheight of 76 centimeters or 29.92 inches. Since acolumn of mercury 1 inch high exerts a pressureof 0.49 pound per square inch at its base, acolumn of mercury 29.92 inches high exerts apressure that is equal to 29.92 × 0.49 or about 14.7psi. Since we are dealing now in absolute pressure,we say that the average atmospheric pressure atsea level is 14.7 pounds per square inch absolute(psia). It is zero on the ordinary pressure gauge.

Notice, however, that the figure of 14.7 psiarepresents the average atmospheric pressure at sealevel; it does not always represent the actualpressure being exerted by the atmosphere at themoment that a gauge is being read.

Figure 4-19.—Relationships among gauge pressure, atmos-pheric pressure, vacuum, and absolute pressure.

4-19

BAROMETRIC PRESSURE is the term usedto describe the actual atmospheric pressure thatexists at any given moment. Barometric pressuremay be measured by a simple mercury column orby a specially designed instrument called ananeroid barometer.

A space in which the pressure is less thanatmospheric pressure is said to be under partialvacuum. The amount of vacuum is expressed interms of the difference between the absolutepressure in the space and the pressure ofthe atmosphere. Most commonly, vacuum isexpressed in inches of mercury, with the vacuumgauge scale marked from 0 to 30 in.Hg. Whena vacuum gauge reads zero, the pressure in thespace is the same as atmospheric pressure—or, inother words, there is no vacuum. A vacuum gaugereading of 29.92 in.Hg would indicate a perfect(or nearly perfect) vacuum. In actual practice, itis impossible to obtain a perfect vacuum evenunder laboratory conditions. A reading between0 and 29.92 in.Hg is a partial vacuum.

ABSOLUTE PRESSURE is atmosphericpressure plus gauge pressure or minus vacuum.For example, a gauge pressure of 300 psig equalsan absolute pressure of 314.7 psia (300 + 14.7).Or, for example, consider a space in which themeasured vacuum is 10 in.Hg; the absolutepressure in this space is figured by subtracting themeasured vacuum (10 in.Hg) from the nearlyperfect vacuum (29.92 in.Hg). The absolutepressure then will be 19.92 or approximately 20in.Hg absolute. It is important to note that theamount of pressure in a space under vacuum canonly be expressed in terms of absolute pressure.

You may have noticed that sometimes we usethe letters psig to indicate gauge pressure andother times we merely use psi. By commonconvention, gauge pressure is always assumed

when pressure is given in pounds per square inch,pounds per square foot, or similar units. The g(for gauge) is added only when there is somepossibility of confusion. Absolute pressure, on theother hand, is always expressed as pounds persquare inch absolute (psia), pounds per squarefoot absolute (psfa), and so forth. It is alwaysnecessary to establish clearly just what kind ofpressure we are talking about, unless this is veryclear from the nature of the discussion.

To this point, we have considered only themost basic and most common units of measure-ment. It is important to remember that hundredsof other units can be derived from these units;remember also that specialized fields requirespecialized units of measurement. Additional unitsof measurement are introduced in appropriateplaces throughout the remainder of this trainingmanual. When you have more complicated unitsof measurement, you may find it helpful to firstreview the basic information given here.

SUMMARY

We have discussed the basic laws andprinciples covering electrical and mechanicaltheory. This chapter was provided to give you onlya basis on which to expand your knowledge ofelectrical and mechanical fundamentals. It isimportant that you have a sound understandingof these laws and principles. The complexelectrical systems and the internal pressure-temperature relationships in a simple GTE makeit imperative that you understand the materialpresented. If you have problems understandingthis material, you should reread the pertinentportions until you have absorbed the basicconcepts.

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CHAPTER 5

INDICATING INSTRUMENTS

Constantly used throughout this text is theword monitor. As used in this text, monitor meansto observe, record, or detect an operation orcondition using instruments. As a GSE3/GSM3,your most important job aboard ship is tomonitor. As a watch stander, you observe anddetect malfunctions in the operating equipmentand take the necessary action to prevent damageto the equipment. For accuracy, the best methodof observing and detecting a malfunction in equip-ment is through use of indicating instruments,such as temperature and pressure gauges. Thesegauges range from direct acting, such as ordinarythermometers, to electrically activated resistancedetectors. The main function of all indicatinginstruments is to give information on theoperating condition of the equipment. When youare operating equipment, these instruments giveyou the ability to compare normal operatingconditions or preset limits to the actual operatingconditions. This comparison permits you to detectan abnormal condition before it causes majordamage to the equipment. An example of this isa main reduction gear (MRG) bearing failure. Asa watch stander, by taking your hourly readingsfrom the bearing thermometer, you would noticea rise in temperature from hour to hour; youwould be able to inform your supervisor of asuspected problem. If a sudden failure occurs,such as loss of lube oil to the bearing, the suddenrise in temperature would activate a remote alarmwhen it reached a preset point. The alarm wouldalert personnel in the engine room and the EOOWstation. This would allow the watch to institutecasualty control procedures to minimize thedamage. We used this example to emphasize toyou the importance of indicating instruments toshipboard operation.

In this chapter we describe the various typesof indicating instruments that you, as aGSE3/GSM3, will come in contact with whileoperating and maintaining gas turbine propulsionsystems. These include temperature, pressure,level, and remote indicators. Upon completion of

this chapter, you should be able to describe thetypes of temperature and pressure measuringinstruments, liquid level indicators, electricalindicating instruments, and miscellaneous sensorsused in the control and monitoring of GTEs andauxiliary and support equipment.

TEMPERATURE MEASURINGINSTRUMENTS

Temperature is the degree of hotness orcoldness of a substance measured on a definitescale. Temperature is measured when a measuringsystem, such as a thermometer, is brought intocontact with the system to be measured. You oftenneed to know the expansion of a liquid, thepressure of a gas, emf, electrical resistance, orsome other mechanical, electrical, or opticalproperty that has a definite and known relation-ship to temperature. Thus we infer the tempera-ture of the measured system by the measurementof some property of the system. The temperaturemeasuring instruments that we discuss are of threetypes: mechanical, electrical, and mechanical-electrical. The mechanical-electrical temperatureinstruments are switches.

MECHANICAL TEMPERATUREMEASURING DEVICES

Since temperature is one of the basicengineering variables, temperature measurementis essential to the proper operation of a shipboardengineering plant. You will frequently be calledupon to measure the temperature of steam, water,fuel, lubricating oil, and other vital fluids; inmany cases you will have to enter the results ofthis measurement in engineering records and logs.

Devices used for measuring temperature maybe classified in various ways. In this section wewill discuss only the expansion thermometer types.Expansion thermometers operate on the principlethat the expansion of solids, liquids, and gases

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has a known relationship to temperature changes.The types of expansion thermometers discussedhere are (1) liquid-in-glass thermometers, (2) bi-metallic expansion thermometers, and (3) filled-system thermometers.

Liquid-in-Glass Thermometers

Liquid-in-glass thermometers are probably theoldest, the simplest, and the most widely useddevices for measuring temperature. A liquid-in-glass thermometer (fig. 5-1) has a bulb and a veryfine bore capillary tube containing alcohol, orsome other liquid that expands uniformly as thetemperature rises or contracts uniformly as thetemperature falls. The selection of liquid is basedon the temperature range in which the ther-mometer is to be used.

Almost all liquid-in-glass thermometers aresealed so atmospheric pressure does not affect the

reading. The space above the liquid in this typeof thermometer may be a vacuum or filled withan inert gas such as nitrogen, argon, or carbondioxide.

The capillary bore may be either round orelliptical. In any case, it is very small, so arelatively small expansion or contraction of theliquid causes a relatively large change in theposition of the liquid in the capillary tube.Although the capillary bore itself is very small indiameter, the walls of the capillary tube are quitethick. Most liquid-in-glass thermometers have anexpansion chamber at the top of the bore toprovide a margin of safety for the instrument ifit should accidentally be overheated.

Liquid-in-glass thermometers may havegraduations etched directly on the glass stem orplaced on a separate strip of material locatedbehind the stem. Many thermometers used in ship-board engineering plants have the graduationsmarked on a separate strip; this type is generallyeasier to read than the type that has thegraduations marked directly on the stem.

You will seldom find liquid-in-glass ther-mometers on gas turbine ships. As a GSE/GSM,you may still find this type of thermometer in usein the oil and water test lab for analytical testson fuel, oil, and water.

Bimetallic Expansion Thermometer

Bimetallic expansion thermometers make useof different metals having different coefficientsof linear expansion. The essential element in a

Figure 5-1.—Liquid-in-glass thermometer.Figure 5-2.—Effect of unequal expansion of a bimetallic

strip.

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bimetallic expansion thermometer is a bimetallicstrip consisting of two layers of different metalsfused together. When such a strip is subjected totemperature changes, one layer expands orcontracts more than the other, thus tending tochange the curvature of the strip.

Figure 5-2 shows the basic principle of abimetallic expansion thermometer. When one endof a straight bimetallic strip is fixed in place, theother end tends to curve away from the side thathas the greater coefficient of linear expansionwhen the strip is heated.

For use in thermometers, the bimetallic stripis normally wound into a flat spiral (fig. 5-3), asingle helix, or a multiple helix. The end of thestrip that is not fixed in position is fastened tothe end of a pointer that moves over a circularscale. Bimetallic thermometers are easily adaptedfor use as recording thermometers; a pen isattached to the pointer and positioned in such away that it marks on a revolving chart.

Filled-System Thermometers

In general, filled-system thermometers aredesigned for use in locations where the indicatingpart of the instrument must be placed somedistance away from the point where thetemperature is to be measured. For this reasonthey are often called distant-reading ther-mometers. However, this is not true of all filled-system thermometers. In a few designs, thecapillary tubing is extremely short, and in a few,it is nonexistent. In general, however, filled-systemthermometers are designed to be distant-readingthermometers. Some distant-reading ther-mometers may have capillaries as long as 125 feet.

Figure 5-3.—Bimetallic thermometer (flat, spiral strip).

There are two basic types of filled-systemthermometers. One has a Bourdon tube thatresponds primarily to changes in the volume ofthe filling fluid; the other is one in which the Bour-don tube responds primarily to changes in thepressure of the filling fluid. Clearly, some pressureeffect will exist in volumetric thermometers, andsome volumetric effect will exist in pressurethermometers.

A distant-reading thermometer (fig. 5-4)consists of a hollow metal sensing bulb at one endof a small-bore capillary tube, which is connectedat the other end to a Bourdon tube or other devicethat responds to volume changes or to pressurechanges. The system is partially or completelyfilled with a fluid that expands when heated andcontracts when cooled. The fluid may be a gas,an organic liquid, or a combination of liquid andvapor.

The device usually used to indicatetemperature changes by its response to volumechanges or to pressure changes is called aBourdon tube. A Bourdon tube is a curved ortwisted tube which is open at one end and sealed

Figure 5-4.—Distant-reading, Bourdon-tube thermometer.

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at the other (fig. 5-5). The open end of the tubeis fixed in position, and the sealed end is free tomove. The tube is more or less elliptical in crosssection; it does not form a true circle. Itbecomes less circular when there is an increasein the volume or in the internal pressure of thecontained fluid; this tends to straighten the tube.Opposing this action, the spring action of the tubemetal tends to coil the tube. Since the open endof the Bourdon tube is rigidly fastened, the sealedend moves as the volume or pressure of thecontained fluid changes. A pointer is attached tothe sealed end of the tube through appropriatelinkages; the assembly is placed over anappropriately calibrated dial. The result is aBourdon-tube gauge that may be used formeasuring temperature or pressure, dependingupon the design of the gauge and the calibrationof the scale.

Bourdon tubes are made in several shapes forvarious applications. The C-shaped Bourdon tubeshown in figure 5-5 is perhaps the most commonlyused type; spiral and helical Bourdon tubes areused where design requirements include the needfor a longer length Bourdon tube.

ELECTRICAL TEMPERATUREMEASURING DEVICES

On the gas turbine propulsion plant, you willhave to monitor temperature readings at remotelocations. Expansion thermometers provideindications at the machinery locations or on gauge

Figure 5-5.—C-shaped Bourdon tube.

panels in the immediate area. To provide remoteindications at a central location, you use electricaltemperature measuring devices in conjunctionwith signal conditioners. The devices we willdiscuss in this section are the resistancetemperature detectors (RTDs), the resistancetemperature elements (RTEs), and thermocouples.These devices sense variable temperatures at agiven point in the system and transmit the signalsto a remotely located indicator.

Resistance Temperature Detectors

The RTDs operate on the principle thatelectrical resistance changes in a predictablemanner with temperature changes. The elementsof RTDs are made of nickel, copper, or platinum.Nickel and copper are used for temperatures of600°F or lower. Platinum elements are used fortemperatures of 600°F or greater. Figure 5-6shows two typical types of RTDs.

As with the bimetallic thermometers, you willusually find RTDs mounted in thermowells.Thermowells protect sensors from physicaldamage by keeping them isolated from themedium being measured. This arrangement alsolets you change the RTD without securing thesystem in which it is mounted. This makes yourmaintenance easier and less messy.

As temperature increases around an RTD, thecorresponding resistance will also increase at aproportional value. The temperature applied toan RTD, if known, will give you a knownresistance value. You can find these resistancevalues listed in tables in the manufacturers’technical manuals. Normally, only a fewresistance values are given.

To test an RTD, you will have to heat it toa specific temperature. At this temperature theresistance of the RTD should be at the resistanceshown in the table. The most common methodof heating an RTD is to use a pan of hot waterand a calibrated thermometer. Some newer shipsand repair activities test RTDs using a thermobulbtester. This method is more accurate and easierto use. For specific instructions, refer to themanufacturers’ technical manuals supplied withthe equipment.

The most common fault you will find with anRTD will be either a short circuit or an opencircuit. You can quickly diagnose these faults byusing digital display readings or data log print-outs. By observing the reading or the printout,you may find that the indication is either zero ora very low value. A malfunction of this type

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Figure 5-6.—Two typical types of RTDs.

means a short circuit exists in either the RTD orits associated wiring. A very high reading, suchas 300°F on a 0°F to 300°F RTD, could indicatean open circuit. You should compare thesereadings to local thermometers. This ensures thatno abnormal conditions exist within the equip-ment that the RTD serves.

If an RTD is faulty, you should replace it atthe earliest opportunity. Internal repairs cannotbe made to RTDs at the shipboard level. Untilyou can replace the faulty RTD, you shouldinform the watch standers that the RTD isunreliable. The engine-room watch standersshould periodically take local readings to ensurethe equipment is operating normally.

sensor increases, the resistance of the RTE alsoincreases at a proportional value. All RTEs thatyou encounter have a platinum element and havean electrical resistance of 100 ohms at atemperature of 32°F. Four different temperatureranges of RTEs are commonly used, but you willfind that the probe size varies. The fourtemperature ranges and their probe sizes are asfollows:

Resistance Temperature Elements

The most common types of temperaturesensors you will find in gas turbine propulsionplants are the RTEs. They operate on the same You may find some RTEs that are connectedprinciple as the RTDs. As the temperature of the to remote mounted signal conditioning modules.

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These modules convert the ohmic value ofthe RTE to an output range of 4 to 20milliamperes (mA) direct current (dc). How-ever, most RTEs read their value directlyinto the propulsion electronics as an ohmicvalue.

The 0° to + 400°F and the — 60° to +500°Frange RTEs are commonly mounted in athermowell. Since you can change the RTEwithout securing the equipment it serves, this alsosimplifies maintenance.

Thermocouples

Thermocouple sensors are used to monitorLM2500 power turbine inlet temperature (T5.4)and Allison 501-K17 turbine inlet temperature(TIT). Although each engine uses a different typeof thermocouple, the theory of operation is thesame. These sensors work on the principle thatwhen two dissimilar metals are fused together ata junction by heat, a small voltage is produced.The amount of this voltage is directly proportionalto the T5.4 or TIT.

Figure 5-7 shows the LM2500 and the Allison501-K17 thermocouples. You should note thatalthough they are physically different, theiroperation is the same. Both thermocouples

are composed of the metals Chromel andAlumel.

LM2500 THERMOCOUPLES.—TheLM2500 uses eleven thermocouples to monitorT5.4. Individual thermocouples cannot be re-placed though, as they are arranged in fourgroups. These groups, or harnesses, are thecomponents you must change if you have a faultythermocouple. Figure 5-8 shows the fourharnesses. You should note that the two upperharnesses and the lower right harness eachcontains three thermocouples. The lower leftharness has only two thermocouples. Be verycareful when you replace a harness. Take care notto damage a probe or bend the harness. Forcomplete detailed information on replacement ofthermocouple harnesses, refer to the PropulsionGas Turbine Module LM2500, Volume 2, Part 3,NAVSEA S9234-AD-MMO-050.

ALLISON 501-K17 THERMPCOUPLES.—Eighteen dual-element, Chromel-Alumel thermo-couples are used on the Allison 501-K17 tomonitor TIT. Unlike the thermocouples of theLM2500, you can change these thermocouplesindividually. Each of these sensors has twoindependent elements that allow two samplingcircuits per thermocouple. Only one circuit isused for monitoring TIT; the other circuit is not

Figure 5-7.—Thermocouples.

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Figure 5-8.—LM2500 thermocouple harness.

5-7

monitored. Figure 5-9) shows the thermocoupleinstallation on the Allison 501 - K17.

The interconnecting harness for the thermo-couples, as shown in figure 5-9, mounts on theouter combustion case forward of the ther-mocouples. This harness includes four separateleads for each of the eighteen sensors. Twoseparate electrical circuits arc maintained. Theharness is made in two halves, a right-hand sideand a left-hand side. Note in figure 5-9 that theharness is split near the thermocouple junction.This allows you to easily remove the wiringwithout major engine disassembly. The electricalsignals from the thermocouples are averagedwithin the harness. The output of the thermo-couple harness is sent to the local operating panel(LOCOP) for signal conditioning.

A faulty thermocouple will give you a falseTIT reading. The TIT is a basic parameter for theliquid fuel valve (LFV) adjustment. Therefore, afaulty sensor would result in an incorrectlyadjusted LFV. You should check the continuity.of the thermocouples if you suspect the TITreading is incorrect. Also, check it if you suspectthe LFV is out of adjustment. The thermocouplecontinuity is read with an ohmmeter. Each ther-mocouple has four terminals, but only two areused for monitoring TIT. Find the two terminalsthat are used for TIT and read the resistancebetween them. If the reading on a thermocoupleis over 10 ohms, you must replace that sensor.

For instructions on thermocouple replacement,refer to the appropriate manufacturers’ technicalmanuals.

TEMPERATURE SWITCHES

Temperature switches operate from tempera-ture changes occurring in an enclosure, or in theair surrounding the temperature sensing element.The operation of the temperature switch is notmuch different than that of the pressure switch.Actually, both switches are operated by changesin pressure. The temperature element is arrangedso changes in temperature cause a change in theinternal pressure of a sealed-gas or air-filled bulbor helix, which is connected to the actuating deviceby a small tube or pipe. Figure 5-10 shows youa temperature switch and two types of sensingelements.

Construction

You can connect the bulb and helix units tothe switch section. The bulb unit (fig. 5-10,item A) is normally used when you need to controlliquid temperatures. However, it may control airor gas temperatures. This only happens if thecirculation around it is rapid and the temperaturechanges at a slow rate.

The helical unit (fig. 5-10, item B) has beenspecifically designed for air and gas temperature

Figure 5-9.—Allison 501-K17 thermocouple harness.

5-8

Figure 5-10.—Temperature switch with two types ofsensing elements. A . Bulb unit. B. Helix unit.

control circuits. For the thermal unit to be mosteffective, it must be located at a point ofunrestricted circulation. This is so it can “feel”the average temperature of the substance you wishto control.

Temperature changes cause a change in thevolume of the sealed-in gas, which causes move-ment of a diaphragm. The movement istransmitted by a plunger to the switch arm. Themoving contact is on the arm. A fixed contact maybe arranged so the switch will open or close ona temperature rise. This allows the switch contactsto be arranged to close when the temperaturedrops to a predetermined value and to open whenthe temperature rises to the desired value. Thereverse action can be obtained by a change in thecontact positions.

The difference in temperature for the contactopening set point and closing set point is thedifferential. The switch mechanism has a built-indifferential adjustment so the differential canbe varied over a small range. Once set, thedifferential remains essentially constant at alltemperature settings.

Some switches are stamped WIDE DIF-FERENTIAL. These switches are adjusted in thesame manner described for the regular controls.However, because of slight design changes, it is

possible to get wider variation in differentialsettings.

Adjustments

To set the operating range of the switch, turnthe differential adjustment screw (fig. 5-11)counterclockwise against the stop for minimumdifferential. Bring the temperature to the valueat which the circuit is to be closed. If the switchcontacts are open at this temperature, turn therange screw slowly clockwise until the contactsclose. If the contacts are closed when the desiredtemperature is reached, turn the range screwcounterclockwise until the contacts open; thenturn the screw slowly clockwise until the contactsclose. These adjustments set the closingtemperature.

The temperature is now raised to the pointwhere the circuit is to be opened. Since thedifferential adjustment is now set at minimum,the circuit will probably open at a lowertemperature than desired; therefore, turn thedifferential adjustment screw clockwise to widenthe differential until the desired openingtemperature is obtained. For further instructionson how to adjust these switches, refer to themanufacturers’ technical manuals.

PRESSURE MEASURINGINSTRUMENTS

Pressure, like temperature, is one of the basicengineering measurements and one that must be

Figure 5-11.—Temperature switch.

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frequently monitored aboard ship. As with temper-ature readings, pressure readings provide you withan indication of the operating condition of equip-ment. Pressure measuring instruments that wediscuss are of three types: mechanical, electrical,and mechanical-electrical. The mechanical-electrical pressure instruments are switches.

MECHANICAL PRESSUREMEASURING INSTRUMENTS

Two of the primary mechanical pressuremeasuring instruments found aboard ship are the

Bourdon-tube and the bellows elements. Bourdon-tube elements are suitable for the measurementof very high pressures up to 100,000 psig. Theupper limit for bellows elements is about 800 psig.

Bourdon-Tube Elements

Bourdon-tube elements used in pressuregauges are essentially the same as those de-scribed for use in filled-system thermometers.Bourdon tubes for pressure gauges are madeof brass, phosphor bronze, stainless steel,

Figure 5-12.—Simplex Bourdon-tube pressure gauge.

Figure 5-13.—Duplex Bourdon-tube pressure gauge.

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beryllium-copper, or other metals, dependingupon the requirements of service.

Bourdon-tube pressure gauges are oftenclassified as simplex or duplex, depending uponwhether they measure one pressure or two. Asimplex gauge has only one Bourdon tube andmeasures only one pressure. Figure 5-12 shows asimplex Bourdon-tube pressure gauge with viewsof the dial and gear and operating mechanisms.The pointer marked RED HAND in view A is amanually positioned hand that is set at orslightly above the maximum normal operating pressureof the machinery. The hand marked POINTERis the only hand that moves in responseto pressure changes.

When two Bourdon tubes are mounted in asingle case, with each mechanism acting in-dependently but with the two pointers mounted

on a common dial, the assembly is called a duplexgauge. Figure 5-13 shows a duplex gauge withviews of the dial and operating mechanism. Notethat each Bourdon tube has its own pressureconnection and its own pointer. Duplex gaugesare used to give simultaneous indication of thepressure at two different locations.

Bourdon-tube vacuum gauges are marked offin inches of mercury, as shown in figure 5-14.When a gauge is designed to measure bothvacuum and pressure, it is called a compoundgauge; it is marked off both in inches of mercuryand in psig, as shown in figure 5-15.

Differential pressure may also be measuredwith Bourdon-tube gauges. One kind of Bourdon-tube differential pressure gauge is shown infigure 5-16. This gauge has two Bourdon tubes

Figure 5-14.—Bourdon-tube vacuum gauge.

Figure 5-15.—Compound Bourdon-tube gauge. Figure 5-16.—Bourdon-tube differential pressure gauge.

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but only one pointer. The Bourdon tubes areconnected in such a way that they are the pressuredifference, rather than either of the two actualpressures indicated by the pointer.

Bellows Element

A bellows elastic element is a convoluted unitthat expands and contracts axially with changesin pressure. The pressure to be measured can beapplied to the outside or to the inside of thebellows; in practice, most bellows measuringdevices have the pressure applied to the outsideof the bellows, as shown in figure 5-17. LikeBourdon-tube elements, bellows elastic elementsare made of brass, phosphor bronze, stainless

steel, beryllium-copper, or other metal suitablefor the intended service of the gauge.

Most bellows gauges are spring-loaded--thatis, a spring opposes the bellows and thus preventsfull expansion of the bellows. Limiting theexpansion of the bellows in this way protects thebellows and prolongs its life. In a spring-loadedbellows element, the deflection is the result of theforce acting on the bellows and the opposing forceof the spring.

Although some bellows instruments can bedesigned for measuring pressures up to 800 psig,their primary application aboard ship is in themeasurement of quite low pressures or smallpressure differentials.

Figure 5-17.—Bellows gauge.

5-12

Many differential pressure gauges are of thebellows type. In some designs, one pressure isapplied to the inside of the bellows and the otherpressure is applied to the outside. In other designs,a differential pressure reading is obtained byopposing two bellows in a single case.

Bellows elements are used in various applica-tions where the pressure-sensitive device must bepowerful enough to operate not only the in-dicating pointer but also some type of recordingdevice.

ELECTRICAL PRESSURE MEASURINGINSTRUMENTS (TRANSDUCERS)

Transducers are devices that receive energyfrom one system and retransmit it to anothersystem. The energy retransmitted is often in adifferent form than that received. In this section,we will discuss the pressure transducer. This devicereceives energy in the form of pressure andretransmits energy in the form of electricalcurrent.

Transducers allow monitoring at remotelocations on gas turbine propulsion plants.Mechanical gauges provide pressure readings atthe machinery locations or on gauge panels in theimmediate area. At a central location remotereadings are provided by using transducers in

conjunction with signal conditioners. Transducersprovide the capability of sensing variable pressuresand transmitting them in proportional electricalsignals. Pressure transducers, like pressureswitches, are widely used in ship propulsion andauxiliary machinery spaces. They are used tomonitor alarms and in machinery operation.

Pressure Transducer Operation

Pressure transducers are generally designed tosense absolute, gauge, or differential pressure.The typical unit (fig. 5-18) receives pressurethrough the pressure ports. It transmits anelectrical signal, proportional to the pressureinput, through the electrical connector. Pressuretransducers are available in pressure ranges from0 to 6 inches water differential to 0 to 10,000 psig.Regardless of the pressure range of a specific unit,the electrical output is always the same. Theelectrical signal is conditioned by the signalconditioners before being displayed on an analogmeter or a digital readout located on one of thecontrol consoles.

Pressure Transducer Calibration

Pressure transducers should be calibrated ona bench before installation. The equipment needed

Figure 5-18.—Pressure transducer assembly.

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and its setup are shown in figures 5-19 and 5-20. you will have to send your transducers to aAfter setting up your test equipment as shown, calibration activity. If you have a problem withyou will be ready to start calibrating the a transducer or have to replace a transducer, youtransducer. If your ship doesn’t have a calibra- can compare it to a known standard by using thetion lab or isn’t qualified to calibrate gauges, then calibration kit.

Figure 5-19.—Calibration setup for absolute pressure transducers.

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Figure 5-20.—Calibration setup for pressure transducers.

5-15

The following simple setup proceduralsteps should help you understand and calibratepressure transducers commonly found on gasturbine ships. These steps are condensed fromparagraphs 8.2-24 and 8.2-25 of the PropulsionGas Turbine Module LM2500, Volume 2, Part 3,NAVSEA S9234-AD-MMO-050.

To calibrate a 0- to 250-psig transducer, closethe instrumentation valve and remove the cap.Remove the cover from the transducer andconnect the multimeter. The multimeter shouldread 4 mA ± 0.3. If necessary, adjust the ZEROADJUST potentiometer. Now connect thepressure hose to the instrumentation valve andapply 250 psig to the transducer. The multimetershould read 20 mA ± 0.3. If necessary, adjust theSPAN ADJUST potentiometer to obtain thisreading. Recheck first and last values wheneveryou make either ZERO or SPAN adjustments.Now check the middle value, in this case 125 psi,and the multimeter should read 12 mA ± 0.3. Toderive the middle value of the output current,subtract 4 from 20, divide by 2, and add 4 tothe sum. For information on calibration oftransducers, refer to the Propulsion GasTurbine Module LM2500, Volume 2, Part 3,NAVSEA S9234-AD-MMO-050, or PressureTransducer - Strain Gauge Assembly, NAV-SEA 0987-LP-059-5010.

NOTE: When calibrating a differentialpressure transducer, apply the pressure tothe high port and vent the low port to theatmosphere.

PRESSURE SWITCHES

Another type of pressure indicating instrumentis the contact or pressure switch. This instrumenteither opens or closes a set of contacts at a presetpressure. This switch can provide you with analarm indication or initiate an action such asstopping a piece of equipment at a preset pressure.

Often when a measured pressure reaches acertain maximum or minimum value, a pressuresensing device activates. This may be in the formof an alarm to sound a warning or a light to givea signal. The pressure switch shown in figure 5-21is a device commonly used to energize orde-energize an auxiliary control system. Thisswitch is normally contained in a metal case witha removable cover. It is equipped with a pressureport and an electrical connector. The pressureswitch converts, through a set of contacts, themotion of a diaphragm or bellows into an

Figure 5-21.—Pressure switch.

electrical signal. Pressure switches are usedto sense gauge or differential pressures onpneumatic as well as hydraulic systems. They aremanufactured in many sizes and configurations,but all perform basically the same function.

Construction of Pressure Switches

One of the simplest pressure switches is thesingle-pole, single-throw, quick-acting one, alsoshown in figure 5-21. This switch contains aseamless metallic bellows in the housing, whichis displaced by changes in pressure. The bellowsworks against an adjustable spring that determinesthe pressure needed to actuate the switch.Through suitable linkages, the spring causes thecontacts to open or close the electrical circuit. Thisis done automatically when the operating pressurefalls or rises from a specified value. A permanentmagnet in the switch mechanism provides apositive snap on both the opening and theclosing of the contacts. This snap action preventsexcessive arcing of the contacts. The switch isconstantly energized. However, it is the closingof the contacts that energizes the entire electricalcircuit.

You can find switches in many sizes andconfigurations. The switch used depends upon itsapplication.

5-16

Setting Pressure Switches

To set a pressure switch, you first have to seta known pressure in the operational range of theswitch. Normally, you do this by using a test setuplike that shown in figure 5-22. In an emergency,you can use the pressure of the system in whichthe switch is installed. But you should reset theswitch as soon as possible using a calibrator.Many types of pressure calibrators are used in thefleet. Refer to the manufacturer’s technicalmanual for the correct operating instructions foryour unit.

The adjustments on the pressure switches arethe same as the adjustments on the temperatureswitches that we described earlier in this chapter.

LIQUID LEVEL INDICATORS

In a gas turbine propulsion plant, you willhave to monitor systems and tanks for liquid level.Sometimes you are only required to know if a levelexceeds or goes below a certain preset parameter.Other circumstances require that you know theexact level. If only a predetermined limit isneeded, you can use a float switch. This will makecontact when the set point is reached and willsound an alarm. If you need to know a specificlevel, then you must use a variable sensing device.

The sensor used for indicating a tank level iscommonly called a tank level indicator (TLI). Thissensor will tell you the exact amount of liquid ina tank. In the following paragraphs we willdescribe the operation of each of these sensors andtheir applications. Refer to the manufacturers’technical manuals for more information on theprocedures used to adjust each type of device.

TANK LEVEL INDICATORS

Many tank levels on gas turbine ships aremonitored to provide the exact liquid level inthem. Fuel tanks, for example, are monitored toensure they do not overflow. They are alsomonitored to let the engineer officer know theamount of fuel aboard the ship. The sensorsused to monitor these levels are TLIs. Each of thelevel-monitored tanks contains a level transmitter.A typical transmitter section contains a voltagedivider resistor network extending the length ofthe section. Magnetic reed switches are tapped atl-inch intervals along the resistor network. Thereed switches are sequentially connected throughseries resistors to a common conductor. This net-work is enclosed in a stem that is mounted ver-tically in the tank. A float containing bar magnetsrides up and down the stem as the level changes.

In many tanks, you have to use more than onetransmitter section to measure the full range. The

Figure 5-22.—Typical setup fur calibrating a pressure device.

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physical arrangement of some tanks makes thisnecessary. When multiple sections are used, theyare electrically connected as one continuousdivider network.

Two types of floats are used. In noncompen-sated tanks, the float is designed to float at thesurface of the fuel or JP-5. For seawatercompensated tanks, the float is designed to stayat the seawater/fuel interface.

CONTACT LEVEL SENSORS

Many times you do not have to know the exactlevel of a tank until it reaches a preset level. Whenthis type of indication is needed, you can use acontact or float switch. Two types of float levelswitches are used on gas turbine ships. One type

is the lever operated switch. It is activated by ahorizontal lever attached to a float. The float islocated inside the tank. When the liquid levelreaches a preset point, the lever activates theswitch.

The other type of level switch uses a magnet-equipped float sliding on a vertical stem. The stemcontains a hermetically sealed, reed switch. Thefloat moves up and down the stem with the liquidlevel. It magnetically opens or closes the reedswitch as the float passes over it. Figure 5-23shows the construction of the magneticallyoperated float switch. Magnetic float switchesmay be constructed with more than one float ona stem. This type of switch can detect multiplelevels in the same tank, such as a high- and low-level alarm. You may also wire multiple stemstogether to provide this same feature.

Figure 5-23.—Magnetic float switch.

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ELECTRICAL INDICATINGINSTRUMENTS

Electrical indicating instruments (meters) areused to display information that is measured bysome type of electrical sensor. Meters on thecontrol console, although they display units suchas pressure or temperature, are in fact dcvoltmeters. The signal being sensed is conditionedby a signal conditioner. It is then converted to0- to 10-volt dc, proportional to the parametersbeing sensed. Electrical values, such as wattageand current, are measured and displayed at ship’sservice switchboards. The electrical values are thenconditioned and displayed on the electric plantconsole. The meters on the electrical plantconsole are also the 0- to 10-volt dc type of meters.The meters we will discuss in this chapter arefound on the ship’s service switchboards.Normally, shipboard repair is not done on switch-board meters. If you suspect the switchboardmeters are out of calibration or broken,you should have them sent to a repair facility.You can find more information on the theoryof operation of these meters in the NavyElectricity and Electronics Training Series(NEETS), Module 3, Introduction to CircuitProtection, Control, and Measurement, NAV-EDTRA 172-03-00-79.

VOLTMETERS

Both dc and ac voltmeters determine voltagethe same way. They both measure the current thatthe voltage is able to force through a highresistance. Voltage measuring is always connectedin parallel with (across) a circuit. The

Figure 5-24.—An ac voltmeter.

voltmeters installed in switchboards and controlconsoles (fig. 5-24) all have a fixed resistancevalue. Portable voltmeters, used as test equip-ment, usually have a variable resistance. Theseresistances are calibrated to the different rangesthat the meters will display. The normal range forthe switchboard and electric plant meters is 0 to600 volts.

AMMETERS

Ammeters (fig. 5-25) are used to indicate thecurrent passing through a conductor. Differenttypes of ammeters are used for either ac or dc.However, any ac ammeter will indicate on dc witha lower degree of accuracy.

The construction of installed ammeters is suchthat they are not able to handle the current thatpasses through the conductor being measured.Ammeters are required to be connected in serieswith the circuit to be measured. Since the meterscannot handle the high switchboard current, theswitchboard ammeters operate through currenttransformers. This arrangement isolates theinstruments from line potential. The currenttransformer produces in its secondary a definitefraction of the primary current. This arrangementmakes it possible to measure large amounts ofcurrent with a small ammeter.

CAUTION

THE SECONDARY OF A CURRENTTRANSFORMER CONTAINS A DAN-GEROUS VOLTAGE. NEVER WORKAROUND OR ON CURRENT TRANS-FORMERS WITHOUT TAKINGPROPER SAFETY PRECAUTIONS.

Figure 5-25.—An ac ammeter.

5-19

FREQUENCY METERS

Frequency meters (fig. 5-26) measure the cyclesper second rate of ac. The range of frequencymeters found on gas turbine ships is between 55hertz (Hz) and 65 hertz. Frequency of the acused on ships rarely varies below 57 Hz andseldom exceeds 62 Hz. A frequency meter mayhave a transducer that converts the inputfrequency to an equivalent dc output. Thetransducer is a static device employing twoseparately tuned series resonant circuits that feeda full-wave bridge rectifier. A change in frequencycauses a change in the balance of the bridge. Thiscauses a change in the dc output voltage.

KILOWATT METERS

Wattage is measured by computing values ofcurrent, voltage, and power factor. The kilowattmeters used on ships automatically take thesevalues into account when measuring kilowatt(kW) produced by a generator. Kilowatt meters

Figure 5-26.—Frequency meter.

Figure 5-27.—Kilowatt meter.

are connected to both current and potentialtransformers to allow them to measure linecurrent and voltage. The kW meter shown infigure 5-27 is similar to the ones used on gasturbine ships. Since each type of generator on gasturbine ships is rated differently, the scale will bedifferent on each class of ship.

The amount of power produced by a generatoris measured in kilowatts. Therefore, whenbalancing the electrical load on two or moregenerators, you should ensure kW is matched.Loss of the kW load is the first indication of afailing generator. For example, two generators arein parallel and one of the two units experiencesa failure. To determine which of the two units isfailing, compare the kW reading. Normally, thegenerator with the lowest kW would be thefailing unit. However, you should know there isone case where this is not true. During anoverspeed condition, both units will increase infrequency. But the failing unit will be the one withthe higher kW load.

SYNCHROSCOPES

Before connecting a 3-phase generator tobus bars already connected to one or moreother generators, you must ensure that certainconditions prevail. A synchroscope is the deviceyou will use to find out if the followingconditions have been met:

1. Phase sequence must be the same forgenerator and bus bars.

2. Generator and bus-bar voltage must be thesame.

3. Generator and bus-bar frequency must bethe same.

4. Generator frequency must be practicallyconstant for an appreciable period of time.

5. The generator and bus-bar voltage must bein phase. They must reach their maximumvoltages at the same time. This is so that whenconnected, they will oppose excessive circulationof current between the two machines.

Figure 5-28 shows a synchroscope. It isbasically a power factor meter connected tomeasure the phase relation between the generatorand bus-bar voltages. The moving element is freeto rotate continuously. When the two frequenciesare exactly the same, the moving element holdsa fixed position. This shows the constant phaserelation between the generator and bus-barvoltages. When the frequency is slightly different,the phase relation is always changing. In this case,the moving element of the synchroscope rotates

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Figure 5-28.—Synchroscope.

constantly. The speed of rotation is equal to thedifference in frequency; the direction showswhether the generator is fast or slow. Thegenerator is placed on line when the pointer slowlyapproaches a mark. This mark shows that thegenerator and bus-bar voltages are in phase.

PHASE-SEQUENCE INDICATORS

The sequence in which the currents of a3-phase system reach their maximum valuesis determined by phase-sequence indicators.Figure 5-29 shows an example of this type ofindicator.

Gas turbine ships have phase-sequenceindicators installed in switchboards which may beconnected to shore power. These instrumentsindicate whether shore power is of correct orincorrect phase sequence before shipboard equip-ment is connected to shore power. Three-phasemotors, when connected to incorrect phase-sequence power, rotate in the opposite direction.

The phase-sequence indicator has three neonlamps that light when all three phases areenergized. A meter connected to a network ofresistors and condensers shows correct or in-correct sequence on a marked scale.

MISCELLANEOUS SENSORS

Several of the sensors used in the gas turbinepropulsion plant are not pressure or temperaturesensors. These devices, such as ice detectors,speed sensors, vibration sensors, and UV flamedetectors, are used to monitor or protect the gasturbine plant from damage.

ICE DETECTOR SYSTEM

Under certain atmospheric conditions, ice canform in the inlet airflow system. This can happen

Figure 5-29.—Phase-sequence indicator.

when the temperature falls below 41°F and therelative humidity is above 70 percent. Theformation of ice in the inlet has two detrimentaleffects. It can restrict airflow to the gas turbinewith a resultant loss of power. Also, if allowedto build up in large quantities, ice chunks canbreak off. They can go through the gas turbinecompressor causing foreign object damage (FOD).

The ice detector sensor is located in the lowerleft corner of the inlet barrier wall. It sensesinlet temperature and humidity and transmitsproportional electrical signals to the signalconditioner. The signal conditioner is mountedon the underside of the base. It provides a signalfor the icing alarm at the propulsion console whenicing conditions exist.

Ice Detectors

The detector shown in figure 5-30 consists ofa sensor assembly mounted in a body secured to

Figure 5-30.—Ice detector.

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a mounting plate assembly. The body andmounting plate are machined from stainless steel.A filter cover assembly protects the sensingelement while allowing the passage of atmosphericair over two sensors. It consists of a temperaturesensor and a humidity sensor. Electrical con-nection to the sensing element is made througha fixed plug secured to the mounting plate.

Changes in temperature of the air flowing overthe sensor assembly vary the electrical resistanceof the temperature sensor. As temperaturedecreases, the resistance of the temperatureincreases; at 41°F, resistance is about 2.4 kilohms(kΩ). The change in resistance modifies a dc signalin the ice-detector signal conditioner.

Changes in the moisture content of the airflowing over the sensor assembly vary theelectrical resistance of the humidity sensor. Thehumidity sensor is a salt-treated wafer. As itabsorbs moisture from the surrounding air, itsresistance decreases as the humidity increases; at70 percent relative humidity, resistance is about435 kΩ . The change in resistance affects the feed-back to an amplifier in the ice-detector signalconditioner.

Ice-Detector Signal Conditioners

The ice-detector signal conditioner (fig. 5-3 1)is contained in a metal box. The box is attachedto the underside of the base/enclosure. Itcontains two printed-circuit board assemblies, atransformer, and a relay and capacitor. The boxis closed by a cover bearing identification labels.

Figure 5-31.—Ice-detector signal conditioner.

The two screws on the top cover access holes totwo potentiometers positioned on the uppercircuit board assembly.

SPEED SENSORS

One of the more important parameters sensedin a gas turbine propulsion plant is speed. Speedis measured on reduction gears and gas turbines.The reduction gear speed is monitored to informthe propulsion plant operators of the propellershaft speed. Gas turbine speed is measured toensure the turbine does not overspeed. Also, gasturbine speed is used as an input to the controlsystems of the engine. Two types of speedsensors are used to measure the required speeds.One type is the tachometer generator, used onreduction gears. The other type is the magneticspeed pickup, used to sense gas turbine speeds.In some applications, it is used to sense reductiongear speeds.

Tachometer Generators

Main reduction gears (MRGs) use tachometergenerators to provide electrical signals for remoteindication of propulsion shaft speed. The outputof the tachometer generator is voltage pulsesproportional to the speed of the propeller shaft.The tachometer signal is amplified. Then it is sentto the propulsion electronics for use in data andbell logging and display of shaft speed. You canfind more information on tachometer generatoroperation by referring to the related technicalmanual found on your ship.

Magnetic Speed Pickup Transducer

The magnetic speed pickup transducer isusually referred to as a magnetic speed pickup andis the most common type of speed sensor foundin gas turbine propulsion plants. It is used forsensing gas turbine speed on the LM2500 and theAllison 501-K17. It is also used to measurereduction gear speed for controllable pitchpropeller (CPP) systems on the FFG-7 class ships.The MRGs of the DD-963 class ships use magneticspeed pickups for sensing clutch engagementspeeds.

Magnetic speed pickups sense speed by usinga toothed gear that cuts the magnetic field of thepickup. The output of the sensor is a square-waveac voltage. This voltage is converted to aproportional dc voltage in a signal conditioner.The output of the signal conditioner is used in

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control functions as well as for indications ofequipment speed. Figure 5-32 shows the magneticspeed pickup transducer used in an LM2500power turbine.

The most important thing you shouldremember when replacing a speed pickup is tocheck the depth setting. You can measure thedepth clearance with either a special tool suppliedby the equipment manufacturer or a depthmicrometer. Set the proper clearance by usingeither shims or locknuts. If you do not set theclearance properly, the magnetic sensor will beeither too close to the toothed gear or too far fromit. If it is too close, it may be damaged by therotating gear. If it is too far from the gear, theunit will fail to give the proper voltage signal.Always refer to the appropriate manufacturer’stechnical manual when you replace a magneticspeed sensor.

VIBRATION SENSORS

One of the first indications of internal damageto gas turbines is high vibration. High-vibrationconditions can be indications of failed bearings,damaged blading, or a dirty compressor. The GTEs foundon Navy ships use velocity vibration and accelerometer-type pickups. Figure 5-33 shows a typical velocityvibration pickup used on GTEs.

Figure 5-33.—Velocity vibration transducer.

The vibration pickup is a linear velocitytransducer (transfers mechanical energy toelectrical energy). The magnetic circuit is closedthrough the circular air gap between the pole piecesleeve in the case and the pole pieces on themagnet assembly. The air gap is interrupted bythe coils. (The flux field in the air gap isnormally aligned with the approximate midpointof the two coils by the centering action of the twosprings.) As the engine vibrates, the rigidly

Figure 5-32.—Magnetic speed pickup used on the LM2500 power turbine.

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mounted case and coil move with the vibration. from sources external to the gas turbine. By theDue to its inertia, the magnet assembly remains use of these filters, you can narrow the cause ofstationary. The coil windings cut through the vibration down to one section of an engine. Onmagnetic field in the air gap, inducing a voltage the LM2500 the power turbine operates at a slowerin the coils. This voltage is proportional to the speed than the gas generator. By use of filters,velocity of vibration. You may use vibration filters you can determine the location of the engineto filter out the frequencies that are transmitted vibration. You can tell if it is from the

Figure 5-34.—Flame-detector block diagram and typical flame detector.

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lower-frequency power turbine or the higher-frequency gas generator.

ULTRAVIOLET FLAME DETECTOR

Ultraviolet flame detectors are used in GTMsto detect the presence of fire. These sensors areused along with temperature sensors in theLM2500. They are used alone in the Allison501-K17 for fire protection. The fire detectionsystem alerts the operator of fire in the module.On twin-shaft ships it also activates the fire stopsequence and releases fire-extinguishing agents toextinguish a fire in the Allison 501-K17 moduleor in the LM2500 module.

Flame Detector

The flame detector (fig. 5-34) is an electronictube that responds to UV radiation in ordinaryflames. It is insensitive to infrared (IR) andordinary visible light sources. The tube has twosymmetrical electrodes within the gas-filledenvelope. It operates on pulsating dc. Alternating

current enters the detector and is stepped upby a transformer. This ac is then rectified topulsating dc, which is fed to the UV sensor.Ultraviolet light containing wavelengths in therange of 1900 to 2100 angstrom units ionize thegas in the tube. This allows the current to flowthrough the tube. The current then goes to a pulsetransformer which couples it to the signalconditioner.

Flame-Detector Signal Conditioner

The flame-detector signal conditioner (fig.5-35) is contained in a metal box. The box isattached to the underside of the base/enclosureof the LM2500. On the Allison 501-K17, the unitis located in the alarm terminal box on thegenerator end of the module base.

Identical detector cards (one for each UVsensor) are located in the signal conditioner. Thedetector card amplifies, rectifies, and filters thecurrent pulses from the UV sensor. This providesan output voltage level proportional to the UVlight level at the UV sensor.

Figure 5-35.—Flame-detector signal conditioner block diagram and typical signal conditioner unit.

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SUMMARY

In this chapter we introduced you tomany of the sensing and indicating devicesfound on gas turbine ships. Only the mostcommon and frequently used devices were

covered. You may come across other typesof specialized sensors or indicating instrumentsnot covered in this chapter. If you have anyquestions on indicating instruments, alwaysrefer to the appropriate manufacturer’s technicalmanual.

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CHAPTER 6

PIPING SYSTEM COMPONENTS

As a GSE3 or GSM3, some portion of yourdaily routine will involve working with valves,steam traps, filters and strainers, heat exchangers,piping, gasket and packing materials, fasteners,and insulation. You will be responsible for routinemaintenance of this equipment in your spaces andpossibly throughout the ship. The machinery ofa system cannot work properly unless the pipingsystem components that make up that system arein good working order. The information in thischapter, as it is throughout the book, is of a broadand general nature. You should refer to theappropriate manufacturer’s technical manualsand/or ship’s plans, information books, and plantor valve manuals for specific problems withindividual equipment.

After studying this chapter, you should havethe knowledge to be able to (1) identify,maintain, and repair the various types ofmanually, mechanically, remotely, electrically,and pneumatically operated valves common to thegas turbine propelled class ships; the various typesof steam traps common in the waste heat systems;the various types of strainers and filters used inthe ships’ fuel oil, lube oil, hydraulic oil, and airsystems; the various types of heat exchangers usedin ships’ auxiliary systems; the various types ofpiping, tubing, and hose assemblies; and thevarious fittings, unions, joints, supports, hangers,and safety shields used with the above com-ponents; (2) identify, select, and properly usegaskets, packing material, and O-rings used forrepair and maintenance; (3) identify, inspect, andselect the correct fasteners used for securing thecomponents of various piping systems or valves;and (4) select and install the correct insulationmaterials used in today’s modern naval shipsystems.

VALVES

A valve is any device used for the control offluids in a closed system. In this section we will

discuss valve construction and the most commontypes of valves you will use in the day-to-dayoperation and maintenance of the various ship-board engineering systems. Valves are typed orclassified according to their use in a system.

VALVE CONSTRUCTION

Valves are usually made of bronze, brass, castor malleable iron, or steel. Steel valves are eithercast or forged and are made of either plain steelor alloy steel. Alloy steel valves are used in high-pressure, high-temperature systems; the disks andseats (internal sealing surfaces) of these valves areusually surfaced with a chromium-cobalt alloyknown as Stellite. Stellite is extremely hard.

Brass and bronze valves are never used insystems where temperatures exceed 550°F. Steelvalves are used for all services above 550°F andin lower temperature systems where internal orexternal conditions of high pressure, vibration,or shock would be too severe for valves made ofbrass or bronze. Bronze valves are used almostexclusively in systems that carry salt water. Theseats and disks of these valves are usually madeof Monel, a metal that has excellent corrosion-and erosion-resistant qualities.

Most submarine seawater valves are made ofan alloy of 70 percent copper to 30 percent nickel(70/30).

VALVE TYPES

Although many different types of valves areused to control the flow of fluids, the basic valvetypes can be divided into two general groups: stopvalves and check valves.

Besides the basic types of valves, many specialvalves, which cannot really be classified as eitherstop valves or check valves, are found in theengineering spaces. Many of these valves serve tocontrol the pressure of fluids and are known aspressure-control valves. Other valves are identifiedby names that indicate their general function, such

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as thermostatic recirculating valves. The follow-ing sections deal first with the basic types of stopvalves and check valves, then with some of themore complicated special valves.

Stop Valves

Stop valves are used to shut off or, in somecases, partially shut off the flow of fluid. Stopvalves are controlled by the movement of the valvestem. Stop valves can be divided into four generalcategories: globe, gate, butterfly, and ball valves.Plug valves and needle valves may also beconsidered stop valves. Since plug valves andneedle valves are covered sufficiently in Fireman,NAVEDTRA 10520, we will not discuss them inthis manual.

GLOBE VALVES.—Globe valves are prob-ably the most common valves in existence. Theglobe valve derives its name from the globularshape of the valve body. However, positiveidentification of a globe valve must be madeinternally because other valve types may haveglobular appearing bodies. Globe valve inlet andoutlet openings are arranged in several ways tosuit varying requirements of flow. Figure 6-lshows the common types of globe valve bodies;straight-flow, angle-flow, and cross-flow. Globevalves arc used extensively throughout theengineering plant and other parts of the ship ina variety of systems.

GATE VALVES.—Gate valves are used whena straight-line flow of fluid and minimum

Figure 6-1.—Types of globe valve bodies.

restriction is desired. Gate valves are so namedbecause the part which either stops or allows flowthrough the valve acts somewhat like the openingor closing of a gate and is called, appropriately,the gate. The gate is usually wedge shaped. Whenthe valve is wide open, the gate is fully drawn upinto the valve, leaving an opening for flowthrough the valve the same size as the pipe inwhich the valve is installed. Therefore, there islittle pressure drop or flow restriction through thevalve. Gate valves are not suitable for throttlingpurposes since the control of flow would bedifficult due to valve design and since the flowof fluid slapping against a partially open gate cancause extensive damage to the valve. Except asspecifically authorized, gate valves should not beused for throttling.

Gate valves are classified as either RISING-STEM or NONRISING-STEM valves. On thenonrising-stem gate valve shown in figure 6-2, thestem is threaded on the lower end into the gate.As the handwheel on the stem is rotated, the gatetravels up or down the stem on the threads, whilethe stem remains vertically stationary. This typeof valve almost always has a pointer-type indicatorthreaded onto the upper end of the stem toindicate valve position.

Figure 6-2.—Cutaway view of a gate valve (nonrising-stemtype).

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The rising-stem gate valve, shown in figure6-3, has the stem attached to the gate; the gateand stem rise and lower together as the valve isoperated.

Gate valves used in steam systems have flexiblegates. The reason for using a flexible gate is toprevent binding of the gate within the valve whenthe valve is in the closed position. When steamlines are heated, they will expand, causing somedistortion of valve bodies. If a solid gate fitssnugly between the seat of a valve in a coldsteam system, when the system is heated andpipes elongate, the seats will compress againstthe gate, wedging the gate between them andclamping the valve shut. This problem is over-come by use of a flexible gate (two circularplates attached to each other with a flexible hubin the middle). This design allows the gate to flexas the valve seat compresses it, thereby preventingclamping.

BUTTERFLY VALVES.—The butterflyvalve, one type of which is shown in figure 6-4,may be used in a variety of systems aboard ship.These valves can be used effectively in freshwater,saltwater, JP-5, F-76 (naval distillate), lube oil,and chill water systems aboard ship. The butterfly

Figure 6-3.—Cutaway view of a gate valve (rising-stemtype).

Figure 6-4.—Butterfly valve.

valve is light in weight, relatively small, relativelyquick-acting, provides positive shut-off, and canbe used for throttling.

The butterfly valve has a body, a resilient seat,a butterfly disk, a stem, packing, a notchedpositioning plate, and a handle. The resilient seatis under compression when it is mounted in thevalve body, thus making a seal around theperiphery of the disk and both upper and lowerpoints where the stem passes through the seat.Packing is provided to form a positive seal aroundthe stem for added protection in case the sealformed by the seat should become damaged.

To close or open a butterfly valve, turn thehandle only one quarter turn to rotate the disk90°. Some larger butterfly valves may have ahandwheel that operates through a gearingarrangement to operate the valve. This methodis used especially where space limitation preventsuse of a long handle.

Butterfly valves are relatively easy to maintain.The resilient seat is held in place by mechanicalmeans, and neither bonding nor cementing isnecessary. Because the seat is replaceable, thevalve seat does not require lapping, grinding, ormachine work.

BALL VALVES.—Ball valves, as the nameimplies, are stop valves that use a ball to stop or

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start the flow of fluid. The ball (fig. 6-5) performsthe same function as the disk in the globe valve.When the valve handle is operated to open thevalve, the ball rotates to a point where the holethrough the ball is in line with the valve bodyinlet and outlet, When the valve is shut, whichrequires only a 90° rotation of the handwheel formost valves, the ball is rotated so the hole isperpendicular to the flow openings of the valvebody, and flow is stopped.

Most ball valves are of the quick-acting type(requiring only a 90° turn to operate the valveeither completely open or closed), but many areplanetary gear operated. This type of gearingallows the use of a relatively small handwheel andoperating force to operate a fairly large valve. Thegearing does, however, increase the operating timefor the valve. Some ball valves contain a swingcheck located within the ball to give the valve acheck valve feature. Ball valves are normallyfound in the following systems aboard ship:seawater, sanitary, trim and drain, air, hydraulic,and oil transfer.

Check Valves

Check valves are used to allow fluid flow ina system in only one direction. They are operatedby the flow of fluid in the piping. A check valvemay be of the swing type, lift type, or balltype.

Figure 6-5.—Typical seawater ball valve.

As we have seen, most valves can be classifiedas being either stop valves or check valves. Somevalves, however, function either as stop valves oras check valves-depending on the position of thevalve stem. These valves are known as STOP-CHECK VALVES.

A stop-check valve is shown in cross sectionin figure 6-6. This type of valve looks very muchlike a lift-check valve. However, the valve stemis long enough so when it is screwed all the waydown it holds the disk firmly against the seat, thuspreventing any flow of fluid. In this position, thevalve acts as a stop valve. When the stem is raised,the disk can be opened by pressure on the inletside. In this position, the valve acts as a checkvalve, allowing the flow of fluid in only onedirection. The maximum lift of the disk iscontrolled by the position of the valve stem.Therefore, the position of the valve stem limitsthe amount of fluid passing through the valveeven when the valve is operating as a checkvalve.

Stop-check valves are widely used throughoutthe engineering plant. Stop-check valves are

Figure 6-6.—Stop-check valve.

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used in many drain lines and on the discharge sideof many pumps.

Special-Purpose Valves

There are many types of automatic pressurecontrol valves. Some of them merely provide anescape for pressures exceeding the normalpressure; some provide only for the reduction ofpressure; and some provide for the regulation ofpressure.

RELIEF VALVES.—Relief valves areautomatic valves used on system lines and equip-ment to prevent overpressurization. Most reliefvalves simply lift (open) at a preset pressure andreset (shut) when the pressure drops only slightlybelow the lifting pressure. Figure 6-7 shows a reliefvalve of this type. System pressure simply actsunder the valve disk at the inlet of the valve. Whensystem pressure exceeds the force exerted by thevalve spring, the valve disk lifts off its seat, allow-ing some of the system fluid to escape throughthe valve outlet until system pressure is reducedto just below the relief set point of the valve. Thespring then reseats the valve. An operating leveris provided to allow manual cycling of the reliefvalve or to gag it open for certain tests. Virtuallyall relief valves are provided with some type ofdevice to allow manual cycling.

Other types of relief valves are the high-pressure (HP) air safety relief valve and the bleedair surge relief valve. Both of these types of valvesare designed to open completely at a specified lift

Figure 6-7.—Typical relief valve.

pressure and to remain open until a specific resetpressure is reached-at which time they shut.Many different designs of these valves are used,but the same result is achieved.

S P R I N G - L O A D E D R E D U C I N GVALVES.—Spring-loaded reducing valves, onetype of which is shown in figure 6-8, are used ina wide variety of applications. Low-pressure airreducers and others are of this type. The valvesimply uses spring pressure against a diaphragmto open the valve. On the bottom of thediaphragm, the outlet pressure (the pressure in thereduced pressure system) of the valve forces thedisk upward to shut the valve. When the outletpressure drops below the set point of the valve,the spring pressure overcomes the outlet pressureand forces the valve stem downward, openingthe valve. As the outlet pressure increases,approaching the desired value, the pressure underthe diaphragm begins to overcome springpressure, forcing the valve stem upwards,shutting the valve. You can adjust the downstreampressure by removing the valve cap and turningthe adjusting screw, which varies the springpressure against the diaphragm. This particular

Figure 6-8.—Pressure-reducing (spring-loaded) valve.

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spring-loaded valve will fail in the open positionif a diaphragm rupture occurs.

REMOTE-OPERATED VALVES.—Remoteoperating gear is installed to provide a means ofoperating certain valves from distant stations.Remote operating gear may be mechanical,hydraulic, pneumatic, or electric.

Some remote operating gear for valves isused in the normal operation of valves. Forexample, the main drain system manual valves areopened and closed by a reach rod or a series ofreach rods and gears. Reach rods may be used tooperate engine-room valves in instances where thevalves are difficult to reach from the operatingstations.

Other remote operating gear is installed asemergency equipment. Some of the main drain

and almost all of the secondary drain systemvalves are equipped with remote operating gears.You can operate these valves locally, or in anemergency, you can operate them from remotestations. Remote operating gear also includes avalve position indicator to show whether the valveis open or closed.

PRESSURE-REDUCING VALVES.—Pres-sure-reducing valves are automatic valves thatprovide a steady pressure into a system that is ata lower pressure than the supply system. Reducingvalves of one type or another are found, forexample, in firemain, seawater, and other systems.A reducing valve can normally be set for anydesired downstream pressure within the designlimits of the va1ve. Once the valve is set, thereduced pressure will be maintained regardless of

Figure 6-9.—Air-operated control pilot.

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changes in the supply pressure (as long as thesupply pressure is at least as high as the reducedpressure desired) and regardless of the amount ofreduced pressure fluid that is used.

Various designs of pressure-reducing valvesare in use. Two of the types most commonlyfound on gas turbine ships are the spring-loadedreducing valve (already discussed) and the air-pilotoperated diaphragm reducing valve.

Air-pilot operated diaphragm control valvesare used extensively on naval ships. The valvesand pilots are available in several designs to meetdifferent requirements. They may be used toreduce pressure, to increase pressure, as unloadingvalves, or to provide continuous regulation ofpressure. Valves and pilots of very similar designcan also be used for other services, such as liquid-level control and temperature control.

The air-operated control pilot may be eitherdirect acting or reverse acting. A direct-acting, air-operated control pilot is shown in figure 6-9. Inthis type of pilot, the controlled pressure-thatis, the pressure from the discharge side of thediaphragm control valve-acts on top of adiaphragm in the control pilot. This pressure isbalanced by the pressure exerted by the pilotadjusting spring. If the controlled pressureincreases and overcomes the pressure exerted bythe pilot adjusting spring, the pilot valve stem isforced downward. This action causes the pilot

Figure 6-10.—Diaphragm control valve, downward-seatingtype.

valve to open, thereby increasing the amount ofoperating air pressure going from the pilot to thediaphragm control valve. A reverse-acting pilothas a lever that reverses the pilot action. In areverse-acting pilot, therefore, an increase incontrolled pressure produces a decrease inoperating air pressure.

In the diaphragm control valve, operating airfrom the pilot acts on the valve diaphragm. Thesuperstructure, which contains the diaphragm, isdirect acting in some valves and reverse acting inothers. If the superstructure is direct acting, theoperating air pressure from the control pilot isapplied to the TOP of the valve diaphragm. Ifthe superstructure is reverse acting, the operatingair pressure from the pilot is applied to theUNDERSIDE of the valve diaphragm.

Figure 6-10 shows a very simple type of direct-acting diaphragm control valve with operating airpressure from the control pilot applied to the topof the valve diaphragm. Since the valve in thefigure is a downward seating valve, any increasein operating air pressure pushes the valve stemdownward toward the closed position.

Now look at figure 6-11. This is also a direct-acting valve with operating air pressure fromthe control pilot applied to the top of the

Figure 6-11.—Diaphragm control valve, upward-seatingtype.

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valve diaphragm. Note that the valve shown infigure 6-11 is more complicated than the oneshown in figure 6-10 because of the added springsunder the seat. The valve shown in figure 6-11 isan upward seating valve rather than a downwardseating valve. Therefore, any increase in operatingair pressure from the control pilot tends to OPENthis valve rather than to close it.

As you have seen, the air-operated controlpilot may be either direct acting or reverse acting.The superstructure of the diaphragm control valvemay be either direct acting or reverse acting. And,the diaphragm control valve may be either upwardseating or downward seating. These three factors,as well as the purpose of the installation,determine how the diaphragm control valve andits air-operated control pilot are installed inrelation to each other.

To see how these factors are related, let’sconsider an installation in which a diaphragmcontrol valve and its air-operated control pilot areused to supply controlled-steam pressure.

Figure 6-12 shows one arrangement that youmight use. Assume that the service requirementsindicate the need for a direct-acting, upward-seating diaphragm control valve. Can you figureout which kind of a control pilot-direct actingor reverse acting-should be used in thisinstallation?

Try it first with a direct-acting control pilot.As the controlled pressure (discharge pressurefrom the diaphragm control valve) increases,increased pressure is applied to the diaphragm ofthe direct-acting control pilot. The valve stem is

Figure 6-12.—Arrangement of control pilot and diaphragmcontrol valve for supplying reduced-steam pressure.

pushed downward and the valve in the controlpilot is opened. This increases the operating airpressure from the control pilot to the top of thediaphragm control valve. The increased operatingair pressure acting on the diaphragm of the valvepushes the stem downward, and since this is anupward seating valve, this action OPENS thediaphragm control valve still wider. Obviously,this won’t work for this application. AnINCREASE in controlled pressure must resultin a DECREASE in operating air pressure.Therefore, we made a mistake in choosing thedirect-acting control pilot. For this particularpressure-reducing application, you should choosea REVERSE-ACTING control pilot.

It is not likely that you will be required todecide which type of control pilot and diaphragmcontrol valve is needed in any particularinstallation. But you must know how and whythey are selected so you do not make mistakes inrepairing or replacing these units.

PRIORITY VALVES.—In systems with twoor more circuits, it is sometimes necessary to havesome means of supplying all available fluid to oneparticular circuit in case of a pressure drop in thesystem. A priority valve is often incorporated inthe system to ensure a supply of fluid to thecritical/vital circuit. The components of thesystem are arranged so the fluid to operate eachcircuit, except the one critical/vital circuit, must

Figure 6-13.—Priority valve.

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flow through the priority valve. A priority valvemay also be used within a subsystem containingtwo or more actuating units to ensure a supplyof fluid to one of the actuating units. In this case,the priority valve is incorporated in the subsystemin such a location that the fluid to each actuatingunit, except the critical/vital unit, must flowthrough the valve.

Figure 6-13 shows one type of priority valve.View A of figure 6-13 shows the valve in thepriority-flow position; that is, the fluid must flowthrough the valve in the direction shown by thearrows to get to the noncritical/vital circuits oractuating units. With no fluid pressure in thevalve, spring tension forces the piston against thestop and the poppet seats against the hole in thecenter of the piston. As fluid pressure increases,the spring compresses and the piston moves to theright. The poppet follows the piston, seating thehole in the center of the piston until the pre-set pressure is reached. (The preset pressuredepends upon the requirements of the system andis set by the manufacturer.) Assume that the

critical/vital circuit or actuating unit requires1500 psi. When the pressure in the valve reaches1500 psi, the poppet reaches the end of its travel.As the pressure increases, the piston continues tomove to the right, which unseats the poppet andallows flow through the valve, as shown in viewA of figure 6-13. If the pressure drops below 1500psi, the compressed spring forces the piston to theleft, the poppet seats, and flow through the valvestops.

Figure 6-13, view B, shows the priority valvein the free-flow position. The flow of fluid movesthe poppet to the left, the poppet springcompresses, and the poppet unseats. This allowsfree flow of fluid through the valve.

VALVE MANIFOLDS

Sometimes suction must be taken from one ofmany sources and discharged to another unit orunits of either the same or another group. A valvemanifold is used for this type of operation. Anexample of such a manifold (fig. 6-14) is the fuel

Figure 6-14.—Valve manifold showing cutaway view of the valves and typical combination of suction and discharge valves.

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oil filling and transfer system where provisionmust be made for the transfer of oil from any tankto any other tank, to the service system, or toanother ship. If, for example, the purpose is totransfer oil from tank No. 1 to tank No. 4, thedischarge valve for tank No. 4 and the suctionvalve from tank No. 1 are opened, and all othervalves are closed. Fuel oil can now flow from tankNo. 1, through the suction line, through thepump, through the discharge valve, and into tankNo. 4. The manifold suction valves are often ofthe stop-check type to prevent draining of pumpswhen they are stopped.

VALVE HANDWHEELIDENTIFICATION ANDCOLOR CODING

Valves are identified by markings inscribed onthe rims of the handwheels, by a circular labelplate secured by the handwheel nut, or by labelplates attached to the ship’s structure or to theadjacent piping.

Piping system valve handwheels and operatinglevers are marked for training and casualtycontrol purposes with a standardized color code.Color code identification is in conformance withthe color scheme of table 6-1. Implementation ofthis color scheme provides uniformity among allnaval surface ships and shore-based trainingfacilities.

MAINTENANCE

Preventive maintenance is the best wayto extend the life of valves and fittings.Always refer to the applicable portion of theStandard Navy Valve Technical Manual, NAV-SEA 0948-LP-012-5000, if possible. When makingrepairs on more sophisticated valve types, use theavailable manufacturer’s technical manuals. Assoon as you observe a leak, determine the cause,and then apply the proper corrective maintenance.Maintenance may be as simple as tightening apacking nut or gland. A leaking flange joint mayneed only to have the bolts tightened or to havea new gasket or O-ring inserted. Dirt and scale,if allowed to collect, will cause leakage. Loosehangers permit sections of a line to sag, and theweight of the pipe and the fluid in these saggingsections may strain joints to the point of leakage.

Whenever you are going to install a valve, besure you know the function the valve is going toperform-that is, whether it must start flow, stopflow, regulate flow, regulate pressure, orprevent backflow. Inspect the valve body for theinformation that is stamped upon it by the

Table 6-1.—Valve Handwheel Color Code

manufacturer: type of system (oil, water, gas),operating pressure, direction of flow, and otherinformation.

You should also know the operatingcharacteristics of the valve, the metal from whichit is made, and the type of end connection withwhich it is fitted. Operating characteristics andthe material are factors that affect the length andkind of service that a valve will give; endconnections indicate whether or not a particularvalve is suited to the installation.

When you install valves, ensure they arereadily accessible and allow enough headroom forfull operation. Install valves with stems pointingupward if possible. A stem position betweenstraight up and horizontal is acceptable, but avoidthe inverted position (stem pointing downward).If the valve is installed with the stem pointingdownward, sediment will collect in the bonnet andscore the stem. Also, in a line that is subject tofreezing temperatures, liquid that is trapped in thevalve bonnet may freeze and rupture it.

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Since you can install a globe valve withpressure either above the disk or below the disk(depending on which method will be best for theoperation, protection, maintenance, and repair ofthe machinery served by the system), you shoulduse caution. The question of what would happenif the disk became detached from the stem is amajor consideration in determining whetherpressure should be above the disk or below it. Ifyou are required to install a globe valve, be SUREto check the blueprints for the system to see whichway the valve must be installed. Very seriouscasualties can result if a valve is installed withpressure above the disk when it should be belowthe disk, or below the disk when it should beabove.

Valves that have been in constant service for along time will eventually require gland tightening,repacking, or a complete overhaul of all parts. Ifyou know that a valve is not doing the job forwhich it was intended, dismantle the valve andinspect all parts. You must repair or replace alldefective parts.

The repair of globe valves (other than routinerenewal of packing) is limited to refinishing the

seat and/or disk surface. When doing this work,you should observe the following precautions:

When refinishing the valve seat, do not re-move more material than is necessary. Youcan finish valves that do not have replace-able valve seats only a limited number oftimes.

Before doing any repair to the seat and diskof a globe valve, check the valve disk tomake certain it is secured rigidly to and issquare on the valve stem. Also, check to besure that the stem is straight. If the stem isnot straight, the valve disk cannot seatproperly.

Carefully inspect the valve seat and valvedisk for evidence of wear, for cuts on theseating area, and for improper fit of thedisk to the seat. Even if the disk and seatappear to be in good condition, you shouldperform a spot-in check to find outwhether they actually are in goodcondition.

Figure 6-15 shows a standard checkoffdiagram for performing a routine inspection andminor maintenance of a valve.

Figure 6-15—Valve maintenance checkoff diagram.

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Spotting-In Valves

The method used to visually determinewhether the seat and the disk of a valve makegood contact with each other is called spotting-in. To spot-in a valve seat, you first apply a thincoating of Prussian blue (commonly called BlueDykem) evenly over the entire machined facesurface of the disk. Insert the disk into the valveand rotate it one-quarter turn, using a lightdownward pressure. The Prussian blue will adhereto the valve seat at those points where the diskmakes contact. Figure 6-16 shows the appearanceof a correct seat when it is spotted-in; it also showsthe appearance of various kinds of imperfectseats.

After you have noted the condition of the seatsurface, wipe all the Prussian blue off the diskface surface. Apply a thin, even coat of Prussianblue to the contact face of the seat and place thedisk on the valve seat again and rotate the diskone-quarter turn. Examine the resulting blue ringon the valve disk. The ring should be unbrokenand of uniform width. If the blue ring is brokenin any way, the disk is not making propercontact with the seat.

Grinding-In Valves

The manual process used to remove smallirregularities by grinding together the contactsurfaces of the seat and disk is called grinding-in. Grinding-in should not be confused withrefacing processes in which lathes, valve reseatingmachines, or power grinders are used to re-condition the seating surfaces.

Figure 6-16.—Examples of spotted-in valve seats.

To grind-in a valve, first apply a light coatingof grinding compound to the face of the disk.Then insert the disk into the valve and rotate thedisk back and forth about one-quarter turn; shiftthe disk-seat relationship from time to time so thedisk will be moved gradually, in incrementsthrough several rotations. During the grindingprocess, the grinding compound will gradually bedisplaced from between the seat and disk surfaces;therefore, you must stop every minute or so toreplenish the compound. When you do this, wipeboth the seat and the disk clean before applyingthe new compound to the disk face.

When you are satisfied that the irregularitieshave been removed, spot-in the disk to the seatin the manner previously described.

Grinding-in is also used to follow up allmachining work on valve seats or disks. When thevalve seat and disk are first spotted-in after theyhave been machined, the seat contact will be verynarrow and will be located close to the bore.Grinding-in, using finer and finer compounds asthe work progresses, causes the seat contact tobecome broader. The contact area should be aperfect ring covering about one-third of theseating surface.

Be careful to avoid overgrinding a valve seator disk. Overgrinding will produce a groove in theseating surface of the disk; it will also roundoff the straight, angular surface of the disk.Machining is the only process by which over-grinding can be corrected.

Lapping Valves

When a valve seat contains irregularities thatare slightly larger than can be satisfactorilyremoved by grinding-in, the irregularities can beremoved by lapping. A cast-iron tool (lap) ofexactly the same size and shape as the valve diskis used to true the valve seat surface. The follow-ing are some precautions you should follow whenlapping valves:

Do not bear heavily on the handle of thelap.

Do not bear sideways on the handle of thelap.

Change the relationship between the lapand the valve seat occasionally so that thelap will gradually and slowly rotate aroundthe entire seat circle.

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Keep a check on the working surface ofthe lap. If a groove develops, have the laprefaced.

Always use clean compound for lapping.

Replace the compound frequently.

Spread the compound evenly and lightly.

Do not lap more than is necessary toproduce a smooth even seat.

Always use a fine grinding compound tofinish the lapping job.

Upon completion of the lapping job, spot-in and grind-in the disk to the seat.

You should use only approved abrasivecompounds for reconditioning valve seats anddisks. Compounds for lapping valve disks andseats are supplied in various grades. Use a coarsegrade compound when you find extensivecorrosion or deep cuts and scratches on the disksand seats. Use a medium grade compound as afollow-up to the coarse grade; you may also useit to start the reconditioning process on valves thatare not too severely damaged. Use a fine gradecompound when the reconditioning process nearscompletion. Use a microscopic-fine grade forfinish lapping and for all grinding-in.

Refacing Valves

Badly scored valve seats must be refaced ina lathe, with a power grinder, or with a valvereseating machine. However, the lathe, ratherthan the reseating machine, should be used forrefacing all valve disks and all hard-surfaced valveseats. Work that must be done on a lathe or witha power grinder should be turned over to shoppersonnel.

Repacking Valves

If the stem and packing of a valve are in goodcondition, you can normally stop packing glandleaks by tightening up on the packing. You mustbe careful, however, to avoid excessive threadengagement of the packing gland studs (if used)and to avoid tightening old, hardened packingwhich will cause the valve to seize. Subsequentoperation of such a valve may score or bend thestem.

Coils, rings, and corrugated ribbon are thecommon forms of packing used in valves. Theform of packing to be used in repacking aparticular valve will depend on the valve size,application, and type. Packing materials will bediscussed in tnore detail later in this chapter.

STEAM TRAPS

Steam traps are installed in steam lines to draincondensate from the lines without allowing theescape of steam. There are many different designsof steam traps; some are suitable for high-pressureuse and others for low-pressure use.

TYPES OF STEAM TRAPS

Some types of steam traps that are used in theNavy are the mechanical steam traps, bimetallicsteam traps, and orifice-type steam traps.

Mechanical Steam Traps

Mechanical steam traps in common use in-clude bucket-type traps and ball-float traps.

The operation of the bucket-type steam trap,shown in figure 6-17, is controlled by the

Figure 6-17.—Bucket-type steam trap.

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condensate level in the trap body. The bucketvalve is connected to the bucket in such a way thatthe valve closes as the bucket rises. As condensatecontinues to flow into the trap body, the valveremains closed until the bucket is full. When thebucket is full, it sinks and thus opens the valve.The valve remains open until enough condensatehas blown out to allow the bucket to float, thusclosing the valve.

Figure 6-18 shows a ball-float steam trap. Thistrap works much in the same way as the buckettrap. Condensate and steam enter the body of thetrap, and the condensate collects at the bottom.As the condensate level rises, the ball float risesuntil it is raised enough to open the outlet valveof the trap. When the outlet valve opens, thecondensate flows out of the trap into the drainsystem, and the float level drops, shutting off thevalve until the condensate level rises again.

Bimetallic Steam Traps

Bimetallic steam traps of the type shown infigure 6-19 are used in many ships to draincondensate from main steam lines, auxiliary steamlines, and other steam components. The mainworking parts of this steam trap are a segmentedbimetallic element and a ball-type check valve.

The bimetallic element has several bimetallicstrips fastened together in a segmented fashion,as shown in figure 6-19. One end of the bimetallicelement is fastened rigidly to a part of the valvebody; the other end, which is free to move, is

Figure 6-18.—Hall-float steam trap.

Figure 6-19.—Bimetallic steam trap.

fastened to the top of the stem of the ball-typecheck valve.

Line pressure acting on the check valve keepsthe valve open. When steam enters the trap body,the bimetallic element expands unequally becauseof the different response to the temperature ofthe two metals; the bimetallic element deflects up-ward at its free end, thus moving the valve stemupward and closing the valve. As the steam coolsand condenses, the bimetallic element movesdownward, toward the horizontal position, thusopening the valve and allowing some condensateto flow out through the valve. As the flow ofcondensate begins, an unbalance of line pressureacross the valve is created; since the line pressureis greater on the upper side of the ball of the checkvalve, the valve now opens wide and allows a fullcapacity flow of condensate.

Orifice Steam Traps

Aboard ship, continuous-flow steam traps ofthe orifice type are used in systems or services inwhich condensate forms at a fairly steady rate.Figure 6-20 shows one orifice-type steam trap.

Several variations of the orifice-type steamtrap exist, but all have one thing in common-they have no moving parts. One or more restrictedpassageways or orifices allow condensate to tricklethrough but do not allow steam to flow through.Besides orifices, some orifice-type steam trapshave baffles.

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Figure 6-20.—Constant-flow drain orifice.

MAINTENANCE

A strainer is installed just ahead of each steamtrap. The strainer must be kept clean and in goodcondition to keep scale and other foreign matterfrom getting into the trap. Scale and sediment canclog the working parts of a steam trap andseriously interfere with the working of the trap.

Steam traps that are not operating properlycan cause problems in systems and machinery.One way to check on the operation of a steam trapis to listen to it. If the trap is leaking, you willprobably be able to hear it blowing through.Another way to check the operation of steam trapsis to check the pressure in the drain system. Aleaking steam trap causes an unusual increase inpressure in the drain system. When observing thiscondition, you can locate the defective trap bycutting out (isolating from the system) traps, oneat a time, until the pressure in the drain systemreturns to normal.

You should disassemble, clean, and inspectdefective steam traps. After determining the causeof the trouble, repair or replace parts as required.In some steam traps, you can replace the mainworking parts as a unit; in others, you may haveto grind in a seating surface, replace a disk, orperform other repairs. You should reseat defectivetrap discharge valves. Always install new gasketswhen reassembling steam traps.

FILTERS AND STRAINERS

Fluids are kept clean in a system principallyby devices such as filters and strainers. Magnetic

plugs (fig. 6-21) also are used in some strainersto trap iron and steel particles carried by fluid.Studies have indicated that even particles as smallas 1 to 5 microns have a degrading effect, causingfailures and hastening deterioration in many cases.

There will always be controversy over theexact definitions of filters and strainers. In thepast, many such devices were named filters buttechnically classed as strainers. To minimizethe controversy, the National Fluid PowerAssociation gives us these definitions:

FILTER—A device whose primary functionis the retention, by some porous medium, ofinsoluble contaminants from a fluid.

STRAINER—A coarse filter.

To put it simply, whether the device is a filteror a strainer, its function is to trap contaminantsfrom fluid flowing through it. “Porous medium”simply refers to a screen or filtering material thatallows fluid flow through it but stops variousother materials.

MESH AND MICRON RATINGS

Filters, which may be made of many materialsother than wire screen, are rated by MICRONsize. A micron is one-millionth of a meter or39-millionths of an inch. For comparison, a grainof salt is about 70 microns across. The smallestparticle visible to the naked eye is about

Figure 6-21.—Magnetic plugs.

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Figure 6-22.—Relationship of micron sizes.

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40 microns. Figure 6-22 shows the relationship ofthe various micron sizes with mesh and standardsieve sizes.

A simple screen or a wire strainer is rated forfiltering “fineness” by a MESH number or itsnear equivalent, STANDARD SIEVE number.The higher the mesh or sieve number, the finerthe screen.

When a filter is specified as so many microns,it usually refers to the filter’s NOMINAL rating.A filter nominally rated at 10 microns, forexample, would trap most particles 10 microns insize or larger. The filter’s ABSOLUTE rating,however, would be a somewhat higher size,perhaps 25 microns. The absolute rating is the sizeof the largest opening or pore in the filter.Absolute rating is an important factor only whenit is mandatory that no particles above a givensize be allowed to circulate in the system.

Figure 6-23.—Inlet line filter.

FILTER/STRAINER LOCATION

There are three general areas in a system forlocating a filter; the inlet line, the pressure line,or a return line. Both filters and strainers areavailable for inlet lines. Filters are normallyused in other lines.

Inlet Filters and Strainers

Figure 6-23 shows the location of an inletline filter. An inlet line filter is usuallya relatively coarse mesh filter. A fine meshfilter (unless it is very large) creates morepressure drop than can be tolerated in aninlet line.

Figure 6-24 shows a typical strainer of the typeinstalled on pump inlet lines inside a reservoir.It is relatively coarse as filters go, beingconstructed of fine mesh wire. A 100-meshstrainer protects the pump from particles aboveabout 150 microns in size.

Pressure Line Filters

A number of filters are designed forinstallation right in the pressure line (fig. 6-25)and can trap much smaller particles than inletline filters. Such a filter might be used wheresystem components, such as valves, are lessdirt-tolerant than the pump. The filter thuswould trap this fine contamination from thefluid as it leaves the pump. Pressure linefilters must be able to withstand the operatingpressure of the system.

Figure 6-24.—Inlet strainer. Figure 6-25.—Pressure line filter.

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Return Line Filters

Return line filters (fig. 6-26) also can trap verysmall particles before the fluid returns to thereservoir/tank. They are particularly useful insystems which do not have large reservoirs/tanksto allow contaminants to settle out of the fluid.A return line filter is nearly a must in a systemwith a high-performance pump, which has veryclose clearances and usually cannot be sufficientlyprotected by an inlet line filter.

FILTER/STRAINER MATERIALS

The materials used in filters and strainers areclassified as mechanical, absorbent, or adsorbent.

Figure 6-26.—Return line filter.

Most strainer material is of the mechanical typewhich operates by trapping particles betweenclosely woven metal screens and/or disks, andmetal baskets. The mechanical type of materialis used mostly where the particles removed fromthe medium are of a relatively coarse nature.

Absorbent filters are used for most minute-particle filtration in fluid systems. They are madeof a wide range of porous materials, includingpaper, wood pulp, cotton, yarn, and cellulose.Paper filters are usually resin-impregnated forstrength.

Adsorbent (or active) filters, such as charcoaland Fuller’s earth, are used mostly in gaseous orvapor systems. This type of filter material shouldnot be used in hydraulic systems since they removeessential additives from the hydraulic fluid.

CONSTRUCTION OFFILTER ELEMENTS

Filter elements are constructed in variousways. The three most common filter elementconstruction types are the surface-type (mostcommon), the depth-type, and the edge-type.

Surface-type filter elements (fig. 6-27) aremade of closely woven fabric or treated paper withpores to allow fluid to flow through. Veryaccurate control of the pore size is a feature ofthe surface-type elements.

A depth-type filter element (fig. 6-28) iscomposed of layers of a fabric or fibers whichprovide many tortuous paths for the fluid to flow

Figure 6-27.—Filler assembly using a surface-type element. Figure 6-28.—Depth-type filter element.

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through. The pores or passages vary in size, andthe degree of filtration depends on the flow rate.Increases in flow rate tend to dislodge trappedparticles. This filter is limited to low-flow, lowpressure-drop conditions.

An edge-type filter element (fig. 6-29)separates particles from fluids passing betweenfinely spaced plates. The filter shown featuresstationary cleaner blades that scrape out thecollected contaminants when the handle is twistedto turn the element.

TYPES OF FILTERS

In this section we will discuss the various filters(simplex, duplex, full flow, proportional flow,and indicator) that you will most frequently findinstalled in equipment.

Simplex Filter

The simplex filter has one or more cylindricallyshaped fine mesh screens or perforated metalsheets. The size of the opening in the screens orthe perforated metal sheets determines the size ofparticles filtered out of the fluid. The design ofthis type of filter is such that total flow must passthrough a simplex filter.

Figure 6-29.—Edge-type filter element.

Duplex Filters

Duplex filters are similar to simplex filtersexcept in the number of elements and in provisionfor switching the flow through either element. Aduplex filter may consist of a number of singleelement filters arranged in parallel operation, orit may consist of two or more filters arrangedwithin a single housing. The full flow can bediverted, by operation of valves, through anysingle element. The duplex design is mostcommonly used in fuel or hydraulic systemsbecause the ability to shift to an offline filter whenthe elements are cleaned or changed is desirablewithout the system being secured.

Full-Flow Filters

The term full-flow applied to a filter meansthat all the flow into the filter inlet port passesthrough the filtering element. In most full-flowfilters, however, there is a bypass valve preset toopen at a given pressure drop and divert flow pastthe filter element. This prevents a dirty elementfrom restricting flow excessively. Figure 6-30shows a full-flow filter. Flow, as shown, is out-to-in; that is, from around the element throughit to its center. The bypass opens when total flowcan no longer pass through the contaminatedelement without raising the system pressure. Theelement is replaceable after removing a single bolt.

Figure 6-30.—Full-flow filter.

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Proportional-Flow Filters

A proportional-flow filter (fig. 6-31) may usethe Venturi effect to filter a portion of the fluidflow. The fluid can flow in either direction. Asit passes through the filter body, a venturi throatcauses an increase in velocity and a decrease inpressure. The pressure difference forces some ofthe fluid through the element to rejoin the mainstream at the venturi. The amount of fluid filteredis proportional to the flow velocity. Hence thename proportional-flow filter.

Indicating Filters

Indicating filters are designed to signal theoperator when the element needs cleaning. Thereare various types of indicators, such as color-coded, flag, pop-up, and swing arm. Figure 6-32shows a color-coded indicating filter. The elementis designed so it begins to move as the pressureincreases due to dirt accumulation. One end islinked to an indicator that shows the operator just

how clean or dirty the element is. Another featureof this type of filter is the ease and speed withwhich the element can be removed and replaced.Most filters of this kind are designed for inlet lineinstallation.

Filter/Separator

The filter/separator is a two-stage unitconsisting of a coalescer stage and a separatorstage within a single housing. Each stage is madeup of replaceable elements, the number of whichis determined by such considerations as thecapacity of the elements in gallons per minute(gpm) and the elements dirt retaining properties.Coalescer elements filter solids from the fluid andcause small particles of undissolved water tocombine (coalesce) into larger drops of water that,because of their weight, will settle in thefilter/separator sump. Separator elements areprovided to remove any remaining free water thathas not coalesced. Water that accumulates in the

Figure 6-31.—Proportional-flow filter.

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any substantial increase in the overall size andweight of the unit.

Type of Construction

Surface heat exchangers are often givennames that indicate general features of design andconstruction. Basically, all surface heat ex-changers are of SHELL-AND-TUBE construc-tion. However, the shell-and-tube arrangement ismodified in various ways and in some cases it isnot easy to recognize the basic design. Shell-and-tube heat exchangers include such types as(1) straight tube, (2) U-bend tube, (3) helical orspiral tube, (4) double tube, (5) strut tube, and(6) plate tube heat exchangers.

STRAIGHT TUBE.—In straight tube heatexchangers, the tubes are usually arranged in abundle and enclosed in a cylindrical shell. Theends of the tubes may be expanded into a tubesheet at each end of the bundle, or they may beexpanded into one tube sheet and packed andferruled into the other. The ferrules allow the tubeto expand and contract slightly with temperaturechanges.

U-BEND TUBE.—U-bend tube heat ex-changers, sometimes called RETURN BEND heatexchangers, have a bundle of U-shaped tubesinside a shell. Since the tubes are U-shaped, thereis only one tube sheet. The shape of the tubesprovides enough allowance for expansion andcontraction.

HELICAL OR SPIRAL TUBE.—Helical orspiral tube heat exchangers have one or more coilsof tubing installed inside a shell. The tubes maycommunicate with headers at each end of the shellor, if a relatively simple unit, the ends of thetubing may pass through the shell and serve as theinlet and the outlet for the fluid that flows throughthe coil of tubing.

DOUBLE TUBE.—Double tube heat ex-changers have one tube inside another. One fluidflows through the inner tube and the other fluidflows between the outer and inner tubes. Theouter tube may thus be regarded as the shell foreach inner tube. The shells, or outer tubes, areusually arranged in banks and are connected atone end by a common tube sheet with apartitioned cover that serves to direct theflow. Many double tube heat exchangers are ofU-bend construction to allow for expansion and

contraction. The fuel oil service/transfer heaters,commonly used by the Navy, are examples of adouble tube heat exchanger.

STRUT TUBE AND PLATE TUBE.—Struttube and plate tube heat exchangers are noticeablydifferent in design from the other shell-and-tubeheat exchangers. The tubes in both strut tube andplate tube heat exchangers consist of pairs of flat,oblong strips; one fluid flows inside the tubes andthe other flows around the outside. Strut tube andplate tube heat exchangers are used primarily aswater coolers and lubricating oil coolers ininternal-combustion engines; they are also usedas lube oil coolers for start air compressors.

Direction of Flow

In surface heat exchangers the fluids may flowparallel to each other, counter to each other, orat right angles to each other.

PARALLEL FLOW.—In parallel flow (fig.6-33), both fluids flow in the same direction. Ifa parallel flow heat exchanger has a lengthy heattransfer surface, the temperatures of the twofluids will be practically equal as the fluids leavethe heat exchanger.

COUNTERFLOW.— In counterflow (fig.6-34), the two fluids flow in opposite directions.Counterflow heat exchangers are used in manyapplications that require large temperaturechanges in the cooled or heated fluids. Fuel oilheaters, lube oil coolers, and many internal-combustion engine coolers are examples of thistype.

CROSSFLOW.—In crossflow (fig. 6-35), onefluid flows at right angles to the other. Crossflowis particularly useful for removing latent heat,thus condensing a vapor to a liquid. Counterflow

Figure 6-33.—Parallel flow in heat exchanger.

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Figure 6-32.—Color-coded indicating filter.

filter/separator sump is removed through a drainline, either automatically or manually.

In-Line or Cone Filter

In-line or cone filters have conical-shaped finemesh screen or perforated metal sheet that isinserted into the system pipe and secured by a setof flanges. Its system application determineswhether it is considered a filter or strainer. It ismost commonly used in seawater systems, whereit is considered a strainer. This type of filter isprohibited in fuel systems.

MAINTENANCE

Proper operation of filters, strainers, and filterseparators is essential for satisfactory gas turbineand diesel engine performance. Besides cloggingthe systems with foreign matter, continuedoperation with unfiltered fluids results inaccelerated pump wear and system degradation.Routine maintenance of filters, strainers, andfilter/separators is adequately covered in NavalShips’ Technical Manual, Chapter 541,“Petroleum Fuel Stowage, Use, and Testing,”paragraphs 541-8.51 through 541-8.59.

HEAT EXCHANGERS

Any device or apparatus designed to allow thetransfer of heat from one fluid (liquid or gas) to

another fluid is a heat exchanger. Distilling plants,MRG lube oil coolers, fuel oil transfer heaters,and fuel oil service heaters are primary examplesof heat exchangers; in common usage, however,they are not referred to as heat exchangers.

For heat to transfer from one substance toanother, a difference in the temperature of thetwo substances must exist. Heat flow or heattransfer can occur only from a substance that isat a higher temperature to a substance that is ata lower temperature. When two objects that areat different temperatures are placed in contactwith one another, or near each other, heat willflow from the warmer object to the cooler oneuntil both objects are at the same temperature.Heat transfer occurs at a faster rate when thereis a large temperature difference than when thereis only a slight temperature difference. As thetemperature difference approaches zero, the rateof heat flow also approaches zero.

In some heat exchangers we want to RAISETHE TEMPERATURE of one fluid. Fuel oilheaters, combustion air preheaters, lube oilheaters, and many other heat exchangers usedaboard ship serve this function.

In other heat exchangers, we want to LOWERTHE TEMPERATURE of one fluid. Lube oilcoolers, start air coolers, and bleed air coolers areexamples of this type of heat exchanger.

In this section we describe some of the heatexchangers that you will find in the engineeringspaces.

CLASSIFICATION OFHEAT EXCHANGERS

Heat exchangers may be classified accordingto the path of heat flow, the relative direction ofthe flow of the fluids, the number of times eitherfluid passes the other fluid, and the generalconstruction features, such as the type of surfaceand the arrangement of component parts. Thetypes of heat exchangers in common use in navalships are described in the following sections bythese basic methods of classification.

Type of Surface

Surface heat exchangers are known as PLAINSURFACE units if the surface is relativelysmooth, or as EXTENDED SURFACE units ifthe surface is fitted with rings, fins, studs, or someother kind of extension. The main advantage ofthe extended surface unit is that the extensionsincrease the heat transfer area without requiring

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Figure 6-34.—Counterflow in heat exchanger.

Figure 6-35.—Crossflow in heat exchanger.

and crossflow heat exchangers are more com-monly used than the parallel flow aboard ship.In many heat exchangers, the types of flow arecombined in various ways so it is not always easyto determine whether the flow is basically parallel,counter, or cross.

Number of Passes

Surface heat exchangers may be classified asSINGLE-PASS units if one fluid passes anotheronly once, or as MULTIPASS units if one fluidpasses another more than once. Multipass flowis obtained by the arrangement of the tubes andthe fluid inlets and outlets or by the use of baf-fles to guide a fluid so it passes the other fluidmore than once before it leaves the heatexchanger.

Path of Heat Flow

When classified according to the path of heatflow, heat exchangers are of two basic types. Inthe INDIRECT or SURFACE heat exchanger, theheat flows from one fluid to the other througha tube, plate, or other surface that separates thetwo fluids; in the DIRECT-CONTACT heat

exchanger, the heat is transferred directly fromone fluid to another as the two fluids mix.Practically all heat exchangers used aboard Navyships are of the indirect or surface type.

MAINTENANCE OFHEAT EXCHANGERS

Foreign matter lodged on or in the tubes ofa heat exchanger interferes with and reduces therate of heat transfer from one fluid to the other.Heat exchangers requiring the most attention arethose where the cooling medium is seawater.Marine growth can form on the tube surfaces and,in extreme cases, completely block the flow.

The seawater side of the tubes should becleaned as often as necessary. The intervals willdepend on the rate that slime, marine growth,scale, mud, oil, grease, and so forth, are depositedon the tube walls. The amount of such depositsdepends on the operating environment andexisting conditions. Operation in shallow water,for example, may cause rapid fouling of the tubes.

The resistance of heat exchanger tubes tocorrosion depends on a thin, adherent, continuousfilm of corrosion products on the surface exposedto seawater; therefore, you must be extremelycareful when cleaning the tubes not to use abrasivetools capable of marring or scratching the surfaceof the tubes. You should never use wire brushesor rubber plugs having metal parts inside con-denser tubes. Any scratch or perforation of thecorrosion-resistant film will form a pit that willwiden and deepen. Eventually this can result intube failure (through corrosion pitting), in thesame manner as occurs when foreign matterlodges on the tube surface.

For ordinary cleaning, push an air lancethrough each tube, wash the tube sheets clean, andremove all foreign matter from the water chests.In installations with severe fouling, push a waterlance through each tube to remove foreign matter.For extreme fouling, you should run a rotatingbristle brush through each tube-or drive softrubber plugs, available at shipyards, through thetubes by using air or water pressure. Afterwards,ensure this procedure is followed by water-lancing.

ZINCS

Where zinc anodes are required to protect theheat exchanger materials from electrolysis, goodmetallic contact must exist between the anodesand the metal of the condenser.

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A casual inspection of a badly scaled zincanode, especially while it is still wet, may leadpersonnel to believe that the metal is exposedinstead of the scale. The anode, even though itappears to be in good condition, should be cleanedwith a chipping hammer to learn the truecondition of the metal. Whenever zincs areinspected or cleaned, check the condition of themetallic contact between the anode and itssupport.

PIPING

The control and application of fluid powerwould be impossible without a suitable means ofconveying the fluid from the power source to thepoint of application. Fluid lines used for thispurpose are called piping. They must be designedand installed with the same care applicable toother components of the system. To obtain thisdesired result, attention must be given to thevarious types, materials, and sizes of linesavailable for the fluid power system. The differenttypes of lines and their application to fluid powersystems are described in the first part of thissection. The last part of this section is devotedto the various connectors applicable to thedifferent types of fluid lines.

IDENTIFICATION OF PIPING

The three most common lines used in fluidpower systems are pipe, tubing, and flexible hose.They are sometimes referred to as rigid (pipe),semirigid (tubing), and flexible piping. Incommercial usage, there is no clear distinctionbetween piping and tubing, since the correctdesignation for each product is established by themanufacturer. If the manufacturer calls itsproduct pipe, it is pipe; if the manufacturer calls ittubing, it is tubing.

In the Navy, however, a distinction is madebetween pipe and tubing. The distinction is basedon the method used to determine the size of theproduct. There are three important dimensionsof any tubular product-outside diameter (OD),inside diameter (ID), and wall thickness. Theproduct is called tubing if its size is identified byactual measured outside diameter and by actualwall thickness. The product is called pipe if itssize is identified by a nominal dimension and wallthickness.

PIPING MATERIALS

The pipe and tubing used in fluid systemstoday are commonly made from steel, copper,brass, aluminum, and stainless steel. The hose

assemblies are constructed of rubber or Teflon®.Each of these materials has its own distinctadvantages or disadvantages, depending upon itsapplication.

Steel piping and tubing are relatively in-expensive, have a high tensile strength, are suitablefor bending and flanging, and are very adaptableto high pressures and temperatures. Its chiefdisadvantage is a comparatively low resistance tocorrosion.

Copper and brass piping and tubing have ahigh resistance to corrosion and are easily drawnor bent. Pipe or tubing made from these materialsis unsuitable for systems with high temperatures,stress, or vibration because they have a tendencyto harden and break.

Aluminum has many characteristics andqualities required for fluid systems. It has a highresistance to corrosion, is lightweight, is easilydrawn or bent, and (when combined with certainalloys) will withstand high pressures andtemperatures.

Stainless steel piping or tubing is relativelylightweight and is used in a system that will beexposed to abrasion, high pressure, and intenseheat. Its main disadvantage is high cost.

FLEXIBLE HOSE ASSEMBLIES

The flexible hose assembly is a specific typeof flexible device that uses reinforced rubber hose

Figure 6-36.—90° and 180° flexible hose configurations.

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and metal end fittings. It is used to absorbmotions between resiliently mounted machineryand fixed or resiliently mounted piping systems.The motions to be considered may be of eitherrelatively large size due to high-impact shock orof smaller size due to the vibratory forces ofrotating machinery. The configuration selectedmust contain enough hose to accommodate shockand vibratory motions without stressing the hoseassembly or machinery to an unacceptable degree.

Approved Flexible HoseConfigurations

The arrangements (or configurations) deter-mined to give the best noise attenuationcharacteristics and to accommodate the motionsof resiliently mounted equipment are shown infigures 6-36 and 6-37. The 90° “L” con-figuration (dogleg) is the preferred configuration;however, where space and piping arrangement

Figure 6-37.—Other approved single hose length configurations.

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prohibit the use of the “L” configuration, a 180°or “U” configuration may be used. The 90° “L°and 180° “U” configurations are shown assketches A and B of figure 6-36.

A configuration that uses a single length ofhose bent to about 90° is approved where the hosedoes not bend below its specified minimumbending radius when the equipment moves to themaximum limits allowed by its mounts (view Aof fig. 6-37). The straight single hose con-figuration and the 180° single hose bend (view Bof fig. 6-37) are also approved for use where thehose size is less than 1 inch ID.

Flexible connections that use rubber hose arenot used in systems where the maximum con-tinuous operating temperature is in excess of200°F.

Hose Identification

Hose is identified by the manufacturer’s partnumber and the size or dash number. The dashnumber is the nominal hose inside diameter in six-teenths of an inch. Hose built to militaryspecification (MILSPEC) requirements have thenumber of the specification and, where applicable,the class of hose, the quarter and year ofmanufacture, and the manufacturer’s trade-mark. This information is molded or otherwisepermanently repeated periodically on the hosecover (sometimes referred to as the “lay linemarking”). Other information permanentlymarked on the hose cover is the manufacturer’scode and the date of manufacture. Forinterpretations of commercial lay line markings,refer to the appropriate manufacturer’s catalogor manual.

Fitting Identification

Use special care in identifying hose fittingsbecause their designation is more complex thanhose. A fitting suitable for connecting to a givenhose size can end in more than one size and typeof connection to the piping. A fitting, therefore,must be identified by the manufacturer’s partnumber, the size of the end connection thatjoins the piping system, and the dash sizeto show the size hose to which it makes up. Forinterpretation of manufacturer markings, consultthe appropriate manufacturer’s manual. Fittings

meeting military specification requirements havethe specification number, class of fitting (whereapplicable), type, size, and manufacturer’strademark.

A cross index between the manufacturers’designations and military specifications andinformation to correctly identify approved hosesand fittings can be found in Piping Devices,Flexible Hose Assemblies, volume 1, NAVSEAS6430-AE-TED-010.

Inspection of Hose and FittingsPrior To Make-Up

The basic inspection methods for hose andfittings are listed as follows:

1.

2.

3.

4.

5.

6.

Ensure that the hose and couplings are thecorrect ones for the intended use andthat the age of the rubber hose does notexceed a shelf life of 4 years. Teflon® andmetal hose have no limiting shelf life.Inspect for signs that the hose has beentwisted. Use the hose lay line for a guideto determine whether or not any twist ispresent. If twisted, reject.Inspect for signs that the hose has beenkinked or bent beyond its minimum bendradius. If suspect, reject.Inspect for signs of loose inner liner. Iffound, cut the-hose to see if this conditionexists throughout the entire length. Ifsuspect, reject.Visually check the inner liner and outerrubber cover of the hose for breaks,hairline cuts, or severe abrasions. Ifany suspect areas are found, reject.Inspect the fittings for defects, suchas cracked nipples and damaged threads.If suspect, or if defects are found, reject.

Procedures for making up hoses and fittingscan also be found in the Naval Ships’ TechnicalManual, chapter 505, or the appropriatemanufacturer’s catalog or manual, and are notcovered here due to the many types available.

Visual Inspection

After assembling the hose and fittings, visuallyinspect the entire configuration to ensure thefollowing:

1. The hose inner liner and outer cover isintact and contains no cuts or harmfulabrasions.

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2. The hose has not been twisted (check thelay line).

3. The circumferential chalk line on the hosenext to the coupling has been drawn beforethe hydrostatic test.

4. The internal spring (if installed) is evenlyspaced and flat against the inner liner.Ensure a gap exists between one of the endfittings and the end of the spring.

Hydrostatic Test

Upon completion of visual inspection,hydrostatically shop test the hose assembly withfresh water. For each style and size hose, test thepressure to ensure that it is twice the maximumallowable pressure shown in chapter 505 of NavalShips’ Technical Manual. When you test pressure,hold for not more than 5 minutes nor less than60 seconds. When test pressure is reached, visuallyinspect the hose assembly for the followingdefects:

1. Leaks or signs of weakness2. Twisting of the hose (this indicates that

some twist existed before pressure wasapplied)

3. Slippage of the hose out of the coupling(a circumferential chalk line can helpdetermine this)

If any of the above occurs, reject the assembly.

CAUTION

Do not confuse hose elongation underpressure with coupling slippage. If thechalk line returns to near its originalposition, no slippage has occurred and theassembly is satisfactory. If there is anydoubt, perform a second test. If doubtpersists after the second test, reject theassembly.

Air Test

Hose assemblies intended for gas or airservice must also be tested with air or nitrogenat 100 psi and the assembly immersed in water.Random bubbles may appear over the hose andin the fitting area when the assembly is first

pressurized. Do not construe this as a defect.However, if the bubbles persist in forming at asteady rate at any particular point on the hose,reject the assembly.

Installation of FlexibleHose Assemblies

After completion of tests, proceed asfollows:

1.

2.

3.

4.

Install as soon as possible.

Do not leave the hose assembly around ondecks or on docks where they can besubjected to any form of abuse.

Make up hose assemblies as late aspossible during the availability schedule tominimize the chances of damage while theship is being overhauled.

Install plastic dust caps, plugs, or tape endsto protect threaded areas until the hoseassembly is installed.

When installing flexible base connections,observe the following requirements:

1. Ensure each leg of hose is free of twistbetween end fittings.

2. Ensure the fixed piping near the flexibleconfiguration is properly supported so thatit does not vibrate from the resilientlymounted equipment.

3. Ensure the configurations are clear of allsurrounding structures and remain so whenresiliently mounted equipment movesthrough its maximum excursion undershock.

4. Locate flexible connection as close aspossible to the sound-mounted unit.

5. Support the free elbow of the configurationwith an approved pipe hanger so as not tosag or otherwise unduly stress or distort theconfiguration.

6. Do not appreciably change the alignmentof the hose configuration between theunpressurized and pressurized conditions.If you do, you could cause misalignmentor improper support at the fixed end.

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7. Obtain metal hose assembly identificationtags (fig. 6-38) from your local SIMA andsecure them onto one of the legs of the hoseconfiguration. The tag is made of a non-corroding material. Do not remove or alterthe tag once it is attached.

8. Leave the configuration in a conditionwhere one end can hang down unsupportedduring installation or dismantling ofpiping. Otherwise, you can damage thehose wire reinforcement.

Periodic Inspection ByShip’s Force

No less than once a quarter, preferably aboutonce a month, visually inspect all flexible pipingconnections to determine whether any signs ofweakness or unusual conditions exist. Inspect thehose in other systems semiannually. To assist youwhen performing this inspection, you shouldcompile a checkoff list of hose assemblies andlocations for your assigned spaces or equipment.This list will consist of all flexible devices installed(and their locations) together with a list ofinspections to be performed on each flexibledevice. When you perform the listed inspections,note the following:

1. Evidence of leakage at fitting ends.2. Discoloration of fittings (possible indica-

tion wire reinforcement is rusting).3. Slippage of hose out of fitting.4. Twisting of hose or other distortion or

unusual appearance.5. Cracking of outer rubber cover.6. Rubber cover rubbed thin by abrasion or

chafing.7. High pulsations, fluid hammer, or

whipping caused by pressure pulsations.8. Large vibrations due to improper supports

at the fixed end.9. Large area of hose covered with paint.

(The intent of this requirement is toeliminate having the flexible hose con-nections deliberately painted. The hosedoes not have to be replaced if a few paintdrops inadvertently fall onto it. Do notattempt to clean off dried paint from thehose.)

10. Check hangers to ensure they have notbroken off, distorted, or otherwisedamaged.

11. Soft spots or bulges on hose body(indicates weakening of bond between

12.

13.

14.

outer rubber cover and wire braid ordeterioration of the reinforcing wire).If results of visual inspection indicatesweakening of hose or fittings, or makeshose configuration suspect, replace thehose immediately, if at all possible. Keepunder surveillance while under pressureuntil it is replaced.If necessary to remove a flexible hoseconfiguration from the system, examinethe interior of the hose for cracks or othersigns of deterioration of the inner liner.Do not damage the liner by trying todislodge sea growth. Do not remove theend fittings from any section of hosewhich is to be installed.Presence of identification tag.

Storage

The following guidelines are recommended forproper storage of hose and fittings:

Hose-Hose should be stored in a dark,dry atmosphere away from electricalequipment; temperature should not exceed125°F. Storage in straight lengths ispreferred, but if hose is to be coiled, takecare to ensure the diameter of the bend isnot less than 3 feet. To prevent damageduring storage, wrap the hose with burlapor other suitable material.

Reusable End Fittings-Protect all threadswith tape or other suitable material, andwrap the entire fitting in a protectivecovering to prevent nicking or otherdamage.

Shelf Life

The following are shelf life requirements forhose and reusable end fittings:

Hose-Do not install reinforced rubberhose that is over 4 years old from the dateof manufacture. This time is measuredfrom the quarter and year of manufacturebut does not include the quarter year ofmanufacture. Consider the shelf life ofhose ended upon installation aboard ship.To ensure against its accidental use,dispose of any hose not installed that hasexceeded the above shelf life.

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Reusable End Fittings-There is noshelf life for end fittings. They shouldbe replaced on an individual basiswhen examination makes them suspect.

Servicing

No servicing or maintenance is required sincehose or fittings must be replaced at the slightestsuspicion of potential failure. If a fitting isremoved from a section of hose, that hosesection must not be reused, regardless of itsservice life.

Service Life of Rubber Hose

All rubber hose has a periodic replacementtime. All flexible rubber hose connections will bereplaced every 5 years (± 6 months) in criticalsystems and every 12 years in noncritical systems.Wire braided Teflon® hose has no specifiedshelf or service life. Its replacement is based oninspection of the hose for excessive wear ordamage.

FITTINGS

Some type of connector must be provided toattach the pipe, tube, or hose to the othercomponents of the system and to connect sectionsof the line to each other. There are many differenttypes of connectors (commonly called fittings)provided for this purpose. Some of the mostcommon types of fittings are covered in thefollowing paragraphs.

Threaded Joints

The threaded joints are the simplest type ofpipe fittings. Threaded fittings are not widely usedaboard modern ships except in low-pressure waterpiping systems. The pipe ends connected to theunion are threaded, silver-brazed, or weldedinto the tail pieces (union halves); then the twoends are joined by setting up (engaging andtightening up on) the union ring. The male andfemale connecting ends of the tail pieces arecarefully ground to make a tight metal-to-metalfit with each other. Welding or silver-brazing theends to the tail pieces prevents contact of thecarried fluid or gas with the union threading.

Figure 6-38.—Hose assembly identification tags.

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Bolted Flange Joints

Bolted flange joints (fig. 6-39) are suitable forall pressures now in use. The flanges are attachedto the piping by welding, brazing, screw threads(for some low-pressure piping), or rolling andbending into recesses. Those shown in figure 6-39are the most common types of flange jointsused. Flange joints are manufactured for allstandard fitting shapes, such as the tee, cross,elbow, and return bend. The Van Stone and thewelded-neck flange joints are used extensivelywhere piping is subjected to high pressures andheavy expansion strains. The design of the VanStone flange makes it easier to line up thefastening holes in the two parts of the flange.

Welded Joints

The majority of joints found in subassembliesof piping systems are welded joints, especiallyin high-pressure piping. The welding is doneaccording to standard specifications which definethe material and techniques. Three general classesof welded joints are fillet-weld, butt-weld, andsocket-weld (fig. 6-40).

Silver-Brazed Joints

Silver-brazed joints (fig. 6-41) are commonlyused for joining nonferrous piping when thepressure and temperature in the lines make theiruse practicable-temperatures must not exceed425 °F; for cold lines, pressure must not exceed3000 psi. The alloy is melted by heating the joint

Figure 6-39.—Four types of bolted flange piping joints.

with an oxyacetylene torch. This causes the moltenmetal to fill the few thousandths of an inchannular space between the pipe and the fitting.

Unions

The union fittings are provided in pipingsystems to allow the piping to be taken down forrepairs and alterations. Unions are available inmany different materials and designs to withstanda wide range of pressures and temperatures.Figure 6-42 shows some commonly used types ofunions/threaded pipe connectors. The union ismost commonly used for joining piping up to 2inches in size.

Flared Fittings

Flared fittings are commonly used in tubinglines. These fittings provide safe, strong,dependable connections without the necessity ofthreading, welding, or soldering the tubing. Flaredfittings are made of steel, aluminum alloy, or

Figure 6-40.—Various types of welded joints.

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Figure 6-41.—Silver-brazed joints.

bronze. Do not mix materials when using thesefittings. For example, for steel tubing use onlysteel fittings and for copper or brass tubing useonly bronze fittings. Figure 6-43 shows the mostcommon types of flared fittings.

Figure 6-42.—Unions/threaded pipe connectors.

Figure 6-43.—Flared-tube fittings.

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Flareless Fittings

Flareless fittings (figs. 6-44 and 6-45) aresuitable for use in hydraulic service and airservice systems at a maximum operating pressureof 3000 psi and a maximum operating temperatureof 250°F. Flareless fittings are installed toconserve space and to reduce weight, installationtime, and system cleaning time. Do not useflareless fittings if you do not have enough spaceto properly tighten the nuts or if you have toremove the equipment or piping for access to thefittings. An exception to this rule is a gauge board.It is designed so it may be removed as a unit forrepairs or alterations. Do not use flareless fittingswhere you cannot easily deflect the piping topermit assembly and disassembly.

Before assembly, ensure the tubing end issquare, concentric, and free of burrs. For aneffective fitting, be sure the cutting edge of thesleeve or ferrule bites into the periphery of thetube; you can do this by presetting the ferrule.

FLANGE SAFETY SHIELDS

A fuel fire in the MER or an AMR can becaused by a leak at a fuel oil or lube oil pipe flangeconnection. Even the smallest leak can spray finedroplets of oil on nearby hot surfaces. To reducethis possibility, FLANGE SAFETY SHIELDS areprovided around piping flanges of inflammableliquid systems, especially in areas where the firehazard is apparent. The spray shields are usuallymade of aluminized glass cloth and are simplywrapped and wired around the flange.

PIPE HANGERS

Pipe hangers and supports are designed andlocated to support the combined weight of the

Figure 6-44.—Double-male flareless fitting.

Figure 6-45.—Typical flareless fitting.

piping, fluid, and insulation. They absorb themovements imposed by thermal expansion of thepipe and the motion of the ship. The pipe hangersand supports prevent excessive vibration of thepiping and resilient mounts or other materials.They are used in the hanger arrangement to breakall metal-to-metal contact to lessen unwantedsound transmissions.

One type of pipe hanger you need to becomefamiliar with is the variable spring hanger. Thisis used to support the ship’s bleed air piping. Itprovides support by directly compressing a springor springs. The loads carried by the hangers areequalized by adjustment of the hangers when theyare hot. These hangers have load scales attachedto them with a traveling arm or pointer that movesin a slot alongside the scale. This shows the degreeof pipe movement from cold to hot. The cold andhot positions are marked on the load scale. Youshould check the hangers when they are hot toensure that the pointers line up with the hotposition on the load scales. You can adjusthangers that are out of position by loosening thejam nut on the hanger rod and turning theadjusting bolt of the hanger.

INSPECTIONS AND MAINTENANCE

Reasonable care must be given to the variouspiping assemblies as well as to the units connectedto the piping systems. Unless the piping systemis in good condition, the connected units ofmachinery cannot operate efficiently and safely.You should be familiar with all the recommendedmaintenance procedures and observe the safetyprecautions when working on piping systems.

The most important factor in maintainingpiping systems in satisfactory condition is keepingjoints, valves, and fittings tight. To ensure thiscondition, you need to make frequent tests andinspections.

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Piping should be tested at the frequency andtest pressure specified following the PMS and theapplicable equipment technical manual. Testpressure must be maintained long enough to showany leaks or other defects in the system.

Instruction manuals should be available andfollowed for the inspection and maintenance ofpiping systems and associated equipment;however, if the manufacturer’s instruction manualis not available, you should refer to Naval Ships’Technical Manual, chapter 505, for details ofpiping inspection and maintenance.

PIPING SYSTEMIDENTIFICATION MARKING

All piping should be marked to show the nameof the service, destination (where possible), anddirection of flow (fig. 6-46).

The name of the service and destination shouldbe painted on by stencil or hand lettering, or byapplication of previously printed, stenciled, orlettered adhesive-backed tape. Lettering will be1 inch high for a 2-inch or larger outside diameterbare pipe or insulation, For smaller sizes,lettering size may be reduced or label platesattached by wire or other suitable means.

Direction of flow will be indicated by anarrow 3 inches long pointing away from thelettering. For reversible flow, arrows are to beshown on each end of the lettering.

Black is used for lettering and arrows.However, on dark-colored pipe (including oxygenpiping), white is used.

Markings will be applied to piping inconspicuous locations, preferably near thecontrol valves and at suitable intervals so everyline will have at least one identification markingin each compartment through which it passes.Piping in cabins and officers’ wardrooms will notnormally be marked.

Figure 6-46.—Pipe markings.

PACKING ANDGASKET MATERIAL

Packing and gasket materials are required toseal joints in steam, water, gas, air, oil, and otherlines and to seal connections that slide or rotateunder normal operating conditions. There aremany types and forms of packing and gasketmaterials available commercially.

PACKING AND GASKET SELECTION

To simplify the selection of packing and gasketmaterials commonly used in naval service, theNaval Sea Systems Command has prepared apacking and gasket chart, Mechanical StandardDrawing B-153 (see fig. 6-47 at the end ofthis chapter). It shows the symbol numbers andthe recommended applications for all types andkinds of packing and gasket materials.

The symbol number used to identify each typeof packing and gasket has a four-digit number.(See List of Materials in fig. 6-47.) The first digitshows the class of service with respect to fixed andmoving joints; the numeral 1 shows a moving joint(moving rods, shafts, valve stems), and thenumeral 2 shows a fixed joint (flanges, bonnets).The second digit shows the material of which thepacking or gasket is primarily composed—asbestos, vegetable fibre, rubber, metal, and soforth. The third and fourth digits show thedifferent styles or forms of the packing or gasketmade from the material.

Practically all shipboard packing and gasketproblems can be solved by selection of thecorrect material from the listings on the packingand gasket chart. The following examples showthe kind of information that you can get from thepacking and gasket chart.

Suppose you are required to repack andinstall a valve in a 150-psi seawater service system.Refer to figure 6-47, the packing and gasket chart.Under the subhead Symbols and Specificationsfor Equipments, Piping and Independent Systems,you find that symbol 1103 indicates a suitablematerial for repacking the valve. Notice that thefirst digit is numeral 1, indicating that the materialis for use in a moving joint. Under the List ofMaterials, you find the packing is asbestos rod,braided.

For installing the valve, you need propergaskets. By use of the same subhead, you find thatsymbols 2150, 215l type II, 2152, and 2290 typeII are all suitable for installing the valve. Noticethat the first digit is numeral 2, which indicatesthat it is designed for fixed joints. Again, by

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referring to the List of Materials, you can deter-mine the composition of the gasket.

Besides the Naval Ship Systems Commanddrawing, most ships have a packing and gasketchart made up specifically for each ship. The ship-board chart shows the symbol numbers and thesizes of packing and gaskets required in the ship’spiping system, machinery, and hull fittings.

PACKING OF MOVING JOINTS

Valves are components used to control thetransfer of liquids and gases through fluid

piping systems. Most valves have moving jointsbetween the valve stem and the bonnet. Whenfluid is on one or both sides of a moving joint,the joint may leak. Sealing the joint prevents thisleakage. Sealing a moving joint presents aproblem because the seal must be tight enoughto prevent leakage, yet loose enough to let thevalve stem turn without binding. Packing is themost common method of sealing a moving joint.

Packing is a sealing method that usesbulk material (packing) that is reshaped bycompression to effectively seal a moving joint.

Figure 6-48.—Types of packing.

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Figure 6-48 shows several types of packing incommon use today.

Packing is inserted in STUFFING BOXESthat have annular chambers located aroundvalve stems and rotating shafts. The packingmaterial is compressed to the necessary extent

Figure 6-49.—Corrugated ribbon packing.

and held in place by gland nuts or otherdevices.

A corrugated ribbon packing has beendeveloped for universal use on valves. Thispacking comes in four widths (1 inch, 3/4 inch,l/2 inch, and l/4 inch) and is easily cut to length,rolled on the valve stem, and pushed into thestuffing box to form a solid, endless packing ringwhen compressed (fig. 6-49). Corrugated ribbonpacking is suitable for use in systems of hightemperatures (up to 1200°F and 2000 psi). It iseasily removed since it does not harden.

PACKING OF FIXED JOINTS

Figure 6-50 shows gasket material used forfixed joints. At one time, fiied joints could besatisfactorily sealed with gaskets of compressedasbestos sheet packing (view A of fig. 6-50).Today the 15 percent rubber content of the

Figure 6-50.—.Fixed-joint gaskets. A. Sheet asbestos gaskets. B. Serrated-face metal gaskets. C. Spiral-wound, metallic-asbestos gaskets.

6-35

packing makes it unsatisfactory for modem, high-temperature, high-pressure equipment. Two typesof gaskets (metallic or semimetallic) are in use inpresent day high-temperature and high-pressureinstallations. Gaskets of corrugated copper or ofasbestos and copper are sometimes used on low-and medium-pressure lines.

Serrated-face metal gaskets (view B of fig.6-50) made of steel, Monel, or soft iron haveraised serrations to make a better seal at thepiping flange joints. These gaskets have resiliency.Line pressure forces the serrated faces tighteragainst the adjoining flange. The gaskets shownare of two variations.

Spiral-wound, metallic-asbestos gaskets (viewC of fig. 6-50) are made of interlocked strandsof preformed corrugated metal and asbestosstrips, spirally wound together (normally calledthe FILLER), and a solid metal outer or centeringring (normally called the RETAINING RING).

Figure 6-51.—O-ring seal with two cross-sectional views.

The centering ring is used as a reinforcement toprevent blowouts. The filler piece is replaceable.When renewing a gasket, you should remove thispiece from the retaining metal ring and replaceit with a new filler. Do not discard the solid metalretaining outer or centering ring unless it isdamaged. You can compress the gaskets to thethickness of the outer or centering ring.

When renewing a gasket in a flange joint, youmust exercise special precautions when breakingthe joint, particularly in steam and hot water lines,or in saltwater lines that have a possibility of directconnection with the sea. Be sure to observe thefollowing precautions:

1.2.

3.4.

5.

6.

No pressure is on the line.The line pressure valves, including thebypass valves, are firmly secured, wiredclosed, and tagged.The line is completely drained.At least two flange-securing bolts and nutsdiametrically opposite remain in placeuntil the others are removed, thenslackened to allow breaking of the joint,and removed after the line is clear.Precautions are taken to prevent explosionsor fire when breaking joints of flammableliquid lines.Proper ventilation is ensured before jointsare broken in closed compartments.

These precautions may prevent seriousexplosions, severe scalding of personnel, orflooding of compartments. You shouldthoroughly clean all sealing and bearing surfacesfor the gasket replacement. Check the gasket seatswith a surface plate, and scrape as necessary. Thisaffords uniform contact. Replace all damagedbolt studs and nuts. In flange joints with raisedfaces, the edges of gaskets may extend beyond theedge of the raised face.

O-RINGS

Another method of preventing leakage in fluidsystems is by use of O-ring seals. Figure 6-51shows an O-ring seal with two cross-sectionalviews. An O-ring is a doughnut-shaped, circularseal (view A of fig. 6-5 1) that is usually a moldedrubber compound. An O-ring seal has an O-ringmounted in a groove or cavity (usually called agland).

When the gland is assembled (view B of fig.6-51), the O-ring cross section is compressed.When installed, the compression of the O-ring

6-36

cross section enables it to seal low fluid pressures.The greater the compression, the greater is thefluid pressure that can be sealed by the O-ring.The pressure of the O-ring against the gland wallsequals the pressure caused by the recovery forceof the compressed O-ring plus the fluid pressure.

The fluid pressure against the walls of thegland and the stiffness of the O-ring prevent fluidfrom leaking past the O-ring. If the downstreamclearance is large, the O-ring is forced into thisclearance (view C of fig. 6-51). The stiffness ofthe O-ring material prevents the O-ring frombeing forced completely through the downstreamclearance unless that clearance is abnormally largeor the pressure is excessive.

O-rings are commonly used for sealing becauseof their simplicity, ruggedness, low cost, ease ofinstallation, ease of maintenance, and theireffectiveness over wide pressure and temperatureranges.

Failure of an O-ring can sometimes begin withthe removal of an old O-ring. If you incorrectlyremove an O-ring with pointed or sharp tools, youcan scratch or dent critical surface finishes thatcan result in seal failure.

Before installing a new O-ring, inspect the seal-ing surfaces for any abrasions and wipe them freeof any dust, dirt, or other contaminants. Beforeinstallation, inspect the O-ring for any damage.If faulty, discard it.

When you install the O-ring, lubricate it. Inmost cases it is already coated with the systemfluid or petrolatum grease. Do not stretch theO-ring more than twice its original size duringinstallation, and do not roll or twist it into place.This may leave a permanent twist in the O-ringand reduce its effectiveness and shorten its life.

When installing an O-ring, take extreme careto avoid forcing it over sharp edges, corners, andthreaded sections. You should use some type ofsleeve or cover to avoid damaging the O-ring.

FASTENERS

The proper use of fasteners is very importantand cannot be overemphasized. Many shipboardmachinery casualties have resulted from fastenersthat were not properly installed. Machinery vibra-tion, thermal expansion, and thermal contractionwill loosen the fasteners. At sea, loosening effectsare increased by the pitch and roll of the ship. Youare familiar with such standard fasteners as nuts,bolts, washers, wingnuts, and screws. In chapter3 we discussed how nuts and bolts (threaded

fasteners) are torqued to the manufacturer’sspecifications and the lockwire method ofensuring that certain types of fasteners will notcome loose. In this section of chapter 6 we willdiscuss some of the new developments in fastenertechnology, such as the various types of locknuts,which you may not be familiar with.

THREADED LOCKING DEVICES

An important part of fastener technology hasincluded the development of several methods forlocking mated threads of fasteners. Many of thelatest methods include the locking device ormethod as an integral part of the fastenerassembly and are referred to as self-locking nutsor bolts. Self-locking fasteners are more expensivethan some older methods but compare favorablyin cost with pin or wiring methods.

Length of Protrusion

Male threads on threaded fasteners, wheninstalled and tightened, will protrude the distanceof at least one thread length beyond the top ofthe nut or plastic locking ring. Excessiveprotrusion is a hazard, particularly wherenecessary clearances, accessibility, and safety areimportant. Where practicable, the number ofthreads protruding should not exceed five. In nocase should thread protrusion exceed 10 threadsunless specifically approved by the work super-visor. (This is the one-to-ten rule.)

Where screw threads are used for setting oradjusting (such as valve stem packing glands andtravel stops) or where installed threaded fastenersdo not strictly follow the one-to-ten rule but havegiven satisfactory service, the rule does notapply. An example of an acceptable existinginstallation would be where a male thread is flushwith the top of a nut or where more than 10threads protruding is of no foreseeableconsequence.

Repair of Damaged Threads

You can remedy damaged external threads byreplacing the fastener. In large equipment castingsyou must repair damaged internal threads to savethe part. You can repair internal threads by redrill-ing the damaged thread; clean and either installa solid wall insert or tap for a helical coil insert.These inserts, in effect, return the tapped hole toits original size so it takes the original matingfastener.

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LOCKNUTS

Locknuts are used in special applicationswhere you want to ensure that the componentsjoined by the fasteners will not loosen. Two typesof locknuts are in common use. The first typeapplies pressure to the bolt thread and can beused where frequent removal may be required.The second type deforms the bolt thread and isused only where frequent removal is unnecessary.The first type includes plastic ring nuts, nyloninsert nuts, jam nuts, spring nuts, and springbeam nuts. The second type includes distortedcollar nuts and distorted thread nuts; they are notcommonly found in gas turbine equipment andwill not be covered in this section.

Plastic Ring Nuts

Plastic ring nuts (fig. 6-52) deform the plasticinsert when they are installed. The resilient plasticmaterial is forced to assume the shape of themating threads, creating large frictional forces.

Nylon Insert Nuts

Nylon insert nuts have plastic inserts (plugs)that do not extend completely around the threads.

They force the nut to the side, cocking it slightly.This produces frictional forces on one side of thebolt thread. Although the plastic insert lockswithout seating, proper torque applied to the nutstretches the bolt, creating clamping forces thatadd to the locking abilities of the nut. Beforereusing nylon insert nuts (fig. 6-53), check theinserts. If worn or torn, discard the nut. Installthe nut (on clean lightly lubricated threads) fingertight. If you can install the nut to the point wherethe bolt threads pass the insert without a wrench,discard the nut and use a new one.

Jam Nuts

You should install jam nuts (fig. 6-54) withthe thinner nut to the working surface and thethicker nut to the outside. The thin nut isdeformed by the wider nut and pressed againstthe working surface and threads.

Spring Nuts

Spring nuts (fig. 6-55) lock by the side gripon the bolt. When tightened, the spring nut

Figure 6-52.—Plastic ring nut.

Figure 6-53.—Nylon insert nut.

Figure 6-54.—Jam nuts.

Figure 6-55.—Spring nuts.

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flattens, or straightens, a spring section. Manytypes of spring nuts use curved metal springs,bellows, and coil springs. All spin on and offwithout locking until the pressure against theworking surface straightens the spring.

You should always consult equipmentmanuals for the proper torque value. Be surethreads are always clean and lightly lubricatedwith the proper lubrication. Discard any withdamaged threads.

Spring Beam Nuts

Spring beam nuts (fig. 6-56) are formed witha light taper in the threads toward the upperportion of the nut. Slots are cut in the outerportion, forming segments that can be forced out-ward when the nut is installed. Elastic reactioncauses the segments to push inward, gripping thebolt. Like the nylon insert nut, this nut does notdeform the bolt threads and can be used onfrequently removed items. If you can thread thenut past the deflection segments without a wrench,discard the nut and replace it with a new one.

LOCKWASHERS

Many installations on board naval ships stilluse lockwashers to prevent threaded fastenersfrom loosening. If loosening has not been aproblem, you may replace worn lockwashers withan identical type; however, if loosening has beena problem, you should use self-locking fastenersinstead of lockwashers.

The most common lockwasher used is thehelical spring washer. Other types are the conicaland toothed tab.

Helical Spring Lockwashers

The helical spring lockwasher (split ring)(fig. 6-57) is flattened when the bolt is torqued

Figure 6-56.—Spring beam nuts.

Figure 6-57.—Helical spring lockwasher.

down. When torqued, it acts as a flat washercontributing normal friction for locking the screwor bolt and the working surface; it also maintainsthe tension on the bolt. Because of the helicalspring lockwasher’s small diameter, it is usuallynot used on soft materials or with oversized orelongated holes.

Curved or Conical Spring Lockwashers

Curved or conical spring lockwashers havealmost the same properties as the helical springlockwasher. They provide a constant tension onthe bolt or screw when loosened. The tensionproduced is usually less than that produced by thehelical spring lockwasher. Like any locking devicerelying on tension, spring lockwashers may loosenon shock loading. When the bolt stretches morethan the spring distortion from the shock loading,the washer serves no further purpose. Recheck thewasher, where possible, when shock is sufficientto suspect loosening. Some spring lockwashershave teeth on the outer edge. These teeth do notaid in locking, but they prevent side slippage andturning.

Toothed Lockwashers

Toothed lockwashers (fig. 6-58) have teeth thatare twisted or bent to prevent loosening. Cutting

Figure 6-58.—Toothed lockwashers.

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edges engage both working surfaces on the nutand bolt or screw. Some have teeth on the innerdiameter for applications where teeth projectingbeyond the nut are not desired. The most commontype have teeth on the outer diameter. Washerswith teeth on both inside and outside diametersare used for soft materials and oversize holes. Theteeth are twisted, so as the nut is installed andtorqued down, the rim of the washer supports thepressure. Any backing off of the nut or boltreleases tension that allows the teeth to dig intothe working surfaces of the nut and bolt.

INSULATION

The purpose of insulation is to retard thetransfer of heat FROM piping that is hotter thanthe surrounding atmosphere or TO piping thatis cooler than the surrounding atmosphere.Insulation helps to maintain the desiredtemperatures in all systems. In addition, itprevents sweating of piping that carries cool orcold fluids. Insulation also serves to protectpersonnel from being burned by coming incontact with hot surfaces. Piping insulationrepresents the composite piping covering whichconsists of the insulating material, lagging, andfastening. The INSULATING MATERIALoffers resistance to the flow of heat; theLAGGING, usually of painted canvas, is theprotective and confining covering placed over theinsulating materials; and the FASTENINGattaches the insulating material to the piping andto the lagging.

Insulation covers a wide range of tempera-tures, from the extremely low temperatures of therefrigerating plants to the very high temperaturesof the ship’s waste heat boilers. No one materialcould possibly be used to meet all the conditionswith the same efficiency.

INSULATION MATERIALS

The following QUALITY REQUIREMENTSfor the various insulating materials are takeninto consideration by the Navy in the stan-dardization of these materials:

1. Low heat conductivity2. Noncombustibility3. Lightweight4. Easy molding and installation capability5. Moisture repellant

6.

7.

8.

9.10.

Noncorrosive, insoluble, and chemicallyinactiveComposition, structure, and insulatingproperties unchanged by temperatures atwhich it is to be usedOnce installed, should not cluster, becomelumpy, disintegrate, or build up in massesfrom vibrationVerminproofHygienically safe to handle

Insulating material is available in preformedpipe coverings, blocks, batts, blankets, and felts.Refer to Naval Ships’ Technical Manual, Chapter635, “Thermal, Fire, and Acoustic Insulation,”for detailed information on insulating materials,their application, and safety precautions.

The insulating cements are comprised of avariety of materials, differing widely amongthemselves as to heat conductivity, weight, andother physical characteristics. Typical of thesevariations are the asbestos substitute cements,diatomaceous cements, and mineral and slag woolcements. These cements are less efficient thanother high-temperature insulating materials, butthey are valuable for patchwork emergency repairsand for covering small irregular surfaces (valves,flanges, joints, and so forth). Additionally, thecements are used for a surface finish over blockor sheet forms of insulation, to seal jointsbetween the blocks, and to provide a smoothfinish over which asbestos substitute or glass clothlagging may be applied.

REMOVABLE INSULATION

Removable insulation will be found on thebleed air systems and waste heat boiler systems.Removable insulation is also installed in thefollowing locations:

Flange pipe joints adjacent to machineryor equipment that must be broken whenunits are opened for inspection or overhaul

Valve bonnets of valves larger than2 inches internal pipe size (IPS) thatoperate at 300 psi and above or at 240°Fand above

All pressure-reducing and pressure-regulating valves, pump pressure gov-ernors, and strainer bonnets

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GENERAL INSULATIONPRECAUTIONS

You should observe the following generalprecautions relative to the application andmaintenance of insulation:

1. Fill and seal all air pockets and cracks.Failure to do this will cause large losses inthe effectiveness of the insulation.

2. Seal the ends of the insulation and taperoff to a smooth, airtight joint. At jointends or other points where insulation isliable to be damaged, use sheet metallagging over the insulation. You shouldcuff flanges and joints with 6-inch lagging.

3. Keep moisture out of all insulation work.Moisture is an enemy of heat insulation justas much as it is in electrical insulation. Anydampness increases the conductivity of allheat-insulating materials.

4. Insulate all hangers and other supports attheir point of contact from the pipe orother unit they are supporting; otherwise,a considerable quantity of heat will be lostvia conduction through the support.

5. Keep sheet metal covering bright andunpainted unless the protective surface hasbeen damaged or has worn off. Theradiation from bright-bodied and light-colored objects is considerably less thanfrom rough and dark-colored objects.

6. Once installed, heat insulation requirescareful inspection, upkeep, and repair.Replace lagging and insulation removed tomake repairs as carefully as when originallyinstalled. When replacing insulation, makecertain that the replacement material is ofthe same type as had been used originally.

7. Insulate all flanges with easily removableforms. These forms are made up as padsof insulating material, wired or bound inplace, and the whole covered with sheetmetal casings, which are in halves.

8. Asbestos Control: Inhalation of excessivequantities of asbestos fibre or filler canproduce severe lung damage in the form ofdisabling or fatal fibrosis of the lungs.Asbestos has also been found to be a casualfactor in the development of cancer of themembrane lining the chest and abdomen.Lung damage and disease usually developslowly and often do not become apparentuntil years after the initial exposure. If yourplans include a long and healthy Navyretirement, you have no business doingasbestos lagging rip-out without propertraining, protective clothing, and super-vision. Most systems of today’s modernNavy have been purged of asbestos and anasbestos substitute material installed in itsplace. Some of the older class vessels maystill have some asbestos insulation installed.Use caution when handling lagging andinsulation from these vessels. If in doubt,contact your supervisor and request themedical department conduct a survey of thematerial in question.

SUMMARY

In this chapter we have described some ofthe basic types of piping system componentsyou find aboard ship. Aboard ship you willfind a variety of pipes, tubing, and hoseassemblies that have many uses in the engineeringplant. To perform maintenance and repair onpiping systems, you must familiarize yourself withthe manufacturers’ technical manuals, the ship’sengineering operational sequencing system, theappropriate Naval Ships’ Technical Manual, andthe PMS for the individual system. The informa-tion in this chapter is intended to provide you withthe basic knowledge of piping systems and howthey are constructed. For more indepth informa-tion on piping systems and their components,refer to NSTM, chapter 505.

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Figure 6-47.—Application criteria for packings and gaskets.

6-42

Figure 6-47.—Application criteria for packings and gaskets—Continued.

6-43

CHAPTER 7

ENGINEERING SUPPORTAND AUXILIARY EQUIPMENT

Gas turbine propulsion plants are dependenton reliable auxiliary systems. The propermaintenance and operation of auxiliary systemswill enhance the performance of main propulsionmachinery. As a GSE or GSM, you must havea thorough knowledge of main propulsionauxiliary machinery and systems. In this chapterwe will describe some of the maintenance,operating problems, and repair of pumps,purifiers, air compressors, dehydrators, waste-heat boilers, and oily-water separators.

Before any maintenance or repair work isstarted, you should consult the MRCs and themanufacturers’ technical manuals. Thesematerials contain information concerningspecifications, clearances, procedural steps, andtroubleshooting techniques of engine-roomauxiliary machinery.

Proper maintenance or repair work consistsof problem diagnosis, disassembly, measure-ments, corrections of problems, and reassembly.Use of proper tools, knowledge of the construc-tion of equipment, proper work-site management,and cleanliness are keys to successful maintenanceand repair work.

Good housekeeping is an integral part ofpreventive maintenance. Nothing adds more tothe impression of a well-maintained plant thancleanliness. Team work is required on the part ofall hands to maintain a clean plant. Maintenancepersonnel must realize that the repair job is NOTcomplete until the old and surplus material hasbeen removed. It is difficult for operatorsto remain concerned about cleanliness whenimproperly designed or maintained equipmentcontinually allows oil or water to leak. If a pieceof equipment is designed to leak a fluid, be surethe leakoff remains within specifications.

Work-site cleanliness is as important asspace cleanliness. Dirt and foreign matter

7-1

are s harmful to machinery as improperlubrication.

Early replacement and/or failure resultsfrom inadequate attention to detail duringmaintenance procedures. Improper materials,wrong clearances, misalignments, or inatten-tion to torque specifications are but a fewof the commonly overlooked maintenancerequirements. Memory should not be reliedupon to determine when an inspection shouldbe made, bearings lubricated, or equipmentrotated. Sooner or later something will beneglected and failure will result, posinga safety problem for personnel and equip-ment.

With the knowledge gained in this chapter,you should be able to describe pumps, purifiers,air compressors, dehydrators, waste-heat boilers,and oily-water separators in terms of theirconstruction, function, and operation. Thematerial presented in this chapter is representativein nature. By studying this material, you shouldbe able to relate to the specific equipment foundon your ship.

PUMPS

Pumps are vitally important to the operationof your ship. If they fail, the power plant theyserve also fails. In an emergency, pump failurescan prove disastrous. Therefore, maintainingpumps in an efficient working order is a veryimportant task of the Gas Turbine SystemsTechnician.

It is not practical or necessary to mentionall of the various locations where pumps arefound aboard ship. You will learn theirlocation and operation as you perform yourduties as a GSE or a GSM. Pumps with

which you are primarily concerned are usedfor such purposes as

providing fuel oil to the GTE,

circulating lubricating (lube) oil to thebearings and gears of the MRG,

supplying seawater for the coolers inengineering spaces,

pumping out the bilges, and

transferring fuel oil to various storage andservice tanks.

CIASSIFICATION OF PUMPS

Pumps aboard ship outnumber all otherauxiliary machinery units. They include such typesas centrifugal, rotary, and jet pumps. In thefollowing section we discuss these different pumpsand their application to the engineering plant.

Centrifugal Pumps

Aboard gas turbine ships, centrifugal pumpsof various sizes are driven by electric motors tomove different types of liquid. The fire pump andseawater service pump are two examples of thistype of pump.

A basic centrifugal pump has an impellerkeyed to a drive shaft, which is rotated by anelectric motor. The drive shaft is fitted inside acasing which has a suction inlet and a dischargeour let. Figure 7-1 shows the arrangement ofcomponents in a centrifugal pump.

CENTRIFUGAL PUMP CLASSIFICA-TION.—Centrifugal pumps may be classsified inseveral ways. For example, they maybe eithersingle-stage or multistage. A single-stage pumphas only one impeller; a multistage pump has twoor more impellers housed together in one casing.In a multistage pump, each impeller usually actsseparately, discharging to the suction of the next-stage impeller. Centrifugal pumps are alsoclassified as horizontal or vertical, depending onthe position of the pump shaft.

Impellers used in centrifugal pumps may beclassified as single-suction or double-suction,depending on the way in which liquid enters theeye of the impeller. Figure 7-2 shows single-suction and double-suction arrangements ofcentrifugal pump impellers. The single-suctionimpeller (view A) allows liquid to enter theeye from one side only; the double-suctionimpeller (view B) allows liquid to enter theeye from both sides. The double-suction arrange-ment has the advantage of balancing the endthrust in one direction with the end thrust in theother direction.

Impellers are also classified as CLOSED orOPEN. A closed impeller has side walls thatextend from the eye to the outer edge of the vanetips; an open impeller does not have side walls.Most centrifugal pumps used in the Navy haveclosed impellers.

CONSTRUCTION—As a rule, the casing forthe liquid end of a pump with a single-suctionimpeller is made with an end plate that can beremoved for inspection and repair of the pump.A pump with a double-suction impeller isgenerallv made so one-half of the casing may belifted without disturbing the pump.

Figure 7-1.—Centrifugal pump

7-2

Figure 7-2.—Centrifugal pump impellers. A. Single-suction. B. Double-suction.

Since an impeller rotates at high speed, it mustbe carefully machined to minimize friction. Animpeller must be balanced to avoid vibration. Aclose radial clearance must be maintained betweenthe outer hub of the impeller and that part of thepump casing in which the hub rotates. The pur-pose of this is to minimize leakage from the dis-charge side of the pump casing to the suction side.

Because of the high rotational speed of theimpeller and the necessarily close clearance, therubbing surfaces of both the impeller hub and thecasing at that point are subject to stress, causingrapid wear. To eliminate the need for replacingan entire impeller and pump casing solely becauseof wear in this location, most centrifugal pumpsare designed with replaceable casing wearing rings.

In most centrifugal pumps, the shaft is fittedwith a replaceable sleeve. The advantage ofusing a sleeve is that it can be replaced moreeconomically than the entire shaft.

Mechanical seals and stuffing boxes are usedto seal between the shaft and the casing. Mostpumps are now furnished with mechanical seals;mechanical seals do not result in better pumpoperation but do provide a better environment,dry bilges, and preservation of the liquid beingpumped.

Seal piping (liquid seal) is installed to cool themechanical seal. Most pumps in saltwater servicewith total head of 30 psi or more are also fittedwith cyclone separators. These separators usecentrifugal force to prevent abrasive material(such as sand in the seawater) from passingbetween the sealing surfaces of the mechanicalseal. There is an opening at each end of theseparator. The opening at the top is for “clean”water, which is directed though tubing to themechanical seals in the pump. The high-velocity“dirty” water is directed through the bottom ofthe separator, back to the inlet piping for thepump.

Bearings support the weight of the impellerand shaft and maintain the position of theimpeller-both radially and axially. Some bear-ings are grease-lubricated with grease cups toallow for periodic relubrication.

The power end of the centrifugal pump hasan electric motor that is maintained by you or theship’s Electrician’s Mate.

OPERATION.—Liquid enters the rotatingimpeller on the suction side of the casing andenters the eye of the impeller (fig. 7-3). Liquid

7-3

Figure 7-3.—Centrifugal pump flow.

is thrown out through the opening around theedge of the impeller and against the side of thecasing by centrifugal force. Centrifugal force isforce that is exerted upon a body or substance byrotation. Centrifugal force impels the body orsubstance outward from the axis of rotation.When liquid is thrown out to the edge ofthe casing, a region of low pressure (belowatmospheric) is created around the center of theimpeller; more liquid moves into the eye to replacethe liquid that was thrown out. Liquid movesinto the center of the impeller with a high velocity(speed). Therefore, liquid in the center of theimpeller has a low pressure, but it is moving ata high velocity.

Liquid moving between the blades of theimpeller spreads out, which causes the liquid toslow down. (Its velocity decreases.) At the sametime, as the liquid moves closer to the edge of thecasing, the pressure of the liquid increases. Thischange (from low pressure and high velocity atthe center to high pressure and low velocity at theedge) is caused by the shape of the openingbetween the impeller blades. This space has theshape of a diffuser, a device that causes thevelocity-pressure relationship of any fluid thatmoves through it to change.

A centrifugal pump is considered to be anonpositive-displacement pump because thevolume of liquid discharged from the pumpchanges whenever the pressure head changes. Thepressure head is the combined effect of liquidweight, fluid friction, and obstruction to flow. Ina centrifugal pump, the force of the dischargepressure of the pump must be able to overcomethe force of the pressure head; otherwise, thepump could not deliver any liquid to a pipingsystem. The pressure head and the dischargepressure of a centrifugal pump oppose each other.When the pressure head increases, the dischargepressure of the pump must also increase. Sinceno energy can be lost, when the discharge pressureof the pump increases, the velocity of flow mustdecrease. On the other hand, when the pressurehead decreases, the volume of liquid dischargedfrom the pump increases. As a general rule, acentrifugal pump is usually located below theliquid being pumped. (NOTE: This discussionassumes a constant impeller speed.)

Figure 7-4 shows that when the pumpdischarge is blocked, nothing happens because theimpeller is hollow. A tremendous buildup in

7-4

Figure 7-4.—Nonpositive-displacement pump.

pressure cannot occur because the passages in theimpeller (between the discharge and suction sideof the pump) act like a built-in relief valve. Whenthe discharge pressure and pressure head are equal(as in this case), the impeller is allowed to rotate(slips) through the liquid in the casing.

NOTE: Centrifugal pumps used for inter-mittent service may have to run for long periodsof time against a blocked discharge. Frictionbetween the impeller and the liquid raises thetemperature of the liquid in the casing and causesthe pump to overheat. To prevent this, a smallline is connected between the discharge and thesuction piping of the pump.

When a centrifugal pump is started, the ventline must be opened to release entrained air. Theopen passage through the impeller of a centrifugalpump also causes another problem. It is possiblefor liquid to flow backwards (reverse flow)through the pump. A reverse flow, from thedischarge back to the suction, can happen whenthe pressure head overcomes the dischargepressure of the pump. A reverse flow can alsooccur when the pump is not running and anotherpump is delivering liquid to the same pipingsystem. To prevent a reverse flow of liquidthrough a centrifugal pump, a check valve isusually installed in the discharge line.

NOTE: Instead of two separate valves, someinstallations use a globe stop-check valve.

With a check valve in the discharge line,whenever the pressure above the disk rises abovethe pressure below it, the check valve shuts. Thisprevents liquid from flowing backwards throughthe pump.

MAINTENANCE.—You must observe theoperation and safety precautions pertaining topumps by following the EOP subsystem of theEOSS—if your ship has EOSS. If not, use NavalShips’ Technical Manual and/or the instructionsposted on or near each individual pump. Youmust follow the manufacturer’s technical manualor MRCs for PMS-related work for allmaintenance work. The MRCs list in detail whatyou have to do for each individual maintenancerequirement.

Mechanical Seals .—Mechanical seals arerapidly replacing conventional packing as themeans of controlling leakage on centrifugalpumps. Pumps fitted with mechanical sealseliminate the problem of excessive stuffing boxleakage, which can result in pump and motorbearing failures and motor winding failures.

Where mechanical shaft seals are used, thedesign ensures that positive liquid pressure issupplied to the seal faces under all conditions ofoperation and that there is adequate circulationof the liquid at the seal faces to minimize thedeposit of foreign matter on the seal parts.

One type of a mechanical seal is shown infigure 7-5. Spring pressure keeps the rotating sealface snug against the stationary seal face. Therotating seal and all of the assembly below it areaffixed to the pump shaft. The stationary seal faceis held stationary by the seal gland and packingring. A static seal is formed between the two sealfaces and the sleeve. System pressure within thepump assists the spring in keeping the rotating sealface tight against the stationary seal face. The typeof material used for the seal face depends on theservice of the pump. When a seal wears out, itis simply replaced.

You should observe the following precautionswhen performing maintenance on mechanicalseals:

Do not touch new seals on the sealing facebecause body acid and grease can cause theseal face to prematurely pit and fail.

Figure 7-5.—Type-1 mechanical seal.

Replace mechanical seals when the seal isremoved for any reason or when theleakage rate cannot be tolerated.

Position mechanical shaft seals on theshaft by stub or step sleeves. Shaft sleevesare chamfered (beveled) on outboard endsto provide ease of mechanical sealmounting.

Do not position mechanical shaft seals byusing setscrews.

Fire pumps and all seawater pumps installedin surface ships are being provided withmechanical shaft seals with cyclone separators.The glands are designed to incorporate two ormore rings of packing if the mechanical shaft sealfails.

A water flinger is fitted on the shaftoutboard of the stuffing box glands to preventleakage from the stuffing box following alongthe shaft and entering the bearing housings.They must fit tightly on the shaft. If theflingers are fitted on the shaft sleeves insteadof on the shaft, ensure that no water leaks underthe sleeves.

Stuffing Box Packing. —Although most cen-trifugal pumps on gas turbine ships havemechanical seals, you should be familiar withstuffing box packing.

7-5

The packing in centrifugal pump stuffingboxes (fig. 7-6) is renewed following the PMS.When replacing packing, be sure to use packingof the specified material and the correct size.Stagger the joints in the packing rings so they fallat different points around the shaft. Pack thestuffing box loosely and set up lightly on thegland, allowing a liberal leakage. With the pumpin operation, tighten the glands and graduallycompress the packing. It is important to do thisgradually and evenly to avoid excessive friction.Uneven tightening could cause overheating andpossible scoring of the shaft or the shaft sleeve.

On some centrifugal pumps, a lantern ring isinserted between the rings of the packing. Whenrepacking stuffing boxes on such pumps, be sureto replace the packing beyond the lantern ring.The packing should not block off the liquid sealline connection to the lantern ring after the glandhas been tightened.

Figure 7-6 shows how the packing is arranged.Notice how the lantern ring lines up with theliquid seal connection when the gland is tightened.

Renewing Shaft Sleeves.—In some pumps theshaft sleeve is pressed onto the shaft tightly bya hydraulic press. In this case, the old sleeve mustbe machined off with a lathe before a new one

can be installed. On others, the shaft sleeve mayhave a snug slip-on fit, butted up against ashoulder on the shaft and held securely in placewith a nut. On smaller pumps, you can install newsleeves by removing the water end casing,impeller, and old shaft sleeves. New sleeves arecarried as repair parts; they can also be made inthe machine shop. On a large pump, the sleeveis usually pressed on; the old sleeve must bemachined off before a new one can be pressed on.You must disassemble the pump and take thesleeve to a machine shop, a repair shop, or a navalshipyard to have this done.

To prevent water leakage between the shaftand the sleeve, some sleeves are packed, othershave an O-ring between the shaft and theabutting shoulder. For detailed information,consult the appropriate manufacturer’s technicalmanual or applicable blueprint.

Renewing Wearing Rings.—The clearancebetween the impeller and the casing wearing ring(fig. 7-7) must be maintained as directed by themanufacturer. When clearances exceed thespecified amount, the casing wearing ringmust be replaced. On most ships, this jobcan be done by the ship’s force, but it requiresthe complete disassembly of the pump. All

Figure 7-6.—Stuffing box on a centrifugal pump.

7-6

necessary information on disassembly of the unit,dimensions of the wearing rings, and reassemblyof the pump is specified by PMS or can be foundin the manufacturer’s technical manual. Failureto replace the casing wearing ring when theallowable clearance is exceeded results in adecrease of pump capacity and efficiency. If youhave to disassemble a pump because of someinternal trouble, check the wearing ring forclearance. Measure the outside diameter of theimpeller hub with an outside micrometer and theinside diameter of the casing wearing ring with aninside micrometer; the difference between the twodiameters is the actual wearing ring diametricclearance. By checking the actual wearing ringclearance with the maximum allowable clearance,you can decide whether to renew the ring beforereassembling the pump. The applicable MRCs area readily available source of information onproper clearances.

Wearing rings for most small pumps arecarried aboard ship as part of the ship’s repairparts allowance. These may need only a slightamount of machining before they can be installed.For some pumps, spare rotors are carried aboardship. The new rotor can be installed and the oldrotor sent to a repair activity for overhaul.Overhauling a rotor includes renewing the wearingrings, bearings, and shaft sleeve.

Operating Troubles.—You will be responsiblefor the maintenance of centrifugal pumps. The

Figure 7-7.—Impeller, impeller wearing ring, and casingwearing ring for a centrifugal pump.

following table is a description of some of theproblems you will have to deal with together withthe probable causes:

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Insufficient suction pressure may cause vibration,as well as noisy operation and fluctuatingdischarge pressure.

Rotary Pumps

Another type of pump you find aboard shipis the rotary pump. A number of types are

included in this classification, among which arethe gear pump, the screw pump, and the movingvane pump. Unlike the centrifugal pump, whichwe have discussed, the rotary pump is a positive-displacement pump. This means that for eachrevolution of the pump, a fixed volume of fluidis moved regardless of the resistance against whichthe pump is pushing. As you can see, any blockagein the system could quickly cause damage to thepump or a rupture of the system. You, as thepump operator, must always be sure the systemis properly aligned so a complete flow pathexists for fluid flow. Also, because of theirpositive displacement feature, rotary pumpsrequire a relief valve to protect the pump andpiping system. The relief valve lifts at a presetpressure and returns the system liquid either tothe suction side of the pump or back to the supplytank or sump.

Rotary pumps also differ from centrifugalpumps in that they are essentially self-priming.As we saw in our discussion of centrifugal pumps,the pump is usually located below the liquid beingpumped; gravity creates a static pressure headwhich keeps the pump primed. A rotary pump canoperate within limits with the pump located abovethe liquid being pumped.

A good example of the principle that makesrotary pumps self-priming is the simple drinking

Figure 7-8.—Gear pump located above the tank.

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straw. As you suck on the straw, you lower theair pressure inside the straw. Atmosphericpressure on the surface of the liquid surroundingthe straw is therefore greater and forcesthe liquid up the straw. The same conditionsbasically exist for the gear and screw pumpto prime itself. Figure 7-8 shows a gearpump located above the tank. The tankmust be vented to allow air into the tankto provide atmospheric pressure on the sur-face of the liquid. To lower the pressureon the suction side of the pump, the clear-ances between the pump parts must be closeenough to pump air. When the pump starts,the air is pumped through the dischargeside of the pump and creates the low-pres-sure area on the suction side which allowsthe atmospheric pressure to force the liquidup the pipe to the pump. To operate properly,the piping leading to the pump must haveno leaks or it will draw in air and canlose its prime.

Rotary pumps are useful for pumping oil andother heavy viscous liquids. In the engine room,rotary pumps are used for handling lube oil andfuel oil and are suitable for handling liquids overa wide range of viscosities.

Rotary pumps are designed with verysmall clearances between rotating parts andstationary parts to minimize leakage (slippage)from the discharge side back to the suctionside. Rotary pumps are designed to operateat relatively slow speeds to maintain theseclearances; operation at higher speeds causeserosion and excessive wear, which result inincreased clearances with a subsequent decreasein pumping capacity.

Figure 7-9.—Simple gear pump.

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Classification of rotary pumps is generallybased on the types of rotating element. In thefollowing paragraphs, the main features of somecommon types of rotary pumps are described.

GEAR PUMPS.—The simple gear pump(fig. 7-9) has two spur gears that meshtogether and revolve in opposite directions. Oneis the driving gear, and the other is thedriven gear. Clearances between the gear teeth(outside diameter of gear) and the casing andbetween the end face and the casing are only afew thousandths of an inch. As the gears turn,the gears unmesh and liquid flows into the pocketsthat are vacated by the meshing gear teeth. Thiscreates the suction that draws the liquid into thepump. The liquid is then carried along in thepockets formed by the gear teeth and the casing.On the discharge side, the liquid is displaced bythe meshing of the gears and forced out throughthe discharge side of the pump.

One example of the use of a gear pump is inthe LM2500 engine fuel pump. However, gearpumps are not used extensively on gas turbineships.

SCREW PUMPS.—Several different typesof screw pumps exist. The differences be-tween the various types are the number ofintermeshing screws and the pitch of the screws.Figure 7-10 shows a double-screw, low-pitch

Figure 7-10.—Double-screw, low-pitch pump.

pump; and figure 7-11 shows a triple-screw, high-pitch pump. Screw pumps are used aboard shipto pump fuel and lube oil and to supply pressureto the hydraulic system. In the double-screwpump, one rotor is driven by the drive shaft andthe other by a set of timing gears. In the triple-screw pump, a central rotor meshes with two idlerrotors.

In the screw pump, liquid is trapped andforced through the pump by the action of rotatingscrews. As the rotor turns, the liquid flows in be-tween the threads at the outer end of each pairof screws. The threads carry the liquid alongwithin the housing to the center of the pump,where it is discharged.

Most screw pumps are now equipped withmechanical seals. If the mechanical seal fails, thestuffing box has the capability of accepting tworings of conventional packing for emergency use.

SLIDING VANE PUMPS.—The sliding-vanepump (fig. 7-12) has a cylindrically boredhousing with a suction inlet on one side and adischarge outlet on the other side. A rotor (smallerin diameter than the cylinder) is driven about anaxis that is so placed above the center line of thecylinder as to provide minimum clearance betweenthe rotor and cylinder at the top and maximumclearance at the bottom.

Figure 7-11.—Triple-screw, high-pitch pump.

Figure 7-12.—Sliding vane pump.

The rotor carries vanes (which move in andout as the rotor rotates) to maintain sealed spacesbetween the rotor and the cylinder wall. The vanestrap liquid on the suction side and carry it to thedischarge side, where contraction of the spaceexpels liquid through the discharge line. The vanesslide on slots in the rotor. Vane pumps are usedfor lube oil service and transfer, tank stripping,bilge, aircraft fueling and defueling, and, ingeneral, for handling lighter viscous liquids.

Jet Pumps

The pumps discussed so far in this chapterhave had a variety of moving parts. One type ofpump you find in the engine room is the jet pump,usually called an eductor. Figure 7-13 shows aneductor, which has no moving parts. These pumpsare used for pumping large quantities of wateroverboard in such applications as pumping bilgesand dewatering compartments. Eductors are alsobeing used on distilling plants as air or brineeductors.

Eductors use a high-velocity jet of seawaterto lower the pressure in the chamber around theconverging nozzle. Seawater is supplied to theconverging nozzle at a relatively low velocity andexits the nozzle at a high velocity. As the seawaterleaves the nozzle and passes through the chamber,air becomes entrained in the jet stream and ispumped out of the chamber. Pressure in thechamber decreases, allowing atmospheric pressureto push the surrounding water into the chamberand mix with the jet stream. The divergingnozzle allows the velocity of the fluid to decreaseand the pressure to increase; the dischargepressure is then established.

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Figure 7-13.—Eductor.

Figure 7-14 is an example of a typical ship-board eductor system. Note that the eductordischarge piping is below the water line. Theswing-check valve above the overboard-dischargevalve prevents water from backing up into thesystem if the system pressure drops below the out-side water pressure. To prevent engineering spacesfrom flooding, you must follow the step-by-stepprocedures that are posted next to eductorstations.

ALIGNMENT OF SHAFTAND COUPLING

When you install or assemble pumps drivenby electric motors, ensure that the unit is alignedproperly. If the shaft is misaligned, you mustrealign the unit to prevent shaft breakage anddamage to bearings, pump casing wearing rings,

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Figure 7-14.—Typical eductor system.

and throat bushings. Always check the shaft align-ment with all the piping in place.

Some driving units are connected to thepump by a FLEXIBLE COUPLING. A flexiblecoupling (fig. 7-15) is intended to take care ofonly a slight misalignment. Misalignment shouldnever exceed the amount specified by the pump

Figure 7-15.—Grid-type flexible coupling.

manufacturer. If the misalignment is excessive,the coupling parts are subjected to severe punish-ment, necessitating frequent replacement of pins,bushings, and bearings. It is absolutely necessaryto have the rotating shafts of the driving anddriven units in proper alignment. Figure 7-16shows coupling alignment.

You should check the shaft alignment whenthe pump is opened for repair or maintenance,or if a noticeable vibration occurs. You mustrealign the unit if the shafts are out of line orinclined at an angle to each other. Wheneverpracticable, check the alignment with all pipingin place and with the adjacent tanks and pipingfilled.

When the driving unit is connected to thepump by a FLANGE COUPLING, the shaftingmay require frequent realignment, which may beindicated by high temperatures, noises, and wornbearings or bushings.

Wedges, or shims, are sometimes placed underthe bases of both the driven and driving units (fig.7-16, view A) for ease in alignment when themachinery is installed. When the wedges or otherpacking have been adjusted so the outsidediameters and faces of the coupling flanges runtrue as they are manually revolved, the chocks are

fastened, the units are securely bolted to thefoundation, and the coupling flanges are boltedtogether.

The faces of the coupling flanges should bechecked at 90-degree intervals. This method isshown in figure 7-16, view B. Find the distancesbetween the faces at point a, point b (on theopposite side), point c, and point d (opposite pointc). This action will show whether the couplingfaces are parallel to each other. If they are notparallel to each other, adjust the driving unit orthe pump with shims until the couplings checktrue. While measuring the distances, you mustkeep the outside diameters of the coupling flangesin line. To do this, place the scale across the twoflanges, as shown in figure 7-16, view C. If theflanges do not line up, raise or lower one of theunits with shims, or shift them sideways.

The procedure for using a thickness gauge tocheck alignments is similar to that for a scale.When the outside diameters of the couplingflanges are not the same, use a scale on thesurface of the larger flange, and then use athickness gauge between the surface of the smallerflange and the edge of the scale. When thespace is narrow, check the distance between thecoupling flanges with a thickness gauge, as shown

Figure 7-16.—Coupling alignment.

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in figure 7-16, view D. Wider spaces are checkedwith a piece of square key stock and a thicknessgauge.

PURIFIERS

Detailed instructions are furnished with eachpurifier concerning its construction, operation,and maintenance. When you are responsible forthe operation and maintenance of a purifier, studythe appropriate manufacturer’s technical manualand follow the instructions carefully. In thefollowing section we will discuss general informa-tion on the methods of purification and theprinciples of operation of centrifugal purifiers.Centrifugal purifiers are used for purification ofboth lube oil and fuel. However, since theprinciples are the same for both, we will discusslube oil only.

A purifier may remove both water andsediment, or it may remove sediment only.When water is involved in the purificationprocess, the purifier is usually called aSEPARATOR. When the principal contaminantis dirt or sediment, the purifier is usedas a CLARIFIER. Purifiers are generally usedas separators for the purification of fuel.When used for purification of a lube oil, a purifiermay be used as either a separator or a clarifier.Whether a purifier is used as a separator or aclarifier depends on the water content of theoil that is being purified.

The following general information will helpyou understand the purification process, thepurposes and principles of purifier operation, andthe basic types of centrifugal purifiers in use innaval service.

PURIFIER OPERATION

In the purification of fluid, centrifugalforce is the fundamental principle of opera-tion. A centrifugal purifier is essentially acontainer that is rotated at high speed whilecontaminated lube oil is forced through, androtates with, the container. However, onlymaterials that are in the lube oil can beseparated by centrifugal force. For example,JP-5 or naval distillate cannot be separatedfrom lube oil, nor can salt be removed from

seawater by centrifugal force. Water, how-ever, can be separated from lube oil becausewater and lube oil are immiscible (incapableof being mixed). Furthermore, there mustbe a difference in the specific gravities ofthe materials before they can be separated bycentrifugal force.

When a mixture of lube oil, water, andsediment stands undisturbed, gravity tends toform an upper layer of lube oil, an intermediatelayer of water, and a lower layer of sediment.The layers form because of the specific gravitiesof the materials in the mixture. If the lubeoil, water, and sediment are placed in acontainer that is revolving rapidly around avertical axis, the effect of gravity is negligiblein comparison with that of the centrifugalforce. Since centrifugal force acts at rightangles to the axis of rotation of the container,the sediment with its greater specific gravityassumes the outermost position, forming alayer on the inner surface of the container.Water, being heavier than lube oil, forms anintermediate layer between the layer of sedimentand the lube oil, which forms the innermostlayer. The separated water is discharged aswaste, and the lube oil is discharged to thesump. The solids remain in the rotating unit.

Separation by centrifugal force is furtheraffected by the size of the particles, the viscosityof the fluids, and the time during which thematerials are subjected to the centrifugal force.In general, the greater the difference in specificgravity between the substances to be separated andthe lower the viscosity of the lube oil, the greaterwill be the rate of separation.

PURIFIER CLASSIFICATION

Two basic types of purifiers are used inNavy installations. Both types use centrifugalforce. Principal differences in these two machinesexist, however, in the design of the equip-ment and the operating speed of the rotatingelements. In one type, the rotating elementis a bowl-like container that encases a stackof discs. This is the disc-type DeLaval purifier,which has a bowl operating speed of about7,200 rpm. In the other type, the rotatingelement is a hollow cylinder. This machineis the tubular-type Sharples purifier, whichhas an operating speed of 15,000 rpm.

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Figure 7-17.—Disc-type centrifugal purifier.

Figure 7-18.—Parts of a disc-type purifier bowl.

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Figure 7-19.—Path of contaminated oil through a disc-type purifier bowl (DeLaval).

Disc-Type Purifier

Figure 7-17 shows a cutaway view of a disc-type centrifugal purifier. The bowl is mounted onthe upper end of the vertical bowl spindle, drivenby a worm wheel and friction clutch assembly.A radial thrust bearing at the lower end of thebowl spindle carries the weight of the bowl spindleand absorbs any thrust created by the drivingaction. Figure 7-18 shows the parts of a disc-typebowl. The flow of fluid through the bowl andadditional parts are shown in figure 7-19.Contaminated fluid enters the top of the revolvingbowl through the regulating tube. The fluid thenpasses down the inside of the tubular shaft, outthe bottom, and up into the stack of discs. As thedirty fluid flows up through the distribution holesin the discs, the high centrifugal force exerted bythe revolving bowl causes the dirt, sludge, andwater to move outward. The purified fluid is

forced inward and upward, discharging from theneck of the top disc. The water forms a sealbetween the top disc and the bowl top. (Thetop disc is the dividing line between thewater and the fluid.) The discs divide thespace within the bowl into many separate narrowpassages or spaces. The liquid confined withineach passage is restricted so it can flow only alongthat passage. This arrangement minimizes agita-tion of the liquid as it passes through the bowl.It also forms shallow settling distances betweenthe discs.

Any water, along with some dirt and sludge,separated from the fluid, is discharged throughthe discharge ring at the top of the bowl.However, most of the dirt and sludge remains inthe bowl and collects in a more or less uniformlayer on the inside vertical surface of the bowlshell.

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Tubular-Type Purifier

A cutaway view of a tubular-type centrifugalpurifier is shown in figure 7-20. This type ofpurifier consists of a bowl or hollow rotor that

rotates at high speeds. The bowl has an openingin the bottom to allow the dirty fluid to enter. Italso has two sets of openings at the top to allowthe fluid and water to discharge. The bowl of thepurifier is connected by a coupling unit to a

Figure 7-20.—Tubular-lype centrifugal purifier.

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spindle. The spindle is suspended from a ball bear-ing assembly. The bowl is belt-driven by anelectric motor mounted on the frame of thepurifier.

The lower end of the bowl extends into aflexibly mounted guide bushing. The assemblyrestrains movement of the bottom of the bowl,but it also allows the bowl enough movement tocenter itself during operation. Inside the bowl isa device with three flat plates that are equallyspaced radially. This device is commonly referredto as the THREE-WING DEVICE, or just thethree-wing. The three-wing rotates with the bowland forces the liquid in the bowl to rotateat the same speed as the bowl. The liquid to becentrifuged is fed, under pressure, into thebottom of the bowl through the feed nozzle.

After the bowl has been primed with water,separation is basically the same as it is in the disc-type purifier. Centrifugal force causes clean fluidto assume the innermost position (lowest specificgravity), and the higher density water and dirt areforced outward towards the sides of the bowl.Fluid and water are discharged from separateopenings at the top of the bowl. Any solidcontamination separated from the liquid remainsinside the bowl all around the inner surface.

GENERAL NOTES ON PURIFIEROPERATIONS

For maximum efficiency, purifiers should beoperated at the maximum designed speed andrated capacity. Since reduction gear oils areusually contaminated with water condensation,the purifier bowls should be operated asseparators and not as clarifiers.

When a purifier is operated as a separator,PRIMING OF THE BOWL with fresh water isessential before any oil is admitted into thepurifier. The water serves to seal the bowl andto create an initial equilibrium of liquid layers.If the bowl is not primed, the oil will be lostthrough the water discharge port.

Several factors influence purifier operation.The time required for purification and the out-put of a purifier depend on such factors as theviscosity of the oil, the pressure applied to the oil,the size of the sediment particles, the differencein the specific gravity of the oil, the substancesthat contaminate the oil, and the tendency of theoil to emulsify.

The viscosity of the oil will determine thelength of time required to purify the oil. The moreviscous the oil, the longer the time will be to purify

it to a given degree of purity. Decreasing theviscosity of the oil by heating is one of the mosteffective methods of facilitating purification.

Even though certain oils may be satisfactorilypurified at operating temperatures, a greaterdegree of purification will generally result byheating the oil to a higher temperature. Toaccomplish this, the oil is passed through a heater,where the proper temperature is obtained beforethe oil enters the purifier bowl.

Oils used in naval ships may be heated tospecified temperatures without adverse effects,but prolonged heating at higher temperaturesis not recommended because of the tendencyof such oils to oxidize. Oxidation resultsin rapid deterioration. In general, oil shouldbe heated sufficiently to produce a viscosity ofapproximately 90 seconds Saybolt universal(90 SSU).

Pressure should NEVER be increased abovenormal to force a high-viscosity oil through thepurifier. Instead, viscosity should be decreased byheating the oil. The use of excess pressure to forceoil through the purifier will result in less efficientpurification. On the other hand, a reduction inthe pressure that the oil is forced into the purifierwill increase the length of time the oil is underthe influence of centrifugal force and will resultin improved purification.

The proper size discharge ring (ring dam) mustbe used to ensure the oil discharged from apurifier is free of water, dirt, and sludge. The sizeof the discharge ring used depends on the specificgravity of the oil being purified. All dischargerings have the same outside diameter, but haveinside diameters of different sizes.

You should obtain specific details of operatinga given purifier from the appropriate instructionsprovided with the unit. The information you havebeen provided is general and applicable to bothtypes of purifiers.

AIR COMPRESSORS

The air compressor is the heart of anycompressed air system. It takes in atmos-pheric air, compresses it to the pressuredesired, and moves it into supply lines orinto storage tanks for later use. Air compressorscome in different designs and configurationsand have different methods of compression.Some of the most common types used ongas turbine ships will be discussed in thischapter.

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Before describing the various types of aircompressors found on gas turbine ships, we willdiscuss the composition of air and some of thethings air may contain. This discussion shouldhelp you understand why air compressors havespecial features that prevent water, dirt, and oilvapor from getting into compressed air pipingsystems.

Air is composed mainly of nitrogen andoxygen. At atmospheric pressure (within the rangeof temperatures for the earth’s atmosphere), airis in a gaseous form. The earth’s atmosphere alsocontains varying amounts of water. Dependingon weather conditions, water will appear in avariety of forms, such as rain (liquid water), snowcrystals, ice (solid water), and vapor. Vapor iscomposed of tiny drops of water that are lightenough to stay airborne. Clouds are an exampleof water vapor.

Since air is a gas, it will expand when it isheated. Consequently, the heating of air will causea given amount of air to expand, take up morespace (volume), and hold more water vapor.When a given amount of air at a given temper-ature and pressure is no longer able to soak upwater vapor, the air is saturated, and thehumidity is 100 percent.

When air cools, its density increases; however,its volume and ability to hold water decrease.When temperature and pressure conditions causeair to cool and to reach the dew point, any watervapor in the air will condense into a liquid state(water). In other words, one method of drying airout is to cool it until it reaches the dew point.

Besides nitrogen, oxygen, and water vapor, aircontains particles of dust and dirt that are so tinyand lightweight that they remain suspended in theair. You may wonder how the composition of airdirectly affects the work of an air compressor.Although one cubic foot of air will not hold atremendous amount of water or dirt, you shouldrealize that air compressors have capacities thatare rated in hundreds of standard cubic feet perminute (cfm). This is a very high rate of flow.When a high flow rate of dirty, moisture-ladenair is allowed to enter and pass through an aircompressor, the result is rapid wear of the sealsand load-bearing parts, internal corrosion (rust),and early failure of the unit. The reliability anduseful life of any air compressor is extended bythe installation of filters. Filters will remove mostof the dirt and dust from the air before it entersthe equipment. On the other hand, most of thewater vapor in the air at the intake will passdirectly through the filter material and will be

compressed with the air. When air is compressed,it becomes very hot. As we mentioned earlier, hotair is capable of holding great amounts of water.The water is removed as the compressed air isrouted through coolers. The coolers remove theheat from the airstream and cause some of thewater vapor to condense into liquid (condensate).The condensate must be periodically drained fromthe compressor.

Although the coolers will remove some of thewater from the air, simple cooling between thestages of compression (intercooling) and coolingof the airstream after it leaves the compressor(aftercooling) will not make the air dry. Whenclean dry air suitable for pneumatic control andother shipboard systems is required, air from thecompressor is routed through air-drying units.Many air-drying units are capable of removingenough water vapor from the airstream to causethe dew point to be as low as – 60°F. Some ofthe more common devices used to remove watervapor from the airstream, such as dehydrators,will be explained later in this chapter.

CLASSIFICATION OFAIR COMPRESSORS

An air compressor may be classified accordingto pressure (low, medium, or high), type ofcompressing element, and whether the dischargedair is oil-free.

Because of our increasing need for oil-free airaboard ship, the oil-free air compressor isgradually replacing most of the standard low-pressure and high-pressure air compressors. Forthis reason, we will focus most of our discussionon the features of oil-free air compressors.

According to the Naval Ships’ TechnicalManual, chapter 55 1, compressors are classifiedas low, medium, or high pressure. Low-pressureair compressors (LPACs) have a dischargepressure of 150 psi or less. Medium-pressurecompressors have a discharge pressure of 151 psito 1,000 psi. Compressors that have a dischargepressure above 1,000 psi are classified as high-pressure air compressors (HPACs).

Low-Pressure or Ship’sService Air Compressors

Only two types of LPACs are used on gasturbine ships, the screw type and the reciprocatingtype.

SCREW TYPE.—The helical-screw type ofcompressor is a relatively new design of oil-free air

7-18

compressor. It is being installed aboard some ofour newer ships, such as the FFG-7 class ships.This low-pressure air compressor is a single-stagepositive-displacement, axial-flow, helical-screwtype of compressor. It is often referred to as a

screw-type compressor. Figure 7-21 shows thegeneral arrangement of the LPAC unit.

Compression is caused by the meshing of twohelical rotors (a male and a female rotor, as shownin fig. 7-22) located on parallel shafts and enclosed

Figure 7-21.—LPAC (screw type).

Figure 7-22.—LPAC, compressor section.

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in a casing. Air inlet and outlet ports are locatedon opposite sides of the casing. Atmospheric airis drawn into the compressor through the filter-silencer. The air passes through the air cylinder-operated unloader (butterfly) valve and into theinlet part of the compressor when the valve is inthe open (load) position. Fresh water is injectedinto the airstream as it passes through the inletport of the compressor casing.

The injected fresh water serves two purposes:(1) it reduces the air discharge temperature causedby compression, and (2) it seals the runningclearances to minimize air leakage. Most of theinjected water is entrained into the airstream asit moves through the compressor.

The compression cycle starts as the rotorsunmesh at the inlet port. As rotation continues,air is drawn into the cavity between the male rotorlobes and into the grooves of the female rotor.The air is trapped in these grooves, or pockets,and follows the rotative direction of each rotor.As soon as the inlet port is closed, the compression

cycle begins as the air is directed to the opposite(discharge) end of the compressor. The rotorsmesh, and the normal free volume is reduced. Thereduction in volume (compression) continues, witha resulting increase in pressure, until the closingpocket reaches the discharge port.

The entrained water is removed from thedischarged air by a combined separator and waterholding tank. The water in the tank passesthrough a seawater-cooled heat exchanger. Thecooled water then recirculates to the compressorfor reinjection.

During rotation and throughout the meshingcycle, the timing gears maintain the correctclearances between the rotors. Since no contactoccurs between the rotor lobes and grooves,between the rotor lobes and casing, or betweenthe rotor faces and end walls, no internal oillubrication is required. This design allows thecompressor to discharge oil-free air.

For gear and bearing lubrication, lube oil froma force-feed system is supplied to each end of the

Figure 7-23.—LPAC (reciprocating type).

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compressor. Mechanical seals serve to keep theoil isolated from the compression chamber.

RECIPROCATING TYPE.—All recipro-cating air compressors are similar to each otherin design and operation. The following discussiondescribes the basic components and principles ofoperation of a low-pressure reciprocating aircompressor.

The LPAC is a vertical, two-stage, single-acting compressor that is belt-driven by anelectrical motor. Two first-stage cylinders and one

second-stage cylinder are arranged in-line in in-dividual blocks mounted to the crankcase (frame)with a distance piece (frame extension). Thecrankcase is mounted on a subbase that supportsthe motor, moisture separators, and a rackassembly. The intercooler, aftercooler, freshwaterheat exchanger, and freshwater pump aremounted on the rack assembly. The subbase servesas the oil sump. Figure 7-23 shows the general ar-rangement of the reciprocating-type compressor.

The compressor is of the crosshead design.Figure 7-24 shows cross-sectional views of

Figure 7-24.—L.PAC, cross-sectional views (reciprocating type).

7-21

the LPAC. The frame extension houses thecrossheads and crosshead guides and is open tothe atmosphere. It separates the cylinders, whichare not oil lubricated, from the crankcase. Oilwiper assemblies (seals) are located in the frameextension to scrape lubricating oil off the pistonrods when the compressor is in operation. Oildeflector plates are attached to the piston rods toprevent any oil that creeps through the scrapersfrom entering the cylinders. Oil that is scrapedfrom the piston rods drains back to the sump. Airleakage along the piston rods is prevented by fullfloating packing assemblies bolted to the under-side of the cylinder blocks.

During operation, ambient air is drawn intothe first-stage cylinders through the inlet filtersilencers and inlet valves during the downstroke.When the piston reaches the bottom of its stroke,the inlet valve closes and traps the air in thecylinder. When the piston moves upward, thetrapped air is compressed and forced out of thefirst-stage cylinders, through the first-stage coolerand the first-stage moisture separator. When the

second-stage piston starts its downstroke, the airis drawn into the second-stage cylinder. Then itis further compressed, followed by a cooling andmoisture removal process similar to the first stage.

High-Pressure Air Compressors

The HPAC is a vertical, five-stage, recipro-cating air compressor. It is driven by being directlyconnected to an electric motor. Refer to figures7-25 and 7-26 as we describe the compressor.

The subbase supports the compressor assem-bly, the electric drive motor, and the coolers andrack assembly. The crankcase is bolted directlyto the subbase and is made up of the frame andframe extension. The frame houses the crankshaftand oil pump. The frame extension is open to theatmosphere and isolates the conventionallylubricated frame from the oil-free cylinders. Thecrosshead guides are machined in the frameextension. A uniblock casting contains the firstthree-stage cylinders and is mounted on the frameextension (fig. 7-26). The cylinders are arranged

Figure 7-25.—HPAC.

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Figure 7-26.—HPAC, cross-sectional views.

in line. The first stage is in the center, the second During operation, ambient air is drawnstage is at the motor end, and the third stage is into the first-stage cylinder through the in-outboard. The fourth stage is mounted above the let filter and inlet valves. The first stagesecond stage, and the fifth stage is above the third is double acting, and air is drawn into thestage. The fourth- and fifth-stage pistons are lower cylinder area as the piston is movingtandem mounted to the second- and third-stage upward. At the same time, air in the upperpistons, respectively. cylinder is being compressed and forced out

7-23

the upper discharge valve. As the pistonmoves downward, air is drawn into the uppercylinder; likewise, air in the lower cylinderis being compressed and forced out the lowerdischarge valve. Compressed air leaves the first-stage discharge valves and flows through the first-stage intercooler, and into the first-stage moistureseparator.

The first-stage separator has a small tankmounted on the side of the compressor framebelow the gauge panel and has a holding tankmounted below the cooler rack. The separatorsfor the remaining stages handle smaller volumesof air due to compression, and as a result theseparators and holding chambers are smaller andare integrated into one tank. Condensate isremoved from the air as it collides with theinternal tank baffles and collects in the holdingchamber.

Air from the first-stage separator is drawn intothe single-acting, second-stage cylinder on theupward stroke of the piston. As the piston travelsdownward, the air is compressed and forced outthe discharge valve. The second-stage dischargeair passes through the second-stage intercoolerinto the second separator.

The third stage draws air from the secondseparator and compresses it in the same manneras in the second stage. Third-stage air enters apulsation bottle before passing through the thirdinterstage cooler. Pulsation bottles are used afterthe third and fifth compression stages to minimizethe shock effect of inlet and discharge pulses aswell as pressure changes due to condensatedraining.

After passing through the third interstagecooler and moisture separator, the air isdrawn into the fourth-stage cylinder on thedownstroke of the piston. As the pistontravels upward, the air is compressed andforced out the discharge valve. Then it passesthrough the fourth-stage intercooler and moistureseparator.

Air is drawn into the fifth-stage cylinder onthe piston downstroke and is compressed anddischarged on the upstroke. The discharge airpasses through the fifth-stage pulsation bottle, theaftercooler, the moisture separator, a back-pressure valve, and a check valve before enteringthe ship’s HP piping.

MAINTENANCE OFAIR COMPRESSORS

As a GSE or a GSM, you must be thoroughlyfamiliar with the operational and safetyprocedures for operating or maintaining anair compressor. Always use the correct EOPwhen operating an air compressor. Beforestarting any maintenance or repair work,you should consult the MRCs and the manu-facturers’ technical manuals. These materials con-tain information concerning specifications,clearances, procedural steps, and troubleshoot-ing techniques. Compressed air is potentiallyvery dangerous. Remember that cleanlinessis of greatest importance in all maintenancethat requires the opening of compressed airsystems.

SAFETY PRECAUTIONS

Many hazards are associated with pres-surized air, particularly air under high pres-sure. Dangerous explosions have occurred inhigh-pressure air systems because of DIESELEFFECT. If a portion of an unpressurizedsystem or component is suddenly and rapidlypressurized with high-pressure air, a largeamount of heat is produced. If the heat isexcessive, the air may reach the ignitiontemperature of the impurities (oil, dust, andso forth) present in the air and piping.When the ignition temperature is reached,a violent explosion will occur as these impuritiesignite. Ignition temperatures may also result fromother causes, such as rapid pressurization of a low-pressure, dead-end portion of the piping system,malfunctioning of compressor aftercoolers, andleaky or dirty valves.

Air compressor accidents have also beencaused by improper maintenance procedures.These accidents can happen when you disconnectparts under pressure, replace parts with unitsdesigned for lower pressures, and install stopvalves or check valves in improper locations.Improper operating procedures have resulted inair compressor accidents with serious injury topersonnel and damage to equipment.

You must take every possible step to minimizethe hazards inherent in the process of compres-sion and in the use of compressed air. Strictlyfollow all safety precautions outlined in the

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manufacturers’ technical manuals and in theNaval Ships’ Technical Manual, chapter 551.Some of these hazards and precautions are asfollows:

1. Explosions can be caused by dust-laden airor by oil vapor in the compressor or receiver ifabnormally high temperatures exist. Leaky ordirty valves, excessive pressurization rates, orfaulty cooling systems may cause these hightemperatures.

2. NEVER use distillate fuel or gasoline as adegreaser to clean compressor intake filters,cylinders, or air passages. These oils vaporizeeasily and will form a highly explosive mixturewith the air under compression.

3. Secure a compressor immediately if youobserve that the temperature of the air beingdischarged from any stage exceeds the maximumtemperature specified.

4. NEVER leave the compressor station afterstarting the compressor unless you are sure thatthe control and unloading devices are operatingproperly.

5. Before working on a compressor, besure the compressor is secured and cannotstart automatically or accidentally. Completelyblow down the compressor, and then secureall valves (including the control or unload-ing valves) between the compressor and thereceiver. Follow the appropriate tag-out pro-cedures for the compressor control valvesand the isolation valves. When the gaugesare in place, leave the pressure gauge cut-out valves open at all times.

6. Before disconnecting any part of anair system, be sure the part is not underpressure. Always leave the pressure gauge cut-out valves open to the sections to which they areattached.

7. Avoid rapid operation of manual valves.The heat of compression caused by a sudden flowof high pressure into an empty line or vessel cancause an explosion if oil or other impurities arepresent. Slowly crack open the valves until flowis noted, and keep the valves in this positionuntil pressure on both sides has equalized.Keep the rate of pressure rise under 200 psi persecond.

DEHYDRATORS

The removal of moisture from compressed airis an important feature of compressed air systems.Some moisture is removed by the intercoolers andaftercoolers, as explained earlier in this chapter.Air flasks and receivers are provided with low-point drains so any collected moisture may drainperiodically. However, many shipboard uses forcompressed air require air with an even smallermoisture content than is obtained through thesemethods. Water vapor in air lines can create otherproblems that are potentially hazardous, such asthe freezing of valves and controls. Theseconditions can occur when air at very highpressure is throttled to a low-pressure area at ahigh flow rate. The venturi effect of the throttledair produces very low temperatures, which willcause any moisture in the air to freeze into ice.Under these conditions, a valve (especially anautomatic valve) may become very difficult orimpossible to operate. Also, moisture in any airsystem can cause serious water hammering (abanging sound) within the system. For thesereasons, air dehydrators or dryers are used toremove most of the water vapor from compressedair.

The Navy uses two basic types of airdehydrators and a combination of the two. Theseair dehydrators are classified as follows:

Type I—Refrigeration

Type II—Heater, desiccant

Type III—Refrigeration, desiccant

Each of these types is designed to meet therequirements specified for the quality of thecompressed air to be used in pneumatic controlsystems or for clean, dry air used for shipboardelectronic systems. Specific requirements usuallyinvolve operating pressure, flow rate, dew point,and purity (percentage of aerosols and size ofparticles). We will briefly discuss each of the typesof air dehydrators.

REFRIGERATION AIR DEHYDRATOR(TYPE I)

Refrigeration is one method of removingmoisture from compressed air. The dehydrator

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in figure 7-27 is a REFRIGERATION DE-HYDRATOR or REFRIGERATED AIRDRYER. This unit removes water vapor entrainedin the stream of compressed air by causing thewater to condense into a liquid that is heavier thanair. Air flowing from the separator/holding tankfirst passes through the air-to-air heat exchanger,where some of the heat of compression is removedfrom the airstream. The air then moves throughthe evaporator section of the dehydrator, wherethe air is chilled by circulating refrigerant. In thisunit, the airstream is cooled to a temperature thatis below the dew point. This will cause the watervapor in the air to condense so it can be removedby the condensate drain system. After leaving theevaporator section, the dehydrated air movesupward through the cold air side of the air-to-airheat exchanger. In the air-to-air heat exchanger,the dehydrated air is raised in temperature by the

warm air entering the dehydrator. The heating ofthe air serves to reduce thermal shock as the airenters the system. The exiting dry air flows intothe receiver for availability to the ship’s air system.

DESICCANT AIR DEHYDRATOR(TYPE II)

Desiccant is a drying agent. More practically,desiccant is a substance with a high capacityto remove (adsorb) water or moisture. It also hasa high capacity to give off that moisture so thedesiccant can be reused. DESICCANT-TYPEDEHYDRATORS are basically composed ofcylindrical flasks filled with desiccant.

Compressed air system dehydrators use a pairof desiccant towers. One tower is in service

Figure 7-27.—Dehydrator (type I).

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dehydrating the compressed air while the otheris being reactivated. A desiccant tower is normallyreactivated when dry, heated air is routed throughthe tower in the direction opposite to that of thenormal dehydration airflow. The hot airevaporates the collected moisture and carries itout of the tower to the atmosphere. The air forthe purge cycle is heated by electrical heaters.When the tower that is reactivating has completedthe reactivation cycle, it is placed in service todehydrate air, and the other tower is reactivated.Figure 7-28 shows a desiccant dehydrator.

REFRIGERATION AND DESICCANTAIR DEHYDRATOR (TYPE III)

Some installations may use a combination ofrefrigeration and desiccant for moisture removal.

Hot, wet air from the compressor first enters arefrigeration section, where low temperatureremoves heat from the airstream and condenseswater vapor from the air. The cold, partially-driedair then flows into a desiccant section, where thedesiccant absorbs additional moisture from theair.

WASTE-HEAT BOILER

Steam for ship’s services is generated by threewaste-heat boilers using the hot exhaust gas fromthe ship’s service gas turbine generators (SSGTGs)as the heat source. The boilers are of theforced-recirculation, water-tube type. Ratedsteam capacity of each boiler is 7,000 pounds

Figure 7-28.—Dehydrator (type II).

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per hour (lb/hr) at a nominal operating pressureof 100 psig and a gas inlet temperature of650 °F.

BOILER CLASSIFICATION

Two types of waste-heat boilers are used ongas turbine ships. The first type is the Consecoboiler and the second type is the CombustionEngineering boiler. Both types of waste-heatboilers operate on the same principle. Theexhaust gases of the SSGTGs are used as theheat source to generate steam. For identification

purpose, the Conseco boilers found on theDD-963 and DDG-993 class ships have horizontalcoils of tubes; the Combustion Engineeringboilers found on the CG-47 class ships andthe DD-997 class ships have horizontal straighttubes.

BOILER CONSTRUCTION

In this section we are going to discuss only theConseco boiler. This boiler has a three-piece,gastight casing, the steam-generating coils or tubebundle, and four soot blowers. Hot exhaust gas

Figure 7-29.—Boiler components.

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from the SSGTG enters the boiler from thebottom, passes around and between the boilertube bundle, heating the water inside the tubes,and discharges through the side of the casing(fig. 7-29).

Casing

The casing, consisting of a half sectionand two quarter sections, is made with aninner wall, an outer wall, and a blanket ofspun glass insulation sandwiched in between.

Access ports are provided for maintenance andinspection.

Tube Bundle

The tube bundle (fig. 7-30) is made up ofsmooth bore, finned tubes. The tubes are woundin flat spiral coils and are assembled to the inletand outlet headers so the spaces between coilscoincide. This arrangement allows the flow ofexhaust gas around and between the tubes formaximum heat transfer with minimum pressuredrop across the boiler.

Figure 7-30.—Tube bundle.

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Steam Separator/Water Reservoir

The steam separator/water reservoir (fig. 7-31)is vertically mounted to the base adjacent to theboiler. It has a steam drum or flash chamber witha cyclone centrifugal steam separator, a dry pipe,and steam baffles. Steam separation takes placein the top of the unit, with the steam beingdischarged into the dry pipe connected to the topof the separator and the water being dischargedinto the lower part.

In operation, a mixture of steam and wateris discharged from the boiler into the steamseparator inlet connection, which is at a tangent

to the separator body. The mixture then passesthrough an orifice within the inlet connection,which causes it to increase in velocity as it entersthe separator. Because of the angle of entrance,increased speed, and a helical device within theseparator, the mixture acquires a rotary motion.Due to the rotary motion of the mixture,centrifugal force separates the water from thesteam. The water, being heavier, is thrown to thesides while the lighter steam remains in the center.An internal baffle further deflects steam to thecenter and water to the sides. The steam then risesthrough a scrubber element, which causes thesteam to change flow direction several times with

Figure 7-31.—Steam separator/water reservoir.

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further removal of moisture. From the scrubberelement, the steam passes through an orifice andenters the dry pipe, which carries it to the steamheader. The separated water falls to the base ofthe separator. Vanes in the base of the separatorserve to maintain the rotary motion of the wateruntil it is discharged from the outer edge of theseparator into the reservoir.

Connections are provided on the steam drumfor high- and low-water level control, feedwaterinlet, boiler-water outlet, and a water level sightgauge. A manhole provides access for inspectionand maintenance. Provision is also made forbottom blowdown and draining. The two safetyvalves, vertically mounted on the shoulder flangesof the steam separator drum, protect against over-pressurization. The valves are identical except fortheir pressure settings. Steam discharge from thesafety valves is piped to the exhaust gas outletduct.

Recirculation Pump

The purpose of the recirculating pump is toprovide a continuous flow of water from the

steam separator/water reservoir to the tubebundle and back to the steam separator. Thepump is capable of recirculating boiler water ata rate that exceeds the evaporation rate.

Control Condenser

The purpose of the control condenser is tocondense the excess steam resulting fromvariations of steam demand and exhaust gastemperature. The condenser (fig. 7-32) is ashell/tube design with the coolant (seawater)flowing through the tubes, It has the capacity tocondense the total boiler output at all operatingconditions.

Boiler Control Panel

The control panel is an integral part of thewaste-heat boiler. It contains the boiler controls,warning lights, an alarm bell, indicating lights,and gauges for local monitoring of all boileroperating parameters and steam distribution

Figure 7-32.—Control condenser.

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pressure. Figure 7-33 shows the boiler controlpanel.

Remote control and monitoring is providedat the propulsion and auxiliary control console(PACC). An emergency stop switch is the onlycontrol provided; when depressed, it auto-matically closes the steam stop valve.

STEAM PRESSURE CONTROL

Steam pressure control is accomplishedthrough control of the steam dump valve. Steamis discharged from the steam separator into a drypipe. The steam manifold splits into two lines ata Y connection. One line goes to the steam

Figure 7-33.—Boiler control panel.

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distribution header; the other line goes to thecontrol condenser. The steam stop valve is locatedin the line to the distribution header; the steamdump valve is located in the line to the condenser.The steam stop valve is normally closed andrequires air pressure to open; conversely, thesteam dump valve is normally open and requiresair pressure to close.

Steam Stop Valve

The steam stop valve is either open or shut.It is actuated by control air from the ship’sservice air system (SSAS). A solenoid valve, whenenergized, admits control air to the steam stopvalve actuator, opening the valve. De-energizingthe solenoid valve blocks the control air and ventsthe actuator to the atmosphere, causing the stopvalve to close.

Steam Dump Valve

The steam dump valve is modulated tocontrol the amount of steam diverted to thecontrol condenser. The steam pressure controllersenses steam pressure and regulates control air toposition the dump valve. An increase of steampressure causes a decrease of control air pressureand the dump valve tends to open. This divertssteam to the control condenser, thus reducingsteam pressure. A decrease of steam pressurecauses an increase of control air pressure and thedump valve tends to close; this increases steampressure. The steam dump valve can also bemanually operated.

FEEDWATER CONTROL VALVE

The feedwater control valve is a normallyclosed valve that requires air pressure to open.Valve control is automatic; a handwheel isprovided for manual operation if a failure occurs.

The feedwater control valve is modulated bythe leslie pilot controller to regulate thewater level in the boiler (steam separator/reservoir). The leslie pilot controller sensesthe water level in the steam separator/reservoiras a differential pressure and provides a variableair pressure to the feedwater control valveactuator to control flow. When the water levelrises, control air pressure reduces and the feed-water valve tends to close. When the water leveldrops, control air pressure rises and the valvetends to open.

The control air line to the feedwater controlvalve has two solenoid-actuated valves. They are

the high-water solenoid valve and the low-watersolenoid valve. Both valves are open (energized)during operation.

When boiler low-water level is sensed by a bartongauge micro switch and the water level remains low for2 minutes, an alarm sounds on the boiler control panel.This condition causes the Leslie pilot controller to routeair pressure to fully open the feedwater control valve.When boiler high-water level is sensed by the barton gauge microswitch, a signal is sent to a leslie pilot controller. This causes thecontrol air pressure being supplied to the feedwater control valveactuator to be blocked and vented to the atmosphere. If low-low waterlevel is sensed by the barton gauge, an alarm signal is generated, and therecirculation pump is stopped. The local control panel has low-water,low-low water, and high water level indicators mounted on thefront panel section. The PACC only has a summary fault alarm foreach boiler.

MISCELLANEOUS COMPONENTS

Some additional components that support theboiler operation are the chemical treatment tank,the blowdown valves, the soot blower system, andthe condensate collecting system.

Chemical Treatment Tank

The chemical treatment tank is provided forchemical treatment of the boiler feedwater.Parameters for boiler-water chemistry areprovided in Naval Ships’ Technical Manual,chapter 220.

Some ships have a continuous chemicalinjection system installed. It consists of a chemicalinjection tank that is filled with chemicals that areinjected into the system by a proportioning pump.

Blowdown Valves

Blowdown of the steam separator and theinlet and outlet headers is used for the removalof sludge and sediment. The blowdown isprovided for through an outlet on the bottom ofthe separator and through valves at the low pointof each header. The blowdown valves aremanually operated. These valves and theassociated piping are also used to drain the boiler.

Soot Blowers

The soot blowers consist of four stationarysteam lances positioned vertically between thecoils, 90° apart, and are controlled by individualvalves. Steam is discharged from holes in the lancearranged so that the steam covers all sides of the

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tubes. Soot, carbon, and combustion gas residueare discharged through the exhaust gas outlet.

Condensate Collecting System

The condensate collecting system collects thecondensate from the control condensers, distillingplants, and hot-water heating system and returnsit through the condensate main to the condensatecooler. This condensate is monitored for salinity.Figure 7-34 is a system schematic showing the flowof condensate, feedwater, and steam through thewaste-heat boiler.

CONTAMINATED DRAIN INSPEC-TION.—Condensate from the fuel or lube oilheaters is returned by the oily condensate main.From the oily condensate main, the condensatepasses through the contaminated drain inspectiontank where it is monitored for the presence of oilcontamination before returning to the condensatemain. The inspection tank is equipped with a UVoil detector that continuously and automaticallymonitors the condensate for oil contamination.When oil is detected, the associated solenoid-operated valve diverts the contaminated conden-sate to the waste-oil drain system. Alarmindicators are located at the control box and thePACC.

The alarm and warning circuits remainactivated as long as contamination remains abovethe set point. However, when contaminationdrops below the set point, the alarm and warn-ing indicator lights extinguish and the associatedsolenoid-operated valve closes. The contaminateddrain tank is equipped with a sight glass for visualinspection.

CONDENSATE COOLER.—The condensatecooler is of the shell and tube design with thecoolant (seawater) flowing through the tubes. Anair-operated valve in the seawater outlet pipingand an air temperature controller regulates theflow of seawater to control the output temper-ature of the condensate cooler.

SALINITY INDICATING SYSTEM.—Thesalinity indicating system monitors the condensatereturn system. The system has a bell and dumpmodule, salinity indicator and controllers, andsalinity cells for monitoring the control condenserand condensate cooler drains.

FEEDWATER AND DRAIN COLLECT-ING TANK.—The feedwater and drain collecting

tank collects the water from the condensate coolerand maintains a supply of water for the boiler.Makeup feedwater is supplied to the tank fromthe distilling plant. Additionally, provision ismade through an air gap (funnel) to the freshwatersystem for an emergency supply.

Tank level is automatically controlled by afloat-type level controller. When the water levelin the tank drops below a set level, the makeupfeedwater solenoid valve opens and makeup feed-water flows into the tank. When the tank is full,the makeup feedwater valve closes, thus shuttingoff the flow of makeup feedwater.

The level controller also contains switches forhigh- and low-water level indicating lights locatedon the boiler control panel and at the PACC.

FEEDWATER PUMP.—The purpose of thefeedwater pump is to supply feedwater to theboiler to maintain the proper water level in thereservoir during boiler operation.

DEAERATING FEED TANK.—An additionto the waste-heat boiler that is being installed onall ships at the present time is the deaerating feedtank (DFT) system. The purpose of this systemis the removal of gases in the feedwater which,in the case of oxygen, leads to corrosion andpitting of the internal surfaces of waste-heat boilertubes and other equipment.

The feedwater booster pump takes feedwaterfrom the feed and drain collecting tank and directsit to the subcooler. This feedwater is used to coolthe water from the DFT before it enters the feedpump. Feedwater leaves the subcooler and flowsthrough the DFT feed control valve. The DFTfeed control valve is an air-operated valve; itcontrols the flow of feedwater to the DFT. It isused to maintain normal water level in the DFT.A spillover valve is also used to prevent a high-water level from occurring and to maintain aminimum feedwater flow. Feedwater flow fromthe spillover valve is returned to the feed and draincollecting tank through the condensate cooler.

The deaerated water drops into the storagespace at the bottom of the DFT, where it remainsuntil it is pumped to the waste-heat boiler by thefeedwater pump. Meanwhile, the mixture of steamplus air and other noncondensable gases travelsup. The steam-gas mixture then exits the tank andflows to the external vent condenser. The remain-ing steam is condensed in the vent condenser andthe water is returned to the feedwater holdingtank, The air and other noncondensable gases are

7-34

Figure 7-34.—Steam system schematic.

7-35

vented to the atmosphere from the shell of thevent condenser.

Detailed procedures for operating and main-taining the waste-heat boiler are furnished by themanufacturers’ technical manuals, PMS, andthe EOSS. Carefully follow these writtenprocedures when you are operating or perform-ing maintenance on the waste-heat boiler.

OILY-WATER SEPARATOR Pressure vessels

The oily-water separator assembly processesthe oily waste water by separating the oil fromthe water. The process is based on the principleof coalescence. Figure 7-35 shows the generalarrangement of the components in the oily-waterseparator. Oily water is directed through speciallyconstructed filters that provide a surface uponwhich very small droplets of oil in the waterattach and combine (coalesce) with other oildroplets. When the oil droplets grow to sufficientsize, they are forced off the exterior surface ofthe filter by the fluid flow and are separated fromthe water. The difference in specific gravity

between the water and the oil and gravitationalforce cause the oil to rise and separate from thewater.

The oily-water separator contains the follow-ing main elements:

Motor controller

Motor-driven pump

Level detector probes

Pressure and differential pressure gauges

Liquid level sensor switch

The pump is a positive-displacement typeused to transfer liquid from the oily waste-waterholding tank to and through the three separatingstages. Mounted on the suction side of the pumpis a Y-type strainer to filter out large particles inthe fluid before it enters the first stage of thepressure vessels.

Figure 7-35.—Oily-water separator assembly.

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The three pressure vessels (stages) each havea removable cover that provides access to the filterelements. Mounted on each cover is an aireliminator valve to discharge any air displaced bythe effluent. Each vessel has a sight glass throughwhich water clarity and oil level can be monitoredand a manually operated drain valve for drainingthe stage. The first-stage vessel has a pressuregauge connected to monitor its fluid outletpressure. Connected into the second and thirdstages are differential pressure gauges that indicatethe difference between the inlet fluid pressure andthe outlet fluid pressure of each stage. The firsttwo stages have a capacitance-type level detectorprobe that senses an accumulation of oil andelectronically signals the opening of the solenoid-operated oil discharge valve.

The fluid enters the first stage (the gravityplate separator), where the primary separation andremoval of the oil from water is accomplished.Particulate matter, too small to be separated bythe duplex strainer, is removed for the fluid inthe first stage. The first stage is designed tosignificantly reduce the fluid velocity of theincoming oily mixture. The resulting decrease invelocity permits oily-water separation to occurnaturally from the effect of gravity. Oil drops inthe fluid are separated from the water due to thereduction in fluid velocity that occurs as the fluidexits the inlet line and enters the vessel interior.The oil drops rise and accumulate at the top ofthe vessel. Oil drops that do not rise to the topof the vessel are removed through coalescence bythe inclined adsorption plates on the bottom ofthe vessel. The plates provide a collection surfaceupon which any residual oil not gravitationallyseparated will collect (coalesce) and separate fromthe flow. Holes drilled in the plates permit the oildroplets to rise to the top of the vessel. Solids areremoved from the fluid in this stage. The airdisplaced by the rising fluid level in the pressurevessel is discharged through the automatic aireliminator valve mounted on the cover of thevessel.

The oil is automatically discharged from thefirst stage when the level detector probe senses theoil and electronically signals the simultaneousopening of the solenoid-operated oil dischargevalve and closing of the solenoid-operated cleanwater discharge valve. The valves remain inthe position until enough oil is discharged touncover the probe. This causes each valve toreturn to its original position, the clean water

discharge valve to open, and the oil dischargevalve to close.

The processed water effluent from the firststage is discharged into the second-stage prefilter.The second stage, which has a single prefilterelement, performs the dual function of removingparticulate matter and oil that were not separatedin the first stage. The replaceable prefilter elementis designed for inside-to-outside fluid flow. Asfluid flows from the inside to the outside of thefilter element, oil droplets form on the surface ofthe element. As the oil droplets form to sufficientsize, they are forced off the surface by fluid flow.This attach-detach process works solely throughfluid flow and requires no moving parts. Thedetached oil droplets rise and accumulate at thetop of the vessel. If an element becomes cloggedor its surface chemically contaminated, it iseasily replaced. When enough oil collects in thisstage to reach the level of the level detectorprobe, oil is automatically discharged in the samemanner as in the first stage.

The processed water next enters the third-stageseparator, which is identical to the second stagein its function and operation, except that it isequipped with a manually operated oil dischargevalve instead of a solenoid-controlled oil dischargevalve. Very little oil will accumulate in the thirdstage since most, if not all, of the oil will beremoved in the first two stages. The third stageserves primarily as a backup to the second stage.The clean water effluent leaves the third stage andenters the water discharge line.

The electrical circuit for the control power thatoperates the oil level sensors and the solenoid-operated valves is such that only one of theelectrically operated valves can be activated at agiven time. If simultaneous oil discharge signalsfrom both oil level sensors occur, the logic allowsonly one stage to discharge oil at any giventime. The system operation is fail-to-safe inthat all electrically operated valves close with-out power. The oily-water separator must bemanually started, but will be automatically shutdown when the liquid level sensor switch in theoily waste water holding tank drops to a presetlevel.

Detailed procedures for operating and main-taining the oily-water separator are furnished bythe EOSS, MRCs, and the manufacturers’technical manuals. Carefully follow these written

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procedures when you are operating or performingmaintenance on the oily-water separator.

SUMMARY

In this chapter, you have been presentedinformation that describes the basic constructionand operation of the different engineeringsupport and auxiliary equipment, such as pumps,

purifiers, air compressors, dehydrators, waste-heat boilers, and oily-water separators. Withoutthe proper operation and maintenance of thisequipment, the mission of the ship cannot beaccomplished.

The operation and maintenance described inthis chapter are not complete or inclusive. Youmust refer to the manufacturers’ technicalmanuals, PMS, or EOSS for specific operatinginstructions and maintenance procedures.

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CHAPTER 8

POWER TRAIN ANDCONTROLLABLE PITCH PROPELLER

When we use the term power train in ourdiscussions, we are using it as an overall term. Thisterm covers the equipment and various associatedcomponents that transmit the power developedby the GTE to the propeller.

The power train of today’s gas turbinepowered ships will consist of one or more of thefollowing components:

Main reduction gear (MRG)—reduces thehigh-power turbine speed to a lower usable shaftspeed.

Clutch and brake assembly—connects thepower turbine to the MRG.

Oil distribution box (OD box)—part of thecontrollable reversible pitch (CRP) propellersystem. It provides a means of sending hydraulicoil and prairie air (PA) through the gear and shaftarrangement to the propeller.

Propulsion shafting system-transmitspropulsion torque to the propeller, the resultantthrust to the thrust bearing, and accommodatesthe hydraulics system for the CRP propeller. Itconsists of the

propulsion shafting,

thrust bearing,

line shaft bearings,

bulkhead seals,

stern tube seals and bearings, and

strut bearings.

Hub-blade assembly-transforms thepropulsion shaft rotational torque into axial thrustfor ship propulsion. It also provides the mounting

for the propeller blades and contains the hydraulicservomotor mechanism for blade pitch control.

In this chapter, we will describe the powertrain, its component parts and their functions, andsystem relationships on gas turbine powered ships.Among the various classes of ships, manyvariations exist in the types of power trains.The overall function and principle of operationis the same in all of them. Some of these varia-tions are significant enough that they will becovered separately as that class of ship is beingdiscussed.

Upon completion of this chapter, you shouldhave the knowledge supporting the ability to (1)identify and describe the main components of thepower trains of today’s gas turbine ships; (2) alignand operate the GTE support systems; (3) operatethe pumps, the turning gears, the oil purificationsystems, and the engineering control systems fromtheir local operating stations; (4) check systemperformance; and (5) perform preoperationalchecks and preventive maintenance on the oilsystem.

MAIN REDUCTION GEAR (DD,DDG, AND CC CLASS SHIPS)

On these class ships, the MRGs transmit thepower developed by the propulsion GTEs to thepropulsion shafts. An MRG and its associatedequipment are located in each engine room. TheMRG performs two major functions:

It provides the flexibility of driving eachpropulsion shaft with either one or twoGTEs.

It reduces the high-speed rotation from thegas turbines to the low speed required forpropeller efficiency.

8-l

Fig

ure

8-1.

—M

ain

redu

ctio

n ge

ar.

Figure 8-l shows a typical MRG. This figuredoes not show the MRG in the proper perspectiveas to size. A typical MRG is 15.5 feet long, 16.75feet wide, 13 feet high, and can weigh as muchas 57.5 tons (115,000 pounds).

Multiple shaft ships have special needs whenit comes to the design of the power train. Toprevent steering problems or a tendency for thestern section of the ship to walk in the directionof shaft rotation requires that the shafts and

propellers produce what we call inboard rotation.That is, when viewed from the propeller end look-ing forward, the port shaft should rotate clockwiseand the starboard shaft should rotate counter-clockwise. The GTEs all rotate in the samedirection. This requires the MERs to be arrangedwith the port and starboard MRGs installed inreverse directions with respect to each other. Thisprovides the required inboard shaft rotation. Forclarity, figure 8-2 shows the rotating elements of

Figure 8-2.—Rotating elements.

8-3

a typical multishaft ship’s port and starboardMRG.

Numerous times you will be asked to describethe MRG. An acceptable description would bethat it is a double-helical, articulated, double-reduction, locked-train reduction gear with a21.49-to-1 reduction ratio. Double-reduction gearsets are used when the overall speed reductionratio exceeds 10 to 1.

To better understand the rotating elements ofthe MRG, refer to figure 8-2 as the name andfunction of each element is pointed out. The twohigh-speed input shafts (1) each drive a first-reduction (high-speed) pinion (2) through a clutchor clutch/brake assembly (3). The two first-reduction pinions each drive two first-reduction(intermediate) gears (4). The four first-reductiongears drive the four second-reduction pinions (5)through internal quill shafts and flexiblecouplings. All four second-reduction pinions drivea common second-reduction (low-speed) gear,commonly referred to as the bull gear (6). Thebull gear shaft is directly coupled to the pro-pulsion shaft (7). Integral with the bull gear shaftis a thrust collar, not shown on figure 8-2. Thethrust collar transmits the fore and aft thrust fromthe propeller via the propulsion shaft to the thrustbearing (8). The thrust bearing assembly isexternal to the reduction gear case. It is bolteddirectly to the propulsion bedplate aft of the gearcase.

First-reduction gear elements are referred toas high-speed (HS) elements and the second-reduction gear elements are referred to as low-speed (LS) elements. Figure 8-3 shows how theHS gear and LS pinion are connected by a quillshaft and an articulated flexible coupling to forma subassembly we call an intermediate assembly.Two intermediate assemblies provide a dual ortwin torque path in the power train from eachGTE. This arrangement, known as locked train,does not permit independent axial or rotationalmovement of the pinions. Each locked train mustbe timed to be sure that the load divides equallybetween the two intermediate assemblies.

Mounted on the forward end of each MRGat the end of the bull gear shaft is the OD box.The OD box is part of the CRP propeller system.The OD box serves two purposes:

It sends hydraulic oil and PA through therotating bull gear shaft and propulsionshaft to the propeller hub.

It positions a valve rod within thepropulsion shafting to control pitch.

On the DD and DDG-993 class ships, clutch/brakeassemblies provide the means to engage, dis-engage, stop power turbine rotation, or stop thepropulsion shaft. The CG and FFG, and DDG-51 class ships usea synchro-self-shifting (SSS) overrunning clutchto perform the same actions as the clutch/brakeassemblies on the DD and DDG-993 class ships.

An attached hydraulic oil pump for the CRPpropeller system is driven off the lower outboardsecond-reduction pinion shaft. An attached lubeoil pump is driven off the lower inboard second-reduction pinion. Both pumps are directly drivenvia bevel gears and flexible couplings and areconnected through manually operated disconnectcouplings. A turning gear assembly is connectedto the upper outboard second-reduction pinion.The upper inboard second-reduction pinion drivesthe tachometer generator, revolution counter, andelapsed time indicator.

GEAR CASING

The gear casing is a fabricated steel platestructure that encloses and supports the rotatinggear elements. A lube oil header is mounted ontop of the upper casing. It supplies lube oil forthe gears, bearings, SSS clutch, and clutch brakeassemblies. An opening on the bottom allows thelube oil to drain to the external sump. Coveredinspection ports permit visual observation of thelube oil impingement on the gear meshes and alsopermit gear inspection. The GTMs and the MRGare mounted on a common bedplate and arealigned before installation on the ship. Thecasing is secured to the bedplate by eight shockand noise attenuating vertical supports attachedto the bedplate and the base.

INPUT SHAFTS

The port and starboard input shafts are iden-tical on each MRG. Each input shaft is a flangedshaft mounted in two journal (sleeve) bearings.One end of the shaft is coupled to the GTE. Aturbine brake disc is attached to this end of theshaft. The opposite end of the shaft is attachedto the SSS clutch. A removable cover is providedfor access to the main section of the shaft. Atriseal shaft seal is mounted at the turbine end ofthe shaft to prevent oil leakage. This seal isdesigned as two halves that can be removedwithout removing the shaft or the bearings.

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Figure 8-3.—Intermediate assembly.

HIGH-SPEED PINIONS

The port and starboard HS pinions areidentical. Each pinion has double helical teeth fordriving its associated first-reduction gears. Theshaft is mounted in two sleeve bearings. An SSSclutch oil supply shaft is mounted on the insideof the HS pinion. This shaft is designed toprovide lube oil to the SSS clutch. On the star-board side, the HS pinion also drives thetachometer generator, revolution counter, andmagnetic speed sensor drive. On the port side, theHS pinion is connected to the output of the turn-ing gear. With this type of connection, motionis transferred through the port HS pinion to theremaining gears and pinions when the turning gearis being operated.

FIRST-REDUCTION GEARS

The port and starboard first-reduction gearsare identical. Each gear has double helicalteeth driven by the high-speed pinion. The

first-reduction gear is mounted on the same shaftwith the second-reduction pinion. The first-reduction gear portion of the shaft is mounted intwo sleeve bearings. A quill shaft is mounted in-side of the first-reduction gear and second-reduction pinion shaft. The quill shaft is rigidlyattached at the first-reduction gear end andconnected at the second-reduction pinion end bya dental coupling.

Each starboard quill shaft has a brake disc fora propeller shaft brake. The lower port quill shaftdrives the controllable pitch propeller (CPP)hydraulic pump drive.

SECOND-REDUCTION PINIONS

The port and starboard second-reductionpinions are identical. Each pinion has doublehelical teeth for driving the bull gear. The second-reduction pinion is mounted on the same shaftwith the first-reduction gear. The second-reduction pinion portion of the shaft is mountedin two sleeve bearings.

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BULL GEAR

The bull gear has double helical teeth that aredriven by the four second-reduction pinions. Itmay also be driven singly by either two port ortwo starboard second-reduction pinions. The bullgear shaft is mounted in two sleeve bearings. Apivoted shoe thrust bearing directs the propellershaft thrust, and its resulting thrust on the bullgear and shaft assembly, to the foundation. Asecond function of this thrust bearing is to main-tain axial position of the bull gear and shaftassembly.

A split bearing cap is provided for the thrustbearing. One half of the bearing cap containsprovisions for mounting a sight flow indicator formonitoring the flow of lube oil to the bearing.The other half of the bearing cap contains twoRTE connecters for remote monitoring of theoperating temperature of the ahead and reverseshoes of the thrust bearing. One of the RTEelements is located in the forward shoe and oneis located in the aft.

BEARINGS

Rotating elements of the MRG (input shafts,HS pinions, second-reduction pinions, bull gear,and so forth) are supported by bearings securedby bearing caps. They are called journal (sleeve)or tilt-pad bearings. The bearings (or bearing) thatevenly distribute the axial and radial torque of thepropeller shaft are called main thrust bearings.A removable bearing cap is provided for eachbearing. The bearing caps contain provisions formounting sight flow indicators for monitoring theflow of lube oil to the bearings. Each bearing isdesigned in two halves so the bearing can beremoved without removing the shaft. One half ofeach bearing contains an RTE that monitors theoperating temperature of the bearing.

Journal Bearings

The bearings supporting the first-reductiongears, second-reduction pinion, and second-reduction gear are split in half and doweledtogether. The shells are steel with a tin-basedbabbitt lining for the bearing surface. Drilledpassages through the shell and lining provide aflow path for lube oil. Reliefs in the babbittlining extend from the oil supply port to theends of the bearing. This arrangement assuresdistribution of lube oil across the full surface ofthe journal.

All gear elements, except for the input shaftsand first-reduction pinions, are supported byconventional babbitt-lined sleeve bearings. Thebearing bores are machined concentric to the out-side diameter and are designed for rebabbitting.Each bearing is marked with its crown thicknessat the time of manufacture. Bearing shells aremade in halves and doweled, serialized, and matchmarked to ensure proper assembly. Oil spreadergrooves are machined at the joints. Oil is admittedto the bearing surfaces through passages at thesplit line and distributed axially along thejournal by the spreader groove. Grooves areprovided at the ends of the spreader grooves toallow the flushing of foreign particles out of thebearing area. Holes are tapped in the bearingshells for inserting lifting eyes. Antirotation pinsare used to position the bearing shells at installa-tion and to prevent axial movement or rotationof the bearing shell during operation. Figure 8-4shows the construction of a typical sleeve bearing.

The journal bearings, supporting the inputshafts and first-reduction pinions, are the tilt-padtype. Since these two elements are the interfacebetween the MRG and the engines, they aresusceptible to gear misalignment resulting fromshaft motion and/or momentary minor misalign-ment caused by ship motion. The self-aligningfeature of the tilt-pad bearing corrects for thismisalignment. Additionally, the tilt-pad bearingwill dampen incipient shaft whip. For moredetailed information on the tilt-pad bearing,

Figure 8-4.—Construction of a typical sleeve bearing.

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refer to Main Reduction Gear, NAVSEA0910-LP-045-9500.

All of the journal bearings are pressurelubricated from the MRG lube oil system. Lubeoil is piped from the oil distribution header to eachbearing. It then flows through a passage machinedin the outside diameter of the bearing shells, intothe drilled passage in the shell and lining, and tothe bearing journal. A sight flow indicator isprovided in the oil drain passage of each bearingto permit visual observation of oil flow. A dial-type, bimetallic thermometer and an RTE areinstalled in the sight flow indicator to provide

local and remote indication of the temperature ofthe oil leaving the bearings.

Main Thrust Bearings

Propeller thrust is transferred from eachpropulsion shaft to the hull through a Kingsburymain thrust bearing (fig. 8-5). This bearing usesthe lubrication principle of the wedge-shaped oilfilm; that is, an oil film between two slidingsurfaces assumes a tapered depth with the thickerfilm at the entering side. In this assembly, eightbearing shoes are formed on each side of the

Figure 8-5.—Kingsbury main thrust bearing and housing.

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thrust collar; therefore, eight separate wedge-shaped oil films are formed on each thrust face.Since the bearing shoes are free to tilt slightly, theoil automatically assumes the taper required byshaft speed, loading, and oil viscosity. One thrustshoe on each side is fitted with an RTE.

Thrust is transmitted from the rotating thrustcollar to either (depending on ahead or asternpropeller pitch) of the two stationary eight-shoethrust rings. The rotating thrust collar is anintegral part of the second-reduction (bull) gear.

Besides transmitting propeller thrust to theship’s hull, the main thrust bearing also positionsthe other elements in the gear train. Since doublehelical gear teeth inherently trail together in mesh,the limited axial clearance permits the main thrustbearing to locate all rotating elements in thecasing space. This arrangement allows eliminationof thrust bearings on the HS rotors with attendantreduction of maintenance and power loss. Inoperation, the LS gear is positioned by the mainthrust bearing directly. The LS gear positions thefour LS pinions through the gear mesh. The gear-type couplings on the lower intermediateassemblies are designed to position the lower HSgears through the quill shaft. The lower HS gearsposition the HS pinions and upper HS gearsthrough the gear mesh.

BRAKE/CLUTCH ASSEMBLY(DD AND DDG-993 CLASS SHIPS)

Presently, two identical brake/clutch assem-blies are mounted on each MRG assembly, onefor each HS input shaft. These units willeventually be replaced by the SSS clutch used onthe FFG and CG, and DDG-51 class ships. The brake and clutchin each assembly provide independent functions.

The brake is a pneumatically operated,multiple-disc type of brake. When applied, it locksthe input shaft to prevent rotation of the GTE’spower turbine rotor (turbine braking). The brakesmay also be used to stop and prevent rotation ofthe propeller shaft. This can be accomplished onlywhen both brakes are applied and both clutchesare engaged. This process is called shaft brakingand is controlled by the ECSS.

The clutch is a pneumatically operated, oil-cooled, forced-synchronization, combinationfriction and dental type of clutch. The multiple-disc friction element is used to bring the inputshaft speed to within 11 rpm of the first-reductionpinion. The dental clutch then mechanicallycouples the input shaft with the pinion. When thedental clutch is engaged, all torque is transmitted

from the driving shaft to the driven shaft throughthe dental clutch. This engagement sequence iscontrolled by the control air system (COAS).Figure 8-6 shows the brake/clutch assembly.

Control Air System

Each brake/clutch assembly has one COASunit mounted on each side of the MRG on thebase flange below the lower second-reductionpinion. Each COAS unit contains all of thepneumatic and electronic components required forautomatic control and monitoring of thebrake/clutch assembly. Input requirements are28-volt dc power from the propulsion localcontrol console (PLCC) and 95 psig minimumcontrol air pressure from the ship’s service airsystem (SSAS).

The control components for each COAS unithave three solenoid air valve assemblies, twoprinted-circuit boards (PCBs) that control theoperation of the valves, and two air-pressureregulators. The primary regulator is set at 100 psigto provide pressure for brake and clutchoperation. The other regulator is set at 20 psigto provide a soft initial actuation of the brake.

The input parameters to the speed differentialrelay PCB are the input shaft and first-reductionpinion speed signals from magnetic speed pickupson the clutch housing. The speed differential relaycontrols the clutch engagement sequence. Itinhibits friction clutch engagement if the clutchinput and output shaft speed differential is greaterthan 1,500 rpm and inhibits the dental clutchengagement if the speed differential is greater than11 rpm.

Both brake and clutch operation is inhibited(can be overridden by key switches in CCS) if theoil inlet temperature is greater than 130°F and oilinlet pressure is less than 14 psig. If control airpressure is less than 95 psig, brake and clutchoperation is inhibited and cannot be overriddenby the CCS. Brake and clutch status is indicatedat the PACC and PLCC. A clutch cycle counteris also mounted in the COAS enclosure.

Clutch Sequencing

Magnetic speed pickups are mounted in theclutch housing and located directly over the teethin the outside diameter of the sleeve gear andclutch cup. They produce electrical impulsesproportional to the speed of the respective shafts.These signals are inputs to the electronicsenclosure in the COAS for automatic sequencingof the clutch operation.

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Figure 8-7.—SSS clutch assembly.

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SYNCHRO-SELF-SHIFTING CLUTCH

Identical positive drive SSS clutches connectthe GTEs to the MRG power train. Each clutchis supported by the input shaft and the HS pinioncouplings. The clutches permit operation witheither one or both GTEs driving the propeller.They also permit changing GTE combinationswhile the MRG continues to rotate. The clutchesare fully automatic, free-wheeling devices. Theytransmit torque (power) through splines and gearteeth machined in the clutch elements withoutexternal controls. Clutch engagement is initiatedby a pawl and ratchet mechanism.

Figure 8-7 shows a clutch assembly. Amanually operated lockout device prevents clutchengagement when actuated. The associated GTEcan then be operated independently of the rest ofthe power train. An indicator/switch unit

mounted on the gear case transmits clutch statusas ENGAGED/DISENGAGED to the controlconsoles. A hydraulic locking feature is providedin the design to prevent inadvertent clutchdisengagement during normal transient or shockconditions. A local visual indicator indicatesclutch status (ENGAGED or DISENGAGED).Two microswitches (situated in pairs for double-pole changeover action) are provided in eachclutch to give remote indication of these positions.The clutch is lubricated from an oil supply shaftmounted in the HS pinion bore.

The SSS clutch has an input assembly, a mainsliding assembly, a relay sliding assembly,and an output assembly. Figure 8-8 is across-sectional view of the clutch showingthe primary components. The clutch also has astatus indicator switch mechanism not indicatedin figure 8-8.

Figure 8-8.—SSS clutch (primary components).

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Clutch Engagement

The pawls and ratchet teeth are indexed toposition the internal and external relay clutch teethin line when the pawls engage the ratchet teeth.At this point, when the ratchet mechanismengages, a small axial force is developed. The relaysliding assembly is then forced to move axiallyalong the helical spline to engage the relay clutchteeth. The load on the ratchet mechanism developsthe small force required to shift the sliding relay.It is not subjected to the torque load in the mainpower train or to the force required to engage themain sliding assembly. The main sliding assemblyis engaged by the relay sliding assembly. Two setsof pawls and ratchets (primary and secondary) areused to avoid continuous ratcheting when theclutch is overrunning (clutch disengaged andreduction gear rotating).

Four primary pawls are mounted on the out-put assembly and rotate with the HS pinion. Thepawls are lightly spring-loaded to hold them in-ward to engage the external ratchet ring mountedon the sliding relay assembly. They are noseheavy. However, when the HS pinion speedexceeds approximately 500 rpm, centrifugal forceson the nose hold them out of contact with theprimary ratchet. This prevents continuousratcheting. As a result, these pawls are effectiveif the pinion speed is below 500 rpm (one-thirdidle speed). If the output assembly is rotatingabove 500 rpm (that is, the propeller shaft isbeing driven by the second gas turbine), theprimary pawls are centrifugally disengaged;therefore, they can play no part in meshing theclutch. For this reason, the secondary pawls areprovided. These pawls also line up with the relayclutch teeth at synchronism. From this point on,the clutch action is the same for whichever set ofpawls is operating.

Four secondary pawls are provided to engagethe clutch when the pinion speed is higher than500 rpm. These pawls are mounted on the relaysliding assembly, which is driven by the GTEthrough the input and main sliding assemblies.These pawls are nose heavy; when the powerturbine rotates, centrifugal force brings theminto action with the secondary ratchet ring, whichis a part of the clutch output assembly. When theoutput assembly is rotating at high speed and theinput assembly is stationary or at low speed, thesecondary pawls are held inward by a rim of oilformed centrifugally over the ratchet teeth;therefore, continuous ratcheting is prevented.When the power turbine accelerates, the relative

velocity between the oil rim and secondary pawlsdecreases and the centrifugal force on the noseof the pawls increases. When input speed reachesabout half the output speed, the increasedcentrifugal force on the pawl noses starts adampened ratcheting action. When input speedalmost reaches output speed, the pawls ratchetfully in preparation to engage the relay clutch atsynchronism.

An oil dashpot cushions the final movementof the main sliding assembly when the main clutchteeth approach full engagement. Figure 8-7 showsthe position of the dashpot on the SSS clutch. Thedashpot consists of a piston and cylinder formedby the flange of the support shaft and the boreof the main sliding assembly. While the relayclutch teeth are shifting the main sliding assembly,a large clearance exists around the dashpot piston.The clearance allows oil to be easily transferredfrom one side of the dashpot to the other. Justbeyond the point in the clutch travel at which therelay clutch teeth unload, this clearance reduces.Oil is then forced through small orifices in themain sliding assembly. The dashpot thus cushionsthe final mesh of the clutch, but it does notimpose high loads on the relay clutch mechanism.Because the dashpot is double acting, it also slowsthe disengagement rate.

Clutch Disengagement

When a GTE is shut down and the clutch in-put assembly slows relative to the outputassembly, a reverse torque is developed across themain helical spline. Continued reverse torque onthe relay helical spline shifts the relay and the mainsliding assembly to the fully disengaged position.Movement of the main sliding assembly actuatesthe clutch status indicator as the main clutch teethdisengage. During initial disengagement, thedashpot is active and disengagement is cushioned.The dashpot also tends to inhibit disengagementduring transient conditions where sustainednegative torque is not applied. The present designof the clutch is such that when a crashbackmaneuver is made (flank 3 to full astern), theclutch will automatically disengage for a periodof about 6 seconds. This is caused by the shaftoverrunning the power turbine speed.

Lockout Control

The manually operated lockout controlpermits operation of a GTE without rotation ofthe MRG. Figure 8-7 shows the position of the

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lockout control on the SSS clutch. It preventsinitiation of the clutch engagement sequence bydisplacing the pawls from respective ratchet rings.This mechanism is incorporated in the outputassembly and consists of a bevel pinion meshedwith an actuating ring (ring gear). A special toolis provided that unlocks and turns the pinion.

Lubrication

Lube oil from the MRG lube oil supply headeris supplied to the rotating parts of the clutchthrough the center of the HS pinion. The rotatingparts of the clutch and the thrust bearings absorbend thrust between the input shaft and the out-put connection of the MRG. The parts and bear-ings are supplied with oil through the center ofthe input shaft. The oil then discharges radiallyoutward through a third hole, while a fourth feedhole lubricates the relay sliding surface.

OIL DISTRIBUTION

The main lube oil service system supplies lubeoil to the MRG and accessories through the mainlube oil header. The headers are located at the topof the gear case. Gear and pinion teeth arelubricated and cooled by spray nozzles arrangedto direct oil across the full face width at the gearmesh. Oil flow to journal bearings and the mainthrust bearing is controlled by orifice plates. Theorifices are sized to allow sufficient oil flow forlubrication, but they restrict excessive flow ifextreme bearing wear or bearing failure occurs.The orifice plates are installed at the flangedconnection to each bearing, except in the case ofthe HS pinion and input shaft bearings. Orificeplugs are installed in the bearing seats in theselocations. Each bearing is equipped with a sightflow indicator and a bimetallic thermometer forlocal monitoring of oil flow and bearing oiltemperature. Nominal lube oil pressure is 15 psig.Minimum oil pressure at the hydraulically mostremote bearing is 5 psig. All ship classes have thesame basic lube oil service system. Again, we willcover them separately because of the differencesin design and setup.

DD, DDG-993, and CC Lube Oil Systems

The lube oil service system is a pressure feedsystem that delivers oil under pressure to the MRGheader and to each lube oil storage andconditioning assembly (LOSCA). All oil returnsto the supply reservoir (the MRG sump) to

complete the loop. The lube oil service systemincludes the following major components:

The lube oil sump

Two motor-driven lube oil service pumps

An attached (driven by the MRG) lube oilservice pump

A lube oil cooler

A duplex lube oil filter

A lube oil unloading valve

A lube oil heater

Interconnecting piping to the lube oil fill andtransfer system

The three pumps take suction from the lubeoil sump through check valves. The check valvesmaintain the pump’s prime and prevent reverseflow through a secured pump. The pumpssupply oil under pressure to a common line, wherethe unloader valve returns oil in excess of demandto the sump. Oil from the common line flows tothe lube oil cooler, where its temperature isreduced to approximately 120°F. From the cooler,oil flow is divided into two paths, one to supplythe MRG and the other to supply the two LOSCAcoolers. Oil to the MRG flows through the duplexlube oil filter into the MRG lube oil header. Fromthe MRG header, oil is distributed to lubricate andcool the reduction gear components, the brake/clutch assemblies, and the thrust bearings. Theoil then returns to the sump. Oil to each LOSCApasses through a pneumatically controlled(unloading) valve. This valve controls oil flow tothe synthetic lube oil cooler to regulatetemperature at the synthetic oil discharge. Servicesystem lube oil from the LOSCAs join in acommon line to return to the MRG sump.

Pressure regulation of the lube oil servicesystem is accomplished by control of the unloadervalve. The controller senses pressure at the inletconnection to the MRG oil header and regulatesthe unloader to maintain 15 psig minimum at theheader inlet. During normal operation, the motor-driven pumps are controlled by the ECSS. Theycan be cycled by a controlled sequence to main-tain adequate oil pressure at the MRG headerinlet.

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Correct temperature of the oil in the lube oilservice system must be maintained. If thetemperature of the oil in the lube oil service systemis below 90°F, the oil must be heated prior topropulsion plant operation. A motor-driven lubeoil service pump may be used to assist in theheating of the oil by circulating it through the lubeoil heater. The purifier is isolated from the heaterwhen this procedure is used. During thisoperation, a portion of the lube oil service pumpdischarge is diverted through the lube oil heaterand returned to the MRG sump. The remainingservice pump discharge oil is circulated aroundthe service system in the normal flow path. Thiswarms up the total system for plant operation.

MAIN REDUCTION GEAR LUBE OILSUMP.—The MRG lube oil sump is located inthe inner bottom beneath the MRG. The sumpcontains the supply of oil for the main lube oilservice system. It collects and retains oil as itreturns from the MRG, main thrust bearing, andpropulsion turbine synthetic lube oil systemcoolers. The lube oil return from the MRG to themain sump consists of a convoluted flexibleconnection bolted between the MRG oil pan andthe top of the sump. The normal operatingcapacity is 1,500 to 1,550 gallons, and the lowoperating level is 1,400 gallons. When the sumpis filled to the operating level, the pump suctionbellmouths will be submerged under all operatingconditions. The sump is designed to allow freedrainage of pockets formed by stiffeners insidethe sump and to allow access for inspection andcleaning. Lube oil return drains are located as faras possible from suction bellmouths. The sumpis equipped with a sludge pit located at the lowestpoint. It is also equipped with a liquid leveltransmitter, an RTE, pump and purifier suctionconnections, and oil return connections.

PUMPS.—Three positive-displacement lubeoil pumps are installed in each engine room, twomotor-driven and one attached to and driven bythe MRG. The attached lube oil pump is engagedor disengaged by a lever attached to the pumpcoupling. These pumps supply lube oil to theMRG and cooling oil to the two LOSCAs for thepropulsion gas turbines. The motor-driven pumpssupply oil to the system when the propulsion shaftis stopped and augment the attached pump at lowshaft speeds. When a lead pump has been selected,the motor-driven pumps are controlled by theECSS pump logic as a function of pressure at theinlet to the MRG lube oil header. The output of

the attached pump is not controlled and isproportional to shaft speed. Primary systempressure regulation is accomplished by theunloader valve. When the ship’s speed increasesand the total pump output exceeds the regulatingcapacity of the unloader, MRG inlet pressureincreases. The ECSS pump control logic thensequences the motor-driven pumps to change toa slower speed or to cut off to maintain pressurein the operating range. When the pump controllogic has sequenced both motor-driven pumps tocut off, the attached pump supplies the total lubeoil system requirements. A similar control se-quence operates to maintain oil pressure whenshaft speed decreases.

Motor-Driven Lube Oil Service Pumps.—Twoidentical lube oil service pumps are located in eachengine room. Each pump assembly consists of avertical-screw, positive-displacement pump thatis flexibly coupled to a two-speed electric motormounted on a common steel bracket. Resilientmounting is used between the bracket and theship’s structure. The pump is rated at 700 gpmat high speed and 250 gpm at low speed at adischarge pressure of 60 psig. The pumps takesuction from the MRG sump through a commonsuction line and discharge to the lube oil servicepiping.

A mechanical seal is located in the top endcover to prevent leakage along the pump shaft.Provision is made for installation of ring pack-ing above the seal. Packing should not be usedunless there is a failure of the mechanical seal.Lubrication is provided by the lube oil beingpumped. The mechanical seal is lubricatedthrough a tube and needle valve connected to thedischarge end of the pump.

The pumps may be controlled locally at theirrespective controllers. With the LOCAL-RE-MOTE selector switch in LOCAL, the STOP-SLOW-FAST selector switch is operative. Withthe LOCAL-REMOTE selector switch in theREMOTE position, control is transferred to theECSS.

The inlet to the MRG lube oil header isprovided with a pressure gauge, a thermometer,a pressure transducer, an RTD, and a pressureswitch.

The pressure transducer signal provides ameter reading at the PACC and the PLCC, aHEADER PRESS HI/LO light and alarm at thePACC and the PLCC, and information for datalogging. It also provides a high-low signal foralarm logging and provides information to the

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pump control logic at the PLCC for use in con-trolling the number of pumps in service and pumpspeeds.

The RTD provides a signal to the ECSS forthe following uses:

1. Meter reading of header temperature at thePACC and the PLCC

2. HEADER TEMPERATURE HI/LO in-dicator light and audible alarm at thePACC and the PLCC

3. Alarm logging

The pressure switch provides the permissivefor the MRG turning gear.

Attached Lube Oil Pump.—The attached lubeoil pump is of a similar design to the motor-drivenpumps. The principal difference is in the largersize and greater rated capacity. The attachedpump is rated at 1,140 gpm at 60 psig dischargepressure and 1,220 rpm (approximately 168 shaftrpm).

The attached pump is supported by a bracketimmediately above the lube oil sump top. It isdriven by the MRG lower inboard second-reduction pinion shaft through a right-angle drive.The angle drive is equipped with a manuallyoperated disconnect device that may be used todisconnect the attached pump when the main shaftis stopped. The attached pump takes suction fromthe sump through an individual suction line anddischarges into the lube oil service piping system.The pump speed is proportional to shaft speed;therefore, the attached pump does not deliverenough oil by itself to lubricate the MRG and tocool the GTE synthetic oil until higher shaftspeeds are reached.

LUBE OIL COOLER.—A lube oil cooler isinstalled in each lube oil service systemdownstream from the lube oil pumps to maintainthe oil outlet temperature at 120°F. The coolerconsists of a shell assembly, a tube bundle, andinlet and outlet water boxes.

The cooler is a single-pass shell and tubetype of heat exchanger. Seawater is used as thecooling medium. It enters the inlet water boxthrough the inlet connection, makes one passthrough the tubes, and is discharged through theoutlet water box. Seawater flow is regulated bya pneumatically operated valve controlled by atemperature sensor installed in the lube oilpiping downstream from the cooler. The lube oil

inlet is at the opposite end from the water inlet,resulting in counterflow heat transfer.

LUBE OIL FILTER.-—A duplex filter isinstalled in the piping downstream from the lubeoil cooler to remove particulate matter from thelube oil. The filter consists of a single cast steelbody mounted on a fabricated steel base. Thefilter body contains two filter chambers and adiverting valve assembly. The diverting valveconnects the filter chambers to the inlet and outletports. The filter chambers are covered by boltedsteel plates.

A manually operated changeover assemblypositions the diverting valve to place the right orleft filter element in service. The selector lever ispositioned over the chamber selected. A hydraulicinterlock prevents the shifting of oil flow toan open (nonpressurized) filter chamber. Aninterlock cylinder is connected to each of the filterchambers. When a differential pressure existsbetween the chambers, the cylinders engage anotch in the diverting valve cam plate andpositively lock the selector lever. The changeoverassembly also contains a balancing valve that isused to equalize pressure between the chambersto allow shifting. The assembly also fills the filterchamber after cleaning. Each filter chamber isprovided with a vent and a drain.

The liftout filter elements are constructed ofpleated wire cloth, supported by inner and outerperforated metal tubes. Magnets supported insideeach filter element remove ferrous particles fromthe oil.

A differential pressure gauge and switch areconnected to the inlet and outlet flanges for localand remote monitoring. The differential pressureswitch opens at 10 psid and sends a signal to theECSS. The ECSS activates the STRAINER DPHI light and alarm at the PACC and the PLCC,and provides data for alarm logging.

UNLOADING VALVE.—An unloadingvalve is located between the main lube oil headerand the MRG sump. It is controlled by a pressuresensor located at the MRG oil inlet. It is set tomaintain reduction gear inlet oil pressure at 15psig minimum under steady state conditions.

LUBE OIL HEATER.—One lube oil heateris installed in each engine room. The heater hasconnections to the purifier and to the lube oilservice piping system. The heater is used to heatthe oil during purification and to heat oil duringlube oil service system warm-up.

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Heaters are of conventional shell and U-tubedesign. Each heater is designed to raise the oiltemperature from 40°F to 90°F at 30 gpm andto 160°F at 4 gpm.

Oil enters at one end of the shell andmakes one pass through the heater as directedby the baffles. Ship’s service steam entersone end of the tubes through the inlet con-nection and makes one pass through theU tubes. Condensate is returned to the con-densate collecting system through the con-taminated drain inspection tank. The steaminlet valve is controlled by a temperaturesensor located in the oil outlet.

A temperature switch, sensing the oiltemperature at the heater outlet, opens at 170°Fand provides a signal for the ECSS. It is used tooperate HEATER TEMP HI alarm lights atthe PACC and the PLCC and for alarmlogging.

FFG Lube Oil System

The reduction gear lube oil service systemsupplies oil to the propulsion reduction gear andclutches for lubrication and cooling. The oilsupply also circulates through heat exchangers andacts as a coolant for the GTE lube oil servicesystem.

The reduction gear lube oil service system isa closed loop system with the sump tank ventedto the atmosphere. Circulation of lube oil isnormally accomplished by one service pump withthe other service pump on automatic standby. Athird pump that is pneumatically driven acts asa standby to the two service pumps and providesan oil supply to the reduction gear in case ofelectrical power failure on the ship. The systemis initially filled by the lube oil fill, transfer, andpurifying system.

The reduction gear lube oil service systemincludes the following components:

Lube oil service pumps (2)

Lube oil coast-down pump

Lube oil unloading valve

Lube oil temperature-regulating valve

Lube oil cooler

Lube oil discharge filter

Lube oil sump tank

LUBE OIL SERVICE PUMPS.—The pumpsare two-speed, electric-motor-driven, verticallymounted, screw-type pumps. The controls alloweither pump to be designated NORMAL with theother designated as STANDBY. The normalpump runs at low speed only for preheating thelube oil and runs at high speed during serviceconditions. With the pump controller mode switchin the AUTO position, operation of the pumpsis controlled by a set of pressure switches. If theoil pressure to the reduction gear hydraulicallymost remote bearing begins to drop below 13 psig,a pressure switch closes and causes the standbypump to start operating at low speed. If the oilpressure continues to drop below 11 psig, anotherpressure switch closes and the standby pumpswitches to high speed. A further drop in pressureto 9 psig closes a third pressure switch. It alsocauses the pneumatically driven, coast-downpump to start operating by opening the solenoidvalve to the pump’s air motor.

When the oil temperature is below 90°F,preheating is required. A connection to the lubeoil fill, transfer, and purifying system allows useof one of the lube oil service pumps to circulateoil through the lube oil purifier heater. Priminglines are provided at each pump so the operationof either service pump will maintain a continuousoil prime to the other two pumps. A relief valveset at 80 psig is located at each service pumpdischarge to protec t the sys tem f romoverpressurization.

LUBE OIL COAST-DOWN PUMP.—Thispump is a pneumatically driven, verticallymounted, screw-type pump. If the propeller shaftis rotating during an electric power failure on theship, the service pumps stop. The loss of pressurecauses the lube oil coast-down pump to start andcontinue to run until the propulsion plant can besecured. The duration of operation of this pumpis limited by the quantity of air stored in the HPair flasks provided in the engine room. Thedischarge of the coast-down pump goes into thereduction gear oil inlet header via the lube oilservice filter. The discharge bypasses the rest ofthe lube oil service system. A relief valve set at

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80 psig protects the discharge piping from over-pressurization. if the service pumps restorenormal system pressure to 15 psig, a pressureswitch opens and the air solenoid valve thatcontrols airflow to the pump motor closes andstops the coast-down pump. The coast-downpump also stops if the propulsion shaft comes toa stop.

LUBE OIL UNLOADING VALVE.—Theair-pilot-operated valve senses the oil pres-sure at the reduction gear’s hydraulicallymost remote bearing and regulates the oilsupply flow to maintain 15 psig at thatbearing. If the sensed pressure exceeds 15psig, the valve will open and return excesssystem flow to the lube oil sump tank.The valve is fully open at a sensed pressureof 20 psig. Control air from the ship’s LPvital air main is used for the operation of thisvalve.

LUBE OIL TEMPERATURE-REGULAT-ING VALVE.- The air-pilot-operated valve islocated at the inlet to the lube oil cooler andregulates the amount of oil flow through thecooler. The temperature-sensing element ismounted in the oil supply piping to the reductiongear. Based on the signal from the temperaturesensor, the valve regulates the amount of flowthrough the cooler and bypasses the rest. Thevalve is set to maintain a 110 ± 5 °F oil temperatureto the reduction gear. Control air from the ship’sLP vital air main is used for operation of thisvalve.

LUBE OIL COOLER.—This cooler is madeof two shell and tube type of heat exchangerspiped in series. Seawater from the main seawatercooling system circulates through the tubes in asingle pass through each shell of the cooler inseries. The lube oil flows through each shell inseries. The oil enters the cooler through theupper shell and leaves the cooler through the lowershell. Vent connections are provided on both theupper shell and water box, and drain connectionsare provided on the lower shell and water box.

LUBE OIL DISCHARGE FILTER.—Thisfilter consists of two separate filter housingsconnected by interlocked inlet and outlet valvesarranged so that only one housing is in operationat a time. Each filter housing contains 14 filter

elements rated at 65 microns. The filter elementscan be cleaned and reused. Vent and drainconnections are provided for each filter housing.

LUBE OIL SUMP TANK.—The sump tankis located below the propulsion reduction gear andis attached to the gear drain pan by an expansionjoint. The tank capacity at the normal oil levelis 1,400 gallons. The two service pumps and thecoast-down pump each have an independentsuction tail pipe from the tank.

Spent oil returns to the sump through anopening around the bull gear cover. Main ship’sstructural members in the tank act to smooth theturbulence in the oil return area. The pumpsuctions are located away from the turbulent areaso that the oil is permitted to deaerate beforeentering the suctions.

ATTACHED EQUIPMENT

The attached equipment, as we mentionedearlier in this chapter, consists of the turning gearmotor assembly, the attached lube oil and CRPpumps, the electrostatic vent fog precipitator,the dehumidifier, the shaft tachometer, therevolution counter and elapsed time indicator, theMRG instrumentation, the turbine brakes, andthe propeller shaft brakes.

With the exception of the MRG turning gear,all of the attached equipment is similar betweenthe DD, DDG-993, CG, and FFG class ships.

Turning Gear Motor Assembly

The turning gear motor assembly is mountedon the aft end of the port HS pinion. It isprimarily used to rotate the entire reduction geartrain for inspection and maintenance purposes.It can also be used on some ships to lock the mainshaft.

DD AND DDG-993 CLASS SHIPS.—Theturning gear is an electric-motor-driven, double-reduction gear mounted on the upper casingof the MRG. When engaged and operating,it rotates the propulsion shaft at approxi-mately 0.1 rpm. The turning gear drives theupper outboard second-reduction pinion througha manually operated engagement sleeve. A

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Figure 8-9.—Turning gear mechanism (DD and DDG class ships).

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three-position lever selects one of three posi-tions-ENGAGED, DISENGAGED, or SHAFTLOCKED. Figure 8-9 shows cross-sectional viewsof the turning gear mechanism in all three posi-tions. In the disengaged position, the handle canbe padlocked to a bracket to prevent accidentalmovement of the operating lever. Do not attemptto engage the turning gear while the reduction gearis operating. Also, do not attempt to operate theturning gear with the operating lever in the shaftlocked position. Either of these actions will resultin equipment or personnel casualties. With theturning gear engaged, the gear may be rotatedmanually with a wrench. A limit switch assemblyprovides electrical signals for TURN GEARENGAGED and SHAFT LOCKED indicators atthe PACC and the PLCC and a disengaged signalfor the ECSS logic. The MRG lube oil headermust have 15 psig of pressure to operate theturning gear motor.

The drive motor for the turning gear is a440-volt, 3-phase, 60-hertz electric motor, rated5 horsepower (hp) at 1,200 rpm. It drives theturning gear drive shaft through a worm gear. Theturning gear assembly is lubricated by oil spraysfrom the MRG lube oil supply header and a self-contained oil sump.

CG CLASS SHIPS.—An electric-motor-driven, double-reduction turning gear assemblyis mounted on each MRG (fig. 8-10). Whenengaged, the turning gear drives through theupper outboard second-reduction pinion. Theassembly consists of a 7.5-hp-driven motor anda double-reduction, spiroid/worm-type speedreducer. The turning gear assembly is attached tothe MRG through the second-reduction housingflange and the shaft lock ring (stop gear). Aflexible coupling attaches the drive motor shaftto the spiroid pinion in the first-reductionhousing. A coupling guard covers the flexiblecoupling. All bearings in the turning gearassembly are antifriction bearings. Lubrication isaccomplished by a combination oil immersion andspray system supplied from the MRG lube oilsystem at a rate of 3 gpm. The splined gears arespray-lubricated; the worm gears are lubricatedby gear meshes and bearings dipping into a self-contained reservoir.

Two shifting levers are provided with theturning gear. The shaft lock shifting lever ismounted on top of the unit and is used to lockthe shaft adapter to the shaft lock ring. The otherlever, the turning gear shifting lever, is mountedon the back of the turning gear assembly and is

Figure 8-10.—Turning gear assembly (CC class ships).

used to engage and disengage the turning gearclutch.

The shaft lock shifting lever moves the shaftlock clutch with a shifting yoke. An index plate,mounted on the housing, and an indicator plate,mounted on the worm shaft, make up a turninggear shaft lock vernier. This vernier indicateswhen shaft lock male clutch teeth are in line withthe female clutch teeth attached to the turning gearhousing. The shaft lock shifting lever locks theshaft lock movable male clutch teeth to thestationary female clutch teeth attached to theturning gear housing. Plates on the gear lock limitswitch bracket identify two positions of the shaftlock shifting lever: SHAFT UNLOCKED andSHAFT LOCKED. The vernier indicator is usedto align the clutch teeth, while an open-endwrench is used to rotate the shaft during matingof the teeth. Limit switches send signals to the

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ECSS to indicate the status of the shifting lever.Override stops are provided on the clutch andshaft lock limit switch brackets to prevent theshifting levers from moving past the microswitchpositions.

The turning gear shifting lever is connected tothe turning gear clutch via the clutch shaft.Shifting this lever can engage or disengagethe clutch from the shaft adapter. The shiftinglevers can be padlocked to the disengagedpositions to prevent accidental engagement ofthe turning gear while the MRG is operating.Two plates on the clutch limit switch bracket iden-tify the shifting lever position: TURNING GEARDISENGAGED and TURNING GEARENGAGED. The connect-disconnect couplingmoves in the axial direction to engage ordisengage. The shifting lever axially engages ordisengages the internal gear teeth with matingteeth on the end of the second-reduction pinionshaft.

The turning gear provides a means for rotatingthe propeller shaft while the propulsion plant isshut down. The second-reduction gear shaft andpropeller shaft rotate at about 0.1 rpm with theturning gear engaged and operating. This slowspeed permits inspection of the MRG gear teeth.The slow rpm also permits MRG cooldownwithout shaft distortion or bending. Turning alsoprevents propeller shaft bowing. The circuitpermissives which must be satisfied to engagethe turning gear are as follows:

Shaft not locked

Greater than 9 psig lube oil pressure

No GTE running

No clutch engaged (Turning gear motor can-not be engaged if either clutch is engaged.)

FFG CLASS SHIPS.—Figure 8-11 shows theturning gear assembly on the FFG class ships. Itis mounted on the aft end of the port HS pinion.It has a shift lever for engagement or disengage-ment. Two microswitches associated with the shiftlever provide electrical signals to the propulsioncontrol console (PCC) and the local operatingpanel (LOP) when the shift lever is engaged ordisengaged.

The turning gear assembly includes a 5-hpelectric motor that operates from a 440-volt,60-hertz, 3-phase power source, The couplingbetween the electric motor and the turning geartrain includes a mechanically operated brake. Thisbrake is used to lock the turning gear and mayalso be used to lock the entire reduction gear train.

Figure 8-11.—Turning gear assembly (FFG class ships).

When the turning gear is locked, a microswitchthat is actuated by the brake lever provides a brakelocked signal to the PCC. A handwheel is alsoprovided for turning the turning gear manually.The gearbox for the turning gear has a worm geardrive system.

The electric motor is controlled by a magneticcontroller that is mounted remotely from theMRG. The motor is designed to operate in eitherthe forward or reverse direction.

Lubricating Pump

The lube oil system in each MER incorporatesthree positive-displacement pumps. Two of thepumps are driven by electric motors, while thethird is driven by the MRG and is designated theattached pump. The purpose of the attachedpump is to augment the output of the electricpumps during propulsion plant operation. Thispump is a vertical-screw, submerged-suctionpump, with a nominal flow of 1,140 gpm at 1,220rpm pump speed. The motor-driven pumps areof similar construction, but they have a smallercapacity.

The attached pump is driven by the lowerinboard second-reduction pinion shaft through amanually operated connect/disconnect couplingand a right-angle drive unit. Figure 8-12 showsthis right-angle drive.

8-20

Figure 8-12.—Attached lube oil pump drive.

The coupling has two sleeve gears and a slidinggear. One sleeve gear is keyed to the pump driveadapter on the second-reduction shaft and theother is keyed to the horizontal drive shaft of thedrive unit. The sliding gear is splined to the sleeve

gear on the horizontal drive shaft. A yoke fitsaround the sliding gear, and the engagement leveris attached to the yoke. When the engagementlever is moved to the engage position, the yokemoves the sliding gear axially on the drive shaft

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sleeve gear coupling and engages the sliding gearwith the sleeve on the pinion shaft. The engage-ment lever position is marked on a plate on thedrive housing under the lever handle. Thehandle can be locked in either the ENGAGED orDISENGAGED position (see detail A on fig.8-12). No remote status indication is provided. Aphotoengraved plate should be visible, adjacentto the unit, with the following caution message:

CAUTION

Do not attempt to engage or disengage themanually operated attached lube oil pumpdrive coupling while the reduction gear isin operation.

This action will result in equipment orpersonnel casualties. However, you can dis-connect the pump drive couplings while the MRGis in operation if an emergency occurs.

The drive unit has a drive assembly housing,a horizontal drive shaft, a spiral bevel gear set,and a vertical drive shaft. The horizontal shaftdrives the vertical drive shaft through the set ofspiral bevel gears. The vertical drive shaft drivesthe attached pump through an extension shaft.The extension shaft is attached to the pump andthe drive unit through flexible couplings. Thepump drive and disconnect coupling unit islubricated by sprays from the MRG lube oilsystem. The vertical couplings are grease-lubricated.

Controllable ReversiblePitch Hydraulic Pump

The backup hydraulic oil pump for the CRPpropeller is attached to the MRG. It is driven bythe lower outboard second-reduction pinionthrough a manually operated, connect/disconnecttype of coupling and spiral bevel gear right-angledrive assembly. The coupling/drive unit is similarto the coupling drive unit for the attachedlube oil pump. The main difference is that thehorizontal bevel gear on the coupling/drive unitis mounted on the MRG side of the vertical bevelgear to give opposite rotation to the output shaft.The output shaft is coupled to the pump througha flexible coupling. The attached CRP hydraulicoil pump is similar to the hydraulic oil powermodule (HOPM) motor-driven pump, which wewill discuss further along in this chapter. Duringnormal operations, NEVER attempt to engage or

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disengage the manually operated attached CRPhydraulic oil pump coupling while the reductiongear is in operation. However, you can dis-connect the pump drive couplings while the MRGis in operation if an emergency occurs.

Electrostatic Vent Fog Precipitator

The electrostatic vent fog precipitator ismounted in the lube oil system vent piping. Thepurpose of the vent fog (mist) precipitator is toremove entrained oil mist from the MRG vent airbefore it is discharged into the engine room. Themist precipitator is a two-stage, electrostatic type,capable of removing 95 percent of the entrainedoil from the vent air at an airflow rate of 10 cfm.It has a charging element (ionizing section), acollecting element (collecting section), and anintegral power supply. The power supply convertsthe input voltage, which is 120-volt, single-phase,60-hertz, to l0,000-volt dc.

Figure 8-13 shows the operating principle ofthe vent fog precipitator. In operation, the MRGvent air enters the precipitator through a flamearrestor mounted in the inlet plenum. The oilparticles in the vent air are electrically charged(positively,) as they pass through an ionizingsection. In the ionizing section, a high con-centration of ions emanate from the ionizerelectrode suspended in the center of and at theentrance to the collector tube. The ionizerelectrode is charged with high-voltage dc and thecollector tube is electrically grounded.

The positively charged oil particles then passinto an electrical field set up within the collectortube. The field is created by a positive, high dcvoltage being applied between the high-voltagetube and the collector tube. The positively chargedoil particles are attracted and adhere to the wallof the negative (grounded) collector tube. As moreparticles collect on the collector tube wall, theyform an oil film, which runs down the wall intothe inlet plenum. From the inlet plenum, the oildrains into the MRG. The cleaned vent air isdischarged into the engine room.

The air discharged from the precipitatororiginates primarily from changes in operatingconditions that cause temperature changes in theMRG. Expansion and contraction of the oil andair inside the MRG result in air being aspiratedinto the gear case. Other possible sources ofaspiration of air are moving HP and LP areasinside the case (caused by rotation of the gears),which result in aspiration of air, gasket and sealleaks, and strainer changing.

Dehumidifier

Figure 8-13.—Vent fog precipitator.

Many gas turbine ships now have a de-humidifier permanently installed on each MRG.The purpose of the dehumidifier is to maintainthe air within the MRG casing at less than 35 per-cent relative humidity when the MRG lube oilsystem is secured. The dehumidifier is notnormally operated while the ship is underway.Detailed procedures for operating and main-taining dehumidifiers are furnished by themanufacturers’ technical manuals, PMS, and theEOSS. Carefully follow these written procedures

8-23

when you are operating or performingmaintenance on dehumidifiers.

Shaft Tachometer

Each MRG has two tachometer generators toprovide an electrical signal for remote indicationof propulsion shaft speed. The generators aredriven off the upper inboard second-reductionpinion shaft. The drive assembly consists of adrive housing, a drive adapter, a drive ring, anda gear train with three quill shafts. The driveadapter and drive ring are connected to the

second-reduction pinion. The gear train pinion isdriven by the drive ring and in turn drives the threespur gears. Two of the spur gear drive the twotachometer generators through quill shafts (thethird gear drives the revolution counter andelapsed time indicator).

The output signal from each tachometergenerator consists of voltage pulses generated atthe rate of 512 pulses for each propeller shaftrevolution. The signal voltage and pulse width aredetermined by the rotational speed of thetachometer drive assembly. The tachometersignals pass through separate amplifiers locatedon the MRG casing near the tachometer enclosure.After being amplified and converted to 256 pulsesper shaft revolution, the tachometer signalsenter the signal conditioning enclosure (S/CE).Comparison circuitry, within the S/CE selectsthe strongest tachometer signal and sends it onto the rest of the ECSS for logging and displayof shaft speed. The tachometer (quill) shaftmust be turning at least 30 rpm for a reliablereading.

DANGER

Do not attempt to work on the ta-chometer system while it is in theautomatic propulsion mode. A loss ofsignal from the tachometer could cause anundesirable or dangerous propulsion plantresponse.

Revolution Counter andElapsed Time Indicator

The revolution counter is mounted adjacentto the tachometer generators and is driven bythe same drive assembly. The unit provides alocal, digital display of total propulsion shaftrevolutions and elapsed time at specific shaftspeed ranges. Figure 8-14 shows the face of theunit.

Tachometer Generator, RevolutionCounter, and Magnetic Speed Sensor Drive

On the FFG class ships, the tachometergenerator, revolution counter, and magnetic speedsensor drive are driven by the starboard HS

Figure 8-14.—Revolution counter and elapsed timeindicator.

pinion. It contains provisions for connectinga tachometer generator, a revolution counter,and a magnetic speed sensor. The tachom-eter generator and revolution counter aredriven at exactly 50 percent of the propeller shaftspeed.

MRG Instrumentation

A liquid sight indicator (fig. 8-15) is providedat each main bearing. Each indicator has afitting containing a window (bull’s eye) throughwhich a stream of oil can be observed flowingfrom the bearing, a fitting for a dial-typethermometer, and a well for installation of aremote-reading RTE.

Lube oil pressure at the inlet to theheader is sensed by both a pressure transducerand a pressure switch. The transducer sendssignals to the ECSS for METER/DDI dis-play, pump logic operation, data logging,and HEADER PRESS HI/LO alarming at thePACC and the PLCC. The pressure switchprovides the permissives for the turning gear andGTE starting.

The most remote bearing lube oil pressure issensed by a transducer located at the lower

8-24

Figure 8.15.—Liquid sight indicator.

outboard first-reduction gear (forward port-aft to open or close electrical contacts at the setstarboard) bearing. point.

A temperature switch, located in the A temperature transducer, located at thebrake/clutch oil inlet, is set to open contacts inlet to the header, provides both meter displayat 130°F to prevent brake/clutch operation. and HEADER TEMP HI/LO alarm at the PACCA temperature-sensitive bellows actuates a switch and the PLCC.

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FFG Turbine Brakes

Each input shaft is equipped with a singledisc caliper brake assembly. Figure 8-16 shows atypical turbine brake assembly. Each brake ispneumatically operated and is self-retracting. Thebrake includes two brake pads, one on eachside of the brake disc. Since the brakes arc

self-adjusting, they always maintain the properclearance.

The brakes are controlled by individualsolenoid valves in the turbine brake panel so theymay be engaged independently of each other. Thesolenoid valves are controlled electrically at thePCC and the LOP. The valves may be actuatedmanually at the turbine brake panel (fig. 8-17).

Figure 8-16.—Typical turbine brake assembly.

8-26

Fig

ure

8-17

.—T

urbi

ne b

rake

pan

el.

A pressure switch associated with each solenoidcontrol valve provides an electrical signal whenthe brake is engaged. A low-pressure alarm switchis also provided in the turbine brake panel toprovide an electrical signal whenever the input airpressure drops below 70 psi. Normal operatingpressure is between 70 to 125 psi. An air receiverat the inlet to the turbine brake panel maintainsa constant volume for brake engagement.

Shaft Brakes

A propeller shaft brake assembly (fig. 8-18)is mounted on each starboard first-reduction quillshaft. Each brake assembly has three disc caliperbrakes, The disc caliper brakes are pneumaticallyoperated and are self-retracting. Each brakeincludes two brake pads, one on each side of the

brake disc. Since the brakes are self-adjusting,they always maintain the proper clearance.

Both brake assemblies are controlled by asingle solenoid valve in the propeller shaft brakepanel (fig. 8-19). The solenoid valve is controlledelectrically at the PCC, the LOP, or the SCC. Thevalve may be actuated manually at the propellershaft brake panel. A pressure switch associatedwith the solenoid valve provides an electricalsignal when the brakes are engaged. A low-pressure alarm switch is also provided in thepropeller shaft brake panel. The alarm switchprovides an electrical signal whenever the inputair pressure drops below 1,150 psi. Normaloperating pressure is 1,250 psi reduced down from3,000 psi. An air receiver at the inlet to thepropeller shaft brake panel maintains a constantvolume for brake engagement.

Figure 8-18.—Typical propeller shaft brake assembly.

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CALIPERBRAKEBLOCK

CALIPERBRACKET

DISC CALIPERBRAKE

INPUT AIRHOSE

CALIPERBRACKET

CALIPER BRAKEBLOCK

DISC CALIPERBRAKE

OUTER SIDEPISTON SUBASSY

RETRACTORCOVER

BRAKE PADS

INNER SIDEPISTON SUBASSY

CALIPERBRAKEBLOCK

SHAFT OILSEAL ASSY

AIR HOSE

DISC CALIPERBRAKE

AIR HOSESHAFT BRAKE

HOUSING

Fig

ure

8-19

.—P

rope

ller

shaf

t br

ake

pane

l.

An air filter (shown on fig. 8-l) is providedat the output of the propeller shaft brake panelto provide constant filtering of the air applied tothe propeller shaft brakes. This air filter containsa replaceable element.

CONTROLLABLE PITCHPROPELLER SYSTEMS

The ship’s propulsive thrust is provided by ahydraulically actuated propeller or propellers,depending on the class of ship. Each propeller isdriven by two GTEs through a reduction gearassembly and line shaft as previously described.Since the GTEs cannot be reversed, the CRPpropellers provide both ahead and astern thrust,thus eliminating the need for a reversing gear. Thefollowing description of the CRP system is basedon the DD-963 class ships; systems on theDDG-993 and CG-47 class ships are basically thesame as the controllable pitch propeller (CPP)system on the FFG class ships. For a morethorough description of your ship’s system, checkthe shipboard technical manuals and ship’sinformation books.

The CRP propeller system for the propulsionshaft consists of the propeller blades and hubassembly, the propulsion shafting, hydraulic andpneumatic piping and the control rod containedin the shaft, the HOPM, the OD box, thecontrol valve manifold block, the electrohydrauliccontrols, the hydraulic oil sump tank, and thehead tank. Figure 8-20 shows a block diagram ofthe system.

The CRP propeller has five blades. The bladepitch control hydraulic servomotor, mechanicallinkage, and hydraulic oil regulating valve arehoused in the propeller hub/blade assembly.High-pressure hydraulic control oil is provided foreach propeller by the HOPM that is locatedadjacent to the reduction gear. An OD box,mounted on the forward end of the reductiongear, is mechanically connected to the hydraulicoil regulating valve by a valve control rod. TheOD box contains the hydraulic servomechanismthat positions the regulating valve rod. The ODbox also provides the flow path connectionbetween the hub servomotor and the HOPM. Theregulating valve control rod, PA piping, and theflow path for the hydraulic oil supply and returnare contained in the hollow propulsion shafting.

Figure 8-20.—CRP propeller system block diagram.

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A control valves manifold block assembly,mounted on the side of the OD box, containscontrol valves for both manual and automatic(electronic) pitch control. The manual controlvalves consist of a manual pitch controlvalve and two manual changeover valves.Automatic pitch control is accomplished throughan electrohydraulic control oil servo valve. Thisvalve responds to an electrical signal generatedfrom the shipboard electronics.

HUB/BLADE ASSEMBLY

The hub/blade assembly provides the mount-ing for the five propeller blades and contains thehydraulic servomotor mechanism for blade pitchcontrol. It also transforms propulsion shaftrotational torque into axial thrust for shippropulsion. The hub body is secured to thetailshaft flange by 15 bolts and 5 dowel pins. Therotational torque of the propulsion shaft istransmitted to the hub by the five dowel pins. Thehub/blade assembly has the following majorcomponents (fig. 8-21):

Hub body assembly

Piston and piston rod assembly

Crosshead and sliding blocks

Regulating valve

Blades and blade bolts

Crankpin rings

Blade seal base rings

Tailshaft spigot

Blade port covers

Hub cone cover and hub cone end cover

Hub Body Assembly

Propeller blade pitch is hydraulically con-trolled by the hydraulic servomotor. The servo-motor, consisting of the piston, the piston rodassembly, and the regulating valve, is containedwithin the hub body. A one-piece crosshead issecured to the forward end of the piston rod. Thehub body forms the crosshead chamber with thetailshaft spigot enclosing the forward end of thechamber and the hub body end plate enclosingthe aft end. The servomotor cylinder is formedby the hub body end plate and the hub cone. Thepiston rod extends through the bore in the hubbody end plate into the crosshead chamber.

Figure 8-21.—Cross-sectional view of the hub/blade assembly.

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Five sliding blocks fit into slots machined inthe crosshead. The hub body contains five bladeports with a center post in each port. The centerposts are integral parts of the hub body. Acrankpin ring fits over the center post in the bladeports. An eccentric crankpin on the underside ofeach crankpin ring fits into a hole in each slidingblock. When the servomotor piston is translatedas a result of differential pressure across thepiston, axial movement of the crosshead producesrotary movement of the crankpin rings throughthe sliding blocks and eccentric crankpins. Thepropeller blades, which are secured to thecrankpin rings, arc thus rotated, resulting in thedesired pitch change.

Figure 8-22 shows the hub assembly regulatingvalve, consisting of a valve liner and a valve pin,which controls the position of the servomotorpiston. The valve liner is secured in the piston rodbore. Ports in the forward and aft ends of the linerprovide a flow path for hydraulic power oil to theforward and aft chambers of the servomotorcylinder. The valve pin fits inside the valve linerand moves axially within the liner. The amountof axial travel of the pin in the liner (1/2 inchtotal) is limited by a machined shoulder on thepiston rod bore. The valve pin contains hydraulicpower oil ports in the forward and aft ends andreturn oil ports centered between. Axial move-ment of the valve pin is controlled by the valverod connected to the valve pin at the aft end andto the OD box at the forward end.

When the valve rod is moved in the forwarddirection, the aft hydraulic power oil ports in thevalve pin align with the aft ports in the valve liner;the return oil ports in the valve pin align with theforward ports in the valve liner; and the forwardports in the valve pin are blocked off. Thus,hydraulic power oil at 200 to 600 psig is directedto the aft chamber of the servomotor cylinder.The forward chamber of the cylinder is openthrough the return oil ports. The resultantpressure differential across the servomotor pistoncauses the piston to move forward. This resultsin a change of blade pitch in the ahead thrustdirection. During pitch translation, the piston rod,valve, and valve rod move together. Pitch transla-tion continues until movement of the valve rodstops and the valve pin is centered in the valveliner. When the valve rod is moved in the aftdirection, the action is reversed, resulting in pitchchange in the astern direction.

When the valve pin is centered in the liner,both ports in the liner are blocked off. However,reliefs machined in the valve pin lands permit a

continuous flow of hydraulic power oil to bothsides of the servo piston. The continuous flowresults in a balanced pressure across the piston,holding the blade pitch constant. In this position,hydraulic pressure on both sides of the piston issufficient to hold the desired blade pitch regardlessof changes of blade thrust loading.

The flow path for the hydraulic power oil isfrom the OD box through two drilled passagesin the regulating valve rod, through the valve rod,and into the hollow valve pin. The oil returnsthrough the valve pin return ports, which arecontinuously indexed to slots in the valve liner.It then flows into the chamber formed by the out-side diameter of the valve rod and inside diameterof the propeller shaft and to the OD box. A PAtube runs through the regulating valve rod andvalve pin from the OD box to the cone end cover.

Blades

Each propeller has five blades. The blades aremade of nickel bronze alloy and weigh 4,300pounds each. Each blade is attached to a crankpinring with eight bolts. A machined air channel runsalong the blade leading edge from the root to theblade tip. This channel provides the flow path forPA, which discharges through small orificeslocated along the leading edge. Prairie air isdelivered to the blades through the PA tube thatruns through the regulating valve rod from theOD box to the hub cone. Drilled passages in thehub cone and hub body to the blade basecompletes the flow path. A check valve in the hubcone prevents seawater from entering the PAsystem when air is not flowing.

Blade Seal Base Ring

A blade seal base ring is located under theouter edge of each blade port cover. The purposeof the seal base ring is to prevent oil fromleaking out of the hub and seawater from leakinginto the hub. Each seal base ring has two O-rings.One provides the seal between the seal base ringand the blade port cover; the other provides theseal between the seal base ring and the hub body.Eighteen compression springs under the seal basering provide positive loading of the ring againstthe blade port cover.

Tail-shaft Spigot

The tail-shaft spigot has the physicalappearance of a short shaft with a flange on one

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Figure 89-22.—Hub assembly regulating valve.

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end. It is bolted to the forward end of the hubbody concentric with tail shaft. The tail-shaftspigot, with the shaft portion extending into thecrosshead chamber, encloses the forward end ofthe chamber. The shaft portion of the spigot isthe same diameter as the piston rod. It serves asa guide and support for the piston rod andcrosshead as they move axially, during propellerpitch translation.

The crosshead chamber is designed to containa constant volume of oil to prevent pressure surgescaused by variable seal loadings. Variable sealloadings are caused by piston rod travel withinthe chamber during pitch translation. As thepiston rod moves into or out of the crossheadchamber during pitch translation, it changes thechamber volume. The forward end of‘ the pistonrod covers or uncovers an equal volume of thetail-shaft spigot, thereby cancelling the effect ofvolume change.

Two low-pressure safety valves are located inthe tail-shaft spigot. One of these valves is shownin figure 8-21. Overpressurization in the crossheadchamber, resulting from expansion of the oilcaused by thermal change, opens the safety valvesand bypass oil to the return oil passage. If thereturn oil pressure exceeds the crosshead chamberpressure, the oil can flow past the piston rod sealinto the crosshead chamber.

The hub purge valve is located in the hub bodyend plate that separates the servomotor cylinderfrom the crosshead chamber. The purpose of thepurge valve is to purge oil from the forwardchamber of the servomotor cylinder when thepropeller is stroked beyond its design full asternpitch limit. If the propeller is stroked beyond itsdesign full astern limit, the crosshead contacts thepurge valve, causing the valve to open. Theopen valve permits oil to flow from thecylinder into the crosshead chamber. when thepressure in the crosshead chamber exceeds thepressure setting of the tail-shaft spigot safetyvalves, the safety valves open. The oil then flowsinto the return oil passage, completing the hubpurge circuit.

VALVE ROD ASSEMBLY

The valve rod assembly is the mechanical linkbetween the OD box and the hub servomotorregulating valve. It also provides the flow path

for hydraulic power oil from the OD box to theregulating valve. The rod is assembled fromfabricated sections of seamless steel tubing joinedtogether by oil-tight couplings. The aft end of therod is mechanically connected to the regulatingvalve pin. The forward end is mechanicallyconnected to the distance tube in the OD box. Thedistance tube is part of the OD box pistonassembly. This provides a positive drive forthe valve rod. Relative to the propeller shaft,the distance tube is keyed to axial slots inthe OD box extension shaft to prevent rotationof the rod.

Axial movement of the valve rod is actuatedand controlled by the OD box piston assembly.As the valve rod translates, it moves the regulatingvalve pin axially in the valve liner. The movementof the valve pin ports hydraulic power oil to eitherside of the servomotor piston. This in turn resultsin propeller blade pitch rotation. The amount ofaxial travel of the va1ve rod is equal to the travelof the hub servomotor piston.

OIL DISTRIBUTION BOX

The OD box has two main purposes: (1) Itprovides the actuation and control of theregulating valve rod, and (2) it directs HPhydraulic oil to and from the propeller shaftflow passages. It also provides the mountingfor the manifold block assembly, local pitchindicator, linear feedback potentiometer, andshaped readout potentiometer of the controlvalves.

The regulating valve rod is actuated andcontrolled by the OD box piston assembly, shownin figure 8-23. This assembly consists of a for-ward and an aft piston mechanically connectedto make a double-ended piston. The piston fitsbetween the forward and aft control oil chambersof the OD box. Not shown in figure 8-23 aremolythane polypak seals which are installed in thepiston heads and in the annular packing glandseparating the chambers. Each chamber has asingle port for normal supply and return ofcontrol oil. Each chamber also has a singleemergency port for connection of the emergencyhand pump.

Control oil pressure of 350 psig is ported toeither control oil chamber by the control valvemanifold assembly. It responds to either an

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Figure 8-23.—Oil distribution box.

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electrical or manual pitch change command.If the command is for pitch change ahead,control oil is ported to the forward controloil chamber; the aft control oil chamberport is open to return, causing the pistonassembly to move forward. This translatesthe valve rod forward, resulting in propellerpitch change in the ahead direction. As thepiston assembly moves forward, the oil inthe aft control oil chamber is displaced throughthe aft chamber port by the aft piston. If thecommand is for pitch change astern, control oilis ported to the aft control oil chamber and theaction is reversed. The oil flow directions areindicated in figure 8-23.

The piston assembly is mechanically connectedto the valve rod by a bearing assembly anddistance tube. The bearing assembly is necessaryfor the transfer of the axial forces since the pistonis stationary, while the distance tube and valverod rotate with the propeller shaft. The bearingassembly also absorbs the thrust load of the valverod.

If a failure of the normal pitch control systemoccurs, an emergency system is provided. Thecontrol valves and emergency pump assembliesare shown in figure 8-24. A hand-operatedhydraulic pump can be connected to theemergency ahead and astern control oil portslocated adjacent to the normal ports. A four-wayselector valve on the emergency pump is used todirect pump output pressure to the forward or aftcontrol oil chamber for the desired pitch. Alocking device on the OD box end cover enablesthe propeller to be locked in the emergency aheadposition for sustained operation. In the lockedposition, a machined shoulder on the lockingdevice mechanism within the OD box engages theforward piston and mechanically locks the pistonin posit ion.

A follow-up rod is connected to the forwardpiston and extends through a penetration in theend cover. Externally, the follow-up rod isconnected to a local pitch indicator and twosliding-contact potentiometers mounted on top ofthe OD box. The potentiometers provide feedbackand pitch readout signals to the electronic pitchcontrol system. The local pitch indicator is apointer which slides along a scale calibratedin feet of pitch. The indicator scale extends overthe end of the OD box and reads from 15 feetastern to 28 feet ahead. It has a separate notch

at the forwardmost end indicating EMERGAHEAD.

CONTROL VALVES MANIFOLDBLOCK ASSEMBLY

On the OD box is a manifold block assembly.This assembly houses the two four-way change-over valves, the electrohydraulic servo controlvalve, and the manual control valve. It isreferred to as the control valves manifold blockassembly and is shown in figure 8-24. Its functionis to direct the flow of control hydraulic oil fromthe HOPM to the control oil section of the ODbox. It responds to an electrical or manual inputto control propeller pitch.

The two four-way changeover valves areused to select the operating mode. Each valve hasa selector handle with a pointer and a dial. Thedials are labeled MAN-OFF-AUTO. Both selectorhandles must be placed in the same mode forproper operation of the system. The OFF positionof the changeover valves is used only when theyare being operated with the emergency pitchpositioner.

In the AUTO (automatic) mode, the electro-hydraulic control oil servo valve directs thecontrol oil flow to the OD box. It responds to anelectrical signal from the electronic pitch controlunit located in each engine room.

In the MAN (manual) mode, the manualcontrol valve directs the control oil flow to theOD box in response to movement of the valvelever. The manual control valve has a controlhandle with three positions labeled AHEAD,OFF, and ASTERN. The control handle is spring-loaded in the OFF (center) position. Movementof the control handle in the desired direction, thatis, AHEAD or ASTERN, will result in a pitchchange. It is held in that position until the desiredpitch has been attained. When the desired pitchhas been reached, the handle is released. It returnsto the OFF position by the spring force, and thepropeller pitch holds at the new position.

HYDRAULIC OIL POWER SYSTEM

The purpose of the hydraulic oil power systemis to supply both HP hydraulic oil for propellerblade actuation and control oil for propeller pitchcontrol. A schematic of the hydraulic oil system

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Figure 8-24.—Control valves and emergency pump assemblies.

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used is shown in figure 8-25. The system consistsof an HOPM; a gear-driven attached or gear hydraulicpump; the manifold block assembly of the con-trol valve; and associated piping, valves, andfittings.

Hydraulic Oil Power Module

The HOPM is located adjacent to the MRG.It contains the motor-driven, screw-type electric or motor operatedhydraulic oil pump, a suction strainer, twoduplex fil ters, and a pressure controla s s e m b l y . I t a l s o c o n t a i n s a d u p l e xcontrol oil filter, two gauge panel assemblies withassociated instrumentation, a manual bypassvalve, and interconnecting piping and fittings.

The motor-driven electric or motor operated hydraulic pump drawsoil from the sump tank through a foot valve anda suction strainer. The foot valve allows oil flowin one direction only, thus preventing thebackflow of oil from the pump to the tank whenthe pump is shut down. The suction strainer isa telltale, bypassing type of strainer. An indicatoron the strainer indicates the degree of clogging.If the indicator is ignored and the degree ofclogging becomes extensive, the oil is internallybypassed around the strainer element. Thehydraulic pump delivers 160 gpm at up to 1,000psig. From the pump, the oil flows through aduplex f i l te r to the pressure cont ro lassembly. An air bleed valve, located between thepump and the filter, automatically purgesentrapped air from the system. It also aids initialstart-up and priming of the pump.

You can start or stop the HOPM electric pumpmotor from the CCS or from a local motorcontroller located adjacent to the HOPM. Themotor controller has a two-position transferswitch with the positions labeled LOCAL andREMOTE. The LOCAL position allows theelectric pump motor to be operated from the localcontroller and at the same time inhibits operationfrom the consoles. The REMOTE position allowsthe electric pump motor to be operated from theconsoles, while inhibiting operation from the localcontroller.

The pressure control assembly (seen in fig.8-25) regulates the HP (power) oil and control oilthat is supplied by the HOPM. The assemblyconsists of a pilot-operated unloading valve andcheck valve together in one housing, a motor-driven pump check valve, a relief and sequencevalve together in another housing, a pressure-reducing valve, and an auxiliary relief salve.During normal operation, both the electric or motor operated HOPM

pump and the attached or gear hydraulic pump arerunning. The electric or motor operated pump normally supplies thehydraulic oil flow, while the attached or gear pump flowis returned to the sump tank by the unloadingvalve. The check valve prevents the electric or motor operated pumpdischarge from entering the attached or gear pump. If theelectric or motor operated pump fails or the pressure drops belowminimum, the pilot-operated unloading valvedirects the flow from the attached or gear pump to theelectric or motor operated flow path. In this mode, discharge from theattached or gear pump is prevented from entering the electric or motor operatedpump by the electric or motor operated pump check valve.

The hydraulic oil flow next enters the reliefand sequence valves. An unloading valve is usedto maintain system pressure. The sequence valveacts to maintain a minimum hydraulic oil pressureof 350 psig at the inlet of the control oil pressure-reducing valve. High-pressure oil for the propellerhub leaves the sequence valve at a pressure of 200to 600 psig. If the oil pressure exceeds themaximum limit of 1,000 psig, the relief valveopens and excess pressure is bled off to the sumptank. Oil from the pressure-reducing valve(control oil) flows at reduced pressure (10 gpmat 350 psig nominal). It flows through aduplex filter to the control oil section of the ODbox. If the control oil pressure exceeds 600 psig,the auxiliary relief valve opens and the excesspressure is bled off to the sump tank.

A manually operated bypass valve is locatedin a line between the sequence valve discharge andthe return line to the sump tank. This valve isnormally closed during operation.

A spring-loaded check valve is located in thehub oil return line between the OD box and theHOPM. It maintains the return oil pressurebetween 28 and 35 psig during system operation.It assures a positive pressure on the return lineduring system shutdown. At this time, the CRPhead tank provides the only source of return linepressure.

The attached or gear hydraulic pump is a verticallymounted, screw-type pump identical to the motor-driven electric or motor operated pump. It is driven by the MRG. Thepump draws oil from the sump tank through afoot valve and suction strainer identical to thosein the electric or motor operated pump system. The discharge from theattached or gear pump flows through a duplexfilter, located in the HOPM, to the pilot-operatedunloading and check valve.

Oil Distribution

As discussed earlier, there are three oil systemscommon to all CPP/CRP systems. They are the

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Figure 8-25.—CRP hydraulic system schematic.

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control oil system, the power oil system, and thereturn oil system. In the following section, we willdescribe these systems.

CONTROL OIL.—Control oil from theHOPM enters the OD box through the controlvalves manifold block assembly. Figure 8-26shows the control oil line entering the controlvalves manifold block assembly and dividing withtwo separate flow paths. One leads to theelectrohydraulic servo valve and the other leadsto the manual control valve. The outflow lines ofthese valves meet at two changeover valves. Onechangeover valve allows oil to pass in or out ofthe astern OD box piston chamber through asingle line. The other changeover valve allows flowinto or out of the forward OD box piston chamberthrough a single line. Each changeover valvedetermines which control valve (servo or manual)outflow is going to pass through to the OD box.With the changeover valves in the MANUALposition, only the control oil passing through themanual control valve can pass through thechangeover valves to the OD box. The AUTOposition passes only the control oil from theelectrohydraulic servo valve. When the change-over valves are in the OFF position, no oil canflow in or out of the OD box except through theemergency hand pump connections.

During normal control oil flow, with thechangeover valves in the AUTO position, theservo control valve is opened by signals from theelectronic pitch control system to increase pitchin the astern direction. Control oil flows throughthe servo control valve and the astern changeovervalve to the astern pitch connection on thebottom side of the OD box. Entry of oil into theastern piston chamber causes the piston assemblyto move aft, thus translating the valve rod for apitch change astern. As the piston assembly movesaft, the oil in the forward piston chamber ispushed out through the forward pitch connectionlocated on the top side of the OD box. This returncontrol oil flows out through the forwardchangeover valve to the servo control valve. Itthen passes to the return oil line that leads backto the sump.

If ahead pitch is ordered, the servo controlvalve switches the flow path. This causes oil toenter the forward pitch connection on the OD boxrather than the astern pitch connection. Oilreturns from the astern pitch connection, and theflow is reversed from the situation described inthe previous paragraph. The manual control valvedirects the control oil flow in the same way as

described previously. The only difference is thatthe valve is operated manually through a lever,as opposed to the servo control valve which isoperated electrically through a solenoid.

The emergency pitch connections are usedwhen control oil or HP oil are not available fromthe HOPM. As seen in figure 8-23, the emergencyconnections supply oil to the OD box piston inthe same manner as the normal connections. Thedifference is that the control oil must be suppliedfrom a special hand pump and a much higherpressure is required.

POWER OIL.—High-pressure hydraulic oilfrom the HOPM enters the OD box through aflange connection on the bottom aft section (fig.8-23). The flange passes the oil to an annularchannel in the stationary HP seal assembly. TheHP seal ring, which seals the top of the annularchannel, is attached to the OD box shaft. As theOD box shaft turns, the HP seal ring rotates inthe top of the channel. Holes drilled through theHP seal ring and continuing through the OD boxshaft conduct the HP oil from the annularchannel in the HP seal assembly to an annularchamber formed between the OD box shaft andthe distance tube. This chamber directs the oilslightly aft to where it enters the regulating valverod through two drilled passages. The HP oil thencontinues through the valve rod to the propellerhub.

RETURN OIL.—Return oil from the hub,which is called LP oil, flows forward through thepassage between the outside surface of the valverod and the inside surface of the propeller shaft.The return oil enters the OD box through sixpassages drilled in the OD box shaft between thepropulsion shaft and the OD box shaft extension.The six passages direct the oil to a relatively largeannular return oil chamber. Any leakage past theHP seal also enters the return oil chamber. Returnoil is discharged from the return oil chamber backto the CRP sump through a flange connection.This flange connection is located just forward ofthe HP oil inlet connection.

The CRP head tank connects to the return oilchamber through a flange located on the top aftsection of the OD box. This location places thehead tank above the OD box. The overflow lineallows the 65-gallon tank to hold 40 gallons beforepassing oil back to the sump. The purpose of thehead tank is to maintain a static head pressureon the oil in the propeller hub when the hydraulicsystem is shut down. This prevents seawater from

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Figure 8-26.—Control valve manifold oil flow.

leaking past the blade seals and into the hydraulicsystem. Hydraulic oil continually fills the headtank from the return oil chamber and flows backto the sump through the overflow line when theHOPM is providing HP oil. This head tankcirculation is caused by the return check valve inthe return oil line. When the HOPM is operating,the check valve maintains approximately 28 to 35psig in the return oil chamber. Since 28 to 35 psigis greater than the head pressure caused by thetank height, return oil continuously fills the tank,and it overflows back to the sump. When HP oil

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to the propeller is shut off, the check valveprevents the head tank from draining back intothe sump. The head tank then provides sufficientpressure to prevent seawater entry through thehub seals since it is 4 to 6 feet above the ship’swaterline.

ELECTRONIC PITCHCONTROL SYSTEM

The pitch of the CRP propeller is establishedelectrically through the electrohydraulic pitch

control systems located in the engine room.The system has two basic parts or groupsof components. One part of the system is theCRP electronics enclosure mounted on verticalstanchions near the free-standing electronicsenclosure (FSEE) in each engine room. The otherbasic group is the components mounted on theOD box. This group consists of the control oilservo valve and two slide-type potentiometers.Figure 8-27 shows the relationship between thetwo basic parts of the system. Although thesystems for each shaft are identical, they are alsoindependent. The propeller pitch on the starboardshaft can be set to the same value or to a differentvalue than the port shaft pitch. The settingdepends on what is ordered through the consoles.

Electronic pitch control begins with the pitchcommand signal generated by the console. Thecommand signal is sent to the CRP electronicsenclosure. It then causes a servo valve positionsignal to be sent to the control oil servo valve onthe OD box. The servo valve is driven off centerand allows control oil to enter the OD box pistonchamber, thus moving the control piston andvalve rod assembly. The direction in which theservo valve opens is determined by the command

signal polarity. The follow-up rod is attached tothe forward end of the piston and extends throughthe OD box end cover. It moves with the valverod assembly and positions a pointer on the ODbox pitch indicator. The follow-up rod alsopositions the sliding contacts on the two OD boxpotentiometers. The shaped potentiometer pro-vides the signal source for electronic display ofthe actual blade pitch. The linear potentiometerprovides the feedback signal that cancels the pitchcommand signal. It also provides the feedbacksignal that allows the control oil servo valve toclose when the pitch ordered by the pitch com-mand signal has been reached. The CRP electronics enclosure providesthe supply voltage for both potentiometers.Besides providing control and potentiometervoltages, the CRP electronics enclosure receives the potentiometerfeedback and position signals. It also supports alocal five-point pitch level display and a localdigital output monitor display intended primarilyto aid in testing and calibrating the electroniccircuitry.

Control Oil Servo Valve

The control oil servo valve located on the ODbox is an electrohydraulic valve. It uses an

Figure 8-27.—Electrical and hydraulic signal flow between CRP system components.

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electric solenoid and internal hydraulic pres-sure to ac tua te the va lve componentthat controls oil flow through the valve.The function of the control oil servo valveis to pass control oil to the ahead or asternside of the OD box piston. The OD boxpiston, in turn, changes the pitch of the propellerblades.

The control oil servo valve is electricallyactuated by the servo valve controller circuitcard contained in the CRP electronics en-closure. Two conductors carry the servo signalfrom the electronics enclosure to a terminalbox mounted near the OD box in eachengine room. At the terminal box, the twoconductors from the electronics enclosureare doubled. This provides a four-conductorcable that carries the signal from the term-inal box to the servo valve. The four con-ductors connect to the two coils of theservo valve solenoid in a parallel configu-ration. Each coil has a dc resistance of1,000 ohms. If an ohmmeter is used tomeasure the total resistance of the solenoid,it should read 500 ohms when measured fromthe two conductors that run between theelectronics enclosure and the terminal box.The absolute value of the maximum voltagethat should appear on the servo valve so-lenoid is approximately 7.2 volts.

The solenoid discussed in this manual ismore correctly called a torque motor. Thecoils are wrapped around a small plate calledthe armature. When a dc voltage is appliedto the coils, the armature flexes in reactionto the current flow within the magneticfield. The magnetic field is established bypermanent magnets mounted in the torquemotor housing. Direction of armature move-ment depends on the dc voltage polarity.The magnitude of armature movement dependson the strength of the dc voltage. The dcvoltage can be from 0 volts to 7.2 voltsof either positive or negative polarity. Asmall pilot valve is attached to the arm-ature. When the armature is moved, it un-balances the internal oil pressure and causesthe valve to rotate and open the aheador the astern valve port. With zero volt-age applied to the coils, the pilot valveis centered by internal oil pressure so thatthe valve component also becomes centeredby the oil pressure. Oil is then unable to

flow in or out of the servo valve portsleading to the OD box piston chambers.Therefore, pitch remains unchanged.

The servo valve has four ports bored in themounting base. These ports are for incomingcontrol oil, outflow to the astern pitch side of theOD box piston, outflow to the ahead pitch sideof the OD box piston, and oil return to thehydraulic oil sump. These ports line up withpassages drilled in the control valves manifoldblock assembly on which the servo valve ismounted.

OD Box-Mounted Potentiometers

The linear feedback and shaped poten-tiometers are mounted side by side on thetop of the OD box. Each potentiometeris housed in a rectangular box about 18inches long, 1 l/2 inches wide, and 1 l/2inches tall. A shaft which moves the slidingcontact extends out of the forward end ofeach potentiometer box. A Y-shaped yokeconnects the ends of the potentiometer shaftsto the end of the follow-up rod that extendsout the forward end of the OD box. Thefollow-up rod provides a mechanical position-ing of the potentiometer shafts that correspondsto actual propeller pitch positions. The follow-up rod also positions a mechanical pointeralong a calibrated scale mounted betweenthe potentiometers. Slots in the potentiometermounting feet provide for longitudinal positionadjustments when the zero pitch feedbackand readout signals are calibrated.

LINEAR POTENTIOMETER.—The linearpotentiometer provides the pitch feedback signalto the servo valve controller card in the CRPelectronics enclosure. The resistance element isapproximately 10 kilohms from end to end. Theterm linear means that the resistance is evenlydistributed along the potentiometer body andthat the voltage picked up by the slidingcontact is proportional to its position along thepotentiometer body.

SHAPED POTENTIOMETER.—The shapedpotentiometer generates the pitch readoutsignal. The pitch readout signal is used todisplay pitch on the five-point indicator atthe PLCC and on the digital demand display

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at the ECSS operating station. Theresistance across the shaped potentiometerfrom end to end is about 15 kilohms. Theword shaped is used to describe this poten-tiometer because the resistance is not evenlydistributed along the potentiometer body.Slightly more resistance (ohms per inch ofpotentiometer) is at the ends than in themiddle. This nonlinear resistance distributionis necessary to compensate for the increasedsensitivity of the propeller pitch to the valverod positioning at the extreme ahead andastern pitch settings. As maximum aheador maximum astern pitch is approached, alesser change in valve rod position is neededto obtain a certain pitch change. More changeis needed if the blades are closer to zeropitch. This is caused by the decreased anglebetween the valve rod and the lever armformed by the center post of the bladeand the sliding block crankpin. So, an in-crease in potentiometer resistance is necessaryat both ends to reflect the same pitch changeon the electronic readout devices with lessvalve rod change (equal to follow-up rodchange).

PRAIRIE AIR SYSTEM

Prairie air is emitted from small holes drilledin the leading edges of the CRP propeller blades.The discussion presented here deals only with thePA flow in the OD box, along the propulsionshaft, and from the hub assembly to the propellerblade leading edges.

PA is piped from the PA cooler to therotoseal on the forward end of the ODbox. The rotoseal passes air from the sta-tionary external piping to the rotating PAtube in the center of the OD box pistonassembly. The PA tube consists of sectionsof seamless, stainless steel tubing connectedby welded couplings containing O-ring seals.The tube runs aft through the centers ofthe OD box piston assembly, the bearingsupport, the distance tube, and the valverod to the propeller hub assembly. The tubeis held in the center of the valve rod bywelded-on guides that support the tube awayfrom the valve rod inner wall. At the aftend of the hub, the PA tube terminateswith a check valve in the hub cone end

cover. The check valve discharges PA intodrilled passages in the hub cone end cover.The end cover passages connect with passagesin the hub cone and hub body to directthe PA to the center post of each blade.The PA flows from the center post througha bushing connection to a drilled passagein the root of the blade. The drilled passagedirects the air to a machined channel underthe leading edge. From the channel, thePA discharges into the water through smallorifices drilled in the blade edge.

Two check valves in the PA tubing pre-vent entry of seawater into the system whenthe PA is not being used. The primarycheck valve is installed in the hub coneend cover as mentioned previously. It limitsseawater backflow to the propeller bladesand hub cone. A backup check valve islocated in the OD box at the connectionbetween the PA tubing and the rotoseal.Should the primary check valve fail, thebackup check valve will prevent seawaterfrom passing through the rotoseal and fillingthe shell of the PA cooler.

PROPULSION SHAFTING SYSTEM

The propulsion shafting system consists of thepropulsion shafts, the line shaft bearings, the strutbearings, the stern tube bearings, the bulkheadseals, and the stern tube seals. The followingdescription of the propulsion shafting equipmentis representative of types found aboard the variousgas turbine ships. Consult the manufacturers’technical manuals for specific informationconcerning your ship.

SHAFTING

The shaft transmits propulsion torque to thepropeller and thrust to the Kingsbury thrustbearing. In addition, the shaft is designed toaccommodate the CRP propeller hydraulics andPA tubing. The PA tubing runs through thepropulsion shaft at the center line. The center lineis surrounded by the propeller valve control rod,as seen in figure 8-28. High-pressure hydraulic oilfrom the HOPM is supplied to the propeller hubthrough the interior of the valve rod. Oil returnsfrom the hub to the sump tank in the annular

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Figure 8-28.—Cross-sectional view of propulsion shaft.

space between the valve rod and the insidediameter of the propulsion shaft. It then flowsthrough the OD box to the hydraulic oil sumptank.

SHAFT BEARINGS

The shaft bearings are used to support theshaft. Bearings are mounted in the stern tube andpropeller strut and are seawater lubricated. Theremaining bearings are self-aligning, oil-lubricatedjournal bearings commonly called line shaft bear-ings (LSBs). Each LSB is a self-containedassembly with its own oil reservoir that contains2190 TEP oil.

An oil disc clamped to the shaft is used in eachbearing to deliver oil to the upper bearing andjournal surfaces. As the disc rotates, it picks upoil from the bearing reservoir and carries it to theoil scraper on the upper shell. The scraper removesoil from the disc and directs it to the upper bear-ing lining. A clear sight hole cover on the bear-ing housing allows visual confirmation of the oillevel and oil disc operation.

All bearing pedestals have an oil level rod andan oil reservoir thermometer for checking oil leveland temperature. An RTD is installed in the lowerbearing shell of each oil-lubricated bearing. The

RTDs provide for remote readout of each bear-ing’s temperature on the digital demand displays.

Strut Bearings

Each propeller shaft extending aft of the sterntubes is supported by a strut. Each strut containsa seawater-lubricated bearing. The strut bearingsare cooled by constant immersion in seawater andare not monitored by the ECSS.

Stern Tube Bearings

The stern tube bearings are in constantcontact with the seawater surrounding the sterntubes. The clean seawater that passes through thestern tube seals from the ship’s firemain systemor seawater service system also flows through thestern tube bearings. They are identical to the strutbearings in design. However, the strut bearingsare roughly 5-inches larger in diameter and twiceas long as the stern tube bearings. The stern tubebearings are not monitored.

PROPULSION SHAFT SEALS

The propulsion shaft penetrates the hull andvarious compartment bulkheads. At these pointsit is necessary to install some type of sealingarrangement to prevent progressive floodingbetween compartments. Where the shaftpenetrates a compartment bulkhead, they arenaturally called bulkhead seals. Where the shaftpenetrates the hull, they are called stern tube seals.

Bulkhead Seals

The bulkhead seals will maintain watertightintegrity of the bulkhead penetrated by shaftingwhen either side of the bulkhead is flooded. Theseseals are self-aligned with the shaft. They willaccommodate ±1.75 inches perpendicular move-ment of the shaft with longitudinal movement of0.040 inches because of thrust bearing clearanceand 0.50 inch because of thermal changes.

The seal assembly consists of a basering bolted to the bulkhead, two sealingdiscs, right-hand and left-hand sealing rings,and a cover. The two sealing rings are identical,except that one is a mirror image of theother. They are formed by three plain andthree slotted carbon segments. Six pressure ring

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segments (fig. 8-29) are placed around the twocarbon sealing rings, and the assembly is held inplace by two garter springs. The two sealing discsare installed with one on either side of the seal-ing rings. Attached to each sealing disc are threestops that mate with the slotted carbon segments.These stops ensure that the sealing ring assemblydoes not rotate with the shaft.

When the compartment on one side of the sealis flooded, water pressure on the carbon sealingring on the wet side creates a gap between thecarbon ring and sealing disc. This gap allowswater to enter the seal housing to force the othersealing ring against the shaft and sealing disc.Pressure on the far side sealing ring is directlyproportional to the head of water in the floodedcompartment plus the contact pressure of the

of water pressure, so flooding is confined to theone compartment only.

Stern Tube Seals

The purpose of the stern tube seals is to pre-vent seawater from entering the ship at the pointwhere the shaft or shafts penetrate the hull.

Different types of stern tube seals are installedaboard ships, but they all serve the same purpose.We will use the MX9 model installed on theDD-963 class ships as an example of a stern tubeseal.

The MX9 seal (fig. 8-30) is a radial face,hydraulically balanced seal located on the inboardside of the ship’s stern tube. Primary sealingoccurs between the stationary face insert and therotating seat in a plane perpendicular to the center

garter spring. Sealing action is a direct function line of the shaft.

Figure 8-30.—MX9 stern tube seal.

8-47

Face to seal contact pressure is maintained bythe force of the springs, which is developed in thebellows seal assembly, and by the hydraulic forcesinduced onto the components of the seals by theseawater being sealed. This combination of springand hydraulic forces maintains a consistent facecontact pressure and consistent seal leakagedespite seal wear.

The bellows assembly is the flexible memberof the seal allowing the seal to accommodateshaft or hull movements caused by thermaldifferences, thrust loads, vibration, and bearingtolerances.

The seawater flush system is designed to havea seawater flush of 15 gpm and 20 psi. A vent lineis also provided to allow passage of any airtrapped in the stern tube and seal housing to theatmosphere.

Two backup sealing systems have beenincorporated into the stern tube seal; the inflatableseal and a conventional stuffing box.

The inflatable seal is an elastomer channelincorporated into the mounting ring, When theinflatable seal is subject to air pressure, it expandsand seals the radial gap between the stern shaftand the seal housing. This allows the seal to be

Figure 8-31.—Stern tube piping diagram (typical).

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inspected or repaired while the ship is still in thewater.

The second sealing system is the stuffing boxthat has been incorporated into the mounting ring.By first inflating the seal and then removing theseal drive clamp ring, seal, face insert, facecarrier, and bellows assembly, you can installpacking rings and packing. You can then bolt agland follower to the mounting ring and adjustit to provide enough leakage for lubrication. Youcan rotate the shaft but must keep it underobservation.

Figure 8-31 is a typical diagram of piping tothe stern tube seal. Consult your ship’s EOSS foryour ship’s piping and valve arrangement andpressure settings.

The inflatable seal can be inflated either byship’s LP air or a compressed air bottle.

SUMMARY

In this chapter, we have provided you with anoverview of the power train aboard gas turbineships. We have described how the power from theGTE is transmitted to the MRG through theshafting to the CRP propeller. This propellersystem provides a means for rapid and efficientship’s acceleration and backing down. Knowledgeof how the MRG system, CRP system, PAsystem, and the shafting system are constructedand their operation will be helpful to you in main-taining and operating this vital equipment.

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CHAPTER 9

ENGINEERING ELECTRICAL EQUIPMENT

Many of the tasks assigned to you involve theoperation and maintenance of components of the60-Hz power distribution system. This mayinvolve work on lighting systems, power panels,motor controllers, motors, receptacle circuits, anddistribution switchboards (SWBDs). Most of the60-Hz electrical equipment you work with is foundin the MERs and the CCS. Gas turbine ships alsohave Electrician’s Mates assigned. They arenormally responsible for the electrical equipmentfound outside the main machinery spaces.

The information in this chapter provides youwith basic knowledge of the equipment, pro-cedures, terminology, and special precautionsused with 60-Hz equipment. After reading thischapter, you should be able to identify 60-Hzequipment. You should be able to identify thedifferent types of generators, motors, SWBDs,circuit breakers (CBs), motor controllers, anduninterruptible power supplies (UPSs) found ongas turbine ships. Also, you should be able todescribe the numbering system used to identifyelectrical equipment and cables.

The material presented in this chapter is basicin nature and explains the principles of operationof engineering electrical equipment. By studyingthis material, you should be able to relate thisinformation to the specific equipment found onyour ship.

GENERATORS AND MOTORS

Electricity is the most efficient and cheapestmeans of distributing energy aboard ships. It isthe primary method used to distribute energyaboard ship. If electricity were not used, alternatemethods, such as the distribution of hot gases androtating energy, would require massive insulatedducting, heat exchangers, many complex gear-boxes, and shafts. All these systems would makecontrol of this energy very difficult.

Generators are the primary means of con-verting mechanical energy to electrical energy.Motors are the primary means of convertingelectrical energy into mechanical energy.

GENERATORS

The two types of ac generators are

rotating field—stationary armature, and

rotating armature—stationary field.

Only the rotating field—stationary armature—is used on gas turbine ships. The size of thegenerators found on gas turbine ships varies. TheFFG-7 class ships have 1000-kW ship’s servicediesel generators (SSDGs). The DD-963 class shipshave 2000-kW SSGTGs. The CG-47, DDG-51,and DDG-993 class ships have 2500-kW SSGTGs.

The two major components of the rotatingfield-stationary armature-are the stator and therotor (fig. 9-1). The stator (armature) is the

Figure 9-1.—Generator stator and rotor.

9-1

stationary part of the generator enclosedin the generator housing and is the set ofwindings in which voltage is produced. Itsupplies power to the ship’s loads (via aSWBD). The rotor (field) is the rotating partand is driven by the prime mover, either adiesel engine or a GTE. Direct current isinduced into the rotor by the voltage regulatorcircuit to create the rotating magnetic field.The design speed of the generator determinesthe number of magnetic poles required on therotor and the frequency output.

Generators on gas turbine ships rotate at1800 rpm. The rotors of these generators arethe salient pole type and have four magneticpoles, two positive and two negative. Fieldexcitation is provided by either slip rings andbrushes on a brush-type generator, or asilicon rectifier assembly on the newer brush-less generators. The slip rings or the siliconrectifier assembly allows a path of flow forthe current from the voltage regulator to therotor. The magnetic field allows for thetransmission of energy from the rotor to thestator. Varying the current to the rotor allows youto control the generator output voltage and thereactive load (amperage).

Brushless ac generators are used in thefleet for ship’s service and emergency power.Figure 9-2 compares the brush-type and brush-less ac generators. In the brush-type acgenerator (fig. 9-2, view A), the current istransferred from the rotating member of themachine to the stationary member and viceversa by the commutator, slip rings, andbrushes. Brushless ac generators, on theother hand (fig. 9-2, view B), have a siliconrectifier assembly that replaces this coupling.This development is simple, compact, free ofsparking, and greatly reduces the maintenanceof generators. Silicon rectifiers are mountedon the rotating shaft to furnish dc to theac generator rotor field. In the brush-typeac generator, the commutator serves as arectifier to perform this function. Feedbackfrom the 3-phase power output through avoltage regulator control (not shown) furnishesthe correct amount of excitation to the exciterfield for ac generator voltage control.

Generator frequency and resistive (kW) loadbalance (for paralleled generators) are controlled

by the prime mover speed, which in turn iscontrolled by the installed governor. By adjustingthe governor setting on two generators in parallel,an operator can equalize the active kW load andkeep the frequency at 60 Hz.

Chapter 4 of this TRAMAN providedinformation to help you understand the electricalprinciples concerning electric power. Refer toNEETS, modules 1, 2, and 5, for additionalinformation.

MOTORS

You will be called upon to perform preventivemaintenance on 60-Hz ac motors. The size ofthese motors varies. They can be as large as a lubeoil pump motor or as small as a cooling fanmotor in an electronics enclosure. Regardless oftheir size, motor operation is theoretically thesame.

The two major types of induction motors youmay encounter are the polyphase (3-phase) andthe single-phase. The induction motor getsits name from the fact that electromagneticinduction takes place between the stator and therotor under operating conditions. Most of thelarge motors found on gas turbine ships arepolyphase. Smaller motors, like those used forelectronics enclosure cooling fans, are normallysingle-phase.

Polyphase Motors

The driving torque of ac motors comesfrom the reaction of current-carrying con-ductors in a magnetic field. In inductionmotors, the rotor currents are supplied byelectromagnetic induction. The 3-phase statorwindings (coils) receive power from the externalsource via a controller. They produce a con-tinuously rotating magnetic field at constantspeed (synchronous), regardless of the loadon the motor. The rotor is not connectedelectrically to the power supply. The revolvingmagnetic field produced by the stator cutsthe conductors of the rotor. This induces avoltage in the conductors and causes currentto flow. Hence, motor torque is developedby the interaction of the rotor’s magnetic

9-2

Figure 9-2.—An ac generator. A. Brush type. B. Brushless.

9-3

field and the stator’s revolving magnetic field.Figure 9-3 shows the parts of a typical polyphase(3-phase) induction motor.

Many other components of the 3-phase motorare used for cooling, support, balancing, andprotection of the motor. Ball bearings support therotor and provide for low friction loss. Balancingdisks are used to balance the rotor. Rotor fansare normally provided to cool the motor with air

from the air inlets in the end bells. Verticallymounted motors usually have a dripproof coverover the top to prevent moisture from enteringthe housing.

Single-phase motors

Single-phase motors operate on a single-phasepower supply. These motors are used extensively

Figure 9-3.—Typical 3-phase induction motor.

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in fractional horsepower sizes in commercial anddomestic applications. The advantages of usingsingle-phase motors in small sizes are that theyare less expensive to manufacture than othertypes, and they eliminate the need for 3-phase aclines. Single-phase motors are used in electronicequipment, fans, refrigerators, portable drills,grinders, and so forth.

A single-phase induction motor with only oneset of stator windings and a cage rotor is similarto the 3-phase induction motor with a cage rotor.The single-phase motor has no revolving magneticfield at start; therefore, no starting torque.However, the rotor can be brought up to speedby special design of the stator winding. Then theinduced currents in the rotor will cooperate withthe stator currents to produce a revolving field.This causes the rotor to continue to run in the startdirection.

The identification of single-phase motors isdetermined by the different methods startingtorque is provided. These methods are split-phase,capacitor, or universal.

SPLIT-PHASE MOTOR.—The split-phasemotor (fig. 9-4) has a stator composed of slottedlaminations. The stator has an auxiliary (starting)winding and a running (main) winding (fig. 9-4,view A). The axes of these two windings aredisplaced by an angle of 90 electrical degrees. Thestarting winding has fewer turns and smaller wirethan the running winding; hence, the startingwinding has higher resistance and less reactance.The main winding occupies the lower half of theslots. The starting winding occupies the upper half(fig. 9-4, view B). The two windings are connectedin parallel across the single-phase line thatsupplies the motor. The motor gets its name fromthe action of the stator during the starting period.

At start, these two windings produce amagnetic revolving field. This rotating fieldrotates around the stator at synchronous speed.As it moves around the stator, it cuts across therotor conductors and induces a voltage in them.This voltage is maximum in the area of highestfield intensity. Therefore, it is in phase with thestator field. The rotor current lags the rotorvoltage at start by an angle that approaches 90degrees because of the high rotor reactance. Theinteraction of the rotor currents and the statorfield causes the rotor to accelerate in the directionin which the stator field is rotating. Duringacceleration, the rotor voltage, current, andreactance are reduced. The rotor currents comecloser to an inphase relation with the stator field.

Figure 9-4.— Split-phase motor. A. Circuit diagram. B. Wind-ing configuration. C. Centrifugal switch.

9-5

When the rotor reaches about 75 percent ofsynchronous speed, a centrifugally operatedswitch (fig. 9-4, view C) disconnects the startingwinding from the line supply. The motor con-tinues to run on the main winding alone. Thenthe rotating field is maintained by the interactionof the rotor and stator electromagnetic forces.

CAPACITOR MOTOR.—The capacitormotor is single-phase and has a capacitor in serieswith the starting winding. An external view isshown in figure 9-5 with the capacitor located ontop of the motor. The capacitor produces a greaterphase displacement of currents in the starting andrunning windings than is produced in the split-phase motor. The starting winding in the capacitormotor has many more turns of larger wire thanthe split-phase motor. The starting winding is con-nected in series with the capacitor. The startingwinding current is displaced about 90 degreesfrom the running winding current. The axes of thetwo windings are also displaced by an angle of90 degrees. Therefore, a higher starting torque isproduced than that in the split-phase motor. Thestarting torque of the capacitor motor may be asmuch as 350 percent of the full-load torque.

UNIVERSAL MOTOR.—A universal mot orcan be operated on either dc or single-phase ac.Aboard Navy ships, they are used extensively forportable tools. The motor is constructed with a

Figure 9-5.—Capacitor motor.

main field connected in series with an armature.The armature is similar in construction to any dcmotor. When electric power is applied, themagnetic force created by the fields reacts withthe magnetic field in the armature to causerotation.

60-HERTZ DISTRIBUTIONSYSTEM COMPONENTS

After the 450-volt , 60-Hz power is generatedby an SSDG or an SSGTG, the power must bedistributed throughout the ship. Distribution isaccomplished by the use of SWBDs, CBs, powerpanels, automatic bus transfer (ABT) switches,manual bus transfer (MBT) switches, transform-ers, and cables.

Although each class ship has items peculiaronly to that class, operation of switchboards isfairly common for all 60-Hz systems. You mustalways use EOSS when operating the 60-Hzswitchboards. You will undergo extensive ship-board training using PQS to qualify as anelectrical watch stander.

SWITCHBOARDS AND PANELS

A switchgear group is a single section or severalsections of switchboard mounted near each other.Switchgear groups are connected together withcabling and disconnect links. They are enclosedin a sheet-steel enclosure from which only handles,knobs, and meters protrude. No live contacts areexternally exposed on any switchboard on a gasturbine ship. The sections are identified with anumber and letter designation. When discussingthe entire switchgear group, the designation is itsnumber followed by the abbreviation SG. Eachsection is identified by its number followed by Sor SA for the control section and SA or SB forthe distribution sections. On the FFG-7 class ship,each SWBD has two sections. The SA is the con-trol section; the SB is used for distributionbreakers. On the larger gas turbine ships, the SGis composed of three sections. The control sectionis the S section; the distribution breakers are onthe SA and SB sections.

Example:

FFG-7—No. 1 SSDG feeds the 1SG groupcomposed of 1SA and 1SB.

DDG, DD, CG—No. 2 SSGTG feeds the 2SGgroup composed of 2S, 2SA, and 2SB.

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The control section controls the generator’soutput. The distribution section distributes powerto the different loads on the ship.

Switchboard bus bars (fig. 9-6) are heavy,rugged copper or aluminum bars. They distributethe power within the SWBD. They are usedbecause they can carry the large current loadsfound in the SWBD.

Current between SWBD sections is also veryhigh. Large cables are used to connect thesesections. Since there are no CBs between sections,you have to use some device to isolate a sectionafter a casualty. Disconnect links are used for thispurpose. These devices are connected to the bus

bars and interconnecting cable ends and can carrythe bus current. One disconnect link is used oneach phase.

WARNING

NEVER OPEN OR CLOSE DISCON-NECT LINKS ON AN ENERGIZEDSWITCHBOARD.

Control Section

The control section contains controls andinstruments required to control the generator’s

BUS BARSDISCONNECT LINKS

27.353Figure 9-6.—Rear view of a switchboard showing bus bars.

9-7

Figure 9-7.—Control section, front view.

9-8

output. Figure 9-7 shows the control section automatic paralleling device (APD). On theof an FFG-7 class ship SWBD. The upper two back side of the control section you will find fusespanels contain meters and switches. The middle for the control circuits and meter circuits. Othertwo panels and one of the lower panels devices on the back side are the CBs for thecontain the generator CB and the bus tie seawater circulating pump and the casualty powerCBs. The other lower section contains the terminal (fig. 9-8).

Figure 9-8.—Control section, back view.

9-9

Figure 9-9.—Distribution section.

9-10

Distribution Section

The distribution section contains all the CBsthrough which the power is distributed to thevarious power panels or individual equipment.Figure 9-9 shows an example of the distributionsection.

Power Panels

Power panels are located throughout the shipto distribute power to the ship’s loads. You canfind different numbers of circuits in a panel,up to as many as 16. Vital power panels arefed via ABTs. This allows the panel to be fedfrom either of two sources. Loads on powerpanels can include motors, heaters, electronics,and distribution panels. Some of the distributionpanels are fed by a transformer bank, which isused to reduce the voltage from 450 volts to 115volts for lighting distribution panels. The lighting

panels may feed fuse boxes that supply smallerloads or receptacles.

Shore Power

A means of supplying electrical power to aship from an external source is known as shorepower. The installation of shore power requiresa shore-power station, plugs, and connectingcables. The number of cables required will differwith each class of ship.

A shore-power station (fig. 9-10, view A) islocated at or near a suitable weather decklocation, to which portable cables can be attachedfrom shore or a ship alongside. The same stationcan be used to supply power from the ship to aship alongside. The shore-power station has areceptacle assembly arranged as shown in figure9-10, view B.

A shore-power plug is installed on theend of shore-power cables for ease of making the

Figure 9-10.—Shore-power station and receptacle assembly.

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OVERCURRENT TRIP

shore-power connection. Figure 9-11 shows ashore-power plug. Personnel injury and equip-ment damage can be avoided when shore-powercables and fittings are inspected before shore-power connections are made.

FLEXIBLE CONNECTIONARC QUENCERS

Circuit Breakers

The purposes of a CB are to provide switchingoperation, circuit protection, and circuit isolation.

Air CBs are used in SWBDs, switchgeargroups, and distribution panels. The typesinstalled on naval ships are ACB, AQB, AQB-A,AQB-LF, NQB-A, ALB, and NLB. They arecalled air CBs because the main current-carryingcontacts interrupt in air.

Circuit breakers are available in manually orelectrically operated types. Some types may beoperated both ways, while others are restricted toone mode. They may or may not be provided withprotective functions. The differences and uses ofthe various types of CBs are described in thefollowing sections.

ACB.—The ACB type of CB may be eithermanual (local) closing or electrical (remote)closing. It has an open metallic frame construc-tion mounted on a drawout mechanism and isnormally used where heavy load and high short-circuit currents are available. Figure 9-12 showsthe external view of a type ACB circuit breaker.

Figure 9-12.—Type ACB circuit breaker.

Figure 9-11.—Shore-power plug.

9-12

Type ACB circuit breakers are used toconnect ship’s service generators to the powerdistribution system and bus ties.

When a CB is used to connect ship’s servicegenerators to the SWBD, they must have a reversepower relay installed. The reverse-power relay ismounted on a panel close to the CB. Otherautomatic controls may be located at remotepoints to give maximum protection to the circuit.

Circuit breakers designed for high currentshave a double-contact arrangement. The completecontact assembly consists of the main bridgingcontacts and the arcing contacts. Current-carryingcontacts are constructed of high-conductivity, arc-resisting, silver-alloy material, which is bonded tothe contact surface for durability and longer wear.

Each contact assembly has a means of holdingthe arcing to a minimum and of extinguishing the

arc as soon as possible. The arc control sectioncontains an arc chute. The contacts are soarranged that when the circuit is closed, thearcing contacts close first. Proper pressure ismaintained by springs to be sure the arc contactsclose first. The main contacts then close.

When the circuit opens, the main contactsopen first. The current is then flowing throughthe arc contacts, which prevents burning of themain contacts. When the arc contacts open, theypass under the front of the arc runner. This causesa magnetic field to be set up, which blows the arcup into the arc chute and quickly extinguishes thearc.

AQB.—Type AQB circuit breakers, such asthe AQB-250 shown in figure 9-13, view A, aremounted in supporting and enclosing housings of

Figure 9-13.—AQB-A250 circuit breaker. A. Front view. B. With cover removed. C. Shunt trip.

9-13

insulating material and have direct-actingautomatic tripping devices. They are used toprotect single-load circuits and feeder circuitscoming from a load center or distribution panel.

The outside dimensions of these breakers arethe same for both the two-pole dc CB and three-pole ac CB. They are designed for front or rearconnections. They may be mounted so they canbe removed from the front without removing theCB cover.

The frame size of the CB is designated by the250. In a 250-ampere frame size CB, the current-carrying parts of the breaker have a continuousrating of 250 amperes. Trip units for this breaker(fig. 9-13, view B) are available with currentratings of 125, 150, 175, 225, and 250 amperes.

The trip unit houses the electrical trippingmechanisms, the thermal element for tripping theCB on overload conditions, and the instantaneoustrip for tripping on short-circuit conditions.

The automatic trip devices of the AQB-A250circuit breaker are trip-free. In other words, theCB cannot be held closed by the operating handleif an overload exists. When the CB has trippeddue to overload or short circuit, the handle restsapproximately in a center position. To reclose theCB after automatic tripping, move the handle tothe extreme OFF position. This resets the latch

in the operating mechanism. Then move thehandle to the ON position.

The AQB-A250 circuit breaker may haveauxiliary switches or shunt trip (for remotetripping) attachments. Figure 9-13, view C, showsa shunt trip. The instantaneous trip setting of theAQB-A250 trip units may be adjusted by theinstantaneous trip adjusting wheels. These tripadjusting wheels can be adjusted to five positions,LO-2-3-4-HI. The trip unit label will list theinstantaneous trip value obtainable for eachmarked position. The settings must be the sameon each pole of the CB.

Terminal mounting block assemblies (fig.9-14) consist of terminal studs in terminalmounting blocks of insulating material. Theterminals of the CB have slip-type connectors,which engage the terminal studs as shown in figure9-14. Two mounting blocks are required for eachCB. This method of connecting a CB to a bus orcircuit is known as a back-connected CB. SomeAQB circuit breakers have solderless connectorsattached to their terminals for front-connections.

AQB-LF.—The AQB-LF250 circuit breaker(fig. 9-15, view A) combines the AQB circuitbreaker features with a current-limiting fuse unit,which interrupts the circuit when the current ismore than the interrupting rating of the breaker.

Figure 9-14.—AQB-A250 circuit breaker, rear view, with terminal mounting block.

9-14

9-15

Constructed as one compact unit, the AQB-LFcircuit breaker includes the current-limiting fuses(fig. 9-15, view B) as integral parts of the CB. Thetrip units and trip features in the AQB-LF circuitbreaker are the same as those in the AQB-A250circuit breakers.

The current-limiting fuse unit is designed totrip the breaker and open all poles if any current-limiting fuse (fig. 9-15, view C) blows. After afuse blows, the CB cannot be reclosed until theblown fuse is replaced. Any attempt to removethe fuse unit causes the CB to automatically goto the trip position.

The AQB-LF250 circuit breaker is mechan-ically interchangeable with the AQB-A250 circuitbreaker, except a larger cutout is required in theSWBD front panel to accommodate the fuse unitof the AQB-LF250.

The AQB-LF250 circuit breaker is a 250-ampere frame size. However, the CB has aninterrupting rate of 100,000 amperes at 500 voltsac, 60 Hz. The AQB-A250 circuit breaker has aninterrupting rating of 20,000 amperes at 500 voltsac, 60 Hz.

While the AQB-A250 circuit breaker can beeither front or back connected, the AQB-LF250is designed only for back (drawout type) connec-tion. It uses the same type of slip connectors andterminal studs as shown in figure 9-14.

NQB.—The NQB-A250 circuit breaker issimilar to the AQB-A250 circuit breaker, exceptthe NQB-A250 has no automatic tripping devices.This CB is used for circuit isolation and manualtransfer applications. The NQB-A250 is a250-ampere frame size. The current-carrying partsof the breaker are capable of carrying 250amperes. Technically, this CB is simply a250-ampere on-and-off switch.

ALB.—The ALB circuit breakers aredesignated low-voltage, automatic CBs. Thecontinuous duty rating ranges from 5 to 200amperes at 120 volts ac or dc. The breaker isprovided with a molded enclosure, drawout typeof connectors, and nonremoveable and non-adjustable thermal/magnetic trip elements.

This CB is a quick-make, quick-break type.After the CB trips, before resetting it, you mustplace the handle in the OFF position.

NLB.—The NLB circuit breakers are just likethe ALB circuit breakers, except that they haveno automatic tripping device. They are used onlyas on-off switches.

POWER DISTRIBUTIONCOMPONENTS

Many components of the 60-Hz distributionsystem are located throughout the ship to

Figure 9-16.—Typical 60-Hz vital circuit using the ABT.

9-16

provide isolation, switching, and distribution.These components include ABTs, MBTs, andtransformers. This equipment routes power fromthe SWBD to the loads. Some equipment protectsthe distribution system from casualties in theloads; other equipment transforms and switchesthe power to send it to the load. In the followingsections, we will discuss these components and theprotective features they add to the entire distribu-tion system.

Automatic Bus Transfers

An ABT is an electromechanical device that

normal to alternate if the normal source fails.Power is fed through an ABT to most of the vitalequipment on board ship. The normal andalternate sources of power for an ABT are fedfrom two independent sources of power. They arenever fed by two sources from the same SWBD.Figure 9-16 is a line diagram of a typical vitalcircuit from the SWBD to the load. Lighting invital areas are also fed via ABTs.

The model A-2 ABT unit is designed to handlesmall loads. It operates on 120-volt, 60-Hz circuits. Thisunit (fig. 9-17) may be used on single- or 3-phasecircuits. For purposes of explanation, the 3-phase

automatically switches power sources from unit will be discussed.

Figure 9-17.—A pictorial view of an ABT.

9-17

The ABT is designed to transfer automaticallyfrom normal to alternate supply. It does this upona decrease in voltage across any two of its threephases. Upon restoration of the voltage, the unit isadjusted to retransfer to the normal source ofsupply.

The ABT unit shown in figure 9-17 is equippedfor manual operation. To manually operate theABT, place the control disconnect switch in themanual position and operate the manual switch.When in AUTO, test the automatic operation ofthe ABT by turning the spring-loaded test switchto the test position.

You must be careful when testing the ABTunits to ensure they do not include in their loadvital and sensitive electronic circuitry that will beadversely affected by the loss and almost instantreturn of power. You must ensure all other groupsare adequately informed of power supply systemtests to be performed.

Manual Bus Transfers

The MBTs are devices located within powerpanels that enable manual shifting from normalto alternate power. The MBTs are used on loadsthat are vital but do not require automaticrecovery upon loss of power. An example of acircuit with an MBT would be engine-roomventilation power. While it is desirable to haveventilation all the time, its loss for a short timewould not adversely affect plant operation. Whentime permits, an operator can switch the MBT andrestart the vent fans.

Most MBTs are built into the power panelsthey serve. They are constructed of two CBs withsome type of mechanical safety interlock.Indicator lights are also provided to show thesources of power available. The CBs are typeNQB or CBs without trip elements.

The mechanical interlock is usually a movablebar that prevents closing both CBs at the sametime. NEVER TAMPER WITH OR BYPASSTHE INTERLOCK ON AN MBT. If both sourcebreakers are closed at the same time, severedamage could result. If you are operating theelectric plant in split-plant mode, you could endup paralleling the ship’s load across cables andbreakers rated much lower than the bus tiecapacity.

The following is the correct procedure for youto use when shifting an MBT from normal toalternate power.

1. Be sure the alternate power indicator lampis on, showing that power is available.

2. Open the normal power CB.3. Shift the interlock to prevent closure of the

normal power breaker and enable closureof the alternate power breaker.

4. Close the alternate power CB.

NOTE: If you are shifting MBTs while poweris available on both sources, you should obtainpermission from the EOOW before starting theprocedure. Failure to do so could cause loss ofequipment that is on the line.

Transformers

A transformer is a device that has no movingparts. It transfers energy from one circuit toanother by electromagnetic induction. The energyis always transferred without a change infrequency. Usually there are changes in voltageand current. A step-up transformer receiveselectrical energy at one voltage and delivers it ata higher voltage. Conversely, a step-downtransformer receives energy at one voltage anddelivers it at a lower voltage. Transformers requirelittle care and maintenance because of theirsimple, rugged, and durable construction. Theefficiency of transformers is high. Because ofthis, transformers are responsible for the moreextensive use of ac than dc. The conventionalconstant-potential transformer operates with theprimary connected across a constant-potentialsource. It provides a secondary voltage that issubstantially constant from no load to full load.

Various types of small single-phase trans-formers are used in electrical equipment. In manyinstallations, transformers are used on SWBDsto step down the voltage for indicating lights.Low-voltage transformers are included in somemotor control panels to supply control circuits orto operate overload relays.

Instrument transformers include potential, orvoltage, transformers and current transformers(CTs). Instrument transformers are commonlyused with ac instruments when high voltages orlarge currents are to be measured.

The power-supply transformer used inelectronic circuits is a single-phase, constant-potential transformer. It has one or moresecondary windings, or a single secondary withseveral tap connections. These transformers havea low volt-ampere capacity. They are less efficientthan large constant-potential power transformers.

The typical transformer: has two windingsinsulated electrically from each other. Thesewindings are wound around a common magneticcore made of laminated sheet steel. The principal

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parts are (1) the core, which provides a circuit oflow reluctance for the magnetic flux; (2) theprimary winding, which receives the energy fromthe ac source; (3) the secondary winding, whichreceives the energy by mutual induction from theprimary and delivers it to the load; and (4) theenclosure.

When a transformer is used to step up the volt-age, the low-voltage winding is the primary. Con-versely, when a transformer is used to step downthe voltage, the high-voltage winding is the pri-mary. The primary is always connected to thesource of the power; the secondary is always con-nected to the load. It is common practice to referto the windings as the primary and secondaryrather than the high-voltage and low-voltage wind-ings. For more information on the constructionand installation of transformers, refer to the Elec-trician’s Mate, NAVEDTRA 12164.

POWER PANELS ANDCABLE MARKINGS

Some method must be used to locate powerpanels and the equipment that is fed. Also, switch-boards must have markings on the breakers toidentify what circuits or equipment are fed. TheNavy uses a standard system to identify thelocation and source of power for all switchboards,panels, and loads. This system uses thedeck/frame/side location that identifies othershipboard components. The system is also usedon cables to identify their power source.

The first part of the designation you seeidentifies the switchboard or load center thatsupplies the power. This could be numbers or aletter/number combination. The following is anexample of some markings you may find and whatthe first number means.

1SB-4P-2-216-2-C

From #1SWBD B section

41-4P-216-C

From loadcenter 41

3SA-4P-42

From #3SWBD A section

The second designation will tell you the voltagepotential and the use of the power. The mostcommon voltages used are 115 volts, designatedby a number 1, and 450 volts, designated bynumber 4. The number is actually the range thevoltage falls into, such as follows:

DESIGNATOR VOLTAGE RANGE

1 100 to 199

2 200 to 299

3 300 to 399

4 400 to 499

The letter part of the designation shows the useof the power. The most common ones are asfollows:

DESIGNATOR

K

C

EL

L

CP

P

WP

FEEDER

Control, power plant, and ship

Interior communications

Emergency lighting

Lighting

Casualty power

Ship’s service power

Weapon’s power

Other letters and symbols are used with thesebasic letters to form the complete cable designa-tion. This gives the cable’s source, service, anddesignation. Typical markings for power systemcables from a generator to a load and themeanings of the symbols are as follows:

1. Generator cables: 2SG-4P-2S

2SG—Fed from ship’s service (SS)generator No. 2

4P—450-volt power cable

2S—Supplying SS switchgear group No. 2

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2.

3.

4.

5.

6.

7.

Bus feeder: 2S-4P-31

2S—Fed from SS switchgear group No. 2

4P—450-volt power cable

31—Supplying load center SWBD No. 31

Feeder: 31-4P-(3-125-2)

31—Fed from load center SWBD No. 31

4P—450-volt power cable

(3-125-2)—Supplying power distributionpanel located on third deck, frame 125,port side

Main: (3-125-2)-4P-C

(3-125-2)—Fed from power distributionpanel located on third deck, frame 125,port side

4P—450-volt power cable

C—Indicates this is the third cable from thepanel, fed by breaker C

Submain: (3-125-2)-1P-C1

(3-125-2)—Fed from power distributionpanel located on third deck, frame 125,port side

1P—120-volt power cable

C1—Indicates first cable fed (through atransformer) by the main

Branch: (3-125-2)-1P-C1B

(3-125-2)—Fed from power distributionpanel located on third deck,port side

1P—120-volt power cable

C1B—Indicates second cablesubmain

frame 125,

fed by the

Subbranch: (3-125-2)-1P-C1B2

(3-125-2)—Fed from power distributionpanel located on third deck, frame 125,port side

1P—120-volt power cable

C1B2—Indicates second cable fed by thebranch

MOTOR CONTROLLERS

Motor controllers function to start a motor,to stop it, or to increase or decrease the speed ofa two-speed motor. There are many differenttypes of controllers. In this chapter we will onlydiscuss the most common types used on gasturbine ships.

A MANUAL controller is operated directlythrough a mechanical system. The operator closesand opens the contacts that normally energize andde-energize the connected load.

In a MAGNETIC controller, the contacts areclosed and opened by electromechanical devices.The devices are operated by local or remote masterswitches (defined in the next section). Magneticcontrollers may be semiautomatic, automatic,or a combination of both. Normally, all thefunctions of a semiautomatic magnetic controllerare governed by one or more manual masterswitches; those of an automatic controller aregoverned by one or more automatic masterswitches. Automatic controllers must be energizedinitially by a manual master switch. A full andsemiautomatic controller can be operated eitheras an automatic or as a semiautomatic controller.

An ACROSS-THE-LINE controller throwsthe connected load directly across the main supplyline. The motor controller may be either a manualor magnetic type. The type depends on the ratedhorsepower of the motor. Most controllers foundon gas turbine ships are magnetic across-the-linecontrollers.

Types of Master Switches

A master switch is a device that controls theelectrical operation of a motor controller. Theycan be manually or automatically operated.Drum, selector, and pushbutton switches areexamples of manual master switches. Theautomatic switch functions through the effect ofa physical force, not an operator. Examples ofautomatic master switches include float, limit, orpressure switches.

Master switches may start a series of opera-tions when their contacts are closed or when theircontacts are opened. In a momentary contactmaster switch, the contact is closed (or opened)momentarily; it then returns to its originalcondition. In a maintaining contact master switch,the contact does not return to its original condi-tion after closing (or opening) until againoperated.

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Magnetic Across-the-Line Controllers

A typical across-the-line, 3-phase controller isshown in figure 9-18. Figure 9-19 shows the maincontactor assembly. All contactor assemblies aresimilar in appearance but vary in size. You startthe motor by pushing the START button. Thisaction completes the circuit that will energize themain contactor assembly, closing the maincontacts connecting the full-line voltage to themotor.

The motor will continue to run until thecontactor coil is de-energized. It can be de-energized by the STOP push button, failure ofthe line voltage, or tripping of the overload relay(OL).

Two-Speed Control

An ac induction motor for two-speedoperation may have a single winding or twoseparate windings, one for each speed. Pressingthe HS push button closes the HS contactorassembly, connecting the high-speed windings tothe full-line voltage. Pressing the LS push

Figure 9-18.—Across-the-line, 3-phase controller.

Figure 9-19.—Contactor assembly.

button closes the LS contactor assembly,connecting the low-speed windings to the full-linevoltage. The two main contactor assemblies aremechanically interlocked. This prevents both CBsfrom being closed at the same time. The speedcan be changed without stopping the motor. Thecontactor coil is de-energized and energized in thesame manner as the magnetic controller.

Low-Voltage Protection

With low-voltage protection (LVP), when thesupply voltage is reduced or lost, you must restartthe controller manually. The master switch isusually a momentary switch.

Low-Voltage Release

When the supply voltage is reduced or lostaltogether, a low-voltage release (LVR) controllerdisconnects the motor from the power supply. Itkeeps it disconnected until the supply voltagereturns to normal. Then it automatically restartsthe motor. This type of controller must beequipped with a maintaining master switch.

Low-Voltage Release Effect

Most small manual across-the-line controllershave a property known as low-voltage releaseeffect (LVRE). These controllers are switched onto start a motor. When voltage is lost, the motorstops. When voltage returns, since the switch isclosed, the motor will restart. Although not trulyan LVR controller, since it does restart the motor,it is known as an LVRE.

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Overload Relays

Nearly all shipboard motor controllers pro-vide overload protection when motor currentis excessive. This protection is provided byTHERMAL or MAGNETIC overload relays.Those relays disconnect the motors from theirpower supply. This prevents them from over-heating.

Overload relays in magnetic controllers havenormally closed contacts. The contacts are openedby a mechanical device that is tripped by anoverload current. Opening the overload relaycontacts breaks the circuit through the operatingcoil of the main contactor. This causes the maincontactor to open, cutting off the power to themotor. Overload relays in manual controllersoperate mechanically to trip the main contacts andallow them to open.

THERMAL OVERLOAD RELAYS.—Thethermal overload relay has a heat-sensitiveelement. It has an overload heater that isconnected in series with the motor load circuit.When the motor current is excessive, heat fromthe heater causes the heat-sensitive element toopen the overload relay contacts. This breaks thecircuit through the operating coil of the maincontactor. The motor is also disconnected fromthe power supply. Since it takes time for parts toheat, the thermal overload relay has an inherenttime delay. This permits the motor to domaximum work at any reasonable current. It doesthis only as long as the motor is not beingoverheated. When it is, the overload relaydisconnects the motor.

There are four types of thermal overloadrelays: solder pot, bimetal, single metal, andinduction. The heat-sensitive element of aSOLDER-POT type is a cylinder inside a hollowtube. The cylinder and tube are normally heldtogether by a film of solder. If an overloadoccurs, the heater melts the solder (this breaks thebond between the cylinder and tube). Then thetripping device of the relay is released. After therelay trips, the solder cools and solidifies. Youcan then reset the relay.

In the BIMETAL type, the heat-sensitiveelement is a strip or coil of two different metals.They are fused together along one side. Whenheated, the strip or coil deflects because one metalexpands more than the other. The deflectioncauses the overload relay contacts to open. Theheat-sensitive element of the SINGLE-METALtype is a tube around the heater. The tube

lengthens when heated and opens the overloadrelay contacts.

The heater in the INDUCTION type has a coilin the motor load circuit and a copper tubeinside the coil. The tube acts as the short-circuitedsecondary of a transformer. It is heated by thecurrent induced in it. The heat-sensitive elementis usually a bimetal strip or coil.

MAGNETIC OVERLOAD RELAYS.—Themagnetic overload relay has a coil connected inseries with the motor load circuit and a trippingarmature or plunger. When motor current exceedsthe tripping current, the armature opens theoverload relay contacts. This type of magneticoverload relay operates instantly when the motorcurrent exceeds the tripping current. Another typeof magnetic overload relay is delayed a short timewhen motor current exceeds tripping current. Thistype is essentially the same as the instantaneousrelay except for the time-delay device.

OVERLOAD RELAY RESETS.—After anoverload relay has operated to stop a motor, itmust be reset before the motor can be run againwith overload protection. Magnetic overloadrelays can be reset immediately after tripping.Thermal overload relays must be allowed to coola minute or longer before they can be reset. Thetype of overload reset is manual, automatic, orelectric.

The manual, or hand, reset is located in thecontroller enclosure that contains the overloadrelay. This reset usually has a hand-operated rod,lever, or button that returns the relay trippingmechanism to its original position.

The automatic type of reset, usually a spring-or gravity-operated device, resets the overloadrelay without the help of an operator. The electricreset is operated by an electromagnet controlledby a push button. This form is used when it isdesired to reset an overload relay from a remoteoperating point.

SHORT CIRCUIT PROTECTION.—Over-load relays and contactors are usually not designedto protect motors from currents greater thanabout six times the normal rated current of acmotors. Since short-circuited currents are muchhigher, protection against short circuits in motorcontrollers is obtained through other devices.Navy practice is to protect against these shortcircuits with CBs placed in the power supplysystem. In this way, both the controller and motorare protected. The cables connected to the

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controller are also protected. However, sometimesshort circuit protection is provided in thecontroller. This is done in cases where it is nototherwise provided by the power distributionsystem. Short circuit protection for controlcircuits is provided by fuses in the controllerenclosure.

UNINTERRUPTIBLEPOWER SUPPLY

Periodically a gas turbine ship experiences apartial or total loss of 60-Hz ship’s service powerto engineering equipment requiring a constantpower source. The equipment may be a controlconsole, a SWBD, or a GTE. Most controlconsoles cannot withstand an interruption of thepower that feeds them. The LM2500 will shutdown if power is removed from the fuel valvesolenoids. Therefore, these vital engineeringfunctions must be maintained during a powerinterruption.

To provide power for vital pieces of equipmentduring short-term operation, gas turbine ships aredesigned with battery backup systems. Thisbattery backup provides an alternate source ofpower upon failure of ship’s service power.Because these systems need an immediate standbysource of power, they must have a very rapidmethod of transferring the load to the backup.This is done by use of static (electronic) switching.The shift from failing 60-Hz power to the batterybackup is very rapid. It is an uninterruptedshift. Therefore, the battery backup system iscommonly known as an uninterruptible powersupply (UPS).

All propulsion electronics rely on 115/120-voltac as the input to their power supplies. The UPSbattery systems for these consoles must providepower in that range. Batteries are normally a low-voltage dc power source. This means severalbatteries must be placed in series to obtain theproper voltage levels. We will refer to this groupof batteries as a battery bank.

The UPS system is different on the FFG-7class ships and the twin-shaft gas turbine ships.The UPS used on the FFG-7 class ship is thenormal source of power for the propulsionelectronics. It does not employ the batteries allthe time, but the UPS equipment is the normal

source for console power. The DD-963,DDG-993, and CG-47 class ships use a slightlydifferent concept for supplying uninterruptedpower to consoles. On these ships the normalsupply of power is from the ship’s service 120-voltac, 60-Hz bus. Power is also fed to the electronicsfrom the 150-volt dc UPS battery bank. Allswitching for this system is done in the propulsionelectronics. These classes also have battery backupfor each SWBD and SSGTGs. The battery supplyis an uninterruptible system but is NOT commonlyreferred to as UPS.

LEAD-ACID STORAGE BATTERIES

Storage batteries provide the power source forthe UPS system. Periodic inspection of the storagebattery is essential in maintaining maximumefficiency and long life of the battery. Batteriesused for UPS systems are subjected to moderatelyheavy use. They require frequent charging by theUPS battery charger.

As a GSE/GSM, you will be required to main-tain these battery banks. All the batteries used inUPS systems are wet-cell types. Their maintenancerequirements are special. For more informationon battery construction and their principles ofoperation, refer to NEETS, module 1.

SUMMARY

In this chapter we have discussed the majorcomponents of an ac electrical system. Theseincluded generators and motors, 60-Hz distribu-tion system components, the UPS, and lead-acidstorage batteries. You must remember thatthere are many different types of systemsand components other than the ones we havediscussed. Also, you should not undertake workon electrical equipment without reference to theproper technical manual.

For additional information on the materialcovered in this chapter, refer to Naval Ships’Technical Manual, chapter 300, “Electrical PlantGeneral,” chapter 310, “Electrical PowerGenerators and Conversion Equipment,” andchapter 320, “Electrical Power DistributionSystem.”

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CHAPTER 10

ENGINEERING ELECTRICAL EQUIPMENTMAINTENANCE

This chapter was developed from the GSE3OCCSTDs. However, by reading this chapter, aGSM will also be able to understand some of themaintenance requirements of electrical equipment.

Upon completing this chapter, you should beable to describe the basic techniques of wirewrapping, the maintenance requirements andtroubleshooting techniques of electrical equip-ment, and the requirements of lead-acid storagebatteries.

WIRE WRAPPING

In chapter 3 you were shown some of the handtools used for wire wrapping (fig. 3-13). Inthis section we will discuss the principles andtechniques involved in wire wrapping.

The equipment that you would use the wire-wrap technique on has long square pins/posts atthe rear of the female connectors used for logiccard inserts. An example is the back-planes ofvarious consoles. These pins are long enough toallow one to three wires to be wrapped on themin separate wraps. (A wrap is defined here as aseries of turns of a single solid wire about a pin.)The female connectors are then interconnectedfrom pin to pin by a small, solid insulated wire.This insulated wire may or may not be colorcoded. Machine-wrapped assemblies usually donot contain color-coded wiring. Hand-wiredassemblies do contain color-coded wiring. (Color-coded wire is an advantage in hand-wiredassemblies, since each wire becomes moredistinctive and fewer errors are likely to result.)

WIRE-WRAP PRINCIPLES

The principle behind wire wraps is a simpleone. For proper conduction to occur between twometals, the oxide coating that has formed on both

surfaces must first be penetrated. As mentionedabove, the pins used in the wire wraps are squaredoff. They have corner edges that will penetratethe oxide coating of the wire when it is properlywound on the pin. The edges will also lose theiroxide coating when they penetrate the surface ofthe wire. The junction that is formed is strong,gastight (tight enough to seal out gases, inaddition to liquids), and resistive to corrosion.

WIRE-WRAP TECHNIQUES

The technique of wire wrapping is also fairlysimple. A special solid conductor insulated wireis required. The use of solid conductor wireensures that the coil will form tightly about thepin and remain that way without appreciable slip-page. The wire is a composition of a silver alloywith a copper coating. Silver offers an advantagein that its oxide is almost as conductive as themetal itself. Teflon or Meline is usually theinsulation used on the wire. Teflon offers anadvantage of very high temperature stability andease of cutting (for stripping by automaticmachinery). It also has the undesirable trait of theinsulation gradually receding away from any pointof continued pressure—a process described as“cold flow.” Teflon-insulated wire in contact witha pin may eventually result in an intermittent shortoccurring at that point. Meline withstandscontinued exposure to pressure much better thanTeflon. It is more resistive to cold flow, but doesnot have the very high temperature characteristicsof Teflon. Meline has become more widely usedbecause of the cold flow problem.

The first step in wire wrapping is for you todetermine the correct gauge of wire required toperform the job. Strip off enough insulation toallow the correct number of turns to be woundaround the pin. Then place the end of the wirein either a long shallow groove along the barrelof the wire-wrap tool, or insert it in the smaller

10-1

Figure 10-1.—Basic wire-wrap procedure.

10-2

hole at the end of the barrel (fig. 10-1, view A).The groove (or hole) for the wire is carefully sizedto provide the exact amount of tension needed toform a secure wrap. Ensure the insulation bottomsinto the wire funnel as shown in view B of figure10-1. This will allow you to wrap the correctamount (one to one and a half turns) of insulatedwire around the wrap pin. Anchor the wire bybending it into the notch in the sleeve (fig. 10-1,view C). The center hole at the end of the barrelis next slipped down over the pin (fig. 10-1, viewD). When the barrel is rotated about the pin, thewire will twist around the pin (fig. 10-1, view E).As the wire twists around the pin, the strippedportion of the wire that is being held in the groove(or in the other base hole) will be drawn downto twist and coil around the pin. The barrel ofthe wire-wrap tool rotates as a result of finger,hand, or motor action. The action depends uponthe tool’s design. The coiling action of the wireon the pin lifts the tool enough to continue thewire coil up the pin, as shown in views F and Gof figure 10-1. However, too much pressure onthe tool will cause the coils to “bunch,” oroverlap. If you are replacing a wire, carefully runthe wire to the next connection and perform thesame procedure on the opposite end. Be sure youallow enough excess wire for the wraps neededon the pin.

Before actually doing a wire wrap on theitem you are repairing, take time to practicethis procedure. Find a spare connector orspare pin similar to those you are repairing.Using the same materials that are requiredfor the actual job, practice a few times.Figure 10-2, view A, shows a good wire wrap.It has five to seven and a half snug turnsof wire. Place the insulation about the bottom-most one or two turns with no spacingbetween adjacent turns, no bunching as one turnattempts to cover another, and no observablenicks in the wire. The number of turns isdetermined by the wire gauge. Larger diameterwires and pins require fewer turns, and smallerdiameters mean more turns.

Figure 10-2.—Correct and incorrect wire wraps.

2. Overtension on wire—results in looseconnection (detected by turn overlapsand insufficient surface contact with thepin)

3. Insufficient number of turns (less thanfive)—poor contact (insufficient wire wasstripped first)

4. Insulation does not extend to pin—increased chances of shorts or wire breaks(too much wire was stripped)

The following list describes a variety of IN-CORRECT methods of wire wrapping. Some ofthese are visually identifiable in figure 10-2,view B.

5. Reuse of an uncoiled wrap—each re-use increases the likelihood of wirebreaks

1. Insufficient tension on wire—results in 6. Attempts to wrap by hand—insufficientloose connection (detected by open spaces and uneven tension results in poor con-between adjacent turns) tact

10-3

Wire wraps are normally removed with a wire-wrap removal tool (fig. 10-3). This prevents stressand possible damage to the wire-wrap pin.However, if you have to remove the wire by hand,unwrap the wire without applying stress to the pin.You can best accomplish this by gently uncoilingthe wire with a slight rotating movement over thepoint of the pin. Make sure that the manner inwhich the wire is removed does not cause move-ment of the pin itself (fig. 10-4). If a pin is bent,it will probably break when an effort is made tostraighten it. If a pin breaks, first ensure that thebroken length is not left in the wiring to causepossible shorts. Then take the necessary steps toinstall a new pin. Normally, inner wire wraps areplaced near the bottom of the pin to ensure that

Figure 10-3.—Wire-wrap removal with wire-wrap removaltool.

Figure 10-4.—Manual method of removing a wire wrap.

additional wraps can be added easily. If you haveto remove a lower wire wrap, first remove eachwrap above it. Do not remove a wire wrap by try-ing to pull it along its axis (see fig. 10-4).Remember, each wrap is easily identified becauseit is formed from the multiple turns of a singlesolid wire.

When removing a wire wrap from a pin, youmust be careful not to disturb other wraps on thesame or adjacent pins or to dislodge the pin. Thiswould cause poor continuity or an open circuit.

Advantages

Some of the advantages of wire wraps are asfollows:

1.

2.

3.

4.

5.

6.

Simplified technique for repairs (wires aremerely uncoiled to remove and replacedwith the proper simple tools)No solder spill (makes repairs possiblewithout removing components)No danger of components overheating asduring solderingMore in-equipment repairs and fasterrepair timesNo danger of burning personnel (as froma hot soldering iron)Durable electrical contact (as good as havebeen achieved with good soldering tech-nique, and superior to those connectionsmade with poor soldering technique)

Disadvantages

Some of the disadvantages of wire wraps areas follows:

1. Use of solid wire (increases the likelihoodof wire breakage)

2. Problems with insulation3. Unsuitable to subminiature assemblies4. Lack of a wire color code in machine-

wrapped assemblies5. The necessity of clipping off the wrapped

portion of the wire and stripping the insula-tion back to expose new wire in making thenext wrap. (If the wire is too short topermit this, it must be replaced. The reasonthe same portion of wire is not reused inthe new wrap is that this area will have beenweakened structurally by nicks from itsprevious use and will be weakened furtherif reused.)

10-4

A number of useful tools, and techniques forusing them, have been developed for doing wirewraps. We have discussed only some of them. Foran excellent source on wire-wrapping techniques,refer to MILSTD (military standard) 1130B,notice 2, 20 July 1983, Connections, Electrical,Solderless, Wrapped.

Use caution in working with wire-wrapassemblies. These assemblies look like a bed ofnails, and people have been injured by simply nottaking precautions. A number of injuries occurto the face when the technician attempts to geta good look at the assembly from the side. Thisexposes the eyes to a needless hazard. Usesufficient lighting to make out details, smallmirrors where possible, and wear safety gogglesif a firsthand view from this position is necessary.When inspecting/repairing the back-planes orareas of possible damage, remember that ac ordc voltages may still be present. Ensure propersafety precautions are followed for working withenergized equipment.

MOTORS AND GENERATORS

At the shipboard level, maintenance on motorsand generators is usually limited to cleaning, bear-ing repair, and brush maintenance. Major repairs,such as rewinding and balancing, are done atIMAs or shipyards.

CLEANING MOTORSAND GENERATORS

One of your most important jobs is to keepall electrical machinery clean. Dust, salt, dirt, andforeign matter (such as carbon, copper, or mica)tend to block ventilation ducts. This increasesresistance to the dissipation of heat and causeslocal or general overheating. If the particles forma conducting paste through the absorption ofmoisture or oil, the windings may become shortcircuited or grounded. Additionally, abrasiveparticles may puncture insulation; iron dust is veryharmful since the dust is agitated by magneticpulsations. Proper cleaning of motors andgenerators involves the use of wiping rags,suction, LP air, and solvents.

Wiping with a clean, lint-free, dry rag (suchas cheesecloth) removes loose dust or foreignparticles from accessible parts. When wiping, donot neglect the end windings, slip ring insulation,connecting leads, and terminals.

Suction is preferred to compressed air forremoving abrasive dust and particles frominaccessible parts. This is because it lessens thepossibility of damage to insulation. A vacuumcleaner is good for this purpose. If one is notavailable, a flexible tube attached to the suctionside of a portable blower makes a usable vacuumcleaner. Always exhaust the blower to a suitablesump or overboard. When possible, remove grit,iron dust, and copper particles only by suctionmethods.

Clean, dry, compressed air is effective inremoving dry, loose dust and foreign particles,particularly from inaccessible locations such asair vents in the armature. Use air pressure up to30 psi to blow out motors or generators of 50 hpor 50 kW or less; use pressure up to 75 psi to blowout higher-rated machines. Where air lines carryhigher pressure than is suitable, use a throttlingvalve to reduce the pressure. Always blow out anyaccumulation of water in the air line beforedirecting the airstream on the part or machine tobe cleaned.

CAUTION

Be very careful when using compressedair, particularly if abrasive particles arepresent because they may be driven into theinsulation and puncture it or be forcedbeneath insulating tapes. Use compressedair only after you have opened the equip-ment on both ends to allow the air and dustto escape. Using compressed air is of littlebenefit if the dust is not suitably removedfrom the equipment. The most suitablemethod of removing dirt-laden air is toplace a suction hose on the opposite endof the equipment where compressed air isbeing used.

Whenever possible, avoid the use of solventsfor cleaning electrical equipment. However, theiruse is necessary for removing grease and pastysubstances consisting of oil and carbon or dirt.Alcohol will injure most types of insulatingvarnishes, and it should not be used for cleaningelectrical equipment. Because of their hightoxicity, solvents containing gasoline, benzene,and carbon tetrachloride must NEVER be usedfor cleaning purposes.

Motors, generators, and other electrical equip-ment that have been wet with salt water shouldbe flushed out with fresh water and dried. Never

10-5

let the equipment dry before flushing with freshwater. For complete information on approvedsolvents and washing and drying procedures, referto NSTM, chapter 300.

BEARINGS

Bearings are designed to allow a rotatingarmature or rotor to turn freely within a motoror generator housing. Shaft bearings must beproperly maintained to reduce the heat caused byfriction.

The two common types of bearings found inmotors and generators are antifriction bearingsand friction bearings.

Antifriction Bearings

There are two types of antifriction bearings—ball and roller. Basically, both types consist oftwo hardened steel rings, hardened steel rollersor balls, and separators. The annular, ring-shapedball bearing is the type of roller bearing used mostextensively in the construction of electric motorsand generators used in the Navy. These bearingsare further divided into three types dependentupon the load it is designed to bear— (1) radial,(2) axial thrust, and (3) angular contact. Examplesof these three bearings are shown in figure 10-5.

The ball bearing on a rotating shaft of anelectric motor or generator may be subjected toa radial, thrust, and/or angular force. While everyball bearing is not subjected to all three forces,any combination of one or more may be founddepending on the equipment design. Radial loadsare the result of forces applied to the bearing

Figure 10-5.—Representative types of ball bearings.

perpendicular to the shaft. Thrust loads are theresult of forces applied to the bearing parallel tothe shaft. Angular loads are the result of acombination of radial and thrust loads. The loadcarried by the bearings in electric motors andgenerators is almost entirely due to the weight ofthe rotating element. For this reason, the methodof mounting the unit is a major factor in theselection of the type of bearing installed when theunit is constructed. In a vertically mounted unit,the thrust bearing is used, while the radial bear-ing is normally used in most horizontal units.

WEAR.—Normally, it is not necessary tomeasure the air gap on machines with ball bear-ings, because the construction of the machines en-sures proper bearing alignment. Additionally, ballbearing wear of sufficient magnitude as to bereadily detected by air-gap measurements wouldbe more than enough to cause unsatisfactoryoperation of the machine.

The easiest way of determining the extent ofwear in these bearings is to periodically feel thebearing housing while the machine is running todetect any signs of overheating or excessive vibra-tion and to listen to the bearing for the presenceof unusual noise.

Rapid heating of a bearing may be an indica-tion of danger. Bearing temperature that feelsuncomfortable to the touch could be a sign ofdangerous overheating, but not necessarily. Thebearing may be operating properly if it has takenan hour or more to reach that temperature, butserious trouble can be expected if a hightemperature is reached within the first 10 or 15minutes of operation.

The test for excessive vibration relies a greatextent on the experience of the person conductingthe test. The person should be thoroughly familiarwith the normal vibration of the machine to beable to detect, identify, and interpret correctly anyunusual vibrations. Vibration, like heat andsound, is easily telegraphed. A thorough searchis generally required to locate its source and todetermine its cause.

Ball bearings are inherently more noisy innormal operation than sleeve bearings. If you aretesting for the presence of abnormal bearing noise,keep this in mind. A common method for soundtesting is to place one end of a screwdriver againstthe bearing housing and the other end against theear. If a loud, irregular grinding, clicking, orscraping noise is heard, trouble is indicated. Asbefore, the degree of reliance in the results of this

10-6

test depends on the experience of the personconducting the test.

Vibration analysis equipment is also used totest conditions of motor bearings. Initial baselinesurveys are taken. Then periodic checks are madeby maintenance personnel. The periodic checksdetermine if the bearings are still in normal work-ing condition or if they are failing. Consult yourship’s PMS documentation for the method usedfor vibration analysis on your ship.

Checking the movement of a motor orgenerator shaft can also give an indication of theamount of bearing wear. Figure 10-6, view A,shows how to get a rough check of vertical move-ment. If the motor shaft has too much verticalmovement, it has worn bearings. Figure 10-6, viewB, shows how to get a rough check of generatorend-play movement. You can correct excessiveend-play, as described in the applicable technicalmanual, by adding bearing shims.

BEARING INSTALLATION.—There aretwo acceptable methods for installing bearings,the arbor press method and the heat method.

Arbor Press Method.—When available andadaptable, you can use an arbor press if you takeproper precautions. Place a pair of flat steelblocks under the inner ring or both rings of thebearing. Never place blocks under the outer ringonly. Then, line up the shaft vertically above thebearing. Place a soft pad between the shaft andpress ram. After making sure the shaft is startedstraight in the bearing, press the shaft into thebearing. Press until the bearing is flush againstthe shaft or housing shoulder. When pressing abearing onto a shaft, always apply pressure to theinner ring; when pressing a bearing into ahousing, always apply pressure to the outer ring.

Heat Method.—You can heat a bearing in anoven or furnace to expand the inner ring for

Figure 10-6.—Checking motor or generator shaft. A. Ver-tical movement. B. End-play movement.

assembly. This method ensures uniform heatingaround the bearing.

Heat the bearing in an IR oven or atemperature-controlled furnace at a temperaturenot to exceed 203° ± 10°F. Do not leave thebearing in the oven or furnace after the inner racehas expanded the desired amount. Prolongedheating could deteriorate the prelubricationgrease.

Additional methods of bearing installation areexplained in NSTM, chapter 244.

Friction Bearings

There are three types of friction bearings,RIGHT LINE, JOURNAL, and THRUST. In theRIGHT LINE type, the motion is parallel to theelements of a sliding surface. In the JOURNALtype, two machine parts rotate relative to eachother. In the THRUST type, any force acting inthe direction of the shaft axis is taken up. TheSS generators are equipped with journal bearings,commonly called SLEEVE bearings. The bearingsmay be made of bronze, babbitt, or steel-backedbabbitt. Preventive maintenance of sleeve bear-ings requires periodic inspections of bearing wearand lubrication.

WEAR.—You can obtain bearing wear on asleeve bearing by measuring the air gap at eachend of the machine. Use a machinist’s taperedfeeler gauge. Use a blade long enough to reachinto the air gap without removing the end bracketsof the machine. For ac machines, clean a spot onthe rotor and at least three or more spots at equalintervals around the circumference on the stator.Take the air gap measurement between the cleanedspot on the rotor and a cleaned spot on the stator.Turn the rotor to bring the cleaned spot of therotor in alignment with the cleaned spots on thestator. Compare these readings with the tolerancestated by the manufacturers’ instruction manuals.

TROUBLE ANALYSIS.—The earliest sign ofsleeve bearing malfunction normally is an increasein the operating temperature of the bearing. AnRTD is usually inserted in a bearing for visualindication of the bearing temperature at a remotelocation. Personnel operating the equipment canuse the inserted thermometer in the lube oildischarge line for local monitoring. Operatingpersonnel take temperature readings hourly onrunning machinery. Therefore, after checking thetemperature, they should make a follow-up checkby feeling the bearing housing whenever possible.

10-7

Operating personnel must thoroughly familiarizethemselves with the normal operating temperatureof each bearing. They have to recognize anysudden or sharp changes in bearing temperature.

Any unusual noise in operating machinerymay also indicate bearing malfunction. When astrange noise is heard in the vicinity of operatingmachinery, make a thorough inspection todetermine its cause. Excessive vibration willoccur in operating machinery with faulty bearings.Make inspections at frequent intervals to detectfaulty bearings as soon as possible.

BRUSHES

The brushes used in generators are one ormore plates of carbon bearing against a collectorring (slip ring). They provide a passage forelectrical current to an internal or external circuit.The brushes are held by brush holders mountedon studs or brackets attached to the brush-mounting ring, or yoke. The brush holder studs,or brackets, and brush-mounting ring comprisethe brush rigging. The brush rigging is insulatedfrom, but attached to, the frame or one end bellof the machine. Flexible leads (pigtails) connectthe brushes to the terminals of the externalcircuit. An adjustable spring is generally providedto maintain constant pressure of the brush on theslip ring. This is required to retain good contactbetween the brushes and slip rings withoutexcessive wear of the brushes.

Brushes are manufactured in different gradesto meet the requirements of the varied types ofservice. The resistance, ampere-carrying capacity,coefficient of friction, and hardness of the brushare set by the maximum allowable speed and loadof the machine.

Correct Brush Type

The correct grade of brush and correctbrush adjustment are necessary to avoid brushperformance trouble.

Use the grade of brush shown on the drawingor in the technical manual applicable to themachine. An exception to this is when Naval SeaSystems Command instructions issued after thedate of the drawing or technical manual stateotherwise. In such cases, follow the Naval SeaSystems Command instructions.

Brush Care

You should ensure that all brush shunts aresecurely connected to the brushes and the brush

holders. Brushes should move freely in theirholders. They should not be loose enough tovibrate in the holder. Before replacing a wornbrush with a new one, clean all dirt and otherforeign material from the brush holder.

Replace with new brushes, all brushes that

1.

2.

3.

4.

5.

are worn or chipped so they will not moveproperly in their holders;have damaged shunts, shunt connections,or hammer clips;have riveted connections or hammer clipsand are worn to within 1/8 inch of themetallic part;have tamped connections, are withouthammer clips, and are worn to one half orless of the original length of the brush; orhave spring-enclosed shunts and are wornto 40 percent or less of the original lengthof the brush (not including the brush head,which fits into one end of the spring).

Where adjustable brush springs are of thepositive gradient (torsion, tension, or compres-sion) type, adjust them as the brushes wear to keepthe brush pressure near constant. Springs of thecoiled-band, constant-pressure type and somesprings of the positive gradient type are notadjustable. On these you have to change springs.You should adjust brush pressure following theMRC, the manufacturer’s technical manual, orNSTM, chapter 300. To measure the pressure ofbrushes operating in box-type brush holders,insert one end of a strip of paper between thebrush and slip ring. Use a small brush tensiongauge (such as the 0- to 5-pound indicating scale)to exert a pull on the brush toward the brushholder axis as shown in figure 10-7. Note thereading of the gauge when the pull is just sufficientto release the strip of paper so it can be pulledout from between the brush and slip ring withoutoffering resistance. This reading divided by thecontact area may be considered to be the springoperating pressure.

DISASSEMBLY AND REASSEMBLYOF MOTORS AND GENERATORS

When you have to disassemble and reassemblea large motor or generator, follow the proceduresin the manufacturers’ technical manuals. Neverbe hasty or careless in disassembling a generatoror motor. Handle the delicate components withcare to prevent or create the need for additionaladjustment. Use the proper tools, and label the

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Figure 10-7.—Measuring brush tension.

parts as you dismantle them. Store them in anorderly arrangement in a safe place. Note thenecessary information so you will have no troublein reassembly.

Follow these simple steps when disassemblinga motor or generator. Make sure you mark theframe and mating end bells (fig. 10-8); use adifferent mark for each end. When separating theend bells from the frame, use a mallet or blockof wood with a hammer (fig. 10-9). Never prymating surfaces apart with a metal object suchas a screwdriver. Protect the windings, whennecessary, by inserting thin strips of waxed paperbetween the rotor and the stator when the rotoris not supported.

When removing bearings, you can use anarbor press if you take proper precautions. Placea pair of flat steel blocks under the inner ring orboth rings of the bearing. Never place blocksunder the outer ring only. You may use a gearpuller to remove a rotor bearing. However, becareful.

Clean the end bells with a brush and anapproved solvent. Check them for cracks, burrs,nicks, excessive paint, and dirt.

Figure 10-8.—Marking a motor frame and end bell.

Figure 10-9.—Parting end bells with a hammer and woodblock.

CIRCUIT BREAKERMAINTENANCE

The circuit breakers (CBs) require carefulinspection and cleaning following the MRC, the

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manufacturers’ technical manuals, or NSTM,chapter 300.

Before working on a CB, de-energize allcontrol circuits to which it is connected; theprocedures differ somewhat with the type ofmounting that is used. On drawout CBs, ensurethey are switched to the open position andremoved. When working on fixed-mounted CBs,open the disconnecting switches ahead of thebreakers. If disconnecting switches are notprovided for isolation, de-energize the supply busto the CB. Circuit breakers have different timedelay characteristics, such as short time, longtime, or instantaneous trip. The adjustments forselective tripping of most CBs are made and sealedat the factory. You should not normally makechanges to their trip settings, as these changes maycompletely disrupt their intended functions ofprotection. If improper tripping action occurs asthe result of a malfunction within the breaker, thesimplest means to correct the problem is to replacethe entire breaker.

After a CB cover has been removed, youshould check the interior components, suchas contacts, overcurrent tripping devices, con-nections, and moving mechanical parts.

Contacts are the metal parts especially selectedto resist deterioration and wear as a result ofarcing. The arcing occurs in a CB while itscontacts are opening and carrying current at thesame time. When firmly closed, the contacts mustnot arc.

Contact materials have been subjected toconstant research. The result is various products,ranging from pure carbon or copper to pure silver.Each is used alone or as alloys with othersubstances. Modern CBs have contacts made ofa silver alloy coated with silver, or silver mixedwith tungsten. The silver alloy is extremely hardand resists being filed. Such contacts made ofsilver alloy conduct current when discolored(blackened during arcing) with silver oxide. Theblackened condition, therefore, requires nofiling, polishing, or removal. However, severepitting or burning of a silver contact may requiresome filing with a fine file or with fine sandpaper,No. 00. Never use emery paper or emery cloth toremove raised places on surfaces that prevent fullsurface closure of the contact surfaces. Ifnecessary, wipe the contacts with a CLEAN clothmoistened with INHIBITED methyl chloroformsolvent. To remove all DEADLY and TOXICfumes of the solvent, provide VERY LIBERALventilation with exhaust fans or with portableblowers.

The function of arcing contacts is notnecessarily impaired by surface roughness.Remove very rough spots with a fine file. Replacearcing contacts when they have been burnedseverely and cannot be properly adjusted. Makea contact impression and check the spring pressurefollowing the manufacturer’s instructions. Ifinformation on the correct contact pressure is notavailable, check the contact pressure with that ofsimilar contacts that are functioning properly.When the force is less than the designed value,the contacts either require replacing because theyare worn down, or the contact springs should bereplaced. Always replace contacts in sets, notsingly, and replace contact screws at the sametime.

Clean all surfaces of the CB mechanism,particularly the insulation surfaces, with a drycloth or air hose. Before directing the air on thebreaker, be certain (1) the water is blown out ofthe hose, (2) the air is dry, and (3) the pressureis not over 30 psi. Check the pins, bearings,latches, and all contact and mechanism springsfor excessive wear or corrosion and evidence ofoverheating. Replace parts if necessary.

Slowly open and close CBs manually a fewtimes. Be certain trip shafts, toggle linkages,latches, and all other mechanical parts operatefreely and without binding. Be certain the arcingcontacts make-before and break-after the maincontacts. If you note poor alignment, slug-gishness, or other abnormal conditions, adjustfollowing the manufacturer’s instructions for theparticular CB.

Keep the sealing surfaces of CB contactor andrelay magnets clean and free from rust. Rust onthe sealing surface decreases the contact force.This may result in overheating of the contact tips.Loud humming or chattering will often warn ofthis condition. A light machine oil wiped sparinglyon the sealing surfaces of the contactor magnetwill aid in preventing rust.

Always use oil sparingly on CBs, contactors,motor controllers, relays, and other control equip-ment. Do not use it at all unless it is called forin the manufacturer’s instructions or unless oilholes are provided. If working surfaces or bear-ings show signs of rust, disassemble the device andcarefully clean the rusted surfaces. Wipe light oilon sparingly to prevent further rusting. Oil hasa tendency to accumulate dust and grit. This willcause improper operation of the device, mainlyif the device is delicately balanced.

Clean arc chutes with a stiff brush and a cloth.Replace broken or deeply burned arc chutes. Be

10-10

certain arc chutes are securely fastened. Be surethere is enough clearance to prevent interferencewhen the switch or contact is opened or closed.

Replace shunts and flexible connectors, whichare flexed by the motion of moving parts, whenworn, broken, or frayed.

Regularly test the CBs by testing them on howthey are intended to function. For manuallyoperated CBs, simply open and close the breakerto check the mechanical operation. To check themechanical operation and the control wiring, testelectrically operated CBs by the operating switchor control. Exercise care not to disrupt anyelectric power supply that is vital to the operationof the ship. Also, be careful not to endangerpersonnel by inadvertently starting motors andenergizing equipment under repair.

Before returning a CB to service, inspect allmechanical and electrical connections. Theseinclude mounting bolts and screws, drawoutdisconnect devices, and control wiring. Tightenwhere necessary. Give the breaker a final clean-ing with a cloth or compressed air. Operatemanually to be certain all moving parts functionfreely. Check the insulation resistance with aMegger before reinstalling the CB in the SWBD.

CONTROLLERTROUBLESHOOTING

Although the Navy maintains a policy ofpreventive maintenance, sometimes trouble isunavoidable. In general, when a controller failsto operate or signs of trouble (heat, smoke, orsmell of burning) occur, you can find the causeof the trouble by a simple examination using thesense of feel, sight, or smell. However, at othertimes, finding the trouble involves more detailedactions.

Troubles tend to gather around mechanicalmoving parts. Problems also occur whereelectrical systems are interrupted by the makingand breaking of contacts. Center your attentionin these areas.

When a motor-controller system has failed andpressing the START button will not start thesystem, press the overload relay reset pushbuttons. Then attempt to start the motor; if themotor operation is restored, no further checks arerequired. However, if you hear the controllercontacts close but the motor fails to start, checkthe motor circuit continuity. If the main contactsdon’t close, check the control circuit forcontinuity. In the following paragraphs, an

example of troubleshooting a motor-controllerelectrical system is given in a sequence of stepsthat may be used in locating a fault (fig. 10-10).We will analyze the power circuit and then thecontrol circuit.

POWER CIRCUIT ANALYSIS

When no visual signs of circuit failure can belocated and an electrical failure is indicated in thepower circuit, first check the line voltage and fuses(or CB), as shown in figure 10-10. Place thevoltmeter probes on the hot side of the line fusesas shown at position A. A line voltage readingtells you that your voltmeter is operational. Ittells you that you have voltage to the source sideof the line fuses. You may also checkbetween the other lines. To check the fuse in line 1(L1), place the voltmeter across the line fuse as

Figure 10-10.—Troubleshooting a 3-phase magneticcontroller.

10-11

shown at position B between L1-L2. A voltagereading shows a good fuse in L1. Likewise, checkthe other two fuses between L1-L3 and L2-L3.A no-voltage reading would show a faulty fuse.

If the line fuses check good and the maincontacts are closed, then check the voltagebetween terminals T1-T2, T2-T3, and T1-T3. Thecontroller is faulty if there are no voltmeterreadings on all three of the terminal pairs. Youwould then proceed to check the main contacts,overloads, and lead connections within thecontroller. However, if there is voltage at all threeterminals, the trouble is either in the motor or thelines leading to the motor.

CONTROL CIRCUIT ANALYSIS

Suppose the overload reset buttons have beenreset and the START switch closed. If the maincontacts do not close, check the control circuit.A testing procedure follows.

1. Check for voltage in the controller at L1,L2, and L3.

2. Place the voltmeter probes at points C andD (fig. 10-10). You should have a voltagereading when the STOP switch is closed.You should have a no-voltage reading whenthe STOP switch is open. The conditionswould indicate a good STOP switch andcontrol circuit fuse.

3. Next, check the voltage between points Cand E. The START switch is good if youget a no-voltage reading when the STARTswitch is open. The START switch is alsogood if you get a voltage reading when theSTART switch is closed.

4. Place the voltmeter probes at points C andF. A voltage reading with the STARTswitch closed would indicate a good OL1.It would also indicate one of the follow-ing components is open: OL3, the maincoil, the control fuse, or the connection toL3.

5. Place the voltmeter probes at points C andG. Close the START switch. A no-voltagereading locates the trouble in the controlcircuit to OL3.

A faulty auxiliary contact is indicated underthe following conditions: (1) The system operatesonly as long as the START switch is held in theON position; and (2) when the switch is released,the system will shut down.

When starting a 3-phase motor, if the motorfails to start and gives a loud hum, you shouldstop the motor by pushing the STOP switch.These symptoms usually mean that one of thephases to the motor is not energized. You canassume that the control circuit is good. This isbecause the main coil has operated and theauxiliary contacts are holding the main contactorclosed. Look for trouble in the power circuit (themain contacts, overload relays, cable, and motor).

LEAD-ACID STORAGE BATTERIES

Storage batteries provide the power source forthe UPS battery system. Periodic inspection ofthe storage battery is essential in maintainingmaximum efficiency and long life of the battery.Batteries used for UPS systems are subjected tomoderately heavy use. They require frequentcharging by the UPS battery charger or rectifier.

SPECIFIC GRAVITY

The ratio of the weight of a certain volumeof liquid to the weight of the same volume ofwater is called the specific gravity of the liquid.The specific gravity of pure water is 1.000.Sulfuric acid has a specific gravity of 1.830. Amixture of sulfuric acid and water is calledelectrolyte. The specific gravity of electrolyte willvary from 1.000 to 1.830.

As a storage battery discharges, the sulfuricacid is depleted. The electrolyte is graduallyconverted into water. This action is a guide indetermining the state of discharge of the lead-acidcell. The maximum specific gravity of electrolyteplaced in a lead-acid battery should be 1.350 orless. Generally, the specific gravity of theelectrolyte in standard storage batteries is adjustedbetween 1.210 and 1.220.

Measuring Specific Gravity

The specific gravity of the electrolyte ismeasured using a hydrometer, which wasdiscussed in chapter 3. Figure 3-40 shows ahydrometer. The hydrometer used with portablestorage batteries has a float with a scale from1.100 to 1.300. When taking a reading, ensure thatthe electrolyte in a cell is at the normal level. Ifthe level is below normal, you cannot drawenough fluid into the tube to cause the float torise. If the level is above normal,’ there is too muchwater. Then the electrolyte is weakened, and the

10-12

reading is too low. A hydrometer reading isinaccurate if you take it immediately after wateris added. This is because the water tends toremain at the top of the cell. When water is added,charge the battery for at least an hour. This willmix the electrolyte before the hydrometer readingis taken.

CAUTION

After use, flush hydrometers with freshwater. This prevents inaccurate readings.Do NOT use storage battery hydrometersfor any other purpose.

Correcting Specific Gravity

Temperature affects the specific gravity ofelectrolyte. When electrolyte is heated, it expandsand becomes less dense. Its specific gravity readingis lowered. On the other hand, when electrolyteis cooled, it contracts and becomes denser whencooled. Its specific gravity reading is raised. Inboth cases, the electrolyte may be from the samefully charged storage cell.

When measuring the specific gravity, you mustalso measure the temperature of the electrolyte.Most standard storage batteries use 80°F as thenormal temperature to which specific gravityreadings are corrected. Figure 10-11 shows atemperature conversion chart for an 80°Fhydrometer. You can also correct the specificgravity reading of a storage battery by adding 1point for each 3°F above 80°F, or by subtracting1 point for each 3°F below 80°F.

Adjusting Specific Gravity WARNING

Sometimes the specific gravity of a cell is morethan it should be. You can reduce it to withinlimits by removing some of the electrolyte andadding distilled water. As stated earlier, chargethe battery for 1 hour to mix the solution. Thentake hydrometer readings. Continue the adjust-ment until you get the desired true readings.

NOTE: Only authorized personnel should addacid to a battery. Acid with a specific gravityabove 1.350 is NEVER added to a battery.

Figure 10-11 .—Temperature conversion chart.

weight, or about 27 percent by volume. Distilledwater and sulfuric acid are used to prepare theelectrolyte. New batteries may be delivered withcontainers of concentrated sulfuric acid of 1.830specific gravity or electrolyte of 1.400 specificgravity. You must dilute both of these withdistilled water to make electrolyte of the properspecific gravity. Use a container made of glass,earthenware, rubber, or lead for diluting the acid.

When mixing electrolyte, ALWAYSPOUR ACID INTO WATER—NEVERpour water into acid. Pour the acid slowlyand cautiously to prevent excessive heatingand splashing. Stir the solution con-tinuously with a nonmetallic rod to mix theheavier acid with the lighter water. Thiswill keep the acid from sinking to thebottom.- When concentrated -acid isdiluted, the solution becomes very hot.

TREATMENT OF SPILLED ACIDMIXING ELECTROLYTE

The electrolyte of a fully charged batteryusually has about 38 percent sulfuric acid by

If acid or electrolyte from a lead-acid batterycomes into contact with the skin, wash theaffected area with a large amount of fresh water.

10-13

A small amount of water might do more harmthan good in spreading the acid burn. Afterwards,apply a salve such as petrolatum, boric acid, orzinc ointment. If none of these salves areavailable, clean lubricating oil will suffice. Youcan neutralize acid spilled on clothing with dilutedammonia or a solution of baking soda and water.

CAPACITY

The capacity of a battery is measured inampere-hours (amp-hr). The amp-hr capacity isequal to the product of the current in amperes andthe time in hours during which the battery issupplying this current. The amp-hr capacity variesinversely with the discharge current. The size ofa cell is determined generally by its amp-hrcapacity. The capacity of a cell depends on manyfactors. The most important of these are asfollows:

1.

2.

3.4.

5.

The area of the plates in contact with theelectrolyteThe quantity and specific gravity of theelectrolyteThe type of separatorsThe general condition of the battery (degreeof sulfating, plates buckled, separatorswarped, sediment in bottom of cells, andso forth)The final limiting voltage

RATING

Storage batteries are rated according to theirrate of discharge and amp-hr capacity. Mostbatteries are rated according to a 10-hour rate ofdischarge. That is, if a fully charged battery iscompletely discharged during a 10-hour period,it is discharged at the 10-hour rate. Thus, if abattery can deliver 20 amperes for 10 hours, thebattery has a rating of 20 × 10, or 200 amp-hr.The 10-hour rating is equal to the averagecurrent that a battery can supply withoutinterruption for 10 hours.

All standard batteries deliver 100 percent oftheir available capacity if they are discharged in10 hours or more. But they will deliver less thantheir available capacity if they are discharged ata faster rate. The faster they discharge, the lessamp-hr capacity they have.

READINGS WHEN CHARGEDAND DISCHARGED

At the conclusion of a 10-hour discharge teston a battery, the closed-circuit voltmeter readingwill be about 1.75 volts per cell. The specificgravity of the electrolyte will be about 1.060. Atthe completion of a charge, the closed-circuitvoltmeter reading at the finishing rate will beabout 2.4 to 2.6 volts per cell. The specific gravityof the electrolyte corrected to 80°F will then bebetween 1.210 and 1.220.

TYPES OF CHARGES

The following types of charges may be givento a storage battery, depending on the conditionof the battery:

Initial charge

Normal charge

Equalizing charge

Floating charge

Emergency charge

Initial Charge

Initial charge is a long, low-rate, formingcharge that is given to place a new battery inservice. When a battery is shipped dry, the batterymay be in the uncharged or dry-charged condi-tion. After the electrolyte has been added, the un-charged battery must be given an initial charge.The addition of electrolyte to the dry-chargedbattery is sufficient for an initial charge. Tocharge the battery, follow the manufacturer’sinstructions. These are shipped with each battery.If the manufacturer’s instructions are notavailable, refer to the instructions in currentdirectives.

Normal Charge

A normal charge is a routine charge. Youshould give it following the nameplate data duringthe ordinary cycle of operation. It restores thebattery to its charged condition. Observe thefollowing steps:

1. Determine the starting and finishing ratefrom the nameplate data.

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2.3.

4.

5.

6.

Add water, as necessary, to each cell.Connect the battery to the charging panel.Make sure the connections are clean andtight.Turn on the charging circuit. Set the cur-rent through the battery at the value givenas the starting rate.Check the temperature and specific gravityof pilot cells hourly.When the battery begins to gas freely,reduce the charging current to the finishingrate.

A normal charge is complete when the specificgravity corrected for temperature has reached avalue within 5 points (0.005) of the specific gravityobtained on the previous equalizing charge.

Equalizing Charge

An equalizing charge is an extended normalcharge given only at the finishing rate. You shouldperiodically conduct an equalizing charge toensure all the sulfate is driven from the plates andall the cells are restored to a uniform maximumspecific gravity. Continue the equalizing chargeuntil the hydrometer readings show no increasein corrected specific gravity for any cell over aperiod of 4 hours. You should take the readingsevery 30 minutes.

Floating Charge

You may maintain a battery at full charge byconnecting it across a charging source that has avoltage maintained within the limits of from 2.13to 2.17 volts per cell of the battery. In a floatingcharge, you determine the charging rate by thebattery voltage rather than by a definite currentvalue. Maintain the voltage between 2.13 and 2.17volts per cell with an average as close to 2.15 voltsas possible.

3. A battery cannot be brought to within 10points of normal charge of its specificgravity.

Emergency Charge 4. A battery has been in service 4 years.

Use an emergency charge when a battery mustbe recharged in the shortest possible time. Startthe charge at a much higher rate than is normallyused for charging. Use it only in an emergency.This type of charge may be harmful to the battery.

CHARGING RATE

Normally, the charging rate of Navy storagebatteries is given on the battery nameplate. If the

available charging equipment does not have thedesired charging rates, use the nearest availablerates. However, do not let the rate become so highthat violent gassing occurs. NEVER ALLOWTHE TEMPERATURE OF THE ELECTRO-LYTE IN ANY CELL TO RISE ABOVE 125°F(52°C).

CHARGING TIME

Continue the charge until the battery is fullycharged. Take frequent readings of specificgravity during the charge. Correct these readingsto 80°F. Then, compare them with the readingtaken before the battery was placed on charge.If you know the rise in specific gravity in pointsper amp-hr, the approximate time in hoursrequired to complete the charge is as follows:

Rise in specific gravity inpoints to complete charge

Rise in specific gravity in Charging ratepoints per amp-hr

×per amp

TEST DISCHARGE

The test discharge is the best method ofdetermining the capacity of a battery. Mostbattery switchboards are provided with equipmentfor giving test discharges. If proper equipment isnot available, a tender, a repair ship, or a shorestation may perform the test discharge. A batterytest discharge is required when one of the follow-ing conditions exists:

1. A functional test reveals a low output.2. One or more cells are found to have less

than normal voltage after an equalizingcharge.

An equalizing charge must always precede atest discharge. After the equalizing charge, thebattery is discharged at its 10-hour rate. This isdone until the total battery voltage drops to avalue equal to 1.75 times the number of cells inseries or the voltage of any individual cell dropsto 1.65 volts. Keep the rate of discharge constantthroughout the test discharge. Because standardbatteries are rated at the 10-hour capacity, thedischarge rate for a 100 amp-hr battery is 100/10,

10-15

or 10 amperes. If the temperature of the electro-lyte at the beginning of the charge is not exactly80°F, correct the time duration of the dischargefor the actual temperature of the battery.

A battery of 100 percent capacity dischargesat its 10-hour rate for 10 hours before reachingits low-voltage limit. If the battery or one of itscells reaches the low-voltage limit before the10-hour period has elapsed, discontinue thedischarge immediately and determine the per-centage of capacity using the following equation:

c = Ha x 100H t

Where

C = percentage of amp-hr capacity available

Ha = total hours of discharge

Ht = total hours for 100 percent capacity

For example, a 100 amp-hr, 6-volt batterydelivers an average current of 10 amperes for 10hours. At the end of this period, the batteryvoltage is 5.25 volts. On a later test the samebattery delivers an average current of 10 amperesfor only 7 hours. The discharge was stopped atthe end of this time because the voltage of themiddle cell was found to be only 1.65 volts. Thepercentage of capacity of the battery is now7/10 × 100, or 70 percent. Thus, the amp-hrcapacity of this battery is reduced to0.7 × 100 = 70 amp-hr.

Record the date for each test discharge on thestorage battery record sheet.

STATE OF CHARGE

After a battery is discharged completely fromfull charge at the 10-hour rate, the specific gravityhas dropped about 150 points to about 1.060. Youcan determine the number of points the specificgravity drops per amp-hr for each type of battery.For each amp-hr taken out of a battery, a definiteamount of acid is removed from the electrolyteand combined with plates.

For example, if a battery is discharged fromfull charge to the low-voltage limit at the 10-hourrate, and if 100 amp-hr are obtained with aspecific gravity drop of 150 points, there is a dropof 150/100, or 1.5 points per amp-hr delivered.If you know the reduction in specific gravity peramp-hr, you can predict the drop in specific

gravity for this battery, for any number of amp-hr delivered to a load. For example, if 70 amp-hrare delivered by the battery at the 10-hour rateor any other rate or collection of rates, the dropin specific gravity is 70 × 1.5, or 105 points.

Conversely, if the drop in specific gravity peramp-hr and the total drop in specific gravity areknown, you can determine the amp-hr deliveredby a battery. For example, if the specific gravityof the previously considered battery is 1.210 whenthe battery is fully charged and 1.150 when it ispartly discharged, the drop in specific gravity is1.210 minus 1.150, or 60 points, and the numberof amp-hr taken out of the battery is 60/1.5, or40 amp-hr. Thus, the number of amp-hr expendedin any battery discharge can be determined fromthe following items:

1. The specific gravity when the battery isfully charged

2. The specific gravity after the battery hasbeen discharged

3. The reduction in specific gravity peramp-hr

Voltage alone is not a reliable indication ofthe state of charge of a battery, except when thevoltage is near the low-voltage limit on discharge.During discharge, the voltage falls. The higher therate of discharge, the lower will be the terminalvoltage. Open-circuit voltage is of little valuebecause the variation between full charge andcomplete discharge is so small—only about 0.1volt per cell. However, abnormally low voltagedoes indicate injurious sulfation or some otherserious deterioration of the plates.

GASSING

When a battery is being charged, a portion ofthe energy is dissipated in the electrolysis of thewater in the electrolyte. Thus, hydrogen is releasedat the negative plates and oxygen at the positiveplates. These gases bubble up through the electro-lyte and collect in the air space at the top of thecell. If violent gassing occurs when the battery isfirst placed on charge, the charging rate is toohigh. If the rate is not too high, steady gassing,which develops as the charging proceeds, indicatesthat the battery is nearing a fully chargedcondition.

10-16

CAUTION

A mixture of hydrogen and air can bedangerously explosive. DO NOT permitsmoking, electric sparks, or open flamesnear charging batteries.

SUMMARY

The information provided in this chaptershould help you understand some of the basic

maintenance requirements of electrical equip-ment. Always use the PMS procedures whendoing preventive maintenance, or use theapplicable technical manual when troubleshoot-ing. Strictly follow safety precautions foundon MRCs and in technical manuals. Whenworking around electrical equipment, rememberthat safety is the most important aspect of the job.Use the tag-out procedures, test your meters, usethe two-man rule, and do not bypass any safetydevices.

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APPENDIX I

GLOSSARY

ALARM ACKNOWLEDGE—A push buttonthat must be depressed to silence an alarm horn.

ALLOWANCE PARTS LIST (APL)—Repairparts required for units having the equip-ment/component listed.

ALLOY—Any composition metal producedby the mixing of two or more metals or elements.

ALLOYING—The procedure of addingelements other than those usually comprising ametal or alloy to change its characteristics andproperties.

ALLOYING ELEMENTS—The elementsadded to nonferrous and ferrous metals and alloysto change their characteristics and properties.

ALTERNATING CURRENT (ac)—Anelectrical current that constantly changesamplitude and changes polarity at regularintervals.

AMBIENT—Surrounding on all sides,encompassing.

AMBIENT PRESSURE/TEMPERA-TURE—The surrounding pressure/temperature,such as the air pressure/temperature thatsurrounds a conductor in a compartment or apiece of equipment.

AMMETER—An instrument for measuringthe amount of electron flow (in amperes).

AMPERE (amp)—A unit of electrical currentor rate of flow of electrons. One volt across 1 ohmof resistance causes a current flow of 1 ampere.(Named after A. M. Ampere, a famous Frenchphysicist.)

AMPLITUDE—The size of a signal asmeasured from a reference line to a maximumvalue above or below the line. Generally used todescribe voltage, current, or power.

ANALOG DATA—Data represented incontinuous form, as contrasted with digital datahaving discrete values.

ANALOG SIGNAL—A measurable quantitythat is continuously variable throughout a givenrange and that is representative of a physicalquantity.

ANALOG TO DIGITAL (A/D) CON-VERSION—A conversion that takes an analoginput in the form of electrical voltage or currentand produces a digital output.

ANNULAR—In the form of or forming aring.

ANNUNCIATOR—A device that gives anaudible and a visual indication of an alarmcondition.

ANTISEIZE COMPOUND—A silicon-based,high-temperature lubricant applied to threadedcomponents to aid in their removal after they havebeen subjected to rapid heating and cooling.

ASBESTOS— A noncombustible, noncon-ductive, fiber-like mineral used as an insulatingmaterial.

ASBESTOSIS— Fibrosis of the lungs causedby inhalation of asbestos.

ATMOSPHERE—A unit of measure equalto 14.696 psi or 29.92 inches of mercury(1 atmosphere = 14.696 psi).

ATMOSPHERIC PRESSURE—The pressureof air at sea level, approximately 14.7 psi.

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AUTOMATIC BUS TRANSFER (ABT)—Normal and alternate power sources are providedto vital loads. These power sources are suppliedfrom separate switchboards through separatedcable runs. Upon loss of the normal power supply,the ABT automatically disconnects this source andswitches the load to the alternate source.

AUTOMATIC PARALLELING DEVICE(APD)—The APD automatically parallels anytwo generators when initiated by the EPCC.

AUXILIARY CONTROL CONSOLE(ACC)—The console in CCS used to monitor theFFG-7 class auxiliary systems.

BABBITT—A white alloy of tin, lead,copper, and antimony that is used for liningbearings.

BACK PRESSURE—A pressure exertedcontrary to the pressure producing the main flowon the discharge/exhaust side of an engine orpump.

BAFFLE—A plate, wall, or screen used todeflect, check, or otherwise regulate the flow ofa gas, liquid, sound waves, and so forth.

BATTERY—A device for converting chemicalenergy into electrical energy.

BATTERY CAPACITY—The amount ofenergy available from a battery. Battery capacityis expressed in ampere-hours.

BELL LOG—A printed record of changes inthe ship’s operative conditions, such as speed orpoint of control.

BLEED AIR—Air bled off the compressorstages of the GTEs. See BLEED AIR SYSTEM.

BLEED AIR SYSTEM (BAS)—Takes airextracted from the compressor stage of a GTE anduses it for anti-icing, prairie air, masker air, andLP gas turbine starting for off-line GTEs.

BLOCK DIAGRAM—A diagram in whichthe major components of an equipment or asystem are represented by squares, rectangles, orother geometric figures. The normal order ofprogression of signal flow, current flow, orcomponent relationship is represented by lines.

BLOW-IN DOORS—Doors located on thehigh hat assembly designed to open by solenoid-operated latch mechanisms if the inlet airflowbecomes too restricted for normal engineoperation.

BOILER RECORD SHEET—A NAVSEAform maintained for each boiler, which serves asa monthly summary of operation.

BORESCOPE—A small periscope (instru-ment) used to visually inspect internal enginecomponents.

BOYLE’S LAW—If the temperature of agas is kept constant, then the volume ofthe gas will be inversely proportional to thepressure.

BRITISH THERMAL UNIT (BTU)—Theamount of heat that will raise the temperature of1 pound of water 1° Fahrenheit (from 62°F to63°F).

BUS—An uninsulated power conductor (a baror wire) usually found in a switchboard.

BUS TIE BREAKER (BTB)—A device usedto connect one main switchboard to another mainswitchboard.

CALIBRATION—(1) The operation ofmaking an adjustment or marking a scaleso that the readings of an instrument conformto an accepted standard. (2) The checking ofreadings by comparison with an acceptedstandard.

CALORIE—The amount of heat requiredat a pressure of 1 atmosphere to raise thetemperature of 1 gram of water 1° Centi-grade.

CAPILLARY TUBE—A slender, thin-walled,small-bored tube used with remote-readingindicators.

CASUALTY—An event or series of eventsin progress during which equipment damageand/or personnel injury has already occurred.The nature and speed of these events are such thatproper and correct procedural steps will only serveto limit equipment damage and/or personnelinjury.

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CENTIGRADE (CELSIUS) SCALE—Athermometric scale on which the interval betweenthe freezing point (0°C) and the boilingpoint (100°C) of water is divided into 100equal parts or degrees, so that 0°C = 32°F and100°C = 212°F.

CENTRAL CONTROL STATION (CCS)—The main operating station from which a majorityof the engineering plant machinery can becontrolled and monitored.

CENTRIFUGAL FORCE—That force thattends to drive a thing or parts of a thing outwardfrom a center of rotation.

CIRCUIT BREAKER (CB)—A device usedto energize/de-energize an electrical circuit andfor interrupting the circuit when the currentbecomes excessive.

CLASSIFICATION AND/OR TYPE—Amethod of identifying and sorting various equip-ment and materials. For example: (1) checkvalve—swing, stop; (2) valve—solenoid, manual.

CLUTCH/BRAKE ASSEMBLY—A clutch/brake assembly for each GTE is mounted on theMRG housing to couple or decouple either or bothengines to the drive train, to stop and hold thepower turbine, and for shaft braking.

COALESCE—To grow together, unite, orfuse, as uniting small liquid particles into largedroplets. This principle is used to remove waterfrom fuel in the filter/separator.

COHESION—The force that causes moleculesthat are brought close together to stick together.

COMPARATOR—An instrument or machinefor comparing anything to be measured with astandard instrument. Specifically, a self-containedportable pneumatic comparison-type pressuregauge tester.

COMPONENT PARTS—(1) The integralpart of a component. (2) Individual units of asubassembly.

COMPRESSOR DISCHARGE PRESSURE(CDP)—Compressor discharge pressure is sensedby a pressure tap on the compressor dischargestatic pressure sensing line to the MFC and pipedto a base-mounted transducer on the GTM.

COMPRESSOR INLET TEMPERATURE(CIT or T2)—The temperature of the air enteringthe gas turbine compressor (GTM) as measuredat the front frame; one of the parameters usedfor calculating engine power output (torque) andscheduling combustion fuel flow and variablestator vane angle.

COMPRESSOR INLET TOTAL PRES-SURE (Pt 2)—The pressure sensed by a totalpressure probe mounted in the GTM compressorfront frame.

CONDENSATE—The product of conden-sation (the process of reducing from oneform to another and denser form, as steam towater).

CONDITION—The state of being of a device,such as ON-OFF, GO/NO-GO, and so forth.

CONDUCTIVITY—The quality or power ofconducting or transmitting heat, electricity, andso forth.

CONTROL AIR SYSTEM (COAS) ASSEM-BLY—The equipment that controls the com-pressed air used to operate the main clutch/brakeassemblies. One control air system unit is mountedon each side of each MRG. This system is not usedon the SSS clutch system.

CONTROL MODE—The method of systemcontrol at a given time.

CONTROL POWER—The power used tocontrol or operate a component.

CONTROL SIGNAL—The signal applied toa device that makes corrective changes in acontrolled process.

CONTROLLABLE REVERSIBLE PITCH(CRP) PROPELLER—A propeller whose bladepitch can be varied to control the amount of thrustin both the ahead and astern directions. (Knownas controllable pitch propeller (CPP) on FFG-7class ships.)

CONVERTER—A device for changing onetype of signal to another (for example, alternatingcurrent to direct current).

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COULOMB’S LAW—Also called the LAW’OF ELECTRIC CHARGES or the LAW OFELECTROSTATIC ATTRACTION. Coulomb’slaw states that charged bodies attract or repel eachother with a force that is directly proportional tothe product of their individual charges andinversely proportional to the square of thedistance between them.

CURRENT—The movement of electrons pasta reference point. The passage of electronsthrough a conductor. It is measured in amperes.

CYCLE—A complete cycle exists when thevoltage in an alternating current increases fromzero to a maximum point, then decreases throughzero to a maximum point in the opposite direc-tion, and returns to zero again.

DAMAGE CONTROL CONSOLE (DCC)—This console is located in CCS and providesmonitoring for hazardous conditions (fire, highbilge levels, and so forth). It also monitors theship’s firemain and can control the fire pumps.

DEADWEIGHT TESTER—A hydraulicbalance-type gauge tester operating on theprinciple of subjecting the gauge under test to ahydrostatic pressure created by applying weightsto a piston of known area. The weighted pistonapplies pressure to a fluid, such as oil, in thecylinder, which in turn is transmitted to the gaugethrough a system of piping.

DEAERATING FEED TANK (DFT)—Adevice used in the waste-heat boiler (WHB) systemto remove dissolved oxygen and noncondensablegases from the feedwater.

DEAERATOR—A device that removes airfrom oil (for example, the lube oil storage andconditioning assembly (LOSCA) tank whichseparates air from the scavenge oil).

DEMAND DISPLAY INDICATOR (DDI)—A numerical display that is used to read valuesof parameters within the engineering plant.

DENSITY—The quantity of matter containedin a body.

DIFFERENTIAL PRESSURE—The differ-ence between two pressures measured with respectto a common basis.

DIFFERENTIAL PRESSURE GAUGE—ABourdon-type gauge equipped with two Bourdontubes so arranged as to measure the difference inpressure between two pressure lines. Bellowsgauges also measure differential pressure.

DIFFUSER—A device that reduces thevelocity and increases the static pressure of a fluidpassing through a system.

DIGITAL—Pertaining to data in the form ofdigits.

DIGITAL SIGNAL—A signal in the form ofa series of discrete quantities that have two distinctlevels (for example, on/off).

DIGITAL TO ANALOG (D/A) CON-VERSION—A conversion that produces ananalog output in the form of voltage or currentfrom a digital input.

DIRECT CURRENT (dc)—An electric cur-rent that flows in one direction only.

DISTILLATE—The fresh water that isobtained from the distilling process.

DISTILLED WATER—Water that has beenpurified through a process of evaporation andcondensation.

EDUCTOR—A mixing tube (jet pump) thatis used as a liquid pump to dewater bilges andtanks. A GTM exhaust nozzle creates an eductoreffect to remove air from the enclosure.

ELECTRIC PLANT CONTROL CONSOLE(EPCC)—This console contains the controls andindicators used to remotely operate and monitorthe generators and the electrical distributionsystem.

ELECTRIC PLANT CONTROL ELEC-TRONICS ENCLOSURE (EPCEE)—TheEPCEE is a part of the EPCE. It contains powersupplies that provide the various operating voltagerequired by the EPCC on the DD and CG classships.

ELECTRIC PLANT CONTROL EQUIP-MENT (EPCE)—The EPCE provides centralizedremote control of the GTGS and electricaldistribution equipment. The EPCE includes theEPCC and EPCEE and is located in CCS.

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ELECTRICAL RESISTANCE—The opposi-tion offered by a substance or body to the passagethrough it of an electric current or magnetic flux.

ELECTRODE—Either terminal of an electricsource. An electrode may be a wire, a plate, orother electricity-conducting object.

ELECTROLYTE— A solution of a substancethat is capable of conducting electricity. Anelectrolyte may be in the form of a liquid or paste.

ELECTROMOTIVE FORCE—That whichmoves or tends to move electricity.

ELECTRONIC GOVERNOR (EC)—Asystem that uses an electronic control unit withan electrohydraulic governor actuator to controland regulate engine speed.

EMERGENCY—An event or series of eventsin progress which will cause damage to equipmentunless immediate, timely, and correct proceduralsteps are taken.

ENGINEERING CONTROL AND SUR-VEILLANCE SYSTEM (ECSS)—An automaticelectronic control and monitoring system usinganalog and digital circuitry to control the propul-sion and electric plant. The ECSS consists of thePLOE, PAMCE, SCE, EPCE, and PAMISE onthe DD and CG class ships.

ENGINEERING OPERATIONAL SE-QUENCING SYSTEM (EOSS)—A two-partsystem of operating instructions bound inbooks for each watch station. It providesdetailed operating procedures (EOP) and casualtycontrol procedures (EOCC) for the propulsionplant.

ENGINEER OFFICER—Often referred toas the engineering officer or chief engineer.

ENGINE ORDER TELEGRAPH (EOT)—A nonvoice communication system providedbetween the command station (pilot house), CCS,and the MER.

FAHRENHEIT SCALE—A thermometricscale, at which, under atmospheric pressure, theboiling point is 212°F and the freezing point is32°F above zero.

FAIL—The loss of control signal or power toa component. Also breakage or breakdown of acomponent or component part.

FAIL POSITION—The operating or physicalposition to which a device will go upon loss ofits control signal.

FATIGUE—The tendency of a material tobreak under repeated strain.

FAULT ALARM—This type of alarm isused in the fuel control system and the DCC. Itindicates that a sensor circuit has opened.

FEEDBACK—A value derived from acontrolled function and returned to the controllingfunction.

FERROUS—Refers to metals having iron asthe base metal.

FILAMENT—A threadlike conductor, as ofcarbon or metal, that is made incandescent by thepassage of an electric current.

FILTER—(1) A device that removes insolublecontaminants from the fluid of a fluid powersystem. (2) A device through which gas or liquidis passed; dirt, dust, and other impurities areremoved by the separating action.

FITTINGS, PIPE—A term applied to theconnections and outlets, with the exception ofvalves and couplings, that are attached to pipes.

FLAMMABLE— A combustible material thatburns easily, intensely, or quickly.

FOOT-POUND—A term used in torqueapplication representing a force of 1 poundapplied perpendicular to a moment arm 1 footlong.

FREE STANDING ELECTRONIC EN-CLOSURE (FSEE)—The FSEE provides thesupporting electronics and engine control inter-face between the GTM and the control consoles.One FSEE is located in each MER.

FREQUENCY—The number of cycles (as inan alternating electrical current) completed persecond.

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FUEL OIL SYSTEM—This system providesa continuous supply of clean fuel to the GTMs.

FUEL TRANSFER AND OIL BALLASTCONTROL PANEL (FTOBCP)—This panel islocated in CCS and is used to monitor the ship’sfuel tanks (FFG-7 class ships).

FUEL SYSTEM CONTROL CONSOLE(FSCC)—The FSCC is located in CCS and is thecentral station for monitoring and control of thefuel fill and transfer system on the DD and CGclass ships.

FULL POWER CONFIGURATION—Thecondition in which both engines (GTEs) of a setare engaged and driving the reduction gear andpropeller shaft.

FUNCTION—To perform the normal orcharacteristic action of anything, or special dutyor performance required of a person or thing inthe course of work.

FUNCTIONAL COMPONENT SYSTEM—A system of standardized units of carefullybalanced combinations of material, equipment,and/or personnel. Each unit is designed to per-form a specific task at an advanced base.

GALVANOMETER—An instrument formeasuring a small electric current, or fordetecting its presence or direction by themovements of a magnetic needle or of a coil ina magnetic field.

GAS GENERATOR (CC)—The gas-producing section of any GTE. It usually has acompressor, a combustor, a high-pressure turbine,an accessory drive system, and controls andaccessories.

GAS GENERATOR SPEED (Ngg)—Thespeed sensed by a magnetic pickup on the transfergearbox of the GTE.

GAS TURBINE ENGINE (GTE)—A gasturbine engine consists of a compressor, acombustor, a turbine, and an accessory drivesystem. Many variations of GTEs exist.

GAS TURBINE GENERATOR SET(GTGS)—The GTGS has a GTE, a reductiongearbox, and a generator.

GAS TURBINE MODULE (GTM)—TheGTM consists of the main propulsion gas turbineunit, including the GTE, base, enclosure, shockmounting system, fire detection and extinguishingsystem, and the enclosure environmental controlcomponents.

GAUGE PRESSURE—Pressure that ismeasured using atmospheric pressure for zeroreference.

GENERATOR BREAKER (GB)—The GB isused to connect a generator to its mainswitchboard.

GOVERNOR DROOP MODE—Droop modeis normally used only for paralleling with shorepower. Since shore power is an infinite bus (fixedfrequency), droop mode is necessary to controlthe load carried by the generator. If a generatoris paralleled with shore power, and an attempt ismade to operate it in isochronous mode insteadof droop mode, the generator governor speedreference can never be satisfied because thegenerator frequency is being held constantby the infinite bus. If the generator governorspeed reference is above the shore powerfrequency, the load carried by the generatorwill increase beyond capacity (overload) inan effort to raise the shore power frequency.If the speed reference is below the shore powerfrequency, the load will decrease and reverse(reverse power) in an effort to lower the shorepower frequency. The resulting overload orreverse power will trip the GB.

GOVERNOR ISOCHRONOUS MODE—This mode is normally used for generatoroperation. This mode provides a constantfrequency for all load conditions. When operatingtwo (or more) generators in parallel, isochronousmode also provides equal load sharing betweenunits.

HAZARD ALARM—This type of alarm isused in the fuel control system and DCC. Itshows that a parameter has exceeded preset safelimits.

HEAD TANK—The tank located higher thanother system components to provide a positivepressure to a system by gravity when the systemis secured.

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HELIX—(1) A tube or solid material(gear teeth) wrapped like threads on a screw.(2) Anything having a spiral shape. (Math-ematically, a helix is the shape of the curve formedon any cylinder by a straight line in a plane thatis wrapped around the cylinder, such as anordinary screw thread.)

HERTZ (Hz)—A unit of frequency equal toone cycle per second.

HIGH-PRESSURE (HP) AIR SYSTEM—Asystem that is designed for a nominal operatingpressure in excess of 1000 psig.

HYDRAULIC—Conveyed, operated, ormoved by water or other liquid in motion.

HYDRAULIC ACTUATOR—A device thatconverts hydraulic pressure to mechanicalmovement.

HYDRAULIC OIL POWER MODULE(HOPM)— The HOPM is located near the MRG.It delivers pressure-regulated oil to the power oilpiping and the control oil piping.

HYDROMETER—An instrument used tomeasure specific gravity. In batteries hydrometersare used to indicate the state of charge by thespecific gravity of the electrolyte.

HYDROSTATIC—Related to liquids at restor the pressures they exert or transmit.

HYSTERESIS—The inability of an elasticmember to return to its original position after ithas been stressed. To lag.

INDUCTION (ELECTRICAL)—The processby which (1) an electrical conductor becomeselectrified when near a charged body, (2) amagnetizable body becomes magnetized when ina magnetic field, or (3) an electromotive force(emf) is produced in a circuit by varying themagnetic field linked with the circuit.

INERT GAS—A gas that has no activechemical properties.

INFORMATION CONTROL CONSOLE(ICC)—The ICC is part of the ECU. The ICCNo. 1 is the panel used to program and run thecomputer. The ICC No. 2 is the tape reader usedto input the program into the ECU.

INLET GUIDE VANES (IGVs)—Thevariable vanes ahead of the first stage ofcompressor blades of a GTE. Their function isto guide the inlet air into the GTE compressor atthe optimum angle.

INLET PLENUM—That section for the GTEinlet air passage that is contained within the engineenclosure.

INTEGRATED THROTTLE CONTROL(ITC)—The ITC has control electronics locatedin the PACC that allow single lever control ofthrottle and pitch of one shaft. Two levers (oneper shaft) are located at the SCC and at the PACCon the DD and CG class ships.

INTERLOCK—A device that prevents anaction from taking place until all requiredconditions are met.

JP-5—The principal use of JP-5 is fuel forhelicopters and small boats.

KELVIN SCALE—A thermometric scale onwhich the units are the same size as the Celsiusscale with the zero point shifted to absolute zero.Absolute zero on the Celsius scale is -273.15°.

KILOWATT—A unit of electrical powerequal to 1,000 watts. (A watt is a unit of powerequal to the rate of work represented by acurrent of 1 ampere under a pressure of 1 volt.)

KINETIC ENERGY—Energy in motion.

LABYRINTH/HONEYCOMB SEALS—This type of seal combines a rotating element anda honeycomb stationary element to form an airseal. Used in gas turbines to maintain closetolerances over a large temperature range.

LABYRINTH/WINDBACK SEALS—Thistype of seal combines a rotating element with asmooth surface stationary element to form an oilseal. This type of seal is used with an air seal witha pressurization air cavity between the two seals.Pressure in the pressurization air cavity is alwaysgreater than the sump pressure. Therefore, flowacross the seal is toward the sump. This preventsoil leakage from the sump. The windback is acoarse thread on the rotating element of the oilseal which uses screw action (windback) to forceany oil that might leak across the seal back intothe sump.

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LEFT-HAND RULE—(1) For generators: Ifthe thumb, first finger, and second finger of theleft hand are stretched at right angles to oneanother, with the thumb representing the directionof motion, the first finger representing the direc-tion of magnetic lines of force, and the secondfinger representing the direction of electron flow,the relationship between the directions will thenbe correct for a conductor in the armature of agenerator. (2) For a current-carrying wire: If thefingers of the left hand are placed around the wirein such a way that the thumb points in the direc-tion of electron flow, the fingers will be pointingin the direction of the magnetic field.

LIQUID FUEL VALVE (LFV)—This valvemeters the required amount of fuel for all engineoperating conditions for the Allison 501-K17GTE.

LOAD SHEDDING—Protects a generatorfrom overloading by automatically droppingpreselected loads when generator out put reaches100 percent.

LOCAL CONTROL—Start-up and operationof equipment by manual controls attached to themachinery, or by an electric panel attached to themachinery or located nearby.

LOCAL OPERATING PANEL (LOP)—TheLOP is the local operating station for GTEs onthe FFG-7 class ships. It is located in the MERand is used primarily for maintenance.

LOCKED TRAIN—A designation applied toa reduction gear set where when one gear isturned, all gears in the set will turn.

LOGIC—A method for describing the existingcondition of circuits and devices that can remainat only one of two opposite conditions at aparticular time, such as ON or OFF, UP orDOWN, IN or OUT.

LUBE OIL STORAGE AND CONDITION-ING ASSEMBLY (LOSCA)—The LOSCA ismounted remotely from the GTM and is a unitwith a lube oil storage tank, a heat exchanger, ascavenge oil duplex filter, and a scavenge oil checkvalve (all mounted on a common base). Itsfunction is to provide the GTM with an adequatesupply of cooled, clean lube oil. It also hasinstrumentation for remote monitoring of oiltemperature, filter differential pressure, andhigh/low tank level alarm.

MAIN FUEL CONTROL (MFC)—A hydro-mechanical device on the propulsion GTE thatcontrols Ngg, schedules acceleration fuel flow,deceleration fuel flow, and stator vane angle forstall-free, optimum performance over theoperating range of the GTE.

MAIN REDUCTION GEAR (MRG) AS-SEMBLY—A locked train, double reduction geardesigned to reduce the rpm output of the GTEand drive the propeller shaft.

MANUAL BUS TRANSFER (MBT)—TheMBT provides for manual selection betweennormal and alternate power sources.

MASKER AIR SYSTEM—This systemdisguises the sound signature of the ship and alterstransmission of machinery noise to the water byemitting air from small holes in the emitter ringson the ship’s hull.

MASS—The measure of the quantity ofmatter contained in a body.

MILITARY STANDARDS (MILSTDs)—Aformalized set of standards for supplies, equip-ment, and design work purchased by the UnitedStat es Armed Forces.

MOMENT ARM—The length of a torquewrench from the center of pivot to the point whereforce is applied.

MONITORING POINT—The physical loca-tion at which any indicating device displays thevalue of a parameter at some control station.

MOST REMOTE BEARING—The bearinglocated at the hydraulically most remote point inthe system.

MOTOR—(l) A rotating machine thattransforms electrical energy into mechanicalenergy. (2) An actuator that converts fluid powerto rotary mechanical force and motion.

MOTOR CONTROLLER—A device orgroup of devices that governs, in some pre-determined manner, the operation of the motorto which it is attached.

MULTIPLEXING—A system of transmittingtwo or more messages or signals over a commoncircuit.

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NONFERROUS METAL—Metal that iscomposed primarily of a metallic element, orelements other than iron.

NOZZLE—A taper or restriction used tospeed up or direct the flow of gas or liquid.

OCCUPATIONAL STANDARDS (OCC-STDs)—Requirements that describe the work ofeach Navy rating.

OHM—The unit of electrical resistance.

OHM’S LAW—A fundamental electrical lawwhich expresses the relationship between voltage,current, and resistance in dc circuits or voltage,current, and impedance in ac circuits.

OIL DISTRIBUTION (OD) BOX—This boxis located at the forward end of each MRGassembly. It directs power oil from the HOPMto the propeller hub through the shaft bore. TheOD box also establishes propeller pitch by usingcontrol oil from the HOPM to position the valverod, which extends through the shaft to the hub.

ONE-LINE SCHEMATIC—A drawing of asystem using only one line to show the tie-in ofvarious components; for example, the threeconductors needed to transmit three-phase powerare represented by a single line.

OPEN LOOP—A system having no feedback.

OPERATING CHARACTERISTICS—Thecombination of a parameter and its set point.

ORIFICE—A circular opening in a flowpassage that acts as a flow restriction.

OSCILLATOR—A fluidic device that in-corporates a feedback system and generates afrequency determined by such factors as viscosityof the fluid passing through the device. This devicecan be used as a frequency generator or as atemperature/viscosity sensor.

PACKING—A class of seal that providesa seal between two parts of a unit that move inrelation to each other.

PARAMETER—A variable, such astemperature, pressure, flow rate, voltage, current,or frequency that may be indicated, monitored,checked, or sensed in any way during operationor testing.

PASCAL’S PRINCIPLE—Pressure appliedon a confined fluid is transmitted undiminishedin every direction.

PERMANENT MAGNET ALTERNATOR(PMA)—The PMA is mounted on the generatorshaft extension of each GTGS and supplies speedsensing and power to the EG. The PMA alsosupplies initial generator excitation.

PHASE DIFFERENCE—The time in elec-trical degree by which one wave leads or lagsanother.

PIPE—A tube or hollow body for conductinga liquid or gas. Dimensions of a pipe aredesignated by nominal (approximate) outsidediameter (OD) and wall thickness.

PIPING—An assembly of pipe or tubing,valves, and fittings that forms the transferringpart of a system.

PITCH—A term applied to the distance apropeller will advance during one revolution.

POLARITY (ELECTRICAL)—The particularstate (positive or negative) of a body withreference to the two poles.

POPPET-TYPE CHECK VALVE—A valvethat moves into and from its seat to prevent oilfrom draining into the GTGS when the engine isshut down.

PORTABLE STEERING CONTROL UNIT(PSCU)—The PSCU is a portable steeringcontrol unit that can be mounted on a bridgewing.

POTABLE WATER—Water that is suitablefor drinking. The potable water system suppliesscuttlebutts, sinks, showers, sculleries, andgalleys, as well as provides makeup water forvarious freshwater cooling systems.

POTENTIAL—The amount of charge held bya body as compared to another point or body.Usually measured in volts.

POTENTIAL ENERGY—(1) Energy at rest;stored energy. (2) The energy a substance hasbecause of its position, its condition, or itschemical composition.

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POTENTIOMETER—A variable resistanceunit having a rotating contact arm that can be setat any desired point along a resistance element.

POUNDS PER SQUARE INCH (psi)—Aunit of pressure.

POUNDS PER SQUARE INCH ABSOLUTE(psia)—A unit of pressure.

POUNDS PER SQUARE INCH DIFFER-ENTIAL (psid)—A unit of pressure. Also knownas delta (Ap) pressure.

POUNDS PER SQUARE INCH GAUGE(psig)—A unit of pressure.

POWER LEVER ANGLE (PLA)—A rotaryactuator mounted on the side of the GTE fuelpump and its output shaft lever. It is mechanicallyconnected to the MFC power lever. The PLAactuator supplies the torque to position the MFCpower lever at the commanded rate.

POWER ON RESET—A signal generated byeach electronics enclosure when it is energized.This signal preconditions electronic circuitry inthe control console (whose power is supplied bythat electronics enclosure) to a known state foroperational purpose during application of powerto the console.

POWER SUPPLY—The module that con-verts the 115-volt, 60-hertz incoming power to acor dc power at a more suitable voltage level.

POWER TAKEOFF (PTO)—The drive shaftbetween the GTGS gas turbine engine and thereduction gear. Transfers power from the gasturbine to the reduction gear to drive thegenerator.

POWER TURBINE (PT)—The GTE turbinethat converts the GG exhaust into energy andtransmits the resulting rotational force via theattached output shaft.

POWER TURBINE INLET TEMPERA-TURE (T5.4)—The temperature sensed bythermocouples installed in the GTE midframe.

POWER TURBINE INLET TOTAL PRES-SURE (Pt 5.4)—The pressure sensed by five totalpressure probes located in the GTE turbine mid-frame and piped to a transducer on the bottomof the GTM.

POWER TURBINE SPEED (Np t)—Thespeed sensed by magnetic pickups in the GTEturbine rear frame.

PRAIRIE AIR SYSTEM—This system emitscooled bleed air from small holes along the leadingedges of the propeller blades. The resulting airbubbles disturb the thrashing sound so identifica-tion of the type of ship through sonar detectionbecomes unreliable.

PRESSURE—Pressure is force per unit ofarea, usually expressed as psi.

PRESSURE FEED SYSTEM—A system inwhich pressure (rather than gravity) is used tomaintain flow.

PRIME MOVER—(1) The source ofmotion—as a gas turbine engine. (2) Thesource of mechanical power used to drivea pump or compressor. (3) The source ofmechanical power used to drive the rotor ofa generator.

PRINTED CIRCUIT BOARD (PCB)—(1)An electronic assembly mounted on a card,using etched conductors. Also called printedwire board (PWB). (2) Devices usually plug-ged into receptacles that are mounted inmodules.

PRIORITY—Order established by relativeimportance of the function.

PROPELLER—A propulsive device con-sisting of a boss or hub carrying two or moreradial blades. Also called a SCREW.

PROPULSION AND AUXILIARY CON-TROL CONSOLE (PACC)—This console islocated in CCS and is part of the PAMCE. Itcontains the electronic equipment capable ofcontrolling and monitoring both propulsion plantsand auxiliary equipment on a DD or CG classship.

PROPULSION AND AUXILIARYCONTROL ELECTRONICS ENCLOSURE(PACEE)—This enclosure is located in CCS andhas the electronics that supply power to the PACCon a DD or CG class ship.

AI-10

PROPULSION AND AUXILIARY MA-CHINERY CONTROL EQUIPMENT(PAMCE)—This equipment is located in CCS, ispart of the ECSS, and includes the PACC andPACEE. This equipment provides centralizedcontrol and monitoring of both main propulsionplants and auxiliary machinery on a DD or CGclass ship.

PROPULSION AUXILIARY MACHINERYINFORMATION SYSTEM EQUIPMENT(PAMISE)—This equipment is located in CCSand is part of the ECSS. This equipment receives,evaluates, and logs the engineering plant perform-ance, status, and alarm state. The PAMISEcontains the CISE and S/CE No. 1 on a DD orCG class ship.

PROPULSION CONTROL CONSOLE(PCC)—This is the main engine control consolein CCS on a FFG-7 class ship. It is used forstarting, stopping, and controlling the GTEs andpropeller shaft.

PROPULSION LOCAL CONTROL CON-SOLE (PLCC)—The PLCC is located in eachengine room and is part of the PLOE. It hascontrols and indicators necessary for operator’scontrol of one main propulsion plant and itssupporting auxiliaries on a DD or CG class ship.

PROPULSION LOCAL CONSOLE ELEC-TRONICS ENCLOSURE (PLCEE)—ThePLCEE is located in each engine room and is partof the PLOE. It has the electronics that supplypower to the FSEE and PLCC on a DD or CGclass ship.

PROPULSION LOCAL OPERATINGEQUIPMENT (PLOE)—The PLOE is located ineach engine room and is part of the ECSS. Itincludes the PLCC and PLCEE. The PLOEprovides for local control and monitoring of themain propulsion GTE and the associated auxiliaryequipment on a DD or CG class ship.

PUMP—(1) A device that converts mechanicalenergy into fluid energy. (2) A device that raises,transfers, or compresses fluids or gasses.

PUMP CAPACITY—The amount of fluid apump can move in a given period of time, usuallystated in gallons per minute (gpm).

PUSH-BUTTON SWITCH INDICATOR—A panel-mounted device that has both switch con-tacts and indicating lights. The contacts areactuated by depressing the device face. The in-dicator lights are labeled and wired for indicatingalarm or status.

PYROMETER—An instrument for measur-ing temperatures by the change of electricresistance, the production of a thermoelectriccurrent.

RECEIVER—(1) A container in whichcompressed gas is stored to supply pneumaticpower. (2) A reservoir for pressure refrigerant.

REDUCER— (1) Any coupling or fitting thatconnects a large opening to a smaller pipe or hose.(2) A device that reduces pressure in a fluid (gasor liquid) system.

REFERENCE DESIGNATION—A com-bination of letters and numbers to identify partson electrical and electronic drawings. The lettersdesignate the type of part, and the numbersdesignate the specific part. For example:Reference designator R-12 indicates the 12thresistor in a circuit.

REFERENCE SIGNAL— A command signalthat requests a specific final condition.

RELATIVE HUMIDITY—The ratio of theamount of water vapor in the air at a giventemperature to the maximum capacity of watervapor in the air at the same temperature.

RELAY—A magnetically operated switch thatmakes and breaks the flow of current in a circuit.

REMOTE MANUAL OPERATION—Human operation of a process by manualmanipulation of loading signals to the finalcontrol elements.

RESISTANCE— The opposition to the flowof current caused by the nature and physicaldimensions of a conductor.

RESISTANCE TEMPERATURE DETEC-TOR (RTD)—These temperature sensors work onthe principle that as temperature increases, theconductive material exposed to this temperatureincreases its electrical resistance.

AI-11

RESISTANCE TEMPERATURE ELE-MENT (RTE)—Same as RTD.

RESISTOR—A device possessing the propertyof electrical resistance.

RHEOSTAT—A variable resistor having onefixed and one moveable terminal.

RPM AND PITCH INDICATOR UNIT(RPIU)—This unit is mounted in the pilot houseand is part of the SCE. It is identical to theBWDU except that it also displays port and star-board CRP propeller pitch on a DD or CG classship.

SCAVENGE PUMP—A pump used toremove oil from a sump and return it to the oilsupply tank.

SCHEMATIC DIAGRAM—A diagram usinggraphic symbols to show how a circuit functionselectrically.

SECURE—(1) To make fast or safe. (2) Theorder given on completion of a drill or exercise.(3) The procedure followed with any piece ofequipment that is to be shut down.

SECURED PLANT CONFIGURATION(MODE)— The condition in which engines of aset are disengaged from the reduction gear/pro-pulsion shaft on a DD or CG class ship.

SELECTOR SWITCH—Usually a rotary-typeswitch with more than two line connections. Theselector switch permits the connection (by a jackoutlet) of a permanently connected handset to anyother wired-in circuit. In some stations, whereonly two circuits are involved, a double-throwtoggle switch is normally used.

SENSING ELEMENT OR SENSOR—Thepart of an instrument that first takes energy fromthe measured medium to produce a conditionrepresenting the value of the measured variable.

SENSING POINT—Physical and/or func-tional point in a system at which a signal may bedetected or monitored in an automatic operation.

SENSITIVITY—The smallest change in thevalue of a variable being measured to which theinstrument will respond.

SENSOR— A component that senses physicalvariables and produces a signal to be observed orto actuate other elements in a control system.Temperature, pressure, sound, and positionsensors are examples.

SEQUENCE VALVE—An automatic valve ina fluid power system that causes one actuationto follow another in definite order.

SEQUENTIALLY—In a predesigned se-quence, not necessarily in numerical order.

SERIAL DATA BUS—A major communica-tion link between ship control equipment,PAMCE, and PLOE. The bus is time-sharedbetween the consoles. Control and statusinformation is exchanged in the form of serialdata words on a DD or CG class ship.

SERVICE TANKS—The service tanks thatcontain purified fuel from the storage tanks.

SET POINT—The numerical value of aparameter at which an alarm is actuated.

SHELL INSERT BEARING—A bearing inwhich the wearing surface is installed on a thinshell. This shell is removable from the bearingbody.

SHIM—A thin layer of metal or othermaterial used to true up a machine or inserted inbearings to permit adjustments after bearing wear.

SHIP CONTROL CONSOLE (SCC)—Thisconsole is located on the bridge. It has equipmentfor operator control of ship’s speed and direction.

SHIP CONTROL EQUIPMENT (SCE)—Bridge-located equipment of the ECSS, whichincludes SCC, SCEEE, PSCU, BWDU, andRPIU on a DD or CG class ship.

SHIP CONTROL EQUIPMENT ELEC-TRONICS ENCLOSURE (SCEEE)—TheSCEEE (located in CIC) is part of the SCE. Ithas power supplies that provide the variousoperating voltages required for the SCC, BWDU,and RPIU on a DD or CG class ship.

SHIP’S SERVICE AIR SYSTEM (SSAS)—This system supplies compressed air at 150 psigto a majority of the ship’s pneumatically operatedequipment.

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SHIP’S SERVICE DIESEL GENERATOR(SSDG)—The SSDG is the main source of elec-trical power for a ship. It uses a diesel engine asthe prime mover for the generator.

SHIP’S SERVICE GAS TURBINE GEN-ERATOR (SSGTG)—The SSGTG is the mainsource of electrical power for a ship. It uses a gasturbine engine as the prime mover for thegenerator.

SHORT CIRCUIT—A low resistance connec-tion between two points of different potential ina circuit.

SHUTTLE VALVE—A valve that is used todirect fluid automatically from either the normalsource or an alternate source to the actuator.

SIGNAL CONDITIONING ENCLOSURE(S/CE)— A part of the PAMISE that provides themajor input interface between the propulsionplant machinery and the ECSS control consoles.The S/CE accepts inputs from the plantmachinery and outputs normalized signals to theECSS control consoles. It also has alarm detec-tion and alarm output circuitry. One S/CE islocated in each main engine room and one is partof the CISE (located in CCS) on a DD or CG classship.

SOLID STATE—A class of electronics com-ponents, such as transistors, diodes, integratedcircuits, silicon controlled rectifiers, and so forth.

SPECIFIC GRAVITY—The ratio of theweight of a given volume of any substance to theweight of an equal volume of distilled water. Sincethe distilled water weighs approximately 62.4pounds per cubic foot, any substance whichweighs less than this has a specific gravity of lessthan one and will float on water. Any substanceof greater weight per cubic foot has a specificgravity of more than one and will sink. Specificgravity of gases is based in a like manner on theweight of air.

SPECIFIC HEAT—The amount of heatrequired to raise the temperature of 1 pound ofa substance 1°F. All substances are compared towater, which has a specific heat of 1 BTU/lb/ °F.

SPLIT PLANT CONFIGURATION(MODE)— The condition in which only oneengine of a set is driving the reduction gear/pro-pulsion shaft.

STERN TUBE—(1) The bearing supportingthe propeller shaft where it emerges from the ship.(2) A watertight enclosure for the propeller shaft.

STERN TUBE FLUSHING WATER—Watercirculated through the stern tube from inboardto prevent accumulation of debris in the stern tubewhile the ship is at rest or backing down.

STRAIN—The deformation of a materialbody under the action of applied forces (stress).

STRIPPING SYSTEM—A system providedto strip all petroleum tanks of water and sediment.

STUFFING BOX—(1) A chamber and closurewith manual adjustment for a sealing device. (2)A device to prevent fluid leakage between amoving and a fixed part in a steam engineeringplant. (3) A fitting designed to permit the freepassage or revolution of a rod or a pipe whilecontrolling or preventing the passage by it ofwater, steam, and so forth.

STUFFING TUBE—A packed tube thatmakes a watertight fitting for a cable or small pipepassing through a bulkhead.

SUMMARY ALARM/FAULT—An indica-tor at a console that indicates to an operator thatone of several abnormal conditions has occurredon a certain piece of equipment.

SYNCHRO SELF SHIFTING (SSS)CLUTCH—The SSS clutch is a fully automatic,freewheel device that transmits power throughgear-toothed elements.

SYNCHRONOUS— Happening at the sametime.

SYSTEM—A grouping of components orequipment joined to serve a common purpose.

SYSTEM INTERRELATION—Specific in-dividual operations in one system affecting theoperation in another system.

TACHOMETER GENERATOR—A devicefor converting rotational speed into an electricalquantity or signal.

TAIL SHAFT—The aft section of the shaftthat receives the propeller.

AI-13

TANK LEVEL INDICATOR (TLI)—Ahydrostatic-type tank gauge, usually operating onthe principle of balancing a head of liquid in atank against a column of mercury, or on thebalanced hydraulic principle employing a float-actuated remote reading dial gauge. It is used tomonitor the fluid level of a tank.

TEST POINT—A position in a circuit whereinstruments can be inserted for test purposes.

THERMAL ENERGY—Energy contained inor derived from heat.

THERMOCOUPLE— (1) A bimetallic devicecapable of producing an electromotive forceroughly proportional to temperature differenceson its hot and cold junction ends. (2) A junctionof two dissimilar metals that produces a voltagewhen heated.

THERMOCOUPLE PYROMETER—A tem-perature measuring instrument using the changeof electric resistance of a conductor when heatedto indicate the temperature being measured.

THRUST BEARING—Bearings that limit theaxial (longitudinal) movement of the shaft.

TOLERANCE— The allowable deviationfrom a specification or standard.

TORQUE—A force or combination of forcesthat produce or tends to produce a twisting orrotary motion.

TRANSDUCER— (1) A device that convertsa mechanical input signal into an electrical out-put signal. (2) Generally, a device that convertsenergy from one form into another, alwaysretaining the characteristic amplitude variationsof the energy converted.

TRANSFORMER— A device composed oftwo or more coils, linked by magnetic lines offorce, used to transfer electrical energy from onecircuit to another. Also, an electrical device usedto step up or step down an ac voltage.

TURBINE INLET TEMPERATURE (TIT)—The GTGS turbine inlet temperature on theAllison 501-K17. Known as T5.4 for an LM2500GTE.

TURBINE OVERTEMPERATURE PRO-TECTION SYSTEM (TOPS)—A system used toprotect a surviving generator from overload in theevent of another generator failure on a DD or CGclass ship.

TURNING GEAR—An electric motor-drivengear arrangement that slowly rotates idle propul-sion shafts and main reduction gears.

UNINTERRUPTIBLE POWER SUPPLY(UPS) SYSTEM—Critical ship control systemshave a UPS as an emergency power source. TheUPS is used to maintain operations during anyinterruption of the normal power source.

UNIT—A value, quantity, or magnitude interms of which other values, quantities, ormagnitudes are expressed (for example, yard,pound, gallon).

VACUUM— Pressure less than atmosphericpressure.

VALVE—A mechanism that can be openedor closed to control the flow of a liquid,gas, or vapor from one place to anotherplace.

VARIABLE STATOR VANE (VSV)—Compressor stator vanes that are mechanicallyvaried to provide optimum, stall-free compressorperformance over a wide operating range.

VELOCITY—The rate of motion in aparticular direction. The velocity of fluid flow isusually measured in feet per second.

VISCOSIMETER— A device that determinesthe viscosity of a given sample of oil.

VISCOSITY— The internal resistance of afluid which tends to prevent it from flowing.

VOLT—The unit of electrical potential.

VOLTAGE—The electric potential difference,expressed in volts.

VOLTMETER— An instrument for mea-suring in volts the difference of potentialbetween different points of an electrical cir-cuit.

AI-14

VOLUME—The amount of space thatmatter occupies.

WATT—The unit of electric power equal tothe rate of work represented by a current of 1ampere under a pressure of 1 volt.

WATCH STATION—Duties, assignments, orresponsibilities that an individual or group of in-dividuals may be called upon to carry out. Not

WATTMETER—An instrument for measur-ing electric power in watts.

necessarily a normally manned position with a WEIGHT—The force of gravity exerted onwatch bill assignment. an object.

AI-15

APPENDIX II

ABBREVIATIONS AND ACRONYMS

This appendix is a listing of the abbreviations and acronyms used in thistext. Although this is an extensive listing, it is not an all-inclusive list ofabbreviations and acronyms used by the Gas Turbine Systems Technicians.The GSE3/GSM3, NAVEDTRA 10564, volume 2, will also have anappendix II with abbreviations and acronyms used in the text. However, thislist will help form a basis for your qualification under the PQS system andallow for rapid access to terms used by Gas Turbine Systems Technicians.

A

ABT—automatic bus transfer

ac—alternating current

AFFF—aqueous film forming foam

amp-hr—ampere-hours

AMR—auxiliary machinery room

APD—automatic paralleling device

B

BS&W—bottom sediment and water

C

°C—degree Centigrade

CB—circuit breaker

CCS—central control station

cfm—cubic feet per minute

CLEP—College Level Examination Program

COAS—control air system

CPP—controllable pitch propeller

CPR—cardiopulmonary resuscitation

CBP—controllable reversible pitch

CSMP—Current Ship’s Maintenance Project

CT—current transformer

D

db—decibel

dc—direct current

DDI—demand display indicator

DFT—deaerating feed tank

DSP—disodium phosphate

E

ECS—electronics control station

ECSS—engineering control and surveillancesystem

EDO—engineering duty officer

EDORM—Engineering Department Organizationand Regulations Manual

EM—Electrician’s Mate

AII-1

emf—electromotive force

EN—Engineman

EOCC—engineering operational casualty control

EOOW—engineering officer of the watch

EOP—engineering operational procedures

EOSS—Engineering Operational SequencingSystem

EPCC—electric plant control console

epm—equivalence per million

ER—engine room

ESO—educational services officer

F

°F—degree Fahrenheit

FMS—final multiple score

FOD—foreign object damage

FSEE—free standing electronic enclosure

FT—Fire Control Technician

ft-lb—foot-pound

G

gpm—gallons per minute

GS—Gas Turbine Systems Technician

GSE—Gas Turbine Systems Technician (Elec-trical)

GSM— Gas Turbine Systems Technician (Me-chanical)

GTE— gas turbine engine

GTG/GTGS— gas turbine generator/gas turbinegenerator set

GTM— gas turbine module

H

HOPM—hydraulic oil power module

HP—high pressure

hp—horsepower

HPAC—high-pressure air compressor

HS—high speed

Hz—hertz

I

IC—Interior Communications Electrician

ID—inside diameter

in.lb—inch-pound

in.H2O— inches of water

in.Hg—inches of mercury

IPS—internal pipe size

IR—infrared

K

K—Kelvin

kΩΩ —kilohms

kW—kilowatt

L

lb-ft—pound-feet

Ib/hr—pounds per hour

lb-in—pound-inch

LFV—liquid fuel valve

LMET—Leadership, Management, and Educa-tion Training

AII-2

LOCOP—local operating panel (DD, DDG, and NEC—Naval Enlisted Classification CodeCG)

LOP—local operating panel (FFG)

LP—low pressure

LPAC—low-pressure air compressor

LS—low speed

LSB—line shaft bearing

lube—lubricating

LVP—low-voltage protection

LVR—low-voltage release

LVRE—low-voltage release effect

M

mA—milliampere

MBT—manual bus transfer

MDS—maintenance data system

MER—main engine room

mg/l—milligram per liter

MILSPEC—military specification

MILSTD—military standard

MRC—maintenance requirement card

MRG—main reduction gear

N

NEETS—Navy Electricity and Electronics Train-ing Series

NETPMSA—Naval Education and TrainingProgram Management Support Activity

NRTC—nonresident training course

NSTM—Naval Ships’ Technical Manual

O

OCCSTD—occupational standard

OD—outside diameter

OD BOX—oil distribution box

OOD—officer of the deck

P

PA—prairie air

PACC—propulsion and auxiliary control console

PAR—Personnel Advancement Requirement

PCB—printed circuit board

PCC—propulsion control console

PLCC—propulsion local control console

PMA—performance mark average

PMS—Planned Maintenance System

ppm—parts per million

NATO—North Atlantic Treaty Organization PQS—Personnel Qualification Standards

NAVEDTRA—Naval Education and Training psfa—pounds per square foot absolute

NAVSEA—Naval Sea Systems Command psi—pounds per square inch

NAVSHIPS—Naval ships (drawings) psia—pounds per square inch absolute

NAVSTD—naval standard psig—pounds per square inch gauge

AII-3

PT—power turbine

Pt 5 .4—power turbine total inlet pressure

R

rpm—revolutions per minute

RSG—readiness support group

RTD—resistance temperature detector

RTE—resistance temperature element

S

SAT—Scholastic Aptitude Test

SCC—ship control console

S/CE—signal conditioning enclosure

SDI—ship drawing index

SIMA—shore intermediate maintenance activity

SORM—Standard Organization and Regulationsof the U.S. Navy

SS—ship’s service

SSAS—ship’s service air system

SSDG—ship’s service diesel generator

SSGTG—ship’s service gas turbine generator

SSS—synchro-self-shifting

SWBD—switchboard

T

TIT—turbine inlet temperature

TLI—tank level indicator

TRAMAN—training manual

TSP—trisodium phosphate

T5.4—power turbine inlet temperature

U

UPS—uninterruptible power supply

UV—ultraviolet

V

vom—volt-ohm-milliammeter

W

WHB—waste-heat boiler

AII-4

APPENDIX III

ELECTRICAL SYMBOLS

AIII-1

AIII-2

AIII-3

APPENDIX IV

PIPING PRINT SYMBOLS

AIV-1

AIV-2

AIV-3

APPENDIX V

METRIC SYSTEM

Table AV-1.—Decimal System Prefixes

AV-1

293.80

Table AV-2.—Metric Conversions

AV-2

Table AV-3.—Metric Conversions—Continued

AV-3

Table AV-4.—Metric Conversions—Continued

AV-4

APPENDIX VI

LIST OF NAVY ELECTRICITY ANDELECTRONICS TRAINING SERIES

Module 1

Module 2

Module 3

Module 4

Module 5

Module 6

Module 7

Module 8

Module 9

Module 10

Module 11

Module 12

Module 13

Module 14

Module 15

Module 16

Module 17

Module 18

Module 19

Module 20

Module 21

Module 22

Introduction to Matter, Energy, and Direct Current

Introduction to Alternating Current and Transformers

Introduction to Circuit Protection, Control, and Measurement

Introduction to Electrical Conductors, Wiring Techniques, and Schematic Reading

Introduction to Generators and Motors

Introduction to Electronic Emission, Tubes, and Power Supplies

Introduction to Solid-State Devices and Power Supplies

Introduction to Amplifiers

Introduction to Wave-Generation and Wave-Shaping Circuits

Introduction to Wave Propagation, Transmission Lines, arid Antennas

Microwave Principles

Modulation Principles

Introduction to Number Systems and Logic Circuits

Introduction to Microelectronics

Principles of Synchros, Servos, and Gyros

Introduction to Test Equipment

Radio-Frequency Communications Principles

Radar Principles

The Technician’s Handbook

Master Glossary and Index

Test Methods and Practices

Introduction to Digital Computers

AVI-1

A

Abbreviations and acronyms, AII-1 to AII-4Administration and programs, 2-1 to 2-32

engineering administration, 2-3 to 2-32standing/night orders, 2-4 to 2-5EDORM, 2-3 to 2-4Engineering Operational Sequencing

System, 2-26 to 2-32EOSS User’s Guide, 2-27engineering operational casualty

control, 2-32engineering operational pro-

cedures, 2-27 to 2-32logs and records, 2-5 to 2-9

Automatic Bell Log, 2-9Engineering Log, 2-5 to 2-8Engineer’s Bell Book, 2-8 to 2-9equipment operating logs, 2-9

Main Space Fire Doctrine, 2-26personnel qualification standards,

2-25 to 2-26programs, 2-9 to 2-25

environmental quality, 2-25equipment tag-out program, 2-15

to 2-18fluid management program, 2-19

to 2-24gauge calibration, 2-25personnel protection programs,

2-18 to 2-19physical security program, 2-24

to 2-25Safety Program, 2-9 to 2-15valve maintenance, 2-25

Ship’s Maintenance and MaterialManagement (3-M) Systems, 2-2 to 2-3

benefits of PMS, 2-3Current Ship’s Maintenance Project,

2-3limitations of PMS, 2-3purposes of PMS, 2-3

Administration and programs-Continuedsources of information, 2-1 to 2-2

drawings, 2-2manufacturers’ technical manuals,

2-2Naval Sea Systems Command

publications, 2-1 to 2-2Advancement requirements, 1-1 to 1-3A.E.L. contaminated fuel detector MK III,

3-25A.E.L. free water detector MK II, 3-24

to 3-25Air compressors, 7-17 to 7-25Ammeters, 5-19Antifriction bearings, 10-6 to 10-7Automatic Bell Log, 2-9Automatic bus transfers (ABTs), 9-17 to 9-18

B

Batteries, 10-12 to 10-17Bearings, 8-6 to 8-8, 10-6 to 10-8Bellows element, 5-12 to 5-13Bernoulli’s principle, 4-10 to 4-11Bimetallic expansion thermometer, 5-2 to 5-3Bimetallic steam traps, 6-14Blowdown valves, 7-33Boiler construction, 7-28 to 7-32Boiler water/feedwater, 2-23 to 2-24Bolted flange joints, 6-30Borescope, 3-17 to 3-20Bourdon-tube elements, 5-10 to 5-12Boyle’s law, 4-9Brake/clutch assembly (DD and DDG class

ships), 8-8 to 8-10Brushes, 10-8Bulkhead seals, 8-45 to 8-47Bull gear, 8-6

C

Calipers, 3-11 to 3-13Centrifugal pumps, 7-2 to 7-8Centrifuge, 3-22 to 3-23

INDEX-1

INDEX

Chain hoists, 3-30Charles’s law, 4-9Check valves, 6-4 to 6-5Chemical treatment tank, 7-33Circuit breaker maintenance, 10-9 to 10-11Circuit breakers, 9-12 to 9-16Command career counselor, 1-7Condensate collecting system, 7-34 to 7-36Cone or in-line filter, 6-21Contact level sensors, 5-18Contaminated drain inspection, 7-34Control circuit analysis, 10-12Control oil servo valve, 8-42 to 8-43Control valves manifold block assembly,

8-36Controllable pitch propeller systems, 8-30 to

8-44control valves manifold block assembly,

8-36electronic pitch control system, 8-41 to

8-44hub/blade assembly, 8-31 to 8-34hydraulic oil power system, 8-36 to 8-41oil distribution box, 8-34 to 8-36valve rod assembly, 8-34

Controllable reversible pitch hydraulic pump,8-22

Controller troubleshooting, 10-11 to 10-12Coulomb’s law, 4-2Cranes, 3-32Current Ship’s Maintenance Project, 2-3Curved or conical spring lockwashers, 6-39

D

DD, DDG, and CG lube oil systems, 8-13 to8-16

Deadweight tester/gauge comparator, 3-16 to3-17

Deaerating feed tank, 7-34 to 7-36Dehumidifier, 8-23Dehydrators, 7-25 to 7-27Disassembly and reassembly of motors and

generators, 10-8 to 10-9Disc-type purifier, 7-15Divisional training petty officer, 1-6Drawings, 2-2Duplex filters, 6-19

E

EDORM, 2-3 to 2-4Educational guidance, 1-6 to 1-7Electrical distribution, 9-6 to 9-16

Electrical indicating instruments, 5-19 to5-21

Electrical pressure measuring instruments(transducers), 5-13 to 5-16

Electrical symbols, AIII-1 to AIII-3Electrical temperature measuring devices, 5-4

to 5-8resistance temperature detectors, 5-4 to

5-5resistance temperature elements, 5-5 to

5-6thermocouples, 5-6 to 5-8

Electrical theory and mechanical theory, 4-1to 4-20

electrical theory, 4-1 to 4-8electrical power generation, 4-3 to

4-8left-hand rule for generators, 4-8methods of producing electrical

power, 4-4 to 4-8laws, 4-1 to 4-3

Coulomb’s law, 4-2Kirchhoff’s voltage law, 4-1 to

4-2law of magnetism, 4-2 to 4-3Ohm’s law, 4-1

levers/leverage, 4-15 to 4-16first-class levers, 4-15 to 4-16second-class levers, 4-16third-class levers, 4-16

measurement of temperature, 4-17 to 4-19mechanical theory, 4-8 to 4-15

energy, 4-11 to 4-15energy transformation, 4-14 to

4-15mechanical energy, 4-11 to 4-13thermal energy, 4-13 to 4-14

laws and principles, 4-8 to 4-11Bernoulli’s principle, 4-10 to

4-11Boyle’s law, 4-9Charles’s law, 4-9Newton’s laws, 4-9 to 4-10Pascal’s law, 4-10

pressure definitions, 4-19 to 4-20Electrolyte, mixing, 10-13Electronic digital multimeters, 3-27Electronic pitch control system, 8-41 to 8-44Electrostatic vent fog precipitator, 8-22Energy, 4-11 to 4-15Engineering administration, 2-3 to 2-32

EDORM, 2-3 to 2-4Engineering Operational Sequencing

System, 2-26 to 2-32logs and records, 2-5 to 2-9

INDEX-2

Engineering administration—ContinuedMain Space Fire Doctrine, 2-26personnel qualification standards, 2-25 to

2-26programs, 2-9 to 2-25standing/night orders, 2-4 to 2-5

Engineering electrical equipment, 9-1 to 9-23generators and motors, 9-1 to 9-6

generators, 9-1 to 9-2motors, 9-2 to 9-6

polyphase motors, 9-2 to 9-4single-phase motors, 9-4 to 9-6

lead-acid sotrage batteries, 9-2360-hertz distribution system components,

9-6 to 9-23motor controllers, 9-20 to 9-23

low-voltage protection, 9-21low-voltage release, 9-21low-voltage release effect, 9-21magnetic across-the-line con-

trollers, 9-21overload relays, 9-22 to 9-23two-speed control, 9-21types of master switches, 9-20

power distribution components, 9-16to 9-19

automatic bus transfers, 9-17 to9-18

manual bus transfers, 9-18transformers, 9-18 to 9-19

power panels and cable markings,9-19 to 9-20

switchboards and panels, 9-6 to 9-16circuit breakers, 9-12 to 9-16control section, 9-7 to 9-10distribution section, 9-11power panels, 9-11shore power, 9-11 to 9-12

summary, 9-23uninterruptible power supply, 9-23

Engineering electrical equipment maintenance,10-1 to 10-17

circuit breaker maintenance, 10-9 to 10-11controller troubleshooting, 10-11 to 10-12

control circuit analysis, 10-12power circuit analysis, 10-11 to 10-12

lead-acid storage batteries, 10-12 to 10-17capacity, 10-14charging rate, 10-15charging time, 10-15gassing, 10-16 to 10-17mixing electrolyte, 10-13rating, 10-14

Engineering electrical equipment maintenance—Continued

lead-acid storage batteries—Continuedreadings when charged and discharged,

10-14specific gravity, 10-12 to 10-13

adjusting specific gravity, 10-13correcting specific gravity, 10-13measuring specific gravity, 10-12

to 10-13state of charge, 10-16test discharge, 10-15 to 10-16treatment of spilled acid, 10-13 to

10-14types of charges, 10-14 to 10-15

emergency charge, 10-15equalizing charge, 10-15floating charge, 10-15initial charge, 10-14normal charge, 10-14 to 10-15

motors and generators, 10-5 to 10-9bearings, 10-6 to 10-8

antifriction bearings, 10-6 to10-7

friction bearings, 10-7 to 10-8brushes, 10-8

brush care, 10-8correct brush type, 10-8

cleaning motors and generators,10-5 to 10-6

disassembly and reassembly ofmotors and generators, 10-8 to 10-9

wire wrapping, 10-1 to 10-5wire-wrap principles, 10-1wire-wrap techniques, 10-1 to 10-5

advantages, 10-4disadvantages, 10-4 to 10-5

Engineering Log, 2-5 to 2-8Engineering Operational Sequencing System,

2-26 to 2-32Engineering Support and Auxiliary Equip-

ment, 7-1 to 7-38air compressors, 7-17 to 7-25

classification of air compressors, 7-18to 7-24

high-pressure air compressors,7-22 to 7-24

low-pressure or ship’s service aircompressors, 7-18 to 7-22

maintenance of air compressors, 7-24safety precautions, 7-24 to 7-25

INDEX-3

Engineering Support and Auxiliary Equip-ment—continued

dehydrators, 7-25 to 7-27desiccant air dehydrator (type II),

7-26 to 7-27refrigeration air dehydrator (type I),

7-25 to 7-26refrigeration and desiccant air

dehydrator (type III), 7-27oily-water separator, 7-36 to 7-38pumps, 7-1 to 7-13

alignment of shaft and coupling,7-11 to 7-13

classification of pumps, 7-2 to 7-11centrifugal pumps, 7-2 to 7-8jet pumps, 7-10 to 7-11rotary pumps, 7-8 to 7-10

purifiers, 7-13 to 7-17general notes on purifier operations,

7-17purifier classification, 7-13 to 7-17

disc-type purifier, 7-15tubular-type purifier, 7-16 to

7-17purifier operation, 7-13

waste-heat boiler, 7-27 to 7-36boiler classification, 7-28boiler construction, 7-28 to 7-32

boiler control panel, 7-31 to 7-32casing, 7-29control condenser, 7-31recirculation pump, 7-31steam separator/water reservoir,

7-30 to 7-31tube bundle, 7-29

feedwater control valve, 7-33miscellaneous components, 7-33 to

7-36blowdown valves, 7-33chemical treatment tank, 7-33condensate collecting system,

7-34 to 7-36soot blowers, 7-33 to 7-34

steam pressure control, 7-32 to 7-33steam dump valve, 7-33steam stop valve, 7-33

Engineer’s Bell Book, 2-8 to 2-9Environmental quality, 2-25Equipment operating logs, 2-9Equipment tag-out program, 2-15 to 2-18

F

Fasteners, 6-37 to 6-40locknuts, 6-38 to 6-39lockwashers, 6-39 to 6-40threaded locking devices, 6-37

Feedwater and drain collecting tank, 7-34Feedwater control valve, 7-33FFG lube oil system, 8-16 to 8-17Filled-system thermometers, 5-3 to 5-4Filters and strainers, 6-15 to 6-21

construction of filter elements, 6-18to 6-19

filter/strainer location, 6-17 to 6-18filter/strainer materials, 6-18filters, types of, 6-19 to 6-21mesh and micron ratings, 6-15 to 6-17

First-reduction gears, 8-5Fittings, 6-29 to 6-32

bolted flange joints, 6-30flared fittings, 6-30 to 6-31flareless fittings, 6-32silver-brazed joints, 6-30threaded joints, 6-29unions, 6-30welded joints, 6-30

Flange safety shields, 6-32Flared fittings, 6-30 to 6-31Flareless fittings, 6-32Flexible hose assemblies, 6-24 to 6-29Fluid management program, 2-19 to 2-24Frequency counters, 3-28Frequency meters, 5-20Friction bearings, 10-7 to 10-8Fuel oil (F-44, JP-5), 2-21 to 2-23Fuel oil (F-76, Navy distillate), 2-20 to 2-21Full-flow filters, 6-19

G

Gaskets, 6-33Gassing, 10-16 to 10-17Gauge calibration, 2-25Gear casing, 8-4Gear pumps, 7-9Generators, 9-1 to 9-2, 10-5 to 10-9Glossary, AI-l to AI-15Grinding-in valves, 6-12

H

Hand tools, 3-1 to 3-8inspection mirror, 3-7mechanical fingers, 3-6 to 3-7screw and tap extractors, 3-6

INDEX-4

Hand tools—Continuedtaps and dies, 3-4 to 3-5thread chasers, 3-5 to 3-6wire-twister pliers, 3-1 to 3-3wire-wrap hand tools, 3-8wrenches, 3-3 to 3-4

Hand-operated ratchet lever hoists, 3-30 to3-31

Heat exchangers, 6-21 to 6-24Heat gun, 3-17Helical spring lockwashers, 6-39High-pressure air compresssors, 7-22 to 7-24High-speed pinions, 8-5Hoisting and lifting devices, 3-30 to 3-32

chain hoists, 3-30cranes, 3-32hand-operated ratchet lever hoists, 3-30

to 3-31push-pull hydraulic jack, 3-31 to 3-32

Hub/blade assembly, 8-31 to 8-34Hydraulic oil power system, 8-36 to 8-41Hydrometer, 3-28 to 3-30Hydrostatic testing, 6-27

I

Ice detector system, 5-21 to 5-22In-line or cone filter, 6-21Indicating filters, 6-20Indicating instruments, 5-1 to 5-26

electrical indicating instruments, 5-19to 5-21

ammeters, 5-19frequency meters, 5-20kilowatt meters, 5-20phase-sequence indicators, 5-21synchroscopes, 5-20 to 5-21voltmeters, 5-19

liquid level indicators, 5-17 to 5-18contact level sensors, 5-18tank level indicators, 5-17 to 5-18

miscellaneous sensors, 5-21 to 5-25ice detector system, 5-21 to 5-22

ice-detector signal conditioners,5-22

ice detectors, 5-21 to 5-22speed sensors, 5-22 to 5-23

magnetic speed pickup transducer,5-22 to 5-23

tachometer generators, 5-22ultraviolet flame detector, 5-25

flame detector, 5-25flame-detector signal conditioner,

5-25vibration sensors, 5-23 to 5-25

Indicating instruments—Continuedpressure measuring instruments, 5-9 to

5-17electrical pressure measuring

instruments (transducers), 5-13to 5-16

pressure transducer calibration,5-13 to 5-16

pressure transducer operation,5-13

mechanical pressure measuringinstruments, 5-10 to 5-13

bellows element, 5-12 to 5-13bourdon-tube elements, 5-10 to

5-12pressure switches, 5-16 to 5-17

construction of pressure switches,5-16

setting pressure switches, 5-17temperature measuring instruments, 5-1

to 5-9electrical temperature measuring

devices, 5-4 to 5-8resistance temperature detectors,

5-4 to 5-5resistance temperature elements,

5-5 to 5-6thermocouples, 5-6 to 5-8

mechanical temperature measuringdevices, 5-1 to 5-4

bimetallic expansion thermometer,5-2 to 5-3

filled-system thermometers, 5-3to 5-4

liquid-in-glass thermometers, 5-2temperature switches, 5-8 to 5-9

adjustments, 5-9construction, 5-8 to 5-9

Inlet filters and strainers, 6-17Input shafts, 8-4Inspection mirror, 3-7Insulation, 6-40 to 6-41

J

Jam nuts, 6-38Jet pumps, 7-10 to 7-11Journal bearings, 8-6 to 8-7

K

Kilowatt meters, 5-20Kirchhoff’s voltage law, 4-1 to 4-2

INDEX-5

L

Lapping valves, 6-12 to 6-13Law of magnetism, 4-2 to 4-3Lead-acid storage batteries, 9-23, 10-12

to 10-17Leadership, management, and education

training school, 1-3 to 1-5Levers/leverage, 4-15 to 4-16Liquid level indicators, 5-17 to 5-18Liquid-in-glass thermometers, 5-2List of Navy Electricity and Electronics

Training Series, AVI-1Locknuts, 6-38 to 6-39Lockwashers, 6-39 to 6-40Logs and records, 2-5 to 2-9

Automatic Bell Log, 2-9Engineering Log, 2-5 to 2-8Engineer’s Bell Book, 2-8 to 2-9equipment operating logs, 2-9

Low-pressure or ship’s service air compressors,7-18 to 7-22

Low voltage protection, 9-21Low voltage release, 9-21Lube oil system (DD, DDG, and CG), 8-20 to

8-21, 8-13 to 8-16Lube oil system (FFG), 8-16 to 8-17, 8-20

to 8-21Lubricating pump, 8-20 to 8-22

Magnetic speedto 5-23

Main reduction

M

pickup transducer, 5-22

gear (DD, DDG, and CGclass ships), 8-1 to 8-30

Main Space Fire Doctrine, 2-26Main thrust bearings, 8-7 to 8-8Manual bus transfers (MBTs), 9-18Manufacturers’ technical manuals, 2-2Measurement of temperature, 4-17 to 4-19Mechanical energy, 4-11 to 4-13Mechanical fingers, 3-6 to 3-7Mechanical pressure measuring instruments,

5-10 to 5-13Mechanical seals, 7-5Mechanical steam traps, 6-13 to 6-14Mechanical temperature measuring devices,

5-1 to 5-4bimetallic expansion thermometer, 5-2 to

5-3filled-system thermometers, 5-3 to 5-4liquid-in-glass thermometers, 5-2

Mechanical theory, 4-8 to 4-15energy, 4-11 to 4-15laws and principles, 4-8 to 4-11

Megohmmeter, 3-27Mesh and micron ratings, 6-15 to 6-17Metric system, the, AV-1 to AV-4Micrometer, 3-13 to 3-16Motor controllers, 9-20 to 9-23Motors, 9-2 to 9-6Motors and generators, 10-5 to 10-9MRG instrumentation, 8-24 to 8-25Multimeters, 3-26 to 3-27

N

Naval Sea Systems Command publications,2-1 to 2-2

Naval Ship’s Technical Manual (NSTM), 2-2Newton’s laws, 4-9 to 4-10Nylon insert nuts, 6-38

O

O-rings, 6-36 to 6-37OD box-mounted potentiometers, 8-43 to 8-44Ohm’s law, 4-1Oil distribution, 8-13 to 8-17Oil distribution box, 8-34 to 8-36Oil spills, 2-20Oily-water separator, 7-36 to 7-38Orifice steam traps, 6-14Oscilloscopes, 3-27 to 3-28Overload relays, 9-22

P

Packing and gaskets, 6-33Pascal’s law, 4-10Pensky-Martens closed-cup flash point tester,

3-23Personnel protection programs, 2-18 to 2-19Personnel qualification standards, 2-25 to 2-26Phase-sequence indicators, 5-21Physical security program, 2-24 to 2-25Piping print symbols, AIV-1 to AIV-3Piping system components, 6-1 to 6-43

fasteners, 6-37 to 6-40locknuts, 6-38 to 6-39

jam nuts, 6-38nylon insert nuts, 6-38plastic ring nuts, 6-38spring beam nuts, 6-39spring nuts, 6-38 to 6-39

INDEX-6

Piping system components—Continuedfasteners—Continued

lockwashers, 6-39 to 6-40curved or conical spring lock-

washers, 6-39helical spring lockwashers, 6-39toothed lockwashers, 6-39 to

6-40threaded locking devices, 6-37

length of protrusion, 6-37repair of damaged threads, 6-37

filters and strainers, 6-15 to 6-21construction of filter elements, 6-18

to 6-19filter/strainer location, 6-17 to 6-18

inlet filters and strainers, 6-17pressure line filters, 6-17return line filters, 6-18

filter/strainer materials, 6-18filters, types of, 6-19 to 6-21

duplex filters, 6-19filter/separator, 6-20 to 6-21full-flow filters, 6-19indicating filters, 6-20in-line or cone filter, 6-21proportional-flow filters, 6-20simplex filter, 6-19

maintenance, 6-21mesh and micron ratings, 6-15 to 6-17

heat exchangers, 6-21 to 6-24classification of heat exchangers,

6-21 to 6-23direction of flow, 6-22 to 6-23number of passes, 6-23path of heat flow, 6-23type of construction, 6-22type of surface, 6-21 to 6-22

maintenance of heat exchangers, 6-23zincs, 6-23 to 6-24

insulation, 6-40 to 6-41general insulation precautions, 6-41insulation materials, 6-40removable insulation, 6-40

packing and gasket material, 6-33 to 6-37O-rings, 6-36 to 6-37packing of fixed joints, 6-35 to 6-36packing and gasket selection, 6-33 to

6-34packing of moving joints, 6-34 to 6-35

piping, 6-24 to 6-33fittings, 6-29 to 6-32

bolted flange joints, 6-30flared fittings, 6-30 to 6-31flareless fittings, 6-32silver-brazed joints, 6-30

Piping system components—Continuedpiping—Continued

fittings—Continuedthreaded joints, 6-29unions, 6-30welded joints, 6-30

flange safety shields, 6-32flexible hose assemblies, 6-24 to 6-29

air test, 6-27approved flexible hose con-

figurations, 6-25 to 6-26fitting identification, 6-26hose identification, 6-26hydrostatic test, 6-27inspection of hose and fittings

prior to make-up, 6-26installation of flexible hose

assemblies, 6-27 to 6-28periodic inspection by ship’s

force, 6-28service life of rubber hose, 6-29servicing, 6-29shelf life, 6-28 to 6-29storage, 6-28visual inspection, 6-26 to 6-27

identification of piping, 6-24inspections and maintenance, 6-32 to

6-33pipe hangers, 6-32piping materials, 6-24piping system identification marking,

6-33steam traps, 6-13 to 6-15

maintenance, 6-15types of steam traps, 6-13 to 6-14

bimetallic steam traps, 6-14mechanical steam traps, 6-13 to

6-14orifice steam traps, 6-14

valves, 6-1 to 6-13maintenance, 6-10 to 6-13

grinding-in valves, 6-12lapping valves, 6-12 to 6-13refacing valves, 6-13repacking valves, 6-13spotting-in valves, 6-12

valve construction, 6-1valve handwheel identification and

color coding, 6-10valve manifolds, 6-9 to 6-10valve types, 6-1 to 6-9

check valves, 6-4 to 6-5special-purpose valves, 6-5 to 6-9stop valves, 6-2 to 6-4

INDEX-7

Plastic ring nuts, 6-38Polyphase motors, 9-2 to 9-4Power circuit analysis, 10-11 to 10-12Power distribution components, 9-16 to 9-19Power panels and cable markings, 9-19 to 9-20Power supply, 3-26Power train and controllable pitch propeller,

8-1 to 8-49controllable pitch propeller systems, 8-30

to 8-44control valves manifold blockassembly, 8-36

electronic pitch control system, 8-41to 8-44

control oil servo valve, 8-42 to8-43

OD box-mounted potentiometers,8-43 to 8-44

hub/blade assembly, 8-31 to 8-34blade seal base ring, 8-32blades, 8-32hub body asembly, 8-31 to 8-32tail-shaft spigot, 8-32 to 8-34

hydraulic oil power system, 8-36 to8-41

hydraulic oil power module, 8-38oil distribution, 8-38 to 8-41

oil distribution box, 8-34 to 8-36valve rod assembly, 8-34

main reduction gear (DD, DDG, and CGclass ships), 8-1 to 8-30

attached equipment, 8-17 to 8-30controllable reversible pitch

hydraulic pump, 8-22dehumidifier, 8-23electrostatic vent fog precipitator,

8-22lubricating pump, 8-20 to 8-22MRG instrumentation, 8-24 to

8-25propeller shaft brakes, 8-28 to

8-30revolution counter and elapsed

time indicator, 8-24shaft tachometer, 8-23 to 8-24tachometer generator, revolution

counter, and magnetic speedsensor drive, 8-24

turbine brakes, 8-26 to 8-28turning gear motor assembly,

8-17 to 8-20bearings, 8-6 to 8-8

journal bearings, 8-6 to 8-7main thrust bearings, 8-7 to 8-8

Power train and controllable pitchpropeller—Continued

main reduction gear (DD, DDG, and CGclass ships)—Continued

brake/clutch assembly (DD andDDG class ships), 8-8 to 8-10

clutch sequencing, 8-8 to 8-10control air system, 8-8

bull gear, 8-6first-reduction gears, 8-5gear casing, 8-4high-speed pinions, 8-5input shafts, 8-4oil distribution, 8-13 to 8-17

DD, DDG, AND CG lube oilsystems, 8-13 to 8-16

FFG lube oil system, 8-16 to8-17

second-reduction pinions, 8-5synchro-self-shifting clutch, 8-11 to

8-13clutch disengagement, 8-12clutch engagement, 8-12lockout control, 8-12 to 8-13lubrication, 8-13

prairie air system, 8-44propulsion shafting system, 8-44 to 8-49

propulsion shaft seals, 8-45 to 8-49bulkhead seals, 8-45 to 8-47stern tube seals, 8-47 to 8-49

shaft bearings, 8-45stern tube bearings, 8-45strut bearings, 8-45

shafting, 8-44 to 8-45Prairie air system, 8-44Precision tools, 3-8 to 3-16

micrometer, 3-13 to 3-16simple calipers, 3-11 to 3-12slide calipers, 3-12torque wrenches, 3-8 to 3-11vernier caliper, 3-12 to 3-13

Pressure definitions, 4-19 to 4-20Pressure line filters, 6-17Pressure measuring instruments, 5-9 to 5-17

electrical pressure measuring instrumentstransducers), 5-13 to 5-16

mechanical pressure measuring instruments,5-10 to 5-13

pressure switches, 5-16 to 5-17Pressure switches, 5-16 to 5-17Pressure transducer calibration, 5-13 to 5-16Pressure transducer calibration kit, 3-22Pressure transducer operation, 5-13Propeller shaft brakes, 8-28 to 8-30Proportional-flow filters, 6-20

INDEX-8

Propulsion shafting, 8-44 to 8-49Pumps, 7-1 to 7-13Purifiers, 7-13 to 7-17Push-pull hydraulic jack, 3-31 to 3-32

R

Rating information, 1-1 to 1-7advancement requirements, 1-1 to 1-3

eligibility requirements for advance-ment, 1-2

exam and notification of results, 1-3professional development, 1-2 to 1-3

studying for advancement, 1-2 to1-3

sustained superior performance,1-2

duties and responsibilities, 1-1formation of the GSE/GSM ratings, 1-1training sources, 1-3 to 1-7

educational guidance, 1-6 to 1-7command career counselor, 1-7divisional training petty officer,

1-6educational services officer, 1-6

to 1-7schools, 1-3 to 1-5

leadership, management, andeducation training school, 1-3to 1-5

technical schools, 1-3training manuals, 1-5 to 1-6

Refacing valves, 6-13References, AVII-1 to AVII-7Refrigeration air dehydrator (type I), 7-25

to 7-26Refrigeration and desiccant air dehydrator

(type III), 7-27Repacking valves, 6-13Resistance boxes, 3-25Resistance temperature detectors, 5-4 to 5-5Resistance temperature elements, 5-5 to 5-6Return line filters, 6-18Revolution counter and elapsed time indicator,

8-24Rotary pumps, 7-8 to 7-10

S

Safety Program, 2-9 to 2-15Salinity indicating system, 7-34Schools, 1-3 to 1-5Screw and tap extractors, 3-6

Screw pumps, 7-9 to 7-10Second-reduction pinions, 8-5Shaft bearings, 8-45Shaft brakes, 8-28 to 8-30Shaft tachometer, 8-23 to 8-24Ships’ Maintenance and Material Management

(3-M) Systems, 2-2 to 2-3Shore power, 9-11Signal generators, 3-28Silver-brazed joints, 6-30Simple calipers, 3-11 to 3-12Simplex filter, 6-19Single-phase motors, 9-4 to 9-660-hertz distribution system components, 9-6

to 9-23motor controllers, 9-20 to 9-23power distribution components, 9-16 to

9-19power panels and cable markings, 9-19 to

9-20switchboards and panels, 9-6 to 9-16

Slide calipers, 3-12Sliding vane pumps, 7-10Soot blowers, 7-33 to 7-34Special-purpose valves, 6-5 to 6-9Specific gravity, 10-12 to 10-13Speed sensors, 5-22 to 5-23Spotting-in valves, 6-12Spring beam nuts, 6-39Spring nuts, 6-38 to 6-39Standing/night orders, 2-4 to 2-5Steam pressure control, 7-32 to 7-33Steam separator/water reservoir, 7-30Steam traps, 6-13 to 6-15Stern tube seals, 8-47 to 8-49Stop valves, 6-2 to 6-4Stroboscope, 3-17Switchboards and panels, 9-6 to 9-16Synchro-self-shifting clutch, 8-11 to 8-13Synchroscopes, 5-20 to 5-21

T

Tachometer generator, revolution counter,and magnetic speed sensor drive, 8-24

Tank level indicators, 5-17 to 5-18Taps and dies, 3-4 to 3-5Technical schools, 1-3

INDEX-9

Temperature measuring instruments, 5-1 to5-9

electrical temperature measuring devices,5-4 to 5-8

mechanical temperature measuring devices,5-1 to 5-4

temperature switches, 5-8 to 5-9Temperature switches, 5-8 to 5-9Test equipment, 3-16 to 3-30Thermal energy, 4-13 to 4-14Thermocouples, 5-6 to 5-8Thread chasers, 3-5 to 3-6Threaded joints, 6-29Threaded locking devices, 6-37Tools and test equipment, 3-1 to 3-32

hand tools, 3-1 to 3-8inspection mirror, 3-7mechanical fingers, 3-6 to 3-7screw and tap extractors, 3-6taps and dies, 3-4 to 3-5thread chasers, 3-5 to 3-6wire-twister pliers, 3-1 to 3-3wire-wrap hand tools, 3-8wrenches, 3-3 to 3-4

nonrecommended wrenches andhand tools, 3-4

recommended wrenches, 3-3 to3-4

hoisting and lifting devices, 3-30 to 3-32chain hoists, 3-30cranes, 3-32hand-operated ratchet lever hoists,

3-30 to 3-31push-pull hydraulic jack, 3-31 to 3-32

precision tools, 3-8 to 3-16micrometer, 3-13 to 3-16

reading a micrometer caliper,3-14 to 3-16

reading a vernier micrometercaliper, 3-16

selecting the proper micrometer,3-14

types of micrometers, 3-13 to3-14

simple calipers, 3-11 to 3-12slide calipers, 3-12torque wrenches, 3-8 to 3-11

proper use of torque wrenches,3-10 to 3-11

torque valves, 3-9 to 3-10types of torque wrenches, 3-9

vernier caliper, 3-12 to 3-13

Tools and test equipment-Continuedtest equipment, 3-16 to 3-30

A.E.L. contaminated fuel detectorMK III, 3-25

A.E.L. free water detector MK II,3-24 to 3-25

borescope, 3-17 to 3-20borescope use, 3-18 to 3-20function of the borescope, 3-17

to 3-18centrifuge, 3-22 to 3-23deadweight tester/gauge comparator,

3-16 to 3-17electronic digital multimeters, 3-27frequency counters, 3-28heat gun, 3-17hydrometer, 3-28 to 3-30megohmmeter, 3-27multimeters, 3-26 to 3-27oscilloscopes, 3-27 to 3-28Pensky-Martens closed-cup flash

point tester, 3-23power supply, 3-26pressure transducer calibration kit,

3-22resistance boxes, 3-25signal generators, 3-28stroboscope, 3-17ultraviolet test unit, 3-17vibration analysis, 3-20 to 2-22

vibration analyzers, 3-21 to 3-22vibration meter, 3-21

Toothed lockwashers, 6-39 to 6-40Torque wrenches, 3-8 to 3-11Training sources, 1-3 to 1-7

educational guidance, 1-6 to 1-7schools, 1-3 to 1-5training manuals, 1-5 to 1-6

Transformers, 9-18 to 9-19Tubular-type purifier, 7-16 to 7-17Turbine brakes, 8-26 to 8-28Turning gear motor assembly, 8-17 to

8-20

U

Ultraviolet flame detector, 5-25Ultraviolet test unit, 3-17

INDEX-10

Uninterruptible power supply, 9-23Unions, 6-30

V

Valve maintenance, 2-25Valve rod assembly, 8-34Valves, 6-1 to 6-13

maintenance, 6-10 to 6-13valve construction, 6-1valve handwheel identification and color

coding, 6-10valve manifolds, 6-9 to 6-10valve types, 6-1 to 6-9

Vernier caliper, 3-12 to 3-13Vibration analysis, 3-20 to 3-22

Vibration sensors, 5-23 to 5-25Voltmeters, 5-19

W

Waste-heat boiler, 7-27 to 7-36Waste heat boiler treatment, 2-24Welded joints, 6-30Wire wrapping, 10-1 to 10-5Wire-twister pliers, 3-1 to 3-3Wire-wrap hand tools, 3-8Wrenches, 3-3 to 3-4

Z

Zincs, 6-23 to 6-24

INDEX-11