permit-required confined space entry 29 cfr 1910.146

Permit-Required ConfinedSpace Entry

29 CFR 1910.146

Objectives

• Understand Legislation Developed by

Government Agencies

• Identify and Use Those Regulations

• Identify a Potentially Hazardous Confined Space

Organizations• ANSI

–American National Standards Institute–Consensus Standards for Atmospheric Hazards

• NIOSH–National Institute for Occupational Safety and Health–Documents Incidents–Develops Guidelines for Safe Work

Organizations(continued)

• OSHA

–Occupational Safety and Health Administration

–Began Looking at Confined Spaces in 1975

–Cited Under General Duty Clause

–Proposed Standard Released June 1989

Permit-Required Confined Spaces29 CFR 1910.146

• Became Law April 15, 1993• Employers MUST

–Characterize the Confined Space–Provide a Permit Allowing Entry–Supply Personal Protective Equipment When

Required

• Excludes Agriculture, Construction, and Shipyards


• Large Enough and Configured Such That an Employee

Can Enter and Perform Assigned Work

• Has Limited or Restricted Means for Entry or Exit (e.g.,

Tanks, Vessels, Silos, Storage Bins, Hoppers, Vaults, and Pits)

• Is Not Designated for Continuous Employee Occupancy

A Confined Space is...


• Contains or Has Potential to Contain a Hazardous Atmosphere

• Contains a Material That Has the Potential for Engulfment

• Internal Configuration of Inwardly Converging Walls or Sloping

and Tapering Floor

• Contains Any Other Recognized Serious Safety or Health Hazard

A Permit-Required Confined Space...


• Surrounding and Capture of a Person• Liquid or Finely Divided (Flowable) Solid• Can Cause Filling or Plugging of Respiratory

System Via Aspiration• Can Exert Enough Force on Body to Cause Death

by Strangulation, Constriction, or Crushing

Engulfment...


• Immediate or Delayed Threat to Life• Causes Irreversible Adverse Health Effects• Interferes With the Ability to Escape from a

Permit Space

Immediately Dangerous to Life or Health (IDLH)...


• Flammable Gas, Vapor, or Mist >10% of LFL (LEL)

• Airborne Combustible Dust > LFLDust Obscures Vision at a Distance of 5 ft. or less

• Oxygen < 19.5 % or > 23.5%• Exposures in Excess of OSHA’s PELs

IDLH Conditions...

Employer’s Responsibilities

• Determines Whether Permit-Required Confined Spaces Exist(Appendix A - Flow Chart)

• Informs Employees and Posts Warning Signs• Prevents Entry If Employees are Not to Work in

PRCS

Employer’s Responsibilities(continued)

• Develop and Implement a Written Permit Entry Program

• May Use Alternate Procedures• If a Non-Permit Space is Reconfigured, Re-

evaluation of the Space is Required• Must Inform Contractors and Use Permitting

Program

DANGER

CONFINED SPACE

ENTER BY PERMIT ONLY!

Permit-Required Confined SpaceELEMENTS OF THE PROGRAM

• Prevent Unauthorized Entry• Identify and Evaluate the Hazards Prior to Entry

(Appendix B- Who Can Do This, & How)

• Develop Safe Entry Procedures– Acceptable Entry Conditions– Isolating the Permit Space– Purging, Inerting, Flushing, or Ventilating– Barriers to Protect from External Hazards

Permit-Required Confined Space(PRCS)

• Testing and Monitoring Equipment

• Ventilating Equipment

• Communications Equipment

• Personal Protective Equipment

Equipment


• Lighting

• Barriers and Shields

• Ladders and Other Entry/Egress Equipment

• Rescue and Emergency Equipment

Equipment (continued)


(continued)• Evaluate Space Before and During Work• Provide at Least One Attendant Outside for the

Duration of Entry Operations• Multiple Space Response Procedures• Designate Active Roles• Rescue and Emergency Response Procedures


(continued)• System for Preparation, Issuance, Use and

Cancellation of Permits• Procedures for Multiple Employer Worksites• Procedures for Closing Space• Review of Entry Operations• Review of Program


• Permit System• Entry Permit• Training• Other Appendices

–Appendix C: Example Situations–Appendix D: Example Check List & Permit–Appendix E: Sewer System Entry

Permit-Required Confined SpaceThe Permit

1. DATE:____ TIME:____ A.M../P.M. 2. VESSEL # 3. JOB # 4. LOCATION:

5.DESCRIPTION OF WORK:

6.PHYSICAL HAZARD ASSESSMENT: Engulfment, Electrical, Steam, Augers, Chain Drives etc..

7. CORRECTIVE MEASURES: Physical Disconnects, Lockout / Tagout etc..

8. ATMOSPHERIC ASSESSMENT: Oxygen, LEL, CO, H2S (Other)

9. Instrument # 10. Calibration Date: 11. Name of Operator:

12. Substance 13. P.E.L. 14. Actual

15. Oxygen 16. < 19.5% or > 23.5% 17. Other

18. LEL > 10% 20.

21. Carbon Monoxide (CO) 22. 50 ppm 23. Other

24. Hydrogen Sulphide (H2S) 25. 10 ppm 26. Other

27. PPE 28. Respirators 29.Rescue Equipment

30. Other 31. Other 32. Other

33. Names of entrants, Attendants, and Entry Supervisors:

34. Time work / shift completed: (35.) Problems / concerns

36. Emergency contact:

Other OSHA Regulations

Hazard Communication

–29 CFR 1926.59–MSDS–Training–Labeling–Written Program

Control of Hazardous Energy Sources–29 CFR 1926.417 & 1910.147

–“Lock Out/Tag Out”

–De-Energize ALL Sources of Energy

–Written Program

Permit-Required Confined Spaces

Administrative Controls

Permit Space Entry Program

Learning Objectives

• Describe the Guidelines for a Permit-Required Confined Space Program

• Identify Conditions Which Allow the Use of Alternate Procedures

General Requirements

• A Written Permit Space Program• Authorized Personnel• Confined Space Evaluation Procedures• Acceptable Entry Conditions and Procedures

PRCS ProgramThe Entry Permit Shall Identify:

1) The Permit Space to be Entered.2) The Purpose of the Entry.3) The Date and Duration.4) The Authorized Entrants.5) The Attendants.6) The Entry Supervisor.7) The Hazards of the Space to be Entered.8) Measures to Isolate and Eliminate the Hazards Before Entry.

9) The Acceptable Entry Conditions.

10) The results of Initial and Periodic Tests with Initials of

Testers.

PRCS ProgramThe Entry Permit Shall Identify:

11) The Rescue and Emergency Services That Can Be

Summoned.

12) The Communication Procedures Used By Entrants and

Attendants.

13) Equipment such as Testing, Communication and

Emergency Equipment.

14) Any Other Information Necessary, In Order To Ensure

Employee Safety.

15) Any Additional Permits Such As a Hot Work Permit.

Authorized Entrant Duties

• Knows Hazards, Symptoms, and Consequences

• Proper Use of Equipment

• Communicate With Attendant

• Exit Promptly From PRCS When Necessary

Attendant Duties• Knows Hazards, Symptoms, and Consequences

• Awareness of Behavioral Effects of Exposure

• Continuously Identifies Number and Identity of Entrants

• Remains Outside of PRCS

• Communicates With Entrants

Attendant Duties

• Monitors Entrant & Surrounding Activity• Summons Rescue If Needed• Keeps Unauthorized Persons Away From PRCS• Performs Non-Entry Rescues• Performs Only Attendant Duties

Entry Supervisor Duties

• Knows Hazards, Symptoms, and Consequences

• Verifies Performance of Permit Testing, Procedures and Equipment

• Terminates PRCS Entry and Permit

Entry Supervisor Duties

• Verifies Availability and Communication With Rescue Services

• Removes Unauthorized Personnel• Determines Compliance With the Entry

Permit

Rescue and Emergency Services

• Trained in PPE and Rescue Equipment• Trained in Rescue and Authorized Entrant Duties• Practice Rescues Once Every 12 Months

– Simulated With Mannequins or People– In Actual PRCS

• Trained in CPR and Basic First Aid–At Least 1 Member of Rescue Service Holding Current

Certification

Using Employer’s Personnel...


• Must Be Informed of Hazards Prior to Arrival

• Must Have Access to All Spaces to Assess and Allow for Practice of Rescues

Outside Rescue Service...


“Retrieval Systems or Methods Shall Be Used Whenever an Authorized Entrant Enters a PRCS”– Unless Equipment Increases Risk or Would Not Assist Rescue

– Chest or Full Body Harness, Center of Back Near Shoulder or Above

Head; Wristlets ONLY if Harness is Infeasible or Greater Hazard

– Attached to Mechanical Device or Fixed Point Outside Space

– MSDS Must Be at Worksite and Furnished to Medical Facility Treating

Exposed Entrants

Non-Entry Rescue...

Testing and MonitoringAppendix B

• Evaluation Testing–Any Hazards–Prior to Entry– Technically Qualified Professional

• OSHA Consultation Service• CIH• Registered Safety Engineer• CSP

• Verification Testing

Testing and MonitoringAppendix B

• Duration of Testing

• Testing Stratified Atmospheres–Atmospheric Envelope of 4 ft. in Direction of Travel

and to All Sides–Rate of Progress of Entrant Slowed to Accommodate

Instrument Sampling Speed and Response Time

Hot Work PermitsDefined As: Written Authorization to Perform

Operations Capable of Providing a Source of Ignition (Such As Welding, Cutting, or Brazing)

Required for: Hot Work in Grain Handling Facilities and Any Other Combustible/ Explosive Areas

Hot Work PermitsGeneral Provisions

• Remove Fire Hazards & Combustibles• Guard the Work• Guard Openings to Other Areas• Maintain Fire Extinguishers

Hot Work PermitsGeneral Provisions

• Maintain Fire Watch• Written Permit Authorization• Protect Floors & Walls• Protect Drains, Dusts, and Pipes

Alternate Procedures

• ONLY Hazard is an Actual or Potential Hazardous Atmosphere

And• Can Demonstrate That Continuous Forced Air is

Sufficient to Maintain the Space as Safe• Data is Developed to Support the Above• A Permit Program is Followed During Data

Collection

Can be used if...

Alternate Procedures(continued)

• Hazard from Removing Entrance Cover is Eliminated

• Entrance is Made Safe to Prevent Accidental Falls• Atmospheric Testing for

– Oxygen– Flammability– Toxic Contaminants


• No Hazardous Atmospheres Develop While Employee is In Space

• Continuous Forced Air Ventilation is Used–No Entry Until Safe–Remains Until Everyone Has Left Space–Air is From a Clean, Safe Source

• Periodic Testing


• If A Hazard Develops–Evacuation of Space–Evaluation as to the Source–Protection of Employees Prior to Re-entry

• Documentation–Date, Location, Signature of Person Certifying–Certification Made Prior to Entry and Available to

each Employee

• If the Stated Conditions Are Met, the Employer Does Not Have to Implement

• OSHA Compliance Letter (10/12/95) Interprets the Elimination Provision: “… If the Non-Atmospheric Hazards Were Permanently Eliminated, the Alternate Procedures Could Subsequently Be Applied…”


At Issue -“Elimination” of Hazards

–PRCS Program–Permit System–Entry Permit

–Personnel Duties–Rescue–Emergency Services

Hazards are usually dictated by...

• The material stored in the confined space.

• The activity carried out in the confined space. (a particular chemical reaction)

• The external environment. (a tank located near rising waters)

OSHA Estimates• 224,000 establishments have permit required

confined space.

• 2.1 million workers enter these spaces annually.

• 60% of the deaths that occur in confined spaces are the rescuers who go in after the victim.

Confined Space Hazards• Chemical Hazards

• Physical Hazards

• Biological Hazards

• Ergonomic Hazards

Engulfment

• The surrounding or covering of a person by a liquid or flowable solid. Death may result by suffocation, strangulation, constriction, or crushing.– Concrete– Asphalt

Primary Constituents of Normal Air(Permanent Gases)

ConstituentChemicalFormula

MolecularWeight

Percentby Volume

Nitrogen

Oxygen

Argon

N2

O2

Ar

28

32

40

78.1

20.9

0.9

Water vapor content varies, but is usually the third largest constituent by volume in air.

Definitions of O2 Deficient Atmosphere

Source Oxygen Content

29 CFR 1910.146 (PRCS) <19.5%

42 CFR Part 84 (NIOSH Resp. Approval) <19.5%

29 CFR 1910.134(g) (Resp. Std.) 16.0%1

29 CFR 1910.94 (Ventilation. Std.) <19.5%

29 CFR 1915.11(b) (Shipyards) <19.5%

ANSI Z117.1-1995 (Confined Spaces) <19.5%

ANSI Z88.2-1992 (Respirator Practices) 16.0%2

ACGIH (TLV booklet) 18.0%

1 Letter of interpretation

2 Oxygen partial pressure <122 mmHg. Confined space with <20.9 % O2 is IDLH, unless source of O2 reduction is understood and controlled.

Oxygen-Deficient AtmospheresO2 Content

15-19%

Effects and Symptoms (at patm)

Decreased ability to work strenuously. May impair coordination and induce early symptoms in persons with coronory, pulmonary, or circulatory problems.

Respiration increases in exertion, pulse up, impaired coordination, perception, and judgment.

Respiration further increases in rate and depth, poor judgment, lips blue.

Mental failure, fainting, unconsciousness, ashen face, blueness of lips, nausea, and vomiting.

8 min., 100% fatal; 6 min., 50% fatal; 4-5 min., recovery with treatment.

Coma in 40 sec., convulsions, respiration ceases, death.

12-14%

10-12%

8-10%

6-8%

4-6%

NOTE: Exposure to atmospheres containing 12% or less oxygen will bring about unconsciousness without warning and so quickly that individuals cannot help or protect themselves.

How an Oxygen-Deficient Atmosphere Can Occur in a Confined Space

1. Consumption 3. Adsorption

a) a)

b)

c)

2. Displacement

a)

b)

c)

Argon (Ar)

• Colorless, odorless inert gas• Slightly lighter than air

• Colorless, odorless inert gas• Heavier than air

Nitrogen (N2)

Argon (Ar)

• Colorless, odorless inert gas• Heavier than air

Methane (CH4)

• Natural, marsh, swamp gas• Colorless, odorless flammable gas• Lighter than air• Toxic?• LEL = 5%; UEL = 15%

Carbon Dioxide (CO2)• Colorless, odorless noncombustible gas• Heavier than air• Common in solid and compressed liquid forms• Carbonation• Inerting• Organic decay (grain elevators, sewers, storage bins,

wells)• Fermentation (digestors, molasses pits, beer and wine

vats)

CO2 (cont’d)

• PEL = 5,000 ppm - TWA (Table Z-1)• TLV/REL = 5,000 ppm - TWA; 30,000 ppm - STEL• IDLH = 50,000 ppm• LEL = none

Carbon Monoxide (CO)

• Colorless, odorless gas• Slightly lighter than air• Chemical asphyxiant• Primary source: incomplete combustion of

organic material• Gasoline-fueled combustion engines

CO (cont’d)

• PEL = 50 ppm - TWA• TLV = 25 ppm - TWA• BEI: <3.5% COHb; 20 ppm (end-exhaled air)• REL = 200 ppm - STEL; 35 ppm - TWA• IDLH = 1500 ppm• LEL = 12.5%; UEL = 74.2%

Concentration of CONecessary to Produce Symptoms

Percent ppm Effects

0.02 200 Possibly headache, mild frontal in 2-3 hrs.

0.04 400 Headache, frontal, and nausea after 1-2 hrs.; occipital after 2-1/2 to 3-1/2 hrs.

0.08 800 Headache, dizziness and nausea in 3/4 hour, collapse and possible unconsciousness in 2 hrs.

0.16 1,600 Headache, dizziness and nausea in 20 min.; collapse, unconsciousness, possibly death in 2 hr.

0.32 3,200 Headache and dizziness in 5 to 10 min., unconsciousness and danger of death in 30 min.

0.64 6,400 Headache and dizziness in 1 to2 min., unconsciousness and danger of death in 10 to 15 min.

1.28 12,800 Immediate effect; unconsciousness and danger of death in 1 to 3 min.

(Source: Hamilton & Hardy)

Symptoms of CO Exposure

Percent* Symptoms

0-10 Shortness of breath on exertion

10-20 Tightness across forehead, slight headache

20-30 Throbbing headache

30-40 Severe headache, nausea, vomiting, collapse on exertion

40-50 All symptoms increased, pulse rate and breathing increased

50-70 Coma, interrupted breathing (Cheyne-Stokes), death

* Percent saturation of Hemoglobin with CO [Blood Levels]

Hydrogen Sulfide (H2S)• Sewer gas, stink gas (rotten eggs)• Odor threshold: 0.02 - 0.2 ppm• Colorless, flammable gas• Heavier than air• PEL = 20 ppm - C; 50 ppm - Peak (10 min. once)• TLV = 15 ppm - STEL; 10 ppm - TWA• REL = 10 ppm - C (10 min.)• IDLH = 300 ppm• LEL = 4.3%; UEL = 46%

H2S (cont’d)

• PEL = 20 ppm - C; 50 ppm - Peak (10 min. once)• TLV = 15 ppm - STEL; 10 ppm - TWA• REL = 10 ppm - C (10 min.)• IDLH = 300 ppm• LEL = 4.3%; UEL = 46%

Effects of H2S Concentrationppm* Local Systemic

20

50 Irritant of conjunctival and

corneal epithelium

50-100 Eye and respiratory tract

irritation in 1 hr.

100-150 Slight systemic symptoms after several hrs.

150 Olfactory nerve paralysis Fatal in 8-48 hrs.

200 Pulmonary irritation and pulmonary Nervous system depression

edema after prolonged exposure

* Concentration by Volume

Effects of H2S Concentration (cont’d)

ppm* Local Systemic

250-350 Fatal in 4-8 hrs.

350-450 Fatal in 1-4 hrs.

500-600 Excitement, headache, dizziness and unconsciousness, death in 30-60 min.

600-700 Rapid collapse, death in 2-15 min.

700-2,000 Cessation of respiration, rapidly fatal

* Concentration by Volume

May arise from the:1. Product(s) stored

2. Manufacturing processes

3. Work being performed

4. Adjacent areas

Other Toxics

Definitions• Vapor Pressure- Pressure exerted by a vapor. If a

vapor is kept in confinement over its liquid so that the vapor can accumulate above the liquid, the vapor pressure approaches a fixed limit called the maximum vapor pressure. (How much the liquid wants to become a gas)

• Flash Point- The minimum temperature at which a liquid gives off vapor within a test vessel in sufficient concentration to form an ignitable mixture with air near the surface of the liquid.

Flammable/Combustible Liquid Classification(29 CFR 1910.106)

IIIB (NFPA)

IIIA

II

IC

IB

IA

BOILING POINT

Flammable is <100F0

Combustible is >100F0

100F0

Flammable (Explosive) Limits• When vapors of a flammable or combustible liquid are mixed with air in the

proper proportions in the presence of a source of ignition, rapid combustion or an explosion can occur. The proper proportion is called the flammable range and is also often referred to as the explosive range. The flammable range includes all concentrations of flammable vapor or gas in air, in which a flash will occur or a flame will travel if the mixture is ignited. There is a minimum concentration of vapor or gas in air below which propagation of flame does not occur on contact with a source of ignition. There is also a maximum proportion of vapor in air above which propagation of flame does not occur. These boundary-line mixtures of vapor with air are known as the lower and upper flammable or explosive limits (LFL or UFL) respectively, and they are usually expressed in terms of percentage by volume of vapor in air.

Atmospheric Pressure

• Atmospheric pressure is 760 mmHg a substance with a vapor pressure of 760 mmHg is a gas at room temperature.– Water vapor pressure= 25 mmHg– Fuel oil vapor pressure= 2 mmHg– Vinyl chloride vapor pressure= (760 mmHg)(3.4)

• “1300 rule”– 1300*VP= concentration just above the surface of the

liquid

MSDS Exercise

• What color is this substance?• What type of odor does it have?• What PEL or TLV is set for this substance?• What are some of the synonyms for this substance?• What products are incompatible with this product?• What type of PPE should be worn while handling this product?• What are some of the symptoms of overexposure?• If a co-worker was overexposed to this product what information should be

give to medical personnel?• Is this substance designated as a hazardous waste by the EPA?• Who might you call for more information about this product?

Air Monitoring

Permit-Required Confined Spaces

Objectives

• Describe Why the Work Environment Needs to Be Monitored

• Understand the Value of Personal, Area, and Perimeter Monitoring

• Identify Several Types of Monitoring Equipment

Why Do Monitoring?

• To Detect if Potential Hazardous Conditions

Exist

• To Measure Concentrations of Hazardous

Substances

Detection of Hazards• To Determine Whether Hazardous Materials Are

Present Under Normal Conditions• Whether the Environment is IDLH• Measure Releases During Work to Ensure Proper

PPE and Work Practices• Ensure That No Hazardous Materials Remain

After a Release

Hazards In The Air

• Oxygen Deficiency/Enrichment• Explosive Atmospheres• Toxic Chemicals• Radioactivity• Biological Hazards

Oxygen

Oxygen Deficient

Oxygen Enriched23.5%

19.5%

16.0%

14.0%

6.0%

Minimum for Safe Entry

Impaired Judgment& Breathing

Faulty JudgmentRapid Fatigue

Difficulty in BreathingDeath in Minutes

Explosive Limits

Combustible

UEL

LEL

Too Lean

Too Rich

10% of LEL

Personal Air Monitoring

• Accurate Measure of Actual Exposure

• Compares to OSHA PEL, STEL

• Documents Exposure• Allows Appropriate

PPE Selection

• Lab Analysis 1 to 14 Days

• No Peak or Ceiling Measures

• Need to Know What Exposures are Possible

• Preparation and Calibration Needed Prior and Following

PRO CON

Personal Monitoring Equipment

• Battery Operated Sampling Pumps–Filters - Fumes/Particles/Mists–Charcoal Tubes - Gases/Vapors–Silica Gel Tubes - Gases/Vapors

• Passive Badge DosimetersGases and Vapors

Real-Time Measurements

• Immediate Measures• Measures Variety of

Exposures• Measures IDLH

Situations• Detects Peak Toxic

and Flammable Levels• Determines Ability to

Enter PRCS

• May Not Detect “Low” Levels

• Not Specific• May False Alarm• Interferences and

Cross Sensitivity• May Require Factory

Calibration

PRO CON

Direct Reading Instruments

• Oxygen Meter• Explosive Gas Meter/Combustible Gas Indicator• Detector Tubes• Personal Alarm Monitors• Multi-Gas Analyzer/Meters

Examples of Direct Reading Instruments

Review

• Where Are Measurements Taken?• What Types of Measurements Can Be Made?• How Are These Measurements Used?• What Are Some of the Limitations of Air

Sampling?

Instrumentation

• O2 Meters– Use O2 Meters

• Flammable Gases and Vapors– Use Combustible Gas Indicator

• Toxic Air Contaminants– Use Colorimeteric Detector Tubes

Combustible Gas Indicators

• Used to sample vapor concentrations near and in permit spaces

• Reads LEL

• A reading above 10% should be considered a potentially explosive atmosphere

Combustible Gas IndicatorsPrecautions

• The equipment may not respond the same to all vapors

• O2 MUST BE MEASURED FIRST!

Oxygen Meters• Used to sample oxygen concentrations in and near

confined spaces.• Reads between 0-25% or 0-100%• At greater than 23.5% O2, the explosion hazard

increases.• At less than 19.5% the space cannot be entered

without a SCBA or SAR with escape pack.

Oxygen Meter Precautions

• Very sensitive to temperature and pressure changes.

• At high concentrations of carbon monoxide, the meter may give improper readings.

• Must be calibrated before every use!

Colorimeteric Detector Tubes

• Used to sample gas or vapor concentration in any work space.

• Reads percent of the concentration in PPM.

• Concentration indicated by color change or length of color stain.

Detector Tube Precautions

• They are not very accurate-- within 25% of the real value at best.

• The tubes are very sensitive to temperature and humidity.

• Different tubes must be used for different chemicals.

• They are breakable.

Tips To Help In Monitoring

• Check the accuracy of the instruments you are going to use.– Have they been recently calibrated?

• Always test in this order: Oxygen, Flammability/Combustibility, and Toxic Gases.

• Test the air from the top to bottom including all corners and spaces!

• Test the atmosphere frequently!

Ventilation of Permit-RequiredConfined Spaces

Comfort - General/Dilution Ventilation

• Temperature and humidity regulationsASHRAE 55-1992– Winter: 68 - 74oF– Summer: 73 - 79oF– RH: 30 - 60 %

Comfort - General/Dilution Ventilation (cont’d)

• Odor removal - outside air movementASHRAE 62 - 1989– Public bathrooms: 50 CFM/wc or 2 CFM/ft2

– Office: 15 CFM/person– Smoking lounges: 20 - 60 CFM/person

Safety - General/Dilution Ventilation

Fire and explosion control

LELVV = cubic feet of vapor per gallon of solvent (vapor volume)

Dilution volume =4(100-LEL)VV

(1) Volume of air required to dilute the vapor from 1 gallon of solvent to 25% LEL. [1910.94(c)(6)(ii)]

Safety - General/Dilution Ventilation (cont’d)

Example: acetone

2.5

= 6,864 ft3 air / gal acetone (70oF)

Dilution volume =4(100-2.5)44.0


LELDilution volume =

10(100 - LEL)VV

(2) Volume of air required to dilute the vapor from 1 gallon of solvent to 10% LEL. [1910.146(b)]


Example: acetone

2.5Dilution volume =

10(100 - 2.5)44.0

= 17,160 ft3 air / gal acetone (70oF)

Ventilation Volume Calculation

Ventilation volume = Dilution volume x Gallons of solvent evaporated per minute

CFM = ft3 air

gal solvent

gal solvent

minx

Ventilation Volume Calculation (cont’d)

Example: Acetone-thinned paint applied at rate of one gallon per minute. Paint is 40% solvent.

Ventilation volume (for 25% LEL)

6,864 ft3 air 1 gal paint 0.4 gal solvent

gal solvent min gal paint

x x = 2,746 CFM

Ventilation volume (for 10% LEL)

17,160 ft3 air 1 gal paint 0.4 gal solvent

gal solvent min gal paint

x x = 6,864 CFM

Dilution Ventilationfor Fire and Explosion

• Reduce the concentration of vapors within an enclosure to below the LEL.

• This concept is never applied in cases where workers are exposed to the vapor. Dilution rates for health hazard control are always applied in these instances, since the PEL is a much lower concentration than the LEL.

Safety - Dilution Ventilation

403(SG)(100)(C)(w)

(MW)(LEL)(B)Q =

where,

Q = air flow rate (CFM) required to dilute vapor concentration to safe condition

403 = conversion factor

SG = specific gravity of liquid (water = 1)

Safety - Dilution Ventilation (cont’d)

100 = constant to convert LEL to decimal fraction

C = dimensionless safety factor which depends on % LEL necessary for safe conditions (10% LEL: C = 10, 25% LEL: C = 4)

w = pints of liquid evaporated in one minute

MW = molecular weight of vapor

LEL = lower explosive limit (%)

B = constant reflecting fact that LEL decreases at elevated temperatures (£ 250oF: B = 1, > 250oF: B = 0.7)

Flammable Liquid Storage Rooms

Ventilation must provide for a complete change of air within the room at least six times per hour (6 A.C. / hr).

Exchanging all the air in the room is equivalent to 1 A.C. [i.e., Room volume (L x W x H) = 1 A.C.]

6 A.C. / hr = (6 x Room volume) / hr

CFM = [6 x Room volume (ft3)] x 1 hr / 60 min

CFM = Room volume (ft3) / 10

Health - Dilution Ventilation

403(SG)(106)(w)(K)

(MW)(PEL)Q =

where,

Q = air flow rate (CFM) required to dilute vapor concentration to the PEL.

K = dimensionless safety factor (varies from 3-10) to maintain concentration well below PEL. Higher value for high toxicity, high evolution rate, poor ventilation, and large number of exposed workers.

Considerations for PRCS Ventilation

• Space configuration• Ventilation mode (exhaust/supply)• Ventilation flow rate• Availability of make-up air• Obstacles for ducting• Availability of power sources• Location of employee within space• Characteristics of contaminant

Achievement of Accceptable Atmospheres

• Dilution - use general/forced air ventilation to dilute the contaminant

• Exhaust - use local exhaust ventilation to remove the contaminant

• Dilution/Exhaust - use a combination of both methods to remove the contaminant

Dilution Ventilation

• Introduces fresh air to space• Best when toxicity levels

and concentrations are low• Best when contaminants

well distributed• Requires larger air volume

when contaminants generatedat a point

Local (Source) Ventilation

• Exhausts from a localized area• Removes high concentrations

of contaminants from space• Requires smaller volume

of air

Solutions

• Inerting• Purging• Ventilation

Inerting

• Displacement of the atmosphere by a non-reactive gas (such as nitrogen) to such an extent that the resulting atmosphere is noncumbustible.

Purging• The method by which gases, vapors, or other airborne

impurities are displaced from a confined space.• Purpose is to do a complete air exchange in a confined space

prior to entry. Normally, a purge is considered complete when atmospheric tests indicate the air is of suitable quality to sustain life.

Inerting• Displacement of the atmosphere by a non-reactive gas

(such as nitrogen) to such an extent that the resulting

atmosphere is noncumbustible.

Ventilation

• At opening of blower 100% capacity

• Blower plus 25’ of hose 78% capacity

• 25’ of hose plus one 90 degree bend 67% capacity

• 25’ of hose plus two 90 degree bend 56% capacity

Electricity

• Electricity Doesn’t Spring Into Action Until Current Flows

• Current Doesn’t Flow Until there is a Loop to and from the Transformer

• Current Always Returns to the Transformer that created it

Electricity

• Voltage Water Pressure• Ohms Resistance / Size of Water Pipe• Current Flow Rate of Water

Electrical Shock

• Contact with a normally energized conductor (wire).

• Contact with an energized conductor on which the insulation has lost it’s protective value

• Equipment failure, causing an open or short circuit• Static Electricity Discharge• Lightning Strike

Cords & Corded Equipment• Do not remove ground plug• Flexible cords must Not be:

Used instead of fixed wiringRun through holes in ceilings, walls, or floorsRun through doorways, windows, or openingsConcealed in walls, ceilings, or floors

• Flexible cords may be used for:PendantsFixture wiringPortable lamps or appliancesCranes and hoistsFrequently Moved equipment

Lockout/Tagout

29 CFR 1910.147Control of Hazardous Energy Sources

(Lockout/Tagout)

Scope 1910.147 (a)(1)(i)

• Covers servicing and maintenance of machines when unexpected startup or release of stored energy could cause injury.

Application 1910.147 (a)(2)(i)

• Standard applies to control of energy during servicing and/or maintenance.

• Note: Servicing / maintenance during normal production operations is covered if:

an employee is required to remove or bypass a guard, or

an employee must place his / her body into danger zone

Does not cover: 1910.147 (a)(1)(ii)

• Construction, agriculture, maritime• Installations under control of electric utilities• Exposure to electrical hazards from work on,

near, or with conductors or equipment in electrical utilization installations (see Subpart S)

• Oil and gas drilling, and servicing

Also Excluded 1910.147 (a)(2)(ii) & (iii)

• Normal production operations (see Subpart O)• Work on cord and plug connected equipment• Hot tap operations, under special conditions

Definitions 1910.147 (b) & (c)(7)(i)(C)

*While not defined in 1910.147 (b), “other employees” are discussed in 1910.147 (c)(7)(i)(C).• Authorized Employee: Person who locks or tags machines / equipment to perform servicing.

• Affected Employee: One who is required to use machines / equipment on which servicing is performed under lockout / tagout or who must work in such an area.

• Other Employees: * All employees whose work operations are or may be in an area where energy control procedures may be utilized.

Definitions (continued) 1910.147 (b)

“Capable of being locked out”• Designed with hasp or attachment to which lock

can be affixed; or,• Has locking mechanism built in; or, • Lockout can be achieved without need to

dismantle, rebuild, replace or permanently alter.

Definitions (continued)1910.147 (b)

• Normal Production Operations: Utilization of a machine or equipment to perform its intended function.

• Servicing and/or Maintenance: Includes lubrication, cleaning or unjamming, making adjustments and tool changes, where employees may be exposed to UNEXPECTED energization, startup or release of hazardous energy.

Energy Control Program1910.147 (c)(1)

• The employer shall establish a program consisting of an energy control procedure and employee training... in accordance with paragraph (c)(4) of this section.

Lockout vs. Tagout

• Lockout system is preferred method and shall be used when equipment can be locked out -- unless employer can show that tagout system provides full employee protection.

Full Employee Protection1910.147 (c)(3)(i)

• When tagout is used on equipment which is capable of being locked out:

Tags shall be attached where lockout devices would be; and,

Employer must demonstrate that tagout will provide safety equivalent to lockout.

Energy Control Procedure1910.147 (c)(4)(i)

• Procedures shall be developed, documented and utilized for the control of potentially hazardous energy when employees are engaged in servicing and maintenance.

Energy Control Procedures must be written, unless all of the following exist: 1910.147 (c)(4)(i) -

exception• Equipment has no potential for stored / residual energy.• Equipment has a single energy source.• Isolation and lockout of one energy source completely

deactivates equipment.• Equipment is isolated from energy source & locked out.• Lockout device is under exclusive control of authorized

employee performing maintenance.• No other hazards are created.• Employer has had no related accidents.

Procedures must contain: 1910.147 (c)(4)(ii)• Scope

• Purpose• Authorization• Rules• Techniques to be utilized• Means to enforce compliance

Materials / Hardware1910.147 (c)(5)

• Provided by employer• Singularly identified• Only devices used• Not used for other purposes• Durable• Standardized• Substantial

Periodic Inspection 1910.147 (c)(6)(i)• At least annually

• Performed by authorized employee (other than the one(s) using procedure being inspected).

• Designed to correct deficiencies.• Lockout: Must review each authorized employee’s

responsibilities.• Tagout: Must review each authorized and affected employee’s

responsibilities and additional training requirements of 1910.147 (c)(7)(ii).

• Employer certification required.

Training1910.147 (c)(7)(i)

• Authorized Employee– Recognition of hazardous energy sources– Type & magnitude of energy in workplace– Methods for energy isolation / control

• Affected Employee– Purpose / use of energy control procedure

• Other Employee– Procedure– Prohibition on restarting machines or equipment

Additional Training - Tagout System 1910.147 (c)(7)(ii)

• Employees shall be trained in the limitations of tags, as follows:– Warning devices only– Must not be removed / bypassed / ignored– Must be legible– Must withstand environmental conditions– May (will) evoke false sense of security– Must be securely attached

Employee Retraining 1910.147 (c)(7)(iii)

• Provided when:–Change in job assignments–Change in machines, equipment or processes

that present new hazards–Change in energy control procedures–Periodic inspection reveals, or employer has

reason to believe, there are deviations in employee knowledge of procedures

Specific Procedures 1910.147 (d)(1) - (6)

• Lockout / Tagout procedures shall cover the following elements in the following sequence:–Preparation for shutdown–Shutdown – Isolation–Lockout / tagout device application–Release of stored energy–Verification of isolation

Release from Lockout / Tagout 1910.147 (e)(1) - (3)

• Prior to restoring energy, the following procedures are required:–Inspect machine and equipment–Safe positioning and notification of

employees–Removal of lockout / tagout device

Testing of Machines 1910.147 (f)(1)

• When lockout / tagout devices must temporarily be removed for testing / positioning:–Clear machine of tools / equipment–Remove employees–Remove lockout / tagout device–Energize and test–De-energize and reapply energy control measures

Outside Personnel (Contractors) 1910.147(f)(2)

• On-site employer and outside employer shall inform each other of their respective procedures.

• On-site employer shall ensure that his / her employees understand and comply with contractor’s procedures.

Group Lockout / Tagout1910.147 (f)(3)

• Additional Requirements–Primary responsibility is vested in an authorized

employee for a set number of employees.–Authorized employee must ascertain exposure status of

group members.– If more than one crew is involved, coordinator needed.–Each authorized employee shall use a personal

lockout / tagout device and remove it when finished.

Shift / Personnel Changes 1910.147 (f)(4)

• Specific procedures needed to ensure continuity of lockout / tagout protection.

Lockout/TagoutPurpose - 1910.147(a)(3)

This section requires employers to establish a program andutilize procedures for affixing appropriate lockout devices ortagout devices to energy isolating devices, and to otherwisedisable machines or equipment to prevent unexpected energization, start-up or release of stored energy in order toprevent injury to employees.

Lockout/TagoutDefinitions - 1910.147(b)

Affected employee: An employee whose job requires him/her to operate or use a machine or equipment on which servicing or maintenance is being performed under lockout or tagout, or whose job requires him/her to work in an area in which such servicing or maintenance is being performed.

Authorized employee: A person who locks out or tags out machines or equipment in order to perform servicing or maintenance on that machine or equipment. An affected employee becomes an authorized employee when that employee’s duties include performing servicing or maintenance covered under this section.

Energy isolating device: A mechanical device that physically prevents

the transmission or release of energy.

Lockout/TagoutEmployer Responsibilities

Education– Documentation: a written statement of company’s Energy

Control Plan.– Employee training: to help employees in the use of the Energy

Control Plan.

Enforcement– Inspection: to make sure energy control procedures are being

carried out.– Self-audit: a periodic review of the procedures and the

program.

Lockout/TagoutGeneral - 1910.147(c)

The employer shall establish a program consisting of energycontrol procedures, employee training and periodic inspectionsto ensure that before any employee performs any servicing ormaintenance on a machine or equipment where the unexpectedenergizing, start up or release of stored energy could occur andcause injury, the machine or equipment shall be isolated fromthe energy source, and rendered inoperative.

Lockout/TagoutApplying Energy Controls

• Energy isolation and lockout/tagout are to be applied only by trained employees authorized to perform service or maintenance.

• Before lockout/tagout is applied, all employees who work in the affected area must be notified.

• The OSHA regulation requires that control of hazardous energy be done according to a six-step procedure.

Lockout/TagoutPreparation for Shutdown - 1910.147(d)(1)

• The types and amounts of energy that power it• The hazards of that energy• How the energy can be controlled

Before you turn off any equipment in orderto lock or tag it out, you must know:

Lockout/TagoutEquipment Shutdown - 1910.147(d)(2)

• Shut the system down by using its operating controls.

• Follow whatever procedure is right for the equipment, so that you don’t endanger anyone during shutdown.

• An orderly shutdown must be utilized to avoid any additional or increased hazard(s) to employees as a result of the equipment stoppage.

Lockout/TagoutEquipment Isolation - 1910.147(d)(3)

• Operate all energy-isolating devices so that the equipment is isolated from its energy sources.

• Be sure to isolate all energy sources-secondary power supplies as well as the main one.

• Never pull an electrical switch while it is under load.

• Never remove a fuse instead of disconnecting.

Lockout/TagoutApplication of LOTO Devices - 1910.147(d)(4)

• All energy-isolating devices are to be locked, tagged or both according to company’s Energy Control Plan.

• Only the standardized devices supplied by your employer are to be used for lockout/tagout, and they are not to be used for anything else.

• Use a lockout device if you lock cannot be placed directly on the energy control.• When lockout is used, every employee in the work crew must attack his/her personal lock.• More than one employee can lock out a single energy-isolating device by using a

multiple-lock hasp.• For big jobs, a lockout box can be used to maintain control over a large number of keys.• If tags are used instead of locks, attack them at the same point as you would a lock, or as

closed to it as possible.• Fill tags out completely and correctly.

Lockout/TagoutControl of Stored Energy - 1910.147(d)(5)

• Inspect the system to make sure all parts have stopped moving.• Install ground wires.• Relieve trapped pressure.• Release the tension on springs, or block the movement of

spring-driven parts.• Block or brace parts that could fall because of gravity.• Block parts in hydraulic and pneumatic systems that could

move from loss of pressure.

Lockout/TagoutControl of Stored Energy (con’t.)

- 1910.147(d)(5)• Bleed the lines and leave vent valves open.• Drain process piping systems and close valves to prevent the

flow of hazardous materials.• If a line must be blocked where there is no valve, use a blank

flange.• Purge reactor tanks and process lines.• Dissipate extreme cold or heat, or wear protective clothing.• If stored energy can reaccumulate, monitor it to make sure it

stays below hazardous levels.

Lockout/TagoutEquipment-Isolation Verification - 1910.147(d)(6)

• Make sure all danger areas are clear of personnel.• Verify that the main disconnect switch or circuit breaker can’t be

moved to the on position.• Use a voltmeter or other equipment to check the switch.• Press all start buttons and other activating controls on the equipment

itself.• Shut off all machine controls when the testing is finished.

Take any of the following steps that fit your company’s equipment and energy control program.

Lockout/TagoutRemoving Energy Controls

• Make sure the equipment is safe to operate.– Remove all tools from the work area.– Be sure the system is fully assembled.

• Safeguard all employees.– Conduct a head count to make sure everyone is clear of the equipment.– Notify everyone who works in the area that lockout/tagout is being

removed.

• Remove the lockout/tagout devices. Except in emergencies, each device must be removed by the person who put it on.

Lockout/TagoutRemoving Energy Controls (con’t.)

• In some workplaces, the last person to remove his/her lock may have extra duties.–He/she may have to remove the hasp and

lockout device.–Tags should be removed, signed, and turned in.– In some companies, the supervisor always

removes his lock last.• Follow a checklist of required steps to re-energize

the system.

Limitations of Tags1910.147(c)(7)(ii)

• Tags are essentially warning devices affixed to energy isolating devices, and do not provide the physical restraint on those devices that is provided by a lock.

• When a tag is attached to an energy isolation means, it is not to be removed without authorization of the authorized person responsible for it, and it is never to be bypassed, ignored, or otherwise defeated.

• Tags must be legible and understandable by all authorized employees, affected employees, and all other employees whose work operations are or may be in the area, in order to be effective.

• Tags and their means of attachment must be made of materials which will withstand the environmental conditions encountered in the workplace.

• Tags may evoke a false sense of security, and their meaning needs to be understood as part of the overall energy control program.

• Tags must be securely attached to energy isolating devices so that they cannot be inadvertently or accidentally detached during use.

Respiratory Protection• The basic function of a respirator is to reduce the risk of respiratory injury due

to breathing airborne contaminants. A respirator provides protection by removing the contaminants from ambient air or by supplying the wearer with an alternate source of clean breathing air.

• All respiratory apparatus are composed of two main parts:– the device which supplies or purifies air,– the facepiece which covers the nose and mouth and seals out the

contaminants. – The first component defines what class of respirator the device is; the

second determines the relative measure of protection afforded by that respirator.

1. Selection

2. Medical evaluation

3. Fit testing

4. Use

5. Maintenance and care

6. Breathing air quality and use

7. Training

8. Program evaluation

Respirator Program Elements

Respiratory Protection

Classifications of respirators:–Air purifying respirators (APRs)

• Particulate- mechanical filter• Gas and vapor- chemical cartridge• Requires knowledge of ambient concentration and

Maximum Use Limit (MUL) of the respirator• APRs only clean the air, the ambient concentration of

oxygen must be sufficient (19.5%) for the user

Air-Purifying Respirator (APR)

• An air-purifying respirator that uses a blower to force the ambient air through air-purifying elements to the inlet covering.

Respiratory Protection

Classifications of respirators:• Air supplying respirators (ASRs)

– Provide a substitute source of clean breathing air.– The respirable air is supplied to the worker from either

a stationary source through a long hose, or from a portable container.• The first type are called supplied-air respirators.

• The second type are known as self-contained breathing apparatus.

Supplied Air Respirator (SAR)• An atmosphere-supplying respirator for which the source

of breathing air is not designed to be carried by the user. Also called airline respirator.

Self-Contained Breathing Apparatus (SCBA)

• An atmosphere-supplying respirator for which the breathing air source is designed to be carried by the user.

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permit-required confined space entry 29 cfr 1910.146

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