psat user manual

OFFICE OF INDUSTRIALTECHNOLOGIES

OFFICE OF INDUSTRIAL TECHNOLOGIESENERGY EFFICIENCY AND RENEWABLE ENERGY • U.S. DEPARTMENT OF ENERGY

FOR ADDITIONAL INFORMATION, PLEASE CONTACT:

The OIT ClearinghousePhone: (800) 862-2086Fax: (360) 586-8303

Please send any comments,questions, or suggestions [email protected]

Visit our home page atwww.oit.doe.gov.

Office of Industrial TechnologiesEnergy Efficiencyand Renewable EnergyU.S. Department of EnergyWashington, DC 20585

February 2000

Pumping SystemAssessment ToolUser Manual

Prepared by the Oak Ridge National Laboratory, managed by Lockheed Martin Energy ResearchCorporation for the U.S. Department of Energy under contract number DE-AC05-96OR22464.

The submitted manuscript has been authored by a contractor of the U.S. Government under con-tract DE-AC05-96OR22464. Accordingly, the U.S. Government retains a non-exclusive, royalty-freelicense to publish or reproduce the published form of this contribution, or allow others to do so,

for U.S. Government purposes.

Contents

Page

INTRODUCTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

SYSTEM REQUIREMENTS AND SETTINGS . . . . . . . . . . . . . . . . . . . . . . . . 1

PSAT INSTALLATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

DESCRIPTION OF FRONT PANEL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

Pull-Down Menus. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2Main Screen Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3Pump, Motor, System Information. . . . . . . . . . . . . . . . . . . . . . . . . . . 4Operating Parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6Measured or Required Conditions. . . . . . . . . . . . . . . . . . . . . . . . . . . 6Calculated Results. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8Log File Controls. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10Summary File Controls . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11General Identification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12STOP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12Background Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

INFORMATION/TOOLS ACCESSED BY "CLICK FOR BACKGROUND INFORMATION" BUTTON . . . . . . . . . . . . . . . . . . . . . . . . 13

Section Menu List . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13General Background . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13System Measured Conditions vs. Actual Requirements . . . . . . . . . . . 15Sources of System Losses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15Pump Efficiency Factors. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16Achievable Efficiency. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17Achievable Efficiency Penalty vs. Specific Speed . . . . . . . . . . . . . . . 18Specific Speed Discussion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18Typical Pump Curves . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19Motor Efficiency Factors. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20Motor Performance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

REFERENCES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

Pumping System Assessment Tool User Manual 1

INTRODUCTION

The Pumping System Assessment Tool (PSAT) is a software program developed by theDepartment of Energy’s (DOE) Office of Industrial Technologies (OIT) to assist engineers and facility operators in performing assessments of pumping system energy usage. PSAT is also wellsuited for performing plant energy usage surveys by consultants or plant engineers. End users inthe field will find PSAT easy to use due to the fact that it was carefully designed to require only theminimum essential operation data (or requirements) to perform its analysis.

For many industrial facilities, the energy consumed in pumping fluids comprises a large fraction of the total energy consumption of the facility. Operators are often not aware of howeffectively energy is being consumed in pumping systems. The PSAT tool provides a relatively simple and fast means of determining system efficiency and potential alternatives. Using generictypical performance characteristics of pumps and motors, estimates of potential savings in termsof energy and dollars are provided.

Although PSAT does not tell how to improve systems, it does prioritize options for efficiencyimprovement and allows the user to broaden or narrow searches for improving efficiency.

This manual describes PSAT2000 (version 1.2), which will be referred to as simply PSATthroughout the remainder of this document. Although much care was taken in testing this software,it is still an early version and it is possible that some users may experience problems using certainhardware/software combinations and configurations. Information regarding sources of technicalhelp are provided in PSAT and in this manual.

SYSTEM REQUIREMENTS AND SETTINGS

The system requirements for operating PSAT are as follows:

—Microsoft Windows NT or Windows 95/98. PSAT is not compatible with earlier versions of Windows.

—Display resolution of at least 800 x 600 pixels.

—A hard drive with at least 5 megabytes of available space.

—Although PSAT will run with 16 megabytes of RAM, at least 32 megabytes is recommended.

PSAT INSTALLATION

If you are installing PSAT from a CD or diskettes, follow the instructions accompanying the disk.

To obtain PSAT from the World Wide Web, follow these steps:

1. Using the “open page” feature on your internet browser (or using the location or URL box at the top of the page) enter the address:

http://public.ornl.gov/psat

2 Pumping System Assessment Tool User Manual

2. Complete the registration form and then click the Download button.

3. After downloading the setup file, double-click on it to start installation.

DESCRIPTION OF FRONT PANEL

The main PSAT screen (i.e., front panel) is shown in Figure 1. When PSAT is started, it appearson the screen in an active (i.e., operating) mode as indicated by the black arrow ( ) under theEdit menu in the upper left-hand corner, and with a STOP button in the lower right-hand corner.Since PSAT continues to operate in a loop mode, other Windows applications may operate moreslowly. Therefore, unless the user actually needs updated results from PSAT, it may be helpful toclick STOP. After clicking the STOP button, the black arrow will turn white ( ). PSAT can berestarted by clicking on the white arrow button. To exit the PSAT application, click STOP beforeclosing the window using the standard close box in the upper-right hand corner.

Pull-Down MenusThis section describes the most useful pull-down menus for PSAT: the Help, Print, and Preferences

menus.A help box can be enabled/disabled by use of the pull-down “Help” menu at the top of the screen

by selecting/unselecting the “Show Help” item. When “Show Help” is enabled, a box appears that

Figure 1. Main screen of PSAT.

3Pumping System Assessment Tool User Manual

contains descriptive text about the front panel element that the mouse pointer/cursor is on or near.This important feature can be used as needed during the learning process. The “Show Help” can alsobe toggled on and off using the keyboard sequence Ctrl-H.

The About selection under the “Help” menu provides information about the source of PSAT andhow to obtain assistance in its use.

To print pages from PSAT, go to whatever screen in PSAT you wish to print and, using the pull-down menu under “File” and “Printer Setup,” select a portrait page orientation or, if a large image isdesired, a landscape orientation. Next, under “File” and “Print Window,” select “Ok” to begin printing.

Printing options can be changed by selecting “Preferences” under the Edit menu. After selectingPreferences, go to the arrow in the top box and choose “Printing.” Standard Printing is the defaultselection; users with PostScript printers may get better performance if the PostScript option is selected.The default print option is black and white printing. For those with color printers who wish to capturecolors, such as the “Optimization rating” background color, the “Color/Grayscale printing” featurecan be checked.

PSAT is a type of LabVIEWTM based software package that is generically referred to as a virtualinstrument (vi). The PSAT version number can be seen by using the “Windows” pull-down menu andselecting “Show VI Info.”

Main Screen Features

The main headings of the front panel are as follows:

1. Pump, motor, system information—This section requires easily supplied fundamental data, mostly regarding the process fluid and data from the pump and motor nameplates.

2. Operating parameters—Requires information on pump system duty cycle and electricity costs.

3. Measured or required conditions—Requires user to supply either measured electrical/fluid dataor system requirements.

4. Calculated results—The PSAT output is provided in this section in tabular form. The results of several derivations are summarized for differing levels of optimized pump hardware.

5. Log file controls—In this box, the user can process (i.e., create, retrieve, delete) logs of screen data.

6. Summary file controls—These controls allow the user to create and append to summary data files that are tables containing data from the main screen. These can be read with data base or spreadsheet software.

7. General Identification Data—The bottom set of boxes (Facility, System, Date, Application, Evaluator, and Notes) contain general documentation items provided by the user.

8. STOP control button, which is used to interrupt the calculations being done by PSAT.

9. Background information access—A button control which enables access to background and support information.

Figure 1 shows a case where pump motor power measurements (i.e., “measured power”) aresupplied by the user in the box under “Measured or required conditions.” The same screen isshown in Figure 2 except, in this case, the user supplies pump motor current instead of power.

Pumping System Assessment Tool User Manual4

Note that specifying current instead of power causes an additional input, motor nameplate full loadamps, to appear at the bottom of the box labeled, “Pump, motor, system information.

Using text similar to that provided in the help box, details of each input, switch, and outputfield of the front panel are described below, with a corresponding graphic indicating the applicablearea of the PSAT display.

Pump styleThe pump style list is based on a listing of styles in Hydraulics Institute (HI) standard ANSI/HI

1.3-1994 [1], Centrifugal Pump Design and Application (and also in a paper published by HI,Efficiency Prediction Method for Centrifugal Pumps) [2].

Figure 2. Main screen of PSAT with required current selected.

Pump, Motor, System Information

(Power as Load Estimation Method) (Current as Load Estimation Method)


The HI standard provides graphical data showing generally attainable efficiencies by pumpstyle as a function of capacity. There is also a graph showing the typical effects of pump specificspeed on efficiency. The PSAT software uses curve fits of the HI standard graphical data to developthe "Optimal pump" efficiency for the specified flow rate, head, and rotating speed conditions.

Fixed pump configurationThe fixed pump configuration switch (located far left on the screen) allows the user to constrain

the pump speed and number of stages to the existing design (i.e., “Yes” selection) or, using the“No” selection, allows the PSAT software to select a pump whose specific speed is optimal for thespecified flow rate and head values.

Fluid viscosityThe fluid kinematic viscosity (in centistokes) is used in determining achievable pump efficiency,

using methods defined in ANSI/HI 1.3 [1]. The default value of 1.0 applies to water at 68°F.

Pump nameplate speed, rpmThe nameplate speed for the pump is used, along with the measured/required flow rate and

head and number of stages, to calculate the pump specific speed. The specific speed is used todetermine efficiency penalty associated with the particular pump application.

Specific gravityThe fluid specific gravity is the ratio of the density of the fluid to water at standard conditions.

It is used in calculating the fluid horsepower at the specified pump flow rate and head conditions.

Number of stagesThe number of pump stages is used to calculate pump specific speed.

Nameplate hpThe existing motor hp is the nameplate rating for the existing motor

Motor nameplate speed, rpmThe motor nameplate speed is used to determine the number of motor poles, which in turn is

used, along with the motor class and size, to estimate motor efficiency and output shaft power forthe measured electrical power or current conditions. The estimation is based on average performanceof motors in the specified class from the MotorMaster+ database [3].

Existing motor classThere are three classes of motors available in this menu list item: Energy efficient, Standard

efficiency, and Average.

The motor classification is based on how the motor rated efficiency compares with the NationalElectrical Manufacturers Association (NEMA) MG 1-1993, Table 12-10 standard [4]. If at or above theTable 12-10 Nominal Efficiency, the Energy efficient classification applies; if below, the Standard efficiency classification should be used. The classification is used in estimating the motor efficiencyand output power conditions; if current is the specified load estimation method, it is also used to estimate input power. The Average class can be used if the user is uncertain which class shouldapply; it is the average of the energy efficient and standard efficiency classes.

Nominal motor voltage, voltsThe nominal motor voltage is the motor design (nameplate) voltage. The Pumping System

Assessment Tool develops load and efficiency estimates based on normalized characteristics for 460-volt rating from the MotorMaster+ database. That is, the profiles of current, efficiency, and inputpower as a function of rated load conditions are normalized to their respective values at rated load.


Since the normalized performance of motors is minimally affected by rated voltage, the 460-voltcharacteristic motor performance curve shapes are used for all nominal voltages. Efficiency as a percent of load is held constant; average current is adjusted inversely to the ratio of voltage.

Initialize full load amps to typical valueThis button can be used to estimate full load amps once the motor size, speed, class, and nominal

voltage have been specified. If full load current is available from the motor nameplate, it should beused in lieu of the typical value.

Motor nameplate full load amps at rated voltageThe full load amps from the motor nameplate should be specified here. If not available, this can

be estimated (once the motor size, speed, class, and nominal voltage have been selected) using theInitialize full load amps button.

Operating fractionThis is simply the fraction of the calendar hours that the equipment is operating at the specified

conditions. It is used in calculating the annual cost results. A value of 1.000 (default) suggests thepump is operated continuously.

Electricity cost, cents/kwhrThis is, as the name suggests, the per unit energy cost of electricity.

Measured/Required flow rate (gpm)Either the measured or the required flow rate in U.S. gallons per minute is specified here. The value

entered here is used by the software to calculate the fluid horsepower (which is used to estimate existing pump efficiency) and to estimate the optimal pump operating efficiency.

Measured/Required head (ft)Either the measured or the required head, in feet, is specified here. The value entered here is

used by the software to calculate the fluid horsepower, which is in turn used to estimate existingpump efficiency.

Load estimation methodThere are two choices of load estimation methods: Power and Current, where Power refers to

electrical power input to the motor.

The preferred load estimation method is power. If input power is accurately measured, the estimate of both pump and motor efficiencies will likely be more accurate than if current alone ismeasured.

Operating Parameters

Measured or Required Conditions


If a power measurement is not practical, current can be used to estimate input power. The power estimate from current is made based on a curve fit of the average MotorMaster+ database current vs. load profile for the specified motor size, class, and speed.

Measured power (kwe)—Note: This parameter only appears when power is the specified load estimation method. Measured motor input power is the preferred Load estimation method. If possible, the measured power should be the combined, three-phase power, rather than a projection of a single phase measurement.

Measured current (amps)—Note: This parameter only appears when current is the specified loadestimation method. Measured current is the less desirable method PSAT can use to estimate motorinput power. This method uses the motor performance characteristics developed from theMotorMaster+ database to estimate power from measured current.

If an electrical type of adjustable speed drive (such as a variable frequency drive) is used, current should not be used as the load estimation method, since the current vs. load profile is significantly affected by the drive. As an alternative, an estimate of input power can be madeusing measured current (from the line to the variable frequency drive) and power factor data provided by the drive manufacturer. If a power factor correcting capacitor bank is used for theindividual motor load, it is important that the current be measured downstream of the paralleledcapacitor bank (i.e., on the motor side of the bank, not the line side). Finally, if possible, the valueentered should be the average current among the three phases.

Measured bus voltage The measured bus voltage is used, along with the measured current, to estimate motor input

power, if motor current is the selected Load estimation method. Alternatively, if motor power is theselected Load estimation method, the voltage is used to estimate current. The estimate of powerfactor is also affected by the measured voltage.

A simple algorithm based on a combination of sources is used to adjust for over/under volt-age. The algorithm assumes that at 100% of rated load, current drops 1% for every 1% increase in voltage (or vice-versa at reduced voltage). At the other end of the load scale—no load, the algorithm assumes that current increases 1% for every 1% increase in voltage (and vice-versa atreduced voltage). The relationship is assumed linear with load, so that at 50% load, current isassumed to be unaffected by voltage.

It is recognized that such a simplistic algorithm cannot accurately capture response of allmotors. Nevertheless, it is believed to be reasonably representative, and has been used with goodsuccess on a number of motors in actual field service.

Input basisThe input basis selector switch does nothing but change the labels for the flow rate and head

input parameters. It does this to serve as a reminder of the absolute criticality of distinguishingbetween what is measured and what is really required. In many cases, the greatest opportunity forsavings in pumping systems is in making this distinction and then taking actions to bring the twocloser together. A discussion of this can be accessed in the PSAT by clicking the Click for backgroundand other information button.

The first column of the Calculated Results section (labeled Existing pump, motor) reports the estimates of existing pump and motor performance characteristics, including efficiency, energyconsumption, and cost. The potentially achievable results if the existing motor was replaced withan energy efficient motor are shown in the second column (labeled Existing pump, EE motor). If the existing motor selection is energy efficient, as in the above display, the first and secondcolumns are identical. Finally, the potentially achievable results if both an energy efficient and anoptimal pump are employed are shown in the third column (labeled Optimal pump, EE motor).


Calculated Results

The efficiency, and other performance characteristics, of an energy efficient motor are basedon the MotorMaster+ database [3]. The optimal pump efficiency is based on the HI standard [1].

Pump efficiencyPump efficiency is equal to the fluid power provided by the pump divided by the pump’s shaft

input power.

Fluid power is calculated from the specified flow rate, head, and specific gravity, and is definedas:

Q x H x s.g.Pfl =

3960

where Pfl is the fluid power (hp), Q is the flow rate (gpm); H is the head (ft), and s.g. is the specific gravity.

The shaft power for the Existing pump and motor is estimated based on the specified or estimated motor input power, and on the performance characteristics for the designated motorsize, speed, and efficiency class. The same type of estimate is performed for the Existing pump andEE motor, except that efficiency for an energy efficient motor is assumed.

Pump efficiency for the Optimal pump and EE motor is estimated based on the specified flowrate, head, pump speed, number of stages, and fluid viscosity. ANSI/HI 1.3-1994, Centrifugal PumpDesign and Application [1] is used in making this estimate; the value calculated is the optimally achievable value.

If the fixed pump configuration? switch is set to “Yes”, the pump speed and number of stages willbe constrained to the specified values, and a penalty for pump specific speed may apply. If it is setto “No”, the optimal value will not include the pump specific speed penalty—i.e., the software willdetermine the optimum achievable efficiency without consideration of the number of stages orspeed for the specified flow rate. It should be noted that the Pump style affects achievable pumpefficiency, regardless of the Fixed pump configuration switch setting.


Motor rated hpThe motor rated hp for both the Existing pump, motor and Existing pump, EE motor columns is

the motor hp specified in the Nameplate hp input. For the Optimal pump, EE motor, the motor ratedhp is the minimum motor size needed to supply the shaft power needed for the optimal pump; theselected size motor includes the margin specified in the Size margin control (at the far right on thescreen).

Shaft power, hpThe shaft power for both the Existing pump, motor and Existing pump, EE motor columns is

calculated from the specified or estimated motor input power and the estimated motor efficiency.

kWe x ηmPsh = ,

74.6

where Psh is the shaft power (hp), kWe is the specified or calculated motor input electrical power, andηm is the motor efficiency in %.

For the Optimal pump, EE motor, the shaft power is calculated from the fluid power at the specified flow rate, head, and specific gravity conditions and the optimal pump efficiency estimate.

Pfl x 100Psh = ,

ηp

where Psh is the shaft power (hp) and ηp is the pump efficiency in %.

If the existing shaft power is greater than rated motor power, the background color in Shaftpower for the Existing pump, motor and Existing pump, EE motor columns changes from gray to redto flag the overloaded motor condition.

Motor efficiencyThe motor efficiency for the Existing pump, motor is calculated from the measured or calculated

motor input power, using the performance characteristics of the specified motor. The motor efficiency for the Existing pump, EE motor is calculated from the shaft power and the performancecharacteristics of an energy efficient motor of the specified size and speed. The motor efficiency forthe Optimal pump, EE motor is calculated from the shaft power needed for the optimal pump withan energy efficient motor of the size calculated and listed in the Motor rated hp result.

Motor power factorThe motor power factor is estimated based on the performance characteristics of the motors.

Power factor is provided for information only and is not used in any other calculations. However, it should be noted that user’s electric bills may include a power factor penalty.

Motor current, ampsIf current is used as the load estimation method, the Existing pump, motor value will be the

same as the input value. If power is used as the load estimation method, the motor current is estimated based on the performance characteristics of the specified motor size, speed, and class.Motor current is not used in any other calculations.

Electric power, kWeFor the Existing pump, motor, the electric power is the measured power or the power calculated

based on measured current. For the Existing pump, EE motor, it is the electric power associated withthe existing shaft power, but with an energy efficient motor used (same as Existing pump, motor if


an Energy efficient motor is specified as the Existing motor class). For the Optimal pump, EE motor,the electric power is that needed to develop the shaft power for the optimal pump application.

Annual energy, MWhrThe annual energy requirement is the product of the electric power and the operating time.

In equation form, it is:

MWhr = kWe x Operating fraction x 8.76.

The operating fraction is over the entire year and the constant converts yr. to hr and kW to MW.

Annual cost, $1,000The annual cost is the product of the annual energy and electrical cost rate:

MWhr x cents/kWhrAnnual cost, in thousands of dollars =

100

Annual savings, $1,000The annual savings is the potential reduction in energy cost relative to the Existing pump, motor

annual cost.

Size margin for optimal pump motorThis control allows the user to specify a motor size margin that is used in selecting the motor

size for the Optimal pump, EE motor condition.

Optimization ratingThe optimization rating is the ratio of the electric power required for the Optimal pump, EE motor

to the Existing pump, motor (expressed as a percentage). A value of 100 represents an existing motorand pump combination whose energy requirements are equal to that for the optimal pump andmotor. The color of the box behind the dial and digital indicator changes according to the generalrating range.

Background information buttonThis button is used to access background information about the operation of this software,

motor, pump, and system efficiency considerations, and discussions of other points of interest relative to pumping system optimization, including distinguishing between measured and requiredconditions.

In this portion of the main screen of PSAT, the user can process (i.e., create, retrieve, delete) logsof screen data. Thus, “log” is used exclusively to refer to a set of data in the main screen of PSATthat can be stored and retrieved back into the main screen as needed.

Log current dataThis button allows the user to log the current screen for subsequent retrieval and viewing. Logs

are stored in individual “log folders” and each folder can contain several “log entries” each of whichfully defines a PSAT main screen. The log folders are useful in grouping data sets by facility, component, process, etc. After clicking on the “Log current data” button, the user is asked to selectan existing folder or create a new one. If a new folder is selected the user is first asked to name it.

Log File Controls


After naming/selecting a log folder, a screen appears with “Evaluator name, data” and“Description” boxes. Changes or additions to these boxes will appear in the log entry listing whenthe data set is retrieved but will not appear in the retrieved main screen of PSAT in either the evaluator’s box or Notes box. Therefore, changes made to them should only be notes to aid inretrieval. Logging is completed by clicking “Continue” or aborted by clicking “Cancel.”

All individual logs are stored in individual log folders contained within the directory called“Logs” which is at in the same location as the PSAT software. ONLY log folders created by PSATshould reside there. The individual log folders can be renamed, moved or deleted using theWindows Explorer interface.

If a log folder is renamed, the log will appear with the new name the next time PSAT is run.

If the log folder is moved to a different location (i.e., outside of the “Logs” directory) using theWindows Explorer, PSAT will no longer recognize the existence of the log. However, if the log folderis subsequently returned to the “Logs” folder, it will once again be recognized.

Of course, if a log folder is deleted, it will no longer be recognized by PSAT.

Retrieve Log dataThis button allows retrieval of previously logged data (see Log current data button above).

The user selects a log folder from the list of available logs and then a screen appears where theuser must click on a log entry number corresponding to the description of the desired data set.Once that selection is made, the main screen of PSAT appears with the retrieved data.

Select a file for individual log deletionSelecting this red deletion button will bring up a listing of logs. After selecting a log folder, a

listing of log entries and corresponding entry numbers will appear. Deletion occurs after selectingthe desired log entry.

The summary file controls allow the user to create and append to summary data files that canbe read later with data base or spreadsheet software. The summary data files contain nearly all ofthe data from the main screen of PSAT with descriptive headings for each.

Create new or append existing summary file This button allows the user to create a new, or add to an existing, tab-delimited file with

summary data from the existing main screen. Summary files can be reviewed and further analyzedusing commercially available spreadsheet or database software programs. This button points to abox to its immediate right that shows what the desired operation will be (e.g., create a new summaryfile or append to the file shown in the box). Thus, the user should be sure that the desired operationis shown in the box before clicking on the button. If CREATE NEW is shown in the box, the userwill be prompted to name the new file. If a file name is shown, the button will append data tothat file and the PSAT main screen will be unchanged (i.e., no box will pop up).

Summary files can be very useful in tabulating the results of PSAT analysis on several pumps.For example, all the pumps in a particular system or facility might be included in an individualsummary file. The summary file could then be copied (or moved) elsewhere with WindowsExplorer to be further analyzed or edited with a spreadsheet or word processing program.

Summary File Controls


The summary files are stored in the directory named “Summaries” which is in the same directory as the PSAT software. If these files are used by another application, such as Excel, themodified files should be stored at some other location; a modified file should never be re-saved tothe original location within the “Summaries” folder.

Existing summary filesThis menu list box allows the user to specify a summary file to which the existing displayed

data will be appended when the “Create new or append existing summary file” button is depressed.

FacilityThe name of the facility can be typed here (used for documentation purposes only).

SystemThe name of the system can be typed here (used for documentation purposes only).

DateThe date of measurement can be typed here (used for documentation purposes only).

ApplicationThe pump application identification can be typed here (used for documentation purposes only).

EvaluatorThe name of the person conducting the evaluation can be typed here (used for documentation

purposes only).

NotesThis space allows notes concerning measurements, equipment condition, etc., to be typed here

(used for documentation purposes only).

The stop button can be used to temporarily suspend program calculations and updating. This may improve processor speed when the user wants to work in another application withoutquitting the PSAT application. As long as the program is in the “running” mode, the stop buttonwill be visible. If it is clicked, it will disappear until calculations are resumed. To resume calculations, click on the arrow just below the File menu in the upper left corner of the screen.

It is important to note that the STOP button must be clicked before exiting the PSAT software.During the “running” mode of operations, the “X” in the standard close box in the upper-rightcorner of the window is grayed ( ); when the STOP button is clicked, the close box will beenabled ( ) and the user can quit PSAT by clicking on the X.

GeneralIdentification

STOP


The “Click for background information” button enables access to a variety of other panels,including operating basis and resource information, as described below.

INFORMATION/TOOLS ACCESSED BY “CLICK FOR BACKGROUND INFORMATION” BUTTON

The “Click for Background Information” button represents a path to much useful informationincluding interactive virtual instruments (VIs) that focus on the pump and motor individually.The PSAT program must be running for the button to work. Figure 3 shows how to navigateamong the different screens and what general topics and interactive charts are available.

The following sections describe the 11 screens that can be accessed beginning with the background information button. Each will be numbered consistent with the screen numberingfound in Figure 3. For text screens, the text is simply reproduced and, for VI screens, a discussion isprovided.

Section Menu List—Screen (1)

Clicking on the background information button brings up a section menu list comprised of thefollowing choices:

General Background—A text screen containing application information and contacts for help.

System measured conditions vs. actual requirements—A text screen describing the goals of the pumpingsystem and a discussion of measured vs. required conditions.

Sources of system losses—A discussion of velocity head and frictional head losses.

Pump efficiency discussion—Takes user to a set of 5 screens (5 through 9 in Figure 3) that addresspump efficiency factors, losses, and performance characterization.

Motor efficiency discussion—Takes user to 2 screens (10 and 11 in Figure 3) for a discussion of motorefficiency factors and motor performance characterization.

General Background—Screen (2)

The PSAT was developed by the DOE’s Office of Industrial Technologies to assist in preliminaryassessments of how efficiently pumping systems are operating.

For many industrial facilities, the energy consumed in pumping fluids comprises a large fractionof the overall facility electricity usage. Operators of pumping systems often are not aware of howeffectively the energy required to pump the fluids is being used.

This tool seeks to provide a relatively simple indication of the pumping system effectiveness.

In essence, the tool simply estimates the work done by the pumping system and compares thatto the estimated energy input into the system. Using generic typical performance characteristicsfor pumps and motors, indications of potential savings (in energy and dollars) are developed.

BackgroundInformation


This tool DOES NOT tell the user how to improve the system. But it does provide a means ofprioritizing energy improvement opportunities.

Accompanying this tool is additional information on factors affecting the various componentsand overall pumping system effectiveness. The user is encouraged to browse through the informationto develop a better understanding of these factors. As these factors are better understood, changesthat can be made to improve system efficiency and effectiveness will often become obvious.

If you have problems or questions about the general operation of PSAT, you can contact the:

OIT Information Clearinghouse e-mail: [email protected] Box 43171 Phone: 1-800-862-2086925 Plum street SE Fax: 1-360-586-8303

Figure 3. Navigating through “background information” screens.


System Measured Conditions vs. Actual Requirements—Screen (3)

The ultimate goal

The foremost opportunity for efficiency improvement in most fluid systems is in what we call theultimate goal.

The ultimate goal of any pumping system is not to just circulate the fluid, but to accomplishsome bigger purpose. For example, if the system is used to remove heat from some process, the ultimate goal of the pumping system might be to keep a process fluid temperature at or below 85°F.If the pumping system were operated to maintain the maximum process temperature at 80°F theoperation would clearly satisfy this ultimate goal. But so would a maximum temperature of 84°F (or85°F for that matter).

Assume that this pumping system is composed of three parallel pumps that remove heat from aprocess and reject it to atmosphere (through cooling towers). Also assume that for a typical summerday, the towers can cool the water in the basin to 75°F. It might be that operation of three parallelpumps with a combined flow rate of 2000 gpm would maintain the 80°F process fluid temperature,while a single pump would operate at a flow rate of 1110 gpm, and at this flow rate would supportan 84°F process condition. Depending on the type of pumps and the nature of the system, the 3-pumpoperation would typically require 2 to 3 times as much energy as the single pump operation. Simplyturning off two of the three pumps would obviously result in considerable energy savings, at least forthe pumping system.a

Clearly, there are other factors to be considered in such situations. For example, reliability factorsmay be much more important in the overall operational framework. It is important to recognizethat these factors are not always competing, in fact at the component level, operation of pumpsnear the pump best efficiency point (BEP) will generally mean improved pump reliability. At the system level, there are often joint actions that can be taken to improve efficiency and reliability.

Measured vs. required conditions

In making an assessment of how well optimized a system is, it is clearly important to not justmeasure the existing system conditions (in particular, the pump flow and head), but to evaluatewhat is really required. In the example discussed above, both operational configurations meet therequirement but analysis of measurements of critical fluid system parameters made at the twoconditions would obviously yield quite different results. Sometimes it is difficult to establish exactlywhat is required, but it is worthwhile to make as accurate an assessment of this requirement aspossible, since it is the benchmark basis on which any optimization effort should proceed. It maynot be practical or even cost effective to actually reach operation at this benchmark condition, butit does provide a clear indication of what is ideally possible.

From information provided in the above example, it could be deduced that the real systemflow rate requirement for the stated summertime conditions is 1000 gpm, since 1000 gpm with aheat exchanger exit temperature of 85°F would reject the same amount of heat to the atmosphereas 2000 gpm with an exit temperature of 80°F.

Sources of System Losses—Screen (4)

The ideal energy required to move a fluid under open, atmospheric conditions is the productof the fluid weight and the elevation through which it is lifted. For example, the ideal energy

aIt is important to recognize that energy and other factors go beyond the pumping system. In the example above, the temperature change on the supported process energy consumption might be to either positive or negative. Therefore, the overall picture needs to be kept in mind, not just the pumping system.


required to lift 10 gallons of water (weighing 83.3 lbs) by 120 feet is 83.3 x 120 = 10000 ft-lbs, or alittle over 3 kilocalories.b

Ideal systems, by definition, have no friction. In real fluid systems, there are many sources offriction, including the piping through which the fluid is moved, pipe components, such as valves,elbows, tees, and internal friction within the fluid. In other words, essentially anything the fluidtouches. In order to overcome these sources of friction additional energy input is necessary. The magnitude of the energy required to overcome the friction is dependent on a variety of factors,including the fluid velocity and viscosity, pipe length, valve(s) type and position, and pipe quality(smoothness).

In fluid systems, the elevation, and equivalent terms associated with pressure and velocity arereferred to as “head” (e.g., elevation head or velocity head). Head, which has units of length (generally in units of feet in the U.S. and meters elsewhere) is defined as the energy per unitweight of fluid. The total head that must be supplied by the pump in a fluid system is that neededto overcome the combination of static (pressure plus elevation) head, frictional head, and velocityhead components. The total fluid power required to move fluid at a given mass flow rate througha system is proportional to the total system head times the flow rate. Obviously, the greater thefrictional head, the greater the energy/power required to overcome it.

One of the things needed by the PSAT in establishing what the system “requires” is the requiredhead. In the case of a real world system, what head should be used? One possibility, in the case ofa system which is dominated by static head, is to simply use the static head (i.e., the elevation pluspressure head).

At the other extreme, where the system is a closed loop, recirculating system, the static headwill be ideally zero, meaning that essentially all of the head to be developed is that needed toovercome friction. What head can be used as the “required” value in such a case?

One way of developing the required head in a closed loop system is to observe the pump headat a known flow rate. Then develop the required head based on the expression:

H(required) = H(measured) x [Q(required)/Q(measured)]2,

where:H(required) = Required headH(measured) = Measured headQ(required) = Required flow rateQ(measured) = Measured flow rate

Pump Efficiency Factors—Screen (5)

The ideal power required to pump a fluid is proportional to the product of the fluid mass flowrate and the pump head. The operating head for a given pump is dictated by the system conditions.The pump flow rate varies with the head. Normally, pump head is plotted as a function of flowrate. This curve, along with shaft power and/or efficiency vs. flow rate and required net positivesuction head vs. flow rate, make up the pump characteristic performance curves. To see typicalpump head, power, and efficiency characteristic curves, click on the “See typical pump performancecurves button” at the right-hand portion of the screen.

b In a closed fluid system, where the fluid may be pumped into a pressurized volume (such as a tank with a nitrogen gas overpressure), the pressure can be converted into an equivalent elevation by the relation:

Equivalent elevation (ft) = Pressure (lbs/square foot) x Fluid specific weight (lbs/cubic foot)

An alternative expression is: Equivalent elevation (ft) = Pressure (psi) x (2.31 x Fluid specific gravity)


One feature to notice in particular is the shape of the pump efficiency curve. It rises from avalue of 0 at no flow (shutoff) to a maximum value at the pump BEP, and then drops off at higherflow rates.

Achievable Efficiency—Screen (6)

Figure 4 shows the screen that is used in determining achievable pump efficiencies based onHydraulics Institute Standard ANSI/HI-1.3. [1] This interactive feature is useful in evaluating theefficiencies for different pump types over ranges of anticipated, required, and/or measured flowrates. It is especially useful in selecting pump styles that will provide the best performance.

When the screen is opened, the defaults for pump style and flow rate are the values selectedon the main screen of PSAT. However, the user may select any pump style in the right-hand boxchoosing from one of the following:

End of suction slurry End suction ANSI/API End of suction sewageAxial flow End of suction stock Double suction vertical turbineAPI double suction Large end suction Multistage boiler feed

By dragging on the red flow rate cursor control at the bottom of the screen (or by typing in thevalue in the numeric box at the right), the desired flow rate can be selected while monitoring theefficiency curves and the numerical readouts of flow rate and achievable efficiencies.

The chart shows both an average and a maximum plot as defined in the ANSI/HI-1.3 Standard.PSAT uses the maximum efficiency (i.e., upper curve) in the results that it produces. The maximumefficiency can be attained in practice if the designer is careful in making pump selections (e.g., minimal but suitable internal clearances exist for the application). Other factors that areimportant are suction conditions, impeller trim, use of packing vs. mechanical seals, and internalsurface roughness.

Figure 4. Acvhievable efficiency plot for selected pump.


It is best to use the linear X-axis mapping unless there is some need for better resolution at lowflow/low efficiency conditions for which the logarithmic mapping is best.

Achievable Efficiency Penalty vs. Specific Speed—Screen (7)

The interactive screen shown in Figure 5 relates specific speed and efficiency penalty. It isderived from the Hydraulics Institute Standard ANSI/HI-1.3 [1] (as was the achievable efficiencygraph). Assuming that specific speed is understood (see next topic), then the graph will clearlydepict this relationship and is easy to use. Similar to the achievable efficiency graph, the screenopens with the same flow rate that is selected in the main screen of PSAT. Another similarity isthat the specific speed may be selected at the bottom of the screen using the specific speed cursoror numeric control. The results are presented by the (1) curve, (2) numeric value in the specificspeed box, and (3) efficiency penalty box.

Specific Speed Discussion—Screen (8)

Specific speed is defined as follows:

N√QNs = specific speed H = head (per stage)

Ns = Where: N = rotational speed g = acceleration due to gravity(gH)0.75

Q = flow rate

If consistent units are used for these units, specific speed is a dimensionless parameter. Whenthe appropriate units are used, it is a dimensionless quantity.

However, standard industry practice (both in the U.S. and abroad) is to use common engineeringunits that do not resolve to a dimensionless quantity. In the U.S., the standard units used to calculatespecific speed are rotational speed in rpm, flow rate in gpm, and head in feet per stage.

Figure 5. Achievable efficiency penalty vs. specific speed.


It is also standard practice to eliminate the gravitational constant term resulting in the following:

N√QNs =

(H)0.75

The specific speed equation is to be applied to only one condition, namely the BEP. An examplecalculation of specific speed is shown below (in U.S. units):

1780√5000Ns = = 3472

(120)0.75

Most centrifugal pumps in common industrial applications have specific speed values (U.S. units)between 500 and 7000. Impellers toward the lower end of the range have a pronounced radialprofile, while impellers toward the upper end of the range approach axial flow.

Typical Pump Curves—Screen (9)

Figure 6 shows a plot of head vs. flow rate. Plots of power vs. flow rate and efficiency vs. flowrate can also be selected using the Parametric plot selection box above the graph. The curves areprovided for general information for those interested in seeing typical examples of these types ofplots and how the three selected parameters change with increasing flow rate.

Single stage pump, rotating speed = 1780 rpm,BEP flow rate, head = 5000 gpm, 120 feet

Figure 6. Typical pump curve.


Motor Efficiency Factors—Screen (10)

While there are certainly improvements in efficiency and savings in operational costs to begained from the use of premium efficiency motors, the potential rewards are usually much lessthan those available from optimizing the pump and system which rely on the power provided bythe motor.

NEMA MG-1 prescribes standards which motor efficiency must exceed in order to be classifiedas “energy efficient.” To develop an idea about the potential energy savings that could accrue byusing an energy efficient motor instead of a standard efficiency motor, motors in the MotorMaster+database were distributed into two categories: those exceeding MG-1 Table 12-10 specificationsand those not meeting those specifications. The average efficiency and power factor performancecharacteristics vs. motor load of these two groups were then developed.

From these average characteristics, curve fits of the motor power, current, efficiency, and powerfactor characteristics across the performance range can be developed. From these fits, an estimateof the performance characteristics of standard and energy efficient motors can be readily identifiedat any load level. This approach forms the basis for estimating the motor efficiency, shaft power,and other parameters in the PSAT.

Motor Performance—Screen (11)

Figure 7 presents the screen for the motor performance vi. This vi can be used to optimize apump application by fine-tuning the motor parameters or experimenting with different motortypes. More generally, the vi can be used for making selections in any type of motor applications(i.e., unrelated to pump applications). The curves and numerical data are based on theMotorMaster+ [3] database. MotorMaster+ was developed by the DOE’s OIT and the motor data is based on a comprehensive survey of vendor data on all classes of electric motors.

Figure 7. Interactive plot of motor performance.

21Pumping System Assessment Tool User Manual

The color and symbol legend for the curves (i.e., at top left in Figure 7) define each curve asdepicting either percent full load amps (FLA) vs. load, percent power factor (PF) vs. load, or percent efficiency vs. load. Input values are nameplate hp, speed (rpm), rated voltage, and motorclass. The output from the VI is shown in the (1) curves; (2) full load amps box midway along theleft side of the screen, and (3) table in the lower left screen. The table indicates percent full loadamps (FLA) vs. load, percent power factor (PF) vs. load, or percent efficiency vs. load at four loadconditions, 25%, 50%, 75%, and 100%.

To obtain data at other load levels the plot cursor bars can be positioned on any one of the three curves to produce the exact numericalvalues. Note the symbol of diamonds just to the right of the table.Clicking the left and right diamonds moves the cursor bars in the corresponding direction. To move the cursor bars onto another curve, go tothe small padlock symbol under the diamonds (see Fig. 8) and click it. Themost useful choices to use from the list are:

—% FLA fit—% pf fit—% efficiency fit

As the user moves the cursor bars along any curve, the load percentageand the selected item’s value appear in the boxes to the left of the padlocksymbol (load = 92.0% and efficiency fit = 95.3% in Fig. 7).

The user can change the hp, synchronous speed, rated voltage, and motor class to see thechange in performance. However, it is suggested that the shape of the curves for various selectedmotors may generally be even more instructive than the actual numerical percentage values atgiven loads. As with all software of this type, experimentation and exploration of the software isencouraged and will likely reveal other useful features of interest for one’s own applications.

REFERENCES

1. Centrifugal Pump Design and Application, ANSI/HI 1.3-1994, Hydraulic Institute.

2. Efficiency Prediction Method for Centrifugal Pumps, Hydraulic Institute, Parsippany, New Jersey, 1994.

3. MotorMaster+ Software Program, Web page: http://mm3.energy.wsu.edu/mmplus

4. Full-Load Efficiencies of Energy Efficient Motors, NEMA MG 1-1993, Section II, Part 12, Table 12-10.

Figure 8. Plot selection.

Text authored byDonald A. Casada and Robert H. Staunton

Oak Ridge National LaboratoryORNL/TM-1999/215

OFFICE OF INDUSTRIALTECHNOLOGIES

OFFICE OF INDUSTRIAL TECHNOLOGIESENERGY EFFICIENCY AND RENEWABLE ENERGY • U.S. DEPARTMENT OF ENERGY

FOR ADDITIONAL INFORMATION, PLEASE CONTACT:

The OIT ClearinghousePhone: (800) 862-2086Fax: (360) 586-8303

Please send any comments,questions, or suggestions [email protected]

Visit our home page atwww.oit.doe.gov.

Office of Industrial TechnologiesEnergy Efficiencyand Renewable EnergyU.S. Department of EnergyWashington, DC 20585

February 2000

Pumping SystemAssessment ToolUser Manual

Prepared by the Oak Ridge National Laboratory, managed by Lockheed Martin Energy ResearchCorporation for the U.S. Department of Energy under contract number DE-AC05-96OR22464.

The submitted manuscript has been authored by a contractor of the U.S. Government under con-tract DE-AC05-96OR22464. Accordingly, the U.S. Government retains a non-exclusive, royalty-freelicense to publish or reproduce the published form of this contribution, or allow others to do so,

for U.S. Government purposes.

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