OFFICE OF

W E I G H T S A N D 

M E A S U R E S

Examination Procedure Outlines for 

Commercial Weighing and Measuring Devices

 A Manual for Weights and Measures Officials 

NIST 

Handbook 112 

2002 Edition
iii

FOREWORD 

National Institute of Standards and Technology (NIST) Handbook (HB) 112, "Examination Procedure Outlines 

(EPOs) For Commercial Weighing and Measuring Devices," was first published in 1973 by the National Bureau of 

Standards, Weights and Measures Program, which is now the NIST Office of Weights and Measures (OWM). NIST 

developed these EPOs and compiled them into this handbook to serve as a guide for the field examination of 

commercial weighing and measuring devices. It includes inspection and test procedures, with code references to 

NIST HB 44, “Specifications, Tolerances, and Other Technical Requirements for Weighing and Measuring 

Devices.” 

The EPOs in this document have been updated to include references to the 2002 edition of NIST HB 44 and to 

recognize electronic equipment. A new EPO for compressed natural gas retail motor fuel dispensers has been 

added. Some of the EPOs that appeared in the original version of NIST HB 112 have not been updated and are not 

included in this document. 

Although this publication was prepared primarily for use by weights and measures officials of the Federal, State, and 

local jurisdictions, it should also be useful to manufacturers and other commercial and industrial organizations and 

individuals involved in the design, sale, service, or use of weighing and measuring devices. 

This handbook conforms to the concept of primary use of SI (metric) measurements recommended in the Omnibus 

Trade and Competitiveness Act of 1988 by citing SI units before inch-pound units where both units appear together 

and placing separate sections containing requirements in SI units before corresponding sections containing 

requirements in inch-pound units. In some cases, however, common trade practice is currently restricted to the use 

of inch-pound units; therefore, some examples in this Handbook will continue to specify only inch-pound units until 

the industry achieves a broad consensus on the permitted SI units. 

In accord with NIST policy, the meter/liter spellings are used in this document. 
v

TABLE OF CONTENTS 

 Page 

Foreword............................................................................................................................................................iii 

Acknowledgements ...........................................................................................................................................iv 

Introduction .......................................................................................................................................................vi 

Safety Considerations........................................................................................................................................vii 

References .........................................................................................................................................................ix 

EPO No.

Scales 

1 Retail Computing Scales ..............................................................................................................1-1 

7/8 Medium Capacity Scales..............................................................................................................7/8-1 

9 Mechanical Meat Beams and Monorail Scales ............................................................................9-1 

9E Monorail Scales Equipped with Electronic Digital Indicators .....................................................9E-1 

12 Livestock and Animal Scales Mechanical-Analog Indicating......................................................12-1 

12E Livestock and Animal Scales Equipped with Electronic Digital Indicators.................................12E-1 

13 Vehicle and Axle-Load Scales Mechanical-Analog Indicating 

(Weighbeams and Dials) ..............................................................................................................13-1 

 13E Vehicle and Axle-Load Scales Equipped with Electronic Digital Indicators...............................13E-1 

 

Meters 

 21 Retail Motor-Fuel Dispensers Single, Dual, and Multi-Product ..................................................21-1 

 22 Retail Motor-Fuel Dispensers Blended Product...........................................................................22-1

 23 Vehicle-Tank Meters Power-Operated.........................................................................................23-1 

 24 Vehicle-Tank Meters Gravity-Discharge .....................................................................................24-1 

 25 Loading-Rack Meters...................................................................................................................25-1 

 26 Liquefied Petroleum Gas Motor-Fuel Dispensers........................................................................26-1 

 27 Liquefied Petroleum Gas Liquid-Measuring Devices..................................................................27-1 

 28 Compressed Natural Gas Retail Motor-Fuel Dispensers..............................................................28-1 

Glossary of Safety Key Phrases.........................................................................................................................G-1 
vi

INTRODUCTION 

This handbook contains Examination Procedure Outlines (EPOs) for the field examination of commercial weighing 

and measuring devices. It includes inspection and test procedures, with code references to National Institute of 

Standards and Technology Handbook 44 “Specifications, Tolerances, and Other Technical Requirements for 

Weighing and Measuring Devices”, 2002 Edition. A reference that begins with the letter “G” refers to the General 

Code; all others refer to the specific code noted at the beginning of the EPO. 

Each outline contains five sections: (1) Safety notes and safety key words or phrases; (2) an Inspection section, 

which covers design, installation, and user requirements that must be met; (3) a Pretest Determinations section, 

which addresses the determination of tolerances and other factors that should be established prior to testing; (4) a 

Test Notes section, which covers actions to be taken throughout the test or testing information of a general nature; 

and (5) a Test section, which gives a step-by-step procedure for determining a device’s compliance with applicable 

performance requirements. An Equipment section is included in the EPO for compressed natural gas (CNG) only. 

Similar sections may be added to other EPOs as they are updated in future editions of this Handbook. 

EPO users should remember that each outline describes the minimum examination preceding official action. An 

official may perform additional test not described in this handbook, or may repeat any or all tests as part of the 

examination process. Many factors influence the nature and extent of an examination. Some cases might require a 

more extensive examination, such as the first examination of a device after it has been placed into commercial 

service. Consequently, users of these EPOs should thoroughly familiarize themselves with all of the requirements in 

Handbook 44 that are applicable to a device under inspection to ensure a thorough inspection. 
vii 

SAFETY CONSIDERATIONS

NOTE: When excerpting an Examination Procedure Outline for duplication, this section and the "Glossary" 

located in the back of this publication should also be duplicated and included with the outline. 

The importance of safety in the weights and measures workplace cannot be overemphasized. During the inspection and 

testing of weighing and measuring equipment, the issue of safety should be foremost in the inspector's or 

serviceperson's mind. It is only through conscientious adherence to safety regulations and procedures on a regular basis 

that the inspector or serviceperson can decrease the likelihood of causing serious personal injury, injury to individuals 

in and around the inspection area, or damage to property and equipment. Safety-consciousness must also extend to the 

selection and maintenance of testing equipment and other equipment used by an inspector or serviceperson. 

Weighing and measuring equipments differ in design, and the safety of their use may be affected by other factors in the 

workplace such as ignition sources, environmental influences and characteristics of the individual installation. Because 

of this variability, it is impractical to make specific recommendations that will identify or address safety hazards that 

may be present in a particular jurisdiction. In order to properly address the safety hazards that may be present during an 

inspection activity, a jurisdiction should consider the following steps in working to minimize the hazards: (1) conduct a 

job hazard analysis; (2) determine what safety and health training is needed; (3) determine the control (administrative, 

engineering, and personal protective) needed; (4) provide a written safety and health program; and (5) enforce the 

policy. 

Before proceeding with the inspection and testing of a weighing or measuring device, the inspector or serviceperson 

should be completely familiar with all safety regulations and policies in effect at the inspection location. Such 

regulations and policies include state, Federal, or local Occupational Safety and Health Administration (OSHA) 

regulations, safety policies established by the firm in which the inspection is taking place or established by the 

inspector's or serviceperson's employer. 

The Examination Procedure Outlines (EPOs) in this publication address a wide variety of activities involving the 

inspection and testing of various types of weighing and measuring equipment. Each of these inspection activities 

requires knowledge of safety information specific to the inspection of that device. A brief paragraph at the beginning 

of each EPO reminds the inspector or serviceperson of some of the basic safety precautions, which should be taken 

prior to proceeding with the inspection procedure. Also, safety reminders are included at various points throughout the 

body of the EPO. The safety reminders use "key phrases" to prompt the inspector or serviceperson to remember 

particular safety precautions. A glossary of these key phrases is included at the back of this publication. The glossary 

provides a brief explanation of the intent of the safety precaution and, in some cases, provides a listing of a source or 

sources where additional information might be obtained pertaining to a particular safety concern. 

The safety reminders included in this publication are not intended to cover all possible safety precautions that should be 

taken before proceeding with the inspection of a weighing or measuring device. (Similarly, the safety information and 

contacts are not a complete listing of all possible sources of information and guidance in the area of safety.) The safety 

reminders are intended to raise the awareness of the weights and measures inspector or serviceperson, and to serve as a 

reminder to make safety an integral part of all inspection and testing procedures. The safety reminders are also 

intended to encourage the inspector or serviceperson to thoroughly investigate the safety requirements in effect at an 

inspection site and to identify and practice the safety procedures necessary to prevent personal injury, injury to others, 

or damage to equipment and property during the inspection. 

For additional information on safety in the weights and measures workplace and the development of a safety program, 

see the July 1991 Final Report of the NCWM Task Force on Safety. 
viii

Safety policies and regulations vary among jurisdictions. It is essential that inspectors or servicepersons be aware 

of all safety regulations and policies in place at the inspection site and to practice their employer’s safety policies. 

The safety reminders included in this EPO contain general guidelines useful in alerting inspectors and 

servicepersons to the importance of taking adequate precautions to avoid personal injury. These guidelines can only 

be effective in improving safety when coupled with training in hazard recognition and control. 
ix

REFERENCES 

National Institute of Standards and Technology (NIST) Handbook (HB) 44, 2002, Specifications, Tolerances and 

Other Technical Requirements For Weighing and Measuring Devices, Tina Butcher, Terry Grimes, Richard Suiter, 

Juana Williams 

National Conference on Weights and Measures (NCWM) Publication 14, latest version, National Type Evaluation 

Program Administrative Procedures, Technical Policy, Checklist, and Test Procedures

National Bureau of Standards HB 94, 1965, The Examination of Weighing Equipment, Malcolm W. Jensen and 

Ralph W. Smith 
Retail Computing Scales

EPO No. 1

Rev 3/02 1-1 

 

Examination Procedure Outline for

Retail Computing Scales

It is recommended that this outline be followed for electronic digital indicating and mechanical analog-indicating retail 

computing scales and prepackaging scales. Requirements that apply only to scales marked with an accuracy class are 

indicated with an asterisk. Non-retroactive requirements are followed by the applicable date in parentheses. 

SAFETY NOTES 

When excerpting this Examination Procedure Outline for duplication, the "Safety Considerations" section and the 

"Glossary of Safety Key Phrases" should be duplicated and included with the outline. 

The inspector is reminded of the importance of evaluating potential safety hazards prior to an inspection and taking 

adequate precautions to avoid personal injury or damage to the device. The inspector should read and be familiar with 

the introductory section on safety “Safety Considerations”found at the beginning of this publication. As a minimum, the 

following safety precautions should be noted and followed during the inspection. Definitions of each reminder are found 

in the "Glossary of Safety Key Phrases" at the back of this publication. 

Safety policies and regulations vary among jurisdictions. It is essential that inspectors or servicepersons be aware of 

all safety regulations and policies in place at the inspection site and to practice their employer’s safety policies. The 

safety reminders included in this EPO contain general guidelines useful in alerting inspectors and servicepersons to 

the importance of taking adequate precautions to avoid personal injury. These guidelines can only be effective in 

improving safety when coupled with training in hazard recognition and control. 

 Electrical Hazards Personal Protection Equipment 

 e.g., Safety Shoes 

 First Aid Kit 

 Support – for Scale and Test Weights 

 Lifting 

 Transportation of Equipment 

 Location 

 

 also: Wet/Slick Conditions 

 Chemicals, Petroleum Products, and Hazardous Materials 

 Obstructions 
Retail Computing Scales

EPO No. 1 

Rev 3/02 1-2 

Inspection: 

Safety First!!! 

Check the inspection site carefully for safety hazards and take appropriate precautions. 

Learn the nature of hazardous products used at or near the inspection site. 

Use personal protection equipment appropriate for the inspection site. 

Be sure that a first aid kit is available and that the kit is appropriate for the type of inspection activity. 

 H-44 General Code and 

 Scales Code References

1. Zero-load balance as found. For pre-packaging scale, 

check to determine if tare is being taken.......................................................................S.1.1., UR.4.1., S.2.1.1., 

S.2.1.2.,G-S.5.2.2.(d) (1/1/86) 

2. General Considerations 

 Selection.................................................................................................................G-UR.1.1. 

 Installation...............................................................................................................G-UR.2.1.,G-UR.2.2., UR.2.2. 

 Supports and clearance............................................................................................UR.2.1., UR.2.4. 

Check to be sure the scale supports are adequate to support 

the scale and test weights equal to the capacity of the scale !

 Accessibility for inspection, testing, and sealing....................................................G-UR.2.3. 

 Testing devices at a central location.......................................................................G-UR.4.6. 

 Assistance...............................................................................................................G-UR.4.4. 

 Position, customer readability ................................................................................G-UR.3.3., S.1.8.3. 

 Level indicating means and condition ....................................................................S.2.4., UR.4.2. 

 Maintenance, use, and environmental factors 

 (cleanliness, obstructions, modifications, etc.).......................................................G-S.2.,G-UR.1.2., G-UR.3.1., 

G-UR.3.2., 

UR.3.5.,G-UR.4., UR.2.3., 

UR.4.3. 

3. Marking .........................................................................................................................S.6.3., G-S.5.2.4, S.5.1., S.6.2 

a. Marking requirements - all devices 

 Identification ..........................................................................................................G-S.1.

 Name or ID of manufacturer................................................................................Retroactive 

 Model designation ...............................................................................................Retroactive 

 Model prefix ........................................................................................................(1/1/03) 

 Nonrepetitive serial number ................................................................................(1/1/68) 

 

Inspection (cont.): 
Retail Computing Scales

EPO No. 1 

Rev 3/02 1-3 

 Marking requirements - all devices (cont.)

 Identification (cont.)...............................................................................................G-S.1.

 Serial number prefix ............................................................................................(1/1/86)

NTEP CC prefix and number ..............................................................................(1/1/03) 

 (for devices that have an NTEP CC) 

Remanufacturer information, as appropriate .......................................................G-S.1.1. 

 name and ID of remanufacturer.......................................................................(1/1/02) 

 model number if different from original model number..................................(1/1/02) 

 Lettering .................................................................................................................G-S.7. 

 Operational controls, indications, and features.......................................................G-S.6. (1/1/77) 

 Visibility of identification ......................................................................................G-UR.2.1.1. 

 Interchange or reversal of parts ..............................................................................G-S.4. 

 b. Marking requirements - weighing and indicating elements in same housing or covered on the same CC 

 (in addition to marking for all devices) ....................................................................S.6.3. 

 Accuracy class........................................................................................................(1/1/86) 

 Nominal capacity....................................................................................................Retroactive 

 Value of scale division with nominal capacity, if not apparent..............................(1/1/83) 

 Value of "e" (if different from "d") ........................................................................(1/1/86) 

 Temperature limits if other than -10 0

C to 40 0C (14 0F to 104 0F)........................(1/1/86) 

 Scales designed for special purposes......................................................................(1/1/86) 

 c. Marking requirements - indicating element not permanently attached or covered on separate CC 

 (in addition to marking for all devices) ....................................................................S.6.3. 

Accuracy class........................................................................................................(1/1/86) 

 Nominal capacity....................................................................................................Retroactive 

 Value of scale division with nominal capacity, if not apparent..............................(1/1/83) 

 Value of "e" (if different from "d") ........................................................................(1/1/86) 

 Temperature limits if other than -10 0

C to 40 0C (14 0F to 104 0F).........................(1/1/86) 

 Scales designed for special purposes......................................................................(1/1/86) 

 Maximum number of scale divisions (nmax)............................................................(1/1/88) 

 d. Marking requirements - weighing and load receiving element not permanently attached or covered on separate 

 CC (in addition to marking for all devices)..............................................................S.6.3. 

 Accuracy class........................................................................................................(1/1/86) 

 Nominal capacity....................................................................................................Retroactive 

 Temperature limits if other than -10 0

C to 40 0C (14 0F to 104 0F).........................(1/1/86) 

 Scales designed for special purposes......................................................................(1/1/86) 

 Maximum number of scale divisions (nmax)............................................................(1/1/88) 

 Minimum verification scale division for which device complies 

 with the requirements (emin or d).............................................................................(1/1/88) 

e. Marking requirements - load cell with Certificate of Conformance 

 (in addition to marking for all devices) ....................................................................S.6.3. S.5.4. (1/1/94) 

Note: Requires information on a data plate attached to the load cell or in 

 an accompanying document. If a document is provided, the serial number shall 

 appear on the load cell and in the document...........................................................(1/1/88) 

 Manufacturer’s name or trademark, model designation, model prefix, and serial 

 number and prefix shall also be marked on both the load cell and in any 

 accompanying documents.......................................................................................(1/1/91) 

Inspection (cont.): 
Retail Computing Scales

EPO No. 1 

Rev 3/02 1-4 

 Marking requirements - load cell with Certificate of Conformance (cont.)...................S.6.3. S.5.4. (1/1/94) 

 Accuracy class........................................................................................................(1/1/88)

 Temperature limits if other than -10 0

C to 40 0C (14 0F to 104 0F)........................(1/1/86) 

 Maximum number of divisions...............................................................................(1/1/88) 

 “S” or “M” for single or multiple cell applications ................................................(1/1/88) 

 Direction of loading, if not obvious........................................................................(1/1/88) 

 Minimum dead load, maximum capacity, safe load limit, and load cell 

 verification interval, vmin ........................................................................................(1/1/88) 

 

4. Indicating and recording elements. 

 Value of scale division ...........................................................................................S.1.2.* (1/1/86), S.1.2.1. 

(1/1/89), S.1.2.2., S.5.3., 

UR.1.1.(b), G-S.5.3., GS.5.3.1.,U.R.1.3. (1/1/86) 

 Prepackaging scales only.....................................................................................S.1.9.1. 

 Value of tare division .............................................................................................S.2.3. (1/1/83) 

 Tare mechanism .....................................................................................................S.2.3. 

 Combined zero-tare (“0/T”) key.............................................................................S.2.1.6. 

 Appropriateness of design ......................................................................................G-S.3., G-S.5., S.1.3., 

S.1.4.,S.1.8.1., 

S.1.8.2.,S.5.2.*(1/1/86), 

S.1.8.3.1 (1/10/01), S.5.4 

 Prepackaging scales only.....................................................................................S.1.9.2. 

 Suitability for use ...................................................................................................UR.1.,UR.1.1., UR.3.1.*, 

UR.3.2.,G-UR.1.1. 

 Damping means......................................................................................................S.2.5. 

 Adjustable components ..........................................................................................S.1.10. 

 Provisions for sealing .............................................................................................S.1.11.(a) (1/1/79), S.1.11.(b) 

(1/1/90), S.1.11(c) (1/1/95), GUR.4.5.,G-S.8.(1/1/90), S.1.8.3.1. 

(1/1/01) 

5. Weighing elements 

 Antifriction means..................................................................................................S.4.1. 

 Adjustable components ..........................................................................................S.4.2. 

 Multiple load-receiving elements...........................................................................S.4.3. 

 Drainage, if wet commodities are weighed ............................................................S.3.2., UR.3.6. 

 Scoop counterbalances ...........................................................................................S.3.3. 

Pretest Determinations:

Tolerances. 

1. Acceptance/maintenance ...............................................................................................G-T.1., G-T.2. 

2. Application ....................................................................................................................G-T.3. 
Retail Computing Scales

EPO No. 1 

Rev 3/02 1-5 

Pretest Determinations (cont.):

3. Tolerance values: 

 Determine number of scale divisions (n)1 ............................................................n = Scale capacity 

 Value of scale division 

 If scale is marked with an accuracy designation.....................................................T.N.2.1.,T.N.2.3., T.N.2.4., 

T.N.3.1./ Table 6 (Class III), 

T.N.3.2., T.N.4.4., T.N.5. 

 If scale is unmarked but n equals 5000 or less .......................................................T.1.1.,T.N.2.1., T.N.2.3., 

T.N.2.4.,T.N.3.1./Table 6 (Class

 III),T.N.3.2., T.N.4.3., 

T.N.5. 

 Unmarked postal & parcel post scales....................................................................T.1.2. 

 Discrimination........................................................................................................T.N.7.1, T.N.7.2., 

N.1.5.(1/1/86), N.1.5.1 

Test Notes:

1. Check repeatability of, and agreement between, indications throughout test. ...............G-S.5.2.2.(a), T.N.5., 

 G-S.5.4. 

2. Recheck zero-load balance each time test load is removed. ..........................................N.1.9., G-UR.4.2. 

3. If scale is equipped with a printer, print ticket 

or label at each test load. Check effectiveness 

of motion detection, and check labels and weight 

and money value agreement..........................................................................................G-S.5.2.2.,G-S.5.5., 

G-S.5.6.,S.2.5.1.(b), 

S.1.8.2.,S.1.8.4., UR.1.3. 

(1/1/86) 

4. Electronic scales only - If, during the conduct of 

the test, the performance of the device is 

questionable with respect to the zone of uncertainty 

or the width of zero (see test procedure below), adequate tests should be 

conducted to determine compliance..............................................................................N.1.5. (1/1/86), N.1.5.1., 

S.1.1.1.(a), S.1.1.1.(b) (1/1/93) 

 

 

1 On a multiple range or multi-interval scale the number of divisions for each range independently shall not exceed the 

maximum specified for the accuracy class. The number of scale divisions, n, for each weighing range is determined by 

dividing the scale capacity for each range by the verification scale division, e, for each range (i.e., do not add “n” for 

the ranges together). On a scale system with multiple load receiving elements and multiple indications each element 

considered shall not independently exceed the maximum specified for the accuracy class if the system has a summing 

indicator, the nmax for the summed element shall not exceed the maximum specified for the accuracy class. (Table 3 

footnote added 1998).
Retail Computing Scales

EPO No. 1 

Rev 3/02 1-6 

Test Notes (cont.): 

This example of Auto Zero and the Width of Zero test is based on a scale 

division of 0.01 lb. The principles used in this example can also be used to 

test scales with other division sizes, including scales indicating in metric 

units. 

Auto zero: 

Test action Indication

a. Zero scale .00 

b. Appy 0.007 +.01 

(Repeat three times. Three failures will result in scale rejection.) 

c. Zero scale .00 

d. Apply 0.007 +.01 

e. Zero Scale .00 

f. Remove 0.007 -.01 or a below zero indication 

(Repeat three times. Three successive failures will result in scale 

rejection. If scale passes go to the next test) 

Width of zero: 

Test action Indication

a. Zero scale .00 

b. Apply 0.007 +.01 

c. Zero scale .00 

d. Remove 0.007 -.01 or a below zero indication. 

e. Apply 0.015 +.01 Stable 

(Note: The scale should pass this test with 0.013. The 0.002 is added to 

recognize field environments. Three successive failures will result in 

rejection.) 

Apply or remove weights all at once in both tests. Use forceps if 

necessary. 

5. Electronic scales only - If the device is equipped 

 with operational features such as programmable tare 

 and/or unit prices, multiplier keys, sales accumu- 

 lation, manual weight entries, price retention, or 

 two scales with one printer, check proper operation 

 and appropriateness.......................................................................................................G-UR.4.1., G-UR.4.2., 

S.4.3.,S.1.12.(1/1/93), UR.3.9. 

Test for Electronic Scales: 

WEAR SAFETY SHOES !

USE PROPER LIFTING TECHNIQUES !

+.01

.008

.007

.006

.005

.004

.003

.002

.001

0

.001

.002

.009

.003

.004

.005

.006

.007

.008

.009

-.01

Zone of

uncertainty

‹ .3 d

(T.N.7.2.)

Zone of

uncertainty

‹ .3 d

(T.N.7.2.)

Width of

zero

± 1⁄2 d

(S.1.1.1.)

Maximum

range of

automatic

zero tracking

± .6 d

(S.2.1.3.)

B = Breakpoint

B

B

B

B

Center

of zero

± 1⁄4 d

(S.1.1.1.)
Retail Computing Scales

EPO No. 1 

Rev 3/02 1-7 

Test for Electronic Scales (cont.):

1. Test for discrimination at zero load (if environmental conditions permit).....................N.1.5. (1/1/86), N.1.5.1. 

This example of a discrimination test at zero load is based on a scale 

division of 0.01 lb. The principles used in this example can also be 

used to test scales with other division sizes, including scales 

indicating in metric units.

a. With the devices at zero, place decimal weights on scale 

equal to 1 d. 

b. Zero the scale and place a test load equal to 5 d on the load 

receiver. 

c. Remove the decimal weights in 0.1 d increments until the 

indication flickers between 0.04 lb. and 0.05 lb. If the 

indication does not flicker but indicates a steady 0.04 lb, add 

0.1 d. If the scale indicates 0.05 lb, it is at the breakpoint in 

the zone of uncertainty. (remove the 0.1 d if it was used to 

verify the breakpoint.) 

d. Add a test load equal to 1.4 d. to the scale (0.014 lb) 

e. The indication should read a steady 0.06 lb. 

f. If the scale passes this test at a load near zero, the test should 

be performed near the maximum test load. 

2. Increasing-load test2 (with the load centered) 

 at the following minimum test loads (20d): 

 For scales indicating in metric units: 

 100 grams; then at each 500 grams to 2.5 kilograms; at 2.5-kilograms 

 intervals thereafter to one-half scale capacity (include 

 500d, 2000d, and 4000d). ..............................................................................................N.1.1. 

 

 For other scales: 

 0.50 pound; then at each pound to 5 pounds; at 5 pound intervals thereafter to one-half 

 scale capacity (include 500d, 2000d, and 4000d) ..........................................................N.1.1. 

 

2 For scales that are not marked with an accuracy classification and have less than 1000 scale divisions, use the 

following procedure: begin test at 20 d then test at 0.50 pound and at each pound to capacity, including 1/4, 1/2, and 3/4 

capacity.

.06

.008

.007

.006

.005

.004

.003

.002

.001

.05

.009

.008

.009

.007

.006

.005

.004

.003

.002

.001

.04

Zone of

uncertainty

‹ .3 d

(T.N.7.2.)

Zone of

uncertainty

‹ .3 d

(T.N.7.2.)

W idth of

division

This line

represents a

test load of

1.4 d applied to

a scale which is

at the lower

edge of the zone

of uncertainty

between

0.04 and 0.05

B = Breakpoint

B

B

B

B
Retail Computing Scales

EPO No. 1 

Rev 3/02 1-8 

Test for Electronic Scales (cont.):

3. Shift test--one-half capacity load...................................................................................N.1.3.1.

4. Continue increasing-load test: 

 For scales indicating in metric units - at 2.5-kilograms to capacity 

 For other scales – at 5-pound intervals to capacity. 

5. RFI/EMI tests (if a problem is suspected) 

 Radio Frequency Interference (RFI) 

 Electromagnetic Interference (EMI) at capacity............................................................G-UR.1.2.,G-N.2., G-UR.3.2., 

G-UR.4.2., 

 N.1.6., T.4., T.N.9.* 

6. Test for over-capacity indication. ..................................................................................S.1.7. 

7. Test for discrimination at capacity (if environmental conditions permit). .....................N.1.5. (1/1/86), N.1.5.1. 

A test load equivalent to 1.4d shall cause a change in the 

indicated or recorded value of at least 2.0d. .................................................................T.N.7.2. 

Test Weight

Position

1

4

5

2

3

Bench and Counter Scale
Retail Computing Scales

EPO No. 1 

Rev 3/02 1-9 

Test for Electronic Scales (cont.): 

This example of a discrimination test near capacity is based on a scale 

division of 0.01 lb at a test load of 29.00 lb. The principles used in this 

example can also be used to test scales with other division sizes and 

capacities, including scales indicating in metric units. 

a. With the scale at zero, add decimal weights equal to 1.4 d and 

zero the device. 

b. Add test weights to make the scale indicate a weight value 

near capacity (e.g., 29.00 lb) 

c. With the scale stable, add decimal weights in 0.1 d 

increments until the indication flickers between 29.00 lb 

and 29.01 lb. If the indication shows a steady 29.01 lb., 

remove 0.1 d. If the scale indicates 29.00 lb it is at the 

breakpoint in the zone of uncertainty. (Replace the 0.1 d if 

it was used to verify the breakpoint) 

d. Remove the 1.4 d test load (0.014 lb.) 

e. The scale should indicate a steady 28.99 lb. 

f. If the test passes near the maximum capacity, the test should 

be performed near zero. 

8. Decreasing-load test--for scales marked with an accuracy class and having 1000 

 or more scale divisions (d), test with loads equal to the maximum test load at each 

 tolerance value. For example, on a Class III scale, at test loads equal to 4000d, 

 2000d, and 500d; for scales with n less than 1000d, the test load shall be equal to 

 one-half of the maximum load applied in the increasing-load test. ...............................N.1.2., N.1.2.1., or N.1.2.2. 

9. Recheck zero-load balance ............................................................................................N.1.9., G-UR.4.2. 

10. Test for proper design of automatic zero-setting mechanism, 

 if scale is so equipped....................................................................................................S.2.1.3.(a) (1/1/81) 

 Under normal operating conditions the maximum load that can be “rezeroed” when 

 placed on or removed from the platform all at once, shall be 0.6 scale division. 

11. Check proper design of tare auto-clear, if scale is so equipped. ....................................S.2.3. (1/1/83) 

Test for Electronic Scales (cont.):

29.01

.008

.007

.006

.005

.004

.003

.002

.001

29.00

.009

.008

.009

.007

.006

.005

.004

.003

.002

.001

28.99

Zone of

uncertainty

‹ .3 d

(T.N.7.2.)

Zone of

uncertainty

‹ .3 d

(T.N.7.2.)

W idth of

division

This line

represents a test

load of

1.4 d rem oved

from a scale

which is at the

upper edge of

the zone of

uncertainty

between

29.00 and

29.01

B = Breakpoint

B

B

B

B
Retail Computing Scales

EPO No. 1 

Rev 3/02 1-10 

12. If scale is equipped with a semi-automatic zero-setting mechanism, test effectiveness 

 of motion detection........................................................................................................S.2.1.2.(b) 

13. Establish correct zero-load balance ...............................................................................N.1.9., G-UR.4.2. 

Test for Mechanical Scales: 

WEAR SAFETY SHOES !

USE PROPER LIFTING TECHNIQUES ! 

1. Increasing-load test (include test loads of 500d, 2000d, and 4000d 

 as part of this test)..........................................................................................................N.1.1 

 For scales that indicate in metric units: test loads of 30, 100, 200, and 500 grams 

 For other scales: test loads of 1, 3, 7, and 15 ounces or 0.05, 0.15, 0.45, and 0.95 pounds centered, 

 Then check: 

 For scales that indicate in metric units - at each 500 grams to one quarter capacity 

 For other scales – at each pound to one-quarter capacity.

2. Shift test--one-half capacity load.....................................................................................N.1.3.1. 

3. Continue increasing-load test at three-quarters and capacity...........................................N.1.1. 

Test for Mechanical Scales (cont.):

 

4. Test for discrimination at capacity 

Shift Test Pattern

 1/2 Capacity Test Load

4

5 1 3

2

Test Weight

Position

 1/2

Capacity

Equal Arm Balance

1

4

5

2

3

Bench and Counter Scale
Retail Computing Scales

EPO No. 1 

Rev 3/02 1-11 

 (if environmental conditions permit)...............................................................................N.1.5.(1/1/86), N.1.5.1. 

 A test load equivalent to 1.4d shall cause a change in the 

 indicated or recorded value of at least 1.0d.....................................................................T.N.7.1. 

5. Decreasing-load test ......................................................................................................N.1.2. 

 For scales marked with an accuracy class 

 and having 1000 or more scale divisions, test with loads equal 

to the maximum test load at each tolerance value. For example, 

on a Class III scale, at test loads equal to 4000d, 2000d, and 

500d; for scales with n less than 1000, the test load shall be 

equal to one-half of the maximum load applied in the 

increasing-load test........................................................................................................N.1.2.1. 

 All other scales. One-half of the maximum load applied 

 in the increasing-load test ..............................................................................................N.1.2.2 

 

6. Recheck zero-load balance ............................................................................................G-UR.4.2, N.1.9. 

7. Money-value test. Check chart or drum at several points.............................................G-S.5.1. 

 The money value computation does not exceed: ...........................................................S.1.8. 

Maximum Money 

Value Interval 

Price / Kilogram Price / Pound 

$0.01 $0.55 or less $0.25 or less 

$0.02 $0.56 to $2.75 $0.26 to $1.25 

$0.05 $2.76 to $7.50 $1.26 to $3.40 

$0.10 greater than $7.50 greater than $3.40 

 

8. Establish correct zero-load balance ................................................. G-UR.4.2., N.1.9. 

 Secure all test equipment when transporting it to next location.
Medium-Capacity Scales

EPO No. 7/8 

Rev. 3/02 7/8- 1

 

Examination Procedure Outline for

Medium-Capacity Scales

It is recommended that this outline be followed for medium-capacity portable platform scales and warehouse scales, 

including self-contained and built-in types, with the following types of indicating elements: beams, dials, and electronic 

digital-indicators. Nonretroactive requirements are followed by the applicable date in parentheses. 

SAFETY NOTES 

When excerpting this Examination Procedure Outline for duplication, the "Safety Considerations" section and the 

"Glossary of Safety Key Phrases" should be duplicated and included with the outline. 

The inspector is reminded of the importance of evaluating potential safety hazards prior to an inspection and taking 

adequate precautions to avoid personal injury or damage to the device. The inspector should read and be familiar with 

the introductory section on safety found at the beginning of this publication. As a minimum, the following safety 

precautions should be noted and followed during the inspection. Definitions of each reminder are found in the "Glossary 

of Safety Key Phrases" at the back of this publication. 

Safety policies and regulations vary among jurisdictions. It is essential that inspectors or servicepersons be aware of 

all safety regulations and policies in place at the inspection site and to practice their employer’s safety policies. The 

safety reminders included in this EPO contain general guidelines useful in alerting inspectors and servicepersons to 

the importance of taking adequate precautions to avoid personal injury. These guidelines can only be effective in 

improving safety when coupled with training in hazard recognition and control. 

 Electrical Hazards Personal Protection Equipment 

 e.g., Safety Shoes, Hard Hat 

 First Aid Kit 

 Support – for Scale and Test Weights 

 Lifting 

 Transportation of Equipment 

 Location 

 also: Wet/Slick Conditions 

 Chemicals, Petroleum Products, and Hazardous Materials 

 Obstructions 
Medium-Capacity Scales

EPO No. 7/8

Rev. 3/02 7/8- 2 

Inspection: 

Safety First!!! 

Check the inspection site carefully for safety hazards and take appropriate precautions. 

Learn the nature of hazardous products used at or near the inspection site. 

Use personal protection equipment appropriate for the inspection site. 

Be sure that a first aid kit is available and that the kit is appropriate for the type of inspection activity. 

H-44 General Code 

and Scales Code 

References Comments1

1. Zero-load balance as found. 

 Digital zero indication................................................................. G-S.5.2.2.(d) (1/1/86) ME only 

 Zero indication ............................................................................ S.1.1. 

 Normal balance position.............................................................. S.1.5.1. B only 

 Adjustment of zero-load balance................................................. S.2.1.1. 

 Manual and semiautomatic zero-setting...................................... S.2.1.2. 

 Balance condition........................................................................ UR.4.1. 

2. General considerations 

 Selection of equipment ................................................................ G-UR.1.1., UR.1.1. 

 Installation 

 In accordance with manufacturers instructions....................... G-UR.2.1. 

 Indicating and recording elements.......................................... G-UR.2.2. 

 Foundation, supports, and clearance....................................... UR.2.1., UR.2.4.(1/1/73) 

Check to be sure the scale supports are adequate to support 

the scale and test weights equal to the capacity of the scale !

 Accessibility for inspection, testing, and sealing.................. G-UR.2.3. 

 Assistance in testing................................................................... G-UR.4.4. 

 Position of equipment ................................................................ G-UR.3.3. 

 Customer indications .............................................................. S.1.8.3. 

 Level indicating means .............................................................. S.2.4. 

 Level condition....................................................................... UR.4.2. 

 

1

 Key to abbreviations in Comments Column: 

 B = Beam Scales D = Dial Scales 

 E = Electronic digital scales U = Unmarked scales 

 M = Scales marked with an accuracy designation 
Medium-Capacity Scales

EPO No. 7/8

Rev. 3/02 7/8- 3 

Inspection (cont.): 

 Use 

 Facilitation of fraud..................................................................... G-S.2. 

 Method of operation.................................................................... G-UR.3.1. 

 Associated and nonassociated equipment ................................... G-UR.3.2. E only 

 Special designs or marked for special applications ..................... UR.3.5.

Environment 

 Suitable for the environment in which it is used ......................... G-UR.1.2. 

 Protection from environmental factors........................................ UR.2.3. 

Maintenance requirements............................................................... G-UR.4.1. 

 Scale modification....................................................................... UR.4.3. 

3. Marking ........................................................................................... S.6.3. 

a. Marking requirements - all devices 

 Identification ............................................................................... G-S.1. 

 Name or ID of manufacturer................................................... Retroactive 

 Model designation .................................................................. Retroactive 

 Model prefix ........................................................................... (1/1/03) 

 Nonrepetitive serial number ................................................... (1/1/68) 

 Serial number prefix ............................................................... (1/1/86) M only 

 NTEP CC prefix and number ................................................. (1/1/03) 

 (for devices that have an NTEP CC) 

 Remanufacturer information, as appropriate: 

 name and ID of remanufacturer........................................ (1/1/02) 

 model number if different from original model number ... (1/1/02) 

 Lettering...................................................................................... G-S.7. 

 Operational controls, indications, and features ........................... G-S.6. (1/1/77) 

 Visibility of identification ........................................................... G-UR.2.1.1. 

 Interchange or reversal of parts................................................... G-S.4. 

 b. Marking requirements - weighing and indicating elements in same housing or covered on the same CC 

 (in addition to marking for all devices)....................................... S.6.3. 

 Accuracy class ........................................................................ (1/1/86) M only 

 Nominal capacity .................................................................... Retroactive 

 Value of scale division with nominal 

 capacity, if not apparent .......................................................... (1/1/83) 

 Value of "e" (if different from "d")......................................... (1/1/86) 

 Temperature limits if other than 

 -10 0

C to 40 0C (14 0F to 104 0F) ............................................ (1/1/86) M only 

 Scales designed for special purposes...................................... (1/1/86) M only 

 c. Marking requirements - indicating element not permanently attached or covered on separate CC 

 (in addition to marking for all device) ........................................ S.6.3. 

 Accuracy class ........................................................................ (1/1/86) M only 

 Nominal capacity .................................................................... Retroactive 

 Value of scale division with nominal 

 capacity, if not apparent .......................................................... (1/1/83) 

 Value of "e" (if different from "d")......................................... (1/1/86) 

 Temperature limits if other than 

 -10 0

C to 40 0C (14 0F to 104 0F) ............................................ (1/1/86) M only 

 Scales designed for special purposes...................................... (1/1/86) M only 

 Maximum number of scale divisions (nmax)............................ (1/1/88) 

 

Inspection (cont.):
Medium-Capacity Scales

EPO No. 7/8

Rev. 3/02 7/8- 4 

 d. Marking requirements - weighing and load receiving element not permanently attached or covered on separate 

 CC (in addition to marking for all devices) .................................. S.6.3. 

 Accuracy class ....................................................................... (1/1/86) M only 

 Nominal capacity.................................................................... Retroactive

 Temperature limits if other than 

 -10 0

C to 40 0C (14 0F to 104 0F) ............................................ (1/1/86) M only 

 Scales designed for special purposes...................................... (1/1/86) M only 

 Maximum number of scale divisions (nmax)............................ (1/1/88) 

 Minimum verification scale division for which 

 device complies with the requirements (emin or d) .................. (1/1/88) 

 e. Marking requirements - load cell with Certificate of Conformance 

 (in addition to marking for all devices)....................................... S.6.3., S.5.4. (1/1/94) E only 

 Note: Requires information on a data plate attached 

 to the load cell or in an accompanying document. If 

 a document is provided, the serial number shall 

 appear on the load cell and in the document ............................... (1/1/88) 

 Manufacturer’s name or trademark, model 

 designation, model prefix and serial number and prefix shall 

 also be marked on both the load cell and in 

 any accompanying documents..................................................... (1/1/91) 

 Accuracy class........................................................................ (1/1/88) 

 Temperature limits if other than 

 -10 0

C to 40 0C (14 0F to 104 0F) ............................................ (1/1/86) 

 Maximum number of divisions............................................... (1/1/88) 

 “S” or “M” for single or multiple cell 

 applications............................................................................. (1/1/88) 

 Direction of loading, if not obvious........................................ (1/1/88) 

 Minimum dead load, maximum 

 capacity, safe load limit, and load cell 

 verification interval, vmin......................................................... (1/1/88) 

4. Design of weighing devices................................................................S.5. M only 

 Designation of accuracy class...................................................(1/1/86) 

 Parameters of accuracy class.....................................................(1/1/86) 

 Multi-interval/multiple-range scale division value 

5. Indicating and recording elements 

 Value of scale division ........................................................... S.1.2. (1/1/86) M only 

 Weight units ........................................................................... S.1.2.1.(1/1/89) E only 

 Values of graduated intervals or increments........................... G-S.5.3. 

 Devices that indicate or record in more than one unit ............ G-S.5.3.1. 

 Prepackaging scales only........................................................ S.1.9.1. 

 Tare 

 Value of tare division ............................................................. S.2.3. (1/1/83) 

 Tare mechanism...................................................................... S.2.3. (1/1/83) 

 Combined zero-tare (“0/T”) key ............................................. S.2.1.6. 

 Appropriateness of design 

 Indicating and recording elements.......................................... G-S.5. 

 Capacity indication, weight ranges, 

 and unit weights...................................................................... S.1.7. 

 

Inspection (cont.): 

 Appropriateness of design (cont.) 
Medium-Capacity Scales

EPO No. 7/8

Rev. 3/02 7/8- 5 

 Recommended minimum load ................................................ UR.3.1. M only 

 Maximum Load ...................................................................... UR.3.2. 

 Weighbeams .................................................................................... S.1.5. ex S.1.5.5. B&D only 

 Poises............................................................................................... S.1.6. B&D only 

 Dials and balance indicators with graduations having a specific value. 

 Graduations ............................................................................ S.1.3. B&D only 

 Indicators................................................................................ S.1.4.3., S.1.4.2. B&D only 

 Clearance ................................................................................ S.1.4.4. B&D only 

 Parallax................................................................................... S.1.4.5. B&D only 

 Damping 

 Damping means ...................................................................... S.2.5. 

 Electronic elements................................................................. S.2.5.1. (b) E only 

 Adjustable components........................................................... S.1.10. 

 Provision for sealing........................................................................ S.1.11. (a) (1/1/79) 

 S.1.11. (b) (1/1/90) E only 

 S.1.11. (c) (1/1/95), G.S.8. E only 

 Security seal..................................................................................... G-UR.4.5.

 

6. Weighing elements 

 Antifriction means....................................................................... S.4.1. 

 Adjustable components ............................................................... S.4.2. 

 Multiple load-receiving elements................................................ S.4.3. 

 Drainage, if wet commodities are weighed ................................. S.3.2., UR.3.6. 

 

Pretest Determinations: 

1. Tolerances. 

 Acceptance/maintenance ................................................................. G-T.1., G-T.2. 

 Application ...................................................................................... G-T.3. 

 Principles......................................................................................... T.N.1. M only 

 Tolerance values: 

Determine number of scale Scale capacity 

divisions (n)2 ........................................................................ n = Value of scale division 

If scale is marked with an accuracy designation or for unmarked 

scales with 5000 or fewer scale divisions. 

 Tolerance application – unmarked......................................... T.1.1. U only 

Tolerance application - marked .............................................. T.N.2.1. M only 

Subsequent verification examinations .................................... T.N.2.3. M only 

Multirange scales.................................................................... T.N.2.4. M only 

Pretest Determinations (cont.):

 Tolerance Values (cont.) 

Ratio tests............................................................................... T.N.2.5. MB only 

Maintenance tolerance values................................................. T.N.3.1./Table 6 (Class III) 

Acceptance tolerance values................................................... T.N.3.2. 

 

2 On a multiple range or multi-interval scale the number of divisions for each range independently shall not exceed the 

maximum specified for the accuracy class. The number of scale divisions, n, for each weighing range is determined by 

dividing the scale capacity for each range by the verification scale division, e, for each range (i.e., do not add "n" for the

ranges together). On a scale system with multiple load receiving elements and multiple indications each element 

considered shall not independently exceed the maximum specified for the accuracy class. If the system has a summing 

indicator, the nmax for the summed element shall not exceed the maximum specified for the accuracy class. (Table 3 

footnote added 1998). 
Medium-Capacity Scales

EPO No. 7/8

Rev. 3/02 7/8- 6 

Multiple indicating/recording elements .................................. T.N.4.1. M only 

Single indicating/recording elements...................................... T.N.4.2 M only 

Single indicating element/multiple indications....................... T.N.4.3 M only 

Shift or section test ................................................................. T.N.4.4. M only 

Repeatability........................................................................... T.N.5. M only 

2. Sensitivity. 

 Application.................................................................................. T.2.1. UB only 

 General........................................................................................ T.2.2. UB only 

 Sensitivity requirement, equilibrium change............................... T.3.1. UB only 

 Sensitivity ................................................................................... T.N.6. MB only 

3. Discrimination. 

Analog automatic indicating (includes balance indicators 

with graduations having specific values)......................................... T.N.7.1. MD only 

Digital automatic indicating............................................................. T.N.7.2. ME only 

4. Minimum test weights and test loads............................................... N.3. 

Test Notes: 

1. Error weights. Balance small error weights on the platform, the 

smallest weight being equal to the minimum tolerance value at maximum test load. 

2. Check repeatability and agreement between indicatons 

throughout the test. 

 Repeatability of indications......................................................... G-S.5.4. 

 Digital indication and representation .......................................... G-S.5.2.2. 

3. Recheck zero-load balance each time test load is removed. 

 Zero-load balance change ........................................................... N.1.9. 

 Abnormal performance ............................................................... G-UR.4.2. 

4. If scale is equipped with a ticket printer or 

type-recording beam, print ticket at each test 

load. Check effectiveness of motion detection. 

 Digital indication and representation .......................................... G-S.5.2.2. 

 Recorded representations............................................................ G-S.5.6. 

 Money value, mathematical agreement....................................... G-S.5.5. 

 Motion detection ......................................................................... S.2.5.1.(b) E only 

 Value of the indicated and recorded 

 scale division............................................................................... UR.1.3.(1/1/86) M only 

5. If, during the conduct of the test, the performance 

of the device is questionable with respect to the 

zone of uncertainty or the width of zero, 

Test Notes (cont.):

adequate tests should be conducted to determine 

 compliance; however, they must be conducted under 

 controlled conditions. 

 Digital indicating elements.......................................................... S.1.1.1.(1/1/93) E only 

 Discrimination test ...................................................................... N.1.5. MD/E only 

 Digital device .............................................................................. N.1.5.1. ME only 
Medium-Capacity Scales

EPO No. 7/8

Rev. 3/02 7/8- 7 

6. If the device is equipped with operational features 

such as programmable tare, multiple tare memory, 

weigh-in/weigh-out, or multiple weighing elements, 

check proper operation and appropriateness. E only 

 Maintenance of equipment.......................................................... G-UR.4.1. 

 Abnormal performance ............................................................... G-UR.4.2. 

 Multiple load-receiving elements................................................ S.4.3. 

 Manual gross weight entry .......................................................... S.1.12.(1/1/93), UR.3.9. 

Test: 

WEAR SAFETY SHOES !

USE PROPER LIFTING TECHNIQUES !

1. Sensitivity test at zero load............................................................... N.1.4. B only 

2. Discrimination test at zero load, if applicable .................................. N.1.5.(1/1/86) MD/E 

 Digital Device................................................................................... N.1.5.1. E only 

 

3. Increasing-load test (with the load centered) ................................... N.1.1. 

 Initial verification – to capacity ....................................................... N.3. 

 Subsequent verification 

a. Small Scales - at minimum load (20d), 500d, 2000d, 

 4000d to capacity 

b. Larger scales – at minimum load (20d), 500d, 2000d, 

 4000d to capacity or, at tolerance intervals to table 

 4 values. 

c. Beam scales - at a minimum, test at half 

 and full capacity on weighbeam. Scales not equipped 

 with a full capacity beam should be ratio tested using 

 standard weights on counterpoise hanger. At each test 

 load, test scale counterpoise weights by substituting them 

 for standard weights. If there is a noticeable change in 

 indication, remove the counterpoise weight from service 

 until it can be determined that it meets the requirements 

 in the Weight Code of NIST Handbook 44................................. N.1.7. B only 

Test (cont.):

4. Shift test Use quarter-capacity test load centered 

successively over each main load support or 

half-capacity load centered successfully at the 

center of each quarter of the load-receiving element 

(can be conducted during increasing-load test)................................ N.1.3.8. 

5. Sensitivity test at maximum test load .............................................. N.1.4. B only 

 Discrimination test at maximum test load........................................ N.1.5. MD&E only 
Medium-Capacity Scales

EPO No. 7/8

Rev. 3/02 7/8- 8 

 (if applicable) 

6. RFI/EMI tests (if a problem is suspected) 

 Radio Frequency Interference (RFI) 

Electromagnetic Interference (EMI) 

 Testing with nonassociated equipment........................................ G-N.2. E only 

 Environment................................................................................ G-UR.1.2. 

 Associated and nonassociated equipment ................................... G-UR.3.2. E only 

 Abnormal performance ............................................................... G-UR.4.2. E only 

 Presence of RFI verified.............................................................. N.1.6. 

 Tolerance 

 Unmarked scales..................................................................... T.4. U only 

 Marked Scales ........................................................................ T.N.9. M only

7. Test for over-capacity indication. .................................................... S.1.7. 

8. Decreasing-load test......................................................................... N.1.2. D & E only 

 Scales marked I, II, III, or IIII..................................................... N.1.2.1. M only 

 Tests shall be conducted with test loads equal to the 

 maximum test load at each tolerance value. For 

 example, on a Class III scale, at test loads equal 

 to 4000d, 2000d, and 500d; for scales with n less 

 than 1000, the test load shall be equal to one-half of 

 the maximum load applied in the increasing-load test. 

 All other scales............................................................................ N.1.2.2. 

 The test load shall be equal to one-half of 

 the maximum load applied in the increasing-load test. 

9. Recheck zero-load balance................................................N.1.9., G-UR.4.2. 

10. Substitution or strain load test .......................................................... Table 4. 

 The scale shall be tested from zero to at least 12.5 percent of 

 scale capacity using known test weights and then to at 

 least 25 percent of scale capacity using either a substitution or 

 strain load test that utilizes known test weights of at least 

 12.5 percent of scale capacity. Not more than three substitutions 

 shall be used during substitution testing. Whenever practical, 

 a strain load test should be conducted to the used capacity of 

 the scale. Tolerance applies only to the known test load. 

11. Recheck zero-load balance................................................ N.1.9., G-UR.4.2. 

 

Test (cont.):

12. Conduct out-of-level test (portable scales 

without level-indicating means only)............................................... S.2.4. 

13. Test for proper design of automatic zerosetting mechanism, if scale is so equipped. ..................................... S.2.1.3.(c) (1/1/81) E only 

Under normal operating conditions the maximum load that can 

be “rezeroed” when placed on or removed from the platform 

all at once, shall be 1.0 scale division. 
Medium-Capacity Scales

EPO No. 7/8

Rev. 3/02 7/8- 9 

14. Check proper design of tare auto-clear, 

if scale is so equipped...................................................................... S.2.3. (1/1/83) E only 

15. If scale is equipped with a semi-automatic 

zero-setting mechanism, test effectiveness. ..................................... S.2.1.2. E only 

of motion detection 

16. Establish correct zero-load balance...................................... N.1.9., G-UR.4.2. 

After all equipment at a location has been tested, review 

results to determine compliance with equipment 

maintenance and use of adjustments................................................ G-UR.4.1., G-UR.4.3. 
Mechanical Meat Beams and Monorail Scales

EPO No. 9 

Rev. 3/02 9- 1

 

Examination Procedure Outline for 

Mechanical Meat Beams and Monorail Scales

It is recommended that this outline be followed for meat beams and monorail scales equipped with weigh-beams or 

mechanical dials. Requirements that apply only to scales marked with an accuracy class are indicated with an asterisk. 

Nonretroactive requirements are followed by the applicable date in parentheses. 

SAFETY NOTES 

When excerpting this Examination Procedure Outline for duplication, the "Safety Considerations" section 

and the "Glossary of Safety Key Phrases" should be duplicated and included with the outline. 

The inspector is reminded of the importance of evaluating potential safety hazards prior to an inspection 

and taking adequate precautions to avoid personal injury or damage to the device. The inspector should read and 

be familiar with the introductory section on safety found at the beginning of this publication. As a minimum, the 

following safety precautions should be noted and followed during the inspection. Definitions of each reminder 

are found in the "Glossary of Safety Key Phrases" at the back of this publication. 

Safety policies and regulations vary among jurisdictions. It is essential that inspectors or servicepersons be 

aware of all safety regulations and policies in place at the inspection site and to practice their employer’s 

safety policies. The safety reminders included in this EPO contain general guidelines useful in alerting 

inspectors and servicepersons to the importance of taking adequate precautions to avoid personal injury. 

These guidelines can only be effective in improving safety when coupled with training in hazard recognition 

and control.

 Clothing Personal Protection Equipment 

 e.g., Safety Shoes 

 First Aid Kit Hardhat – for protection from overhead hazards 

 (e.g., meat hooks) 

 Lifting Eye Protection – for protection from hanging 

 meat hooks

 Location 

 also: Wet/Slick Conditions Support – for scales, test weights, and meat hooks, or

 Overhead Hazards test platform

 Obstructions 

 Transportation of Equipment 
Mechanical Meat Beams and Monorail Scales

EPO No. 9 

Rev. 3/02 9- 2

 

Inspection:

H-44 General Code and 

Scales Code References 

1. Zero-load balance as found .............................................................................................S.1.1., S.2.1.1., S.2.1.2., 

 UR.4.1. 

If the device is not in balance, the user should be made aware of paragraph UR.4.1., 

and a warning issued if necessary. If device is set for tare, check accuracy of the tare 

being taken. 

2. Indicating and recording elements. 

 Scale division, value (d) and number (n) .......................................................................S.1.2.*, G-UR.1.1., UR.1., 

UR.1.1.(b), G-S.5.3. 

 Tare division value..........................................................................................................S.2.3.(1/1/83) 

 Tare mechanism..............................................................................................................S.2.3. 

 Weighbeams ...................................................................................................................S.1.5. except S.1.5.5. 

 Poises ..............................................................................................................................S.1.6. 

 Dials and balance indicators ...........................................................................................S.1.3., S.1.4., S.2.2. 

Appropriateness......................................................................................................G-S.5., S.1.7., 

UR.1.1.(a)*, 

UR.3.1.*, S.5.*, UR.3.2. 

Damping means......................................................................................................S.2.5. 

Customer readability, if applicable.........................................................................G-UR.3.3. 

Adjustable components ..........................................................................................S.1.10. 

3. Marking ...........................................................................................................................S.6.3., S.6.2 

 a. Marking requirements - all devices 

 Identification ............................................................................................................G-S.1. 

 Name or ID of manufacturer...............................................................................Retroactive 

 Model designation...............................................................................................Retroactive 

 Model prefix. ......................................................................................................(1/1/03) 

 Nonrepetitive serial number................................................................................(1/1/68) 

 

Inspection (cont.): 

 Check the inspection site carefully for 

 safety hazards and take appropriate precautions. 

 Use caution in moving in wet, slippery areas.

 Use personal protection equipment appropriate for the inspection site. 

 Be sure that a first aid kit is available and that the 

 kit is appropriate for the type of inspection activity.
Mechanical Meat Beams and Monorail Scales

EPO No. 9 

Rev. 3/02 9- 3

 Marking requirements - all devices (cont.) 

 Identification ............................................................................................................G-S.1. 

 Serial number prefix ...........................................................................................(1/1/86) 

 NTEP CC prefix and number..............................................................................(1/1/03) 

 (for devices that have an NTEP CC) 

 Remanufacturer information, as appropriate: 

 name and ID of remanufacturer .....................................................................(1/1/02) 

 model number if different from original model number ................................(1/1/02) 

 Lettering...................................................................................................................G-S.7. 

 Operational controls, indications, and features ........................................................G-S.6. (1/1/77) 

 Visibility of identification ........................................................................................G-UR.2.1.1. 

 Interchange or reversal of parts................................................................................G-S.4. 

 b. Marking requirements - weighing and indicating elements in same housing or covered on the same CC 

 (in addition to marking for all devices) ..................................................................S.6.3. 

 Accuracy class........................................................................................................(1/1/86) 

 Nominal capacity....................................................................................................Retroactive 

 Value of scale division with nominal 

 capacity, if not apparent .........................................................................................(1/1/83) 

 Value of "e" (if different from "d") ........................................................................(1/1/86) 

 Temperature limits if other than 

 -10 0

C to 40 0C (14 0F to 104 0F)............................................................................(1/1/86) 

 Scales designed for special purposes......................................................................(1/1/86) 

 c. Marking requirements - indicating element not permanently attached or covered on separate CC 

 (in addition to marking for all device)....................................................................S.6.3. 

 Accuracy class........................................................................................................(1/1/86) 

 Nominal capacity....................................................................................................Retroactive 

 Value of scale division with nominal 

 capacity, if not apparent .........................................................................................(1/1/83) 

 Value of "e" (if different from "d") ........................................................................(1/1/86) 

 Temperature limits if other than 

 -10 0C to 40 0

C (14 0F to 104 0F) ............................................................................(1/1/86) 

 Scales designed for special purposes......................................................................(1/1/86) 

 Maximum number of scale divisions (nmax)............................................................(1/1/88) 

 d. Marking requirements - weighing and load receiving element not permanently attached or covered on separate 

 CC (in addition to marking for all devices) ..............................................................S.6.3. 

 Accuracy class........................................................................................................(1/1/86) 

 Nominal capacity....................................................................................................Retroactive 

 Temperature limits if other than 

 -10 0C to 40 0

C (14 0F to 104 0F) ............................................................................(1/1/86) 

 Scales designed for special purposes......................................................................(1/1/86) 

 Maximum number of scale divisions (nmax)............................................................(1/1/88) 

 Minimum verification scale division for which 

 device complies with the requirements (emin or d)..................................................(1/1/88) 

 

4. Installation ......................................................................................................................UR.2.3., UR.2.4., G-UR.2. 

Inspection (cont.): 
Mechanical Meat Beams and Monorail Scales

EPO No. 9 

Rev. 3/02 9- 4

5. Design of balance, tare, level, damping, and arresting mechanisms ...............................S.2.1.4, S.2.1.5, S.2.1.6 

6. Design of weighing elements..........................................................................................S.4 

7. Maintenance, use, and environmental factors (cleanliness, obstructions, 

 modifications, etc.)..........................................................................................................G-S.2., G-UR.1.2., GUR.3.1., G-UR.4., UR.4.3. 

8. Assistance .......................................................................................................................G-UR.4.4. 

Pretest Determinations:

1. Tolerances. 

 Acceptance/maintenance.................................................................................................G-T.1., G-T.2. 

 Application......................................................................................................................T.N.2.1., T.N.2.3., 

T.N.2.5. 

 Tolerance values: 

 Scales marked with an accuracy class............................................................T.N.3.1. Table 6 (Class 

III), T.N.3.2., T.N.4., 

T.N.5. 

 Scales not marked ..........................................................................................T.1.1., T.N.3.1. Table 6 

(Class III), T.N..3.2., 

T.N.4.1., T.N.4.2., 

T.N.4.3., T.N.5. 

 Discrimination........................................................................................................T.N.7.1.* 

 Sensitivity: 

 Scales marked ................................................................................................T.N.6.1.(b), T.N.6.2. 

 Scales not marked ..........................................................................................T.2.1., T.2.2., T.3. 

2. Select trolleys, trees, chains, or other auxiliary gear necessary to suspend test weights 

 on rail or meat hook. If two or more trolley-and-tree combinations are used, they should 

 be uniform in weight within ± 57 grams (± 2 ounces). 

Check to be sure the scale supports are adequate to support 

the scale, test weights equal to the capacity of the scale, 

and test platforms or chains used to suspend test weights!
Mechanical Meat Beams and Monorail Scales

EPO No. 9 

Rev. 3/02 9- 5

Pretest Determinations (cont.):

 

3. Minimum test weights and test load................................................................................N.3. 

Test Notes:

1. Suspend auxiliary gear (trolleys, trees, chains) from live rail or hook as required. 

2. If beam scale, place small error weights on or suspend from the live rail or hook. The 

 Value of the smallest weight should be equal to the minimum tolerance value and the 

 total of all the weights should be equal to the tolerance at maximum test load. 

3. Balance in auxiliary gear and error weights. 

 

4. Check repeatability of and agreement between indications throughout test....................G-S.5.2.2.(b), T.N.5. 

5. Recheck zero-load balance each time test load is removed.............................................N.1.9., G-UR.4.2. 

6. If scale is equipped with a type-recording beam or printer, print a ticket at each 

 test load...........................................................................................................................G-S.5.6. 

Test: 

 

1. Sensitivity test at zero-load (weighbeams only) ............................................................N.1.4. 

 Discrimination at zero load (dials only).........................................................................N.1.5. 

2. Increasing-load test........................................................................................................N.1.1. 

 a. Beam scales. Test at not less than three graduations or notches on weigh-beam. 

 Scales not equipped with a full capacity beam should be ratio tested 

using standard weights on counterpoise hanger. When ratio testing, test poise 

and beam by substituting poise position with the removal of standard weights 

from counterpoise hanger. ......................................................................................N.1.7. 

 b. Dial scales. Test at not less than three points on reading face, including 

all possible quarters of capacity. Test all unit weights possible. If equipped 

with tare bars, test at one-half and full capacity of each bar. 

Test (cont.):

Wear appropriate personal protection equipment such as 

hard hats and eye protection to prevent injury from 

overhead meat hooks and hanging carcasses. 

Wear safety shoes to prevent possible injury from 

falling weights and slipping on slick surfaces. 

WEAR SAFETY SHOES!

USE PROPER LIFTING TECHNIQUES !
Mechanical Meat Beams and Monorail Scales

EPO No. 9 

Rev. 3/02 9- 6

3. Shift test. Use test load equal to the largest load that can be anticipated, but never less 

 than one-half capacity. Apply load successively on the right end, the left end and the 

 center of the live rail. This can be conducted during the increasing-load test ..............N.1.3.6. 

4. Beams and balance indicators only, SR at maximum test load......................................N.1.4. 

 Dials only, discrimination at maximum test load. .........................................................N.1.5. 

5. Dials only. Decreasing-load test at one-half of maximum test load (at no 

 less than one-half dial face capacity).............................................................................N.1.2.1.*, N.1.2.2. 

6. Beams only. Counterpoise weight test (see EPO for Weights). 

7. Remove all test weights and determine any zero-load balance change .........................N.1.9., G-UR.4.2. 

8. Remove error weights and/or auxiliary gear and establish correct zero-load balance. 
Monorail Scales Equipped with Electronic Digital Indicators

EPO No. 9E 

Rev. 3/02 9E- 1

 

Examination Procedure Outline for 

Monorail Scales Equipped with 

 Electronic Digital Indicators

It is recommended that this outline be followed for monorail scales equipped with electronic digital indicators used to 

weigh statically or dynamically. Requirements that apply only to scales marked with an accuracy class are indicated with 

an asterisk. Nonretroactive requirements are followed by the applicable date in parentheses. 

SAFETY NOTES 

When excerpting this Examination Procedure Outline for duplication, the "Safety Considerations" section and the 

"Glossary of Safety Key Phrases" should be duplicated and included with the outline. 

The inspector is reminded of the importance of evaluating potential safety hazards prior to an inspection and taking 

adequate precautions to avoid personal injury or damage to the device. The inspector should read and be familiar with 

the introductory section on safety found at the beginning of this publication. As a minimum, the following safety 

precautions should be noted and followed during the inspection. Definitions of each reminder are found in the 

"Glossary of Safety Key Phrases" at the back of this publication. 

Safety policies and regulations vary among jurisdictions. It is essential that inspectors or servicepersons be aware 

of all safety regulations and policies in place at the inspection site and to practice their employer’s safety policies. 

The safety reminders included in this EPO contain general guidelines useful in alerting inspectors and 

servicepersons to the importance of taking adequate precautions to avoid personal injury. These guidelines can 

only be effective in improving safety when coupled with training in hazard recognition and control.

 Clothing Personal Protection Equipment 

 e.g., Safety Shoes 

 First Aid Kit Hardhat – for protection from overhead hazards 

 (e.g., meat hooks) 

 Lifting 

 Eye Protection – for protection from hanging 

 Location meat hooks 

 

 also: Wet/Slick Conditions Support – for scales, test weights, and meat hooks, or 

 Overhead Hazards test platform 

 Obstructions 

 Transportation of Equipment 
Monorail Scales Equipped with Electronic Digital Indicators

EPO No. 9E 

Rev. 3/02 9E- 2

 

Inspection:

Safety First !!! 

 

H-44 General Code and

Scales Code References 

1. Zero-load balance as found. If the device 

 is not in balance, the user should be made 

 aware of paragraph UR.4.1., and a warning 

 issued if necessary. If device is set for 

 tare, check accuracy of the tare being taken. .................................................................S.1.1., S.1.1.1., S.2.1.1., 

S.2.1.2., S.2.1.4., UR.4.1., 

G-S.5.2.2(d)* 

2. Indicating and recording elements. 

 Scale division, value (d) and number (n) ...............................................................S.1.2.*, S.1.2.1. (1/1/89), 

S.1.2.2. S.5.*, G-UR.1.1., 

UR.1.1., UR.1.1.(b), 

G-S.5.3., UR 1.3.1(a), 

UR.3.10. 

 Tare division value .................................................................................................S.2.3. (1/1/83), S.2.3.1. 

 Tare mechanism .....................................................................................................S.2.3. 

 Appropriateness......................................................................................................G-S.5., S.1.7., S.5.2.*, 

UR.1.1.(a)*, UR.3.1.* 

 Customer readability, if applicable.........................................................................G.UR.3.3. 

 Damping means......................................................................................................S.2.5., S.2.5.1. 

 Adjustable components ..........................................................................................S.1.10. 

 Provision for sealing...............................................................................................S.1.11. (1/1/90), 

G-UR. 4.5., G.S.8. 

Inspection (cont.):

Check the inspection site carefully for 

 safety hazards and take appropriate precautions. 

 Use caution in moving in wet, slippery areas. 

 Use personal protection equipment appropriate for the inspection site. 

 Be sure that a first aid kit is available and that the 

 kit is appropriate for the type of inspection activity. 
Monorail Scales Equipped with Electronic Digital Indicators

EPO No. 9E 

Rev. 3/02 9E- 3

3. Marking .........................................................................................................................S.6.3., S.6.2. 

 a. Marking requirements - all devices 

 Identification ..........................................................................................................G-S.1. 

 Name or ID of manufacturer................................................................................Retroactive 

 Model designation ...............................................................................................Retroactive 

 Model prefix ........................................................................................................(1/1/03)

 Nonrepetitive serial number ................................................................................(1/1/68) 

 Serial number prefix ............................................................................................(1/1/86) 

 NTEP CC prefix and number 

 (for devices that have an NTEP CC) ..................................................................(1/1/03) 

 Remanufacturer information, as appropriate: 

 name and ID of remanufacturer.........................................................................(1/1/02) 

 model number if different from original model number....................................(1/1/02) 

 Lettering .................................................................................................................G-S.7. 

 Operational controls, indications, and features.......................................................G-S.6. (1/1/77) 

 Visibility of identification ......................................................................................G-UR.2.1.1.

 Interchange or reversal of parts ..............................................................................G-S.4. 

 b. Marking requirements - weighing and indicating elements in same housing or covered on the same CC 

 (in addition to marking for all devices) ..................................................................S.6.3. 

 Accuracy class.....................................................................................................(1/1/86) 

 Nominal capacity.................................................................................................Retroactive

 Value of scale division with nominal capacity, if not apparent ...........................(1/1/83) 

 Value of "e" (if different from "d")......................................................................(1/1/86) 

 Temperature limits if other than -10 0

C to 40 0C (14 0F to 104 0F)......................(1/1/86) 

 Scales designed for special purposes...................................................................(1/1/86) 

 c. Marking requirements - indicating element not permanently attached or covered on separate CC 

 (in addition to marking for all device)....................................................................S.6.3. 

 Accuracy class.....................................................................................................(1/1/86) 

 Nominal capacity.................................................................................................Retroactive

 Value of scale division with nominal capacity, if not apparent ...........................(1/1/83) 

 Value of "e" (if different from "d")......................................................................(1/1/86) 

 Temperature limits if other than –10 0

C to 40 0C (14 0F to 104 0F) .....................(1/1/86) 

 Scales designed for special purposes...................................................................(1/1/86) 

 Maximum number of scale divisions (nmax).........................................................(1/1/88) 

 d. Marking requirements - weighing and load receiving element not permanently attached or covered on separate 

 CC (in addition to marking for all devices) ..............................................................S.6.3. 

 Accuracy class.....................................................................................................(1/1/86) 

 Nominal capacity.................................................................................................Retroactive

 Temperature limits if other than –10 0

C to 40 0C (14 0F to 104 0F) .....................(1/1/86) 

 Scales designed for special purposes...................................................................(1/1/86) 

 Maximum number of scale divisions (nmax).........................................................(1/1/88) 

 Minimum verification scale division for which 

 device complies with the requirements (emin or d) ...............................................(1/1/88) 

Inspection (cont.):

 e. Marking requirements - load cell with Certificate of Conformance .......................S.6.3., S.5.4. (1/1/94) 

 (in addition to marking for all devices) 
Monorail Scales Equipped with Electronic Digital Indicators

EPO No. 9E 

Rev. 3/02 9E- 4

 Note: Requires information on a data plate attached to the load cell or in 

 accompanying document. If a document is provided, the serial number shall 

 appear on the load cell and in the document...........................................................(1/1/88) 

 Manufacturer’s name or trademark, model designation, model prefix, and serial 

 number and prefix shall also be marked on both the load cell and in 

 any accompanying documents................................................................................(1/1/91) 

 Accuracy class.....................................................................................................(1/1/88) 

 Temperature limits if other than –10 0

C to 40 0C (14 0F to 104 0F) .....................(1/1/86) 

 Maximum number of divisions............................................................................(1/1/88) 

 “S” or “M” for single or multiple cell applications..............................................(1/1/88) 

 Direction of loading, if not obvious.....................................................................(1/1/88) 

 Minimum dead load, maximum capacity, safe load limit, and load cell 

 verification interval, vmin......................................................................................(1/1/88) 

4. Design of weighing elements.........................................................................................S.4. 

5. Installation ....................................................................................................................UR.2.3., UR.2.4., G-UR.2. 

 

6. Maintenance, use, and environmental factors (cleanliness, obstructions, 

 modifications, etc.) ........................................................................................................G-S.2., G-UR.1.2., 

G-UR.3.1., G-UR.3.2., 

G-UR.4., UR.4.3. 

7. Assistance......................................................................................................................G-UR.4.4. 

 

8. Provisions for testing and accessability .........................................................................UR.2.9., G-UR.2.3. 

9. Determination of Load Cell Suitability (applicable to load cells with an NTEP Certificate of Conformance): 

a. The number of scale divisions (n) of the scale is less than or equal to the nmax

 of the indicator or the load cells, whichever is less; e.g., if the indicator has an nmax of 10,000 

 and the load cells have an nmax of 5,000, then the scale may use up to 5,000 divisions. 

 b. The load cell is approved for the required accuracy class. Note: A Class II load cell 

 may be used in a Class III application; however the opposite is not true. 

c. The load cell is rated Single (S) or Multiple (M) use as appropriate to the application. 

 Note: A load cell rated for single use may be used in a single or multiple load cell 

 application; however, a load cell rated for multiple use cannot be used in a single 

 load cell application. 

Inspection (cont.):

 d. The load cell complies with the requirements for temperature effect 

 on zero-load balance.........................................................................................S.5.4., T.N.8.1.3. 

Check to be sure the scale supports are adequate to support 

the scale, test weights equal to the capacity of the scale 

and test platforms or chains used to suspend test weights !
Monorail Scales Equipped with Electronic Digital Indicators

EPO No. 9E 

Rev. 3/02 9E- 5

Note: Testing to determine the effect of temperature on zero-load balance cannot be performed in the 

field; however, for purposes of field inspection, a load cell is considered to comply with T.N.8.1.3. 

if the vmin value marked on the load cell is less than or equal to the vmin value as calculated below based 

upon the “d” and “N” for the scale; if it is not, the scale does not comply with T.N.8.1.3. 

Full electronic scale with more than one load cell: The verification scale division vmin, for the load 

cells must be less than or equal to the scale division, “d,” divided by the square root of the 

number of load cells, N, used in the scale: 

 vmin ≤ d 

 /N 

For Example: 

A monorail scale with two load cells and a displayed scale division of 1 lb, the maximum value permitted for each load 

cell is 0.71 lb. The calculation is shown below. If the value marked on the load cell is less than or equal to the value 

computed for the vmin, then the load cell is considered to comply with T.N.8.1.3. 

vmin ≤ d = 1 lb = 1 lb = 0.71 lb 

 /N /2 1.414 

For scales with mechanical lever systems:

 vmin ≤ d 

 /N x scale multiple 

Pretest Determinations:

1. Tolerances. 

 Acceptance/Maintenance........................................................................................G-T.1., G-T.2. 

 Application ...................................................................................................................T.N.2.1., T.N.2.3., 

T.N.2.4. 

 Tolerance values: 

 Scales marked with an accuracy.............................................................................T.N.3.1. Table 6 

 (Class III), T.N.3.2., 

T.N.3.8., T.N.4.1., 

T.N.4.4., T.N.4.5., T.N.5. 

 Scales not marked...................................................................................................T.1.1.,T.N.3.1. Table 6 

 (Class III), T.N.3.2., 

T.N.3.8., T.N.4.1., T.N.5. 

 Discrimination .......................................................................................................T.N.7.2. 

Pretest Determinations:

2. Select trolleys, trees, chains, or other auxiliary gear necessary to suspend test weights on rail or 

 meat hook. If two or more trolley-and-tree combinations are used, they should be uniform in 

 weight (within plus or minus two ounces). 

Wear appropriate personal protection equipment such as 

hard hats and eye protection to prevent injury from 

overhead meat hooks and hanging carcasses 

 falling weights and slipping on slick surfaces. 
Monorail Scales Equipped with Electronic Digital Indicators

EPO No. 9E 

Rev. 3/02 9E- 6

 

3. Minimum test weights and test loads.............................................................................N.3. 

Test Notes:

1. Suspend auxiliary gear (trolleys, trees, chains) from live rail. 

2. Balance in auxiliary gear. 

3. Check repeatability and agreement between indications throughout test. .....................T.N.5., G-S.5.2.2.(a) 

4. Check zero-load balance each time test load is removed...............................................N.1.9., G-UR.4.2. 

5. If the scale is equipped with a printer, print a ticket at each test load; check 

 effectiveness of motion detection. .................................................................................G-S.5.6., S.2.5.1., 

 UR.1.3.(1/1/86) 

6. If, during the conduct of the test, the performance of the device is questionable 

 with respect to the zone of uncertainty or the width of zero, adequate tests should 

 be conducted to determine compliance..........................................................................N.1.5., N.1.5.1., S.1.1.1. 

7. If the device is equipped with operational features such as automatic zero-setting 

 mechanism, programmable tare,*manual weight entries, or two scales 

 with one printer, check proper operation and appropriateness. 

 

 *Note: See UR.3.9. The use of manual gross weight entries, are not allowed on monorail scales. 
Monorail Scales Equipped with Electronic Digital Indicators

EPO No. 9E 

Rev. 3/02 9E- 7

Static Test: 

1. Increasing-load test. Test at not less than three points to maximum capacity 

 test load. ........................................................................................................................N.1.1. 

2. Shift test. Use test load equal to the largest load that can be anticipated to be 

 weighed at the installation, but never less than one-half capacity. Apply load 

 successively on the right end, the left end, and the center of the live rail. This can be 

 conducted during the increasing-load test......................................................................N.1.3.6. 

 

3. RFI/EMI test (if a problem is suspected).......................................................................G-N.2., G-UR.3.2., 

G-UR.4.2., G-UR.1.2., 

N.1.6., T.4., T.N.9.* 

 Radio Frequency Interference (RFI) 

Electromagnetic Interference (EMI) 

4. Over-capacity test, if deemed necessary........................................................................S.1.7., S.2.1.5. 

5. Decreasing-load test. Test at one-half of maximum test load. ......................................N.1.2. 

6. Remove all test weights and determine any zero-load balance change. ........................N.1.9., G-UR.4.2. 

7. Test for proper design of automatic zero-setting mechanism, if device is 

 so equipped....................................................................................................................S.2.1.3.(c) (1/1/81) 

8. If device is equipped with a semi-automatic zero-setting mechanism (push button), test 

 effectiveness of motion detection. .................................................................................S.2.1.2.(b)

9. Establish correct zero-load balance. 

Dynamic test ...................................................................................................................N.1.3.6.1. 

On a dynamic test with 20 or more test drafts, 10 percent of the individual test drafts may be two times the basic 

tolerances, providing the error on the total of all test load drafts does not exceed 0.2 percent. 

1. Conduct dynamic test w/livestock carcasses 

2. Test no less than 20 test loads using carcasses or portions of carcasses of the type normally weighed. 

 (two additional test loads may be included in the test run in the event that one or two of the test load 

 are rendered unusable. 

WEAR SAFETY SHOES !

USE PROPER LIFTING TECHNIQUES ! 
Monorail Scales Equipped with Electronic Digital Indicators

EPO No. 9E 

Rev. 3/02 9E- 8

Dynamic test (cont.).....................................................................................................N.1.3.6.1. 

3. Position the test carcasses far enough ahead of the scale so the swaying motion settles to duplicate the normal 

sway of a continuously running plant chain. 

4. If the plant conveyor chain does not space or prevent the carcasses from touching one another, the dynamic test 

should not be conducted until this condition is corrected. 

5. Individually weigh (statistically) the carcasses on the same scale being tested or another monorail scale in close 

proximity with the same or smaller divisions. 

a) The scale selected for weighing the carcasses must be tested statically with test weights. 

6. If the scale being tested is used for weighing freshly slaughtered animals, a static weighment of the carcasses 

 must be taken as quickly as possible before or following the Dynamic weighment to avoid loss due to shrinkage. 

7. If multiple dynamic tests are conducted using the same carcasses, obtain static weights before and after 

 multiple dynamic tests. 

8. If the carcass changes weight between static tests, the amount of weight change should be taken into account, 

 or the carcass should be discarded for tolerance purposes. 
Livestock/Animal Scales Mechanical Analog Indicating 

EPO No. 12 

Rev. 3/02 12-1 

 

Examination Procedure Outline for

Livestock and Animal Scales 

Mechanical – Analog Indicating 

It is recommended that this outline be followed for livestock and animal scales equipped with weighbeams or dials. 

Requirements that apply only to scales marked with an accuracy class are indicated with an asterisk. Nonretroactive 

requirements are followed by the applicable date in parentheses. 

SAFETY NOTES 

When excerpting this Examination Procedure Outline for duplication, the "Safety Considerations" section and the 

"Glossary of Safety Key Phrases" should be duplicated and included with the outline. 

The inspector is reminded of the importance of evaluating potential safety hazards prior to an inspection and taking 

adequate precautions to avoid personal injury or damage to the device. The inspector should read and be familiar with 

the introductory section on safety found at the beginning of this publication. As a minimum, the following safety 

precautions should be noted and followed during the inspection. Definitions of each reminder are found in the "Glossary 

of Safety Key Phrases" at the back of this publication. 

Safety policies and regulations vary among jurisdictions. It is essential that inspectors or servicepersons be aware of 

all safety regulations and policies in place at the inspection site and to practice their employer’s safety policies. The 

safety reminders included in this EPO contain general guidelines useful in alerting inspectors and servicepersons to 

the importance of taking adequate precautions to avoid personal injury. These guidelines can only be effective in 

improving safety when coupled with training in hazard recognition and control. 

 Clothing Personal Protection Equipment 

 e.g., Safety Shoes 

 Electrical Hazards Hard Hat 

 

 

 First Aid Kit Safety Cones/Warning Signs 

 

 Lifting Support – for Scale and Test Weights 

 

 Location Transportation of Equipment 

 

 also: Wet/Slick Conditions 

 Overhead Hazards, Obstructions
Livestock/Animal Scales Mechanical Analog Indicating 

EPO No. 12 

Rev. 3/02 12-2 

Inspection: 

Safety First!!! 

Check the inspection site carefully for safety hazards and take appropriate precautions. 

Use caution in moving in wet, slippery areas. 

Use personal protection equipment appropriate for the inspection site. 

Position safety cones and warning signs if necessary. 

Be sure that a first aid kit is available and that the kit is appropriate for the type of inspection activity. 

H-44 General Code and 

Scales Code References

1. Zero-load balance as found............................................................................................S.1.1., S.2.1.1., S.2.1.2., 

S.1.5.1., UR.4.1. 

2. General Considerations 

 Selection.................................................................................................................G.S.3., G-UR.1.1, UR.1. 

 Installation..............................................................................................................G-UR.2., 

 Supports for portable scale .....................................................................................UR.2.1 

 Protection from environment..................................................................................UR.2.3. 

 Foundation, supports, and clearance.......................................................................UR.2.4. 

 Access to weighing elements..................................................................................UR.2.5. 

 Stock racks .............................................................................................................UR.2.7. 

 

Check to be sure the scale supports are adequate to support 

the scale and test weights equal to the capacity of the scale !

 Accessibility for inspection, testing, and sealing....................................................G-UR.2.3. 

 Assistance...............................................................................................................G-UR.4.4. 

 Position, customer readability ................................................................................G-UR.3.3. 

 Maintenance, use, and environmental factors. 

 Facilitation of fraud ................................................................................................G-S.2. 

 Environment ...........................................................................................................G-UR.1.2. 

 Operation................................................................................................................G-UR.3.1. 

 Maintenance ...........................................................................................................G-UR.4.

 Maximum load .......................................................................................................UR.3.2. 

 Minimum load for livestock ...................................................................................UR.3.8. 

 Scale modification..................................................................................................UR.4.3. 

3. Marking .........................................................................................................................S.6.3., S.6.2 

 Nominal capacity .............................................................................S.6.1. (1/1/86) (livestock only)

 Nominal capacity must satisfy the relationship of: 

 nominal capacity ≤ CLC x (N - 0.5), where N = the number of sections in the scale 

Inspection (cont.): 
Livestock/Animal Scales Mechanical Analog Indicating 

EPO No. 12 

Rev. 3/02 12-3 

a. Marking requirements - all devices 

 Identification ..........................................................................................................G-S.1. 

 Name or ID of manufacturer................................................................................Retroactive 

 Model designation ...............................................................................................Retroactive 

 Model prefix ........................................................................................................(1/1/03)

 Nonrepetitive serial number ................................................................................(1/1/68) 

 Serial number prefix ............................................................................................(1/1/86) 

 NTEP CC prefix and number 

 (for devices that have an NTEP CC) ..................................................................(1/1/03) 

 Remanufacturer information, as appropriate: 

 name and ID of remanufacturer........................................................................(1/1/02) 

 model number if different from original model number ...................................(1/1/02) 

 Lettering .................................................................................................................G-S.7. 

 Operational controls, indications, and features.......................................................G-S.6. (1/1/77) 

 Visibility of identification ......................................................................................G-UR.2.1.1.

 Interchange or reversal of parts ..............................................................................G-S.4. 

 b. Marking requirements - weighing and indicating elements in same housing or covered on the same CC 

 (in addition to marking for all devices) ..................................................................S.6.3. 

 Accuracy class.....................................................................................................(1/1/86) 

 Nominal capacity.................................................................................................Retroactive

 Value of scale division with nominal capacity, if not apparent ...........................(1/1/83) 

 Value of "e" (if different from "d")......................................................................(1/1/86) 

 Temperature limits if other than -10 0

C to 40 0C (14 0F to 104 0F)......................(1/1/86) 

 Scales designed for special purposes...................................................................(1/1/86) 

 c. Marking requirements - indicating element not permanently attached or covered on separate CC 

 (in addition to marking for all device)....................................................................S.6.3. 

 Accuracy class.....................................................................................................(1/1/86) 

 Nominal capacity.................................................................................................Retroactive 

 Value of scale division with nominal 

 capacity, if not apparent ......................................................................................(1/1/83) 

 Value of "e" (if different from "d")......................................................................(1/1/86) 

 Temperature limits if other than 

 -10 0

C to 40 0C (14 0F to 104 0F) .........................................................................(1/1/86) 

 Scales designed for special purposes...................................................................(1/1/86) 

 Maximum number of scale divisions (nmax).........................................................(1/1/88) 

 d. Marking requirements - weighing and load receiving element not permanently attached or covered on separate 

CC (in addition to marking for all devices) ............................................................S.6.3. 

 Accuracy class.....................................................................................................(1/1/86) 

 Nominal capacity.................................................................................................Retroactive

 Nominal capacity on load receiving element.......................................................(1/1/89) (livestock only) 

 Concentrated Load Capacity (CLC) on the load- 

 receiving element (for scales manufactured prior 

 to 1989, the Section Capacity may be used as the 

 CLC; except that, the CLC marking must be 

 added at the time of modification to any scale 

 not previously marked)........................................................................................(1/1/89) (livestock only) 

 
Livestock/Animal Scales Mechanical Analog Indicating 

EPO No. 12 

Rev. 3/02 12-4 

Inspection (cont.):

 Marking requirements (cont.) - weighing and load receiving element not permanently attached or covered on 

separate CC (in addition to marking for all devices) .....................................................S.6.3. 

 Temperature limits if other than –10 0

C to 40 0C (14 0F to 104 0F) .....................(1/1/86) 

 Scales designed for special purposes...................................................................(1/1/86) 

 Maximum number of scale divisions (nmax).........................................................(1/1/88) 

 Minimum verification scale division for which 

 device complies with the requirements (emin or d) ...............................................(1/1/88) 

4. Indicating and recording elements. 

 Value of Scale Division..........................................................................................S.1.2.* (1/1/86) 

 Designation of accuracy class ................................................................................S.5.*, UR.1.1. 

 Weighbeams...........................................................................................................S.1.5. except S.1.5.5. 

 Poises......................................................................................................................S.1.6. 

 Dials and balance indicators1

..................................................................................S.1.3., S.1.4. 

 Damping means......................................................................................................S.2.5. except S.2.5.1. and 

S.2.5.2. 

 Appropriateness. 

 Indicating and recording elements..........................................................................G.S.5. except G-S.5.2.2. 

 Parameters for Accuracy Class...............................................................................S.5.2.(1/1/86)* 

 Selection.................................................................................................................UR.1.1. 

 Suitability ...............................................................................................................G-UR.1.1. 

 Recommended minimum load................................................................................UR.3.1.* 

 Maximum load .......................................................................................................UR.3.2. 

 Adjustable components ..........................................................................................S.1.10. 

5. Design of weighing elements.........................................................................................S.4. 

 

Pretest Determinations:

1. Tolerances. 

 Acceptance/maintenance ........................................................................................G-T.1., G-T.2. 

 Application.............................................................................................................G-T.3., G-T.4., T.N.2.1., 

T.N.2.3. 

 Ratio tests ............................................................................................................T.N.2.5. 

 

Tolerance values: Scale capacity 

 Determine number of scale divisions (n) ............................................................n = Value of scale division 

 if scale is marked with an accuracy designation. 

 Maintenance tolerance.....................................................................................T.N.3.1./Table 6 

 Acceptance tolerance.......................................................................................T.N.3.2. 

 Agreement of indications ................................................................................T.N.4 

 Repeatability ...................................................................................................T.N.5. 

 Unmarked scales..................................................................................................T.1.1. 

 Repeatability ...................................................................................................T.N.5. 

 Discrimination .....................................................................................................T.N.7.1.* 

Pretest Determinations (cont.):

 

1 A balance indicator with graduations having specific values shall be considered a dial. 
Livestock/Animal Scales Mechanical Analog Indicating 

EPO No. 12 

Rev. 3/02 12-5 

 Tolerances (cont). 

Sensitivity: 

 Marked scales.........................................................................................................T.N.6.1.(a), T.N.6.2. 

 Unmarked scales.....................................................................................................T.2.1., T.2.7., T.3.1.(a) or (c) 

2. Determine “used capacity.” 

For calculation in metric units: 

Multiply area of platform in square meters (length x width = area) by: 540 kilograms for cattle, 340 kilograms for 

calves and hogs, and 240 kilograms for sheep. 

For calculation in inch pound units: 

Multiply area of platform in square feet (length x width = area) by: 110 pounds for cattle, 70 pounds for calves and 

hogs, and 50 pounds for sheep. 

3. Minimum test weights and test loads.............................................................................N.3./Table 4

Carefully inspect electrical supply lines for test equipment for 

wear or damage; correct potentially hazardous conditions 

before use; protect lines from damage during use. 

Test Notes: 

Wear appropriate personal protection equipment such as safety shoes 

to prevent possible injury from falling weights and slipping on slick 

surfaces and a hard hat to prevent injury from overhead hazards.

1. For beam scales, balance small error weights on platform, the smallest weight equal to the 

 minimum tolerance applicable, and the total value of the weights equal to the tolerance at 

 maximum test load. 

2. Check repeatability of, and agreement between, indications throughout test. ...............G-S.5.2.2.(b), T.N.5. 

3. Recheck zero-load balance each time test load is removed. ..........................................N.1.9., G-UR.4.2. 

4. If the scale is equipped with a type-registering (TR) beam or printer, print ticket at each 

 test load .........................................................................................................................G-S.5.6., UR.1.3.(1/1/86) 

Test: 

WEAR SAFETY SHOES !

USE PROPER LIFTING TECHNIQUES !

1. Sensitivity test at zero load (for weighbeams only).......................................................N.1.4. 

Discrimination test at zero load (dials and balance indicators only)..............................N.1.5.(1/1/86) 
Livestock/Animal Scales Mechanical Analog Indicating 

EPO No. 12 

Rev. 3/02 12-6 

Test (cont.):

2. Increasing-load test. 

 Test to used capacity with the test load distributed .......................................................N.1.1. 

a. Beam scales. At a minimum, test at half and full capacity on fractional beam, 

 100-pound increments to 1000 pounds, and three other points on main weighbeam, 

 including used capacity. 

 

 Scales not equipped with a full capacity beam should be ratio tested using 

 standard weights on counterpoise hanger. At each test load, test scale counterpoise 

 weights by substituting them for standard counterpoise weights. If there is any notice- 

 able change in the indication, remove the scale weight from service until it can be determined 

 that it meets requirements in the Weight Code of NIST Handbook 44. 

When ratio testing, test poise and beam by the removal of standard weights from 

 the counterpoise hanger...........................................................................................N.1.7.

b. Dial scales. Test at 100-pound increments to 1000 pounds and at each quarter 

 of dial capacity. Test all unit or drop weights normally used.

3. Shift test. Can be conducted during increasing-load test. 

 Livestock scale with more than two sections.................................................................N.1.3.4. 

 For Livestock scales with more than two sections, conduct at least one shift test with a 

 Minimum test load of 12.5 percent of scale capacity anywhere on the load-receiving element 

 using the prescribed test patterns and maximum test loads specified below 

 Prescribe test pattern: An area of 1.2 meters (4 feet) in length and 3.0 meters (10 feet) in width or the width 

 of the scale platform, whichever is less, shall be loaded to no more than half of the concentrated 

 load capacity before loading the other side. 

 For test patterns less than 1.2 meters (4 feet) in length, determine the maximum loading by the formula 

 [(wheel base of test cart or length of test load divided by 48 in) x 0.9 x CLC]. 

 For test patterns that exceeds 1.2 meters (4 feet), the maximum test load applied shall not exceed CLC x 

 the largest r factor in table UR.3.2.1. 

 For weighing elements installed prior to January 1, 1989, the rated section capacity may be substituted for 

concentrated load capacity to determine maximum loading. 

 

 Multiple pattern loading: To test to the nominal capacity, multiple patterns may be 

 simultaneously loaded in a manner consistent with the method of use. 

 

 Other designs: Special design scales and those that are wider than 3.7 meters (12 feet) 

 shall be tested in a manner consistent with the method of use, 

 but following the principles described above.
Livestock/Animal Scales Mechanical Analog Indicating 

EPO No. 12 

Rev. 3/02 12-7 

Test (cont.):

 1.2 m 1.2 m 1.2 m 1.2 m 1.2 m 

 (4 ft) (4 ft) (4 ft) (4 ft) (4 ft) 

 

 Section Midway Section Midway Section 

 1 between 2 between 3 

 sections sections 

 1 and 2 2 and 3 

 

 Test load: The maximum test load applied to the prescribed test pattern shall not 

 exceed the concentrated load capacity (or for scales manufactured prior to January 1, 

 1989, the rated section capacity). 

 

 Note: When testing scales manufactured prior to January 1, 1989, caution should be 

 exercised when loading test weights equivalent to the rated section capacity onto 

 areas between sections. 

 

 Note: When loading the first section to be tested, it is recommended that observations be 

 made at each increment of test weight application. 

 Note: When loading the scale for testing one side of the test pattern shall be loaded to 

 no more than half of the concentrated load capacity 

 or test load before loading the other side. 

 Two-section livestock scales and animal scales ............................................................N.1.3.8. 

4. Sensitivity test at maximum test load (weighbeams and balance indicators only).........N.1.4. 

 Discrimination test at maximum test load (dials and balance indicators only) ..............N.1.5. 

5. Decreasing-load test (dials only) at one-half of maximum test load (at no less 

than one-half dial face capacity)...................................................................................N.1.2. 

6. Remove all test weights and determine any zero-load balance change .........................N.1.9., G-UR.4.2. 

7. Remove error weights and establish correct zero-load balance. 
Livestock and Animal Scales Equipped with Electronic Digital Indicators 

EPO No. 12E 

Rev. 3/02 12E-1 

 

Examination Procedure Outline for

Livestock and Animal Scales 

Equipped with Electronic Digital Indicators 

It is recommended that this outline be followed for livestock and animal scales equipped with electronic digital 

indicators. Requirements that apply only to scales marked with an accuracy class are indicated with an asterisk. 

Nonretroactive requirements are followed by the applicable date in parentheses. 

SAFETY NOTES 

When excerpting this Examination Procedure Outline for duplication, the "Safety Considerations" section and the 

"Glossary of Safety Key Phrases" should be duplicated and included with the outline. 

The inspector is reminded of the importance of evaluating potential safety hazards prior to an inspection and taking 

adequate precautions to avoid personal injury or damage to the device. The inspector should read and be familiar with 

the introductory section on safety found at the beginning of this publication. As a minimum, the following safety 

precautions should be noted and followed during the inspection. Definitions of each reminder are found in the "Glossary 

of Safety Key Phrases" at the back of this publication. 

Safety policies and regulations vary among jurisdictions. It is essential that inspectors or servicepersons be aware of 

all safety regulations and policies in place at the inspection site and to practice their employer’s safety policies. The 

safety reminders included in this EPO contain general guidelines useful in alerting inspectors and servicepersons to 

the importance of taking adequate precautions to avoid personal injury. These guidelines can only be effective in 

improving safety when coupled with training in hazard recognition and control. 

 Clothing Personal Protection Equipment 

 e.g., Safety Shoes 

 Electrical Hazards Hard Hat 

 

 

 First Aid Kit Safety Cones/Warning Signs 

 

 Lifting Support – for Scale and Test Weights 

 

 Location Transportation of Equipment 

 also: Wet/Slick Conditions 

 Overhead Hazards, Obstructions
Livestock and Animal Scales Equipped with Electronic Digital Indicators 

EPO No. 12E 

Rev. 3/02 12E-2 

Inspection: 

Safety First!!! 

Check the inspection site carefully for safety hazards and take appropriate precautions. 

Use caution in moving in wet, slippery areas. 

Use personal protection equipment appropriate for the inspection site. 

Position safety cones and warning signs if necessary. 

Be sure that a first aid kit is available and that the kit is appropriate for the type of inspection activity.

H-44 General Code and 

Scales Code References

1. Zero-load balance as found. If the device is not in balance, the user should be made 

 aware of paragraph UR.4.1. and a warning issued if necessary. If a ring scale and 

 a tare has been taken for a ring man, check accuracy of the tare taken .........................S.1.1., S.2.1.1., S.2.1.2. 

UR.4.1.,G-S.5.2.2.(d) 

(1/1/86)* 

2. General Considerations 

 Selection.................................................................................................................G.S.3., G-UR.1.1, UR.1. 

 Installation..............................................................................................................G-UR.2., 

 Supports for portable scale ..................................................................................UR.2.1. 

 Protection from environment...............................................................................UR.2.3. 

 Foundation, supports, and clearance....................................................................UR.2.4. 

 Access to weighing elements...............................................................................UR.2.5. 

 Stock racks ..........................................................................................................UR.2.7. 

 

Check to be sure the scale supports are adequate to support 

the scale and test weights equal to the capacity of the scale!

 Accessibility for inspection, testing, and sealing....................................................G-UR.2.3. 

 Assistance...............................................................................................................G-UR.4.4. 

 Position, customer readability ................................................................................G-UR.3.3. 

 Maintenance, use, and environmental factors. 

 Facilitation of fraud .............................................................................................G-S.2. 

 Environment ........................................................................................................G-UR.1.2.

 Operation.............................................................................................................G-UR.3.1. 

 Maintenance ........................................................................................................G-UR.4. 

Inspection (cont.): 
Livestock and Animal Scales Equipped with Electronic Digital Indicators 

EPO No. 12E 

Rev. 3/02 12E-3 

 Maintenance, use, and environmental factors (cont.). 

 Maximum load.....................................................................................................UR.3.2. 

 Minimum load for livestock ................................................................................UR.3.8. 

 Manual gross weight entries ................................................................................UR.3.9, S.1.12. 

 Scale modification ...............................................................................................UR.4.3. 

3. Marking .........................................................................................................................S.6.3., S.6.2. 

 Nominal capacity...........................................................................................................S.6.1. (1/1/86) (livestock only) 

 Nominal capacity must satisfy the relationship of: 

 nominal capacity ≤ CLC x (N - 0.5), where N = the number of sections in the scale. 

a. Marking requirements - all devices 

 Identification ..........................................................................................................G-S.1. 

 Name or ID of manufacturer................................................................................Retroactive 

 Model designation ...............................................................................................Retroactive 

 Model prefix ........................................................................................................(1/1/03)

 Nonrepetitive serial number ................................................................................(1/1/68) 

 Serial number prefix ............................................................................................(1/1/86) 

 NTEP CC prefix and number ..............................................................................(1/1/03) 

 (for devices that have an NTEP CC) 

 Remanufacturer information, as appropriate: 

 name and ID of remanufacturer .....................................................................(1/1/02) 

 model number if different from original model number ................................(1/1/02) 

 Lettering .................................................................................................................G-S.7. 

 Operational controls, indications, and features.......................................................G-S.6. (1/1/77) 

 Visibility of identification ......................................................................................G-UR.2.1.1.

 Interchange or reversal of parts ..............................................................................G-S.4. 

 b. Marking requirements - weighing and indicating elements in same housing or covered on the same CC 

 (in addition to marking for all devices) ..................................................................S.6.3 

 Accuracy class........................................................................................................(1/1/86) 

 Nominal capacity....................................................................................................Retroactive 

 Value of scale division with nominal capacity, if not apparent..............................(1/1/83) 

 Value of "e" (if different from "d") ........................................................................(1/1/86) 

 Temperature limits if other than –10 0

C to 40 0C (14 0F to 104 0F)........................(1/1/86) 

 Scales designed for special purposes......................................................................(1/1/86) 

 c. Marking requirements - indicating element not permanently attached or covered on separate CC 

 (in addition to marking for all device)....................................................................S.6.3 

 Accuracy class........................................................................................................(1/1/86) 

 Nominal capacity....................................................................................................Retroactive 

 Value of scale division with nominal capacity, if not apparent ..............................(1/1/83) 

 Value of "e" (if different from "d") ........................................................................(1/1/86) 

 Temperature limits if other than -10 0

C to 40 0C (14 0F to 104 0F).........................(1/1/86) 

 Scales designed for special purposes......................................................................(1/1/86) 

 Maximum number of scale divisions (nmax)............................................................(1/1/88) 
Livestock and Animal Scales Equipped with Electronic Digital Indicators 

EPO No. 12E 

Rev. 3/02 12E-4 

Inspection (cont.):

 d. Marking requirements - weighing and load receiving element not permanently attached or covered on separate 

CC (in addition to marking for all devices) ...........................................................S.6.3. 

 Accuracy class........................................................................................................(1/1/86) 

 Nominal capacity....................................................................................................Retroactive 

 Nominal capacity on load receiving element..........................................................(1/1/89) (livestock only)

 Concentrated Load Capacity (CLC) on the load-receiving element (for scales 

 manufactured prior to 1989, the Section Capacity may be used as the CLC; except 

 that, the CLC marking must be added at the time of modification to any scale 

 not previously marked)........................................................................................(1/1/89) (livestock only) 

 Temperature limits if other than -10 0

C to 40 0C (14 0F to 104 0F).........................(1/1/86) 

 Scales designed for special purposes......................................................................(1/1/86) 

 Maximum number of scale divisions (nmax)............................................................(1/1/88) 

 Minimum verification scale division for which 

 device complies with the requirements (emin or d)..................................................(1/1/88) 

e. Marking requirements - load cell with Certificate of Conformance 

 (in addition to marking for all devices)...................................................................S.6.3., S.5.4. (1/1/94)

 Note: Requires information on a data plate attached to the load cell or in 

 accompanying document. If a document is provided, the serial number shall 

 appear on the load cell and in the document...........................................................(1/1/88) 

 Manufacturer’s name or trademark, model designation, model prefix and serial 

 number and prefix shall also be marked on both the load cell and in 

 any accompanying documents................................................................................(1/1/91) 

 Accuracy class........................................................................................................(1/1/88) 

 Temperature limits if other than -10 0

C to 40 0C (14 0F to 104 0F).........................(1/1/86) 

 Maximum number of divisions...............................................................................(1/1/88) 

 “S” or “M” for single or multiple cell applications ................................................(1/1/88) 

 Direction of loading, if not obvious........................................................................(1/1/88) 

 Minimum dead load, maximum capacity, safe load limit, and load cell 

 verification interval, vmin ........................................................................................(1/1/88) 

4. Determination of Load Cell Suitability (applicable to load cells with an NTEP 

 Certificate of Conformance): 

a. The number of scale divisions (n) of the scale is less than or equal to the nmax 

 of the indicator or the load cells, whichever is less; e.g., if the indicator has an 

 nmax of 10,000 and the load cells have an nmax of 5,000, then the scale may use up 

 to 5,000 divisions. 

b. The load cell is approved for the required accuracy class. Note: A Class III 

 load cell may be used in a Class III L application; however the opposite is not true. 

c. The load cell is rated Single (S) or Multiple (M) use as appropriate to the application. 

Note: A load cell rated for single use may be used in a single or multiple load cell 

application; however, a load cell rated for multiple use cannot be used in a single 

 load cell application. 
Livestock and Animal Scales Equipped with Electronic Digital Indicators 

EPO No. 12E 

Rev. 3/02 12E-5 

Inspection (cont.):

Determination of Load Cell Suitability (cont.) 

d. The load cell complies with the requirements for temperature effect on zero-load 

 balance....................................................................................................................S.5.4., T.N.8.1 

Appendix to EPO 12-E 

 Note: Testing to determine the effect of temperature on zero-load balance cannot be 

 performed in the field; however, for purposes of field inspection, a load cell is 

 considered to comply with T.N.8.1.3. if the vmin value marked on the load cell is less than 

 or equal to the vmin value as calculated below based upon the d and N for the scale; 

 if it is not, the scale does not comply with T.N.8.1.3. 

 Full electronic scale with more than one load cell: The verification scale division vmin, 

 for the load cells must be less than or equal to the scale division, d, divided by the 

 square root of the number of load cells, N, used in the scale: 

 vmin < d 

 /N 

 Note: Maximum values of vmin for commonly encountered multiple load cell 

 scales are listed in the Appendix to EPO 12-E. 

 For scales with mechanical lever systems:

 vmin < d 

 /N x scale multiple 

5. Indicating and recording elements. 

 Value of scale division ...........................................................................................S.1.2. (1/1/86) 

 Weight units ...........................................................................................................S.1.2.1. (1/1/89) 

 Designation of accuracy class ................................................................................S.5.* 

 Value of graduated interval ....................................................................................G-S.5.3. 

 Marked devices ......................................................................................................UR.1.1.(a) 

 Unmarked devices ..................................................................................................UR.1.1.(b)(animal only) 

 Recorded scale division..........................................................................................UR.1.3. 

 Tare division value, if equipped with a keyboard1 .................................................S.2.3.(1/1/83) 

 Tare mechanism .....................................................................................................S.2.3.(1/1/83) 

 Appropriateness......................................................................................................G-UR.1.1. 

 Indicating and recording elements.......................................................................G.S.5. 

 Parameters for accuracy class..............................................................................S.5.2.(1/1/86)* 

 Selection ..............................................................................................................UR.1.

 Recommended minimum load .............................................................................UR.3.1.* 

 

 

1

 Generally, tare is not considered appropriate on these scales. If the device is located in an auction market and is a 

ring scale, a tare capability may be considered appropriate. 
Livestock and Animal Scales Equipped with Electronic Digital Indicators 

EPO No. 12E 

Rev. 3/02 12E-6 

Inspection (cont.): 

 Indicating and recording elements (cont.) 

 Maximum load.....................................................................................................UR.3.2. 

 Damping means ...................................................................................................S.2.5., S.2.5.1. 

 Adjustable components........................................................................................S.1.10. 

 Provision for sealing......................................................................................................S.1.11, G-S.8.(1/1/90), 

G-UR.4.5. 

 Manual gross weight entries..........................................................................................S.1.12.(1/1/93), 

UR.3.9.(livestock) 

6. Design of weighing elements.........................................................................................S.4. 

 

Pretest Determinations:

1. Tolerances. 

 Acceptance/maintenance ........................................................................................G-T.1., G-T.2. 

 Application.............................................................................................................G-T.3., G-T.4., T.N.2.1., 

T.N.2.3., T.N.2.4. 

 Tolerance values: Scale Capacity 

 Determine number of scale divisions (n)................................................................n = Value of scale division 

 If scale is marked with an accuracy designation. 

 Maintenance tolerance.........................................................................................T.N.3.1./Table 6 (Class III 

L–livestock scales, Class 

III – animal scales) 

 Acceptance tolerance...........................................................................................T.N.3.2. 

 Agreement of indications.....................................................................................T.N.4.1 

 Shift or section test ..............................................................................................T.N.4.4. 

 Repeatability........................................................................................................T.N.5. 

 Unmarked scales 

 Livestock scales...................................................................................................T.1.1. 

 Maintenance tolerance ...................................................................................T.N.3.1./Table 6 (Class III L) 

 Acceptance tolerance .....................................................................................T.N.3.2. 

 Agreement of indications...............................................................................T.N.4.1. 

 Shift or section test ........................................................................................T.N.4.4. 

 Repeatability..................................................................................................T.N.5. 

 Animal scales with 5000 or less scale divisions ..................................................T.1.1. 

 Maintenance tolerance ...................................................................................T.N.3.1./Table 6 (Class III) 

 Acceptance tolerance .....................................................................................T.N.3.2. 

 Agreement of indications...............................................................................T.N.4.1. 

 Repeatability..................................................................................................T.N.5. 

 Discrimination........................................................................................................T.N.7.2.
Livestock and Animal Scales Equipped with Electronic Digital Indicators 

EPO No. 12E 

Rev. 3/02 12E-7 

Pretest Determinations (cont.): 

2. Determine “used capacity.” 

For calculation in metric units: 

Multiply area of platform in square meters (length x width = area) by: 540 kilograms for cattle, 340 kilograms for 

calves and hogs, and 240 kilograms for sheep. 

For calculation in inch pound units: 

Multiply area of platform in square feet (length x width = area) by: 110 pounds for cattle, 70 pounds for calves and 

hogs, and 50 pounds for sheep. 

3. Minimum test weights and test loads.............................................................................N.3./Table 4

Carefully inspect electrical supply lines for test equipment for 

wear or damage; correct potentially hazardous conditions 

before use; protect lines from damage during use. 

Test Notes: 

Wear appropriate personal protection equipment such as safety shoes 

to prevent possible injury from falling weights and slipping on slick 

surfaces and a hard hat to prevent injury from overhead hazards.

1. Check repeatability of, and agreement between, indications throughout test. ...............G-S.5.2.2.(a), T.N.5. 

2. Recheck zero-load balance each time test load is removed. ..........................................N.1.9., G-UR.4.2. 

3. If the scale is equipped with a printer, print a ticket at each test load............................G-S.5.6., UR.1.3.(1/1/86)* 

 Check effectiveness of motion detection 

 Animal Scales > 2000 kg (5000 lb) capacity in service 

 prior to January 1, 1981 and all livestock scales .................................................S.2.5.1.(a) 

 All other animal scales ........................................................................................S.2.5.1.(b) 

4. If, during the conduct of the test, the performance of the device is questionable 

 with respect to the zone of uncertainty and the width of zero, tests may be 

 conducted to determine compliance...............................................................................N.1.5.(1/1/86)*,N.1.5.1., 

S.1.1.1. 

5. If the device is equipped with operational features such as manual weight entries 

or a scoreboard indication of average weight, unit price, total prices, etc.; 

check proper operation and appropriateness..................................................................G-UR.4.1., G-UR.4.2. 
Livestock and Animal Scales Equipped with Electronic Digital Indicators 

EPO No. 12E 

Rev. 3/02 12E-8 

Test: 

WEAR SAFETY SHOES !

USE PROPER LIFTING TECHNIQUES !

1. Discrimination test at zero-load, if deemed necessary and if environmental conditions 

 can be controlled............................................................................................................N.1.5.(1/1/86)*, N.1.5.1.* 

2. Increasing-load test. 

 Depending on test weights available, test as close to tolerance breakpoints 

 as possible ..............................................................................................................N.1.1. 

3. Shift test. Can be conducted during increasing-load test. 

Livestock scale with more than two sections..........................................................N.1.3.4. 

 For Livestock scales with more than two sections, conduct at least one shift test 

 with a minimum test load of 12.5 percent of scale capacity anywhere on the load- 

 receiving element using the prescribed test patterns and maximum test loads 

 specified below

 

Prescribe test pattern: An area of 1.2 meters (4 feet) in length and 3.0 meters (10 feet) in width 

or the width of the scale platform, whichever is less, shall be loaded to no more 

than half of the concentrated load capacity before loading the other side. 

 For test patterns less than 1.2 meters (4 feet) in length, determine the maximum loading 

 by the formula [(wheel base of test cart or length of test load divided 

 by 48 in) x 0.9 x CLC]. 

 For test patterns that exceeds 1.2 meter (4 feet), the maximum test load applied shall not 

 exceed CLC x the largest r factor in table UR.3.2.1. 

 For weighing elements installed prior to January 1, 1989, the rated section capacity 

 may be substituted for concentrated load capacity to determine maximum loading. 

 

 Multiple pattern loading: To test to the nominal capacity, multiple patterns may 

 be simultaneously loaded in a manner consistent with the method of use. 

Other designs: Special design scales and those that are wider than 3.7 meters (12 feet) 

 shall be tested in a manner consistent with the method of use, but following the 

 principles described above. 

 
Livestock and Animal Scales Equipped with Electronic Digital Indicators 

EPO No. 12E 

Rev. 3/02 12E-9 

Test (cont.):

 1.2 m 1.2 m 1.2 m 1.2 m 1.2 m 

 (4 ft) (4 ft) (4 ft) (4 ft) (4 ft) 

 Section Midway Section Midway Section 

 1 between 2 between 3 

 sections sections 

 1 and 2 2 and 3 

 Test load: The maximum test load applied to the prescribed test pattern shall not 

 exceed the concentrated load capacity (or for scales manufactured prior to January 1, 

 1989, the rated section capacity). 

 

 Note: When testing scales manufactured prior to January 1, 1989, caution should be 

 exercised when loading test weights equivalent to the rated section capacity onto 

 areas between sections. 

 

 Note: When loading the first section to be tested, it is recommended that observations be 

 made at each increment of test weight application. 

 Note: When loading the scale for testing one side of the test pattern shall be loaded to 

 no more than half of the concentrated load capacity or test load before loading the 

 other side. 

 Two-section livestock scales and animal scales .....................................................N.1.3.8. 

4. RFI/EMI test (if a problem is suspected).......................................................................G-N.2, G-UR.3.2., 

G-UR.4.2,G-UR.1.2., 

N.1.6., T.4., T.N.9.* 

 Radio Frequency Interference (RFI) 

Electromagnetic Interference (EMI) 

5. Discrimination test at maximum test load, if deemed necessary and if 

 environmental conditions can be controlled ..................................................................N.1.5.(1/1/86)*, N.1.5.1. 

6. Over capacity test (if practical)......................................................................................S.1.7. 

7. Decreasing-load test ......................................................................................................N.1.2. 

 Marked animal scales only .....................................................................................N.1.2.1.* 

 Livestock scales and unmarked animal scales........................................................N.1.2.2. 

8. Remove all test weights and determine any zero-load balance change .........................N.1.9., G-UR.4.2. 

9. Test for proper design of automatic zero-setting mechanism, if device is so equipped 

 Livestock scales...................................................................................................S.2.1.3.(a)(1/1/81) 

 Animal scales.......................................................................................................S.2.1.3.(c)(1/1/81) 
Livestock and Animal Scales Equipped with Electronic Digital Indicators 

EPO No. 12E 

Rev. 3/02 12E-10 

Test (cont.):

10. If device is equipped with a semi-automatic zero-setting mechanism (push button), 

test effectiveness of motion detection 

 Scales > 2000 kg (5000 lb) capacity in service prior to January 1, 1981.............S.2.1.2.(a) 

 All other livestock and animal scales ..................................................................S.2.1.2.(b) 

11. Establish correct zero-load balance. 
Livestock and Animal Scales Equipped with Electronic Digital Indicators 

EPO No. 12E 

Rev. 3/02 12E-11 

Appendix to EPO No. 12E

Maximum Values of vmin

 Multiple Load Cell Scales 

 (Table values are in pounds.) 

Load Scale Division 

Cells 1 lb 2 lb 5 lb 10 lb 20 lb 50 lb 100 lb

 

 2 0.71 1.41 3.54 7.07 14.1 35 70 

 4 0.50 1.00 2.50 5.00 10.0 25 50 

 6 0.41 0.82 2.04 4.08 8.2 20.4 41 

 8 0.35 0.71 1.77 3.54 7.1 17.7 35 

10 0.32 0.63 1.58 3.16 6.3 15.8 32 

12 0.29 0.58 1.44 2.89 5.8 14.4 29 

14 0.27 0.53 1.34 2.67 5.4 13.4 27 

Full electronic scales

Example: For a livestock scale with two sections (four load cells) and a displayed scale division of 5 lb, the maximum 

value permitted for each load cell is 2.5 lb. The calculation is shown below. If the value marked on the load cell is less 

than or equal to the value computed for the vmin, then the load cell is considered to comply with T.N.8.1.3. 

vmin ≤ d = 5 lb = 5 lb = 2.5 lb 

 /N /4 2 

Electromechanical Scales

Example: Calculate the multiple of the lever system from the ratios marked on the levers. Suppose the multiple for a 

livestock scale is 400:1 and that the scale has a scale division of 5 lb. Then the maximum value for the vmin of the load 

cell is 0.0125 lb. The calculation is shown below. If the load cell is marked with a vmin less than or equal to the 

calculated value, then the load cell is considered to comply with T.N.8.1.3. 

vmin ≤ d = 5 lb = 0.0125 lb 

scale multiple 4

 

EPO No. 13 

Vehicle and Axle-Load Scales Mechanical-Analog Indicating

Rev. 3/02 13-1 

 

Examination Procedure Outline for

 

Vehicle and Axle-Load Scales 

 Mechanical - Analog Indicating

 (Weighbeams and Dials)

It is recommended that this outline be followed for vehicle and axle-load scales equipped with weighbeams and/or 

mechanical dials. Requirements that apply only to scales marked with an accuracy class are indicated with an asterisk. 

Nonretroactive requirements are followed by the applicable date in parentheses. 

SAFETY NOTES 

When excerpting this Examination Procedure Outline for duplication, the "Safety Considerations" section and the

"Glossary of Safety Key Phrases" should be duplicated and included with the outline. 

The inspector is reminded of the importance of evaluating potential safety hazards prior to an inspection and taking 

adequate precautions to avoid personal injury or damage to the device. The inspector should read and be familiar with

the introductory section on safety found at the beginning of this publication. As a minimum, the following safety 

precautions should be noted and followed during the inspection. Definitions of each reminder are found in the

"Glossary of Safety Key Phrases" at the back of this publication. 

Safety policies and regulations vary among jurisdictions. It is essential that inspectors or servicepersons be aware

of all safety regulations and policies in place at the inspection site and to practice their employer’s safety policies.

The safety reminders included in this EPO contain general guidelines useful in alerting inspectors and

servicepersons to the importance of taking adequate precautions to avoid personal injury. These guidelines can

only be effective in improving safety when coupled with training in hazard recognition and control..

 Clothing Personal Protection Equipment 

 e.g., Safety Shoes 

 Electrical Hazards Hard Hat – for protection from overhead 

hazard 

 First Aid Kit 

 Safety Cones/Warning Signs 

 Lifting 

Support – for scale, test weights, and test 

 Location equipment 

 Transportation of Equipment 

 also: Wet/Slick Conditions 

 Chemicals, Petroleum 

 Products, and 

 Hazardous Materials 

 Overhead Hazards 

 Obstructions 
 

EPO No. 13 

Vehicle and Axle-Load Scales Mechanical-Analog Indicating

Rev. 3/02 13-2 

Inspection: 

Safety First 

 

H-44 General Code and

Scales Code References

1. Zero-load balance as found. 

 If the device is not in balance, the 

 user should be made aware of paragraph 

 UR.4.1. and a warning issued if necessary. ...................................................................S.1.1., S.2.1.1., S.2.1.2., 

S.1.5.1., UR.4.1. 

2. Indicating and recording elements. 

 Scale division, value (d) and number(n).................................................................S.1.2.*,S.5.*, 

UR.1., UR.1.1.(b), 

UR.1.3. (1/1/86) 

 Tare division value .................................................................................................S.2.3. (1/1/83) 

 Tare mechanism .....................................................................................................S.2.3. 

 Appropriateness of design 

 General ................................................................................................................G-S.5. 

 Weighbeams........................................................................................................S.1.5. except S.1 

 Poises...................................................................................................................S.1.6. 

 Dials and balance indicators1

...............................................................................S.1.3., S.1.4., S.1.7. 

 Damping means ...................................................................................................S.2.5. 

 Suitability ............................................................................................................S.5.2. (1/1/86)*, UR.1.1.(a)*, 

 UR.3.1.*,UR.3.2., 

UR.3.2.1, UR.3.3. 

 Customer readability, if applicable .....................................................................G-UR.3.3. 

 

1

A balance indicator with graduations having a specific value shall be considered a dial. 

Check the inspection site carefully for safety hazards and take appropriate precautions. 

Learn the nature of hazardous products used at or near the inspection site. 

Use caution in moving in wet, slippery areas. 

Use personal protection equipment appropriate for the inspection site. 

Position safety cones and warning signs if necessary. 

Be sure that a first aid kit is available and that the kit is appropriate for the type of inspection activity.
 

EPO No. 13 

Vehicle and Axle-Load Scales Mechanical-Analog Indicating

Rev. 3/02 13-3 

Inspection (cont.):

 Adjustable components .........................................................................................S.1.10. 

3. Marking .........................................................................................................................S.6.3., S.6.2 

Nominal capacity..........................................................................................................S.6.1. (1/1/86) 

 Nominal capacity must satisfy the relationship of: 

 nominal capacity ≤ CLC x (N - 0.5), where N = the number of sections in the scale 

a. Marking requirements - all devices 

 Identification ..........................................................................................................G-S.1. 

 Name or ID of manufacturer................................................................................Retroactive 

 Model designation ...............................................................................................Retroactive 

 Model prefix ........................................................................................................(1/1/03)

 Nonrepetitive serial number ................................................................................(1/1/68) 

 Serial number prefix ............................................................................................(1/1/86) 

 NTEP CC prefix and number ..............................................................................(1/1/03) 

 (for devices that have an NTEP CC) 

 Remanufacturer information, as appropriate: 

 name and ID of remanufacturer .....................................................................(1/1/02) 

 model number if different from original model numbe..................................(1/1/02) 

 Lettering .................................................................................................................G-S.7. 

 Operational controls, indications, and features.......................................................G-S.6. (1/1/77) 

 Visibility of identification ......................................................................................G-UR.2.1.1.

 Interchange or reversal of parts ..............................................................................G-S.4. 

 b. Marking requirements - weighing and indicating elements in same housing or covered on the same CC 

 (in addition to marking for all devices) ..................................................................S.6.3. 

 Accuracy class.....................................................................................................(1/1/86) 

 Nominal capacity.................................................................................................Retroactive

 Value of scale division with nominal capacity, if not apparent ...........................(1/1/83) 

 Value of "e" (if different from "d")......................................................................(1/1/86) 

 Temperature limits if other than -10 0

C to 40 0C (140F to 104 0F).......................(1/1/86) 

 Scales designed for special purposes...................................................................(1/1/86) 

 c. Marking requirements - indicating element not permanently attached or covered on separate CC 

 (in addition to marking for all device)....................................................................S.6.3. 

 Accuracy class.....................................................................................................(1/1/86) 

 Nominal capacity.................................................................................................Retroactive

 Value of scale division with nominal capacity, if not apparent ...........................(1/1/83) 

 Value of "e" (if different from "d")......................................................................(1/1/86) 

 Temperature limits if other than -10 0

C to 40 0C (140F to 104 0F).......................(1/1/86) N/A 

 Scales designed for special purposes...................................................................(1/1/86) 

 Maximum number of scale divisions (nmax).........................................................(1/1/88) 

 d. Marking requirements - weighing and load receiving element not permanently attached or covered on separate 

CC (in addition to marking for all devices) ............................................................S.6.3. 

 Accuracy class.....................................................................................................(1/1/86) 

 Nominal capacity.................................................................................................Retroactive

 Nominal capacity on load receiving element.......................................................(1/1/89) 

 Concentrated Load Capacity (CLC) on the load-receiving element (for scales 

 manufactured prior to 1989, the Section Capacity may be used as the 

 

Inspection (cont.):

 

Marking requirements - weighing and load receiving element not permanently attached or covered on separate CC 
 

EPO No. 13 

Vehicle and Axle-Load Scales Mechanical-Analog Indicating

Rev. 3/02 13-4 

(in addition to marking for all devices - cont.)......................................................................S.6.3. 

 CLC; except that, the CLC marking must be added at the time of modification to 

 any scale not previously marked) ........................................................................(1/1/89) 

 For combination vehicle/railway scales, marking must include both the nominal capacity 

 and the CLC for vehicle weighing and the nominal capacity and section capacity for 

 railway weighing .................................................................................................(1/1/00) 

 Temperature limits if other than -10 0

C to 40 0C (14 0F to 104 0F)......................(1/1/86) N/A 

 Scales designed for special purposes .............................................................(1/1/86) 

 Maximum number of scale divisions (nmax).........................................................(1/1/88) 

 Minimum verification scale division for which 

 device complies with the requirements (emin or d) ...............................................(1/1/88) 

4. Weighing and load-receiving elements..........................................................................S.4, UR.2.8.

 Access..................................................................................................................UR.2.5. 

5. Installation....................................................................................................................G-UR.2., UR.2.3., UR.2.4. 

 

6. Approaches 

 Vehicle scales.........................................................................................................UR.2.6.1. (1/1/76) 

 Axle-load scales .....................................................................................................UR.2.6.2. 

7. Maintenance, use, and environmental factors. 

 Facilitation of fraud ................................................................................................G-S.2. 

 Environment ...........................................................................................................G-UR.1.2. 

 Operation................................................................................................................G-UR.3.1. 

 Maintenance ...........................................................................................................G-UR.4.

 Maximum load .......................................................................................................UR.3.2. 

 Single draft vehicle weighing.................................................................................UR.3.3. 

 Minimum load ........................................................................................................UR.3.7. 

 Scale modification..................................................................................................UR.4.3. 

8. Assistance .....................................................................................................................G-UR.4.4. 

Pretest Determinations:

1. Tolerances. 

 Acceptance/maintenance ........................................................................................G-T.1., G-T.2. 

 Application ............................................................................................................T.N.2.1., T.N.2.3. 

Check to be sure the scale supports are adequate 

to support the scale, test equipment, and test 

weights equal to the capacity of the scale.
 

EPO No. 13 

Vehicle and Axle-Load Scales Mechanical-Analog Indicating

Rev. 3/02 13-5 

Pretest Determinations (cont.):

Tolerances values: 

 Scales marked with an accuracy class ...........................................................T.N.3.1./Table 6 (Class III L), 

T.N.3.2., T.N.4. (except 

T.N.4.5.), T.N.5. 

 Scales not marked with an accuracy class......................................................T.1.1., T.N.3.1./Table 6 

(Class III L), T.N.3.2., 

T.N.4. (except T.N.4.5.), 

T.N.5. 

 Discrimination........................................................................................................T.N.7.1.* 

 Sensitivity: 

 Scales marked......................................................................................................T.N.6.1.(a), T.N.6.2. 

 Scales not marked................................................................................................T.2.1., T.2.7., T.3.(a) or (c) 

Note: Some TN tolerances apply to unmarked vehicle scales (See NIST HB 44 Table T.1.1.) 

2. Determine maximum test load to be applied during test: a test load not to exceed marked 

 Concentrated Load Capacity (or for scales manufactured prior to January 1, 1989, 

 the marked Section Capacity) may be applied to any section or between any two sections. 

 A test load of 100 percent of capacity may be distributed over the entire platform. 

3. Minimum test weights and test loads.............................................................................N.3., Table 4 

Test Notes:

 

1. If beam scale, balance small error weights on the platform, the smallest weight equal 

 to the minimum tolerance value and the total value of the weights being equal to 

 the tolerance value at maximum test load. 

Test Notes (cont.):

Carefully inspect electrical supply lines and 

test equipment for wear or damage; correct 

potentially hazardous conditions before use;

protect lines from damage during use.

Wear appropriate personal protection equipment such

as safety shoes to prevent possible injury from falling 

weights and slipping on slick surfaces and a 

hard hat to prevent injury from overhead hazards.
 

EPO No. 13 

Vehicle and Axle-Load Scales Mechanical-Analog Indicating

Rev. 3/02 13-6 

2. Check repeatability of, and agreement between, indications throughout the test ..........T.N.5., G-S.5.2.2.(b) 

3. Recheck zero-load balance each time test load is removed. ..........................................N.1.9., G-UR.4.2. 

4. If the scale is equipped with a type-registering (T.R.) beam or a printer, 

 print ticket at each test load..... ......................................................................................G-S.5.6., UR.1.3. (1/1/86)*, 

G-S.5.2.2.(b) 

Test: 

 

1. Sensitivity test at zero load (for weighbeams and balance indicators only) ..................N.1.4. 

 Discrimination (dials and balance indicators with graduations having a 

 specific value only)........................................................................................................N.1.5. (1/1/86)* 

2. Increasing-load and shift (section) test. .........................................................................N.1.1. 

 a. If beam scale, test at not less than two points on each weighbeam. 

 b. If automatic-indicating scale, test at not less than three points on reading face, 

 including all possible quarters of the reading-face capacity. Test all unit weights 

 possible. 

 

 c. For vehicle scales with more than two sections, conduct at least one shift test with a 

 minimum test load of 12.5 percent of scale capacity anywhere on the load-receiving element 

 using the prescribed test patterns and maximum test loads specified below. .........N.1.3.4. 

Prescribe test pattern: An area of 1.2 meters (4 feet) in length and 3.0 meters (10 feet) in width or 

the width of the scale platform, whichever is less, shall be loaded to no more than half 

of the concentrated load capacity before loading the other side. 

 For test patterns less than 1.2 meters (4 feet) in length, determine the maximum loading by the 

 formula [(wheel base of test cart or length of test load divided by 48 in) x 0.9 x CLC]. 

 For test patterns that exceeds 1.2 meters (4 feet), the maximum test load applied shall not 

 exceed CLC x the largest r factor in table UR.3.2.1. 

 For weighing elements installed prior to January 1, 1989, the rated section capacity 

 may be substituted for concentrated load capacity to determine maximum loading. 

 Multiple pattern loading: To test to the nominal capacity, multiple patterns may 

 be simultaneously loaded in a manner consistent with the method of use. 

 

Test (cont.): 

 Other designs: Special design scales and those that are wider than 3.7 meters (12 feet) shall 

WEAR SAFETY SHOES! 

USE PROPER LIFTING TECHNIQUES!
 

EPO No. 13 

Vehicle and Axle-Load Scales Mechanical-Analog Indicating

Rev. 3/02 13-7 

 be tested in a manner consistent with the method of use, but following the principles 

 described above. 

 1.2 m 1.2 m 1.2 m 1.2 m 1.2 m 

 (4 ft) (4 ft) (4 ft) (4 ft) (4 ft) 

 Section Midway Section Midway Section 

 1 between 2 between 3 

 sections sections 

 1 and 2 2 and 3 

 Test load: The maximum test load applied to the prescribed test pattern shall not 

 exceed the concentrated load capacity (or for scales manufactured prior to January 1, 

 1989, the rated section capacity). 

 Note: When testing scales manufactured prior to January 1, 1989, caution should be 

 exercised when loading test weights equivalent to the rated section capacity onto 

 areas between sections. 

 Note: When loading the first section to be tested, it is recommended that observations be 

 made at each increment of test weight application. 

 Note: When loading the scale for testing the side of the test pattern shall be loaded to 

 no more than half of the concentrated load capacity or test load before loading the 

 other side. 

3. Decreasing-load test (dials only), at one-half of maximum test load (at no less than one-half 

 dial-face capacity). ........................................................................................................N.1.2., N.1.2.2. 

4. Strain-load test on at least two sections.........................................................................N.1.1. (See Appendix B) 

Position vehicle on one end of scale; bring scale to balance by addition or removal 

of weights. Note this as reference point. Distribute test weights on other end of scale. 

Determine error using the reference point noted above. The tolerances are selected 

based upon the value of the test-weight load only. 

5. Sensitivity test at maximum test load (weighbeams and balance indicators only).........N.1.4. 

 Discrimination (dials and balance indicators with graduations having a specific 

 value only).....................................................................................................................N.1.5. (1/1/86)* 

6. Counterpoise-weight test, if device is so equipped........................................................NIST Handbook 44 

Weights Code 

Test (cont.):

7. Remove test load and determine any zero-load balance change....................................N.1.9., G-UR.4.2. 
 

EPO No. 13 

Vehicle and Axle-Load Scales Mechanical-Analog Indicating

Rev. 3/02 13-8 

8. Remove error weights and establish correct zero-load balance. 
 

EPO No. 13 

Vehicle and Axle-Load Scales Mechanical-Analog Indicating

Rev. 3/02 13-9 

Appendix B to EPO No. 13 

Strain-Load Method of Testing

 (Excerpts from NBS Handbook 94) 

Description of Test. When the supply of test weights is inadequate, the principle involved in the use of strain loads is 

that the known test load is first applied when the scale is carrying no other load (this is frequently referred to as the "light 

test"), and is subsequently applied one or more times when the scale is under some additional, but unknown, load that 

stresses the parts as they are normally stressed under ordinary operating conditions. Under this method, the actual values 

of the strain loads - which may consist of miscellaneous material, loaded vehicles, grain in a hopper, and the like - are 

immaterial and are not determined, the strain loads being simply "balanced out" by any convenient means. (The regular 

balancing means of the scale could be utilized when arriving at the final balance for a strain load, but this has the 

disadvantage that the scale cannot then be checked at the conclusion of the test for a possible shift of its zero-load 

balance; for this reason, use of the regular balancing means is not recommended here.) Thus, after carrying the light test 

of a motor-truck scale, for instance, as far as may be done with the test weights available, and assuming that it is next 

desired to make a test in the region up to one-half the nominal scale capacity, the test weights would be removed and a 

vehicle would be driven onto the platform and the scale brought to a balance; this vehicle would have been so selected 

that the sum of its gross weight and the total value of the test weights would approximate one-half the nominal capacity 

of the scale. The test weights would then be added, in one or in several increments, and it would be observed whether or 

not the scale properly indicated the value of each increment of test weights added. Following this, another strain load 

would be added, of such a value that the combined weight of the strain load and test weights would approximate the 

value in the region of which it is desired to make the next test; this strain load would then be balanced out and the test 

weights subsequently added as in the earlier part of the test. This operation may be repeated any desired number of times 

as long as the gross load does not exceed the weighing capacity of the scale; however, assuming that a reasonably 

satisfactory amount of test weights is available, not more than two strain loads will ordinarily be utilized, the scale being 

tested light and when loaded to approximately one-half and full capacities. 

Tolerance Application on Strain-Load Tests. In the strain-load method, observed errors are errors on the "testweight load only," since before each application of the test weight load the strain load of unknown value has been 

balanced out; accordingly, the tolerances to be applied are to be selected according to the value of the "test-weight 

load" in each instance of an accuracy observation under the strain-load method. 
Vehicle and Axle-Load Scales Equipped with Electronic Digital Indicators 

EPO No. 13E 

Rev. 3/02 13E- 1

 

 

Examination Procedure Outline for 

Vehicle and Axle-Load Scales 

Equipped with Electronic Digital Indicators 

It is recommended that this outline be followed for vehicle and axle-load scales equipped with electronic digital 

indicators. Requirements that apply only to scales marked with an accuracy class are indicated with an asterisk. 

Nonretroactive requirements are followed by the applicable date in parentheses. 

SAFETY NOTES 

 

When excerpting this Examination Procedure Outline for duplication, the "Safety Considerations" section and

the "Glossary of Safety Key Phrases" should be duplicated and included with the outline. 

The inspector is reminded of the importance of evaluating potential safety hazards prior to an inspection

and taking adequate precautions to avoid personal injury or damage to the device. The inspector should read and

be familiar with the introductory section on safety found at the beginning of this publication. As a minimum, the

following safety precautions should be noted and followed during the inspection. Definitions of each reminder are 

found in the "Glossary of Safety Key Phrases" at the back of this publication. 

Safety policies and regulations vary among jurisdictions. It is essential that inspectors or servicepersons be

aware of all safety regulations and policies in place at the inspection site and to practice their employer’s safety

policies. The safety reminders included in this EPO contain general guidelines useful in alerting inspectors

and servicepersons to the importance of taking adequate precautions to avoid personal injury. These guidelines

can only be effective in improving safety when coupled with training in hazard recognition and control.

 Clothing Personal Protection Equipment 

 e.g., Safety Shoes 

 Electrical Hazards Hard Hat – for protection from 

 overhead hazards 

 First Aid Kit 

 Safety Cones/Warning Signs 

 Lifting 

 Support – for scale, test weights, & test 

 Location equipment 

 Transportation of Equipment

 also: Wet/Slick Conditions 

 Chemicals, Petroleum Products 

 & Hazardous Materials 

 Overhead Hazards 

 Obstructions 

 
Vehicle and Axle-Load Scales Equipped with Electronic Digital Indicators 

EPO No. 13E 

Rev. 3/02 13E- 2

Inspection:

Safety First 

H-44 General Code and

Scales Code References

1. Zero-load balance as found. If the device is not in balance, the user should be 

made aware of paragraph UR.4.1. and a warning issued if necessary. ..........................G-S.5.2.2.(d)(1/1/86)* , S.1.1., 

S.2.1.1., S.2.1.2., UR.4.1., 

S.2.1.3.1. (1/1/01) 

2. Indicating, and recording elements. 

 Scale division, value (d) and number (n)................................................................G-S.5.3., S.1.2.*, S.1.2.1. 

(1/1/89), S.5*, S.5.4. 

(1/1/94), UR.1., 

UR.1.1.(b) UR.1.3. 

(1/1/86) 

 Rounding ................................................................................................................G-S.5.2.2.(c) 

 Tare division value .................................................................................................S.2.3. (1/1/83) 

 Tare mechanism .....................................................................................................S.2.3.(1/1/83) 

 Damping means......................................................................................................S.2.5., S.2.5.1.(a) 

 Appropriateness......................................................................................................G-S.5., S.5.2. (1/1/86)*, 

UR.1.1.(a)*, UR.3.1.*, 

UR.3.2., UR.3.3. 

 Customer readability, if applicable.........................................................................G-UR.3.3. 

 Adjustable components ..........................................................................................S.1.10. 

 Provision for sealing...............................................................................................S.1.11. (1/1/90), G-S.8. 

(1/1/90), G-UR.4.5. 

 Check the inspection site carefully for safety hazards and take appropriate precautions.

 Learn the nature of hazardous products used at or near the inspection site.

 Use caution in moving in wet, slippery areas.

 Use personal protection equipment appropriate for the inspection site.

 Position safety cones and warning signs if necessary.

 Be sure that a first aid kit is available and that the kit is appropriate for the type of inspection activity.
Vehicle and Axle-Load Scales Equipped with Electronic Digital Indicators 

EPO No. 13E 

Rev. 3/02 13E- 3

Inspection (cont.):

3. Marking .........................................................................................................................S.6.3., S.6.2. 

 Nominal capacity...........................................................................................................S.6.1. (1/1/86) 

 Nominal capacity must satisfy the relationship of: 

 nominal capacity ≤ CLC x (N - 0.5), where N = the number of sections in the scale 

 a. Marking requirements - all devices 

 Identification ..........................................................................................................G-S.1. 

 Name or ID of manufacture.................................................................................Retroactive 

 Model designation ...............................................................................................Retroactive 

 Model prefix ........................................................................................................(1/1/03)

 Nonrepetitive serial number ................................................................................(1/1/68) 

 Serial number prefix ............................................................................................(1/1/86) 

 NTEP CC prefix and number ..............................................................................(1/1/03) 

 (for devices that have an NTEP CC) 

 Remanufacturer information, as appropriate: 

 name and ID of remanufacturer .....................................................................(1/1/02) 

 model number if different from original model number ................................(1/1/02) 

 Lettering .................................................................................................................G-S.7. 

 Operational controls, indications, and features.......................................................G-S.6. (1/1/77) 

 Visibility of identification ......................................................................................G-UR.2.1.1.

 Interchange or reversal of parts ..............................................................................G-S.4. 

 b. Marking requirements - weighing and indicating elements in same housing or covered on the same CC 

 (in addition to marking for all devices) ..................................................................S.6.3. 

 Accuracy class.....................................................................................................(1/1/86) 

 Nominal capacity.................................................................................................Retroactive

 Value of scale division with nominal capacity, if not apparent ...........................(1/1/83) 

 Value of "e" (if different from "d")......................................................................(1/1/86) 

 Temperature limits if other than -10 0

C to 40 0C (140F to 104 0F)......................(1/1/86) 

 Scales designed for special purposes...................................................................(1/1/86) 

 c. Marking requirements - indicating element not permanently attached or covered on separate CC 

 (in addition to marking for all device)....................................................................S.6.3. 

 Accuracy class.....................................................................................................(1/1/86) 

 Nominal capacity.................................................................................................Retroactive

 Value of scale division with nominal capacity, if not apparent ...........................(1/1/83) 

 Value of "e" (if different from "d")......................................................................(1/1/86) 

 Temperature limits if other than -10 0

C to 40 0C (14 0F to 104 0F)......................(1/1/86) 

 Scales designed for special purposes...................................................................(1/1/86) 

 Maximum number of scale divisions (nmax).........................................................(1/1/88) 

 d. Marking requirements - weighing and load receiving element not permanently attached or covered on separate 

 CC (in addition to marking for all devices) ..............................................................S.6.3. 

 Accuracy class.....................................................................................................(1/1/86) 

 Nominal capacity.................................................................................................Retroactive

 Nominal capacity on load receiving element.......................................................(1/1/89) (livestock only) 

 
Vehicle and Axle-Load Scales Equipped with Electronic Digital Indicators 

EPO No. 13E 

Rev. 3/02 13E- 4

Inspection (cont.): 

 Marking requirements - weighing and load receiving element not permanently attached or covered on separate CC 

 (in addition to marking for all devices - cont.) ..............................................................S.6.3. 

 Concentrated Load Capacity (CLC) on the load-receiving element (for scales 

 manufactured prior to 1989, the Section Capacity may be used as the CLC; 

 except that, the CLC marking must be added at the time of modification to any scale 

 not previously marked)........................................................................................(1/1/89) (livestock only) 

 Temperature limits if other than -10 0

C to 40 0C (14 0F to 104 0F)......................(1/1/86) 

 Scales designed for special purposes...................................................................(1/1/86) 

 Maximum number of scale divisions (nmax).........................................................(1/1/88) 

 Minimum verification scale division for which 

 device complies with the requirements (emin or d) ...............................................(1/1/88) 

e. Marking requirements - load cell with Certificate of Conformance 

 (in addition to marking for all devices) ..................................................................S.6.3., S.5.4. (1/1/94) 

 Note: Requires information on a data plate attached to the load cell or in 

 accompanying document. If a document is provided, the serial number shall 

 appear on the load cell and in the document........................................................(1/1/88) 

 Manufacturer’s name or trademark, model designation, model prefix and 

 serial number and prefix shall also be marked on both the load cell and in 

 any accompanying documents.............................................................................(1/1/91) 

 Accuracy class.....................................................................................................(1/1/88) 

 Temperature limits if other than -10 0

C to 40 0C (14 0F to 104 0F)......................(1/1/86) 

 Maximum number of divisions............................................................................(1/1/88) 

 “S” or “M” for single or multiple cell applications..............................................(1/1/88) 

 Direction of loading, if not obvious.....................................................................(1/1/88) 

 Minimum dead load, maximum capacity, safe load limit, and load cell 

 verification interval, vmin......................................................................................(1/1/88) 

4. Installation.....................................................................................................................UR.2.3., UR.2.4., G-UR.2. 

5. Weighing and load receiving elements..........................................................................S.4., UR.2.8. 

 Access ....................................................................................................................UR.2.5. 

6. Load cell installation 

 Full electronic scale................................................................................................T.N.8.1.3., S.5.4. (1/1/94) 

Appendix to EPO 13-E 

 

Check to be sure the scale supports are adequate 

to support the scale, test equipment, and test 

weights equal to the capacity of the scale !
Vehicle and Axle-Load Scales Equipped with Electronic Digital Indicators 

EPO No. 13E 

Rev. 3/02 13E- 5

Inspection (cont.):

 Number of scale divisions, n, < nmax of the indicator or load cells, whichever is less. 

 Verification scale division, vmin, for the load cells must be less than or equal to the scale division, 

 d, divided by the square root of the number of load cells, N, used in the scale: 

 vmin < d 

/N 

 NOTE: Compliance with T.N.8.1.3. cannot be determined in the field. The vmin value on 

 the load cell is used to determine compliance with T.N.8.1.3. The vmin value marked on the 

 load cell must be less than or equal to the vmin value in the table of Appendix A of this 

 EPO based upon the d and N for the scale; if it is not, the scale does not comply with 

 T.N.8.1.3. (See also 1988 OWM paper on "Device Regulation Under the New Scales Code.") 

 For mechanical lever systems with a single load cell: 

 vmin < d 

scale multiple 

 Note: Maximum values of vmin for commonly encountered multiple load cell scales are 

 listed in the Appendix to EPO 13E. 

7. Approaches 

Vehicle scales.....................................................................................................UR.2.6.1. (1/1/76) 

Axle-load scales .................................................................................................UR.2.6.2. 

8. Maintenance, use, and environmental factors. 

 Facilitation of fraud .............................................................................................G-S.2. 

 Environment ........................................................................................................G-UR.1.2.

 Operation.............................................................................................................G-UR.3.1. 

 Maintenance ........................................................................................................G-UR.4. 

 Maximum load.....................................................................................................UR.3.2. 

 Single draft vehicle weighing ..............................................................................UR.3.3. 

 Manual gross weight entries ................................................................................UR.3.9, S.1 

 Minimum load .....................................................................................................UR.3.7. 

 Scale modification ......................................................................................................UR.4.3. 

9. Assistance......................................................................................................................G-UR.4.4. 

Pretest Determinations:

1. Tolerances: 

 Acceptance/maintenance ........................................................................................G-T.1., G-T.2. 

 Application: 

Scales marked with an accuracy class............................................................T.N.2.1., T.N.2.3., T.N.2.4. 
Vehicle and Axle-Load Scales Equipped with Electronic Digital Indicators 

EPO No. 13E 

Rev. 3/02 13E- 6

Pretest Determinations (cont.):

 Tolerance values: 

 Scales marked with an accuracy class............................................................T.N.3.1./Table 6 (Accuracy 

Class III L), T.N.3.2. 

Scales not marked with an accuracy class......................................................T.1.1., T.N.3.1./Table 6 

(Class III L), T.N.3.2., 

T.N.4.1., T.N.4.4., T.N.5. 

Note: Some TN tolerances apply to unmarked vehicle scales, see NIST HB 44 Table T.1.1.) 

 Discrimination........................................................................................................T.N.7.2. 

2. Determine maximum test load to be applied during test: A test load not to exceed 

 marked concentrated load capacity (or for scales manufactured prior to January 1, 1989, 

 the marked section capacity) may be applied to any section or between any two sections. 

 A test load of 100 percent of capacity may be distributed over the entire platform. 

3. Minimum test weights and test loads.............................................................................N.3., Table 4 

 

Test Notes:

 

1. Check repeatability of, and agreement between, indications throughout test. ...............T.N.5., G-S.5.2.2.(a), 

G-S.5.2.2.(c) 

2. Recheck zero-load balance each time test load is removed ...........................................N.1.9., G-UR.4.2. 

3. If the scale is equipped with a printer, print ticket at each test load. If the device will 

 print only one load without returning to "zero,” check printer with at least four different 

 loads at convenient times during test. Check effectiveness of motion detection. .........G-S.5.6., S-2.5.1.(a), UR.1.3. 

(1/1/86)* 

Carefully inspect electrical supply lines for 

test equipment for wear or damage; correct 

potentially hazardous conditions before use;

protect lines from damage during use.

Wear appropriate personal protection equipment such

as safety shoes to prevent possible injury from falling 

weights and slipping on slick surfaces and a 

hardhat to prevent injury from overhead hazards. 
Vehicle and Axle-Load Scales Equipped with Electronic Digital Indicators 

EPO No. 13E 

Rev. 3/02 13E- 7

Test Notes (cont.): 

4. If, during the conduct of the test, the performance of the device is questionable 

 with respect to the zone of uncertainty and the width of zero, additional tests may be con- 

 ducted to determine compliance. ...................................................................................N.1.5. (1/1/86)*, N.1.5.1.*, 

S.1.1.1. 

5. If the device is equipped with operational features such as programmable tare, 

 multiple tare memory, weigh-in/weigh-out, or multiple weighing elements, check 

 proper operation and appropriateness. ..........................................................................Type Evaluation Handbook 

Test: 

 

1. Discrimination test at or near zero load, if deemed necessary and if environmental 

 Conditions can be controlled .........................................................................................N.1.5. (1/1/86)*, N.1.5.1.* 

2. Test for proper configuration of automatic zero-setting mechanism, if device is 

 so equipped....................................................................................................................S.2.1.3.(b) (1/1/81) 

S.2.1.3.1. (1/1/01) 

3. If equipped with a semi-automatic zero-setting mechanism (push button), test 

 effectiveness of motion detection ..................................................................................Type Evaluation Handbook; 

S.2.1.2.(a) 

4. Check proper design of tare auto-clear, if device is so equipped...................................S.2.3. (including note for auto 

 clear 1/1/83) 

5. Establish correct zero-load balance. 

6. Increasing-load and shift (section) test ...........................................................................N.1.1., N.1.3.4. 

 For vehicle scales with more than two sections, conduct at least one shift test with a 

 minimum test load of 12.5 percent of scale capacity anywhere on the load receiving 

 element using the prescribed test patterns and maximum test loads specified below. 

 Prescribed Test pattern: An area of 1.2 meters (4 feet) in length and 3.0 meters (10 feet) in width 

 or the width of the scale platform, whichever is less. When loading the scale for testing, 

 one side of the test pattern shall be loaded to no more than one-half of the concentrated 

 load capacity before loading the other side. 

 For test patterns less than 1.2 meters (4 feet) in length, determine the maximum loading by the formula: 

 [(wheelbase of test cart or length of test load ÷ 48 in) x 0.9 x CLC] 

WEAR SAFETY SHOES !

USE PROPER LIFTING TECHNIQUES !
Vehicle and Axle-Load Scales Equipped with Electronic Digital Indicators 

EPO No. 13E 

Rev. 3/02 13E- 8

Test (cont.):

 For test patterns that exceed 1.2 meters (4 feet), the maximum test load applied shall not 

 exceed CLC x the largest r factor in Table UR.3.2. 

 Multiple pattern loading: To test to the nominal capacity, multiple patterns may be 

 simultaneously loaded in a manner consistent with the method of use. 

 Other designs: Special design scales and those that are wider than 3.7 meters (12 feet) shall 

 be tested in a manner consistent with the method of use but following the principles 

 described above. 

 Test load: The maximum test load applied to the prescribed test pattern shall not 

 exceed the concentrated load capacity (or for scales manufactured prior to 

 January 1, 1989, the rated section capacity). 

 Note: When testing scales manufactured prior to January 1, 1989, caution should be 

 exercised when loading test weights equivalent to the rated section capacity onto areas 

 between sections. 

 Note: When loading the first section to be tested, it is recommended that observations 

 be made at each increment of test weight application. 

 Note: For weighing elements installed prior to 1/1/89, the rated section capacity may 

 be substituted for concentrated load capacity to determine maximum loading. 

 Note: When loading the scale for testing, one side of the test pattern shall be loaded to 

 no more than half of the concentrated load capacity or test load before loading the 

 other side. 

 1.2 m 1.2 m 1.2 m 1.2 m 1.2 m 

 (4 ft) (4 ft) (4 ft) (4 ft) (4 ft) 

 Section Midway Section Midway Section 

 1 between 2 between 3 

 sections sections 

 1 and 2 2 and 3 
Vehicle and Axle-Load Scales Equipped with Electronic Digital Indicators 

EPO No. 13E 

Rev. 3/02 13E- 9

Test (cont.) 

7. RFI/EMI Test. 

 To test for EMI, use procedures outlined in SMA Test Procedures1

 . To test for effects 

 of RFI, use equipment found at the site in a manner that is usual and customary .........G-N.2., G-UR.3.2., G-UR.4.2., 

 G-UR.1.2., N.1.6., T.4., 

 T.N.9.* 

 Radio Frequency Interference (RFI) 

Electromagnetic Interference (EMI) 

8. Decreasing-load test, at one-half of maximum test load................... .............. .............N1.2., N.1.2.2. 

9. Strain-load test on at least two sections; tolerance on test weight load only .................N.1.1. (See Appendix B at the 

 end of this EPO) 

 Position vehicle on one end of scale; Using error weights, determine reference point 

 within the displayed division. Distribute test weights on other end of scale. 

 Determine error-using reference point noted above. The tolerances are selected 

 based upon the value of the test load only. 

10. Discrimination test at maximum test load, if deemed necessary and if environmental 

 conditions are controlled ...............................................................................................N.1.5. (1/1/86)*, N.1.5.1.* 

11. Over-capacity test (if practical) .....................................................................................S.1.7. 

12. Recheck zero-load balance change................................................................................N.1.9., G-UR.4.2. 

 

1

These procedures, developed by the Scale Manufacturers Association, were adopted by the National Conference on Weights and 

Measures as part of the Final Report of the Committee on Specifications and Tolerances 63rd annual meeting, 1978 (copies of 

the 1978 procedures are available). Also reference SMA Recommendation on Electrical Disturbance – SMA RED-0499 (copies 

of SMA RED-0499 are available at www.scalemanufacturers.org) 
Vehicle and Axle-Load Scales Equipped with Electronic Digital Indicators 

EPO No. 13E 

Rev. 3/02 13E- 10

Appendix A to EPO No. 13E 

Maximum Values of 

 Multiple Load Cell Scales 

 (Table values are in pounds.) 

Load Scale Division 

Cells 1 lb 2 lb 5 lb 10 lb 20 lb 50 lb 100 lb

 

 2 0.71 1.41 3.54 7.07 14.1 35 70 

 4 0.50 1.00 2.50 5.00 10.0 25 50 

 6 0.41 0.82 2.04 4.08 8.2 20.4 41 

 8 0.35 0.71 1.77 3.54 7.1 17.7 35 

10 0.32 0.63 1.58 3.16 6.3 15.8 32 

12 0.29 0.58 1.44 2.89 5.8 14.4 29 

14 0.27 0.53 1.34 2.67 5.4 13.4 27 

Full electronic scales

Example: For a vehicle scale with four sections (eight load cells) and a displayed scale division of 20 lb, the maximum 

value permitted for each load cell is 7.1 lb. The calculation is shown below. If the value marked on the load cell is less 

than or equal to the value computed for the vmin, then the load cell is considered to comply with T.N.8.1.3. 

vmin ≤ d = 20 lb = 20 lb = 7.07 lb ~ 7.1 lb 

/N /8 2.83 

Mechanical Scales with single load cell

Example: Calculate the multiple of the lever system from the ratios marked on the levers. Suppose the multiple for a 

vehicle scale is 400:1 and that the scale has a scale division of 20 lb. Then the maximum value for the vmin of the load 

cell is 0.05 lb. The calculation is shown below. If the load cell is marked with a vmin less than or equal to the calculated 

value, then the load cell is considered to comply with T.N.8.1.3. 

vmin ≤ d = 20 lb = 0.05 lb 

scale multiple 400 
Vehicle and Axle-Load Scales Equipped with Electronic Digital Indicators 

EPO No. 13E 

Rev. 3/02 13E- 11

Appendix B to EPO No. 13E 

Strain-Load Method of Testing

 (Excerpts from NBS Handbook 94) 

Description of Test. When the supply of test weights is inadequate, the principle involved in the use of strain loads is 

that the known test load is first applied when the scale is carrying no other load (this is frequently referred to as the "light 

test"), and is subsequently applied one or more times when the scale is under some additional but unknown load that 

stresses the parts as they are normally stressed under ordinary operating conditions. Under this method, the actual values 

of the strain loads - which may consist of miscellaneous material, loaded vehicles, grain in a hopper, and the like - are 

immaterial and are not determined, the strain loads being simply "balanced out" by any convenient means. (The regular 

balancing means of the scale could be utilized when arriving at the final balance for a strain load, but this has the 

disadvantage that the scale cannot then be checked at the conclusion of the test for a possible shift of its zero-load 

balance; for this reason, use of the regular balancing means is not recommended here.) Thus, after carrying the light test 

of a motor-truck scale, for instance, as far as may be done with the test weights available, and assuming that it is next 

desired to make a test in the region up to one-half the nominal scale capacity, the test weights would be removed and a 

vehicle would be driven onto the platform and the scale brought to a balance; this vehicle would have been so selected 

that the sum of its gross weight and the total value of the test weights would approximate one-half the nominal capacity 

of the scale. The test weights would then be added, in one or in several increments, and it would be observed whether or 

not the scale properly indicated the value of each increment of test weights added. Following this, another strain load 

would be added, of such a value that the combined weight of the strain load and test weights would approximate the 

value in the region of which it is desired to make the next test; this strain load would then be balanced out and the test 

weights subsequently added as in the earlier part of the test. This operation may be repeated any desired number of times 

as long as the gross load does not exceed the weighing capacity of the scale; however, assuming that a reasonably 

satisfactory amount of test weights is available, not more than two strain loads will ordinarily be utilized, the scale being 

tested light and when loaded to approximately one-half and full capacities. 

Tolerance Application on Strain-Load Tests. In the strain-load method, observed errors are errors on the "testweight load only," since before each application of the test weight load the strain load of unknown value has been 

balanced out; accordingly, the tolerances to be applied are to be selected according to the value of the "test-weight 

load" in each instance of an accuracy observation under the strain-load method. 
Retail Motor-Fuel Dispensers Single, Dual and Multi-Product

EPO No. 21

Rev. 3/02 21-1

 

Examination Procedure Outline for

Retail Motor-Fuel Dispensers

Single, Dual and Multi-Product 

(Except Blenders)

It is recommended that this outline be followed for conventional, single and dual product, power-operated retail 

dispensers--"gasoline pumps," analog or digital, and consoles. This outline may also be used for multi-product dispensers 

that share a single hose but not including those that dispense blended products. Nonretroactive requirements are followed 

by the applicable date in parentheses. 

SAFETY NOTES 

When excerpting this Examination Procedure Outline for duplication, the "Safety Considerations" section and the 

"Glossary of Safety Key Phrases" should be duplicated and included with the outline. 

The inspector is reminded of the importance of evaluating potential safety hazards prior to an inspection and taking 

adequate precautions to avoid personal injury or damage to the device. The inspector should read and be familiar with the 

introductory section on safety found at the beginning of this publication. As a minimum, the following safety precautions 

should be noted and followed during the inspection. Definitions of each reminder are found in the "Glossary of Safety Key 

Phrases" at the back of this publication. 

Safety policies and regulations vary among jurisdictions. It is essential that inspectors or servicepersons be aware 

of all safety regulations and policies in place at the inspection site and to practice their employer’s safety policies. 

The safety reminders included in this EPO contain general guidelines useful in alerting inspectors and 

servicepersons to the importance of taking adequate precautions to avoid personal injury. These guidelines can only 

be effective in improving safety when coupled with training in hazard recognition and control.

 Clothing Material Safety Data Sheets (MSDS) 

 

 Electrical Hazards Nature of Product 

 Emergency Procedures Personal Protection Equipment 

 e.g., Safety Shoes, Safety Aprons, Gloves,

 Eye Protection Barrier Cream, etc. if deemed necessary

 

 Fire Extinguisher Safety Cones/Warning Signs 

 First Aid Kit Static Discharge 

 Grounding Switch Loading 

 Ignition Sources Traffic 

 Lifting Transportation of Equipment 

 Location 

 also: Wet/Slick Conditions, Chemicals, Hazardous Materials, 

 Petroleum Products, Obstructions 
Retail Motor-Fuel Dispensers Single, Dual and Multi-Product

EPO No. 21

Rev. 3/02 21-2

Inspection:

Safety First !!! 

Check the inspection site carefully for safety hazards and take appropriate precautions. 

Learn the nature of hazardous products used at or near the inspection site – obtain and read Copies of MSDS’s. 

Know emergency procedures and location and operation of fire extinguisher and emergency shut-offs.

Post safety cones/warning signs and be aware of vehicular and pedestrian traffic patterns. 

Use caution in moving in wet, slippery areas. 

Use personal protection equipment and clothing appropriate for the inspection site. 

Open both sides of dispenser to allow fumes to dissipate before proceeding with the inspection of the dispenser. 

If leaks, spills, or exposed wiring cause hazardous testing conditions it is recommended that the testing be 

discontinued until the unsafe conditions are corrected. 

Be sure that a first aid kit is available and that it is appropriate for the type of inspection activity. 

 

 H-44 General Code and 

 Liquid-Measuring Devices 

 Code References 

1. General considerations 

 Selection....................................................................................................................... G-S.3., G-UR.1.1., G-UR.1.2., 

G-UR.1.3. 

 Installation.................................................................................................................... G-S.2.,G-UR.2.1.,G-UR.2.2., 

UR.2.1., UR.2.4. 

 Position of equipment.................................................................................................. G-UR.3.3. 

 Accessibility................................................................................................................. G-UR.2.3. 

 Assistance..................................................................................................................... G-UR.4.4. 

 Use and maintenance................................................................................................... G-UR.3.1., G-UR.4.1., G-UR.4.2., 

UR.3.5. 

2. Indicating and recording elements. 

 Design........................................................................................................................... S.1.1. 

 Units ............................................................................................................................. S.1.2.1., S.1.2.3.(a) 

 Readability ................................................................................................................... G-S.5., G-S.6.(1/1/77), G-S.7., 

S.1.4., S.1.5. 

 Values of intervals ....................................................................................................... G-S.5.3., G-S.5.3.1. 

 Indication of delivery................................................................................................... S.1.6.1., 

 Money-value divisions 

 Analog.................................................................................................................... S.1.6.5.1. 

 Digital..................................................................................................................... S.1.6.5.2. 

 Auxiliary indications ............................................................................................. S.1.6.5.3. (1/1/85) 

 Unit Price and product identity ................................................................................... S.1.6.4.1.(a), S.1.6.4.2., UR.3.2. 

 Multiple unit price dispensers ..................................................................................... S.1.6.4.1.(b) (1/1/91), S.1.6.5.(a) 

(1/1/91), S.1.6.5.4. (1/1/91), 

UR.3.3. 
Retail Motor-Fuel Dispensers Single, Dual and Multi-Product

EPO No. 21

Rev. 3/02 21-3

Inspection (cont.):

 Advancement and return to zero ...............................................................................S.1.3., S.1.6.3., UR.3.1. 

 Recorded representations, point of sale systems ......................................................S.1.6.7. (1/1/86) 

 Provision for sealing..................................................................................................G-S.8. (1/1/90), G-UR.4.5., 

S.2.2.(a&b), S.2.2.(c) (1/1/5) 

3. Marking.................................................................................................................................. G-S.1.,G-UR.2.1.1.,G-UR.3.4., 

S.4.1., S.4.4. (1/1/85) 

 

4. Measuring elements. 

 Air eliminator vent, if self-contained dispenser...........................................................S.2.1. 

 Security seal on adjusting mechanism.........................................................................G-UR.4.5. 

5. Discharge hose-retail ...........................................................................................................S.3.1., S.3.2., S.3.3., S.3.5.(b), 

S.3.6., UR.1.1. 

 Marinas and Airports....................................................................................................UR.1.1.2. 

6. Totalizers ..............................................................................................................................S.5. (1/1/95) 

Pretest Determinations:

1. Tolerances. 

 Applicable requirements..................................................................................................G-T., T.1. 

 Basic values......................................................................................................................T.2.1. 

2. Product storage identification..............................................................................................UR.2.5. 

Test Notes: 

Wear appropriate personal protection equipment such as

petroleum-resistant, nonskid safety shoes (to prevent 

possible injury from spills or slipping on slick 

surfaces), protective clothing, and eye protection to 

prevent injury from splashed product. 

Do not leave an activated dispenser unattended ! 

 

1. If test measure is dry, add 16.4 milliliter (one cubic inch) to gauge reading to allow for 

 amount of liquid required to "wet" measure. 

2. Hand held test measures require a 30-second (+ 5 s) pour followed by a 10-second 

 drain, with the measure held at a (10 to 15) degree angle from vertical. 

 (see NIST HB 105-3, Specifications and Tolerances for Graduated Neck Type 

 Volumetric Field Standards, 1997, Section 7). 
Retail Motor-Fuel Dispensers Single, Dual and Multi-Product

EPO No. 21

Rev. 3/02 21-4

Test Notes (cont.):

Ground test measure properly and only use a 

metal funnel when returning product to storage.

 

3. To determine proper operation of totalizers, read and record the totalizer 

 indications before and after all test drafts............................................................................S.5. (1/1/95) 

4. After each test draft: 

 a. print ticket if device is so equipped........................................................................G-S.5.6., S.1.6.7. (1/1/86), 

UR.3.4. 

 b. check price computations on all indicators 

 (including consoles) and on recorded representations............................................S.1.6.5.(a) (1/1/91) 

 digital equipment..................................................................................................G-S.5.5. 

 analog equipment .................................................................................................S.1.6.5.(b), N.4.3.2. 

 c. check for agreement between indicators...................................................................G-S.5.2.2., S.1.6.6.(a), 

S.1.6.6.(b) (1/1/88) 

 d. check display of quantity and total price .................................................................S.1.6.5.5. (1/1/94) 

 

Test: 

Use proper lifting techniques when lifting test measure !

Be aware of and attempt to eliminate potential 

ignition sources in or near the inspection site. 

Be aware of vehicular and pedestrian traffic when 

moving between dispenser and storage tanks. 

 

1. Normal test--full flow, basic tolerance................................................................................N.1.1., N.2., N.3.4., N.4.1., 

T.2.1., UR.2.2. 

 At the beginning of the first delivery, check for suppressed values...................................S.1.6.1. 

 If first test result is at or near the tolerance limit, repeat this test. ......................................T.2.1.3., N.4.1.2. 

 Petroleum Product Sampling1

 

1 When taking gasoline samples from single hose multi-product dispensers, the samples should be collected after an 

observed sale of the particular grade or product to be tested, or sufficient product should be purged from the hose to 

ensure the sample is representative of the grade or product being sampled. The National Conference on Weights and 

Measures policy on procedures for taking samples for octane verification is as follows: “A minimum of a liter (0.3 

gallon) of engine fuel shall be flushed from the dispensers before taking a sample for octane verification. This 

flush shall be returned to the storage tank containing the lowest octane.” (see NCWM Publication 21, Petroleum 

Products Sampling Procedures and Safety Manual, August 1997). 
Retail Motor-Fuel Dispensers Single, Dual and Multi-Product

EPO No. 21

Rev. 3/02 21-5

Test (cont.):

2. Special test--slow flow, basic tolerance ..............................................................................N.4.2., N.4.2.2., T.2.1. 

3. RFI/EMI test (electronic equipment only) .........................................................................G-N.2., G-UR.1.2., 

 G-UR.3.2., G-UR.4.2. 

 Radio Frequency Interference (RFI) 

 Electromagnetic Interference (EMI) 

 

4. Check effectiveness of anti-drain means.............................................................................S.3.7.

5. Check effectiveness of zero-setback interlock....................................................................S.2.5. 

 On equipment with remote pumping systems, activate one dispenser and check all 

 others operated by the same pump to make certain they will not operate without 

 activating the individual starting levers. 

6. Power loss test......................................................................................................................S.1.6.2.1.(1/1/83), S.1.6.2.2. 

(1/1/83) 

 Check with your supervisor before requiring shutdown of power to equipment 

 under test. 

7. Security seal .........................................................................................................................G-UR.4.5. 

Record on the official report the number of gallons of product dispensed during test. 

Avoid switch loading! 

Test devices dispensing low-vapor pressure products (e.g., diesel fuel, kerosene) 

before testing devices dispensing high-vapor pressure products (e.g., gasoline).

 

After all equipment at a location has been tested, review results to determine compliance 

with equipment maintenance and use of adjustments ................................................................G-UR.4.1., G-UR.4.3. 

Take precautions to isolate equipment when 

transporting it to avoid exposure to hazardous fumes.
Retail Motor-Fuel Dispensers Blended Products 

EPO No. 22

Rev. 3/02 22-1

Examination Procedure Outline for

Retail Motor-Fuel Dispensers

Blended Product

It is recommended that this outline be followed for blending-type, power-operated retail dispensers--"gasoline pumps," 

analog or digital, and consoles. Nonretroactive requirements are followed by the applicable date in parentheses. 

SAFETY NOTES 

When excerpting this Examination Procedure Outline for duplication, the "Safety Considerations" section and the 

"Glossary of Safety Key Phrases" should be duplicated and included with the outline. 

The inspector is reminded of the importance of evaluating potential safety hazards prior to an inspection and taking 

adequate precautions to avoid personal injury or damage to the device. The inspector should read and be familiar with 

the introductory section on safety found at the beginning of this publication. As a minimum, the following safety 

precautions should be noted and followed during the inspection. Definitions of each reminder are found in the 

"Glossary of Safety Key Phrases" at the back of this publication. 

Safety policies and regulations vary among jurisdictions. It is essential that inspectors or servicepersons be 

aware of all safety regulations and policies in place at the inspection site and to practice their employer’s safety 

policies. The safety reminders included in this EPO contain general guidelines useful in alerting inspectors and 

servicepersons to the importance of taking adequate precautions to avoid personal injury. These guidelines can 

only be effective in improving safety when coupled with training in hazard recognition and control.

 Clothing Material Safety Data Sheets (MSDS) 

 

 Electrical Hazards Nature of Product 

 Emergency Procedures Personal Protection Equipment 

 e.g., Safety Shoes, Safety Aprons, Gloves,

 Eye Protection Barrier Cream, etc. if deemed necessary

 

 Fire Extinguisher Safety Cones/Warning Signs 

 First Aid Kit Static Discharge 

 Grounding Switch Loading 

 Ignition Sources Traffic 

 Lifting Transportation of Equipment 

 Location 

 also: Wet/Slick Conditions, Chemicals, Hazardous Materials, 

 Petroleum Products, Obstructions 
Retail Motor-Fuel Dispensers Blended Products 

EPO No. 22

Rev. 3/02 22-2

Inspection:

Safety First !!! 

Check the inspection site carefully for safety hazards and take appropriate precautions. 

Learn the nature of hazardous products used at or near the inspection site – obtain and read copies of MSDS’s. 

Know emergency procedures and location and operation of fire extinguisher and emergency shut-offs.

Post safety cones/warning signs and be aware of vehicular and pedestrian traffic patterns. 

Use caution in moving in wet, slippery areas. 

Use personal protection equipment and clothing appropriate for the inspection site. 

Open both sides of dispenser to allow fumes to dissipate before proceeding with the inspection of the dispenser. 

If leaks, spills, or exposed wiring cause hazardous testing conditions it is recommended that the testing be 

discontinued until the unsafe conditions are corrected. 

Be sure that a first aid kit is available and that it is appropriate for the type of inspection activity. 

 

 

 H-44 General Code and 

 Liquid-Measuring Devices 

 Code References

1. General considerations. 

 Selection...........................................................................................................................G-S.3., G-UR.1.1., GUR.1.2., G-UR.1.3. 

 Installation........................................................................................................................G.S.2, G-UR.2.1., 

G-UR.2.2., UR.2.1., 

UR.2.4. 

 Position of equipment ......................................................................................................G-UR.3.3. 

 Accessibility.....................................................................................................................G-UR.2.3. 

 Assistance.........................................................................................................................G-UR.4.4. 

 Use and maintenance .......................................................................................................G-UR.3.1., G-UR.4.1., 

 G-UR.4.2., UR.3.5. 

2. Indicating and recording elements. 

 Design...........................................................................................................................S.1.1. 

 Units..............................................................................................................................S.1.2.1., S.1.2.3.(a) 

 Readability....................................................................................................................G-S.5., G-S.6. (1/1/77), 

G-S.7., S.1.4., S.1.5. 

 Values of intervals........................................................................................................G-S.5.3., G-S.5.3.1. 

 Indication of delivery ...................................................................................................S.1.6.1. 

 Money-value divisions 

 Analog .......................................................................................................................S.1.6.5.1. 

 Digital ........................................................................................................................S.1.6.5.2. 

 Auxiliary indications .................................................................................................S.1.6.5.3. (1/1/85) 

 Unit Price and product identity ....................................................................................S.1.6.4.1.(a), S.1.6.4.2., 

U.R.3.2. 
Retail Motor-Fuel Dispensers Blended Products 

EPO No. 22

Rev. 3/02 22-3

 

Inspection (cont.):

 

 Multiple unit price dispensers ......................................................................................S.1.6.4.1.(b) (1/1/91), 

S.1.6.5.(a) (1/1/91), 

S.1.6.5.4. (1/1/91), UR.3.3. 

 Advancement and return to zero ..................................................................................S.1.3., S.1.6.3., UR.3.1. 

 Recorded representations, point of sale systems .........................................................S.1.6.7. (1/1/86) 

 Provision for sealing.....................................................................................................G-S.8.(1/1/90), G-UR.4.5., 

S.2.2.(a&b), S.2.2.(c) 

(1/1/95) 

3. Marking................................................................................................................................G-S.1., G-UR.2.1.1., 

G-UR.3.4., S.4.1., S.4.4. 

(1/1/85) 

 

4. Measuring elements. 

 Air eliminator vent, if self-contained dispenser...........................................................S.2.1. 

 Security seal on adjusting mechanism.........................................................................G-UR.4.5. 

5. Discharge hose-retail ...........................................................................................................S.3.1., S.3.2., S.3.3., S.3.5., 

S.3.6., UR.1.1. 

 Marinas and airports.....................................................................................................UR.1.1.2. 

6. Totalizers ..............................................................................................................................S.5. (1/1/95) 

Pretest Determinations:

1. Tolerances. 

 Applicable requirements ..............................................................................................G-T., T.1. 

 Basic tolerance values ..................................................................................................T.2.1. 

2. Product storage identification..............................................................................................UR.2.5. 

Test Notes: 

Wear appropriate personal protection equipment such as

petroleum-resistant, nonskid safety shoes (to prevent 

possible injury from spills or slipping on slick 

surfaces), protective clothing, and eye protection to 

prevent injury from splashed product. 

Do not leave an activated dispenser unattended ! 

 

1. If test measure is dry, add 16.4 milliliters (one cubic inch) to gauge reading to allow for amount 

 of liquid required to "wet" measure. 

2. Hand held test measures require a 30-second (+ 5 s) pour followed by a 10-second 

 drain, with the measure held at a (10 to 15) degree angle from vertical. 
Retail Motor-Fuel Dispensers Blended Products 

EPO No. 22

Rev. 3/02 22-4

Test Notes (cont.):

 (see NIST HB 105-3, Specifications and Tolerances for Graduated Neck Type Volumetric Field Standards, 1997, 

section 7). 

Ground test measure properly and only use a 

metal funnel when returning product to storage.

3. To determine proper operation of totalizers, read and record the totalizer indications 

 before and after all test drafts. .............................................................................................S.5. (1/1/95) 

4. After each test draft: 

 a. print ticket if device is so equipped..............................................................................G-S.5.6., S.1.6.7. (1/1/86), 

UR.3.4. 

b. check price computations on all indicators..................................................................S.1.6.5.(a) (1/1/91) 

(including consoles) and on recorded representations. 

 digital equipment.......................................................................................................G-S.5.5. 

 analog equipment ......................................................................................................S.1.6.5.(b), N.4.3.2. 

 c. check for agreement between indications...............................................................G-S.5.2.2., S.1.6.6.(a), 

S.1.6.6.(b) (1/1/88) 

 d. check display of quantity and total price .....................................................................S.1.6.5.5. (1/1/94) 

 

Test: 

Use proper lifting techniques when lifting test measure !

Be aware of and attempt to eliminate potential 

ignition sources in or near the inspection site. 

Be aware of vehicular and pedestrian traffic when 

moving between dispenser and storage tanks. 

 

1. Test at lowest grade. Set selector control so that lowest grade product is dispensed. 

 Normal test—full flow, basic tolerance ..............................................................................N.1.1., N.2., N.3.4., N.4.1., 

T.2.1., UR.2.2. 

 At the beginning of the first delivery, check for suppressed values...................................S.1.6.1. 

 If first test result is at or near the tolerance limit, repeat this test. ......................................T.2.1.3., N.4.1.2. 

 Petroleum Product Sampling1

 Lowest Octane. 

 

1

 When taking gasoline samples from blended product dispensers, the samples should be collected after an observed sale of the 

particular grade or product to be tested, or sufficient product should be purged from the hose to ensure the sample is 

representative of the grade or product being sampled. The National Conference on Weights and Measures policy on procedures 

for taking samples for octane verification is as follows: “A minimum of a liter (0.3 gallon) of engine fuel shall be flushed 

from the dispensers before taking a sample for octane verification. This flush shall be returned to the storage tank 

containing the lowest octane.” (see NCWM Publication 21, Petroleum Products Sampling Procedures and Safety Manual,

August 1997). 
Retail Motor-Fuel Dispensers Blended Products 

EPO No. 22

Rev. 3/02 22-5

Test (cont.):

2. Test at highest grade. Set selector control so that highest grade product is dispensed. 

 Normal test—full flow, basic tolerance ..............................................................................N.3.4., N.4.1., T.2.1. 

 If this test is at or near tolerance limit, repeat this test........................................................T.2.1.3. 

 

 Petroleum Product Sampling2

 Highest Octane 

3. Test at blend. Set selector control at intermediate blend. Special test--slow flow, basic 

 Tolerance..............................................................................................................................N.4.2., N.4.2.2., T.2.1. 

 If this test result is at or near the tolerance limit and the error is the same as or greater 

 then the average error of the previous tests, repeat this test................................................T.2.1.3. 

 Otherwise, slow flow test at first blend above lowest grade and first blend beneath 

 highest grade. 

 Petroleum Product Sampling2

 Blended Product 

 

Return blended product to the storage tank containing the lowest octane 

4. Check money-value computations on other blends. Set selector control at each of the 

remaining blends and dispense 1 indicated liter/gallon to check computed price .............UR.3.2. 

 Digital equipment.........................................................................................................G-S.5.5. 

 Analog equipment ........................................................................................................S.1.6.5.(b), N.4.3.2. 

5. RFI/EMI test (electronic equipment only) ..........................................................................G-N.2., G-UR.1.2., 

 G-UR.3.2., G-UR.4.2. 

 Radio Frequency Interference (RFI) 

 Electromagnetic Interference (EMI) 

 

6. Check effectiveness of anti-drain means.............................................................................S.3.7.

7. Check effectiveness of zero-setback interlock....................................................................S.2.5. 

 On equipment with remote pumping systems, activate one dispenser and check all 

 others operated by the same pump to make certain they will not operate without 

 activating the individual starting levers. 

8. Power loss test......................................................................................................................S.1.6.2.1.(1/1/83), 

S.1.6.2.2. (1/1/83) 

 Check with your supervisor before requiring shutdown of power to equipment under test. 

9. Security seal .........................................................................................................................G-UR.4.5. 

Record on the official report the number of gallons of product dispensed during test. 

 

2 When taking gasoline samples from blended product dispensers, the samples should be collected after an observed sale of the 

particular grade or product to be tested, or sufficient product should be purged from the hose to ensure the sample is 

representative of the grade or product being sampled. The National Conference on Weights and Measures policy on procedures 

for taking samples for octane verification is as follows: “A minimum of a liter (0.3 gallon) of engine fuel shall be flushed 

from the dispensers before taking a sample for octane verification. This flush shall be returned to the storage tank 

containing the lowest octane.” (see NCWM Publication 21, Petroleum Products Sampling Procedures and Safety Manual, 

August 1997).
Retail Motor-Fuel Dispensers Blended Products 

EPO No. 22

Rev. 3/02 22-6

Test (cont.):

Avoid switch loading! 

Test devices dispensing low-vapor pressure products (e.g., diesel fuel, kerosene) 

before testing devices dispensing high-vapor pressure products (e.g., gasoline).

 

After all equipment at a location has been tested, review results to determine compliance with 

equipment maintenance and use of adjustments.........................................................................G-UR.4.1., G-UR.4.3. 

Take precautions to isolate equipment when 

transporting it to avoid exposure to hazardous fumes.
Vehicle-Tank Meters Power-Operated

EPO No. 23

Rev. 3/02 23-1

Examination Procedure Outline for

Vehicle-Tank Meters 

Power-Operated

It is recommended that this outline be followed for all power-operated vehicle-tank meters – analog or digital. 

Nonretroactive requirements are followed by the applicable date in parentheses. Do not use this outline for testing milk 

metering systems, or gravity-discharge vehicle tank meters. 

SAFETY NOTES 

When excerpting this Examination Procedure Outline for duplication, the "Safety Considerations" section and the 

"Glossary of Safety Key Phrases" should be duplicated and included with the outline. 

The inspector is reminded of the importance of evaluating potential safety hazards prior to an inspection and taking 

adequate precautions to avoid personal injury or damage to the device. The inspector should read and be familiar with 

the introductory section on safety found at the beginning of this publication. As a minimum, the following safety 

precautions should be noted and followed during the inspection. Definitions of each reminder are found in the 

"Glossary of Safety Key Phrases" at the back of this publication. 

Safety policies and regulations vary among jurisdictions. It is essential that inspectors or servicepersons be 

aware of all safety regulations and policies in place at the inspection site and to practice their employer’s safety 

policies. The safety reminders included in this EPO contain general guidelines useful in alerting inspectors and 

servicepersons to the importance of taking adequate precautions to avoid personal injury. These guidelines can 

only be effective in improving safety when coupled with training in hazard recognition and control.

 Clothing Material Safety Data Sheets (MSDS) 

 

 Electrical Hazards Nature of Product 

 Emergency Procedures Personal Protection Equipment 

 e.g., Safety Shoes, Safety Aprons, Gloves,

 Eye Protection Hard Hat, etc. if deemed necessary

 

 Fire Extinguisher Safety Cones/Warning Signs 

 First Aid Kit Static Discharge 

 Grounding Switch Loading 

 Ignition Sources Traffic 

 Lifting Transportation of Equipment 

 Location 

 

 also: Wet/Slick Conditions, Chemicals, Hazardous Materials, 

 Petroleum Products, Obstructions 
Vehicle-Tank Meters Power-Operated

EPO No. 23

Rev. 3/02 23-2

Inspection:

Safety First !!! 

Check the inspection site carefully for safety hazards and take appropriate precautions. 

Check to be certain that the ground surface of the inspection site is sufficiently strong and rigid to support the 

prover when it is filled with product – don’t forget to chock the wheels of the prover. 

Learn the nature of hazardous products used at or near the inspection site – obtain and read copies of MSDS’s. 

Know emergency procedures and location and operation of fire extinguisher and emergency shut-offs.

Post safety cones/warning signs and be aware of vehicular and pedestrian traffic patterns. 

Use caution in moving in wet, slippery areas and climbing on prover, storage tanks, and vehicles. 

Use personal protection equipment and clothing appropriate for the inspection site. 

If leaks, spills, or exposed wiring cause hazardous testing conditions it is recommended that the testing be 

discontinued until the unsafe conditions are corrected. 

Be sure that a first aid kit is available and that it is appropriate for the type of inspection activity. 

 

 H-44 General Code and 

 Vehicle-Tank Meters 

 Code References

1. General considerations. 

 Selection .......................................................................................................................G-S.3., G-UR.1.1., GUR.1.2., G-UR.1.3. 

 Installation ....................................................................................................................G-S.2., G-UR.2.1., 

G-UR.2.2., UR.1.1. 

 Position of equipment...................................................................................................G-UR.3.3. 

 Accessibility .................................................................................................................G-UR.2.3. 

 Assistance .....................................................................................................................G-UR.4.4., G-UR.4.6 

 Use and maintenance....................................................................................................G-UR.3.1., G-UR.4.1., GUR.4.2., UR.2.3. 

2. Indicating and recording elements. 

 Design...........................................................................................................................S.1.1.1. 

 Units ..............................................................................................................................S.1.1.2.(a), S.1.1.3.(b) and 

(c) 

 Readability....................................................................................................................G-S.5., G-S.6. (1/1/77), 

G-S.7., S.1.2., S.1.3. 

 Values of intervals........................................................................................................G-S.5.3. 

 Computing-type devices 

 Display of unit price..................................................................................................S.1.4.1, UR.1.2. 

 Printed ticket..............................................................................................................S.1.4.2., UR.2.2. 

 Exceptions for the sale of aviation fuel.....................................................................UR.2.2.1. 

 Money-value computations.......................................................................................S.1.4.3. 

 Advancement and return to zero ..................................................................................S.1.1.4., S.1.1.5., UR.2.1. 

 Provision for sealing.....................................................................................................G-S.8. (1/1/90), G-UR.4.5. 
Vehicle-Tank Meters Power-Operated

EPO No. 23

Rev. 3/02 23-3

Inspection (cont.):

3. Marking................................................................................................................................G-S.1., G-UR.2.1.1., 

S.5.1, S.5.2. 

 

4. Measuring elements. 

 Vapor elimination.........................................................................................................S.2.1. 

 Security seal on adjusting mechanism.........................................................................G-UR.4.5., S.2.2. 

5. Piping. 

 Directional flow valves and discharge line and valves................................................S.2.3., S.3. 

 Antidrain valve .............................................................................................................S.3.6. 

 Leaks.............................................................................................................................G-UR.4.1. 

 Facilitation of fraud......................................................................................................G-S.2. 

Pretest Determinations: 

1. Determine that the test fluid in the tank compartment is similar in character to the fluid 

 to be measured........................................................................................................................ N.1. 

2. Test drafts: determine if the prover size is adequate............................................................. N.3. 

3. Tolerances. 

 Applicable requirements ..............................................................................................G-T., T.1. 

 Tolerance values...........................................................................................................T.2. 

 Agri-chemicals .............................................................................................................T.3. 

 Repeatability.................................................................................................................T.4. 

4. Note totalizer reading 

Test Notes:

Wear appropriate personal protection equipment such as petroleum-resistant, nonskid safety shoes (to prevent 

possible injury from spills or slipping on slick surfaces), protective clothing, eye protection (to prevent injury 

from splashed product), and a hard hat (to prevent injuryfrom overhangs and projections). 

Use proper grounding procedures. 

Be sure that prover is equipped with an explosion proof motor. 

Carefully inspect electrical supply lines to test equipment for wear and damage; correct potentially hazardous 

conditions before use. 

Device operator should be present at all times during test – the operator (not the inspector) should operate the 

device under test. 

Never leave equipment unattended while it is in operation. 

1. Wet prover. Allow a 30-second drain period each time the prover is emptied. 

2. Evaporation and volume change: exercise care so the product temperature 

 is the same in the prover as at the meter..............................................................................N.2. 
Vehicle-Tank Meters Power-Operated

EPO No. 23

Rev. 3/02 23-4

 

Test Notes (cont.):

3. Record totalizer(s) indication before and after each draft to determine proper operation 

4. After each test draft: 

 a. Print a ticket (if so equipped).......................................................................................G-S.5.6. 

b. If computing type, check price computation on indicator and on recorded 

 representations........................................................................................................G.S.5.6., S.1.4.2., S.1.4.3., 

S.1.4.4. 

 c. Check for agreement between indicators.....................................................................G-S.5.2.2. 

 

Test: 

If supply or return lines are not coupled at their discharge ends, they must be 

 held in place continuously while product flows through the line 

Use proper lifting techniques to lift and move equipment 

Be aware of and attempt to eliminate potential ignition sources in or near the 

inspection site 

Be aware of vehicular and pedestrian traffic in the area 

 

1. Normal test--full flow, basic tolerance................................................................................N.4.1., T.2. 

2. Special test--slow flow, special tolerance ...........................................................................N.4.2.(a), T.2. 

 If either test result is close to or outside the applicable tolerance, repeat the test..........N.4.1.2. 

3. Special test – split compartment, special tolerance.............................................................S.2.1., N.4.2.(b), T.2. 

a. Start test (normal flow rate) from a compartment containing less test fluid than 

 one-half the capacity of the prover and with pump in operation and pressure 

 to the discharge nozzle. 

b. Permit test to continue until lack of fluid supply causes meter register to stop absolutely. 

c. With pump in operation, shut manifold valve (or disconnect whip-hose connection) 

 from now empty compartment. 

d. Open valve from compartment with adequate supply of fluid to complete test. 

4. RFI/EMI test (electronic equipment only).....................................................................G-N.2., G-UR.1.2., 

G-UR.3.2., G-UR.4.2. 

 Radio Frequency Interference (RFI) 

 Electromagnetic Interference (EMI) 

5. Check automatic stop mechanism. ......................................................................................G-UR.4.1. 

 The device should stop the flow within one-half the minimum interval indicated 

6. Check effectiveness of antidrain valve................................................................................S.3.6., N.4.3. 

 (with pump pressure off line) 
Vehicle-Tank Meters Power-Operated

EPO No. 23

Rev. 3/02 23-5

Test (cont.):

7. Security seal .........................................................................................................................G-UR.4.5. 

Record the number of gallons of product dispensed during test on the official report. 

Avoid switch loading! 

Test devices dispensing low-vapor pressure products (e.g., diesel fuel, kerosene) 

before testing devices dispensing high-vapor pressure products (e.g., gasoline). 

 

After all equipment at a location has been tested, review results to determine compliance 

with equipment maintenance and use of adjustments ................................................................G-UR.4.1., G-UR.4.3. 

Take precautions to isolate equipment when 

Transporting it to avoid exposure to hazardous fumes.
Vehicle-Tank Meters Gravity-Discharge

EPO No. 24

Rev. 3/02 24-1

 

Examination Procedure Outline for

Vehicle-Tank Meters 

Gravity-Discharge

It is recommended that this outline be followed for all gravity-discharge vehicle-tank meters – analog or digital. 

Nonretroactive requirements are followed by the applicable date in parentheses. Do not use this outline for testing milk 

metering systems, or power-operated vehicle tank meters. 

SAFETY NOTES 

When excerpting this Examination Procedure Outline for duplication, the "Safety Considerations" section and the 

"Glossary of Safety Key Phrases" should be duplicated and included with the outline. 

The inspector is reminded of the importance of evaluating potential safety hazards prior to an inspection and taking 

adequate precautions to avoid personal injury or damage to the device. The inspector should read and be familiar with 

the introductory section on safety found at the beginning of this publication. As a minimum, the following safety 

precautions should be noted and followed during the inspection. Definitions of each reminder are found in the 

"Glossary of Safety Key Phrases" at the back of this publication. 

Safety policies and regulations vary among jurisdictions. It is essential that inspectors or servicepersons be 

aware of all safety regulations and policies in place at the inspection site and to practice their employer’s safety 

policies. The safety reminders included in this EPO contain general guidelines useful in alerting inspectors and 

servicepersons to the importance of taking adequate precautions to avoid personal injury. These guidelines can 

only be effective in improving safety when coupled with training in hazard recognition and control.

 Clothing Material Safety Data Sheets (MSDS) 

 

 Electrical Hazards Nature of Product 

 Emergency Procedures Personal Protection Equipment 

 e.g., Safety Shoes, Safety Aprons, Gloves,

 Eye Protection Hard Hat, etc. if deemed necessary

 

 Fire Extinguisher Safety Cones/Warning Signs 

 First Aid Kit Static Discharge 

 Grounding Switch Loading 

 Ignition Sources Traffic 

 Lifting Transportation of Equipment 

 Location 

 

 also: Wet/Slick Conditions, Chemicals, Hazardous Materials, 

 Petroleum Products, Obstructions 
Vehicle-Tank Meters Gravity-Discharge

EPO No. 24

Rev. 3/02 24-2

Inspection:

Safety First !!! 

Check the inspection site carefully for safety hazards and take appropriate precautions. 

Check to be certain that the ground surface of the inspection site is sufficiently strong and rigid to support the 

prover when it is filled with product – don’t forget to chock the wheels of the prover. 

Learn the nature of hazardous products used at or near the inspection site – obtain and read copies of MSDS’s. 

Know emergency procedures and location and operation of fire extinguisher and emergency shut-offs.

Post safety cones/warning signs and be aware of vehicular and pedestrian traffic patterns. 

Use caution in moving in wet, slippery areas and climbing on prover, storage tanks, and vehicles. 

Use personal protection equipment and clothing appropriate for the inspection site. 

If leaks, spills, or exposed wiring cause hazardous testing conditions it is recommended that the testing be 

discontinued until the unsafe conditions are corrected. 

Be sure that a first aid kit is available and that it is appropriate for the type of inspection activity. 

 

 

 H-44 General Code and 

 Vehicle-Tank Meters 

 Code References

1. General considerations. 

 Selection .......................................................................................................................G-S.3., G-UR.1.1., GUR.1.2., G-UR.1.3. 

 Installation ....................................................................................................................G-S.2., G-UR.2.1., 

G-UR.2.2., UR.1.1. 

 Position of equipment...................................................................................................G-UR.3.3. 

 Accessibility .................................................................................................................G-UR.2.3. 

 Assistance .....................................................................................................................G-UR.4.4., G-UR.4.6. 

 Use and maintenance....................................................................................................G-UR.3.1., G-UR.4.1., GUR.4.2., UR.2.3. 

2. Indicating and recording elements. 

 Design...........................................................................................................................S.1.1.1. 

 Units ..............................................................................................................................S.1.1.2.(a) , S.1.1.3.(b) and 

(c) 

 Readability....................................................................................................................G-S.5., G-S.6. (1/1/77), 

G-S.7., S.1.2., S.1.3. 

 Values of intervals........................................................................................................G-S.5.3. 

 Computing-type devices 

 Display of unit price.....................................................................................................S.1.4.1, UR.1.2. 

 Printed ticket.................................................................................................................S.1.4.2., UR.2.2. 

 Exceptions for the sale of aviation fuel ...................................................................UR.2.2.1. 

 Money-value computations .........................................................................................S.1.4.3. 

 Advancement and return to zero..........................................................................................S.1.1.4., S.1.1.5., UR.2.1. 
Vehicle-Tank Meters Gravity-Discharge

EPO No. 24

Rev. 3/02 24-3

Inspection (cont.):

 Provision for sealing ............................................................................................................G-S.8. (1/1/90), G-UR.4.5. 

3. Marking................................................................................................................................G-S.1., G-UR.2.1.1., 

S.5.1, S.5.2. 

4. Measuring elements. 

 Vapor elimination.........................................................................................................S.2.1. 

 Security seal on adjusting mechanism.........................................................................G-UR.4.5., S.2.2. 

5. Piping. 

 Directional flow valves and discharge line and valves................................................S.2.3., S.3. 

 Leaks.............................................................................................................................G-UR.4.1. 

 Facilitation of fraud......................................................................................................G-S.2. 

Pretest Determinations: 

1. Determine that the test fluid in the tank compartment is similar in character to the fluid 

 to be measured........................................................................................................................ N.1. 

2. Determine that a compartment or compartments have a sufficient amount of product to 

 conduct “high head” and “low head” tests. 

3. Test drafts: determine if the prover size is adequate and that the prover inlet is lower 

 than the meter outlet .............................................................................................................. N.3. 

4. Tolerances. 

 Applicable requirements ..............................................................................................G-T., T.1. 

 Tolerance values...........................................................................................................T.2. 

 Agri-chemicals .............................................................................................................T.3. 

 Repeatability.................................................................................................................T.4. 

5. Note totalizer reading 

Test Notes:

Wear appropriate personal protection equipment such as petroleum-resistant, nonskid safety shoes (to prevent 

possible injury from spills or slipping on slick surfaces), protective clothing, eye protection (to prevent injury 

from splashed product), and a hard hat (to prevent injury from overhangs and projections). 

Use proper grounding procedures. 

Be sure that prover is equipped with an explosion proof motor. 

Carefully inspect electrical supply lines to test equipment for wear and damage; correct potentially hazardous 

conditions before use. 

Device operator should be present at all times during test – the operator (not the inspector) should operate 

the device under test. Do not leave equipment unattended while in operation. 
Vehicle-Tank Meters Gravity-Discharge

EPO No. 24

Rev. 3/02 24-4

Test Notes (cont.):

1. Wet prover. Allow a 30-second drain period each time prover is emptied. 

2. Evaporation and volume change: exercise care so that the product temperature 

 is the same in the prover as at the meter..............................................................................N.2. 

 

3. Record totalizer (s) indication before and after each draft to determine proper operation 

4. After each test draft: 

 a. Print a ticket (if so equipped).......................................................................................G-S.5.6. 

b. If computing type, check price computation on indicator and on recorded 

 representations..............................................................................................................G.S.5.6., S.1.4.2., S.1.4.3., 

S.1.4.4. 

 c. Check for agreement between indicators.....................................................................G-S.5.2.2. 

 

Test: 

If supply or return lines are not coupled at their discharge ends, they must be 

 held in place continuously while product flows through the line. 

Use proper lifting techniques to lift and move equipment. 

Be aware of and attempt to eliminate potential ignition sources in or near the 

inspection site. 

Be aware of vehicular and pedestrian traffic in the area. 

 

1. Normal test--full flow (high head, full compartment), basic tolerance ..............................N.4.1., T.2. 

2. Normal test – full flow (medium head, one-half full compartment), basic tolerance ........N.4.1., T.2. 

3. Normal test – full flow (low head, one and one-half times prover capacity in 

 compartment), basic tolerance.............................................................................................N.4.1., T.2. 

4. Special test – split compartment, special tolerance.............................................................S.2.1., N.4.2. (b) , T.2. 

a. Start test (normal flow rate) from a compartment containing less test load than 

 one-half prover capacity. 

b. Permit test to continue until lack of fluid supply causes meter register to stop absolutely. 

c. Shut manifold valve (or disconnect whip-hose connection) from now empty compartment. 

 d. Open valve from compartment with adequate supply of fluid to complete test. 

5. RFI/EMI test (electronic equipment only).....................................................................G-N.2., G-UR.1.2., 

G-UR.3.2., G-UR.4.2. 

 Radio Frequency Interference (RFI) 

 Electromagnetic Interference (EMI) 

 

6. Check automatic stop mechanism. ......................................................................................G-UR.4.1. 

 The device should stop the flow within one-half the minimum interval indicated. 

7. Security seal .........................................................................................................................G-UR.4.5. 
Vehicle-Tank Meters Gravity-Discharge

EPO No. 24

Rev. 3/02 24-5

Test (cont.):

Record on the official report the number of gallons of product dispensed during test. 

Avoid switch loading! 

Test devices dispensing low-vapor pressure products (e.g., diesel fuel, kerosene) 

before testing devices dispensing high-vapor pressure products (e.g., gasoline). 

 

After all equipment at a location has been tested, review results to determine compliance 

with equipment maintenance and use of adjustments ................................................................G-UR.4.1., G-UR.4.3. 

Take precautions to isolate equipment when 

transporting it to avoid exposure to hazardous fumes.
Loading-Rack Meters 

EPO No. 25 

Rev 3/02 25-1 

 

Examination Procedure Outline for 

Loading-Rack Meters

It is recommended that this outline be followed for examining loading-rack meters used to measure petroleum products 

sold at wholesale. The outline may be applied to devices with or without Automatic Temperature Compensating 

Systems. Non-retroactive and retroactive requirements are followed by the applicable date in parentheses. 

SAFETY NOTES 

When excerpting this Examination Procedure Outline for duplication, the "Safety Considerations" section and the 

"Glossary of Safety Key Phrases" should be duplicated and included with the outline. 

The inspector is reminded of the importance of evaluating potential safety hazards prior to an inspection and taking 

adequate precautions to avoid personal injury or damage to the device. The inspector should read and be familiar with

the introductory section on safety found at the beginning of this publication. As a minimum, the following safety

precautions should be noted and followed during the inspection. Definitions of each reminder are found in the "Glossary

of Safety Key Phrases" at the back of this publication. 

Safety policies and regulations vary among jurisdictions. It is essential that inspectors or servicepersons be aware of

all safety regulations and policies in place at the inspection site and to practice their employer’s safety policies. The

safety reminders included in this EPO contain general guidelines useful in alerting inspectors and servicepersons to

the importance of taking adequate precautions to avoid personal injury. These guidelines can only be effective in

improving safety when coupled with training in hazard recognition and control.

 

Clothing Material Safety Data Sheets (MSDS) 

 Electrical Hazards Nature of Product 

 Emergency Procedures Personal Protection Equipment 

 e.g., Safety Shoes 

 Eye Protection Safety Aprons, Respirators, Gloves, Barrier Cream,

 Etc., if deemed necessary. 

 Fire Extinguisher Hard Hat -- for protection from overhang in rear

 of vehicle tank truck 

 First Aid Kit 

 Safety Cones/Warning Signs 

 Grounding 

 Static Discharge 

 Ignition Sources 

 Support -- for prover 

 Lifting 

 Switch Loading 

 Location 

also: Wet/Slick Conditions Obstructions and Overhead Hazards 

 Chemicals, Petroleum Products, 

 And Hazardous Materials 
Loading-Rack Meters

EPO No. 25 

Rev 3/02 25-2 

Pretest Determinations: 

Safety First !!! 

Pretest Determinations (cont.) 

H-44 General Code and 

Liquid Measuring devices

Code References

1. Prover must have valid calibration certificate and security seals must be intact on sight gauge. 

2. Prover capacity must be sufficient to hold the amount of product that would be 

 delivered by the meter to be tested during 1 minute of flow at its maximum 

 discharge rate and in no case be less than 200 liters (50 gallons) .................................N.3.5. 

3. Prover and system design must be compatible (top loading/bottom loading). 

Check the inspection site carefully for 

safety hazards and take appropriate precautions. 

Check to be certain that the ground surface of the inspection site is 

 sufficiently strong and rigid to support the prover when it is filled with product 

---don't forget to chock the wheels of the prover. 

Learn the nature of hazardous products used at or near 

the inspection site--obtain and read copies of MSD's. 

Know emergency procedures and location and operation 

of fire extinguishers and emergency shut-offs. 

Post safety cones/warning signs and be aware 

of vehicular and pedestrian traffic patterns. 

Use caution moving arund in wet, slippery areas 

and in climbing on prover, storage tanks, and vehicles. 

Use personal protection equipment and clothing 

appropriate for the inspection site. 

Be sure that a first aid kit is available and that the 

kit is appropriate for the type of inspection activity. 
Loading-Rack Meters

EPO No. 25 

Rev 3/02 25-3 

Pretest Determinations (cont.):

4. Thermometers are to be accurate to within: 

a. ± 0.5 °C, have a range of at least 0 °C to 50 °C, and be divided in increments of no greater than 0.5 °C 

for liquid-in-glass thermometers and 0.1 °C for digital thermometers or 

b. ± 1 °F, have a range of at least 0 °F to 120 °F, and be divided in increments of no greater than 1 °F for 

liquid-in-glass thermometers and 0.1 °F for digital thermometers. 

 Thermometers may be of the partial immersion or digital type. 

5. Inspect prover's interior surface for dents, product clingage, rust, water, or other 

 foreign material. 

6. Prover sight glass must be clean and fittings must not leak. 

7. Available test fluid must be of the same general physical characteristics as that of 

 the liquid to be commercially measured by the device ..................................................N.1.1. 

8. For top loading provers, the prover inlet must be lower than the outlet of the meter 

 discharge line. 

9. Determine applicable tolerance values: 

 Applicable requirements.........................................................................................G-T, T.1. 

 Basic values............................................................................................................T.2.3.3. 

 a. On normal tests: 

 Acceptance tolerance .....................................................................................0.2 percent 

 Maintenance tolerance ...................................................................................0.3 percent 

 b. On special tests: 

 Acceptance tolerance and maintenance tolerance..........................................0.5 percent 

Inspection:

1. Indicating and recording elements. 

 Design: 

 Device must be equipped with indicating elements and MAY be equipped 

 with a recording element. .......................................................................................S.1.1. 

 Units: 

 Units are to be in terms of liters, gallons, quarts, pints, or binary-sub-multiples 

 or decimal subdivisions of the liter or gallon. .......................................................S.1.2., S.1.2.3.(b) 

Be sure the prover is equipped with an explosion-proof motor. 

Carefully inspect electrical supply lines for test equipment for wear or damage; correct 

potentially hazardous conditions before use; protect lines from damage during use. 
Loading-Rack Meters

EPO No. 25 

Rev 3/02 25-4 

Inspection (cont.):

 Readability: 

 Indicating and recording elements must be clear, definite, and easily read............G-S.5., S.1.4., S.1.5. 

 Required markings shall be distinct, easily readable, and of a permanent 

 nature......................................................................................................................G-S.6.(1/1/77), G-S.7. 

Values of intervals: 

 Values of the graduated intervals must be uniform throughout the series of 

 indicating elements or, if equipped, recording elements. .......................................G-S.5.3. 

 For devices indicating or recording in more than one unit, the values must be 

 appropriately identified. .........................................................................................G-S.5.3.1. (1/1/90) 

 Advancement and return to zero:...................................................................................S.1.3. 

 Indicating and recording elements may only be advanced to zero by the 

 mechanical operation of the device, UNLESS: 

 a. Advancement can not be stopped until zero is reached, OR 

 b. The indicating elements are automatically obscured until the elements reach a 

 correct zero position. 

 Provision for sealing: 

 Provision must be made for sealing electronic adjustable components ..................G-S.8. (1/1/90) 

 A security seal must be affixed to any adjustment mechanism designed to be 

 sealed......................................................................................................................G-UR.4.5. 

2. Measuring elements. 

Determine that system has an effective vapor elimination system and that vent 

lines are suitably rigid. ...........................................................................................S.2.1. 

Verify that means are provided for determination of product temperature.............S.2.6. (1/1/85) 

Determine that provision is made for applying security seals to the meter and to 

the automatic temperature compensating system, and that security seals are intact 

on both....................................................................................................................G-UR.4.5., S.2.2., S.2.7.3. 

3. Marking. 

Device is to be permanently marked with a make, model and 

serial number . ........................................................................................................G-S.1.(a), 

 G-S.1.(c)(1/1/03), 

 G-S.1.(d)(1/1/68), 

 G-S.1.(e)(1/1/86), 

 G-S.1.(f)(1/1/01) 

Inspection (cont.):
Loading-Rack Meters

EPO No. 25 

Rev 3/02 25-5 

 All switches, lights, displays, pushbuttons, and other operational controls and 

 features must be clearly and definitely identified. .........................................................G-S.6. (1/1/77) 

 The limitation on a device's use shall be clearly and permanently marked on any 

 device intended to measure accurately: .........................................................................S.4.1. 

 a. only products having particular properties, 

 b. only under specific installation conditions, or 

 c. only when used in conjunction with specific accessory equipment. 

 Designed minimum and maximum discharge rates must be clearly and permanently 

 marked on meter. Minimum discharge rate shall not exceed 20 percent of the maximum 

 discharge rate.................................................................................................................S.4.3.1. 

4. Installation. 

 Device must be readily accessible for purposes of testing. Assistance shall be provided by 

the firm if needed. ..................................................................................................G-UR.2.3., G-UR.4.4. 

 Examine discharge line and valves to insure that measured liquid cannot be diverted 

 From the measuring chamber or discharge line and that any directional flow valves 

 are automatic in operation. .....................................................................................S.2.3., S.3.1. 

No leaks should exist in the system on the outlet side of the meter........................G-UR.4.1., S.3.1. 

 Note: If leaks are detected on the inlet side of the meter, a notation should be made 

on the inspection report and the firm should be made aware of the location of the 

leak for purposes of safety. 

Examine the system and any associated equipment to insure that the assembly, 

installation, and construction do not facilitate fraud..............................................G-S.2. 

 The details of the installation must be proper and must not adversely affect system 

 performance. The actual maximum discharge rate must not exceed that specified 

 by the manufacturer................................................................................................G-UR.2.1., UR.2.1., UR.2.2. 

5. Selection and use. 

 Device must be suitable for the service in which it is used with respect to the 

 elements of design, including flow rate, computing capability, the details of 

 its indicating and recording elements, and the value of its smallest unit and unit 

 prices. Device must also be suitable for use in the environment in which it is 

 installed. .................................................................................................................G-UR.1.1., G-UR.1.2 

Device and any associated equipment are to be operated and maintained as 

intended by the manufacturer .................................................................................G-UR.3.1., G-UR.4.1. 

Inspection (cont.):

If a device is equipped with a mechanical automatic temperature compensator, 

it shall be connected, operable, and in use at all times. ..........................................UR.3.6.1.1. 

6. Devices equipped with automatic temperature compensating systems. 
Loading-Rack Meters

EPO No. 25 

Rev 3/02 25-6 

 Provision must be made to deactivate the automatic temperature compensating 

 system so that the meter may indicate and record, if equipped to record, in terms 

 of the uncompensated volume. ...............................................................................S.2.7.2. 

 Thermometer well must be provided for determination of the temperature of 

the liquid.................................................................................................................S.2.7.4. 

Primary indicating and recording elements on devices equipped with automatic 

temperature compensating systems shall be marked to show that the volume 

delivered has been adjusted to 15.5 OC (60 oF)......................................................S.4.3.2. 

Test Notes:

1. Check for the proper operation of the level indicators on the prover and level the 

 prover. 

2. Connect safety interlock and ground cable. If applicable, connect the vapor recovery 

 hose. 

3. Verify that all valves in the proving system are closed and that the prover pumping 

 mechanism is functional. 

4. Note the totalizer reading. Totalizer should be checked before and after each draft to 

 determine its proper operation. 

Test Notes (cont.):

5. Care should be exercised to insure that the temperature difference between product 

 in the prover and in the meter is small...........................................................................N.2. 

6. For top-loading provers, take precautions to minimize splashing and to maintain the 

 spout fill in a consistent position. 

7. Examine printed tickets and invoices: 

Wear appropriate personal protection equipment such as 

petroleum-resistant, non-skid safety shoes (to prevent 

possible injury from spills or slipping on slick surfaces), 

protective clothing, eye protection (to prevent injury from 

splashed product), and a hard hat (to prevent injury from 

overhangs and projections on vehicle tank truck). 

Use proper grounding procedures! 

Device operator should be present at all times during testing. 
Loading-Rack Meters

EPO No. 25 

Rev 3/02 25-7 

 a. Print a ticket after each test draft, if device is so equipped..................................G-S.5.6. 

 b. For devices of the computing type: 

1) Check price computations on indicator and on printed indications. ........S.1.7.2. 

2) On any printed ticket containing the total computed price, the total 

 volume of the delivery and the price per gallon or liter shall be shown 

 either machine printed or in clear handscript. ........................................UR.3.4. 

 c. Check all indicated and recorded values for proper comparability......................G-S.5.2.2. 

d. For systems equipped with automatic temperature compensation, check 

 invoices to determine if: 

1) deliveries which are adjusted to 15.5 °C (60 oF) show that the volume has been adjusted 

to 15.5 °C (60 oF).................................................................................UR.3.6.1.2.(a) 

2) in the case of an electronic wholesale device equipped with an automatic 

temperature compensating system, the API gravity, specific gravity, 

or coefficient of expansion; product temperature; and gross reading 

are also indicated. .................................................................................UR.3.6.1.2.(b) 

e. For devices with nonautomatic temperature compensating systems, check invoices 

 to determine that: if the volume of the product delivered is adjusted to 15.5 °C 

 (60 oF), this is stated on the invoice along with the product temperature used 

 in making the adjustment........................................................................................UR.3.6.2.1., UR.3.6.2.2. 

 f. In addition to tickets printed during inspection and testing, several examples of 

 actual used tickets are to be examined. This serves to verify the format of and 

 information on actual printed tickets. 

8. Prover readings are to be determined by reading the bottom of the meniscus for 

 transparent liquids, and the top of the meniscus for opaque liquids. 

9. When monitoring drainage of the prover, one of the following methods should 

 be followed depending on prover design. Precautions should be taken to 

 insure that drainage procedure is followed in a consistent manner for each test. 

 

a. If the prover has a lower neck equipped with a drain sight glass, close the 

 drain valve prior to the liquid level reaching the zero mark indicator. 

 After 30 seconds drain time, open the small drain-off valve and lower the 

 liquid level to the zero mark. (Do not adjust the liquid level again, 

Test Notes (cont.):

 even if continued drainage raises the liquid level above the zero mark before the 

 test is started.) 

b. If the prover is not equipped with a lower sight glass, leave the drain valve open 

 until continuous flow ceases and dripping commences. Close drain valve after 

 30 seconds. 

10. Temperature readings are to be taken to the nearest 0.25 °C or 0.5 oF or for digital thermometers, to 

the nearest increment. Take the temperature of the test liquid in the prover immediately following each 
Loading-Rack Meters

EPO No. 25 

Rev 3/02 25-8 

accuracy test. For provers equipped with more than one thermometer, the temperature of the test liquid 

is the mathematical average of the individual readings. 

 A thermometer placed in the thermowell adjacent to the meter is to be used to determine 

 meter temperature. Meter temperature is to be taken at 1/3 and 2/3 prover capacity 

 during each delivery and averaged. 

11. Automatic-stop-mechanism must stop flow within one-half the minimum interval 

 indicated ........................................................................................................................S.2.4. 

Test Procedure:

1. Wet prover. 

2. Empty prover. Allow a 30-second drain period each time the prover is emptied, using 

 one of the methods outlined in the Test Notes. The amount of time between wetting the 

 prover and the first test draft should be minimal. 

3. Insert a meter ticket and set preset stop mechanism for the rated capacity of the prover. 

 Reset the meter to zero. 

4. Start the pump, then open the prover delivery valve. 

Test Procedures (cont.):

 If any test result is close to or outside of applicable tolerance, then repeat the test. 

 If two consecutive tests are found to exceed applicable tolerance values, 

 discontinue accuracy test and proceed to next portion of EPO. 

For Repair Personnel:

Two test runs should be performed to insure repeatability. The difference between the high and low 

readings of these two consecutive runs should not exceed 0.05 percent of the prover's certified volume. 

If test results exceed applicable tolerance values, the meter should be adjusted at this point. Repair 

Use proper lifting techniques to lift and move equipment! 

Be aware of and attempt to eliminate potential 

ignition sources in or near the inspection site. 

Be aware of vehicular and pedistrian traffic in the area. 
Loading-Rack Meters

EPO No. 25 

Rev 3/02 25-9 

personnel should follow company policy regarding adjustment of meter; for meters equipped with a 

temperature compensator, it may be necessary to first deactivate the temperature compensator prior to 

making any adjustment. 

A check for the performance of the temperature sensor should be performed at the end of each accuracy 

test. Utilize the section at the end of each worksheet to analyze the performance of the sensor. Should a 

variation of 1 °C or 2 oF exist for two consecutive runs, the normal operating thermometer must be recalibrated against a National Institute of Standards and Technology traceable thermometer. 

5. Accuracy tests. 

 a. Nontemperature-compensated meters. 

 Temperature corrections are to be made for accuracy tests to account for any 

 difference between the temperature of the liquid passing through the meter 

 and the liquid in the prover..................................................................................N.5. 

 1) Normal test--full flow....................................................................................N.4.1., N.4.1.1., N.4.1.2., 

T.2.3. 

 a) Fill prover in a manner simulating actual use and determine actual flow 

 rate. Test should be run at the maximum discharge rate anticipated 

 under the conditions of the installation. Actual rate of flow should be 

 within manufacturer's ratings of minimum and maximum flow...............G-UR.3.1., UR.2.2. 

 b) Verify that all valves are closed and that prover remains level. 

 Examine prover piping to insure that there is no entrapment of air and 

 that there are no leaks. 

 c) Disconnect the bottom loading coupler or remove the loading spout 

 from the liquid. 
Loading-Rack Meters

EPO No. 25 

Rev 3/02 25-10 

Test Procedure (cont.):

 d) Allow time for product settling and foam dissipation prior to taking 

 prover reading. 

 e) Read the thermometers as described in Test Notes, and record the 

 reading to the nearest 0.25 °C or 0.5 oF or for digital thermometers, to 

 the nearest increment. 

f) For an analog device, record ending meter reading to the nearest 0.1 gallon. 

 For a digital-indicating device, record the meter indication to the smallest 

 quantity division available, e.g., test mode indication. Check totalizer against 

 actual amount dispensed. 

 

 g) Disconnect vapor recovery hose and then drain prover. 

 h) Use appropriate worksheet to determine meter error. 

 2) Special test--slow flow...................................................................................N.4.2., N.4.2.4., T.2.3. 

 a) Reconnect vapor recovery hose, if applicable. 

 b) Fill prover at the minimum discharge rate marked on the device 

c) Repeat steps (b) through (h) of part 5.a.(1) above. 

 b. Temperature compensated meters. 

 For meters that indicate in "net" gallons. With temperature compensator activated: 

1) Normal test--full flow (do not deactivate temperature compensating 

 system). ...........................................................................................................N.4.1., N.4.1.1., N.4.1.2., 

T.2.3. 

 a) Fill prover as described in part 5.a.(1) above. 

 b) Obtain temperature of product at meter at 1/3 and 2/3 prover capacity. 

 Determine the average. 

 c) Follow remaining steps in part 5.a.(1) above, using the worksheet for 

 compensated meters to determine meter error. 

 Deactivate temperature compensator: 

 1) Normal test--full flow ....................................................................................N.4.1., N.4.1.1., N.4.1.2., 

T.2.3. 

 Follow testing procedure described in part 5.a. above for normal test, 

 uncompensated meters, determine meter error using worksheet for 

 uncompensated meters. 

 2) Special test--slow flow..................................................................................N.4.2., N.4.2.4., T.2.3. 

Follow testing procedure described in part 5.a.(2) above for special test, 
Loading-Rack Meters

EPO No. 25 

Rev 3/02 25-11 

Test Procedure (cont.):

uncompensated meters. Determine meter error using worksheet for 

uncompensated meters. 

Reactivate temperature compensator. 

c. Temperature compensated meters. 

 For meters that indicate or record in "gross" gallons (uncompensated) and 

 "net" gallons (compensated). 

 1) Accuracy of "gross" gallons is to be determined following the test procedure 

 for non-temperature compensated meters in part 5.a.(1) and (2) above to 

 perform both normal and special tests. 

 2) Accuracy of "net" gallons is to be determined as follows: 

 a) For each test run in part c.(1) above, obtain the temperature of product at 

 meter at 1/3 and 2/3 capacity of prover. 

 b) Correct prover volume reading to 15.5 OC (60 oF), using the worksheet for 

 compensated meters. 

6. For automatic temperature compensating systems. The difference between the meter error for 

 tests performed with and without the automatic temperature compensating system 

 activated shall not exceed 0.2 percent for mechanical ATCS and 0.1 percent for electronic ATCS of the 

 test draft. The results of each test shall be within applicable tolerances.......................T.2.3.5.(1/1/88) 

7. Security seal: 

Adequate provision shall be made for applying a security seal..............................S.2.2 

Affix a security seal to the adjustment mechanism, as appropriate. .......................G-UR.4.5. 

8. For a wet-hose system, check the effectiveness of the anti-drain valve.........................S.3.9. 

9. For a dry-hose system, check for complete drainage of the hose. .................................S.3.4.(b) 

10. Radio Frequency Interference (RFI)/Electromagnetic Interference (EMI) (only if a problem is suspected). 

using only equipment on site in the vicinity of the metering system, perform a test for radio 

frequency/electromagnetic interference. Results of this test must indicate that use of such 

equipment does not adversely affect performance of the metering system....................G-N.2., G-UR.1.2., 

 G-UR.3.2., G-UR.4.2. 

 

Test Procedure (cont.):
Loading-Rack Meters

EPO No. 25 

Rev 3/02 25-12 

Use extreme caution when switch-loading product! 

Take precautions to isolate equipment when 

transporting it to avoid exposure to hazardous fumes. 
Liquefied Petroleum Gas Motor-Fuel Dispensers

EPO No. 26 

Rev. 3/02 26- 1

 

Examination Procedure Outline for

 

Liquefied Petroleum Gas Motor-Fuel Dispensers

It is recommended that this outline be followed for all LP gas motor-fuel dispensers. Examination procedures for 

other types of LP gas liquid meters are given in EPO No. 27. 

SAFETY NOTES 

When excerpting this Examination Procedure Outline for duplication, "Safety Considerations" section and

the "Glossary of Safety Key Phrases" should be duplicated and included with the outline. 

The inspector is reminded of the importance of evaluating potential safety hazards prior to an inspection and 

taking adequate precautions to avoid personal injury or damage to the device. The inspector should read and 

be familiar with the introductory section on safety found at the beginning of this publication. As a minimum, 

the following safety precautions should be noted and followed during the inspection. Definitions of each 

reminder are found in the "Glossary of Safety Key Phrases" at the back of this publication. 

Safety policies and regulations vary among jurisdictions. It is essential that inspectors or servicepersons be 

aware of all safety regulations and policies in place at the inspection site and to practice their employer’s 

safety policies. The safety reminders included in this EPO contain general guidelines useful in alerting 

inspectors and servicepersons to the importance of taking adequate precautions to avoid personal injury. 

These guidelines can only be effective in improving safety when coupled with training in hazard recognition 

and control. 

 Clothing Material Safety Data Sheets (MSDS) 

 Electrical Hazards Nature of Product 

 Emergency Procedures Personal Protection Equipment 

 e.g., Safety Shoes 

 Eye Protection Safety Aprons, Respirators, Gloves, Barrier

Cream, Etc., if deemed necessary. 

 Fire Extinguisher Hard Hat -- for protection from overhang

in rear of vehicle tank truck 

 First Aid Kit 

 Safety Cones/Warning Signs 

 Grounding 

 Static Discharge 

 Ignition Sources 

 Support -- for prover 

 Lifting 

 Switch Loading 

 Location 

 Traffic 

 

also: Wet/Slick Conditions Transportation of Equipment 

 Chemicals, Petroleum Products, 

 And Hazardous Materials 

 Obstructions 
Liquefied Petroleum Gas Motor-Fuel Dispensers

EPO No. 26 

Rev. 3/02 26- 2

Inspection: 

Safety First !!! 

 H-44 General Code and LPG 

and AA Liquid-Measuring 

Devices Code References 

1. Indicating and recording elements. 

Design ...................................................................................................................S.1.1. 

 Readability .............................................................................................................G-S.5., G-UR.3.3., S.1.2., 

S.1.3. 

Unit price and product identity...............................................................................S.1.5.1. 

 Advancement and return to zero.............................................................................S.1.1.4., S.1.4.1., S.1.4.2., 

UR.2.1. 

Provision for sealing...............................................................................................G-S.8. (1/1/90), G-UR.4.5. 

2. Measuring elements. 

Vapor elimination...................................................................................................S.2.1., S.2.4. 

Security seals..........................................................................................................G-UR.4.5., S.2.2., S.2.6.2. 

Thermometer well ..................................................................................................S.2.5. 

Automatic temperature compensation....................................................................S.2.6., S.2.6.1., UR.2.4.

 Check the inspection site carefully for safety hazards and 

take appropriate precautions pay particular attention to the condition 

 of the product storage tank and valves.

 Check to be certain that the ground surface of the inspection site is 

sufficiently strong and rigid to support the prover when it is filled with product 

 don't forget to chock the wheels of the prover. 

Learn the nature of hazardous products used at or near the inspection site; 

obtain and read copies of MSDS. 

 Know emergency procedures (particularly for this location) and the location and operation 

 of fire extinguisher and emergency shut-offs.

 Be sure that a constant supply of water is available for cooling tanks in an emergency 

Post safety cones/warning signs and be aware of vehicular and pedestrian traffic patterns. 

Use caution moving around in wet, slippery areas 

 and in climbing on prover, storage tanks, and vehicles. 

Use personal protection equipment and clothing appropriate for the inspection site. 

If exposed wiring or other factors cause hazardous testing conditions, 

it is recommended that the testing be discontinued until the unsafe conditions are corrected. 

Be sure that a first aid kit is available and that the kit. 
Liquefied Petroleum Gas Motor-Fuel Dispensers

EPO No. 26 

Rev. 3/02 26- 3

Inspection (cont.):

3. Marking requirements ...................................................................................................G-S.1., G-S.6.(1/1/77), 

G-S.7., S.4. 

4. Discharge line and valves..............................................................................................S.2.3., S.3., UR.1.2., 

UR.2.2., UR.2.3. 

Facilitation of fraud................................................................................................G-S.2. 

5. General considerations. 

 Selection.................................................................................................................G-UR.1.1. 

 Use and maintenance..............................................................................................G-UR.3.1., G-UR.4.1. 

 Installation..............................................................................................................G-UR.2.1., G-UR.2.2., 

UR.1.1., G-S.2., G-S.3. 

 Accessibility...........................................................................................................G-UR.2.3. 

 Assistance...............................................................................................................G-UR.4.4. 

 Testing devices at a central location.......................................................................G-UR.4.6.(a) 

Pretest Determinations: 

1. Determine that the test liquid is similar in character to the liquid to be measured 

 commercially.................................................................................................................N.1. 

2. Tolerances. 

 Applicable requirements.........................................................................................G-T., T.1. 

 Tolerance values.....................................................................................................T.2. 

 Repeatability .........................................................................................................T.3. 

 Automatic temperature-compensating systems ......................................................T.4. 

Test Notes: 

 

 Wear appropriate personal protection equipment such as

static-resistant, nonskid safety shoes (to avoid potential 

 ignition source and to prevent possible injury from slipping 

 on slick surfaces), protective clothing, eye protection 

 (to prevent injury from product), and a hard hat (to prevent 

 injury from overhangs and projections on the prover 

 and at the test site). 

 Use proper grounding procedures ! 

 Be sure that prover is equipped with an explosion-proof motor. 

 Carefully inspect electrical supply lines for 

 test equipment for wear or damage; correct 

 potentially hazardous conditions before use; 

protect lines from damage during use. 

Remove fire extinguisher from storage 

receptacle and set out for easy access.
Liquefied Petroleum Gas Motor-Fuel Dispensers

EPO No. 26 

Rev. 3/02 26- 4

Test Notes (cont.):

1. Wet prover (fill to nominal capacity). Allow 30-second drain period each time 

 prover is emptied. 

2. Read temperature and pressure of product in prover immediately following 

 each test draft. ...............................................................................................................N.5. 

3. If dispenser is equipped with a recording element, print ticket after each test run........G-S.5.6., S.1.1.6., UR.2.5. 

4. If computing type, check computation ..........................................................................G-S.5.5., S.1.1.5., S.1.5.2. 

5. To determine proper operation of totalizers, observe and record the totalizer 

 indication before and after all test drafts. 

Test:

Nontemperature-compensated meters

Read temperature of product at meter at one-third and two-thirds prover capacity..............N.5. 

1. Normal test--full flow, normal tolerance.......................................................................N.2., N.3., N.4.1., N.5., 

T.2. 

2. Repeat normal test. 

3. Special test--slow flow, special tolerance .....................................................................N.2., N.4.2.1., N.5., T.2. 

If the result of any test is close to or outside the applicable tolerance, repeat that test. 

Temperature-compensated meters

1. Normal test--full flow, normal tolerance. (Do not deactivate temperature 

compensator.) .......................................................................................................................N.2., N.3., N.4.1.1., N.5., 

T.2. 

2. Deactivate temperature compensator and repeat normal test ........................................N.2., N.3., N.4.1., N.5., 

T.2., T.4. 

3. Special test--slow flow, special tolerance......................................................................N.2., N.4.2.1., N.5., T.2. 

If the result of any test is close to or outside the applicable tolerance, repeat that test. 

Test (cont.):

Use proper lifting techniques to lift and move equipment !

 Be aware of and attempt to eliminate potential 

 ignition sources in or near the inspection site. 

 Be aware of vehicular and pedestrian traffic in the area. 
Liquefied Petroleum Gas Motor-Fuel Dispensers

EPO No. 26 

Rev. 3/02 26- 5

Reactivate temperature compensator. 

Security seal. Apply lead-and-wire seals to secure meter and temperature adjusting mechanisms. Also seal register 

to the meter. 

Note final totalizer reading and record the number of gallons of product dispensed during test on official report. 
Liquefied Petroleum Gas Liquid-Measuring Devices

EPO No. 27 

Rev. 3/02 27-1 

 

Examination Procedure Outline for 

Liquefied Petroleum Gas 

Liquid-Measuring Devices

It is recommended that this outline be followed for all LP gas liquid meters except motor-fuel dispensers. 

SAFETY NOTES 

When excerpting this Examination Procedure Outline for duplication, the "Safety Considerations" section 

and the "Glossary of Safety Key Phrases" should be duplicated and included with the outline. 

The inspector is reminded of the importance of evaluating potential safety hazards prior to an inspection 

and taking adequate precautions to avoid personal injury or damage to the device. The inspector should read and 

be familiar with the introductory section on safety found at the beginning of this publication. As a minimum, the 

following safety precautions should be noted and followed during the inspection. Definitions of each reminder 

are found in the "Glossary of Safety Key Phrases" at the back of this publication. 

Safety policies and regulations vary among jurisdictions. It is essential that inspectors or servicepersons be 

aware of all safety regulations and policies in place at the inspection site and to practice their employer’s 

safety policies. The safety reminders included in this EPO contain general guidelines useful in alerting 

inspectors and servicepersons to the importance of taking adequate precautions to avoid personal injury. 

These guidelines can only be effective in improving safety when coupled with training in hazard recognition 

and control.

 Clothing Material Safety Data Sheets (MSDS) 

 Electrical Hazard Nature of Product 

 Emergency Procedures Personal Protection Equipment 

 e.g., Safety Shoes 

 Eye Protection Safety Aprons, Respirators, Gloves, 

 Barrier Cream, etc. if deemed necessary 

 Fire Extinguisher Hard Hat – for protection from overhead 

 hazards 

 First Aid Kit Safety Cones/Warning Signs 

 Grounding Static Discharge 

 Ignition Sources Support – for prover 

 Lifting Switch Loading 

 Location Traffic 

 Transportation of Equipment 

 also: Wet/Slick Conditions 

 Chemicals, Petroleum Products, and Hazardous Materials 

 Obstructions and Overhead Hazards 
Liquefied Petroleum Gas Liquid-Measuring Devices

EPO No. 27 

Rev. 3/02 27-2 

 

Inspection: 

Safety First !!! 

 

H-44 General Code and LPG 

and AA Liquid-Measuring 

Devices Code References 

1. Indicating and recording elements. 

 Design ....................................................................................................................S.1.1. 

 Readability .............................................................................................................G-S.5., G-UR.3.3., S.1.2., 

S.1.3. 

 Ticket Printer (vehicle-mounted systems)..............................................................UR.2.6. 

 Unit price and product identity...............................................................................S.1.5.1. 

 

 Check the inspection site carefully for safety hazards and take appropriate precautions 

pay particular attention to the conditionof the product storage tank and valves. 

 Check to be certain that the ground surface of the inspection site is sufficiently strong and rigid to 

 support the prover when it is filled with product don't forget to chock the wheels of the prover. 

 Learn the nature of hazardous products used at or near the inspection site 

obtain and read copies of MSDS. 

Know emergency procedures (particularly for this location); post safety cones/warning signs and be aware 

of the location and operation of fire extinguisher and emergency shut-offs. 

 Be sure that a constant supply of water is available for cooling tanks in an emergency. 

Post safety cones/warning signs and be aware of vehicular and pedestrian traffic patterns. 

Use caution moving around in wet, slippery areas 

 and in climbing on prover, storage tanks, and vehicles. 

 Use personal protection equipment and clothing 

 appropriate for the inspection site. 

 If exposed wiring or other factors cause hazardous 

 testing conditions, it is recommended that the testing be 

 discontinued until the unsafe conditions are corrected. 

 Be sure that a first aid kit is available and that the 

 kit is appropriate for the type of inspection activity. 
Liquefied Petroleum Gas Liquid-Measuring Devices

EPO No. 27 

Rev. 3/02 27-3 

Inspection (cont.):

 Advancement and return to zero.............................................................................S.1.1.4., S.1.4.1., S.1.4.2., 

UR.2.1., S.1.6.1. 

 Provision for sealing...............................................................................................G-S.8. (1/1/90), G-UR.4.5. 

2. Measuring elements. 

 Vapor elimination...................................................................................................S.2.1., S.2.4. 

 Security seals..........................................................................................................G-UR.4.5., S.2.2., S.2.6.2. 

 Thermometer well ..................................................................................................S.2.5. 

 Automatic temperature compensation....................................................................S.2.6., S.2.6.1., UR.2.4. 

3. Marking requirements ...................................................................................................G-S.1., G-S.6.(1/1/77), 

G-S.7., S.4. 

4. Piping. 

 Discharge line and valves.......................................................................................S-2.3., S.3., UR.2.2., 

UR.2.3. 

Facilitation of fraud................................................................................................G-S.2. 

5. General considerations. 

 Selection.................................................................................................................G-UR.1.1. 

 Use and maintenance..............................................................................................G-UR.3.1., G-UR.4.1. 

 Installation..............................................................................................................G-UR.2.1., G-UR.2.2., 

UR.1.1., G-S.3. 

Accessibility...........................................................................................................G-UR.2.3. 

Assistance...............................................................................................................G-UR.4.4. 

Testing devices at a central location.......................................................................G-UR.4.6.(a) 

Pretest Determinations: 

1. Determine that the test liquid is similar in character 

 to the liquid to be measured commercially....................................................................N.1. 

2. Tolerances. 

 Applicable requirements.........................................................................................G-T., T.1. 

 Tolerance values.....................................................................................................T.2. 

 Repeatability ..........................................................................................................T.3. 

 Automatic temperature-compensating system........................................................T.4. 
Liquefied Petroleum Gas Liquid-Measuring Devices

EPO No. 27 

Rev. 3/02 27-4 

Test Notes: 

1. Wet prover (fill to nominal capacity). Allow 30-second drain period each time prover 

 is emptied. 

2. Read temperature and pressure of product in prover immediately following each test 

 draft ...............................................................................................................................N.5. 

3. If dispenser is equipped with a recording element, print ticket after each test run........G-S.5.6., S.1.1.6., 

UR.2.5., UR.2.6. 

4. If computing type, check computation ..........................................................................G-S.5.5., S.1.1.5., S.1.5.2. 

5. To determine proper operation of totalizers, observe and record the totalizer indication 

 before and after all test drafts. 

Test:

 

Wear appropriate personal protection equipment such as static-resistant, nonskid safety shoes 

(to avoid potential ignition source and to prevent possible injury from slipping on slick surfaces), 

protective clothing, eye protection (to prevent injury from product), 

 and a hard hat (to prevent injury from overhangs and projections on the prover and at the test site). 

 

 Use proper grounding procedures! 

 Be sure that prover is equipped with an explosion-proof motor. 

 Carefully inspect electrical supply lines for test equipment for wear or damage; correct 

 potentially hazardous conditions before use; protect lines from damage during use. 

 

 Device operator should be present at all times during testing 

the operator (not the inspector) should operate the device under test.

Remove fire extinguisher from storage receptacle and set out for easy access. 

Use proper lifting techniques to lift and move equipment !

 Be aware of and attempt to eliminate potential 

 ignition sources in or near the inspection site. 

 Be aware of vehicular and pedestrian traffic in the area. 
Liquefied Petroleum Gas Liquid-Measuring Devices

EPO No. 27 

Rev. 3/02 27-5 

Test (cont.):

Nontemperature-compensated meters

Read temperature of product at meter at one-third and two-thirds prover capacity..............N.5. 

1. Normal test--full flow, normal tolerance ......................................................................N.2., N.3., N.4.1., N.5., 

T.2. 

2. Repeat normal test. 

3. Special test--slow flow, special tolerance .....................................................................N.2., N.4.2.2., N.5., T.2., 

N.4.2.3. 

If the result of any test is close to or outside the applicable tolerance, repeat that test. 

Temperature-compensated meters

1. Normal test--full flow, normal tolerance. (Do not deactivate temperature 

 compensator.) ................................................................................................................N.2., N.3., N.4.1.1., N.5., 

T.2. 

2. Deactivate temperature compensator and repeat normal test ........................................N.2., N.3., N.4.1., N.5., 

T.2., T.4., N.4.2.3. 

3. Special test--slow flow, special tolerance .....................................................................N.2., N.4.2.2., N.5., T.2., 

N.4.2.3. 

If the result of any test is close to or outside the applicable tolerance, repeat that test. 

Reactivate temperature compensator. 

Security seal. Apply lead-and-wire seals to secure meter and temperature adjusting mechanisms. Also seal register 

to the meter. 

Note audit trail information, if applicable. 

Note final totalizer reading and record on official report the number of gallons of product dispensed during test. 
Compressed Natural Gas

EPO No. 28 

Rev 3/02 28- 

 

1

 Examination Procedure Outline for 

 Compressed Natural Gas (CNG) 

 Retail Motor-Fuel Dispensers

It is recommended that this outline be followed for examining retail motor-fuel dispensers used to measure 

compressed natural gas. Non-retroactive requirements are followed by the applicable date in parentheses. 

SAFETY NOTES 

When excerpting this Examination Procedure Outline for duplication, the “Safety Considerations” section and the 

“Glossary of Safety Key Phrases” should be duplicated and included with the outline. 

The inspector is reminded of the importance of evaluating potential safety hazards prior to an inspection and taking 

adequate precautions to avoid personal injury or damage to the device. The inspector should read and be familiar with 

the introductory section on safety found at the beginning of this publication. As a minimum, the following safety 

precautions should be noted and followed during the inspection. Definitions of each reminder are found in the 

“Glossary of Safety Key Phrases” at the back of this publication. 

Safety policies and regulations vary among jurisdictions. It is essential that inspectors or servicepersons be aware of

all safety regulations and policies in place at the inspection site and to practice their employer’s safety policies. The 

safety reminders included in this EPO contain general guidelines useful in alerting inspectors and servicepersons to 

the importance of taking adequate precautions to avoid personal injury. These guidelines can only be effective in 

improving safety when coupled with training in hazard recognition and control. 

Asphyxiation Lifting 

 Chemicals, Petroleum Products, and Hazardous Materials Location 

 

 Clothing Material Safety Data Sheet (MSDS) 

 Electrical Hazards Nature of Product 

 Emergency Procedures Personal Protection Equipment 

 Eye Protection Safety Shoes 

 Fire Extinguisher Safety Cones/Warning Signs 

 First Aid Kit Static Discharge 

 Grounding Traffic 

 High Pressure Gas Transportation of Equipment 

 Ignition Source 
Compressed Natural Gas

EPO No. 28 

Rev 3/02 28- 

 

2

Equipment List:

The following criteria should be considered when selecting equipment for the test. 

Scale 

<intrinsic safety - scale meets Underwriters Laboratory (UL) Area Classification Class 1 Division 2 Group D (scale 

equipment must be located outside of classified area which is five feet from hose connection to dispenser) 

<capacity 

<appropriate division size 

<type of power source 

See the Appendix to EPO 28 for information on Scale Selection Criteria and Verifying Scale Accuracy. 

Mass Standards

<Class F 

Test Cylinder

< rating - must be equivalent to or greater than the service pressure marked on the device under test as required by 

the ANSI/IAS NGV 4.1/CSA 12.5 “NGV Dispensing Systems,” Standard for Natural Gas Vehicle Dispensing 

Systems 

<compatible fittings 

<bleed valve 

<pressure gauge 

<drain hose 

Note: Service pressure is the settled pressure at a uniform gas temperature of 21 oC (70 oF) and full gas content. 

It is the pressure for which the equipment has been constructed under normal conditions. This is different 

from the maximum working pressure. 

Optional Equipment:

<quick connect ground strap 

<cart 

<test cylinder supports (chocks) 

<weather shield/wind screen (for the weighing operation) 

H-44 General Code and 

Mass Flow Metering Devices 

 Code References 

Pretest Determinations: 

1. Select a site in the vicinity of the dispenser that is level and protected from wind and 

 weather to locate the scale. Ensure that the scale is given a sufficient warm-up time. 

2. Determine the scale error. 

 Sufficient test weights should be available to verify the gross load to be applied 

 During testing. The scale should be sensitive to 0.03 percent or less of the total 

 net weight of the product in the test cylinder. The value of the scale division 

 should not exceed one-tenth of the tolerance applied to the device. 
Compressed Natural Gas

EPO No. 28 

Rev 3/02 28- 

 

3

Pretest Determinations (cont.):

3. Scale capacity must be sufficient to weigh the test cylinder, optional chocks, and cart when filled to capacity 

with product. 

4. Tolerances. 

 Applicable requirements ........................................................................................G-T., T.1. 

 Applicable tolerances in NIST Handbook 44. 

 Basic values............................................................................................................T.2. 

 Applicable tolerances for CNG application. 

Inspection: 

Safety First !!! 

1

See the National Electrical Code or your local Occupational Safety and Health Administration (OSHA) for these 

requirements.

Check the inspection site carefully for safety hazards and take appropriate precautions 

pay particular attention to the condition of the test tank high pressure fitting and hoses. 

Learn the nature of hazardous products used at or near the inspection site; 

 obtain and read copies of Material Safety Data Sheet (MSDS). 

Know emergency procedures and location and operation 

of fire extinguisher and emergency shut-off system. 

Post safety cones/warning signs and be aware 

of vehicular and pedestrian traffic patterns. 

Use personal protection equipment and clothing 

appropriate for the inspection site. 

Make sure there is adequate ventilation to permit fumes to dissipate 

before proceeding with the inspection of the dispenser. 

If product is leaking (most CNG contains an odorant), 

or inadvertently released, or exposed wiring cause hazardous 

testing conditions it is recommended that the testing be 

immediately discontinued until the unsafe conditions are corrected. 

Be sure that a first aid kit is available and that the 

kit is appropriate for the type of inspection activity.

Use proper grounding procedures! 

Use proper low resistance grounding strap with 

recommended minimum conductance rating and correct 

connections consistent with the device under test.1
Compressed Natural Gas

EPO No. 28 

Rev 3/02 28- 

 

4

Inspection (cont.): 

1. General considerations. 

 Selection.................................................................................................................G-UR.1.1. 

 Equipment suitable for service 

 Installation..............................................................................................................G-UR.2.1., G-UR.2.2., 

UR.2.1. 

 Installed in accordance with manufacturer’s instructions does not 

 adversely affect operation nor impede communications between 

 indicator/recorder 

 Position...................................................................................................................G-UR.3.3. 

 During direct sales, indications are readable from a reasonable customer 

 and operator position. 

 Accessibility...........................................................................................................G-UR.2.3. 

 Located or such facilities provided for access to permit inspection, testing, and sealing 

 Assistance...............................................................................................................G-UR.4.4. 

 If required, operator to provide assistance in testing. 

 Use and maintenance..............................................................................................G-UR.3.1., G-UR.4.1. 

 Proper operation and maintenance of equipment 

2. Marking .........................................................................................................................G-S.1., S.5., G-UR.2.1.1. 

 Visible markings of the following information: 

 Pattern approval mark. 

 Name and address of manufacturer. 

 Model designation. 

 Model prefix .......................................................................................................(1/1/03) 

 Nonrepetitive serial number. 

 Serial number prefix ...........................................................................................(1/1/01) 

 Accuracy class ....................................................................................................(1/1/95) 

 Maximum and minimum flow rates (quantity/unit time). 

 Maximum working pressure. 

 Applicable temperature range (if other than -10 °C to 50 °C). 

 Minimum measured quantity. 

 Product limitations, if applicable. 

 Remanufacturer information as appropriate 

 Name and ID of manufacturer .......................................................................(1/1/02) 

 Model number if different from original model number ...............................(1/1/02) 

 Gasoline volume equivalent conversion factor ...................................................S.5.1 

3. Indicating and recording elements. 

 Design ....................................................................................................................G-S.5.1., S.1.1. 

 Shall have clear accurate indicator 

 Computing type2 ....................................................................................................S.1.2. 

 Mass display for inspection and testing 

 (pound displayed )5.660 = Gasoline Gallon Equivalent (GGE) displayed or 

 kilograms displayed ) 0.678 = Gasoline Liter Equivalent (GLE) displayed) 

 Units .......................................................................................................................S.1.3.1.1. 

 Quantity indications in GLE or GGE 

2

Indicates an exception to this requirement for dispensers used exclusively for fleet sales, other price contract sales 

and truck refueling.
Compressed Natural Gas

EPO No. 28 

Rev 3/02 28- 

 

5

Inspection (cont.): 

 Readability .............................................................................................................G-S.5., G-S.6. (1/1/77), 

 G-S.7. 

 Appropriate and accurate indicator and recorder

 Clear and identified operational controls and indicator 

 Lettering is clear and tends not to become obliterated. 

 Values of intervals..................................................................................................G-S.5.3. 

 Values of graduated intervals shall be uniform. 

 Maximum value of quantity-value divisions..........................................................S.1.3.3.(b) 

 Value of GLE is not greater than 0.01 GLE. 

 Value of GGE is not greater than 0.001 GGE. 

 Mass division shall not be greater than 0.001 kg or 0.001 lb.

 Auxiliary indications..............................................................................................S.2.6.1. 

 All money value and quantity divisions are identical to those of the 

 primary element. 

 Unit price and product identity...............................................................................S.2.5.1., S.2.5.2., S.2.5.3., 

 UR.3.1. 

 Display on each side. 

 Post information in direct sale2

. 

 Selection of unit price2

 Advancement and return to zero....................................................................S.2.1., S.2.2., S.2.8., UR.3.7. 

 Return indication to zero. 

 Does not return beyond zero position. 

Reset not operable during delivery. 

Return primary indicator to zero prior to delivery. 

 Provision for sealing......................................................................................S.8., G-UR.4.5., S.3.5. 

Metrological integrity protected by means of security. 

Affix a seal to adjustment mechanisms. 

 Recorded representations, point of sale systems ...........................................S.2.7. 

 Interface with cash register shall record : 

 Total volume 

 Unit price 

 Total computed price 

 Product identity 

4. Measuring elements. 

 Means of security on adjusting mechanism............................................................S.8., G-UR.4.5., S.3.5. 

 Adequate security or sealing for: 

 Measurement element. 

 Adjustable elements that affect accuracy 

 Zero adjustment mechanism. 

 Directional flow valves ..........................................................................................S.4.3. 

 Prevent flow reversal if it adversely affects device. 

5. Discharge hose ..............................................................................................................S.4.1., S.4.4., UR.1.1.

 No means of product diversion from measuring element. 

 It is apparent if there are two or more delivery outlets. 

2

Indicates an exception to this requirement for dispensers used exclusively for fleet sales, other price contract sales 

and truck refueling. 
Compressed Natural Gas

EPO No. 28 

Rev 3/02 28- 

 

6

Inspection (cont.): 

 Discharge valve may be installed on wet-hose type. 

 Other shutoffs are automatic or semiautomatic predetermined stop type or 

 operable by a separate tool or sealed open by means of security. 

 Length ....................................................................................................................UR.1.1. (1/1/98)

 Pressurizing the discharge hose..............................................................................S.3.7. 

 Discharge hose shall automatically pressurize prior to registration of delivery. 

6. Automatic Density Correction....................................................................................... S.3.6. 

Test Notes: 

 

1. Connect grounding cables to equipment. 

2. Determine the tare weight of the test tank and record. 

 Repeat this process prior to each delivery. 

3. To determine proper operation of totalizer, observe and record the totalizer indications 

 before and after all test drafts ........................................................................................S.7. 

4. After each test draft: 

a. Print ticket if device is so equipped.........................................................................G-S.5.6., UR.3.4. 

 All recorded values shall be digital. 

 Total-price, quantity, and unit price must be on the receipt. 

 b. Check price computations on all indicators (including consoles) and on recorded 

 representations........................................................................................................G-S.5.5. 

 Mathematical agreement of associated quantity or indication to the nearest one cent 

 c. Check all indicated and recorded values for proper comparability ........................G-S.5.2.2., S.2.5.4..(a), 

S.2.5.4.(b) 

 Check design of digital indication to determine that: 

 Like values agree. 

 Values coincide with analog value to nearest minimum graduation. 

Wear appropriate personal protection equipment such as 

 nonskid safety shoes (to prevent possible injury from 

 spills or slipping on slick surfaces), protective 

 clothing, and eye protection to prevent injury 

 from discharged product or propelled objects. 

 

 Be certain the scale is intrinsically safe! 

 Scale meets Underwriters Laboratory (UL) 

 Area Classification Class 1 Division 2 Group D 

 (Equipment location is outside of classified area 

 which is five feet from hose connection to dispenser).

 Do not leave an activated dispenser unattended!

 Ground test tank and scale properly during 

return of product.
Compressed Natural Gas

EPO No. 28 

Rev 3/02 28- 

 

7

Test Notes (cont.):

 Value rounds off to nearest minimum unit. 

 Digital zero display all places to the right, and at least one place to the left of the 

 decimal point. 

Tests:

 

1. Normal test ....................................................................................................................S.3.7.,N.4., N.6.1, T.2., T.3. 

 Computer jump: 

 Remove nozzle from dispenser and connect to test cylinder. (Test cylinder pressure 

 should not be greater than 200 psi to simulate an actual delivery.) 

 Turn nozzle valve from “OFF” position to “FILL” position. 

 Empty discharge hose. 

 Turn nozzle valve to “OFF” position. 

 Activate dispenser. 

 Observe dispenser indications, if computer jump occurs take appropriate action. 

NOTE: A test cylinder is not necessary for the computer jump test on dispensers equipped with 

 an autovent system. To test, turn dispenser on and observe the indication display for computer 

 jump when the dispenser shuts off. 

Minimum test drafts are as follows: 

 Place empty test cylinder on the scale. 

 Access mass display of the dispenser. 

 Tare weight of the test cylinder, chocks, and stand. 

 Connect the nozzle to the test cylinder. 

 Fill the test cylinder to 1/3 capacity full at maximum flow rate. 

 

 Disconnect the nozzle from the test cylinder. 

 Compare mass display to scale indication. 

 Determine dispenser error ......................................................................................T.2. 

 Leave product in test cylinder. 

 

Tests (cont.):

 Tare the weight of the test cylinder, chocks and stand. 

Ground test tank and scale properly during 

return of product. 

Use proper lifting techniques when lifting test tank! 

Be aware of and attempt to eliminate potential 

ignition sources in or near the inspection site. 

Be aware of vehicular and pedestrian traffic when 

moving between dispenser and product return area.

Stop delivery manually if delivery hose pressure exceeds 

allowable safety limits.
Compressed Natural Gas

EPO No. 28 

Rev 3/02 28- 

 

8

 Connect the nozzle to the test cylinder. 

 Begin the fill operation with product in the cylinder; fill cylinder to 2/3 capacity at 

 maximum flow rate. 

 Disconnect the nozzle from the test cylinder. 

 Compare mass display to scale indication. 

 Determine dispenser error ......................................................................................T.2. 

 Tare the weight of the test cylinder, chocks, and stand. 

 Connect the nozzle to the test cylinder. 

 Begin the fill operation with product in the cylinder; fill cylinder to capacity at 

 maximum flow rate. 

 

 Disconnect the nozzle from the test cylinder. 

 Compare mass display to scale indication. 

 Determine dispenser error ......................................................................................T.2. 

 Return product to owner/operator of dispenser......................................................UR.3.8. 

Place empty test cylinder on scale (scale may be supported by chocks and stand.) 

 Tare the weight of the test cylinder, chocks, and stand. 

 Connect the nozzle to the test cylinder. 

 Fill test cylinder to capacity at maximum flow rate. 

 Disconnect the nozzle from the test cylinder. 

 Compare mass display to scale indication. 

 Determine dispenser error ......................................................................................T.2. 

 Return product to owner/operator of dispenser. 

 Repeating previous tests .........................................................................................T.3.(a) 

 Applicable tolerance for multiple tests at the same flow rate 

 Return product to owner/operator of dispenser. 

 If the meter minimum measured quantity (MMQ) is less than the smallest test draft, 

 conduct a test at the MMQ value............................................................................N.4. 

NOTE: If 300 divisions (d) or 2.27 kilograms (5 pounds) is greater than 1/3 of the test cylinder capacity, then the 

test cylinder should be emptied to accommodate a delivery of at least 300 d or 2.27 kilograms (5 pounds) 

otherwise a larger tank is necessary. 

Stop delivery manually if delivery hose pressure exceeds 

allowable safety limits.

Stop delivery manually if delivery hose pressure exceeds 

allowable safety limits.

Stop delivery manually if delivery hose pressure exceeds 

allowable safety limits.
Compressed Natural Gas

EPO No. 28 

Rev 3/02 28- 

 

9

Tests (cont.):

2. Check effectiveness of zero-setback interlock ..............................................................S.3.8., UR3.6., UR.3.7. 

 No subsequent delivery until indicating and recording element returned to zero. 

 After delivery is complete the dispenser starting lever (mechanism) is shutoff, interlock 

engaged, and discharge nozzle is in the designed hanging position. (Note: This does not apply to 

nozzle control.) 

 Remove nozzle from hanging position. 

 Reset computer to zero and turn on dispenser. 

 Attempt to return the nozzle to its designed hanging position, carefully remove nozzle and connect it 

 to the test tank and open valve. Move the dispenser starting lever (mechanism) to “ON” position and 

 attempt to dispense product. (Note: This does not apply to nozzle control.) 

 Product should not flow without resetting the indications to zero. 

3. Check operation of low-flow cut-off valve ...................................................................UR.2.3. 

 Valve shall not be set lower than the minimum flow rate. 

 Valve stops registration when flow is below the low-flow cut-off value. 

 Connect nozzle to empty test tank and dispense product. Slowly throttle down on the 

 valve on the test tank to the minimum attainable flow rate. Product delivery should 

 not occur below the mass flow meter minimum flow rate. 

 

4 Power loss test...............................................................................................................S.2.4.1., S.2.4.2. 

 Transaction in progress at power loss, information shall be retainable for 15 minutes. 

 Device memory shall retain quantity of product and sales price during power loss. 

5. Security seal--apply wire security seal to secure adjusting mechanism 

 (if applicable) ................................................................................................................G-UR.4.5., S.3.5. 

 Note on the official report the number of gasoline gallon equivalents of product dispensed 

 during the test. 

After all equipment at a location has been tested, review results to determine compliance with 

 equipment maintenance and use of adjustments............................................................G-UR.4.1., G-UR.4.3. 
Compressed Natural Gas

EPO No. 28 

Rev 3/02 28- 

 

10

Appendix to EPO No. 28 

Compressed Natural Gas (CNG) 

Retail Motor-Fuel Dispensers 

Scale Selection Criteria3: 

The size of the division relative to the net load has a significant effect on the accuracy to which a meter can be 

tested. It will also affect the size of the test draft required to evaluate the meter. To keep the “rounding error” 

(caused by reading a scale to the nearest scale division) to an acceptably small level for a single weighing, the value 

of the scale division should not exceed one-tenth of the tolerance applied to the CNG dispenser. (For example, if 

applying the acceptance tolerance of "1.5 percent to a 50 kg or 100 lb test draft, the scale division should be no 

greater than 70 g or 0.15 lb; applying the maintenance tolerance of "2.0 percent the scale division should be no 

greater than 90 g or 0.20 lb.) The rounding error occurs in both the gross and tare weights, so it could represent as 

much as two-tenths of the tolerance. Either a high-resolution scale is needed, error weights should be used, or 

a larger test draft selected. A combination of these approaches may be used. If the size of the test draft must 

be small due to the available test cylinder(s) then a scale must be selected with an appropriate division size. 

If the scale available for testing has a relatively large division size then the size of the test draft must be 

increased accordingly. 

For example, if a CNG dispenser is to be tested using a scale with a 5 g or 0.01 lb division, error weights should be 

used to increase readability to the nearest 0.5 g or 0.001 lb for the gross and tare weights. Each weight value is, 

thus, "0.5 g or "0.001 lb or to the nearest 0.5 g or 0.001 lb, but since there are two weighings, gross and tare, the 

potential for total rounding error is 1 g or 0.002 lb. The acceptance tolerance for a CNG mass flow meter is "1.5 

percent. To limit the error for each weighing to one-tenth of the tolerance, the minimum test draft must be equal to: 

( )

( ) g kg g 666.67 0.67

0.015

1.0 10 = = × or 

( )

( ) lb lb 1.333

0.015

0.002 10 = ×

Thus, if a scale with 0.5 g or 0.001 lb divisions is used, or a scale with 5 g or 0.01 lb divisions and error weights to 

0.5 g or 0.001 lb is used and a tolerance of "1.5 percent is applied, the minimum test draft is recommended to be at 

least 0.67 kg or 1.34 lb. Other considerations may apply when determining minimum test draft size such as average 

customer delivery and meter size. (See also EPO discussion concerning determination of minimum test draft size.) 

Verifying Scale Accuracy: 

The Fundamental Considerations of Handbook 44, state it is necessary to limit the total error in a standard used 

without corrections to less than one-third of the tolerance of the device under test. For example, if applying the 

acceptance tolerance of "1.5 percent to a CNG meter, this means the scale must be accurate to at least 0.5 percent. 

Consequently, it is necessary to thoroughly test the scale, verify that its results repeat very well, correct for any 

errors determined during the scale test, and use the scale properly. This takes considerable time and care under field 

conditions. For devices with larger applicable tolerances (large test drafts), the requirements for the test may not be 

as stringent. 

3

The scale selection criteria and minimum test draft size for mass flow meter technology are discussed in the 1987 

Report on the Specifications and Tolerances Committee Agenda Item 330-2. 
 G-1 

Glossary of Safety Key Phrases

NOTE: When excerpting an Examination Procedure Outline for duplication, the "Safety Considerations" section 

at the beginning of this publication and this "Glossary" should also be duplicated and included with the 

outline.

Prior to using the safety information contained in the EPO's and in this glossary, the reader should review the "Safety 

Considerations" section at the beginning of this publication. 

Before proceeding with the inspection and testing of a weighing or measuring device, the inspector or serviceperson 

should be completely familiar with all safety regulations and policies in effect at the inspection location. Such 

regulations and policies include federal, state, or local Occupational Safety and Health Administration (OSHA) 

regulations, safety policies established by the firm in which the inspection is taking place, and safety policies 

established by the inspector's or serviceperson's employer. 

The safety reminders included in this publication are not intended to include all possible safety precautions which 

should be taken before proceeding with the inspection of a weighing or measuring device, nor are the listings of safety 

information and contacts a comprehensive source of safety information and guidance. Additional information is 

available on various safety topics from sources such as OSHA. 

Safety policies and regulations vary among jurisdictions. It is essential that inspectors or servicepersons be 

aware of all safety regulations and policies in place at the inspection site and to practice their employer’s safety 

policies. The safety reminders included in this EPO contain general guidelines useful in alerting inspectors and 

servicepersons to the importance of taking adequate precautions to avoid personal injury. These guidelines can 

only be effective in improving safety when coupled with training in hazard recognition and control. 

The following key phrases are used throughout this publication to serve as reminders to the inspector or serviceperson 

to practice safety as a routine part of their work. 

Chemicals, Petroleum Products, and Hazardous Materials:

 Be familiar with the nature of the products at an inspection site that is located in a plant or other facility which 

handles, uses, or packages chemicals, petroleum products, or hazardous materials; it is essential that the 

inspector or serviceperson be familiar with the nature of the product and any protective measures which 

should be taken prior to working around the product. For example, some products may cause injury through 

exposure to the skin or through inhalation of the fumes or airborne particulates. Similarly, caustic products 

may also damage field standard weights or measures or equipment used in the test process. 

 Determine whether or not protective clothing or equipment is needed prior to working with the product. 

 Material Safety Data Sheets (MSDS's) can provide much of the basic information about the hazards involved 

with a product. The manufacturer of the product should be able to provide further information about the 

product. Several sources of information concerning chemicals, petroleum products, and hazardous materials 

are listed below. 

 

 
 G-2 

 American Chemical Society American Chemistry Council 

 1155 16th Street, N.W. 1300 Wilson Blvd. 

 Washington, DC 20036 Arlington, VA 22209 

 800-227-5558 (U.S. only) (703) 741-5000 

 (202) 872-4600 (outside the U.S.) 

 FAX# (202) 872-4615 

 American Petroleum Institute 

 1220 L. Street, NW 

 Washington, DC 20005-4070 

 (202) 682-8000 

 FAX#: (202) 682-8232 

 Look for leakage or spillage of chemicals, petroleum products, or hazardous materials at or near the 

inspections site. Leakage or spillage of these products can be potentially hazardous if the 

inspector/serviceperson or facility employee is exposed to the product and is not wearing personal protection 

equipment. Additionally, any product collecting on the ground surface can result in slippery, unsafe 

conditions for an individual moving about the inspection area. If leaking or spilled product results in unsafe 

conditions at the inspection site, it is recommended that the testing procedure be discontinued until the unsafe 

conditions are corrected. 

Clothing:

 Synthetic clothing should not be worn when working around flammable products. Synthetic clothing melts at 

high temperatures; if the person wearing the synthetic clothing is exposed to flames, the clothing may melt 

and stick to the persons skin to result in severe burns. 

 Combustion can result when an ignition source is present and fuel and oxygen are also available. Many 

types of synthetic clothing also tend to build up a static charge; this can be dangerous as a potential ignition 

source around flammable products. 

 Use caution when wearing loose clothing (or hanging jewelry) around machinery such as conveyor belts, 

weight movers, meat hooks, gears, etc. The clothing (or jewelry) may become entangled in the machinery and 

result in personal injury. 

Electrical Hazards:

 Be particularly aware of potential electrical hazards in or near the inspection site when testing electronic 

devices or working in the vicinity of electrical equipment. Loose or exposed wiring and a frayed or worn 

electrical cord should be brought to the attention of management at the inspection site. Avoid standing on wet 

surfaces unless the electrical equipment is properly insulated and grounded. 

 Combustion can result when an ignition source is present and fuel and oxygen are also available. Electrical 

hazards may also be potential ignition sources when testing devices which dispense flammable products or 

working near flammable products. Be sure that provers and other test equipment are equipped with explosionproof motors. Always check the electrical supply lines for testing equipment carefully for signs of wear or 
 G-3 

damage, and correct any potentially hazardous conditions. Take steps to protect these supply lines from 

damage during use. 
 G-4 

Emergency Procedures:

 Always be familiar with emergency procedures BEFORE beginning an inspection. After an emergency has 

developed, crucial time can be lost if emergency procedures are not known. Be familiar with the procedures 

to follow in the event of an equipment malfunction or the development of a dangerous situation with the 

equipment or in the vicinity of the inspection site when operating specialized testing equipment. 

 Be familiar with the nature of any product being dispensed by a device or being used in or near the inspection 

area. Know the emergency procedures to be followed when a spill has occurred or a person has been exposed 

to the product. Knowledge of emergency procedures and related information should include the correct 

selection and use of fire extinguishers, the location of emergency shut-offs, and evacuation procedures. 

 Keep a list of emergency phone numbers handy at all times in a notebook or on a card. Examples of numbers 

to keep are the local fire department, emergency medical facility, and other appropriate public safety agencies. 

Eye Protection:

 Appropriate eye protection is recommended when working around hazardous products which may 

inadvertently splash into the eyes, and eye-wash facilities should be considered. Contact lens wearers should 

be particularly careful to follow the instructions of their eye-care practitioner and local OSHA representative 

when working around hazardous products. 

 Appropriate eye protection should also be worn when working in an area with overhead projections such as 

meat hooks or other sharp objects or where there is a potential of flying projectiles (e.g., when working near 

tools that grind, chip, etc.). 

Fire Extinguisher:

 Know the proper use and selection of fire extinguishers for a given application. Contact your local fire 

department for current information and training. 

First Aid Kit:

 An appropriate first aid kit or kits should be provided for every vehicle and in every laboratory. Consideration 

should be given to the type of work that the inspector, metrologist, or serviceperson typically performs and the 

types of hazards typically encountered in these types of activities. Items in addition to those contained in a 

basic first aid kit may need to be added to address the potential hazards which may be encountered by the 

person who will be most likely to use the first aid kit. Check with your local OSHA office or with your 

departmental safety officer for input on the items to be included in each kit. 

Grounding:

 It is essential to properly ground the prover being used when inspecting meters which dispense flammable 

products. Be sure to connect the grounding wire or jumper cable to bare metal surfaces, not to painted or 

plastic surfaces. 
 G-5 

 Retail Motor Fuel Dispensers: 

 When testing retail motor fuel dispensers, be sure to: 

 - Ground the nozzle against the prover neck when dispensing product. 

 - Ground the neck of the prover against the metal funnel when returning product to the 

storage tank. 

 - If a test measure is left on a cart when dispensing product or returning product to the storage 

tank, be sure the card is properly grounded. 

 Vehicle Mounted Tank, Loading Rack, or Wholesale Meters: 

 - Use a grounding wire, jumper cable, or terminal ground to ground the prover to the vehicle 

from which the product is obtained. 

 - Use a grounding wire, jumper cable, or terminal ground to ground the prover to the vehicle 

or tank when returning product to storage. 

 - These guidelines also apply when testing liquefied petroleum gas liquid-measuring devices. 

 Although these devices are tested as a "closed system", the possibility of leaks is always 

present and can present a potential hazard. 

 - Always ground yourself to an above ground storage tank before climbing onto the tank by 

touching the tank or the hand rails. 

Ignition Sources:

 Combustion can result when an ignition source is present and fuel and oxygen are also available. It is 

necessary to avoid possible sources of ignition when testing meters which dispense petroleum products or 

other flammable materials. Possible sources of ignition include, but are not limited to: open flames or 

smoking, metal to metal contact which causes sparking (e.g., metal wrench or hammer on a pipe fitting), a 

running motor, static discharge, worn or faulty electrical wiring, improper grounding, and the wearing of 

synthetic clothing. Also be sure that provers and other test equipment are equipped with explosion-proof 

motors. If ignition sources cannot be eliminated at the time of the inspection, it is recommended that the 

testing procedure be discontinued until the hazardous conditions are corrected. 

 Because disposable lighters can spark upon impact, the inspector should avoid carrying a lighter in his or her 

front shirt pocket. 

 ALWAYS USE A METAL FUNNEL TO RETURN PRODUCT TO PRODUCT STORAGE TANKS. 

NEVER USE A PLASTIC SAFETY CONE AS A FUNNEL!! Pouring product into the return fill can build 

up static electricity; a proper ground must be made by placing the metal neck of the prover against the metal 

lip of the funnel. 

Lifting:

 Be familiar with and use proper lifting techniques when lifting test weights or heavy equipment to prevent 

personal injury. To reduce the possibility of back injury, use equipment which would decrease the amount of 

lifting required whenever possible (For example: an extended height funnel, carts for transporting weights, 

platforms suspended from monorail scales instead of overhead meat hooks, etc.). 

 Periodic training in proper lifting techniques is encouraged. 
 G-6 

Location:

 Carefully examine the inspection site prior to beginning an inspection and testing procedure. Look for 

potentially dangerous situations such as wet areas which may be slippery (see also Wet/Slick Conditions), the 

use or presence of hazardous and/or flammable materials and any spillage or leakage of these products (see 

also Chemicals, Petroleum Products, and Hazardous Materials), adjacent activities which may contribute 

a potential hazard to the inspection (e.g., welding near the inspection area would provide a potential ignition 

source when testing devices which dispense flammable liquids), obstructions in the area which may prove to 

be safety hazards (e.g., objects on the ground which the inspector might trip over, objects in the path of the 

inspector to and from the device being tested, exits blocked by test equipment or vehicles, etc. -- see also 

Obstructions), pedestrian or vehicle traffic (see also Traffic), steep or narrow stairways, overhead hazards 

(e.g., feed bins, loading rack equipment, low-hanging beams in feed mills and warehouses, overhead activities, 

low doorways, etc. -- see also Overhead Hazards), lack of or defective handrails, and loose or exposed 

wiring (see also Electrical Hazards). Use great care when moving around and working in areas in which 

these potential hazards are present. When using flammable products (e.g., testing metering devices), note the 

location of the fire extinguisher, emergency shut-offs, etc. prior to beginning the inspection. 

Material Safety Data Sheets (MSDS):

 MSDS's are provided by the manufacturer of a product to identify the product's basic characteristics and 

hazardous information. MSDS's typically provide information pertaining to the characteristics of a product 

such as hazardous ingredients, physical data, fire and explosion hazard information, health hazard information, 

reactivity data, spill or leak procedures, special protection information, special precautions, toxicological 

information, and other relevant information. MSDS's can be obtained from the manufacturer of the product. 

As new information is discovered concerning the properties of a product and the effects of various levels of 

exposure to it, MSDS's can change. It is recommended that updated versions of the MSDS's be obtained on at 

least an annual basis. For further information on MSDS's, contact your local OSHA office. 

Nature of Product:

 Be knowledgeable about the nature of the product being dispensed by a device prior to beginning a test on the 

device. For all hazardous materials it is recommended that a copy of the Material Safety Data Sheet (MSDS) 

be obtained for that product and reviewed prior to testing the device. Carefully read and follow the 

instructions on any warning labels posted on the device or affixed to a packaged product for precautions 

which should be taken when working around the product. 

Obstructions:

 Care should be taken to avoid injury from obstructions in the work area during the course of an inspection. 

Obstructions which might prove to be safety hazards include objects on the ground which the inspector might 

trip over, objects in the path of the inspector to and from the device being tested, steep or narrow stairways, 

exits blocked by test equipment or vehicles, etc. 

Overhead Hazards:

 Note any overhead hazards such as feed bins, loading rack equipment, low-hanging beams in feed mills and 

warehouses, activities overhead, and low doorways prior to the inspection. Take precautions (such as wearing 
 G-7 

a hardhat) to avoid potential injuries as the situation dictates. 

Personal Protection Equipment:

 Included among the many types of personal protection equipment which is available are items such as nonsynthetic clothing, coveralls, gloves, barrier cream, non-permeable safety aprons, safety sleeves, safety shoes, 

respirators, goggles or safety glasses, hearing protection, and hardhats. OSHA and safety-clothing and safetyequipment manufacturers can provide additional information concerning the selection of personal protection 

equipment for a given type of inspection activity. 

 Before providing personal protection equipment (PPE), management should determine whether or not PPE is 

actually required for a particular inspection activity. If it is determined that an employee is exposed to a 

hazard, the management should first try to minimize the hazard by examining and modifying work methods 

and conditions. If it is determined that the employee is still exposed to the hazard after modifying work 

methods and conditions, consideration should be given to purchasing PPE. It should be realized that certain 

types of PPE such as respirators can require employee physicals and extensive ongoing training and 

maintenance; failure to follow these requirements may render the PPE ineffective or even dangerous. 

Safety Shoes:

 Safety shoes are recommended to be worn when performing certain weights and measures activities to prevent 

personal injury. Safety shoes are available to prevent possible injury to the foot from falling weights or 

equipment and also to provide protection from slippage and static discharge. Many styles and types of safety 

shoes are available. The American National Standards Institute and safety-shoe manufacturers can provide 

additional information concerning the selection of safety shoes for different types of inspection activities. 

Safety Cones/Warning Signs:

 Safety warning signs or safety cones should be positioned to block off the work area when the inspection site 

is exposed to vehicular or pedestrian traffic . These precautions should also be taken when working around 

flammable liquids to warn people of a potential hazard; in this instance, it is also recommended that "No 

Smoking" and "No Open Flame" signs be posted. 

Static Discharge:

 Combustion can result when an ignition source is present and fuel and oxygen are also available. Sources 

of static discharge introduce the potential of an ignition source into the testing area. Avoid all sources of static 

discharge when testing flammable products. 

Support:

 Scales: Be certain that the installation is adequate to support the scale, test weights equal to the capacity 

of the scale, and any weight carts, test platforms, platters, chains, hooks, or other accessories 

used to suspend or support the test weights prior to proceeding with a testing procedure. Any 

test platforms, platters, chains, hooks, or other accessories must be capable of supporting the test 

weights necessary for the inspection. 

 Meters: Be sure the inspection site surface is rigid enough to support the weight of a large volume prover 
 G-8 

when the prover is filled with the test liquid. Chocks should be used to secure the wheels of the 

prover during the testing procedure. 

Switch Loading:

 Do not use a test measure that has been used for drafts of gasoline to measure diesel fuel until you are certain 

that all gasoline vapors have dissipated. This practice, called "switch-loading" is extremely hazardous because 

diesel fuel is likely to produce a static charge while being dispensed. Sparks from this charge could easily 

ignite gasoline vapors inside the measure. 

Traffic:

 Be aware of vehicular and pedestrian traffic patterns in and around the inspection site. Mark the test spot 

appropriately by using safety cones, flags, etc. 

Transportation of Equipment:

 Consideration must be given to isolating the inspector/serviceperson from weighing and measuring equipment 

during the transportation of the equipment to and from the work site. The inspector/serviceperson must be 

isolated from hazardous fumes; means of such isolation include, but are not limited to, vehicles outfitted with 

protective barriers; equipment carriers located outside of the vehicle; vehicles with separate driver/equipment 

compartments, etc. 

 All equipment must be properly secured to avoid exposing the inspector/serviceperson to the potential of 

flying projectiles. 

Wet/Slick Conditions:

 Caution should be exercised when working in wet, slippery, or icy conditions to avoid slipping or possible 

injury from electrical sources. Shoes with non-skid soles should be worn to provide adequate traction to 

prevent slipping. 

 Absorbent material should be used on any product spills to prevent possible injury due to slipping on a slick 

surface.