Handbook 44 – 2022 3.31. Vehicle-Tank Meters

3-29

This publication is available free of charge from: https://doi.org/10.6028/NIST.HB.44-2022

Table of Contents

Page

Section 3.31. Vehicle-Tank Meters ....................................................................................... 3-31

A. Application ...................................................................................................................................................3-31

A.1. General................................................................................................................................................3-31

A.2. Exceptions...........................................................................................................................................3-31

A.3. Additional Code Requirements...........................................................................................................3-31

S. Specifications................................................................................................................................................3-31

S.1. Design of Indicating and Recording Elements and of Recorded Representations. .............................3-31

S.1.1. Primary Elements..................................................................................................................3-31

S.1.2. Graduations...........................................................................................................................3-32

S.1.3. Indicators. .............................................................................................................................3-33

S.1.4. Computing-Type Device.......................................................................................................3-33

S.2. Design of Measuring Elements...........................................................................................................3-34

S.2.1. Air/Vapor Elimination. .........................................................................................................3-34

S.2.2. Provision for Sealing.............................................................................................................3-34

S.2.3. Directional Flow Valves. ......................................................................................................3-35

S.2.4. Zero-Set-Back Interlock, Vehicle-Tank Meters, Electronic. .................................................3-35

S.2.5. Automatic Temperature Compensation for Refined Petroleum Products.............................3-35

S.2.6. Thermometer Well, Temperature Determination..................................................................3-36

S.3. Design of Discharge Lines and Discharge Line Valves......................................................................3-36

S.3.1. Diversion of Measured Liquid. .............................................................................................3-36

S.3.2. Pump-Discharge Unit............................................................................................................3-37

S.3.3. Gravity-Discharge Unit.........................................................................................................3-37

S.3.4. Discharge Hose.....................................................................................................................3-37

S.3.5. Discharge Valve....................................................................................................................3-37

S.3.6. Antidrain Valve.....................................................................................................................3-37

S.4. Design of Intake Lines (for Milk-Metering Systems).........................................................................3-38

S.4.1. Diversion of Liquid to be Measured. ....................................................................................3-38

S.4.2. Intake Hose. ..........................................................................................................................3-38

S.5. Marking Requirements........................................................................................................................3-38

S.5.1. Limitation of Use. .................................................................................................................3-38

S.5.2. Discharge Rates. ...................................................................................................................3-38

S.5.3. Measuring Components, Milk-Metering System..................................................................3-38

S.5.4. Flood Volume, Milk-Metering System.................................................................................3-38

S.5.5. Conversion Factor.................................................................................................................3-38

S.5.6. Temperature Compensation for Refined Petroleum Products...............................................3-38

N. Notes..............................................................................................................................................................3-39

N.1. Test Liquid..........................................................................................................................................3-39

N.2. Evaporation and Volume Change. ......................................................................................................3-39

N.3. Test Drafts...........................................................................................................................................3-39

N.4. Testing Procedures..............................................................................................................................3-39

N.4.1. Normal Tests.........................................................................................................................3-39

N.4.2. Special Tests (Except Milk-Measuring Systems). ................................................................3-39

N.4.3. Antidrain Valve Test.............................................................................................................3-40

N.4.4. System Capacity. ..................................................................................................................3-40

N.4.5. Product Depletion Test. ........................................................................................................3-40

N.4.6. Verification of Linearization Factors....................................................................................3-40

N.4.7. Repeatability Tests................................................................................................................3-40
3.31. Vehicle-Tank Meters Handbook 44 – 2022

3-30

This publication is available free of charge from: https://doi.org/10.6028/NIST.HB.44-2022

N.5. Temperature Correction for Refined Petroleum Products..................................................................3-40

T. Tolerances.....................................................................................................................................................3-40

T.1. Application..........................................................................................................................................3-40

T.1.1. To Underregistration and to Overregistration. ......................................................................3-40

T.2. Tolerance Values. ...............................................................................................................................3-40

T.2.1. Automatic Temperature-Compensating Systems..................................................................3-42

T.3. Repeatability. ......................................................................................................................................3-42

T.4. Product Depletion Test. ......................................................................................................................3-42

UR. User Requirements ......................................................................................................................................3-42

UR.1. Installation Requirements. ..................................................................................................................3-42

UR.1.1. Discharge Rate......................................................................................................................3-42

UR.1.2. Unit Price. .............................................................................................................................3-42

UR.1.3. Intake Hose. ..........................................................................................................................3-42

UR.1.4. Liquid Measured...................................................................................................................3-42

UR.2. Use Requirements. ..............................................................................................................................3-43

UR.2.1. Return of Indicating and Recording Elements to Zero. ........................................................3-43

UR.2.2. Ticket Printer, Customer Ticket............................................................................................3-43

UR.2.3. Ticket in Printing Device......................................................................................................3-43

UR.2.4. Credit for Flood Volume.......................................................................................................3-43

UR.2.5. Automatic Temperature Compensation for Refined Petroleum Products.............................3-43

UR.2.6. Clearing the Discharge Hose.................................................................................................3-43

UR.3. Maintenance Requirements.................................................................................................................3-44

UR.3.1. Use of Adjustments...............................................................................................................3-44
Handbook 44 – 2022 3.31. Vehicle-Tank Meters

3-31

This publication is available free of charge from: https://doi.org/10.6028/NIST.HB.44-2022

Section 3.31. Vehicle-Tank Meters

A. Application

A.1. General. – This code applies to meters mounted on vehicle tanks including those used for the measurement 

and delivery of petroleum products or agri-chemical liquids such as fertilizers, feeds, pesticides, defoliants, and bulk 

deliveries of water.

(Amended 1985 and 1995)

A.2. Exceptions. – This code does not apply to the following devices:

(a) Devices used for dispensing liquefied petroleum gases, or other liquids that do not remain in a liquid state at 

atmospheric pressures and temperatures. (Also see Section 3.32. Code for Liquefied Petroleum Gas and 

Anhydrous Ammonia Liquid-Measuring Devices.)

(b) Devices used solely for dispensing a product in connection with operations in which the amount dispensed 

does not affect customer charges.

(c) Vehicle tanks used as measures. (Also see Section 4.40. Code for Vehicle Tanks Used as Measures.)

(d) Mass flow meters. (Also see Section 3.37. Code for Mass Flow Meters.)

(Added 1994)

(e) Devices used to measure cryogenic liquids. (Also see Section 3.34. Code for Cryogenic Liquid-Measuring 

Devices.)

(f) Devices used to measure carbon dioxide liquids. (Also see Section 3.38. Code for Carbon Dioxide 

Liquid-Measuring Devices.)

A.3. Additional Code Requirements. – In addition to the requirements of this code, Vehicle-Tank Meters shall 

meet the requirements of 1.10. General Code requirements.

S. Specifications

S.1. Design of Indicating and Recording Elements and of Recorded Representations.

S.1.1. Primary Elements.

S.1.1.1. General. – A meter shall be equipped with a primary indicating element and may also be equipped 

with a primary recording element.

Note: Except for systems used solely for the sale of aviation fuel into aircraft and for aircraft-related operations, vehicletank meters shall be equipped with a primary recording element as required by paragraph UR.2.2. Ticket Printer; 

Customer Ticket.

(Amended 1993)

S.1.1.2. Units.

(a) A meter shall indicate, and record if the meter is equipped to record, its deliveries in terms of liters 

or gallons. Fractional parts of the liter or gallon shall be in terms of either decimal or binary 

subdivisions.
3.31. Vehicle-Tank Meters Handbook 44 – 2022

3-32

This publication is available free of charge from: https://doi.org/10.6028/NIST.HB.44-2022

(b) When it is an industry practice to purchase and sell milk by weight based upon 1.03 kg/L (8.6 lb/gal), 

the primary indicating element may indicate in kilograms or pounds and decimal kilograms or 

pounds. The weight value division shall be a decimal multiple or submultiple of 1, 2, or 5. (Also 

see Section S.5.5. Conversion Factor.)

S.1.1.3. Value of Smallest Unit. – The value of the smallest unit of indicated delivery, and recorded 

delivery if the meter is equipped to record, shall not exceed the equivalent of:

(a) 0.5 L (0.1 gal) or 0.5 kg (1 lb) on milk-metering systems;

(b) 0.5 L (0.1 gal) on meters with a rated maximum flow rate of 750 L/min (200 gal/min) or less;

(c) 5 L (1 gal) on meters with a rated maximum flow of 375 L/min (100 gal/min) or more used for jet 

fuel aviation refueling systems; or

(Added 2006)

(d) 5 L (1 gal) on other meters.

(Amended 1989, 1994 and 2006)

S.1.1.4. Advancement of Indicating and Recording Elements. – Primary indicating and recording 

elements shall be susceptible to advancement only by the mechanical operation of the meter. However, a 

meter may be cleared by advancing its elements to zero, but only if:

(a) the advancing movement, once started, cannot be stopped until zero is reached; or

(b) in the case of indicating elements only, such elements are automatically obscured until the elements 

reach the correct zero position.

S.1.1.5. Return to Zero. – Primary indicating elements shall be readily returnable to a definite zero 

indication. Means shall be provided to prevent the return of primary indicating elements, and of primary 

recording elements if these are returnable to zero, beyond their correct zero position. Primary indicating 

elements shall not be resettable to zero during a delivery.

(Amended 2016)

S.1.2. Graduations.

S.1.2.1. Length. – Graduations shall be so varied in length that they may be conveniently read.

S.1.2.2. Width. – In any series of graduations, the width of a graduation shall in no case be greater than 

the width of the minimum clear interval between graduations, and the width of main graduations shall be not 

more than 50 % greater than the width of subordinate graduations. Graduations shall in no case be less than 

0.2 mm (0.008 in) wide.

S.1.2.3. Clear Interval Between Graduations. – The clear interval shall be not less than 2.5 mm 

(0.10 in). If the graduations are not parallel, the measurement shall be made:

(a) along the line of relative movement between the graduations at the end of the indicator; or

(b) if the indicator is continuous, at the point of widest separation of the graduations.

(Amended 1986)
Handbook 44 – 2022 3.31. Vehicle-Tank Meters

3-33

This publication is available free of charge from: https://doi.org/10.6028/NIST.HB.44-2022

S.1.3. Indicators.

S.1.3.1. Symmetry. – The index of an indicator shall be symmetrical with respect to the graduations at 

least throughout that portion of its length associated with the graduations.

S.1.3.2. Length. – The index of an indicator shall reach to the finest graduations with which it is used, 

unless the indicator and the graduations are in the same plane, in which case the distance between the end of 

the indicator and the ends of the graduations, measured along the line of the graduations, shall be not more 

than 1.0 mm (0.04 in).

S.1.3.3. Width. – The width of the index of an indicator in relation to the series of graduations with which 

it is used shall be not greater than:

(a) the width of the narrowest graduation;* and

[*Nonretroactive as of January 1, 2002]

(Amended 2001)

(b) the width of the minimum clear interval between graduations.

When the index of an indicator extends along the entire length of a graduation, that portion of the index of 

the indicator that may be brought into coincidence with the graduation shall be of the same width throughout 

the length of the index that coincides with the graduation.

S.1.3.4. Clearance. – The clearance between the index of an indicator and the graduations shall in no case 

be more than 1.5 mm (0.06 in).

S.1.3.5. Parallax. – Parallax effects shall be reduced to the practicable minimum.

S.1.3.6. Travel of Indicator. – If the most sensitive element of the primary indicating element utilizes an 

indicator and graduations, the relative movement of these parts corresponding to the smallest indicated value 

shall not be less than 5 mm (0.20 in).

S.1.4. Computing-Type Device.

S.1.4.1. Display of Unit Price. – In a device of the computing type, means shall be provided for 

displaying, in a manner clear to the operator and an observer, the unit price at which the device is set to 

compute. The unit price is not required to be displayed continuously.

(Amended 1983 and 2005)

S.1.4.2. Printed Ticket. – If a computing-type device issues a printed ticket which displays the total 

computed price, the ticket shall also have printed clearly thereon the total quantity of the delivery, the 

appropriate fraction of the quantity, and the price per unit of quantity.

(Amended 1989)

S.1.4.3. Money-Value Computations. – Money-value computations shall be of the full-computing type 

in which the money-value at a single unit price, or at each of a series of unit prices, shall be computed for 

every delivery within either the range of measurement of the device or the range of the computing elements, 

whichever is less. Value graduations shall be supplied and shall be accurately positioned. The value of each 

graduated interval shall be one cent. On electronic devices with digital indications, the total price may be 

computed on the basis of the quantity indicated when the value of the smallest division indicated is equal to 

or less than 0.2 L (0.1 gal) or 0.2 kg (1 lb).

(Amended 1979 and 1989)
3.31. Vehicle-Tank Meters Handbook 44 – 2022

3-34

This publication is available free of charge from: https://doi.org/10.6028/NIST.HB.44-2022

S.1.4.4. Money-Values, Mathematical Agreement. – Any digital money-value indication and any 

recorded money-value on a computing-type device shall be in mathematical agreement with its associated 

quantity indication or representation to within one cent of money-value.

S.2. Design of Measuring Elements.

S.2.1. Air/Vapor Elimination. – A measuring system shall be equipped with an effective air/vapor eliminator 

or other automatic means to prevent the passage of air/vapor through the meter. Vent lines from the air/vapor 

eliminator shall be made of appropriate non-collapsible material.

(Amended 1993 and 2017)

S.2.2. Provision for Sealing. – For devices and systems in which the configuration or calibration parameters 

can be changed by use of a removable digital storage device, security shall be provided for those parameters as 

specified in G-S.8.2. Devices and Systems Adjusted Using Removable Digital Storage Devices. For parameters 

adjusted using other means, the following applies.

Adequate provision shall be made for an approved means of security (e.g., data change audit trail) or for 

physically applying a security seal in such a manner that requires the security seal to be broken before a change 

or an adjustment or interchange can be made of:

(a) any measuring or indicating element;

(b) any adjustable element for controlling delivery rate when such rate tends to affect the accuracy of 

deliveries; and

(c) any metrological parameter that will affect the metrological integrity of the device or system.

When applicable, the adjusting mechanism shall be readily accessible for purposes of affixing a security seal.

Audit trails shall use the format set forth in Table S.2.2. Categories of Device and Methods Sealing.*

[*Nonretroactive as of January 1, 1995]

(Amended 2006 and 2019)
Handbook 44 – 2022 3.31. Vehicle-Tank Meters

3-35

This publication is available free of charge from: https://doi.org/10.6028/NIST.HB.44-2022

Table S.2.2. 

Categories of Device and Methods of Sealing

Categories of Device Methods of Sealing

Category 1: No remote configuration capability. Seal by physical seal or two event counters: one for

calibration parameters and one for configuration 

parameters.

Category 2: Remote configuration capability, but access is 

controlled by physical hardware.

The device shall clearly indicate that it is in the remote 

configuration mode and record such message if capable of 

printing in this mode or shall not operate while in this 

mode.

The hardware enabling access for remote communication 

must be on-site. The hardware must be sealed using a 

physical seal or an event counter for calibration 

parameters and an event counter for configuration 

parameters. The event counters may be located either at 

the individual measuring device or at the system 

controller; however, an adequate number of counters must 

be provided to monitor the calibration and configuration 

parameters of the individual devices at a location. If the 

counters are located in the system controller rather than 

at the individual device, means must be provided to 

generate a hard copy of the information through an on-site 

device.

Category 3: Remote configuration capability access may 

be unlimited or controlled through a software switch (e.g., 

password).

The device shall clearly indicate that it is in the remote 

configuration mode and record such message if capable of 

printing in this mode or shall not operate while in this 

mode.

An event logger is required in the device; it must include 

an event counter (000 to 999), the parameter ID, the date 

and time of the change, and the new value of the 

parameter. A printed copy of the information must be 

available on demand through the device or through 

another on-site device. The information may also be 

available electronically. The event logger shall have a 

capacity to retain records equal to 10 times the number of 

sealable parameters in the device, but not more than 

1000 records are required. (Note: Does not require 

1000 changes to be stored for each parameter.)

[Nonretroactive as of January 1, 1995]

(Table Added 2006) (Amended 2016)

S.2.3. Directional Flow Valves. – Valves intended to prevent reversal of flow shall be automatic in operation. 

However, on equipment used exclusively for fueling aircraft, such valves may be manual in operation.

S.2.4. Zero-Set-Back Interlock, Vehicle-Tank Meters, Electronic. – Except for vehicle-mounted metering 

systems used solely for the delivery of aviation fuel, a device shall be so constructed that after individual or 

multiple deliveries at one location have been completed, an automatic interlock system shall engage to prevent a 

subsequent delivery until the indicating and, if equipped, recording elements have been returned to their zero 

position. For individual deliveries, if there is no product flow for three minutes the transaction must be completed 

before additional product flow is allowed. The three-minute timeout shall be a sealable feature of an indicator.

[Nonretroactive as of January 1, 2006]

(Added 2005)

S.2.5. Automatic Temperature Compensation for Refined Petroleum Products.

S.2.5.1. Automatic Temperature Compensation for Refined Petroleum Products. – A device may be 

equipped with an automatic means for adjusting the indication and registration of the measured volume of 

product to the volume at 15 °C for liters or the volume at 60 °F for gallons and decimal subdivisions or 

fractional equivalents thereof where not prohibited by state law.
3.31. Vehicle-Tank Meters Handbook 44 – 2022

3-36

This publication is available free of charge from: https://doi.org/10.6028/NIST.HB.44-2022

S.2.5.2. Provision for Deactivating. – On a device equipped with an automatic temperaturecompensating mechanism that will indicate or record only in terms of liters compensated to 15°C or gallons 

compensated to 60 °F, provision shall be made for deactivating the automatic temperature-compensating 

mechanism so the meter can indicate and record, if it is equipped to record, in terms of the uncompensated 

volume.

S.2.5.3. Gross and Net Indications. – A device equipped with automatic temperature compensation shall 

indicate or record, if equipped to record, both the gross (uncompensated) and net (compensated) volume for 

testing purposes. It is not necessary that both net and gross volume be displayed simultaneously.

S.2.5.4. Provision for Sealing Automatic Temperature-Compensating Systems. – Adequate provision 

shall be made for an approved means of security (e.g., data change audit trail) or physically applying security 

seals in such a manner that an automatic temperature-compensating system cannot be disconnected and no 

adjustment may be made to the system.

S.2.5.5. Temperature Determination with Automatic Temperature Compensation. – For test 

purposes, means shall be provided (e.g., thermometer well) to determine the temperature of the liquid either:

(a) in the liquid chamber of the meter; or

(b) immediately adjacent to the meter in the meter inlet or discharge line.

(Added 2007)

S.2.6. Thermometer Well, Temperature Determination. – For test purposes, means shall be provided (e.g., 

thermometer well) to determine the temperature of the liquid either in the:

(a) liquid chamber of the meter; or 

(b) meter inlet or discharge line immediately adjacent to the meter.

[Nonretroactive as of January 1, 2012)

(Added 2011)

S.3. Design of Discharge Lines and Discharge Line Valves.

(Not applicable to milk-metering systems.)

S.3.1. Diversion of Measured Liquid. – No means shall be provided by which any measured liquid can be 

diverted from the measuring chamber of the meter or the discharge line thereof. However, two or more delivery 

outlets may be installed if means are provided to ensure that:

(a) liquid can flow from only one such outlet at one time; and

(b) the direction of flow for which the mechanism may be set at any time is definitely and conspicuously 

indicated.

This paragraph does not apply to the following:

(1) Equipment used exclusively for fueling aircraft.

(2) Multiple-product, single-discharge hose metering systems that are equipped with systems designed to 

flush the discharge hose, provided the flushing system complies with the provisions of paragraph S.3.1.1. 

Means for Clearing the Discharge Hose.

(Amended 2018)
Handbook 44 – 2022 3.31. Vehicle-Tank Meters

3-37

This publication is available free of charge from: https://doi.org/10.6028/NIST.HB.44-2022

S.3.1.1. Means for Clearing the Discharge Hose. – Metering systems may be equipped with systems 

specifically designed to facilitate clearing of the discharge hose prior to delivery to avoid product 

contamination. In such systems, a valve to temporarily divert product from the measuring chamber of the 

meter to a storage tank shall be installed only if all the following are met:

(a) the discharge hose remains of the wet hose type; 

(b) the valve and associated piping are approved by the weights and measures authority having 

jurisdiction over the system prior to commercial use;

(c) the valve is permanently marked with its purpose (e.g., flush valve);

(d) the valve is installed in a conspicuous manner and as far from the hose reel as practical; 

(e) the system clearly and automatically indicates the direction of product flow during operation of the 

flush system; 

(f) clear means, such as an indicator light or audible alarm, is used to identify when the valve is in use; 

and

(g) no hoses or piping are connected to the inlet when it is not in use.

(Added 2018)

S.3.2. Pump-Discharge Unit. – On a pump-discharge unit, the discharge hose shall be of the wet-hose type 

with a shutoff valve at its outlet end. However, a pump-discharge unit may be equipped also with a dry-hose 

without a shutoff valve at its outlet end, but only if:

(a) the dry-hose is as short as practicable; and

(b) there is incorporated in the discharge piping, immediately adjacent to the meter, effective means to 

ensure that liquid can flow through only one of the discharge hoses at any one time and that the meter 

and the wet-hose remain full of liquid at all times.

S.3.3. Gravity-Discharge Unit. – On a gravity-discharge unit, the discharge hose or equivalent pipe shall be 

of the dry-hose type with no shutoff valve at its outlet end. The dry-hose shall be of such stiffness and only of 

such length as to facilitate its drainage. The inlet end of the hose or of an equivalent outlet pipe shall be of such 

height as to provide for proper drainage of the hose or pipe. There shall be incorporated an automatic vacuum 

breaker or equivalent means to prevent siphoning and to ensure the rapid and complete drainage.

S.3.4. Discharge Hose. – A discharge hose shall be adequately reinforced.

S.3.5. Discharge Valve. – A discharge valve may be installed in the discharge line only if the device is of the 

wet-hose type, in which case such valve shall be at the discharge end of the line. Any other shutoff valve on the 

discharge side of the meter shall be of the automatic or semiautomatic predetermined-stop type or shall be 

operable only:

(a) by means of a tool (but not a pin) entirely separate from the device; or

(b) by mutilation of a security seal with which the valve is sealed open.

S.3.6. Antidrain Valve. – In a wet-hose, pressure-type device, an effective antidrain valve shall be 

incorporated in the discharge valve or immediately adjacent thereto. The antidrain valve shall function so as to 

prevent the drainage of the discharge hose. However, a device used exclusively for fueling and defueling aircraft 

may be of the pressure type without an antidrain valve.
3.31. Vehicle-Tank Meters Handbook 44 – 2022

3-38

This publication is available free of charge from: https://doi.org/10.6028/NIST.HB.44-2022

S.4. Design of Intake Lines (for Milk-Metering Systems).

S.4.1. Diversion of Liquid to be Measured. – No means shall be provided by which any liquid can be diverted 

from the supply tank to the receiving tank without being measured by the device.

S.4.2. Intake Hose. – The intake hose shall be:

(a) of the dry-hose type;

(b) adequately reinforced;

(c) not more than 6 m (20 ft) in length, unless it can be demonstrated that a longer hose is essential to permit 

pickups from a supply tank; and

(d) connected to the pump at horizontal or above, to permit complete drainage of the hose.

S.5. Marking Requirements.

S.5.1. Limitation of Use. – If a meter is intended to measure accurately only liquids having particular 

properties, or to measure accurately only under specific installation or operating conditions, or to measure 

accurately only when used in conjunction with specific accessory equipment, these limitations shall be clearly 

and permanently stated on the meter.

S.5.2. Discharge Rates. – A meter shall be marked to show its designed maximum and minimum discharge 

rates. However, the minimum discharge rate shall not exceed 20 % of the maximum discharge rate.

Note: Also see example in Section 3.30. Liquid-Measuring Devices Code, paragraph S.4.4.1. Discharge Rates.

(Added 2003)

S.5.3. Measuring Components, Milk-Metering System. – All components that affect the measurement of 

milk that are disassembled for cleaning purposes shall be clearly and permanently identified with a common serial 

number.

S.5.4. Flood Volume, Milk-Metering System. – When applicable, the volume of product necessary to flood 

the system when dry shall be clearly, conspicuously, and permanently marked on the air eliminator.

S.5.5. Conversion Factor. – When the conversion factor of 1.03 kg/L (8.6 lb/gal) is used to convert the volume 

of milk to weight, the conversion factor shall be clearly marked on the primary indicating element and recorded 

on the delivery ticket.

(Added 1989)

S.5.6. Temperature Compensation for Refined Petroleum Products. – If a device is equipped with an 

automatic temperature compensator, the primary indicating elements, recording elements, and recorded 

representations shall be clearly and conspicuously marked to show the volume delivered has been adjusted to the 

volume at 15 °C for liters or the volume at 60 °F for gallons and decimal subdivisions or fractional equivalents 

thereof.

(Added 2007)
Handbook 44 – 2022 3.31. Vehicle-Tank Meters

3-39

This publication is available free of charge from: https://doi.org/10.6028/NIST.HB.44-2022

N. Notes

N.1. Test Liquid.

(a) A measuring system shall be tested with the liquid to be commercially measured or with a liquid of the same 

general physical characteristics. Following a satisfactory examination, the weights and measures official 

should attach a seal or tag indicating the product used during the test.

(Amended 1975)

(b) A milk-measuring system shall be tested with the type of milk to be measured when the accuracy of the 

system is affected by the characteristics of milk (e.g., positive displacement meters).

(Added 1989)

(Amended 1975 and 1989)

N.2. Evaporation and Volume Change. – Care shall be exercised to reduce to a minimum, evaporation losses and 

volume changes resulting from changes in temperature of the test liquid.

N.3. Test Drafts. – Test drafts should be equal to at least the amount delivered by the device in 1 minute at its 

maximum discharge rate and shall in no case be less than 180 L (50 gal) or 225 kg (500 lb).

(Amended 1989)

N.4. Testing Procedures.

N.4.1. Normal Tests. – The “normal” test of a measuring system shall be made at the maximum discharge rate 

that may be anticipated under the conditions of the installation. Any additional tests conducted at flow rates down 

to and including one-half of the sum of the maximum discharge flow rate and the rated minimum discharge flow 

rate shall be considered normal tests.

(Amended 1992)

N.4.1.1. Milk Measuring System. – The “normal” test shall include a determination of the effectiveness 

of the air elimination system.

N.4.1.2. Automatic Temperature-Compensating Systems for Refined Petroleum Products. – On 

devices equipped with automatic temperature-compensating systems, normal tests shall be conducted:

(a) by comparing the compensated volume indicated or recorded to the actual delivered volume 

corrected to 15 °C for liters or 60 °F for gallons and decimal subdivisions or fractional equivalents 

thereof; and

(b) with the temperature-compensating system deactivated, comparing the uncompensated volume 

indicated or recorded to the actual delivered volume.

The first test shall be performed with the automatic temperature-compensating system operating in the 

“as-found” condition. On devices that indicate or record both the compensated and uncompensated volume 

for each delivery, the tests in (a) and (b) may be performed as a single test.

(Added 2007)

N.4.2. Special Tests (Except Milk-Measuring Systems). – “Special” tests shall be made to develop the 

operating characteristics of a measuring system and any special elements and accessories attached to or associated 

with the device. Any test except as set forth in N.4.1. Normal Tests and N.4.5. Product Depletion Test shall be 

considered a special test. Special tests of a measuring system shall be made at a minimum discharge rate of 20 % 

of the marked maximum discharge rate or at the minimum discharge rate marked on the device, whichever is less.

(Amended 1978 and 2005)
3.31. Vehicle-Tank Meters Handbook 44 – 2022

3-40

This publication is available free of charge from: https://doi.org/10.6028/NIST.HB.44-2022

N.4.3. Antidrain Valve Test. – The effectiveness of the antidrain valve shall be tested after the pump pressure 

in the measuring system has been released and a valve between the supply tank and the discharge valve is closed.

N.4.4. System Capacity. – The test of a milk-measuring system shall include the verification of the volume of 

product necessary to flood the system as marked on the air eliminator.

N.4.5. Product Depletion Test. – Except for vehicle-mounted metering systems used solely for the delivery of 

aviation fuel, the effectiveness of the vapor eliminator or vapor elimination means shall be tested by dispensing 

product at the normal flow rate until the product supply is depleted and continuing until the lack of fluid causes 

the meter indication to stop completely for at least 10 seconds. If the meter indication fails to stop completely for 

at least 10 seconds, continue to operate the system for 3 minutes. Finish the test by switching to another 

compartment with sufficient product to complete the test on a multi-compartment vehicle or by adding sufficient 

product to complete the test to a single compartment vehicle. When adding product to a single compartment 

vehicle, allow appropriate time for any entrapped vapor to disperse before continuing the test. Test drafts shall 

be of the same size and run at approximately the same flow rate.

(Added 2005)

N.4.6. Verification of Linearization Factors. – All enabled linearization factors shall be verified. The 

verification of enabled linearization factors shall be done through physical testing or a combination of physical 

testing and empirical analysis at the discretion of the official with statutory authority.

(Added 2016)

N.4.7. Repeatability Tests. – Tests for repeatability should include a minimum of three consecutive test drafts 

of approximately the same size and be conducted under controlled conditions where variations in factors such as 

temperature, pressure, and flow rate are reduced to the extent that they will not affect the results obtained. When 

conducting the tests, the flow rates shall be within the minimum and maximum discharge rates as marked by the 

manufacturer. For devices equipped with an automatic temperature compensator, the results shall be based on 

the uncompensated (gross) volume (e.g., with the temperature compensator deactivated).

(Amended 2019)

N.5. Temperature Correction for Refined Petroleum Products. – Corrections shall be made for any changes in 

volume resulting from the differences in liquid temperatures between the time of passage through the meter and the 

time of volumetric determination in the prover. When adjustments are necessary, appropriate petroleum 

measurement tables should be used.

(Added 2007)

T. Tolerances

T.1. Application.

T.1.1. To Underregistration and to Overregistration. – The tolerances hereinafter prescribed shall be applied 

to errors of underregistration and errors of overregistration.

T.2. Tolerance Values. – Tolerances shall be as shown in Table 1. Accuracy Classes and Tolerances for VehicleTank Meters Other Than Vehicle-Mounted Milk Meters and Table 2. Tolerances for Vehicle-Mounted Milk Meters.

(Amended 1995)
Handbook 44 – 2022 3.31. Vehicle-Tank Meters

3-41

This publication is available free of charge from: https://doi.org/10.6028/NIST.HB.44-2022

Table 1. 

Accuracy Classes and Tolerances for Vehicle-Tank Meters Other Than Vehicle-Mounted Milk Meters

Accuracy 

Class Application Acceptance Tolerance

Maintenance 

Tolerance

Special Test 

Tolerance

0.3

- Petroleum products delivered from large capacity 

(flow rates over 115 L/min or 30 gpm)** devices, 

including motor-fuel devices

- Heated products (other than asphalt) at temperatures

greater than 50 °C (122 °F)

- Asphalt at temperatures equal to or below 50 °C

(122 °F)

- All other liquids not shown in the table where the 

typical delivery is greater than 200 L (50 gal)

0.15 % 0.3 % 0.45 %

0.3A - Asphalt at temperatures greater than 50 °C (122 °F) 0.3 % 0.3 % 0.5 %

0.5*

- Petroleum products delivered from small capacity (at 

4 L/min (1 gpm) through 115 L/min or 30 gpm)** 

motor-fuel devices

- Agri-chemical liquids

- All other applications not shown in the table where the 

typical delivery is ≤ 200 L (50 gal)

0.3 % 0.5 % 0.5 %

1.1

- Petroleum products and other normal liquids from 

devices with flow rates** less than 4 L/min (1 gpm) 

and

- Devices designed to deliver less than 4 L (1 gal)

0.75 % 1.0 % 1.25 %

1.5 - Water Overregistration 1.5 % 1.5 % 1.5 %

Underregistration 1.5 % 1.5 % 5.0 %

* For 5 gal and 10 gal test drafts, the tolerances specified for Accuracy Class 0.5 in the table above do not apply. For 

these test drafts, the maintenance tolerances on normal and special tests for 5 gal and 10 gal test drafts are 6 in3 and 

11 in3, respectively. Acceptance tolerances on normal and special tests are 3 in3 and 5.5 in3.

** Flow rate refers to designed or marked maximum flow rate.

(Added 2002) (Amended 2013)

Table 2. 

Tolerances for Vehicle-Mounted Milk Meters

Indication

(gallons)

Maintenance Tolerance

(gallons)

Acceptance Tolerance

(gallons)

100 0.5 0.3

200 0.7 0.4

300 0.9 0.5

400 1.1 0.6

500 1.3 0.7

Over 500 Add 0.002 gallon per indicated 

gallon over 500

Add 0.001 gallon per indicated gallon 

over 500

(Added 1989)
3.31. Vehicle-Tank Meters Handbook 44 – 2022

3-42

This publication is available free of charge from: https://doi.org/10.6028/NIST.HB.44-2022

T.2.1. Automatic Temperature-Compensating Systems. – The difference between the meter errors

(expressed as a percentage) determined with and without the automatic temperature-compensating system 

activated shall not exceed:

(a) 0.2 % for mechanical automatic temperature-compensating systems; and

(b) 0.1 % for electronic automatic temperature-compensating systems.

The delivered quantities for each test shall be approximately the same size. The results of each test shall be within 

the applicable acceptance or maintenance tolerance.

(Added 2007) (Amended 2010)

T.3. Repeatability. – When multiple tests are conducted at approximately the same flow rate and draft size, the 

range of the test results for the flow rate shall not exceed 40 % of the absolute value of the maintenance tolerance and 

the results of each test shall be within the applicable tolerance. (Also see N.4.7. Repeatability Tests.)

(Added 1992) (Amended 2001, 2002, and 2019)

T.4. Product Depletion Test. – The difference between the test result for any normal test and the product depletion 

test shall not exceed 0.5 % of the volume delivered in one minute at the maximum flow rate marked on the meter for 

meters rated higher than 380 Lpm (100 gpm) or 0.6 % of the volume delivered in one minute at the maximum flow 

rate marked on the meter for meters rated 380 Lpm (100 gpm) or lower. Test drafts shall be of the same size and run 

at approximately the same flow rate.

Note: The result of the product depletion test may fall outside of the applicable test tolerance as specified in Table 1. Accuracy 

Classes and Tolerances for Vehicle-Tank Meters.

(Amended 2013)

UR. User Requirements

UR.1. Installation Requirements.

UR.1.1. Discharge Rate. – A meter shall be so installed that the actual maximum discharge rate will not exceed 

the rated maximum discharge rate. If necessary, means for flow regulation shall be incorporated in the 

installation, in which case this shall be fully effective and automatic in operation.

UR.1.2. Unit Price. – There shall be displayed on the face of a device of the computing type the unit price at 

which the device is set to compute.

UR.1.3. Intake Hose. – The intake hose in a milk-metering system shall be installed to permit complete 

drainage and ensure that all available product is measured following each pickup.

UR.1.4. Liquid Measured. – A vehicle-tank meter shall continue to be used to measure the same liquid or one 

with the same general physical properties as that used for calibration and weights and measures approval unless 

the meter is recalibrated with a different product and tested by a registered service agency or a weights and 

measures official and approved by the weights and measures jurisdiction having statutory authority over the 

device.

(Added 2003)
Handbook 44 – 2022 3.31. Vehicle-Tank Meters

3-43

This publication is available free of charge from: https://doi.org/10.6028/NIST.HB.44-2022

UR.2. Use Requirements.

UR.2.1. Return of Indicating and Recording Elements to Zero. – The primary indicating elements (visual), 

and the primary recording elements, when these are returnable to zero, shall be returned to zero immediately 

before each delivery is begun and after the pump has been activated and the product to be measured has been 

supplied to the measuring system.

(Amended 1981)

UR.2.2. Ticket Printer, Customer Ticket. – Vehicle-Mounted metering systems shall be equipped with a 

ticket printer which shall be used for all sales where product is delivered through the meter. A copy of the ticket 

issued by the device shall be left with the customer at the time of delivery or as otherwise specified by the 

customer.

(Added 1993) (Amended 1994)

UR.2.2.1. Exceptions for the Sale of Aviation Fuel. – The provisions of UR.2.2. Ticket Printer, 

Customer Ticket shall not apply to vehicle-mounted metering systems used solely for the delivery of aviation 

fuel into aircraft and for aircraft-related operations.

(Added 1999)

UR.2.3. Ticket in Printing Device. – A ticket shall not be inserted into a device equipped with a ticket printer 

until immediately before a delivery is begun, and in no case shall a ticket be in the device when the vehicle is in 

motion while on a public street, highway, or thoroughfare.

UR.2.4. Credit for Flood Volume. – The volume of product necessary to flood the system as marked on the 

air eliminator shall be individually recorded on the pickup ticket of each seller affected.

UR.2.5. Automatic Temperature Compensation for Refined Petroleum Products.

UR.2.5.1. When to be Used. – In a state that does not prohibit, by law or regulation, the sale of 

temperature-compensated product, a device equipped with an activated automatic-temperature compensator 

shall be connected, operable, and in use at all times. An electronic or mechanical automatic 

temperature-compensating device or system may not be removed or deactivated, nor may a compensated 

device be replaced with an uncompensated device or system, without the written approval of the responsible 

weights and measures jurisdiction.

Note: This requirement does not specify the method of sale for products measured through a meter.

(Amended 2009)

UR.2.5.2. Period of Use. – When fuel is bought or sold on an automatic temperature compensation basis, 

it shall be bought or sold using this basis over at least a consecutive 12-month period unless otherwise agreed 

to by both the buyer and seller in writing.

(Added 2009)

UR.2.5.3. Invoices. – An invoice based on a reading of a device that is equipped with an automatic 

temperature compensator shall show that the volume delivered has been adjusted to the volume at 15 °C for 

liters or the volume at 60 °F for gallons and decimal subdivisions or fractional equivalents thereof.

(Added 2007)

UR.2.6. Clearing the Discharge Hose. 

UR.2.6.1. Records. – Whenever, prior to delivery, a different product is pumped through the discharge 

hose to avoid contamination, a record including the date, time, original product, new product, and gallons 
3.31. Vehicle-Tank Meters Handbook 44 – 2022

3-44

This publication is available free of charge from: https://doi.org/10.6028/NIST.HB.44-2022

pumped shall be maintained. These records shall be kept for a period of 12 months and available for 

inspection by the weights and measures authority having jurisdiction over the system.

(Added 2018)

UR.3. Maintenance Requirements.

UR.3.1. Use of Adjustments. – Whenever a device is adjusted, all enabled linearization factors shall be 

verified to determine that the errors are in tolerance and any adjustments which are made shall be made so as to 

bring performance errors as close as practicable to zero value. The verification of enabled linearization factors 

shall be done through physical testing or a combination of physical testing and empirical analysis.

(Added 2016)