Handbook 44 – 2015 3.31. Vehicle-Tank Meters

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Table of Contents

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. .............................................................................................................................3-32

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

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

S.2.1. 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............................................................................................................3-36

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).........................................................................3-37

S.4.1. Diversion of Liquid to be Measured. ....................................................................................3-37

S.4.2. Intake Hose. ..........................................................................................................................3-37

S.5. Marking Requirements........................................................................................................................3-37

S.5.1. Limitation of Use. .................................................................................................................3-37

S.5.2. Discharge Rates. ...................................................................................................................3-37

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

S.5.7. Meter Size. ............................................................................................................................3-38

N. Notes............................................................................................................................................................. 3-38

N.1. Test Liquid..........................................................................................................................................3-38

N.2. Evaporation and Volume Change. ......................................................................................................3-38

N.3. Test Drafts...........................................................................................................................................3-38

N.4. Testing Procedures..............................................................................................................................3-38

N.4.1. Normal Tests.........................................................................................................................3-38

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

N.4.3. Antidrain Valve Test.............................................................................................................3-39

N.4.4. System Capacity. ..................................................................................................................3-39

N.4.5. Product Depletion Test. ........................................................................................................3-39

N.5. Temperature Correction for Refined Petroleum Products...................................................................3-39
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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..................................................................3-41

T.3. Repeatability. ......................................................................................................................................3-41

T.4. Product Depletion Test. ......................................................................................................................3-41

UR. User Requirements ..................................................................................................................................... 3-41

UR.1. Installation Requirements. ..................................................................................................................3-41

UR.1.1. Discharge Rate......................................................................................................................3-41

UR.1.2. Unit Price. .............................................................................................................................3-41

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

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

UR.2. Use Requirements. ..............................................................................................................................3-42

UR.2.1. Return of Indicating and Recording Elements to Zero. ........................................................3-42

UR.2.2. Ticket Printer, Customer Ticket............................................................................................3-42

UR.2.3. Ticket in Printing Device. .....................................................................................................3-42

UR.2.4. Credit for Flood Volume.......................................................................................................3-42

UR.2.5. Automatic Temperature Compensation for Refined Petroleum Products.............................3-42
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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, 

vehicle-tank 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.
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(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.

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)

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.
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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)

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.
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S.2. Design of Measuring Elements.

S.2.1. Vapor Elimination. – A metering system shall be equipped with an effective vapor or air eliminator 

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

vapor eliminator shall be made of metal tubing or some other suitable rigid material.

(Amended 1993)

S.2.2. Provision for Sealing. – 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 may 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)
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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 through the device or through another on-site 

device. 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)

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 an 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 3-minute timeout shall be a sealable feature on 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 
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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.

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. – Except on equipment used exclusively for fueling aircraft, 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 is 

provided to insure 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.

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

insure 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.

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)
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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)

S.5.7. Meter Size. – Except for milk meters, if the meter model identifier does not provide a link to the meter 

size (in terms of pipe diameter) on an NTEP Certificate of Conformance, the meter shall be marked to show 

meter size.

[Nonretroactive as of January 1, 2009]

(Added 2008)

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)
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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. 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.

(Added 2001)

N.4.1.3. 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)

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.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)
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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 and Table 2. Tolerances for Vehicle-Mounted Milk Meters.

(Amended 1995)

Table 1. 

Accuracy Classes and Tolerances for Vehicle-Tank 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 in3and 

11 in3, respectively. Acceptance tolerances on normal and special tests are 3 in3and 5.5 in3.

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

(Added 2002) (Amended 2013)
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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)

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

(expressed as a percentage) for results 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.4.1.2. Repeatability Tests.)

(Added 1992) (Amended 2001 and 2002)

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.
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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)

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)
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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)
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