Handbook 44 – 2022 3.35. Milk Meters

3-87

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

Table of Contents

Page

Section 3.35. Milk Meters ................................................................................................... 3-89

A. Application ...................................................................................................................................................3-89

A.1. General................................................................................................................................................3-89

A.2. Exceptions...........................................................................................................................................3-89

A.3. Additional Code Requirements...........................................................................................................3-89

S. Specifications................................................................................................................................................3-89

S.1. Design of Indicating and Recording Elements and of Recorded Representations. .............................3-89

S.1.1. Primary Elements..................................................................................................................3-89

S.1.2. Graduations...........................................................................................................................3-90

S.1.3. Indicators. .............................................................................................................................3-90

S.1.4. Computing-Type Devices. ....................................................................................................3-91

S.2. Design of Measuring Elements...........................................................................................................3-91

S.2.1. Air/Vapor Elimination. .........................................................................................................3-91

S.2.2. Maintaining Flooded Condition............................................................................................3-91

S.2.3. Provision for Sealing.............................................................................................................3-91

S.2.4. Directional Flow Valves. ......................................................................................................3-92

S.3. Design of Intake Lines........................................................................................................................3-92

S.3.1. Diversion of Liquid to be Measured. ....................................................................................3-92

S.3.2. Intake Hose. ..........................................................................................................................3-92

S.4. Marking Requirements........................................................................................................................3-93

S.4.1. Limitation of Use. .................................................................................................................3-93

S.4.2. Discharge Rates. ...................................................................................................................3-93

S.4.3. Measuring Components. .......................................................................................................3-93

S.4.4. Flood Volume. ......................................................................................................................3-93

S.4.5. Conversion Factor.................................................................................................................3-93

N. Notes..............................................................................................................................................................3-93

N.1. Test Liquid..........................................................................................................................................3-93

N.2. Evaporation and Volume Change. ......................................................................................................3-93

N.2.1. Temperature Correction........................................................................................................3-93

N.3. Test Drafts...........................................................................................................................................3-93

N.4. Testing Procedures..............................................................................................................................3-94

N.4.1. Normal Tests.........................................................................................................................3-94

N.4.2. Special Tests. ........................................................................................................................3-94

N.4.3. System Capacity. ..................................................................................................................3-94

N.4.4. Repeatability Tests................................................................................................................3-94

T. Tolerances.....................................................................................................................................................3-94

T.1. Application..........................................................................................................................................3-94

T.1.1. To Underregistration and to Overregistration.......................................................................3-94

T.2. Tolerance Values. ...............................................................................................................................3-94

T.3. Repeatability. ......................................................................................................................................3-94

UR. User Requirements ......................................................................................................................................3-95

UR.1. Installation Requirements. ..................................................................................................................3-95

UR.1.1. Plumb and Level Condition. .................................................................................................3-95

UR.1.2. Discharge Rate......................................................................................................................3-95

UR.1.3. Unit Price. .............................................................................................................................3-95
3.35. Milk Meters Handbook 44 – 2022

3-88

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

UR.1.4. Intake Hose. ..........................................................................................................................3-95

UR.2. Use Requirements. ..............................................................................................................................3-95

UR.2.1. Return of Indicating and Recording Elements to Zero. ........................................................3-95

UR.2.2. Printed Ticket........................................................................................................................3-95

UR.2.3. Ticket in Printing Device......................................................................................................3-95

UR.2.4. Credit for Flood Volume.......................................................................................................3-95
Handbook 44 – 2022 3.35. Milk Meters

3-89

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

Section 3.35. Milk Meters

A. Application

A.1. General. – This code applies to devices used for the measurement of milk; generally applicable to, but not 

limited to, meters used in dairies, milk processing plants, and cheese factories, to measure incoming bulk milk.

A.2. Exceptions. – This code does not apply to mass flow meters. (Also see Section 3.37. Code for Mass Flow 

Meters.)

(Added 1994)

A.3. Additional Code Requirements. – In addition to the requirements of this code, Milk Meters shall meet the 

requirements of Section 1.10. General Code.

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.

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 shall be in terms of decimal subdivisions. Fractional parts 

of the gallon shall be in terms of either decimal or binary subdivisions.

(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. The weight value division 

shall be a decimal multiple or submultiple of 1, 2, or 5. Fractional parts of the kilogram or pound 

shall be in decimal subdivisions. (Also see S.4.5. Conversion Factor.)

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

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

(a) 0.5 L or 0.5 kg (1 pt or 1 lb) when measuring quantities less than or equal to 4000 L or 4000 kg 

(1000 gal or 8600 lb); or

(b) 5 L or 5 kg (1 gal or 10 lb) when measuring quantities in excess of 4000 L or 4000 kg (1000 gal or 

8600 lb).

(Amended 1989)

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.
3.35. Milk Meters Handbook 44 – 2022

3-90

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

S.1.1.5. Return to Zero. – Primary indicating elements and primary recording elements, if the device is 

equipped to record, shall be readily returnable to a definite zero indication. Means shall be provided to 

prevent the return of the primary indicating elements and the primary recording elements, if the device is so 

equipped, beyond their correct zero position.

S.1.1.6. Indication of Measurement. – A meter shall be constructed to show automatically its initial zero 

condition and the volume measured up to the nominal capacity of the device.

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) in width.

S.1.2.3. Clear Interval between Graduations. – The clear interval shall be not less than 1.0 mm 

(0.04 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.

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 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 be not less than 5 mm (0.20 in).
Handbook 44 – 2022 3.35. Milk Meters

3-91

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

S.1.4. Computing-Type Devices.

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

on the outside of the device, and in close proximity to the display of the total computed price, the price per 

unit at which the device is set to compute.

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

computed price, the ticket also shall 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 1 cent.

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 indicating or representation to within 1 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 2017)

S.2.2. Maintaining Flooded Condition. – The vent on the vapor eliminator shall be positioned or installed in 

such a manner that the vapor eliminator cannot easily be emptied between uses.

S.2.3. 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 an 

adjustment or interchange can be made of any:

(a) measuring element or indicating element;

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

and

(c) 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.2.3. Categories of Device and Methods of Sealing.*

[*Nonretroactive as of January 1, 1995]

(Amended 2006 and 2019)
3.35. Milk Meters Handbook 44 – 2022

3-92

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

Table S.2.3. 

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 onsite 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.2.4. Directional Flow Valves. – Valves intended to prevent reversal of flow shall be automatic in operation.

S.3. Design of Intake Lines.

S.3.1. 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. A manually controlled outlet 

that may be opened for purging or draining the measuring system shall be permitted. Effective means shall be 

provided to prevent passage of liquid through any such outlet during normal operation of the measuring system.

(Amended 1994)

S.3.2. Intake Hose. – The intake hose shall be:

(a) of the dry-hose type;

(b) adequately reinforced;
Handbook 44 – 2022 3.35. Milk Meters

3-93

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

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

transfer from a supply tank; and

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

(Amended 1991)

S.4. Marking Requirements.

S.4.1. 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.4.2. Discharge Rates. – A meter shall be marked to show its designed maximum and minimum discharge 

rates. The marked minimum discharge rate shall not exceed 20 % of the marked 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.4.3. Measuring Components. – 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.4.4. Flood Volume. – When applicable, the volume of product (to the nearest minimum division of the meter) 

necessary to flood the system when dry shall be clearly, conspicuously, and permanently marked on the air 

eliminator.

S.4.5. 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.

N. Notes

N.1. Test Liquid.

(a) A meter 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 1989)

(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)

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.2.1. Temperature Correction. – Corrections shall be made for any changes in volume resulting from the 

differences in liquid temperatures between time of passage through the meter and time of volumetric

determination in the test measure. When adjustments are necessary, appropriate tables should be used.

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

maximum discharge rate, and shall in no case be less than 400 L or 400 kg (100 gal or 1 000 lb).

(Amended 1989)
3.35. Milk Meters Handbook 44 – 2022

3-94

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

N.4. Testing Procedures.

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

anticipated under the conditions of the installation. The “normal” test shall include a determination of the 

effectiveness of the air elimination system.

N.4.2. Special Tests. – “Special” tests shall be made to develop the operating characteristics of a device 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 shall be considered a special test.

N.4.3. System Capacity. – The test of a milk-metering system shall include the verification of the volume of 

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

N.4.4. 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 discharge rates shall be within the minimum and maximum discharge rates as marked by 

the manufacturer.

(Amended 2019)

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. – Maintenance and acceptance tolerances shall be as shown in Table 1. Tolerances for Milk 

Meters.

(Amended 1989)

Table 1.

Tolerances for Milk Meters

Indication Maintenance Acceptance

gallons gallons 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.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.4.4. Repeatability Tests.

(Added 2002) (Amended 2019)
Handbook 44 – 2022 3.35. Milk Meters

3-95

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

UR. User Requirements

UR.1. Installation Requirements.

UR.1.1. Plumb and Level Condition. – A device installed in a fixed location shall be installed plumb and 

level, and the installation shall be sufficiently strong and rigid to maintain this condition.

UR.1.2. 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.1.3. 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.1.4. Intake Hose. – The intake hose shall be so installed as to permit complete drainage and that all 

available product is measured following each transfer.

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 before each 

transfer.

UR.2.2. Printed Ticket. – Any printed ticket issued by a device of the computing type on which there is printed 

the total computed price, the total quantity, or the price per unit of quantity, shall also show the other two values 

(either printed or in clear script).

(Amended 1989)

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 transfer is begun. If the meter is mounted on a vehicle, 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 ticket of each transfer affected.
3.35. Milk Meters Handbook 44 – 2022

3-96

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

THIS PAGE INTENTIONALLY LEFT BLANK