Handbook 44 – 2009 3.35. Milk Meters 

Section 3.35. Milk Meters 

A. Application 

A.1. 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. See also Section 1.10. General Code requirements. 

A.3. This code does not apply to mass flow meters (see Section 3.37. Code for Mass Flow Meters). 

(Added 1994) 

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. (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 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. 

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. 

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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 then 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). 

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. 

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

effective means automatic in operation 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 suitably rigid material. 

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. – 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 may be made of: 

(a) any measuring element 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.2.3. Categories of Device and Methods of Sealing]* 

[*Nonretroactive as of January 1, 1995] 

(Amended 2006) 

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3.35. Milk Meters Handbook 44 – 2009 

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 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 ten 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.2.4. 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, 

(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) 

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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: 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 1 minute at its maximum 

discharge rate, and shall in no case be less than 400 L or 400 kg (100 gal or 1000 lb). 

(Amended 1989) 

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. 

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N.4.1.1. 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 2002) 

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. 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. 

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. 

(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 (see also N.4.1.1. Repeatability Tests).

(Added 2002) 

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. 

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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. 

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