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Standard capacity measures for te

measuring systems for liquids othe

Mesures de capacité étalons pour l'essai des ensede mesurage de liquides autres que l'eau

(Editio

INTERNATIONAL

RECOMMENDATION

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Updated references

OIML TC 8 updated the following references in this Publication in 2010:

Chapter Reference Document

p.4,Terminology

VIM:1993International vocabulary of basic and generalterms in metrology

O

p.4,Terminology

VML:1978 Vocabulary of legal metrology O

p.5, Scope OIML R 117:1995 Measuring systems for liquids other than water R

p.6, 2.1 OIML R 43Standard graduated glass flasks for verification

officersO

OIML R 76-1:1992 O p.12, 3.5.2

OIML R 76-2:1993 Non automatic weighing instruments

O

p.15, 4.7OIML R 63:1994

/ ISO 91-1, 1994 edition

Petroleum measurement tables, (with reference

to ISO International Standard 91-1:1982& 91-2:1991)

N

p.15, 4.7 ISO 8222:1987

Petroleum measurement systems--Calibration--Temperature corrections for use with

volumetric ref. Measuring systemsIS

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CONTENTS

Foreword .............................................................................................................

Terminology ........................................................................................................

1 Scope ........................................................................................................

2 Standard capacity measures ...................................................................2.1 Nominal capacities and construction materials ...................................2.2 Accuracy ..................................................................................................

2.3 Construction ............................................................................................2.4 Markings ..................................................................................................

3 Calibration methods for standard capacity measures ..........................3.1 Reference temperature ............................................................................

3.2 Liquids used for calibration ....................................................................3.3 Measures constructed “to contain” and “to deliver” .............................3.4 Drainage time ..........................................................................................

3.5 Gravimetric method ................................................................................3.6 Volumetric method ..................................................................................

4 General requirements for testing measuring systems usingstandard capacity measures ...................................................................

4.1 Test liquids ...............................................................................................4.2 Preliminary runs .....................................................................................

4.3 Temperature and pressure measurement ...............................................4.4 Test flowrates ..........................................................................................4.5 Test volumes ............................................................................................

4.6 Number of test runs ................................................................................4.7 Calculation of meter error .......................................................................

5 Test procedures for measuring systems .................................................

6 Test procedure for a meter on its own or fitted with ancillary devices

7 Test procedure for a fuel dispenser ........................................................

8 Test procedure for a measuring system on road tanker ........................

9 Test procedure for a measuring system for the unloading of road and

tankers, ships’ tanks and tank containers ...............................................

10 Test procedure for a measuring system for the loading of road and ra

tankers, ships’ tanks and tank containers ...............................................

11 Test procedure for a measuring system fitted into a pipeline ..............

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FOREWORD

The International Organization of Legal Metrology (OIML) is a worldwide, intergovewhose primary aim is to harmonize the regulations and metrological controls applied logical services, or related organizations, of its Member States.

The two main categories of OIML publications are:

1) International Recommendations (OIML R), which are model regulations that estcharacteristics required of certain measuring instruments and which specify metho

checking their conformity; the OIML Member States shall implement these Recgreatest possible extent;

2) International Documents (OIML D), which are informative in nature and intendeof the metrological services.

OIML Draft Recommendations and Documents are developed by technical commitwhich are formed by the Member States. Certain international and regional institutionconsultation basis.

Cooperative agreements are established between OIML and certain institutions, such

the objective of avoiding contradictory requirements; consequently, manufacturers ainstruments, test laboratories, etc. may apply simultaneously OIML publications antutions.

International Recommendations and International Documents are published in Frenand are subject to periodic revision.

OIML publications may be obtained from the Organization's headquarters:

Bureau International de Métrologie Légale11, rue Turgot - 75009 Paris - France

Telephone: 33 (0)1 48 78 12 82 and 42 85 27 11Fax: 33 (0)1 42 82 17 27

** *

This publication - reference OIML R 120, edition 1996 (E) - was developed withicommittee TC 8 Measurement of quantities of fluids. It was approved for final publicatioCommittee of Legal Metrology in 1994 and will be submitted to the InternationalMetrology in 1996 for formal sanction.

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TERMINOLOGY

The general terms used in this Recommendation are in accortional Vocabulary of Basic and General Terms in Metrology (VIM Vocabulary of Legal Metrology (VML - 1978 edition).

Other technical terms used in this text are in accordance wit

commendation OIML R 117 Measuring systems for liquids oedition).

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STANDARD CAPACITY MEASURES

FOR TESTING MEASURING SYSTEMS FOR LIQ

OTHER THAN WATER

1 Scope

This Recommendation specifies the characteristics of standardand describes the methods by which measuring systems for liquid(hereinafter called “measuring systems”) are tested in order to veriwith the relevant metrological requirements in the InternationalOIML R 117 Measuring systems for liquids other than water.

In points 2 and 3 the metrological characteristics and the calib

standard capacity measures are defined.

In points 4 to 12, the methods are given for testing the followingsystems:

1) liquid fuel dispensers (except for LPG),

2) measuring systems on road tankers,

3) measuring systems for the unloading of road and rail tankers, shcontainers,

4) measuring systems for the loading of road and rail tankers, shcontainers,

5) measuring systems fitted into pipelines,

6) measuring systems for milk.

Other types of measuring systems or measuring systems for othmay generally be tested according to one of the above methods.

This Recommendation does not apply to measuring systems (LPG and LNG), cryogenic liquids or liquids having a viscosity abomeasuring systems will be covered by separate Recommendations.

2 Standard capacity measures

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Table 1

Standard flasks shall be made of glass as specified in themendation OIML R 43 Standard graduated glass flasks for verific

Standard test measures and proving tanks shall be made of swith a suitable interior coating, or other materials as specified i

2.2 Accuracy

2.2.1 General

The calibration of a standard capacity measure shall be capanded uncertainty on calibration be within one-fifth of the error on pattern approval tests and one-third of the maximum prification tests. The estimation of uncertainty shall be made ac

the expression of uncertainty in measurement, with k = 2. includes uncertainty on measurement standards, uncertainty onand uncertainty on the capacity measure being calibrated. Whemeasure is calibrated, the expanded uncertainty of the calibratthe calibration certificate.

2.2.2 Maximum permissible errors

2.2.2.1 For standard flasks, the maximum permissible errors sh

fied in clause 7 of OIML R 43.

2.2.2.2 For standard test measures and proving tanks, the maximshall be ± 1/2 000 of the nominal capacity.

2.2.2.3 The requirement in 2.2.2.2 also applies to the scale intsides of the scale mark corresponding to the nominal capacity o

Description of standard capacity Nominmeasures

Standard flasks 0.1 –1 – 2

Standard test measures 5 –

Proving tanks 20

Standard flasks for special uses 0.2

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2.3.2 Standard test measures

The diameter of the neck of the standard test measure shall be laproblems with regard to the trapping of liquid or air or vapor or tomeasure, and small enough so that the sensitivity in detecting chathe measure is sufficient for achieving the measurement accuracy rassumed that the requirement will be met if a difference of at leastlevel in the neck is equivalent to the absolute value of the maximumof the standard capacity measure.

The neck part shall be of the weir-type, or have glass plates, o

tube, or have a separate and fixed gauge glass(es). The scale markthe nominal capacity and to at least 1 % of the nominal capacity, inshall be marked on the glass plates, the glass tube neck or the gaugthe neck part shall be fitted with a fixed, rustproof metal plate or able of being sealed, and on which the scale marks corresponding tcity, and to the volumes below and above the nominal capacity, aremarks on the metal plate fixed to the neck part, shall be inscribed oplate, adjacent to the window.

The diameter of the gauge glass shall be large enough to ensumeniscus effects do not introduce additional uncertainties such permissible errors given in 2.2.2.2 are exceeded (*).

If adjustment plungers are used, they shall not move easily afte volume and shall be capable of being sealed.

It shall be ensured that the liquids are easily delivered to and measures, and that no pockets, dents or crevices capable of trappior vapor are present.

Examples of different designs of a standard test measure are show

2.3.3 Proving tanks

2.3.3.1 Proving tanks shall be provided with drain valves at the bottobe designed with a top neck and may be designed with a bottomments given in 2.3.2 on the diameter of the neck of standard te

equally to the diameter of the top and bottom necks of proving tankThe top neck should be provided with glass plates or a sepa

glass(es), on which the scale marks corresponding to the nominal cations of at least 1 % of the nominal capacity, in plus and in minus,wise, the top neck part shall be fitted with a fixed and rustproosliding plate capable of being sealed and on which the scale marks c

i l it d t th l b l d b th i l

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uncertainties such that the maximum permissible errors given (see note to 2.3.2).

It shall be ensured that the liquids are easily delivered to andand that no pockets, dents or crevices capable of trapping the present.

Examples of different designs of a proving tank are shown in

2.3.3.2 The proving tank shall be provided with means for measuthe liquid it contains.

When thermometer wells are used for determining the tempein the proving tank, the minimum recommended number ofgiven in Table 2.

Table 2

The thermometer well shall be deep enough to enable the thermometer and shall consist of a metal socket with good heone end closed; it shall be inclined so that liquid can be addedThe thermometer wells shall be installed with such an immetemperature outside the proving tank will not affect the thermo

When the installation of two or three thermometer wells i

shall be installed in accordance with the following location conda) in the upper and lower half of the main body, or in the upp

near the center of the main body of the proving tank, and

b) at two or three points, equally spaced around the circumtank.

2.3.3.3 Where proving tanks are mounted on a truck or trailer, mto secure and maintain them in a level position, during testing a

2.3.3.4 For testing certain types of measuring systems (for examption of milk), it may be easier to use proving tanks of the brim m

2.4 Markings

Standard capacity measures shall be marked on a permanen

Nominal capacity up to more than 500of a proving tank 500 L up to 2 000 L

Minimum number

1 2of thermometer wells

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3 Calibration methods for standard capacity measures

3.1 Reference temperature

The value of the reference temperature of the standard capacityin national regulations shall be stated in the calibration report anditself.

3.2 Liquids used for calibration

3.2.1 Standard flasks and standard test measures

The liquid used for the calibration of standard flasks and stanshall be water as specified in OIML R 43.

3.2.2 Proving tanks

The liquid used for the calibration of proving tanks shall be w

clean and free of contaminants or corrosive chemicals and which sor gas bubbles.

3.3 Measures constructed “to contain” and “to deliver”

The method of calibration should correspond to the manner in wto be used; e.g. a measure constructed “to deliver” shall be calibrathe volume of the water it discharges, with a specific drainage tim

constructed “to contain” shall be calibrated by determining the vwhich is required to fill the dry or pre-wetted measure, as applicable

3.3.1 Standard flasks

Determination of the capacity of a standard flask shall follow thfied in OIML R 43.

3.3.2 Standard test measures

The capacity of a standard test measure may be determined usingtain” or “to deliver” method. Where the viscosity of the liquid usethe measuring system does not exceed 5 mPa·s, the capacity of the ure should be determined using the “to deliver” or pre-wetted “to co

3 3 3 P i k

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3.4.1 Standard flasks and standard test measures

A standard flask or standard test measure, after being filled marks, shall be emptied by pouring so that the liquid flows outhe rim. After the flow breaks into drops, the standard flask or drained by holding it vertically for 30 seconds, then quickly retposition.

3.4.2 Proving tanks

A drainage time of 30 seconds should be allowed after the mathe flow breaks into drops.

For proving tanks to which the delivery time applies, it is rethis delivery time so that the fall rate of the liquid level in thedoes not exceed 1 cm/s. The proving tank may also be fitted wifying that it is emptied completely.

3.5 Gravimetric method

The gravimetric method is recommended for the calibratio

measures.

3.5.1 Standard flasks

Standard flasks shall be calibrated using the gravimetric metR 43.

3.5.2 Standard test measures and proving tanks

Standard test measures and proving tanks should be calibramethod which, in principle, shall follow the method described weighing instrument of an adequate accuracy class, as specifi automatic weighing instruments, is recommended for calibratio

3.6 Volumetric method

Standard capacity measures may be calibrated using the voliquid transfer and other standard capacity measures which hav

accuracy level significantly higher than that of the measure to bmetric method may be used where the capacity of a standard large that the use of weighing instruments is impracticable or ible errors of the available weighing instruments are excessthose intended for the standard capacity measure.

Two volumetric methods may be used: the withdrawing m

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rated using the gravimetric method. An automatic pipette is a suitpurpose. This method shall be carried out in situ and within a periotemperature in the standard capacity measure being calibrated withan 2 °C during the filling.

4 General requirements for testing measuring systems using st

capacity measures

If the test method is such that the standard capacity measures aditions that differ from their calibration method, repeatability mustany systematical difference must be evaluated and used for correctcannot be met otherwise.

4.1 Test liquids

A measuring system shall be tested using either the liquid markeof the system or a liquid whose viscosity and other flow characteriranges of those of the stated liquid.

Any regulation concerning the security for handling the system sh

A measuring system for milk shall be tested with either milk or pever, during the test in situ, only milk should be used as test liquid.

4.2 Preliminary runs

A sufficient number of preliminary runs shall be carried out beorder to eliminate any air that may be contained in the measutesting equipment, and to ensure that the temperatures of the liquthe measuring system and the standard capacity measures are stabl

A leakage test of the measuring system shall be carried out before

4.3 Temperature and pressure measurement

4.3.1 Temperature measuring devices shall be used to determine theature correction for the test liquid, the measuring system and themeasures being used These devices shall be mounted at represen

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4.4 Test flowrates

The number of flowrates at which the measuring system shfied in OIML R 117, or in other OIML Recommendations for tmeasuring systems.

The following flowrates are recommended as a minimum.

4.4.1 For the verification of a meter or for the first stage in awhere the first stage concerns the meter itself or any ancillaryassociated with it and possibly included in a sub-system if these

the tests shall be carried out at the following flowrates:• the minimum flowrate Qmin, stated on the meter,

• the maximum flowrate Qmax, stated on the meter,

• a flowrate between Qmin and Qmax.

4.4.2 For the second stage in a two-stage verification or for the cstage verification, and for the subsequent verification of a meashall be carried out at the following flowrates:

• the minimum flowrate Qmin, stated on the measuring system,• the maximum attainable flowrate, but not exceeding Qmax,

• a flowrate at which the measuring system is normally operate

4.5 Test volumes

4.5.1 For the verification described in 4.4.1, the smallest volumeflowrate shall be as follows:

• at Qmin, the minimum measured quantity stated on the meter• at other flowrates, at least three times the minimum measure

4.5.2 For the verification described in 4.4.2, the smallest volumeflowrate shall be as follows:

• at Qmin, the minimum measured quantity stated on the measu

• at other flowrates, at least three times the minimum measure

4.5.3 It is recommended that, at all flowrates, the test time sho1 min.

4.5.4 At least one test shall be carried out using a volume equal ured quantity.

b f

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4.7 Calculation of meter error

The value of the meter error is determined using the following eqE = E’ + E

α + E

β

E’ = [(V m – V s) / V s] × 100

Eα

= α (ts – tm) × 100

Eβ

= β (tr– ts

) × 100

where

E is the meter error, in %

E’ is the uncorrected error, in %

Eα

is the temperature correction for the test liquid, in %

Eβ

is the temperature correction for the standard capacity measur

V m is the volume indicated by the meter, in L

V s is the volume measured in the standard capacity measure, in L

ts is the average liquid temperature in the standard capacity meas

tmis the average liquid temperature in the meter, in °C

tr is the reference temperature of the standard capacity measure,

α is the cubic expansion coefficient of the test liquid due to temp

β is the cubic expansion coefficient of the standard capacity meaature, in °C–1

Notes: α : Refer to OIML R 63 or ISO 91-1 for petroleum productfor water

β : 33 × 10–6 °C–1 for mild steel, 51 x 10–6 °C–1 for stainless st

An example of a test report is given in Annex A.

5 Test procedures for the verification of measuring systems

The test procedures described in clauses 6 to 12 may be used fofollowing typical measuring systems:

clause 6: • meter on its own or fitted with ancillary devices

clause 7: • fuel dispenser

clause 8: • measuring system on a road tanker

clause 9: • measuring system for the unloading of road and rail tand tank containers

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6 Test procedure for a meter on its own or fitted with ancillary d

–

1 6

–

(*) Symbols used: O = open; X = closed (pump or valve). These symbols are also

(**) The standard test measure and the proving tank shall be emptied and drain

(***) V m: Volume indicated by the meter or system; V s: Volume measured in the

(****) Flowrate shall be controlled V4.

(*****) Average temperature tm is determined by the results observed during te volume.

(******) E’, E, Eα , Eβ : refer to 4.7. This note applies also to the following tables.

N° Procedure P V1 V2

1 Before the test X X X

2 Meter installation in the test line

3 Preliminary run O O O

4 Proving tank draining X X X

5 Start reading Observe and rec

6 Test run (1) O O O(2) X X X

(3) Observe and rec

(4) Observe and rec


8 Calculate uncorrected error E’ (%)

9 Calculate meter error E (%) (E = E’ + Eα + Eβ )

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–

1 8

–

7 Test procedure for a fuel dispenser (Figure 4)

(*) A proving tank, or a large or small standard test measure, is used according

(**) Every testing shall be carried out after resetting the volume indicator to zer

(***) Flowrate shall be controlled by the nozzle.

(****) The nozzle shall be taken out of the standard capacity measure after it ha

N° Procedure N Sw Pm

1 Before the test operation X X X

2 Preliminary run (1) Insert nozzle in

(2) O O O

(3) Insert closed no

(4) O O O

3 Standard capacity measure draining X O O4 Test run (1) Reset indicator

(2) O O O

(3) Observe and rec

5 Standard capacity measure draining X O O

6 Calculate meter error for the test run E’ (%)

7 When the measuring system is fitted with a price indicator a

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–

2 0

–

8 Test procedure for a measuring system on road tanker

8.1 In the case of a road tanker with delivery pump (Figure 5)

(*) A portable proving tank may be used. This note applies also to the following

(**) Flowrate shall be controlled by V1.

N° Procedure P1 V1 V2


2 Connect delivery hose to inlet of proving tank (*) and open

3 Preliminary run O O O



6 Test run (1) O O O

(2) X X X

(3) Observe and rec

(4) Observe and rec


8 Calculate uncorrected error E’ (%)

9 Calculate meter error E = E’ + Eα

+ Eβ

(%)

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–

2 2

–

8.2 In the case of a road tanker delivered by gravity (Figure 6)

N° Procedure V1 V2 V3


2 Connect delivery hose to inlet of proving tank and open com

3 Preliminary run O O X

4 Proving tank draining X X O


6 Test run (1) O O X(2) X X X

(3) Observe and rec

(4) Observe and rec

7 Proving tank draining X X O

8 Calculate uncorrected error for the test run E’ (%)


+ Eβ

(%)

Note: In the case of a road tanker delivered by gravity, it is esstanker and the proving tank for obtaining the test flowrate

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–

2 4

–

9 Test procedure for a measuring system for the unloading of roa

9.1 Test run being carried out during unloading operation (Figur

Notes: (1) Flowrate shall be controlled by V4.

(2) It is essential to maintain a constant level on the siduring a test run. This note applies to the following cl

(3) In bypass line, double valve or block-and-bleed valveclauses.

N° Procedure P1 V1 V2 V3 V4

1 Preliminary run O O O O O

2 Proving tank draining X X X X X

3 Test procedure Refer to 8.1, Nos. 5 to 9

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–

2 6

–

9.2 Test run being carried out without unloading operation (Figu

N° Procedure P V1 V2 V3 V

1 Proving tank filling X X X X X

2 Connect ready filled proving tank to unloading pump of roa


4 Proving tank draining O O O O O


6 Start reading Observe and record V m1an

7 Test run (1) O O O O O

(2) Observe and record t1

(3) O O O O O

(4) X X X X X

(5) Observe and record V m2an


9 Calculate uncorrected error for the test run E’ (%)


+ Eβ

(%)

Note: This method should be applied e.g. when the test is imposs

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–

2 8

–

10 Test procedure for a measuring system for the loading of road

Note: Flowrate shall be controlled by V4

.




3 Test procedure Refer to 8.1, Nos. 5 to 9

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–

3 0

–

11 Test procedure for a measuring system fitted into a pipeline (F

Notes: (1) Flowrate shall be controlled by V4.

(2) Drained liquid from the proving tank may be returned




3 Test procedures Refer to 8.1, Nos. 5 to 9

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–

3 2

–

12 Test procedure for a measuring system for milk

12.1 Road tanker with delivery pump (Figure 11)

Refer to 8.1, Nos. 3 to 9.

12.2 Road tanker with suction pump (Figure 12)Refer to 9.2, Nos. 3 to 10. In this case, the valve V

7is always

12.3 Reception at dairy (Figure 13)Apply the procedure referred to in 12.1.

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