EN ISO 7278-2:2022
(Main)Petroleum measurement systems - Part 2: Pipe prover design, calibration and operation (ISO 7278-2:2022)
Petroleum measurement systems - Part 2: Pipe prover design, calibration and operation (ISO 7278-2:2022)
This document provides descriptions of the different types of pipe provers, otherwise known as displacement provers, currently in use. These include sphere (ball) provers and piston provers operating in unidirectional and bidirectional forms. It applies to provers operated in conventional, reduced volume, and small volume modes.
This document gives guidelines for:
— the design of pipe provers of each type;
— the calibration methods;
— the installation and use of pipe provers of each type;
— the interaction between pipe provers and different types of flowmeters;
— the calculations used to derive the volumes of liquid measured (see Annex A);
— the expected acceptance criteria for fiscal and custody transfer applications, given as guidance for both the calibration of pipe provers and when proving flowmeters (see Annex C).
This document is applicable to the use of pipe provers for crude oils and light hydrocarbon products which are liquid at ambient conditions. The principles apply across applications for a wider range of liquids, including water. The principles also apply for low vapour pressure, chilled and cryogenic products, however use with these products can require additional guidance.
Mineralölmesssysteme - Teil 2: Auslegung, Kalibrierung und Betrieb von Rohrprüfgeräten (ISO 7278-2:2022)
Dieses Dokument enthält Beschreibungen der verschiedenen zur Zeit verwendeten Arten von Rohrprüfern; diese werden auch als Verdrängungsprüfer bezeichnet. Dazu gehören Kugelprüfer und Kolbenprüfer, die entweder unidirektional oder bidirektional betrieben werden. Es gilt für Prüfer, die in herkömmlicher Weise und in Betriebsarten für reduzierte Volumina sowie kleine Volumina betrieben werden.
Dieses Dokument enthält Leitlinien für:
— die Auslegung von Rohrprüfern jedes der einzelnen Typen;
— die Kalibrierverfahren;
— die Installation und die Verwendung von Rohrprüfern jedes der einzelnen Typen;
— die Wechselwirkung zwischen Rohrprüfern und verschiedenen Arten von Durchflussmessgeräten;
— die Berechnungen zur Ableitung der gemessenen Flüssigkeitsvolumina (siehe Anhang A);
— die für fiskalische und eichpflichtige Verkehrsanwendungen erwarteten Annahmekriterien, angegeben als Leitlinien sowohl für die Kalibrierung von Rohrprüfern als auch für die Prüfung von Durchflussmessgeräten (siehe Anhang C).
Dieses Dokument ist anzuwenden für die Verwendung von Rohrprüfern für Rohöle und leichte Kohlenwasserstoffprodukte, die bei Umgebungsbedingungen flüssig sind. Die hierin angegebenen Grundsätze gelten auch für Anwendungen mit weiteren Flüssigkeiten, einschließlich Wasser. Die Grundsätze gelten auch für Produkte mit niedrigem Dampfdruck sowie gekühlte und tiefkalte Produkte, jedoch kann die Verwendung mit diesen Produkten zusätzliche Leitlinien erfordern.
WARNUNG — Die Anwendung dieses Dokuments kann die Anwendung gefährlicher Stoffe, Arbeitsgänge und Geräte mit sich bringen. Dieses Dokument beansprucht nicht, sämtliche mit seiner Anwendung verbundenen Sicherheitsprobleme zu behandeln. Es liegt in der Verantwortung des Anwenders dieses Dokuments, geeignete Verhaltensregeln zur Sicherheit und Gesundheit festzulegen.
Systèmes de mesurage des produits pétroliers - Partie 2: Conception, étalonnage et fonctionnement des tubes étalons (ISO 7278-2:2022)
Le présent document décrit les différents types de tubes étalons, également appelés “étalons à déplacement”, actuellement utilisés. Cela comprend les tubes étalons à sphère et à piston, fonctionnant de manière unidirectionnelle et bidirectionnelle. Le présent document s'applique aux tubes étalons fonctionnant en mode conventionnel, à volume réduit et à petit volume.
Le présent document fournit des lignes directrices concernant:
— la conception des tubes étalons de chaque type;
— les méthodes d'étalonnage;
— l'installation et l'utilisation des tubes étalons de chaque type;
— l'interaction entre les tubes étalons et différents types de débitmètres;
— les calculs utilisés pour obtenir les volumes de liquide mesurés (voir l'Annexe A);
— les critères d'acceptation attendus pour les applications fiscales et de transactions commerciales, donnés à titre de recommandation, à la fois pour l'étalonnage des tubes étalons et la vérification des débitmètres (voir l'Annexe C).
Le présent document s'applique à l'utilisation de tubes étalons pour le pétrole brut et les produits d'hydrocarbure légers qui sont à l'état liquide dans les conditions ambiantes. Les principes cités s'appliquent à différentes applications ayant recours à un éventail plus large de liquides, y compris l'eau. Ces principes s'appliquent également aux produits à faible pression de vapeur, ainsi qu'aux produits refroidis et cryogéniques. Toutefois, l'utilisation de ces produits peut nécessiter des recommandations supplémentaires.
Merilni sistemi za nafto - 2. del: Načrtovanje, kalibracija in delovanje merilnika cevi (ISO 7278-2:2022)
Ta dokument podaja opise različnih merilnikov cevi (znanih tudi kot merilniki premika), ki so trenutno v uporabi. To vključuje kroglične in batne merilnike z enosmernim oziroma dvosmernim delovanjem. Uporablja se za merilnike, ki delujejo v običajnem načinu, načinu z zmanjšano in majhno prostornino.
Ta dokument podaja smernice za:
– načrtovanje merilnikov cevi posamezne vrste;
– kalibracijske metode;
– namestitev in uporabo merilnikov cevi posamezne vrste;
– medsebojno delovanje merilnikov cevi in različnih vrst merilnikov pretoka;
– izračune, ki se uporabljajo za izpeljavo izmerjene prostornine tekočine (glej dodatek A);
– pričakovane kriterije sprejemljivosti za fiskalni prenos in prenos skrbništva, podane kot smernice za kalibracijo merilnikov cevi in preskušanje merilnikov pretoka (glej dodatek C).
Ta dokument je namenjen za uporabo merilnikov cevi za surovo nafto in izdelke iz lahkega ogljikovodika, ki so pri običajnih okoljskih pogojih v tekočem stanju. Načela se uporabljajo za različne vrste tekočin, vključno z vodo. Prav tako se uporabljajo za izdelke z nizkim parnim tlakom ter ohlajene in kriogene izdelke, vendar so lahko pri takšni uporabi potrebne dodatne smernice.
General Information
Relations
Standards Content (Sample)
SLOVENSKI STANDARD
01-februar-2023
Nadomešča:
SIST EN ISO 7278-2:1998
Merilni sistemi za nafto - 2. del: Načrtovanje, kalibracija in delovanje merilnika cevi
(ISO 7278-2:2022)
Petroleum measurement systems - Part 2: Pipe prover design, calibration and operation
(ISO 7278-2:2022)
Flüssige Kohlenwasserstoffe - Dynamische Messung - Prüfsysteme für volumetrische
Messgeräte - Teil 2: Rohrprüfer (ISO 7278-2:2022)
Systèmes de mesurage des produits pétroliers - Partie 2: Conception, étalonnage et
fonctionnement des tubes étalons (ISO 7278-2:2022)
Ta slovenski standard je istoveten z: EN ISO 7278-2:2022
ICS:
75.180.30 Oprema za merjenje Volumetric equipment and
prostornine in merjenje measurements
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
EN ISO 7278-2
EUROPEAN STANDARD
NORME EUROPÉENNE
November 2022
EUROPÄISCHE NORM
ICS 75.180.30 Supersedes EN ISO 7278-2:1995
English Version
Petroleum measurement systems - Part 2: Pipe prover
design, calibration and operation (ISO 7278-2:2022)
Systèmes de mesurage des produits pétroliers - Partie Flüssige Kohlenwasserstoffe - Dynamische Messung -
2: Conception, étalonnage et fonctionnement des tubes Prüfsysteme für volumetrische Messgeräte - Teil 2:
étalons (ISO 7278-2:2022) Rohrprüfer (ISO 7278-2:2022)
This European Standard was approved by CEN on 28 October 2022.
CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this
European Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references
concerning such national standards may be obtained on application to the CEN-CENELEC Management Centre or to any CEN
member.
This European Standard exists in three official versions (English, French, German). A version in any other language made by
translation under the responsibility of a CEN member into its own language and notified to the CEN-CENELEC Management
Centre has the same status as the official versions.
CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia,
Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway,
Poland, Portugal, Republic of North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Türkiye and
United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION
EUROPÄISCHES KOMITEE FÜR NORMUNG
CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2022 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 7278-2:2022 E
worldwide for CEN national Members.
Contents Page
European foreword . 3
European foreword
This document (EN ISO 7278-2:2022) has been prepared by Technical Committee ISO/TC 28
"Petroleum and related products, fuels and lubricants from natural or synthetic sources" in
collaboration with Technical Committee CEN/TC 19 “Gaseous and liquid fuels, lubricants and related
products of petroleum, synthetic and biological origin” the secretariat of which is held by NEN.
This European Standard shall be given the status of a national standard, either by publication of an
identical text or by endorsement, at the latest by May 2023, and conflicting national standards shall be
withdrawn at the latest by May 2023.
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CEN shall not be held responsible for identifying any or all such patent rights.
This document supersedes EN ISO 7278-2:1995.
Any feedback and questions on this document should be directed to the users’ national standards
body/national committee. A complete listing of these bodies can be found on the CEN website.
According to the CEN-CENELEC Internal Regulations, the national standards organizations of the
following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria,
Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland,
Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Republic of
North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Türkiye and the
United Kingdom.
Endorsement notice
The text of ISO 7278-2:2022 has been approved by CEN as EN ISO 7278-2:2022 without any
modification.
INTERNATIONAL ISO
STANDARD 7278-2
Second edition
2022-11
Petroleum measurement systems —
Part 2:
Pipe prover design, calibration and
operation
Systèmes de mesurage des produits pétroliers —
Partie 2: Conception, étalonnage et fonctionnement des tubes étalons
Reference number
ISO 7278-2:2022(E)
ISO 7278-2:2022(E)
© ISO 2022
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on
the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address below
or ISO’s member body in the country of the requester.
ISO copyright office
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CH-1214 Vernier, Geneva
Phone: +41 22 749 01 11
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii
ISO 7278-2:2022(E)
Contents Page
Foreword .v
Introduction . vi
1 S c op e . 1
2 Nor m at i ve r ef er enc e s . 1
3 Terms, definitions, symbols and units . 1
3.1 T erms and definitions . 1
3.2 S ymbols and units . 8
4 Design classification of pipe provers .9
4 .1 C om mon f e at u r e s . 9
4 . 2 Spher e pr over s . 11
4.2.1 General . 11
4.2.2 U nidirectional sphere provers . 11
4.2.3 Bidirectional sphere provers . 13
4 . 3 P i s t on pr over s . 15
4.3.1 G eneral .15
4.3.2 U nidirectional piston provers . 16
4.3.3 B idirectional piston provers . 16
5 Operational classification of provers .16
5.1 G eneral . 16
5 . 2 C onvent ion a l pr over . 17
5.3 R educed volume prover . 18
5.4 Small volume prover . 18
6 D e sig n .20
6.1 General considerations.20
6 . 2 P r over b a r r el . 21
6.2.1 E nd chambers (launch and receive chambers) . 21
6 . 2 . 2 R u n-i n len g t h . 22
6.2.3 P rover pipe or barrel .22
6.2.4 I nternal finish . 22
6.3 P roprietary small volume piston provers . 23
6.4 Si zing of provers . 24
6.4.1 G eneral . 24
6 .4 . 2 C a l ibr at e d volu me .25
6.4.3 Length between detectors . 25
6.4.4 Diameter and Velocity .26
6 .4 . 5 P r e s s u r e lo s s .26
6 . 5 D i s placer s . 27
6.5.1 General . 27
6 . 5 . 2 Spher e s . 27
6. 5 . 3 P i s t on s .28
6.6 D isplacer Velocity . .28
6.6.1 G eneral .28
6.6.2 Minimum velocity .28
6.6.3 Maximum velocity .29
6.7 D e t e c t or s. 29
6 . 8 P r over v a l ve s .30
6.9 Additional design considerations . 31
7 A nc i l l a r y e qu ipment .32
7.1 O verview of temperature and pressure measurement . 32
7. 2 Temp er at u r e me a s u r ement . 32
7. 3 P r e s s u r e me a s u r ement .33
7.4 C a l ibr at ion c on ne c t ion s.33
iii
ISO 7278-2:2022(E)
7.5 S ystem control .34
8 P u l s e i nt er p ol at ion .34
9 I n s t a l l at ion .34
9.1 Me c h a n ic a l i n s t a l l at ion.34
9.1.1 G eneral .34
9.1.2 Fixed provers . 37
9.1. 3 Mobi le pr over s . 37
9.2 E le c t r ica l i n s t a l l at ion .38
9.3 O ther installation recommendations .38
10 T r ac e abi l it y .38
11 C a l ibr at ion .40
11.1 General .40
11.2 C alibration circuits and equipment .40
11.3 W ater draw calibration method . 42
11. 3 .1 D e s c r ip t ion . 42
11.3.2 Volumetric measure as reference . 43
11.3.3 Gravimetric as reference . 45
11.4 Master meter calibration method . 47
11.5 S equential master meter method . 50
11.6 C oncurrent master meter method . 51
11.7 C a l ibr at ion pr o c e du r e s . 51
12 Operation to prove a flowmeter .52
12.1 Setting up a prover . 52
12.2 Mobile prover prior to arrival on site . 52
12.3 Mobile prover on arrival on site . 52
12 .4 St abi l i z i n g t emp er at u r e . 53
12.5 P eriodical checks of factors affecting accuracy . 53
12.6 Meter proving operation . 53
12.7 P reliminary assessment of the results . .54
12.8 F ault finding . 55
13 S a f e t y .55
13.1 G eneral . 55
13 . 2 Per m it s .56
13.3 O pening end chambers and removing a displacer .56
13.4 S pecial precautions when proving with LPG .56
13 . 5 F i r e pr e c aut ion s . 57
13.6 M iscellaneous safety precautions . 57
13.7 S afety records . 57
Annex A (informative) Calculations .59
Annex B (informative) Selecting a prover volume for a flowmeter .70
Annex C (informative) Acceptance criteria and performance specification .72
Annex D (informative) Troubleshooting .83
Annex E (informative) Sphere or detector replacement and twin pairs of detectors .89
Annex F (informative) Pulse interpolation .91
Annex G (informative) Alternative designs .95
Annex H (informative) Calibration procedures .97
Annex I (informative) Example of prover calibration certificate . 102
Bibliography . 107
iv
ISO 7278-2:2022(E)
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out
through ISO technical committees. Each member body interested in a subject for which a technical
committee has been established has the right to be represented on that committee. International
organizations, governmental and non-governmental, in liaison with ISO, also take part in the work.
ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of
electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are
described in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the
different types of ISO documents should be noted. This document was drafted in accordance with the
editorial rules of the ISO/IEC Directives, Part 2 (see www.iso.org/directives).
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of
any patent rights identified during the development of the document will be in the Introduction and/or
on the ISO list of patent declarations received (see www.iso.org/patents).
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and
expressions related to conformity assessment, as well as information about ISO's adherence to
the World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT), see
www.iso.org/iso/foreword.html.
This document was prepared by Technical Committee ISO/TC 28, Petroleum and related products, fuels
and lubricants from natural or synthetic sources, Subcommittee SC 2, Measurement of petroleum and
related products, in collaboration with the European Committee for Standardization (CEN) Technical
Committee CEN/TC 19 Gaseous and liquid fuels, lubricants and related products of petroleum, synthetic
and biological origin, in accordance with the Agreement on technical cooperation between ISO and CEN
(Vienna Agreement).
This second edition cancels and replaces the first edition (ISO 7278-2:1988), which has been technically
revised. It also cancels and replaces the first edition of ISO 7278-4:1999, the content of which has been
incorporated.
The main changes are as follows:
— The content and scope now covers the design of pipe provers given in ISO 7278-2:1988 and the
guidance for operators given in ISO 7278-4:1999, which will be withdrawn.
— The different types of pipe prover designs and operating methods have been defined and described.
— The variety of operational methods and the means to apply them to flowmeter calibration of
different relative sizes has been described.
— The design, calibration and use of small volume (compact) prover designs has been included.
— The document has been changed from a normative document to a guidance document to reflect best
practices.
— The document takes into account changes in practice described in alternative standards produced
by the American Petroleum Institute (API) and the Energy Institute (EI).
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www.iso.org/members.html.
v
ISO 7278-2:2022(E)
Introduction
In the petroleum industry the term “proving” is used to refer to the calibration of devices used in the
measurement of quantities of crude oils and petroleum products. Proving uses specified methods to
show, or prove, that the result falls within specified acceptance criteria. Proving provides an assurance
that the resultant measurement provides an acceptable uncertainty for the duty.
A pipe prover, otherwise called a displacement prover, is a volumetric reference device providing
a calibration reference standard for flowmeters with an electronic pulsed output. The fluid remains
contained within the piping system and proving can be carried out dynamically at various flowrates
and pressures without interruption to the flow.
Pipe provers are used extensively within petroleum industry to provide in situ calibration of flowmeters
used for fiscal, custody transfer and pipeline integrity applications. They are used with both crude and
refined oils and products but may be used with many other fluids within and outside the petroleum
industry.
A pipe prover consists of a length of pipe, a section of which has had its internal volume determined
by calibration. A displacer, usually a piston or a tightly fitting sphere or ball, travels along this section
of pipe displacing an accurately determined volume of liquid. This volume can be compared with an
equivalent volume measured by the flowmeter under test.
The calibrated volume of the prover is established by the detection of the displacer passing along the
calibrated section of pipe. Detectors sense the passage of the displacer indicating the start and end
of travel through the calibrated section. The detectors trigger the counting of pulses produced by a
flowmeter using electronic counters or counters within a flow computer. As the pulses represent the
volume measured by the associated flowmeter, a calibration is achieved through the relationship with
the calibrated volume of the pipe prover.
Pipe provers are of different designs and are manufactured with a wide range of pipe diameters and
volumes. They are available for use as part of a fiscal measurement system in fixed locations and as
mobile reference devices.
Any type of flow meter giving a pulsed output may be calibrated however the volume, design and type
of the prover may impose limitations on the type and size of meter which would be compatible.
This document describes the design, construction, calibration and use of pipe provers primarily used
for the calibration, proving and verification of flowmeters used for liquid petroleum products and may
be applied to other liquid applications requiring a high standard of measurement accuracy.
vi
INTERNATIONAL STANDARD ISO 7278-2:2022(E)
Petroleum measurement systems —
Part 2:
Pipe prover design, calibration and operation
WARNING — The use of this document may involve hazardous materials, operations and
equipment. This document does not purport to address all of the safety problems associated
with its use. It is the responsibility of the user of this document to establish appropriate safety
and health practices.
1 S cope
This document provides descriptions of the different types of pipe provers, otherwise known as
displacement provers, currently in use. These include sphere (ball) provers and piston provers
operating in unidirectional and bidirectional forms. It applies to provers operated in conventional,
reduced volume, and small volume modes.
This document gives guidelines for:
— the design of pipe provers of each type;
— the calibration methods;
— the installation and use of pipe provers of each type;
— the interaction between pipe provers and different types of flowmeters;
— the calculations used to derive the volumes of liquid measured (see Annex A);
— the expected acceptance criteria for fiscal and custody transfer applications, given as guidance for
both the calibration of pipe provers and when proving flowmeters (see Annex C).
This document is applicable to the use of pipe provers for crude oils and light hydrocarbon products
which are liquid at ambient conditions. The principles apply across applications for a wider range of
liquids, including water. The principles also apply for low vapour pressure, chilled and cryogenic
products, however use with these products can require additional guidance.
2 Normat ive references
There are no normative references.
3 Terms, definitions, symbols and units
3.1 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminology databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at https:// www .electropedia .org/
ISO 7278-2:2022(E)
3.1.1
accuracy
closeness of the agreement between a measured quantity value and a true quantity value of a measurand
Note 1 to entry: The concept “measurement accuracy” is not a quantity and should not be given a numerical value.
The quantitative expression of accuracy should be in terms of uncertainty. “Good accuracy” or “more accurate”
implies small measurement error. Any given numerical value should be taken as indicative of this.
[SOURCE: ISO/IEC Guide 99:2007; 2.13, modified —Note 1 to entry modified; Notes 2 and 3 deleted.]
3.1.2
adjustment
set of operations carried out on a measuring system so that it provides prescribed indications
corresponding to given values of a quantity to be measured
Note 1 to entry: Adjustment should not be confused with calibration which is a prerequisite for adjustment.
Note 2 to entry: After adjustment, a recalibration is usually required.
[SOURCE: ISO/IEC Guide 99:2007; 3.11, modified — Note 1 deleted; Notes 1 and 2 to entry shortened.]
3.1.3
batch
proving batch
set of consecutive proving runs that is deemed to be necessary to derive both a mean value of volume,
meter factor (3.1.22) or K-factor (3.1.19), suitable for subsequent use and may also be used as an
indication of the repeatability of the measurements
Note 1 to entry: A batch may consist of multiple runs or one run (3.1.38) of a significant number of multiple passes
(3.1.24).
3.1.4
block-and-bleed valve
double-block-and-bleed valve
twin seal valve
high integrity valve with double seals and provision for detecting leakage past either seal
3.1.5
calibration
set of operations that establish, under specified conditions, the relationship between quantities
indicated by an instrument and the corresponding values realized by standards
Note 1 to entry: Calibration should not be confused with adjustment of a measuring system.
Note 2 to entry: Proving (3.1.27) is used in the oil industry and has the same meaning but can include a check of
the results against specified acceptance criteria.
1)
[SOURCE: ISO Guide 99:1993 ; 6.11, modified.]
3.1.6
calibrated volume
base volume
volume of a prover between detectors, or of a volumetric measure between a top and bottom datum, as
determined by calibration and expressed at standard conditions
1) Withdrawn.
ISO 7278-2:2022(E)
3.1.7
cavitation
phenomenon related to, and following, flashing (3.1.14), where vapour bubbles or voids form and
subsequently collapse or implode
Note 1 to entry: Cavitation causes significant measurement error and also potentially causes damage to the
pipes, valves and meter components through erosion.
3.1.8
cyclic distortion
periodic variation in the pulse frequency generated by a meter caused by mechanical asymmetry within
the meter and accessories
Note 1 to entry: See also intra-rotational linearity (3.1.18).
Note 2 to entry: Examples of accessories are calibrators and temperature compensators, mechanical or electronic.
3.1.9
detectors
devices set to directly, or indirectly, sense the passage of the displacer (3.1.11) hence indicating each
end of the calibrated volume
3.1.10
discrimination
ability of a measuring instrument to respond to small changes in the value of the input
3.1.11
displacer
sphere or a piston used to sweep out the calibrated volume between the detectors (3.1.9) of a pipe prover
3.1.12
correction factor
numerical factor by which the uncorrected result of a measurement at the measured conditions is
multiplied
Note 1 to entry: Correction factors to standard conditions are used to convert a volume at observed conditions to
the volume at another (standard) condition.
3.1.13
error
measured quantity value minus a reference quantity value
Note 1 to entry: Relative error is error divided by a reference value. This can be expressed as a percentage.
[SOURCE: ISO/IEC Guide 99:2007, 2.16, modified — Notes 1 and 2 deleted; new Note 1 to entry added;
and admitted terms "measurement error" and "error of measurement" deleted.]
3.1.14
flashing
phenomenon which occurs when the line pressure drops to, or below, the vapour pressure of the liquid,
allowing gas to appear from solution or through a component phase change
Note 1 to entry: Vapour pressure of the fluid can increase with increasing temperature.
Note 2 to entry: Flashing is often due to a local pressure drop caused by an increase in liquid velocity, and
generally causes significant measurement error.
Note 3 to entry: The free gas produced remains for a considerable distance downstream of the meter even if
pressure recovers.
ISO 7278-2:2022(E)
3.1.15
four-way valve
flow reversal valve
single high-integrity valve which reverses the directional flow passing through a bidirectional prover
3.1.16
gating
initiation and cessation of pulse totalization in a counter, triggered from an external event or signal
from detectors
3.1.17
interchange valve
sphere handling valve
high integrity mechanism to relocate the displacer (3.1.11) from the downstream end of a unidirectional
sphere prover to the launch position
Note 1 to entry: The valve enables continuous flow through the prover barrel while preventing flow across the
mechanism during a proving pass.
3.1.18
intra-rotational linearity
quantitative measure of the degree of regularity of spacing between the pulses produced by a flowmeter
at a constant flowrate
Note 1 to entry: This is generally expressed as the standard deviation of the pulse widths around the mean value.
Note 2 to entry: This may be referred to as inter-pulse deviations.
Note 3 to entry: Inter-rotational linearity is the regularity which repeats in a periodic or cyclic manner normally
attributed to the rotation of a meter internal mechanism. This may be referred to as pulse rate modulation.
3.1.19
K-factor
ratio of the number of pulses obtained from a meter to the quantity passed through the meter
3.1.20
end chamber
launch chamber
receive chamber
enlarged section at the ends of the pipe prover in which the displacer (3.1.11) rests prior to launch or
decelerates and comes to rest upon completion of a pass
3.1.21
linearity
total range of deviation of the accuracy curve from a constant value across a specified measurement
range
Note 1 to entry: The maximum deviation is based on the mean of derived values at any one flow point.
Note 2 to entry: The deviation is the largest minus the smallest value of mean values at each flowrate.
Note 3 to entry: Relative linearity is the range of values divided by a specified value, e.g. the independent linearity
as defined in ISO 11631.
3.1.22
meter factor
ratio of the quantity indicated by a reference standard to quantity indicated by a meter
3.1.23
nominal volume
design volume of a prover or volumetric measure
ISO 7278-2:2022(E)
3.1.24
pass
single movement of a displacer (3.1.11) between two detector actuations
3.1.25
pipe prover
displacement prover
device where a volume of fluid is displaced from a calibrated length of pipe and used to provide a
calibration reference for flowmeters
3.1.26
performance indicator
derived value which may be used to indicate the performance of the meter
Note 1 to entry: Examples of performance indicators are error (3.1.13), K-factor (3.1.19), or meter factor (3.1.22).
3.1.27
proving
calibration with comparison to specified acceptance criteria
Note 1 to entry: The term proving is used in the oil industry and is similar to verification.
Note 2 to entry: Proving is a calibration, sometimes of limited measurement range, according to methods
specified in standards, regulations or procedures, providing a determination of the errors of a device and
showing (proving) it performs to specified acceptance criteria.
3.1.28
pulse interpolation
means of increasing the effective resolution of the pulses output from a meter by multiplying the pulse
frequency or measuring the fraction of a pulse associated with the total collected across a time period
Note 1 to entry: The most common method employed is the double timing (chronometry) technique.
3.1.29
pulse interpolation divisor
ratio of the enhanced pulse frequency to the frequency of the pulses generated by the meter
Note 1 to entry: A pulse interpolation devisor is usually associated with the phase-locked-loop system of pulse
interpolation.
3.1.30
range
measuring range
set of values of flowrate for which the error (3.1.13) of a measuring instrument (flowmeter) is intended
to lie within specified limits
1)
[SOURCE: ISO Guide 99:1993 , 5.2]
3.1.31
range
range of values
difference between the maximum and minimum values of a set of values
Note 1 to entry: This can be expressed as a half range (±) number. Relative range is normally expressed as a
percentage of a specified value e.g. mean, minimum or other calculated value.
ISO 7278-2:2022(E)
3.1.32
reference condition
reference conditions of measurement
operating condition prescribed for evaluating the performance of a measuring instrument
Note 1 to entry: The reference conditions generally include reference values or reference ranges for the influence
quantities affecting the measuring instrument.
[SOURCE: ISO/IEC Guide 99:2007, 4.11, modified — Notes deleted; new Note 1 to entry added.]
3.1.33
reference measure
volumetric measure calibrated, used and maintained to provide traceability to other volume measures
and devices, including pipe provers (3.1.25) and reference flowmeters
Note 1 to entry: A reference measure can be calibrated gravimetrically (primary measure) or volumetrically by
means of a primary measure which itself
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