SIST EN ISO 5167-6:2022

Measurement of fluid flow by means of pressure differential devices inserted in circular cross-section conduits running full - Part 6: Wedge meters (ISO 5167-6:2022)

This document specifies the geometry and method of use (installation and operating conditions) of
wedge meters when they are inserted in a conduit running full to determine the flow rate of the fluid
flowing in the conduit.
NOTE 1 As the uncertainty of an uncalibrated wedge meter can be too large for a particular application, it
could be deemed essential to calibrate the flow meter according to Clause 7.
This document gives requirements for calibration which, if applied, are for use over the calibrated
Reynolds number range. Clause 7 could also be useful guidance for calibration of meters of similar
design but which fall outside the scope of this document.
It also provides background information for calculating the flow rate and is applicable in conjunction
with the requirements given in ISO 5167-1.
This document is applicable only to wedge meters in which the flow remains subsonic throughout the
measuring section and where the fluid can be considered as single-phase. Uncalibrated wedge meters
can only be used within specified limits of pipe size, roughness, β (or wedge ratio) and Reynolds number.
It is not applicable to the measurement of pulsating flow. It does not cover the use of uncalibrated wedge
meters in pipes whose internal diameter is less than 50 mm or more than 600 mm, or where the pipe
Reynolds numbers are below 1 × 104.
NOTE 2 A wedge meter has a primary element which consists of a wedge-shaped restriction of a specific
geometry. Alternative designs of wedge meters are available; however, at the time of writing there is insufficient
data to fully characterize these devices, and therefore these meters are calibrated in accordance with Clause 7.

Durchflussmessung von Fluiden mit Drosselgeräten in voll durchströmten Leitungen mit Kreisquerschnitt - Teil 6: Keil-Durchflussmesser (ISO 5167-6:2022)

Dieses Dokument legt die Geometrie und Anwendungsverfahren (Einbau  und Betriebsbedingungen) von in voll durchströmten Leitungen eingesetzten Keil Durchflussmessern fest, um den Durchfluss der Fluidströmung in der Leitung zu bestimmen.
ANMERKUNG 1 Da die Unsicherheit eines unkalibrierten Keil Durchflussmessers für eine bestimmte Anwendung zu groß sein kann, könnte es als erforderlich angesehen werden, den Durchflussmesser nach Abschnitt 7 zu kalibrieren.
Dieses Dokument enthält Anforderungen an die Kalibrierung, die, wenn sie angewendet werden, für den kalibrierten Bereich der Reynoldszahlen gelten. Abschnitt 7 könnte auch ein nützlicher Leitfaden für die Kalibrierung von Durchflussmessern ähnlicher Ausführung sein, die jedoch nicht in den Anwendungsbereich des vorliegenden Dokuments fallen.
Es gibt auch Hintergrundinformationen für die Durchflussberechnung und gilt in Verbindung mit den in ISO 5167 1 festgelegten Anforderungen.
Dieses Dokument ist nur auf Keil Durchflussmesser anwendbar, in denen die Strömung in allen Messquerschnitten im Unterschallbereich bleibt und das Fluid als einphasig betrachtet werden kann. Unkalibrierte Keil Durchflussmesser können nur innerhalb festgelegter Grenzen von Rohrweite, Rauheit β (oder Keilverhältnis) und Reynoldszahl angewendet werden. Es ist nicht für die Messung von pulsierender Strömung anwendbar. Es behandelt nicht die Anwendung von unkalibrierten Keil Durchflussmessern bei Rohren, deren Innendurchmesser geringer als 50 mm oder größer als 600 mm ist, oder wenn die Rohr Reynoldszahlen unter 1 × 104 liegen.
ANMERKUNG 2 Ein Keil Durchflussmesser verfügt über ein Primärelement, das aus einer keilförmigen Verengung mit spezifischer Geometrie besteht. Es stehen alternative Ausführungen von Keil Durchflussmessern zur Verfügung; zum Zeitpunkt der Erstellung der Norm gibt es jedoch nicht genügend Daten, um diese Geräte vollständig zu beschreiben, und deshalb werden diese Durchflussmesser nach Abschnitt 7 kalibriert.

Mesurage de débit des fluides au moyen d'appareils déprimogènes insérés dans des conduites en charge de section circulaire - Partie 6: Débitmètres à coin (ISO 5167-6:2022)

Le présent document spécifie la géométrie et le mode d’emploi (conditions d’installation et d’utilisation) de débitmètres à coin insérés dans une conduite en charge dans le but de déterminer le débit du fluide s’écoulant dans cette conduite.
NOTE 1    Étant donné que l’incertitude d’un débitmètre à coin non étalonné risque d’être trop grande pour une application particulière, l’étalonnage du débitmètre conformément à l’Article 7 peut être considéré comme essentiel.
Le présent document fournit des exigences relatives à l’étalonnage qui, si elles sont appliquées, sont destinées à être utilisées sur la plage des nombres de Reynolds qui a été étalonnée. L’Article 7 peut également fournir des recommandations utiles relatives à l’étalonnage des appareils de mesure de conception similaire, mais qui n’entrent pas dans le domaine d’application du présent document.
Il fournit également des informations de fond nécessaires au calcul du débit et il est applicable conjointement avec les exigences stipulées dans l’ISO 5167‑1.
Le présent document est applicable uniquement aux débitmètres à coin pour lesquels l’écoulement reste subsonique dans tout le tronçon de mesure et où le fluide peut être considéré comme monophasique. Les débitmètres à coin non étalonnés ne peuvent être utilisés que dans des limites spécifiées de diamètre de conduite, de rugosité, de valeur de β (ou rapport du coin) et de nombre de Reynolds. Ce document n’est pas applicable au mesurage d’un écoulement pulsé. Il ne couvre pas l’utilisation de débitmètres à coin non étalonnés dans des conduites dont le diamètre intérieur est inférieur à 50 mm ou supérieur à 600 mm, ni les cas où les nombres de Reynolds associés à la tuyauterie sont inférieurs à 1 × 104.
NOTE 2    Un débitmètre à coin comporte un élément primaire composé d’une restriction en forme de coin de géométrie spécifique. D’autres conceptions de débitmètres à coin sont possibles; cependant, au moment de la rédaction du présent document, les données permettant de caractériser complètement ces appareils étaient insuffisantes et ces derniers sont donc étalonnés conformément à l’Article 7.

Merjenje pretoka fluida na osnovi tlačne razlike, povzročene z napravo, vstavljeno v polno zapolnjen vod s krožnim prerezom - 6. del: Merilniki klinov (ISO 5167-6:2022)

General Information

• Status: Published
• Public Enquiry End Date: 06-Mar-2022
• Publication Date: 20-Nov-2022
• ICS: 17.120.10 - Flow in closed conduits
• Technical Committee: IMIN - Measurement instruments
• Current Stage: 6060 - National Implementation/Publication (Adopted Project)
• Start Date: 10-Nov-2022
• Due Date: 15-Jan-2023
• Completion Date: 21-Nov-2022
• Ref Project: EN ISO 5167-6:2022 - Measurement of fluid flow by means of pressure differential devices inserted in circular cross-section conduits running full - Part 6: Wedge meters (ISO 5167-6:2022)

Relations

• Replaces: SIST EN ISO 5167-6:2019 - Measurement of fluid flow by means of pressure differential devices inserted in circular cross-section conduits running full - Part 6: Wedge meters (ISO 5167-6:2019)
• Effective Date: 09-Nov-2022

Standards Content (Sample)

SLOVENSKI STANDARD
SIST EN ISO 5167-6:2022
01-december-2022
Nadomešča:
SIST EN ISO 5167-6:2019
Merjenje pretoka fluida na osnovi tlačne razlike, povzročene z napravo, vstavljeno
v polno zapolnjen vod s krožnim prerezom - 6. del: Merilniki klinov (ISO 5167-
6:2022)
Measurement of fluid flow by means of pressure differential devices inserted in circular
cross-section conduits running full - Part 6: Wedge meters (ISO 5167-6:2022)
Durchflussmessung von Fluiden mit Drosselgeräten in voll durchströmten Leitungen mit
Kreisquerschnitt - Teil 6: Keil-Durchflussmesser (ISO 5167-6:2022)
Mesurage de débit des fluides au moyen d'appareils déprimogènes insérés dans des
conduites en charge de section circulaire - Partie 6: Débitmètres à coin (ISO 5167-
6:2022)
Ta slovenski standard je istoveten z: EN ISO 5167-6:2022
ICS:
17.120.10 Pretok v zaprtih vodih Flow in closed conduits
SIST EN ISO 5167-6:2022 en,fr,de
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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SIST EN ISO 5167-6:2022

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SIST EN ISO 5167-6:2022


EN ISO 5167-6
EUROPEAN STANDARD

NORME EUROPÉENNE

November 2022
EUROPÄISCHE NORM
ICS 17.120.10 Supersedes EN ISO 5167-6:2019
English Version

Measurement of fluid flow by means of pressure
differential devices inserted in circular cross-section
conduits running full - Part 6: Wedge meters (ISO 5167-
6:2022)
Mesurage de débit des fluides au moyen d'appareils Durchflussmessung von Fluiden mit Drosselgeräten in
déprimogènes insérés dans des conduites en charge de voll durchströmten Leitungen mit Kreisquerschnitt -
section circulaire - Partie 6: Débitmètres à coin (ISO Teil 6: Keil-Durchflussmesser (ISO 5167-6:2022)
5167-6:2022)
This European Standard was approved by CEN on 25 September 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 5167-6:2022 E
worldwide for CEN national Members.

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SIST EN ISO 5167-6:2022
EN ISO 5167-6:2022 (E)
Contents Page
European foreword . 3

2

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SIST EN ISO 5167-6:2022
EN ISO 5167-6:2022 (E)
European foreword
This document (EN ISO 5167-6:2022) has been prepared by Technical Committee ISO/TC 30
"Measurement of fluid flow in closed conduits" in collaboration with CCMC.
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 5167-6:2019.
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 5167-6:2022 has been approved by CEN as EN ISO 5167-6:2022 without any
modification.


3

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SIST EN ISO 5167-6:2022

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SIST EN ISO 5167-6:2022
INTERNATIONAL ISO
STANDARD 5167-6
Second edition
2022-10
Measurement of fluid flow by means of
pressure differential devices inserted
in circular cross-section conduits
running full —
Part 6:
Wedge meters
Mesurage de débit des fluides au moyen d'appareils déprimogènes
insérés dans des conduites en charge de section circulaire —
Partie 6: Débitmètres à coin
Reference number
ISO 5167-6:2022(E)
© ISO 2022

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SIST EN ISO 5167-6:2022
ISO 5167-6:2022(E)
COPYRIGHT PROTECTED DOCUMENT
© 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
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: [phone]
Email: [e-mail]
Website: www.iso.org
Published in Switzerland
ii
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SIST EN ISO 5167-6:2022
ISO 5167-6:2022(E)
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Principles of the method of measurement and computation . 2
5 Wedge meters .3
5.1 Field of application . 3
5.2 General shape . 4
5.3 Material and manufacture . 5
5.4 Pressure tappings . 5
5.5 Discharge coefficient, C . 6
5.5.1 Limits of use . 6
5.5.2 Discharge coefficient of the wedge meter . 6
5.6 Expansibility [expansion] factor, ε . 6
5.7 Uncertainty of the discharge coefficient, C . 7
5.8 Uncertainty of the expansibility [expansion] factor, ε . 7
5.9 Pressure loss . 7
6 Installation requirements .7
6.1 General . 7
6.2 Minimum upstream and downstream straight lengths for installations between
various fittings and the wedge meter . 7
6.3 Additional specific installation requirements for wedge meters . 8
6.3.1 Circularity and cylindricality of the pipe . 8
6.3.2 Roughness of the upstream and downstream pipe. 8
6.3.3 Positioning of a thermowell . 8
6.3.4 Bidirectional wedge meters . 9
7 Flow calibration of wedge meters .9
7.1 General . 9
7.2 Test facility . 9
7.3 Meter installation . . 9
7.4 Design of the test programme . 9
7.5 Reporting the calibration results . 10
7.6 Uncertainty analysis of the calibration . 10
7.6.1 General . 10
7.6.2 Uncertainty of the test facility . 10
7.6.3 Uncertainty of the discharge coefficient of the wedge meter . 10
Annex A (informative) Table of expansibility [expansion] factor .11
2
Annex B (informative) Use of Kd parameter .12
Bibliography .13
iii
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SIST EN ISO 5167-6:2022
ISO 5167-6:2022(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 on 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 the following
URL: www.iso.org/iso/foreword.html.
This document was prepared by Technical Committee ISO/TC 30, Measurement of fluid flow in closed
conduits, Subcommittee SC 2, Pressure differential devices, in collaboration with the European Committee
for Standardization (CEN) Technical Committee CEN/SS F05, Measuring instruments, in accordance with
the Agreement on technical cooperation between ISO and CEN (Vienna Agreement).
This second edition cancels and replaces the first edition (ISO 5167-6:2019), which has been technically
revised.
The main changes are as follows:
— this document is consistent with ISO/IEC Guide 98-3;
— an error in Annex B has been corrected;
— the expansibility uncertainty is given as a relative uncertainty for ease of use with Part 1 (the
calculated flow rate uncertainty is unchanged).
A list of all the parts in the ISO 5167 series can be found on the ISO website.
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SIST EN ISO 5167-6:2022
ISO 5167-6:2022(E)
Introduction
ISO 5167, consisting of six parts, covers the geometry and method of use (installation and operating
conditions) of orifice plates, nozzles, Venturi tubes, cone and wedge meters when they are inserted in a
conduit running full to determine the flow rate of the fluid flow in the conduit. It also gives necessary
information for calculating the flow rate and its associated uncertainty.
ISO 5167 (all parts) is applicable only to pressure differential devices in which the flow remains
subsonic throughout the measuring section and where the fluid can be considered as single-phase, but
it is not applicable to the measurement of pulsating flow. Furthermore, each of these devices can only
be used within specified limits of pipe size and Reynolds number, Re.
ISO 5167 (all parts) deals with devices for which direct calibration experiments have been made,
sufficient in number, spread and quality to enable coherent systems of application to be based on their
results and coefficients to be given with certain predictable limits of uncertainty. However, for wedge
meters calibrated in accordance with Clause 7, a wider range of pipe size, β and Reynolds number can
be considered.
The devices introduced into the pipe are called primary devices. The term primary device also includes
the pressure tappings. All other instruments or devices required to facilitate the instrument readings
are known as secondary devices, and the flow computer that receives these readings and performs
the algorithms is known as a tertiary device. ISO 5167 (all parts) covers primary devices; secondary
devices (see ISO 2186) and tertiary devices will be mentioned only occasionally.
Aspects of safety are not dealt with in ISO 5167-1 to ISO 5167-6. It is the responsibility of the user to
ensure that the system meets applicable safety regulations.
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SIST EN ISO 5167-6:2022

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SIST EN ISO 5167-6:2022
INTERNATIONAL STANDARD ISO 5167-6:2022(E)
Measurement of fluid flow by means of pressure
differential devices inserted in circular cross-section
conduits running full —
Part 6:
Wedge meters
1 Scope
This document specifies the geometry and method of use (installation and operating conditions) of
wedge meters when they are inserted in a conduit running full to determine the flow rate of the fluid
flowing in the conduit.
NOTE 1 As the uncertainty of an uncalibrated wedge meter can be too large for a particular application, it
could be deemed essential to calibrate the flow meter according to Clause 7.
This document gives requirements for calibration which, if applied, are for use over the calibrated
Reynolds number range. Clause 7 could also be useful guidance for calibration of meters of similar
design but which fall outside the scope of this document.
It also provides background information for calculating the flow rate and is applicable in conjunction
with the requirements given in ISO 5167-1.
This document is applicable only to wedge meters in which the flow remains subsonic throughout the
measuring section and where the fluid can be considered as single-phase. Uncalibrated wedge meters
can only be used within specified limits of pipe size, roughness, β (or wedge ratio) and Reynolds number.
It is not applicable to the measurement of pulsating flow. It does not cover the use of uncalibrated wedge
meters in pipes whose internal diameter is less than 50 mm or more than 600 mm, or where the pipe
4
Reynolds numbers are below 1 × 10 .
NOTE 2 A wedge meter has a primary element which consists of a wedge-shaped restriction of a specific
geometry. Alternative designs of wedge meters are available; however, at the time of writing there is insufficient
data to fully characterize these devices, and therefore these meters are calibrated in accordance with Clause 7.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements of this document. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any amendments) applies.
ISO 4006, Measurement of fluid flow in closed conduits — Vocabulary and symbols
ISO 5167-1, Measurement of fluid flow by means of pressure differential devices inserted in circular cross-
section conduits running full — Part 1: General principles and requirements
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 4006, ISO 5167-1 and the
following apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
1
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SIST EN ISO 5167-6:2022
ISO 5167-6:2022(E)
— IEC Electropedia: available at https:// www .electropedia .org/
3.1
wedge gap
h
maximum gap between the apex of the wedge element and the pipe wall, in the plane perpendicular to
the pipe axis
Note 1 to entry: See Figure 1.
3.2
wedge ratio
ratio of the wedge gap (3.1) to the meter inlet diameter, D
Note 1 to entry: See ISO 4006:1991, Clause 2, for the meter inlet diameter, D.
3.3
wedge throat area
A
t
minimum cross-sectional open area of the wedge meter
4 Principles of the method of measurement and computation
The principle of the method of measurement is based on the installation of the wedge meter into a
pipeline in which a fluid is running full. Flow through a wedge meter produces a differential pressure
between the upstream and downstream tappings.
The mass flow rate can be determined by the following formulae:
C π
2
q = εβDp2Δ ρ (1)
()
m 1
4 4
1−β
and
4A
t
β = (2)
2
πD
A larger β corresponds to a larger wedge gap height, h (see Figure 1), and therefore a larger wedge
throat area, A . The value of β can be calculated using Formula (3):
t
2
 
1 2h 2h h h
     
 
β =−arccos 1 −−21 ×− (3)
     
π  D   D  D D
 
 
NOTE For example, h/D = 0,5 does not correspond to β = 0,5, but to β = √0,5 ≈ 0,707. β = 0,5 corresponds to
h/D ≈ 0,298.
2
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SIST EN ISO 5167-6:2022
ISO 5167-6:2022(E)

a
Direction of flow.
Figure 1 — Wedge meter showing different values of wedge ratio
The uncertainty limits can be calculated using the procedure given in ISO 5167-1:2022, Clause 8.
Similarly, the value of the volume flow rate can be calculated since
q
m
q = (4)
V
ρ
where ρ is the fluid density at the temperature and pressure for which the volume is stated.
Computation of the flow rate, which is a purely arithmetic process, is performed by replacing the
different items on the right-hand side of Formula (1) by their numerical values. Formula (5) (or the
computed values in Table A.1) gives wedge meter expansibility factors, ε. The values in Table A.1 are
not intended for precise interpolation. Extrapolation is not permitted. However, for a meter calibrated
according to Clause 7, the discharge coefficient, C, is generally related to the Reynolds number, Re, which
is itself related to q , and has to be obtained by iteration (see ISO 5167-1:2022, Annex A, for guidance
m
regarding the choice of iteration procedure and initial estimates).
The wedge gap, h, and the pipe diameter, D, mentioned in Formula (3) are the values of the lengths at
working conditions. Measurements taken at any other conditions should be corrected for any possible
expansion or contraction of the primary device and the pipe due to the values of the temperature and
pressure of the fluid during the measurement.
As the wedge meter flow rate calculation is particularly sensitive to the pipe diameter and wedge
gap values used, the user shall ensure that these are correctly entered into the flow computation
calculations. The measured internal diameter shall be used rather than a nominal value.
It is necessary to know the density and the viscosity of the fluid at working conditions. In the case
of a compressible fluid, it is also necessary to know the isentropic exponent of the fluid at working
conditions.
5 Wedge meters
5.1 Field of application
Uncalibrated wedge meters can be used in pipes with diameters between 50 mm and 600 mm and with
0,377 ≤ β ≤ 0,791 (wedge ratio 0,2 ≤ h/D ≤ 0,6). Wedge meters with β > 0,791 (h/D > 0,6) or β < 0,377
(h/D < 0,2) are not normally manufactured.
There are limits to the roughness which are addressed in 5.2.3, 5.2.7, and 6.3.2. There are limits to the
Reynolds number which are addressed in 5.5.2.
3
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SIST EN ISO 5167-6:2022
ISO 5167-6:2022(E)
5.2 General shape
5.2.1 The wedge meter as shown in Figure 2 comprises (listed in the direction of flow) an entrance
cylinder, an upstream pressure tapping, a pipe section including the wedge element, a downstream
pressure tapping, and an exit cylinder. The form of the pressure tappings is described in 5.4.
5.2.2 The diameter D shall be measured at the plane of the upstream tapping. The number of
measurements shall be a minimum of four equally spaced around the pipe internal circumference. The
arithmetic mean value of these measurements shall be taken as the value of D in the calculations.
The minimum entrance cylinder length shall be 0,5D. The minimum exit cylinder length shall be 0,5D.
Diameters shall also be measured in planes other than the plane of the upstream pressure tapping.
No diameter along the wedge meter shall differ by more than 0,4 % from the value of the mean diameter.
This requirement is satisfied when the difference in the length of any of the measured diameters
complies with the said requirement with respect to the mean of the measured diameters.
Key
1 meter body
2 meter body centreline
3 wedge element
4 wedge apex
5 high pressure tapping
6 low pressure tapping
a
Direction of flow.
Figure 2 — Geometric profile of wedge meter
5.2.3 The internal surface of the pipe section between the planes of the upstream and downstream
tappings shall be clean and smooth, and the roughness criterion, Ra, should be as small as possible and
−3
shall be less than 10 D.
5.2.4 The wedge plane angle, θ , shall be 90° ± 2° at all points of intersection along the span of the
c
wedge apex. The span of the wedge apex shall be perpendicular to the centreline of the tappings and
also to the centreline of the wedge meter.
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SIST EN ISO 5167-6:2022
ISO 5167-6:2022(E)
5.2.5 The radius of curvature of the wedge apex, R , as shown in Figure 3, shall be less than or equal
w
to 1 mm along the span of the wedge apex.
Figure 3 — Radius of curvature, R , at the wedge apex
w
5.2.6 The upstream external angle, θ , and downstream external angle, θ , of the wedge shall be
1 2
measured and shall both be equal to 135° ± 2°.
5.2.7 The wedge surface shall be clean and smooth, and the roughness criterion, Ra, shall be as small
−3
as possible and shall always be less than 10 D.
5.2.8 Where the wedge is attached to the meter body by welding, the manufacturer should take care
to minimize the size of the weld beads within the limits required for structural integrity.
5.2.9 Where the wedge is attached to the meter body by welding, the manufacturer shall ensure there
is no intrusion of the weld into the design throat area.
5.3 Material and manufacture
5.3.1 The wedge meter may be manufactured from any material and using any construction
technique, provided that the wedge meter is in accordance with the foregoing description and will
remain so during use.
5.3.2 Hollow wedge element designs shall include a pressure equalization system to ensure the
structural stability of the wedge under rapid pressure changes.
5.4 Pressure tappings
5.4.1 The upstream tapping shall be made either in the form of a pipe wall pressure tapping or a large
bore branch tapping. It is recommended that the tappings be as small as compatible with the fluid (for
example, with its viscosity and contaminants).
The large bore tapping design may be considered to be more applicable for slurry, corrosive fluids, or
fluids which require diaphragm seals.
5.4.2 The centreline of the tappings shall be perpendicular to and pass through the centreline of the
meter body (see Figure 2). The centreline of the tappings shall also be perpendicular to the line of the
wedge apex ±2°. The tappings shall be located on the same side of the meter body as the wedge element.
5.4.3 The centreline of the tappings shall be located 1D ± 0,02D from the nearest point of the w
...

SLOVENSKI STANDARD
oSIST prEN ISO 5167-6:2022
01-februar-2022
Merjenje pretoka fluida na osnovi tlačne razlike, povzročene z napravo, vstavljeno
v polno zapolnjen vod s krožnim prerezom - 6. del: Merilniki klinov (ISO/DIS 5167-
6:2021)
Measurement of fluid flow by means of pressure differential devices inserted in circular
cross-section conduits running full - Part 6: Wedge meters (ISO/DIS 5167-6:2021)
Durchflussmessung von Fluiden mit Drosselgeräten in voll durchströmten Leitungen mit
Kreisquerschnitt - Teil 6: Keil-Durchflussmesser (ISO/DIS 5167‑6:2021)
Mesure de débit des fluides au moyen d'appareils déprimogènes insérés dans des
conduites en charge de section circulaire - Partie 6: Débitmètres à coin (ISO/DIS 5167-
6:2021)
Ta slovenski standard je istoveten z: prEN ISO 5167-6
ICS:
17.120.10 Pretok v zaprtih vodih Flow in closed conduits
oSIST prEN ISO 5167-6:2022 en,fr,de
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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oSIST prEN ISO 5167-6:2022

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oSIST prEN ISO 5167-6:2022
DRAFT INTERNATIONAL STANDARD
ISO/DIS 5167-6
ISO/TC 30/SC 2 Secretariat: BSI
Voting begins on: Voting terminates on:
2021-12-13 2022-03-07
Measurement of fluid flow by means of pressure
differential devices inserted in circular cross-section
conduits running full —
Part 6:
Wedge meters
Mesure de débit des fluides au moyen d'appareils déprimogènes insérés dans des conduites en charge de
section circulaire —
Partie 6: Débitmètres à coin
ICS: 17.120.10
This document is circulated as received from the committee secretariat.
THIS DOCUMENT IS A DRAFT CIRCULATED
FOR COMMENT AND APPROVAL. IT IS
ISO/CEN PARALLEL PROCESSING
THEREFORE SUBJECT TO CHANGE AND MAY
NOT BE REFERRED TO AS AN INTERNATIONAL
STANDARD UNTIL PUBLISHED AS SUCH.
IN ADDITION TO THEIR EVALUATION AS
BEING ACCEPTABLE FOR INDUSTRIAL,
TECHNOLOGICAL, COMMERCIAL AND
USER PURPOSES, DRAFT INTERNATIONAL
STANDARDS MAY ON OCCASION HAVE TO
BE CONSIDERED IN THE LIGHT OF THEIR
POTENTIAL TO BECOME STANDARDS TO
WHICH REFERENCE MAY BE MADE IN
Reference number
NATIONAL REGULATIONS.
ISO/DIS 5167-6:2021(E)
RECIPIENTS OF THIS DRAFT ARE INVITED
TO SUBMIT, WITH THEIR COMMENTS,
NOTIFICATION OF ANY RELEVANT PATENT
RIGHTS OF WHICH THEY ARE AWARE AND TO
PROVIDE SUPPORTING DOCUMENTATION. © ISO 2021

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oSIST prEN ISO 5167-6:2022
ISO/DIS 5167-6:2021(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2021
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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Phone: [phone]
Email: [e-mail]
Website: www.iso.org
Published in Switzerland
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oSIST prEN ISO 5167-6:2022
ISO/DIS 5167-6:2021(E)
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 2
4 Principles of the method of measurement and computation . 2
5 Wedge meters .3
5.1 Field of application . 3
5.2 General shape . 4
5.3 Material and manufacture . 5
5.4 Pressure tappings . 5
5.5 Discharge coefficient, C . 6
5.5.1 Limits of use . 6
5.5.2 Discharge coefficient of the wedge meter . 6
5.6 Expansibility [expansion] factor, ε . 7
5.7 Uncertainty of the discharge coefficient, C . 7
5.8 Uncertainty of the expansibility [expansion] factor, ε . 7
5.9 Pressure loss . 7
6 Installation requirements .7
6.1 General . 7
6.2 Minimum upstream and downstream straight lengths for installations between
various fittings and the wedge meter . 8
6.3 Additional specific installation requirements for wedge meters . 8
6.3.1 Circularity and cylindricality of pipes upstream and downstream of the
wedge meter . 8
6.3.2 Roughness of the upstream and downstream pipe. 9
6.3.3 Positioning of a thermowell . 9
6.3.4 Bidirectional wedge meters . 9
7 Flow calibration of wedge meters .9
7.1 General . 9
7.2 Test facility . 9
7.3 Meter installation . . 9
7.4 Design of the test programme . 10
7.5 Reporting the calibration results . 10
7.6 Uncertainty analysis of the calibration . 10
7.6.1 General . 10
7.6.2 Uncertainty of the test facility . 10
7.6.3 Uncertainty of the discharge coefficient of the wedge meter . 10
Annex A (informative) Table of expansibility [expansion] factor .11
2
Annex B (informative) Use of Kd parameter .12
Bibliography .13
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oSIST prEN ISO 5167-6:2022
ISO/DIS 5167-6:2021(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 on 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 the following
URL: www.iso.org/iso/foreword.html.
This document was prepared by Technical Committee ISO/TC 30, Measurement of fluid flow in closed
conduits, Subcommittee SC 2, Pressure differential devices. This second edition cancels and replaces the
first edition (ISO 5167-6:2019), which has been technically revised.
A list of all the parts in the ISO 5167 series can be found on the ISO website.
iv
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oSIST prEN ISO 5167-6:2022
ISO/DIS 5167-6:2021(E)
Introduction
ISO 5167, divided into six parts, covers the geometry and method of use (installation and operating
conditions) of orifice plates, nozzles, Venturi tubes, cone and wedge meters when they are inserted in a
conduit running full to determine the flow rate of the fluid flow in the conduit. It also gives necessary
information for calculating the flow rate and its associated uncertainty.
ISO 5167 is applicable only to pressure differential devices in which the flow remains subsonic
throughout the measuring section and where the fluid can be considered as single-phase, but it is not
applicable to the measurement of pulsating flow. Furthermore, each of these devices can only be used
within specified limits of pipe size and Reynolds number.
ISO 5167 deals with devices for which direct calibration experiments have been made, sufficient
in number, spread and quality to enable coherent systems of application to be based on their results
and coefficients to be given with certain predictable limits of uncertainty. However, for wedge meters
calibrated in accordance with Clause 7, a wider range of pipe size, β and Reynolds number can be
considered.
The devices introduced into the pipe are called 'primary devices'. The term primary device also
includes the pressure tappings. All other instruments or devices required for the measurement are
1)
known as 'secondary devices'. ISO 5167 covers primary devices; secondary devices are mentioned
only occasionally.
ISO 5167 is divided into the following six parts.
a) ISO 5167-1 gives general terms and definitions, symbols, principles and requirements as well as
methods of measurement and uncertainty that are to be used in conjunction with Part 2 to Part 6 of
ISO 5167.
b) ISO 5167-2 specifies orifice plates, which can be used with corner pressure tappings, D and D/2
2)
pressure tappings , and flange pressure tappings.
3)
c) ISO 5167-3 specifies ISA 1932 nozzles , long radius nozzles and Venturi nozzles, which differ in
shape and in the position of the pressure tappings. Throat-tapped long-radius nozzles are included.
4)
d) ISO 5167-4 specifies classical Venturi tubes .
e) ISO 5167-5 specifies cone meters.
f) ISO 5167-6 specifies wedge meters.
[1] [4]
1) See ISO 2186 and also ISO/TR 9464 .
2) Orifice plates with 'vena contracta' pressure tappings are not considered in ISO 5167.
3) ISA is the abbreviation for the International Federation of the National Standardizing Associations, which was
succeeded by ISO in 1946.
4) In the USA the classical Venturi tube is sometimes called the Herschel Venturi tube.
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oSIST prEN ISO 5167-6:2022
DRAFT INTERNATIONAL STANDARD ISO/DIS 5167-6:2021(E)
Measurement of fluid flow by means of pressure
differential devices inserted in circular cross-section
conduits running full —
Part 6:
Wedge meters
1 Scope
This document specifies the geometry and method of use (installation and operating conditions) of
wedge meters when they are inserted in a conduit running full to determine the flow rate of the fluid
flowing in the conduit.
NOTE 1 As the uncertainty of an uncalibrated wedge meter can be too large for a particular application, it
could be deemed essential to calibrate the flow meter according to Clause 7.
This document gives requirements for calibration which, if applied, are for use over the calibrated
Reynolds number range. Clause 7 could also be useful guidance for calibration of meters of similar
design but which fall outside the scope of this document.
It also provides background information for calculating the flow rate and is applicable in conjunction
with the requirements given in ISO 5167-1.
This document is applicable only to wedge meters in which the flow remains subsonic throughout
the measuring section and where the fluid can be considered as single-phase. Uncalibrated wedge
meters can only be used within specified limits of pipe size, roughness, beta (or wedge ratio) and
Reynolds number. It is not applicable to the measurement of pulsating flow. It does not cover the use of
uncalibrated wedge meters in pipes whose internal diameter is less than 50 mm or more than 600 mm,
4
or where the pipe Reynolds numbers are below 1 × 10 .
NOTE 2 A wedge meter has a primary element which consists of a wedge-shaped restriction of a specific
geometry. Alternative designs of wedge meters are available; however, at the time of writing there is insufficient
data to fully characterize these devices, and therefore these meters are calibrated in accordance with Clause 7.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements of this document. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any amendments) applies.
ISO 4006, Measurement of fluid flow in closed conduits — Vocabulary and symbols
ISO 5167-1, Measurement of fluid flow by means of pressure differential devices inserted in circular cross-
section conduits running full — Part 1: General principles and requirements
ISO 5168, Measurement of fluid flow — Procedures for the evaluation of uncertainties
ISO/IEC 17025, General requirements for the competence of testing and calibration laboratories
ISO/IEC Guide 98-3, Uncertainty of measurement — Part 3: Guide to the expression of uncertainty in
measurement (GUM: 1995)
1
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oSIST prEN ISO 5167-6:2022
ISO/DIS 5167-6:2021(E)
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 4006, ISO 5167-1 and the
following apply.
ISO and IEC maintain terminological 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/
3.1
wedge gap
h
maximum gap between the apex of the wedge element and the pipe wall, in the plane perpendicular to
the pipe axis
Note 1 to entry: See Figure 1.
3.2
wedge ratio
ratio of the wedge gap to the meter inlet diameter, D
Note 1 to entry: See ISO 4006:1991, Clause 2, for the meter inlet diameter, D.
3.3
wedge throat area
A
t
minimum cross-sectional open area of the wedge meter
4 Principles of the method of measurement and computation
The principle of the method of measurement is based on the installation of the wedge meter into a
pipeline in which a fluid is running full. Flow through a wedge meter produces a differential pressure
between the upstream and downstream tappings.
The mass flow rate can be determined by the following formulae:
C π
2
q = εβDp2Δ ρ (1)
()
m 1
4
4
1−β
and
4A
t
β = (2)
2
πD
A larger β corresponds to a larger wedge gap height, h (see Figure 1), and therefore a larger throat area
A . The value of β can be calculated using Formula (3):
t
 2 
1  2h  2h h  h 
 
β =−arccos 1 −−21 ×− (3)
     
 
π D D D D
     
 
NOTE For example, h/D = 0,5 does not correspond to β = 0,5, but to β = √0,5 ≈ 0,707. β = 0,5 corresponds to
h/D ≈ 0,298.
2
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oSIST prEN ISO 5167-6:2022
ISO/DIS 5167-6:2021(E)
Key
a
Flow.
Figure 1 — Wedge meter showing different values of wedge ratio
The uncertainty limits can be calculated using the procedure given in ISO 5167-1:2003, Clause 8.
Similarly, the value of the volume flow rate can be calculated since
q
m
q = (4)
V
ρ
where ρ is the fluid density at the temperature and pressure for which the volume is stated.
Computation of the flow rate, which is a purely arithmetic process, is performed by replacing the
different items on the right-hand side of Formula (1) by their numerical values. Formula (5) (or the
computed values in Table A.1) gives wedge meter expansibility factors (ε). The values in Table A.1 are
not intended for precise interpolation. Extrapolation is not permitted. However, for a meter calibrated
according to Clause 7, the coefficient of discharge, C, is generally related to the Reynolds number, Re,
which is itself related to q , and has to be obtained by iteration (see ISO 5167-1:2003, Annex A, for
m
guidance regarding the choice of iteration procedure and initial estimates).
The wedge gap, h, and the pipe diameter, D, mentioned in Formula (3) are the values of the lengths at
working conditions. Measurements taken at any other conditions should be corrected for any possible
expansion or contraction of the primary device and the pipe due to the values of the temperature and
pressure of the fluid duri
...