Measurement of fluid flow by means of pressure differential devices inserted in circular cross-section conduits running full - Part 6: Wedge meters (ISO/FDIS 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, 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, 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/FDIS 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/FDIS 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 pourrait 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 préconisations utiles pour 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 bêta (ou rapport du coin) et de nombre de Reynolds. Il 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 rapportés 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/FDIS 5167-6:2022)

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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.
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© ISO 2021 – All rights reserved
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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

Annex B (informative) Use of Kd parameter ...........................................................................................................................................12

Bibliography .............................................................................................................................................................................................................................13

iii
© ISO 2021 – All rights reserved
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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.
© ISO 2021 – All rights reserved
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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

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

pressure tappings , and flange pressure tappings.

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.

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.

© ISO 2021 – All rights reserved
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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 5167-6:2021(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,

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)
© ISO 2021 – All rights reserved
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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

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
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
q = εβDp2Δ ρ (1)
m 1
1−β
and
β = (2)

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):
 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.
© ISO 2021 – All rights reserved
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oSIST prEN ISO 5167-6:2022
ISO/DIS 5167-6:2021(E)
Key
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 = (4)

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

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
...

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