EN ISO 5167-6:2019

SLOVENSKI STANDARD
01-december-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-
6:2019)
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)
Durchflussmessung von Fluiden mit Drosselgeräten in voll durchströmten Leitungen mit
Kreisquerschnitt - Teil 6: Keil-Durchflussmesser (ISO 5167-6:2019)
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 5167-
6:2019)
Ta slovenski standard je istoveten z: EN ISO 5167-6:2019
ICS:
17.120.10 Pretok v zaprtih vodih Flow in closed conduits
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EN ISO 5167-6
EUROPEAN STANDARD
NORME EUROPÉENNE
October 2019
EUROPÄISCHE NORM
ICS 17.120.10
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-
6:2019)
Mesure 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 5167-6:2019)
5167-6:2019)
This European Standard was approved by CEN on 23 September 2019.

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, Turkey 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
© 2019 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 5167-6:2019 E
worldwide for CEN national Members.

Contents Page
European foreword . 3

European foreword
The text of ISO 5167-6:2019 has been prepared by Technical Committee ISO/TC 30 "Measurement of
fluid flow in closed conduits” of the International Organization for Standardization (ISO) and has been
taken over as EN ISO 5167-6:2019 by 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 April 2020, and conflicting national standards shall be
withdrawn at the latest by April 2020.
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.
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, Turkey and the
United Kingdom.
Endorsement notice
The text of ISO 5167-6:2019 has been approved by CEN as EN ISO 5167-6:2019 without any
modification.
INTERNATIONAL ISO
STANDARD 5167-6
First edition
2019-02
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
Reference number
ISO 5167-6:2019(E)
©
ISO 2019
ISO 5167-6:2019(E)
© ISO 2019
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
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Published in Switzerland
ii © ISO 2019 – All rights reserved

ISO 5167-6:2019(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. 8
6.1 General . 8
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 wedge meter .10
Annex A (informative) Table of expansibility [expansion] factor .11
Annex B (informative) Use of Kd parameter .12
Bibliography .13
ISO 5167-6:2019(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.
A list of all the parts in the ISO 5167 series can be found on the ISO website.
iv © ISO 2019 – All rights reserved

ISO 5167-6:2019(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) Part 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) Part 2 specifies requirements for orifice plates, which can be used with corner pressure tappings, D
2)
and D/2 pressure tappings , and flange pressure tappings.
3)
c) Part 3 specifies requirements for ISA 1932 nozzles , long radius nozzles and Venturi nozzles, which
differ in shape and in the position of the pressure tappings.
4)
d) Part 4 specifies requirements for classical Venturi tubes .
e) Part 5 specifies requirements for cone meters, and includes a section on calibration.
f) Part 6 specifies requirements for wedge meters, and includes a section on calibration.
NOTE This document is complementary to ISO 5167-1:2003, ISO 5167-2:2003, ISO 5167-3:2003,
ISO 5167-4:2003 and ISO 5167-5:2015.
[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.
INTERNATIONAL STANDARD ISO 5167-6:2019(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 5167-6:2019(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 http: //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
q = εβDp2Δ ρ (1)
()
m 1
1−β
and
4A
t
β = (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.
...