Measurement of fluid flow by means of pressure differential devices inserted in circular cross-section conduits running full - Part 3: Nozzles and Venturi nozzles (ISO 5167-3:2019)

This document specifies the geometry and method of use (installation and operating conditions) of nozzles and Venturi nozzles when they are inserted in a conduit running full to determine the flowrate of the fluid flowing in the conduit.
This document also provides background information for calculating the flowrate and is applicable in conjunction with the requirements given in ISO 5167‑1.
This document is applicable to nozzles and Venturi nozzles in which the flow remains subsonic throughout the measuring section and where the fluid can be considered as single-phase. In addition, each of the devices can only be used within specified limits of pipe size and Reynolds number. It is not applicable to the measurement of pulsating flow. It does not cover the use of nozzles and Venturi nozzles in pipe sizes less than 50 mm or more than 630 mm, or where the pipe Reynolds numbers are below 10 000.
This document deals with
a)   three types of standard nozzles:
     ISA 1932[1] nozzle;
     the long radius nozzle[2];
     the throat-tapped nozzle
b)   the Venturi nozzle.
The three types of standard nozzle are fundamentally different and are described separately in this document. The Venturi nozzle has the same upstream face as the ISA 1932 nozzle, but has a divergent section and, therefore, a different location for the downstream pressure tappings, and is described separately. This design has a lower pressure loss than a similar nozzle. For all of these nozzles and for the Venturi nozzle 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.
[1]   ISA is the abbreviation for the International Federation of the National Standardizing Associations, which was superseded by ISO in 1946.
[2]   The long radius nozzle differs from the ISA 1932 nozzle in shape and in the position of the pressure tappings.

Durchflussmessung von Fluiden mit Drosselgeräten in voll durchströmten Leitungen mit Kreisquerschnitt - Teil 3: Düsen und Venturidüsen (ISO 5167-3:2020)

Dieses Dokument legt die geometrischen Formen und Maße sowie die Anwendung (Einbau- und Betriebsbedingungen) von Düsen und Venturidüsen, die in einer voll durchströmten Rohrleitung zur Bestimmung des Durchflusses eines Fluids eingebaut sind, fest.
Dieses Dokument enthält grundlegende Informationen für die Durchflussberechnung und ist gemeinsam mit den in ISO 5167-1 festgelegten Anforderungen anzuwenden.
Dieses Dokument ist anzuwenden für Düsen und Venturidüsen, in denen die Strömung im gesamten Messquerschnitt im Unterschallbereich liegt und wo das Fluid als einphasig betrachtet werden kann. Weiterhin kann das betreffende Gerät nur innerhalb festgelegter Grenzen für Rohrdurchmesser und Reynolds-Zahl verwendet werden. Dieses Dokument ist nicht anzuwenden für Messungen bei pulsierenden Strömungen sowie für die Verwendung von Düsen und Venturidüsen bei Rohrdurchmessern kleiner als 50 mm oder größer als 630 mm oder für auf das Rohr bezogene Reynolds-Zahlen unter 10 000.
Dieses Dokument behandelt
a) drei Arten von Norm-Düsen:
1) ISA 1932 Düsen ;
2) die Langradius-Düse ;
3) Düse mit Entnahmebohrung am Halsteil;
b) die Venturidüse.
Die drei Arten von Norm-Düsen sind grundsätzlich verschieden und sind in diesem Dokument getrennt behandelt. Die Venturidüse hat die gleiche Stirnseite auf der Einlaufseite wie die ISA 1932 Düse, aber ein divergierendes Teil (Diffusor) und deswegen eine andere Anordnung der Druckentnahmen auf der Auslaufseite und wird deshalb getrennt beschrieben. Diese Ausführung hat einen geringeren Druckverlust als eine gleichartige Düse. Für alle Düsen und für die Venturidüse wurden direkte Kalibrierungen, ausreichend in Anzahl, Spreizung und Qualität, durchgeführt, sodass die Ergebnisse der Kalibrierungen auf ähnliche Anordnungen übertragbar sind und die Kalibrierkoeffizienten innerhalb bestimmter Grenzen der Messunsicherheit angegeben werden können.

Mesurage du débit des fluides au moyen d'appareils déprimogènes insérés dans des conduites en charge de section circulaire - Partie 3: Tuyères et Venturi-tuyères (ISO 5167-3:2020)

Le présent document spécifie la géométrie et le mode d'emploi (conditions d'installation et d'utilisation) de tuyères et de Venturi-tuyères insérés dans une conduite en charge dans le but de déterminer le débit du fluide s'écoulant dans cette conduite.
Le présent document fournit également des informations de fond nécessaires au calcul de ce débit, et il convient de l'utiliser conjointement avec les exigences stipulées dans l'ISO 5167-1.
Le présent document est applicable aux tuyères et aux Venturi-tuyères dans lesquels l'écoulement reste subsonique dans tout le tronçon de mesurage et dans lesquels un fluide peut être considéré comme monophasique. De plus, chacun de ces appareils ne peut être utilisé que dans des limites spécifiées de diamètre de conduite et de nombre de Reynolds. Il n'est pas applicable au mesurage d'un écoulement pulsé. Il ne couvre pas l'utilisation de tuyères et de Venturi-tuyères dans des conduites de diamètre inférieur à 50 mm ou supérieur à 630 mm, ni les cas où les nombres de Reynolds rapportés à la tuyauterie sont inférieurs à 10 000.
Le présent document traite
a)    de trois types de tuyères normalisées:
     la tuyère ISA 1932[1];
     la tuyère à long rayon[2];
     la tuyère avec prises de pression au col;
b)    du Venturi-tuyère.
Les trois types de tuyères normalisées sont fondamentalement différents et sont décrits séparément dans le présent document. Le Venturi-tuyère a la même face amont que la tuyère ISA 1932, mais, étant donné qu'il comporte un divergent et, par conséquent, un emplacement différent pour les prises de pression aval, il est décrit séparément. Ce modèle présente une perte de pression plus basse qu'une tuyère similaire. Pour toutes ces tuyères et pour le Venturi-tuyère, des étalonnages directs ont été réalisés, en nombre suffisant, sur une gamme suffisante et avec une qualité suffisante pour permettre à des systèmes d'application cohérents de se baser sur leurs résultats et coefficients dans certaines limites prévisibles d'incertitude.
[1]   ISA est le sigle de la Fédération internationale des associations nationales de normalisation, organisme remplacé par l'ISO en 1946.
[2]   La tuyère à long rayon se distingue de la tuyère ISA 1932 par sa forme et par la position des prises de pression.

Merjenje pretoka fluida na osnovi tlačne razlike, povzročene z napravo, vstavljeno v polno zapolnjen vod s krožnim prerezom - 3. del: Šobe in Venturijeve šobe (ISO 5167-3:2020)

General Information

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Current Stage
6060 - Definitive text made available (DAV) - Publishing
Due Date
09-Sep-2020
Completion Date
09-Sep-2020

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SLOVENSKI STANDARD
SIST EN ISO 5167-3:2020
01-november-2020
Nadomešča:
SIST EN ISO 5167-3:2004

Merjenje pretoka fluida na osnovi tlačne razlike, povzročene z napravo, vstavljeno

v polno zapolnjen vod s krožnim prerezom - 3. del: Šobe in Venturijeve šobe (ISO
5167-3:2020)

Measurement of fluid flow by means of pressure differential devices inserted in circular

cross-section conduits running full - Part 3: Nozzles and Venturi nozzles (ISO 5167-

3:2019)

Durchflussmessung von Fluiden mit Drosselgeräten in voll durchströmten Leitungen mit

Kreisquerschnitt - Teil 3: Düsen und Venturidüsen (ISO 5167-3:2020)
Mesurage du débit des fluides au moyen d'appareils déprimogènes insérés dans des

conduites en charge de section circulaire - Partie 3: Tuyères et Venturi-tuyères (ISO

5167-3:2020)
Ta slovenski standard je istoveten z: EN ISO 5167-3:2020
ICS:
17.120.10 Pretok v zaprtih vodih Flow in closed conduits
SIST EN ISO 5167-3:2020 en,fr,de

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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SIST EN ISO 5167-3:2020
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SIST EN ISO 5167-3:2020
EN ISO 5167-3
EUROPEAN STANDARD
NORME EUROPÉENNE
September 2020
EUROPÄISCHE NORM
ICS 17.120.10 Supersedes EN ISO 5167-3:2003
English Version
Measurement of fluid flow by means of pressure
differential devices inserted in circular cross-section
conduits running full - Part 3: Nozzles and Venturi nozzles
(ISO 5167-3:2019)

Mesurage du 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 3: Tuyères et Venturi-tuyères Teil 3: Düsen und Venturidüsen (ISO 5167-3:2020)

(ISO 5167-3:2020)
This European Standard was approved by CEN on 24 February 2020.

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

© 2020 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 5167-3:2020 E

worldwide for CEN national Members.
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SIST EN ISO 5167-3:2020
EN ISO 5167-3:2020 (E)
Contents Page

European foreword ....................................................................................................................................................... 3

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SIST EN ISO 5167-3:2020
EN ISO 5167-3:2020 (E)
European foreword

This document (EN ISO 5167-3:2020) has been prepared by Technical Committee ISO/TC 30

"Measurement of fluid flow in closed conduits" in collaboration with Technical Committee CEN/SS F05

“Measuring Instruments” the secretariat of which is held 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 March 2021, and conflicting national standards shall

be withdrawn at the latest by March 2021.

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 5167-3:2003.

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 5167-3:2020 has been approved by CEN as EN ISO 5167-3:2020 without any

modification.
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SIST EN ISO 5167-3:2020
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SIST EN ISO 5167-3:2020
INTERNATIONAL ISO
STANDARD 5167-3
Second edition
2020-08
Measurement of fluid flow by means of
pressure differential devices inserted
in circular cross-section conduits
running full —
Part 3:
Nozzles and Venturi nozzles
Mesure de débit des fluides au moyen d'appareils déprimogènes
insérés dans des conduites en charge de section circulaire —
Partie 3: Tuyères et Venturi-tuyères
Reference number
ISO 5167-3:2020(E)
ISO 2020
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SIST EN ISO 5167-3:2020
ISO 5167-3:2020(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2020

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: +41 22 749 01 11
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii © ISO 2020 – All rights reserved
---------------------- Page: 8 ----------------------
SIST EN ISO 5167-3:2020
ISO 5167-3:2020(E)
Contents Page

Foreword ..........................................................................................................................................................................................................................................v

Introduction ................................................................................................................................................................................................................................vi

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

2 Normative references ...................................................................................................................................................................................... 1

3 Terms and definitions ..................................................................................................................................................................................... 2

4 Principles of the method of measurement and computation ................................................................................ 2

5 Nozzles and Venturi nozzles ..................................................................................................................................................................... 3

5.1 ISA 1932 nozzle ...................................................................................................................................................................................... 3

5.1.1 General shape ..................................................................................................................................................................... 3

5.1.2 Nozzle profile ...................................................................................................................................................................... 3

5.1.3 Downstream face ............................................................................................................................................................. 5

5.1.4 Material and manufacture ....................................................................................................................................... 5

5.1.5 Pressure tappings ........................................................................................................................................................... 5

5.1.6 Coefficients of ISA 1932 nozzles ........................................................................................................................ 7

5.1.7 Uncertainties ....................................................................................................................................................................... 8

5.1.8 Pressure loss, Δϖ ............................................................................................................................................................ 8

5.2 Long radius nozzles ............................................................................................................................................................................ 9

5.2.1 General...................................................................................................................................................................................... 9

5.2.2 Profile of high-ratio nozzle ...................................................................................................................................... 9

5.2.3 Profile of low-ratio nozzle .....................................................................................................................................12

5.2.4 Material and manufacture ....................................................................................................................................12

5.2.5 Pressure tappings ........................................................................................................................................................12

5.2.6 Coefficients of long radius nozzles ................................................................................................................13

5.2.7 Uncertainties ....................................................................................................................................................................13

5.2.8 Pressure loss, Δϖ .........................................................................................................................................................14

5.3 Throat-tapped nozzles ..................................................................................................................................................................14

5.3.1 General...................................................................................................................................................................................14

5.3.2 Profile of throat-tapped nozzle ........................................................................................................................14

5.3.3 Material and manufacturing ...............................................................................................................................15

5.3.4 Pressure Tappings .......................................................................................................................................................15

5.3.5 Coefficients ........................................................................................................................................................................16

5.3.6 Uncertainties ....................................................................................................................................................................17

5.3.7 Calibration and extrapolation ............................................................................................................................17

5.3.8 Pressure Loss ...................................................................................................................................................................18

5.4 Venturi nozzles.....................................................................................................................................................................................18

5.4.1 General shape ..................................................................................................................................................................18

5.4.2 Material and manufacture ....................................................................................................................................21

5.4.3 Pressure tappings ........................................................................................................................................................21

5.4.4 Coefficients ........................................................................................................................................................................22

5.4.5 Uncertainties ....................................................................................................................................................................23

5.4.6 Pressure loss .....................................................................................................................................................................23

6 Installation requirements........................................................................................................................................................................24

6.1 General ........................................................................................................................................................................................................24

6.2 Minimum upstream and downstream straight lengths for installation between

various fittings and the primary device .........................................................................................................................24

6.3 Flow conditioners ..............................................................................................................................................................................30

6.4 Circularity and cylindricality of the pipe .......................................................................................................................30

6.5 Location of primary device and carrier rings ............................................................................................................31

6.6 Method of fixing and gaskets ...................................................................................................................................................32

7 Flow calibration of nozzles .....................................................................................................................................................................32

7.1 General ........................................................................................................................................................................................................32

7.2 Test facility ...............................................................................................................................................................................................33

© ISO 2020 – All rights reserved iii
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SIST EN ISO 5167-3:2020
ISO 5167-3:2020(E)

7.3 Meter installation...............................................................................................................................................................................33

7.4 Design of the test programme .................................................................................................................................................33

7.5 Reporting the calibration results .........................................................................................................................................33

7.6 Uncertainty analysis of the calibration ...........................................................................................................................33

7.6.1 General...................................................................................................................................................................................33

7.6.2 Uncertainty of the test facility ...........................................................................................................................33

7.6.3 Uncertainty of the nozzle.......................................................................................................................................34

Annex A (informative) Tables of discharge coefficients and expansibility [expansion] factors ..........35

Annex B (informative) Akashi type (Mitsubishi type) flow conditioner ......................................................................42

Bibliography .............................................................................................................................................................................................................................43

iv © ISO 2020 – All rights reserved
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SIST EN ISO 5167-3:2020
ISO 5167-3:2020(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

w w w . is o . or g / is o/ f or ewor d . ht m l .

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 5167-3:2003), which has been technically

revised. The main changes compared to the previous edition are as follows:
— Addition of Subclause 5.3.
A list of all parts in the ISO 5167 series can be found on the ISO website.

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.
© ISO 2020 – All rights reserved v
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SIST EN ISO 5167-3:2020
ISO 5167-3:2020(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 meters and wedge meters when they are

inserted in a conduit running full to determine the flowrate of the fluid flowing in the conduit. It also

gives necessary information for calculating the flowrate 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

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 (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.

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 (all parts) covers primary devices; secondary devices will be

mentioned only occasionally.
ISO 5167 consists of 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 ISO 5167-2,

ISO 5167-3, ISO 5167-4, ISO 5167-5 and ISO 5167-6.

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, throat-tapped nozzles and Venturi

nozzles, which differ in shape and in the position of the pressure tappings.
d) ISO 5167-4 specifies classical Venturi tubes .
e) ISO 5167-5 specifies cone meters.
f) ISO 5167-6 specifies wedge meters.

Aspects of safety are not dealt within ISO 5167-1 to ISO 5167-6. It is the responsibility of the user to

ensure that the system meets applicable safety regulations.
1) See ISO 2186:2007.

2) Orifice plates with “vena contracta” pressure tappings are not considered in ISO 5167-2.

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.

vi © ISO 2020 – All rights reserved
---------------------- Page: 12 ----------------------
SIST EN ISO 5167-3:2020
INTERNATIONAL STANDARD ISO 5167-3:2020(E)
Measurement of fluid flow by means of pressure
differential devices inserted in circular cross-section
conduits running full —
Part 3:
Nozzles and Venturi nozzles
1 Scope

This document specifies the geometry and method of use (installation and operating conditions) of

nozzles and Venturi nozzles when they are inserted in a conduit running full to determine the flowrate

of the fluid flowing in the conduit.

This document also provides background information for calculating the flowrate and is applicable in

conjunction with the requirements given in ISO 5167-1.

This document is applicable to nozzles and Venturi nozzles in which the flow remains subsonic

throughout the measuring section and where the fluid can be considered as single-phase. In addition,

each of the devices can only be used within specified limits of pipe size and Reynolds number. It is

not applicable to the measurement of pulsating flow. It does not cover the use of nozzles and Venturi

nozzles in pipe sizes less than 50 mm or more than 630 mm, or where the pipe Reynolds numbers are

below 10 000.
This document deals with
a) three types of standard nozzles:
1) ISA 1932 nozzle;
2) the long radius nozzle ;
3) the throat-tapped nozzle
b) the Venturi nozzle.

The three types of standard nozzle are fundamentally different and are described separately in this

document. The Venturi nozzle has the same upstream face as the ISA 1932 nozzle, but has a divergent

section and, therefore, a different location for the downstream pressure tappings, and is described

separately. This design has a lower pressure loss than a similar nozzle. For all of these nozzles and for

the Venturi nozzle 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.
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.

5) ISA is the abbreviation for the International Federation of the National Standardizing Associations, which was

superseded by ISO in 1946.

6) The long radius nozzle differs from the ISA 1932 nozzle in shape and in the position of the pressure tappings.

© ISO 2020 – All rights reserved 1
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SIST EN ISO 5167-3:2020
ISO 5167-3:2020(E)
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 and ISO 5167-1 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/
4 Principles of the method of measurement and computation

The principle of the method of measurement is based on the installation of a nozzle or a Venturi nozzle

into a pipeline in which a fluid is running full. The installation of the primary device causes a static

pressure difference between the upstream side and the throat. The flowrate can be determined from

the measured value of this pressure difference and from the knowledge of the characteristics of the

flowing fluid as well as the circumstances under which the device is being used. It is assumed that the

device is geometrically similar to one on which calibration has been carried out and that the conditions

of use are the same, i.e. that it is in accordance with this document.
The mass flowrate can be determined by Formula (1):
C π
q = ερdp2Δ (1)
m 1
4 4
1−β

The uncertainty limits can be calculated using the procedure given in ISO 5167-1:2003, Clause 8.

Similarly, the value of the volume flowrate can be calculated since
q = (2)
where

ρ is the fluid density at the temperature and pressure for which the volume is stated;

q is the volume flowrate.

Computation of the flowrate, 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. Tables A.1 to A.5 are

given for convenience. Tables A.1, A.2 and A.4 give the values of C as a function of β. Table A.3 gives

the values of C as a function of Re . Table A.5 gives expansibility (expansion) factors ε. They are not

intended for precise interpolation. Extrapolation is not permitted.

The coefficient of discharge C may be dependent on Re or Re which is itself dependent on q and has

D d m

to be obtained by iteration. (See ISO 5167-1 for guidance regarding the choice of the iteration procedure

and initial estimates.)

The diameters d and D mentioned in Formula (1) are the values of the diameters 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.
2 © ISO 2020 – All rights reserved
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SIST EN ISO 5167-3:2020
ISO 5167-3:2020(E)

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 Nozzles and Venturi nozzles
5.1 ISA 1932 nozzle
5.1.1 General shape

The part of the nozzle inside the pipe is circular. The nozzle consists of a convergent section with a

rounded profile, and a cylindrical throat.

Figure 1 shows the cross-section of an ISA 1932 nozzle at a plane passing through the centreline of

...

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