oSIST prEN ISO 5167-3:2022

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/FDIS 5167-3:2022)

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[1] ISA is the abbreviation for the International Federation of the National Standardizing Associations, which was superseded by ISO in 1946.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/FDIS 5167-3:2022)

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/FDIS 5167-3:2022)

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/FDIS 5167-3:2022)

General Information

• Status: Not Published
• Public Enquiry End Date: 02-Oct-2022
• ICS: 17.120.10 - Flow in closed conduits
• Technical Committee: IMIN - Measurement instruments
• Current Stage: 4020 - Public enquire (PE) (Adopted Project)
• Start Date: 07-Jul-2022
• Due Date: 24-Nov-2022
• Ref Project: prEN ISO 5167-3 - 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/DIS 5167-3:2022)

RELATIONS

• Revised: SIST EN 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)
• Effective Date: 30-Mar-2022

Standards Content (sample)

SLOVENSKI STANDARD
oSIST prEN ISO 5167-3:2022
01-september-2022

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/FDIS 5167-3:2022)

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/FDIS 5167

-3:2022)

Durchflussmessung von Fluiden mit Drosselgeräten in voll durchströmten Leitungen mit

Kreisquerschnitt - Teil 3: Düsen und Venturidüsen (ISO/FDIS 5167-3:2022)
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/FDIS 5167-3:2022)
Ta slovenski standard je istoveten z: prEN ISO 5167-3
ICS:
17.120.10 Pretok v zaprtih vodih Flow in closed conduits
oSIST prEN ISO 5167-3:2022 en,fr,de

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

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oSIST prEN ISO 5167-3:2022
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oSIST prEN ISO 5167-3:2022
FINAL
INTERNATIONAL ISO/FDIS
DRAFT
STANDARD 5167-3
ISO/TC 30/SC 2
Measurement of fluid flow by means of
Secretariat: BSI
pressure differential devices inserted
Voting begins on:
2022-06-29 in circular cross-section conduits
running full —
Voting terminates on:
2022-09-21
Part 3:
Nozzles and Venturi nozzles
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/CEN PARALLEL PROCESSING
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 SUPPOR TING
DOCUMENTATION.
IN ADDITION TO THEIR EVALUATION AS
Reference number
BEING ACCEPTABLE FOR INDUSTRIAL, TECHNO-
ISO/FDIS 5167-3:2022(E)
LOGICAL, COMMERCIAL AND USER PURPOSES,
DRAFT INTERNATIONAL STANDARDS MAY ON
OCCASION HAVE TO BE CONSIDERED IN THE
LIGHT OF THEIR POTENTIAL TO BECOME STAN-
DARDS TO WHICH REFERENCE MAY BE MADE IN
NATIONAL REGULATIONS. © ISO 2022
---------------------- Page: 3 ----------------------
oSIST prEN ISO 5167-3:2022
ISO/FDIS 5167-3:2022(E)
FINAL
INTERNATIONAL ISO/FDIS
DRAFT
STANDARD 5167-3
ISO/TC 30/SC 2
Measurement of fluid flow by means of
Secretariat: BSI
pressure differential devices inserted
Voting begins on:
2022-06-16 in circular cross-section conduits
running full —
Voting terminates on:
2022-08-11
Part 3:
Nozzles and Venturi nozzles
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
COPYRIGHT PROTECTED DOCUMENT
© ISO 2022
ISO/CEN PARALLEL PROCESSING

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.
RECIPIENTS OF THIS DRAFT ARE INVITED TO
ISO copyright office
SUBMIT, WITH THEIR COMMENTS, NOTIFICATION
OF ANY RELEVANT PATENT RIGHTS OF WHICH
CP 401 • Ch. de Blandonnet 8
THEY ARE AWARE AND TO PROVIDE SUPPOR TING
CH-1214 Vernier, Geneva
DOCUMENTATION.
Phone: [phone]
IN ADDITION TO THEIR EVALUATION AS
Reference number
Email: [e-mail]
BEING ACCEPTABLE FOR INDUSTRIAL, TECHNO-
ISO/FDIS 5167-3:2022(E)
Website: www.iso.org
LOGICAL, COMMERCIAL AND USER PURPOSES,
DRAFT INTERNATIONAL STANDARDS MAY ON
Published in Switzerland
OCCASION HAVE TO BE CONSIDERED IN THE
LIGHT OF THEIR POTENTIAL TO BECOME STAN-
DARDS TO WHICH REFERENCE MAY BE MADE IN
© ISO 2022 – All rights reserved
NATIONAL REGULATIONS. © ISO 2022
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oSIST prEN ISO 5167-3:2022
ISO/FDIS 5167-3:2022(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 ....................................................................................................................................... 11

5.2.4 Material and manufacture ...................................................................................................................................... 11

5.2.5 Pressure tappings ........................................................................................................................................................... 11

5.2.6 Coefficients of long radius nozzles ..................................................................................................................12

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

5.2.8 Pressure loss, Δϖ ............................................................................................................................................................13

5.3 Throat-tapped nozzles .................................................................................................................................................................. 13

5.3.1 General .....................................................................................................................................................................................13

5.3.2 Profile of throat-tapped nozzle........................................................................................................................... 13

5.3.3 Material and manufacturing ................................................................................................................................. 14

5.3.4 Pressure tappings ........................................................................................................................................................... 15

5.3.5 Coefficients ........................................................................................................................................................................... 15

5.3.6 Uncertainties ...................................................................................................................................................................... 16

5.3.7 Calibration and extrapolation ............................................................................................................................. 16

5.3.8 Pressure Loss ..................................................................................................................................................................... 17

5.4 Venturi nozzles .................................................................................................................................................................................... 17

5.4.1 General shape ..................................................................................................................................................................... 17

5.4.2 Material and manufacture ...................................................................................................................................... 20

5.4.3 Pressure tappings ........................................................................................................................................................... 20

5.4.4 Coefficients ........................................................................................................................................................................... 21

5.4.5 Uncertainties ......................................................................................................................................................................22

5.4.6 Pressure loss .......................................................................................................................................................................22

6 Installation requirements ......................................................................................................................................................................23

6.1 General ........................................................................................................................................................................................................23

6.2 Minimum upstream and downstream straight lengths for installation between

various fittings and the primary device ....................................................................................................................... 23

6.3 Flow conditioners ............................................................................................................................................................................. 29

6.4 Circularity and cylindricality of the pipe ....................................................................................................................29

6.5 Location of primary device and carrier rings ..........................................................................................................30

6.6 Method of fixing and gaskets .................................................................................................................................................. 31

7 Flow calibration of nozzles ....................................................................................................................................................................31

7.1 General ........................................................................................................................................................................................................ 31

7.2 Test facility .............................................................................................................................................................................................. 32

iii
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oSIST prEN ISO 5167-3:2022
ISO/FDIS 5167-3:2022(E)

7.3 Meter installation ......... ..................................................................................................................................................................... 32

7.4 Design of the test programme ............................................................................................................................................... 32

7.5 Reporting the calibration results ....................................................................................................................................... 32

7.6 Uncertainty analysis of the calibration ......................................................................................................................... 32

7.6.1 General ..................................................................................................................................................................................... 32

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

7.6.3 Uncertainty of the nozzle ......................................................................................................................................... 33

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

factors ...........................................................................................................................................................................................................................34

Annex B (informative) Akashi type (Mitsubishi type) flow conditioner ...................................................................41

Bibliography .............................................................................................................................................................................................................................42

© ISO 2022 – All rights reserved
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oSIST prEN ISO 5167-3:2022
ISO/FDIS 5167-3:2022(E)
Foreword

ISO (the International Organization for Standardization) is a worldwide federation of national standards

bodies (ISO member bodies). The work of preparing International Standards is normally carried out

through ISO technical committees. Each member body interested in a subject for which a technical

committee has been established has the right to be represented on that committee. International

organizations, governmental and non-governmental, in liaison with ISO, also take part in the work.

ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of

electrotechnical standardization.

The procedures used to develop this document and those intended for its further maintenance are

described in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the

different types of ISO documents should be noted. This document was drafted in accordance with the

editorial rules of the ISO/IEC Directives, Part 2 (see www.iso.org/directives).

Attention is drawn to the possibility that some of the elements of this document may be the subject of

patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of

any patent rights identified during the development of the document will be in the Introduction and/or

on the ISO list of patent declarations received (see www.iso.org/patents).

Any trade name used in this document is information given for the convenience of users and does not

constitute an endorsement.

For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and

expressions related to conformity assessment, as well as information about ISO's adherence to

the World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT) see

www.iso.org/iso/foreword.html.

This document was prepared by Technical Committee ISO/TC 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 third edition cancels and replaces the second edition (ISO 5167-3:2020), of which it constitutes a

minor revision. The main changes are as follows:.
— harmonization with ISO/IEC Guide 98-3;
— minor changes to give harmonization with the other parts of ISO 5167.
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 2022 – All rights reserved
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oSIST prEN ISO 5167-3:2022
ISO/FDIS 5167-3:2022(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 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. ISO 5167 also

provides methdology for bespoke calibration of differential pressure meters.

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 (ISO 2186) and tertiary devices will be mentioned only occasionally.

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.
© ISO 2022 – All rights reserved
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oSIST prEN ISO 5167-3:2022
FINAL DRAFT INTERNATIONAL STANDARD ISO/FDIS 5167-3:2022(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.

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.

© ISO 2022 – All rights reserved
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oSIST prEN ISO 5167-3:2022
ISO/FDIS 5167-3:2022(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 https:// 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 5167-1:2022, Clause 8.

Similarly, the value of the volume flowrate can be calculated by Formula (2) 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 discharge coefficient C may be dependent on Re or Re which is itself dependent on q and has to

D d m

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.
© ISO 2022 – All rights reserved
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oSIST prEN ISO 5167-3:2022
ISO/FDIS 5167-3:2022(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 the

throat.
The letters in the following text refer to those shown on Figure 1.
5.1.2 Nozzle profile
5.1.2.1 The profile of the nozzle may be characterized by distinguishing:
— a flat inlet part A, perpendicular to the centreline;
— a convergent section defined by two arcs of circumference B and C;
— a cylindrical throat E;

— a recess F which is optional (it is required only if damage to the edge G is feared).

5.1.2.2 The flat inlet part A is limited by a circumference centred on the axis of revolution, with a

diameter of 1,5d, and by the inside circumference of the pipe, of diameter D.
When d = (2/3)D, the radial width of this flat part is zero.

When d is greater than (2/3)D, the upstream face of the nozzle does not include a flat inlet part within

the pipe. In this case, the nozzle is manufactured as if D were greater than 1,5d, and the inlet flat part

is then faced off so that the largest diameter of the convergent profile is just equal to D [see 5.1.2.7 and

Figure 1 b)].

5.1.2.3 The arc of circumference B is tangential to the flat inlet part A when d < (2/3)D while its

radius R is equal to 0,2d ± 0,02d for β < 0,5 and to 0,2d ± 0,006d for β ≥ 0,5. Its centre is at 0,2d from the

inlet plane and at 0,75d from the axial centreline.

5.1.2.4 The arc of circumference C is tangential to the arc of circumference B and to the throat E. Its

radius R is equal to d/3 ± 0,033d for β < 0,5 and to d/3 ± 0,01d for β ≥ 0,5. Its centre is at d/2 + d/3 = (5/6)

d from the axial centreline and as given by Formula (3), at
 
12+ 39
ad= =0,3041d (3)
 
 
from the flat inlet part A.
© ISO 2022 – All rights reserved
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oSIST prEN ISO 5167-3:2022
ISO/FDIS 5167-3:2022(E)
a) d ≤ (2/3)D b) d > (2/3)D
Key
1 portion to be cut off
See 5.1.2.7.
Direction of flow.
Figure 1 — ISA 1932 nozzle
5.1.2.5 The throat E has a diameter d and a length b = 0,3d.

The value d of the diameter of the throat shall be taken as the mean of the measurements of at least four

diameters distributed in axial planes and at approximately equal angles to each other.

The throat shall be cylindrical. No diameter of any cross-section shall differ by more than 0,05 % from

the value of the mean diameter. This requirement is considered to be satisfied when the deviations in

the length of any of the measured diameters comply with the said requirement in respect of deviation

from the mean.
© ISO 2022 – All rights reserved
---------------------- Page: 12 ----------------------
oSIST prEN ISO 5167-3:2022
ISO/FDIS 5167-3:2022(E)

5.1.2.6 The recess F has a diameter c equal to at least 1,06d and a length less than or equal to 0,03d.

The ratio of th
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