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 5167-3:2003)

Migrated from Progress Sheet (TC Comment) (2000-07-10): WIs CSF05019 to CSF05022 revises EN ISO 5167-1:1995 (CC/000707)

Durchflussmessung von Fluiden mit Drosselgeräten in voll durchströmten Leitungen mit Kreisquerschnitt - Teil 3: Düsen und Venturidüsen (ISO 5167-3:2003)

Dieser Teil von ISO 5167 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 eingebaut sind, fest.
Dieser Teil von ISO 5167 enthält grundlegende Informationen für die Durchflussberechnung und ist gemeinsam mit den in ISO 5167-1 festgelegten Anforderungen anzuwenden.
Dieser Teil von ISO 5167 gilt nur 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 jedes Gerät nur innerhalb festgelegter Grenzen für Rohrdurchmesser, Rohrrauheit, Durchmesserverhältnis und Reynolds-Zahl verwendet werden. Dieser Teil von ISO 5167 gilt nicht für Messungen bei pulsierenden Strömungen, für Rohrdurchmesser kleiner als 50 mm oder größer als 630 mm und für Reynolds-Zahlen unter 10 000.
Dieser Teil von ISO 5167 behandelt
a) zwei Arten von Norm-Düsen:
1) die ISA-1932-Düse );
2) die Langradius-Düse );
b)   die Venturidüse.
Die zwei Arten von Norm-Düsen sind grundsätzlich verschieden und sind in diesem Teil von ISO 5167 getrennt behandelt. Die Venturidüse hat die gleiche Stirnseite auf der Einlaufseite wie die ISA-1932-Düse, aber einen divergierenden Abschnitt 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 beide Düsen und für die Venturidüse wurden direkte Kalibrierungen, ausreichend in Anzahl, Spreizung und Qualität, durchgeführt, sodass deren Ergebnisse und Koeffizienten auf ähnliche Anordnungen innerhalb bestimmter Grenzen der Messunsicherheit übertragbar sind.

Mesure de débit des fluides au moyen d'appareils déprimogenes insérés dans des conduites en charge de section circulaire - Partie 3: Tuyeres et Venturi-tuyeres (ISO 5167-3:2003)

L'ISO 5167-3:2003 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.
L'ISO 5167-3:2003 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.
L'ISO 5167-3:2003 est applicable uniquement aux tuyères et aux Venturi-tuyères utilisés dans les limites spécifiées de diamètre de conduite et de nombre de Reynolds, dans lesquels l'écoulement reste subsonique dans tout le tronçon de mesurage contenant un fluide pouvant être considéré comme monophasique. Elle n'est pas applicable au mesurage d'un écoulement pulsé. Elle 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.
L'ISO 5167-3:2003 traite de deux types de tuyères normalisées: de la tuyère ISA 1932 et de la tuyère à long rayon, ainsi que du Venturi-tuyère.
Les deux types de tuyères normalisées sont fondamentalement différents et sont décrits séparément dans l'ISO 5167-3:2003. 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 également décrit séparément. Ce modèle présente une perte de pression plus basse qu'une tuyère similaire. Pour les deux types de tuyères normalisées 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.

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 5167-3:2003)

General Information

Status
Withdrawn
Publication Date
31-Dec-2003
Withdrawal Date
01-Oct-2020
Technical Committee
Current Stage
9900 - Withdrawal (Adopted Project)
Start Date
02-Oct-2020
Due Date
25-Oct-2020
Completion Date
02-Oct-2020

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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-

3:2003)

Durchflussmessung von Fluiden mit Drosselgeräten in voll durchströmten Leitungen mit

Kreisquerschnitt - Teil 3: Düsen und Venturidüsen (ISO 5167-3:2003)
Mesure de débit des fluides au moyen d'appareils déprimogenes insérés dans des

conduites en charge de section circulaire - Partie 3: Tuyeres et Venturi-tuyeres (ISO

5167-3:2003)
Ta slovenski standard je istoveten z: EN ISO 5167-3:2003
ICS:
17.120.10 Pretok v zaprtih vodih Flow in closed conduits
SIST EN ISO 5167-3:2004 en

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

---------------------- Page: 1 ----------------------
SIST EN ISO 5167-3:2004
---------------------- Page: 2 ----------------------
SIST EN ISO 5167-3:2004
EUROPEAN STANDARD
EN ISO 5167-3
NORME EUROPÉENNE
EUROPÄISCHE NORM
March 2003
ICS 17.120.10 Together with EN ISO 5167-1:2003,
EN ISO 5167-2:2003 and EN ISO 5167-4:2003,
supersedes EN ISO 5167-1:1995
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 5167-3:2003)

Mesure de débit des fluides au moyen d'appareils Durchflussmessung von Fluiden mit Drosselgeräten in voll

déprimogènes insérés dans des conduites en charge de durchströmten Leitungen mit Kreisquerschnitt - Teil 3:

section circulaire - Partie 3: Tuyères et Venturi-tuyères Düsen und Venturidüsen (ISO 5167-3:2003)

(ISO 5167-3:2003)
This European Standard was approved by CEN on 20 February 2003.

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 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 Management Centre has the same status as the official

versions.

CEN members are the national standards bodies of Austria, Belgium, Czech Republic, Denmark, Finland, France, Germany, Greece,

Hungary, Iceland, Ireland, Italy, Luxembourg, Malta, Netherlands, Norway, Portugal, Slovakia, Spain, Sweden, Switzerland and United

Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION
EUROPÄISCHES KOMITEE FÜR NORMUNG
Management Centre: rue de Stassart, 36 B-1050 Brussels

© 2003 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 5167-3:2003 E

worldwide for CEN national Members.
---------------------- Page: 3 ----------------------
SIST EN ISO 5167-3:2004
EN ISO 5167-3:2003 (E)
CORRECTED 2003-09-03
Foreword

This document (EN ISO 5167-3:2003) has been prepared by Technical Committee ISO/TC 30

"Measurement of fluid flow in closed conduits" in collaboration with CMC.

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 September 2003, and conflicting national

standards shall be withdrawn at the latest by September 2003.

This document, together with EN ISO 5167-1:2003, EN ISO 5167-2:2003 and EN ISO 5167-4:2003,

supersedes EN ISO 5167-1:1995.

According to the CEN/CENELEC Internal Regulations, the national standards organizations of the

following countries are bound to implement this European Standard: Austria, Belgium, Czech

Republic, Denmark, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy,

Luxembourg, Malta, Netherlands, Norway, Portugal, Slovakia, Spain, Sweden, Switzerland and the

United Kingdom.
Endorsement notice

The text of ISO 5167-3:2003 has been approved by CEN as EN ISO 5167-3:2003 without any

modifications.

NOTE Normative references to International Standards are listed in Annex ZA (normative).

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SIST EN ISO 5167-3:2004
EN ISO 5167-3:2003 (E)
Annex ZA
(normative)
Normative references to international publications
with their relevant European publications

This European Standard incorporates by dated or undated reference, provisions from other

publications. These normative references are cited at the appropriate places in the text and the

publications are listed hereafter. For dated references, subsequent amendments to or revisions of any

of these publications apply to this European Standard only when incorporated in it by amendment or

revision. For undated references the latest edition of the publication referred to applies (including

amendments).

NOTE Where an International Publication has been modified by common modifications, indicated by

(mod.), the relevant EN/HD applies.
Publication Year Title EN Year
ISO 4006 1991 Measurement of fluid flow in closed EN 24006 1993
conduits - Vocabulary and symbols
ISO 5167-1 2003 Measurement of fluid flow by means of EN ISO 5167-1 2003
pressure differential devices inserted in
circular cross-section conduits running
full - Part 1: General principles and
requirements
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SIST EN ISO 5167-3:2004
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SIST EN ISO 5167-3:2004
INTERNATIONAL ISO
STANDARD 5167-3
First edition
2003-03-01
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 5167-3:2003(E)
ISO 2003
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SIST EN ISO 5167-3:2004
ISO 5167-3:2003(E)
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© ISO 2003

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ii © ISO 2003 — All rights reserved
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SIST EN ISO 5167-3:2004
ISO 5167-3:2003(E)
Contents Page

Foreword............................................................................................................................................................ iv

Introduction ........................................................................................................................................................ v

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

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

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

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

5.3 Venturi nozzles.................................................................................................................................... 13

6 Installation requirements ................................................................................................................... 18

6.1 General................................................................................................................................................. 18

6.2 Minimum upstream and downstream straight lengths for installation between various

fittings and the primary device.......................................................................................................... 18

6.3 Flow conditioners ............................................................................................................................... 23

6.4 Circularity and cylindricality of the pipe........................................................................................... 23

6.5 Location of primary device and carrier rings................................................................................... 24

6.6 Method of fixing and gaskets ............................................................................................................ 25

Annex A (informative) Tables of discharge coefficients and expansibility [expansion] factors.............. 26

Bibliography ..................................................................................................................................................... 30

© ISO 2003 — All rights reserved iii
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SIST EN ISO 5167-3:2004
ISO 5167-3:2003(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.

International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.

The main task of technical committees is to prepare International Standards. Draft International Standards

adopted by the technical committees are circulated to the member bodies for voting. Publication as an

International Standard requires approval by at least 75 % of the member bodies casting a vote.

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.

ISO 5167-2 was prepared by Technical Committee ISO/TC 30, Measurement of fluid flow in closed conduits,

Subcommittee SC 2, Pressure differential devices.

This first edition of ISO 5167-3, together with the second edition of ISO 5167-1 and the first editions of

ISO 5167-2 and ISO 5167-4, cancels and replaces the first edition of ISO 5167-1:1991, which has been

technically revised, and ISO 5167-1:1991/Amd.1:1998.

ISO 5167 consists of the following parts, under the general title Measurement of fluid flow by means of

pressure differential devices inserted in circular-cross section conduits running full :

 Part 1: General principles and requirements
 Part 2: Orifice plates
 Part 3: Nozzles and Venturi nozzles
 Part 4:Venturi tubes
iv © ISO 2003 — All rights reserved
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SIST EN ISO 5167-3:2004
ISO 5167-3:2003(E)
Introduction

ISO 5167, consisting of four parts, covers the geometry and method of use (installation and operating

conditions) of orifice plates, nozzles and Venturi tubes 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 four 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 and

ISO 5167-4.

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.
d) ISO 5167-4 specifies classical Venturi tubes .

Aspects of safety are not dealt with in Parts 1 to 4 of ISO 5167. It is the responsibility of the user to ensure

that the system meets applicable safety regulations.
___________________________

1) See ISO 2186:1973, Fluid flow in closed conduits — Connections for pressure signal transmissions between primary

and secondary elements.

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 2003 — All rights reserved v
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SIST EN ISO 5167-3:2004
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SIST EN ISO 5167-3:2004
INTERNATIONAL STANDARD ISO 5167-3:2003(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 part of ISO 5167 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 part of ISO 5167 also provides background information for calculating the flowrate and is applicable in

conjunction with the requirements given in ISO 5167-1.

This part of ISO 5167 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 part of ISO 5167 deals with
a) two types of standard nozzles:
1) the ISA 1932 nozzle;
2) the long radius nozzle ;
b) the Venturi nozzle.

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

ISO 5167. 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 both 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.
____________________________

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 2003 — All rights reserved 1
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SIST EN ISO 5167-3:2004
ISO 5167-3:2003(E)
2 Normative references

The following referenced documents are indispensable for the application 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 4006:1991, Measurement of fluid flow in closed conduits — Vocabulary and symbols

ISO 5167-1:2003, 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.

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 part of ISO 5167.
The mass flowrate can be determined by Equation (1):
C π
qd=∆ερ2p (1)
m 1
1− β

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

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.

Computation of the flowrate, which is a purely arithmetic process, is performed by replacing the different items

on the right-hand side of Equation (1) by their numerical values. Tables A.1 to A.4 are given for convenience.

Tables A.1 to A.3 give the values of C as a function of β. Table A.4 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 , which is itself dependent on q and has 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 Equation (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 2003 — All rights reserved
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SIST EN ISO 5167-3:2004
ISO 5167-3:2003(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, of 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; and

 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 = 2D/3, the radial width of this flat part is zero.

When d is greater than 2D/3, 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 is 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 < 2D/3 while its radius R is

equal to 0,2d ± 0,02d for β < 0,5 and to 0,2d ± 0,006d for β W 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 W 0,5. Its centre is at d/2 + d/3 = 5d/6 from

the axial centreline and at
12 + 39
ad== 0,304 1d
from the flat inlet part A.
© ISO 2003 — All rights reserved 3
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SIST EN ISO 5167-3:2004
ISO 5167-3:2003(E)
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.

4 © ISO 2003 — All rights reserved
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SIST EN ISO 5167-3:2004
ISO 5167-3:2003(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 the height (c −d)/2 of the recess to its axial length shall not be greater than 1,2.

The outlet edge G shall be sharp.

5.1.2.7 The total length of the nozzle, excluding the recess F, as a function of β is equal to

0,604 1d for 0,3uuβ
and
0,75 0,25 2
0,404 1+− − 0,522 5 d for < βu 0,8 .
β 3

5.1.2.8 The profile of the convergent inlet shall be checked by means of a template.

Two diameters of the convergent inlet in the same plane perpendicular to the axial centreline shall not differ

from each other by more than 0,1 % of their mean value.

5.1.2.9 The surface of the upstream face and the throat shall be polished such that they have a

roughness criterion Ra u 10 d.
5.1.3 Downstream face
5.1.3.1 The thickness H shall not exceed 0,1D.

5.1.3.2 Apart from the condition given in 5.1.3.1, the profile and the surface finish of the downstream face

are not specified (see 5.1.1).
5.1.4 Material and manufacture

The ISA 1932 nozzle may be manufactured from any material and in any way, provided that it remains in

accordance with the foregoing description during flow measurement.
5.1.5 Pressure tappings
5.1.5.1 Corner pressure tappings shall be used upstream of the nozzle.

The upstream pressure tappings may be either single tappings or annular slots. Both types of tappings may

be located either in the pipe or its flanges or in carrier rings as shown in Figure 1.

The spacing between the centrelines of individual upstream tappings and face A is equal to half the diameter

or to half the width of the tappings themselves, so that the tapping holes break through the wall flush with

face A. The centreline of individual upstream tappings shall meet the centreline of the primary device at an

angle of as near 90° as possible.

The diameter δ of a single upstream tapping and the width a of annular slots are specified below. The

minimum diameter is determined in practice by the need to prevent accidental blockage and to give

satisfactory dynamic performance.
For clean fluids and vapours:
 for β u 0,65: 0,005D u a or δ u 0,03D;
 for β > 0,65: 0,01D u a or δ u 0,02D.
© ISO 2003 — All rights reserved 5
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SIST EN ISO 5167-3:2004
ISO 5167-3:2003(E)
For any value of β:
 for clean fluids: 1 mm u a or δ u 10 mm;
 for vapours, in the case of annular chambers: 1 mm u a u 10 mm;

 for vapours and for liquefied gases, in the case of single tappings: 4 mm u δ u 10 mm.

The annular slots usually break through the pipe over the entire perimeter, with no break in continuity. If not,

each annular chamber shall connect with the inside of the pipe by at least four openings, the axes of which

are at equal angles to one another and the individual opening area of which is at least 12 mm .

The internal diameter b of the carrier rings shall be greater than or equal to the diameter D of the pipe, to

ensure that they do not protrude into the pipe, but shall be less than or equal to 1,04D. Moreover, the following

condition shall be met:
bD− c 0,1
××100u
0,1+ 2,3β
The length c of the upstream ring (see Figure 1) shall not be greater than 0,5D.

The thickness f of the slot shall be greater than or equal to twice the width a of the annular slot. The area of

the cross-section of the annular chamber, gh, shall be greater than or equal to half the total area of the

opening connecting this chamber to the inside of the pipe.

All surfaces of the ring which are in contact with the measured fluid shall be clean and shall have a well-

machined finish.

The pressure tappings connecting the annular chambers to the secondary devices are pipe-wall tappings,

circular at the point of break-through and with a diameter j between 4 mm and 10 mm.

The upstream and downstream carrier rings need not necessarily be symmetrical in relation to each other, but

they shall both conform to the preceding requirements.

The diameter of the pipe shall be measured as specified in 6.4.2, the carrier ring being regarded as part of the

primary device. This also applies to the distance requirement given in 6.4.4 so that s shall be measured from

the upstream edge of the recess formed by the carrier ring.

5.1.5.2 The downstream pressure tappings may either be corner tappings as described in 5.1.5.1 or be

as described in the remainder of this section.

The distance between the centre of the tapping and the upstream face of the nozzle shall be

 u 0,15D for β u 0,67
 u 0,20D for β > 0,67

When installing the pressure tappings, due account shall be taken of the thickness of the gaskets and/or

sealing material.

The centreline of the tapping shall meet the pipe centreline at an angle as near to 90° as possible but in every

case within 3° of the perpendicular. At the point of break-through, the hole shall be circular. The edges shall

be flush with the internal surface of the pipe wall and as sharp as possible. To ensure the elimination of all

burrs or wire edges at the inner edge, rounding is permitted but shall be kept as small as possible and, where

it can be measured, its radius shall be less than one-tenth of the pressure-tapping diameter. No irregularity

shall appear inside the connecting hole, on the edges of the hole drilled in the pipe wall or on t

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