FprEN ISO 5167-5

Measurement of fluid flow by means of pressure differential devices inserted in circular cross-section conduits running full - Part 5: Cone meters (ISO/FDIS 5167-5:2022)

This document specifies the geometry and method of use (installation and operating conditions) of cone meters when they are inserted in a conduit running full to determine the flow rate of the fluid flowing in the conduit.
As the uncertainty of an uncalibrated cone meter might be too high for a particular application, it might be deemed essential to calibrate the flow meter in accordance with Clause 7.
This document also provides background information for calculating the flow rate and is applicable in conjunction with the requirements given in ISO 5167‑1.
This document is applicable only to cone meters in which the flow remains subsonic throughout the measuring section and where the fluid can be considered as single-phase. Uncalibrated cone meters can only be used within specified limits of pipe size, roughness, β, and Reynolds number, Re. This document is not applicable to the measurement of pulsating flow. It does not cover the use of uncalibrated cone meters in pipes sized less than 50 mm or more than 500 mm, or where the pipe Reynolds numbers are below 8 × 104 or greater than 1,2 × 107.
A cone meter is a primary device which consists of a cone-shaped restriction held concentrically in the centre of the pipe with the nose of the cone upstream. The design of cone meter defined in this document has one or more upstream pressure tappings in the wall, and a downstream pressure tapping positioned in the back face of the cone with the connection to a differential pressure transmitter being a hole through the cone to the support bar, and then up through the support bar.
Alternative designs of cone meters are available; however, at the time of writing, there is insufficient data to fully characterize these devices, and therefore, these meters shall be calibrated in accordance with Clause 7.

Durchflussmessung von Fluiden mit Drosselgeräten in voll durchströmten Leitungen mit Kreisquerschnitt - Teil 5: Konus-Durchflussmesser (ISO/FDIS 5167-5:2022)

Dieses Dokument legt die Geometrie und Anwendungsverfahren (Einbau- und Betriebsbedingungen) von in voll durchströmten Leitungen eingesetzten Konus-Durchflussmessern fest, um die Durchflussrate des in den Leitungen hindurchfließenden Fluids zu bestimmen.
Da die Messunsicherheit eines unkalibrierten Konus-Durchflussmessers für eine bestimmte Anwendung zu groß sein könnte, könnte es erforderlich sein, den Durchflussmesser nach Abschnitt 7 zu kalibrieren.
Dieses Dokument gibt auch Hintergrundinformationen für die Berechnung der Durchflussrate und gilt in Verbindung mit den in ISO 5167 1 festgelegten Anforderungen.
Dieses Dokument ist nur auf Konus-Durchflussmesser anwendbar, in denen der Durchfluss über den gesamten Messbereich im Unterschallbereich bleibt und in dem das Fluid als einphasig bezeichnet werden kann. Unkalibrierte Konus-Durchflussmesser können nur innerhalb festgelegter Grenzen von Rohrgröße, Rauheit, β und Reynolds-Zahl angewendet werden. Dieses Dokument ist nicht für die Messung von pulsierendem Durchfluss anwendbar. Er behandelt nicht die Anwendung von unkalibrierten Durchflussmessern bei Rohrdurchmessern unter 50 mm oder über 500 mm, oder wenn die Rohr-Reynolds-Zahlen unter 8 × 104 liegen oder über 1,2 × 107.
Ein Konus-Durchflussmesser ist ein Primärgerät, das aus einer konusförmigen Verengung besteht, die konzentrisch in der Mitte des Rohres mit der Konusspitze gegen die Durchflussrichtung gehalten wird. Die konstruktive Ausführung des in diesem Dokument festgelegten Konus-Durchflussmessers hat eine oder mehrere einlaufseitig in der Wandung gelegene Druckentnahmen und eine auslaufseitig auf der Rückseite des Konus gelegene Druckentnahme(stelle) mit einer Verbindung über eine Bohrung durch den Konus zur Haltevorrichtung und dann durch die Haltevorrichtung nach oben zu einem Differenzdruckmessumformer.
Es stehen alternative Ausführungen von Konus-Durchflussmessern zur Verfügung; zum Zeitpunkt der Erstellung der Norm gibt es jedoch nicht genügend Daten, um diese Durchflussmesser vollständig zu beschreiben, und deshalb müssen diese Durchflussmesser nach Abschnitt 7 kalibriert werden.

Mesurage de débit des fluides au moyen d'appareils déprimogènes insérés dans des conduites en charge de section circulaire - Partie 5: Cônes de mesure (ISO/FDIS 5167-5:2022)

Le présent document spécifie la géométrie et le mode d’emploi (conditions d’installation et d’utilisation) de cônes de mesure insérés dans une conduite en charge dans le but de déterminer le débit du fluide s’écoulant dans cette conduite.
Étant donné que l’incertitude d’un cône de mesure non étalonné risque d’être trop élevée pour une application particulière, l’étalonnage du débitmètre conformément à l’Article 7 peut être considéré comme essentiel.
Le présent document fournit également des informations de fond nécessaires au calcul du débit et il est applicable conjointement avec les exigences stipulées dans l’ISO 5167‑1.
Le présent document est applicable uniquement aux cônes de mesure pour lesquels l’écoulement reste subsonique dans tout le tronçon de mesurage et où le fluide peut être considéré comme monophasique. Les cônes de mesure non étalonnés ne peuvent être utilisés que dans des limites spécifiées de diamètre de conduite, de rugosité, de valeur de β et de nombre de Reynolds, Re. Le présent document n’est pas applicable au mesurage d’un écoulement pulsé. Elle ne couvre pas l’utilisation de cônes de mesure non étalonnés dans des conduites de diamètre inférieur à 50 mm ou supérieur à 500 mm, ni les cas où les nombres de Reynolds associés à la tuyauterie sont inférieurs à 8 × 104 ou supérieurs à 1,2 × 107.
Un cône de mesure est un élément primaire composé d’une restriction conique maintenue de manière concentrique au centre de la conduite, le nez du cône étant situé en amont. La conception d’un cône de mesure définie dans le présent document comprend une ou plusieurs prises de pression amont dans la paroi et une prise de pression aval positionnée dans la face arrière du cône. Le raccordement à un transmetteur de pression différentielle se fait par un trou dans le cône menant à la barre de support, puis vers le haut à travers la barre de support.
D’autres conceptions de cônes de mesure sont possibles; cependant, au moment de la rédaction de cette norme, les données permettant de caractériser complètement ces appareils étaient insuffisantes et ces derniers doivent donc être étalonnés conformément à l’Article 7.

Merjenje pretoka fluida na osnovi tlačne razlike, povzročene z napravo, vstavljeno v polno zapolnjen vod s krožnim prerezom - 5. del: Stožčasta merila (ISO/FDIS 5167-5:2022)

General Information

• Status: Not Published
• ICS: 17.120.10 - Flow in closed conduits
• Technical Committee: CEN/SS F05 - Measuring insreuments
• Ref Project: kSIST FprEN ISO 5167-5:2022 - Measurement of fluid flow by means of pressure differential devices inserted in circular cross-section conduits running full - Part 5: Cone meters (ISO/FDIS 5167-5:2022)

RELATIONS

• Revised: EN ISO 5167-5:2016 - Measurement of fluid flow by means of pressure differential devices inserted in circular cross-section conduits running full - Part 5: Cone meters (ISO 5167-5:2016)
• Effective Date: 15-Sep-2021

Standards Content (sample)

SLOVENSKI STANDARD
oSIST prEN ISO 5167-5:2022
01-marec-2022

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

v polno zapolnjen vod s krožnim prerezom - 5. del: Stožčasta merila (ISO/DIS 5167-

5:2021)

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

cross-section conduits running full - Part 5: Cone meters (ISO/DIS 5167-5:2021)

Durchflussmessung von Fluiden mit Drosselgeräten in voll durchströmten Leitungen mit

Kreisquerschnitt - Teil 5: Konus-Durchflussmesser (ISO/DIS 5167-5:2021)
Mesure de débit des fluides au moyen d'appareils déprimogènes insérés dans des

conduites en charge de section circulaire - Partie 5: Cônes de mesure (ISO/DIS 5167-

5:2021)
Ta slovenski standard je istoveten z: prEN ISO 5167-5
ICS:
17.120.10 Pretok v zaprtih vodih Flow in closed conduits
oSIST prEN ISO 5167-5:2022 en,fr,de

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

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oSIST prEN ISO 5167-5:2022
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oSIST prEN ISO 5167-5:2022
DRAFT INTERNATIONAL STANDARD
ISO/DIS 5167-5
ISO/TC 30/SC 2 Secretariat: BSI
Voting begins on: Voting terminates on:
2021-12-13 2022-03-07
Measurement of fluid flow by means of pressure
differential devices inserted in circular cross-section
conduits running full —
Part 5:
Cone meters

Mesure de débit des fluides au moyen d'appareils déprimogènes insérés dans des conduites en charge de

section circulaire —
Partie 5: Cônes de mesure
ICS: 17.120.10
This document is circulated as received from the committee secretariat.
THIS DOCUMENT IS A DRAFT CIRCULATED
FOR COMMENT AND APPROVAL. IT IS
ISO/CEN PARALLEL PROCESSING
THEREFORE SUBJECT TO CHANGE AND MAY
NOT BE REFERRED TO AS AN INTERNATIONAL
STANDARD UNTIL PUBLISHED AS SUCH.
IN ADDITION TO THEIR EVALUATION AS
BEING ACCEPTABLE FOR INDUSTRIAL,
TECHNOLOGICAL, COMMERCIAL AND
USER PURPOSES, DRAFT INTERNATIONAL
STANDARDS MAY ON OCCASION HAVE TO
BE CONSIDERED IN THE LIGHT OF THEIR
POTENTIAL TO BECOME STANDARDS TO
WHICH REFERENCE MAY BE MADE IN
Reference number
NATIONAL REGULATIONS.
ISO/DIS 5167-5:2021(E)
RECIPIENTS OF THIS DRAFT ARE INVITED
TO SUBMIT, WITH THEIR COMMENTS,
NOTIFICATION OF ANY RELEVANT PATENT
RIGHTS OF WHICH THEY ARE AWARE AND TO
PROVIDE SUPPORTING DOCUMENTATION. © ISO 2021
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oSIST prEN ISO 5167-5:2022
ISO/DIS 5167-5:2021(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2021

All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may

be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on

the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address below

or ISO’s member body in the country of the requester.
ISO copyright office
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Phone: [phone]
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Website: www.iso.org
Published in Switzerland
© ISO 2021 – All rights reserved
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Contents Page

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

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

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

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

3 Terms and definitions .................................................................................................................................................................................... 1

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

5 Cone meters ............................................................................................................................................................................................................... 3

5.1 Field of application .............................................................................................................................................................................. 3

5.2 General shape .......................................................................................................................................................................................... 3

5.3 Material and manufacture ........................................................................................................................................................... 7

5.4 Pressure tappings ................................................................................................................................................................................ 7

5.5 Discharge coefficient, C ................................................................................................................................................................... 7

5.5.1 Limits of use ........................................................................................................................................................................... 7

5.5.2 Discharge coefficient of the cone meter ........................................................................................................ 8

5.6 Expansibility (expansion) factor, ε ....................................................................................................................................... 8

5.7 Uncertainty of the discharge coefficient, C ................................................................................................................... 8

5.8 Uncertainty of the expansibility (expansion) factor, ε ........................................................................................ 8

5.9 Pressure loss ............................................................................................................................................................................................ 9

6 Installation requirements .........................................................................................................................................................................9

6.1 General ........................................................................................................................................................................................................... 9

6.2 Minimum upstream and downstream straight lengths for installations between

various fittings and the cone meter .................................................................................................................................. 10

6.2.1 General ..................................................................................................................................................................................... 10

6.2.2 Single 90° bend ................................................................................................................................................................. 10

6.2.3 Two 90° bends in perpendicular planes ..................................................................................................... 10

6.2.4 Concentric expander .................................................................................................................................................... 10

6.2.5 Partially closed valves ................................................................................................................................................ 10

6.3 Additional specific installation requirements for cone meters ............................................................... 10

6.3.1 Circularity and cylindricality of the pipe .................................................................................................. 10

6.3.2 Roughness of the upstream and downstream pipe.......................................................................... 11

6.3.3 Positioning of a thermowell ................................................................................................................................... 11

7 Flow calibration of cone meters .......................................................................................................................................................11

7.1 General ........................................................................................................................................................................................................ 11

7.2 Test facility .............................................................................................................................................................................................. 11

7.3 Meter installation ......... ..................................................................................................................................................................... 12

7.4 Design of the test programme ...............................................................................................................................................12

7.5 Reporting the calibration results .......................................................................................................................................12

7.6 Uncertainty analysis of the calibration .........................................................................................................................12

7.6.1 General .....................................................................................................................................................................................12

7.6.2 Uncertainty of the test facility ............................................................................................................................12

7.6.3 Uncertainty of the discharge coefficient of the cone meter ......................................................12

Annex A (informative) Table of expansibility (expansion) factor .....................................................................................13

Bibliography .............................................................................................................................................................................................................................14

iii
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Foreword

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

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

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

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

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

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

electrotechnical standardization.

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

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

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

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

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

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

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

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

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

constitute an endorsement.

For an explanation on the meaning of ISO specific terms and expressions related to conformity

assessment, as well as information about ISO's adherence to the WTO principles in the Technical

Barriers to Trade (TBT) see the following URL: Foreword - Supplementary information

The committee responsible for this document is ISO/TC 30, Measurement of fluid flow in closed conduits,

Subcommittee SC 2, Pressure differential devices.

This second edition of ISO 5167-5 cancels and replaces the first edition (ISO 5167-5:2016), which has

been technically revised.

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
— Part 5: Cone meters
— Part 6: Wedge meters
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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 flow rate of the fluid in the conduit. It also gives

necessary information for calculating the flow rate and its associated uncertainty. ISO 5167 also

provides methodology for bespoke calibration of differential pressure meters.

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, or alternatively they can be used across

their calibrated range.

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 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

[1],[5]
devices and tertiary 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 Parts 2 to 6 of

ISO 5167.

b) ISO 5167-2 specifies orifice plates, which can be used with corner pressure tappings, D and D/2

pressure tappings , and flange pressure tappings.

c) ISO 5167-3 specifies ISA 1932 nozzles , long radius nozzles, and Venturi nozzles, which differ in

shape and in the position of the pressure tappings. Throat-tapped long-radius nozzles are included.

d) ISO 5167-4 specifies classical Venturi tubes .
e) ISO 5167-5 specifies cone meters.
f) ISO 5167-6 specifies wedge meters.

Aspects of safety are not dealt with in ISO 5167 (all parts). It is the responsibility of the user to ensure

that the system meets applicable safety regulations.

1) Orifice plates with 'vena contracta' pressure tappings are not considered in ISO 5167 (all parts).

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

succeeded by ISO in 1946.

3) In the USA, the classical Venturi tube is sometimes called the Herschel Venturi tube.

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oSIST prEN ISO 5167-5:2022
DRAFT INTERNATIONAL STANDARD ISO/DIS 5167-5:2021(E)
Measurement of fluid flow by means of pressure
differential devices inserted in circular cross-section
conduits running full —
Part 5:
Cone meters
1 Scope

This part of ISO 5167 specifies the geometry and method of use (installation and operating conditions)

of cone meters when they are inserted in a conduit running full to determine the flow rate of the fluid

flowing in the conduit.

As the uncertainty of an uncalibrated cone meter might be too high for a particular application, it might

be deemed essential to calibrate the flow meter in accordance with Clause 7.

This part of ISO 5167 also provides background information for calculating the flow rate and is

applicable in conjunction with the requirements given in ISO 5167-1.

This part of ISO 5167 is applicable only to cone meters in which the flow remains subsonic throughout

the measuring section and where the fluid can be considered as single-phase. Uncalibrated cone meters

can only be used within specified limits of pipe size, roughness, β, and Reynolds number. This part of

ISO 5167 is not applicable to the measurement of pulsating flow. It does not cover the use of uncalibrated

cone meters in pipes sized less than 50 mm or more than 500 mm, or where the pipe Reynolds numbers

4 7
are below 8 × 10 or greater than 1,2 × 10 .

A cone meter is a primary device which consists of a cone-shaped restriction held concentrically in the

centre of the pipe with the nose of the cone upstream. The design of cone meter defined in this part of

ISO 5167 has one or more upstream pressure tappings in the wall, and a downstream pressure tapping

positioned in the back face of the cone with the connection to a differential pressure transmitter being

a hole through the cone to the support bar, and then up through the support bar.

Alternative designs of cone meters are available; however, at the time of writing, there is insufficient

data to fully characterize these devices, and therefore, these meters shall be calibrated in accordance

with Clause 7.
2 Normative references

The following documents, in whole or in part, are normatively referenced in this document and are

indispensable for its application. For dated references, only the edition cited applies. For undated

references, the latest edition of the referenced document (including any amendments) applies.

ISO 4006, Measurement of fluid flow in closed conduits — Vocabulary and symbols

ISO 5167-1:2003, 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, ISO 5167-1, and the

following apply.
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ISO/DIS 5167-5:2021(E)
3.1
beta edge
maximum circumference of the cone
4 Principles of the method of measurement and computation

The principle of the method of measurement is based on the installation of the cone meter into a pipeline

in which a fluid is running full. Flow through a cone meter produces a differential pressure between the

upstream and downstream tappings.
The mass flow rate can be determined by Formulae (1) and (2):
C π
q = ε ()Dpβρ2Δ (1)
m 1
4 4
1−β
and
β =−1 (2)

where d is the diameter of the cone in the plane of the beta edge. This assumes that the diameter of

the pipe at the upstream tapping, D , is equal to the diameter of the pipe at the beta edge, D. Figure 1

TAP
shows that as the cone diameter increases, β decreases.
Key
Flow.
Figure 1 — Cone meter showing different values of β

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

Similarly, the value of the volume flow rate can be calculated since
q = (3)

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

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Computation of the flow rate, which is a purely arithmetic process, is performed by replacing the

different items on the right-hand side of Formula (1) by their numerical values. Formula (4) in 5.6 (or

the computed values in Table A.1) gives cone meter expansibility factors (ε). The values in Table A.1

are not intended for precise interpolation. Extrapolation is not permitted. However, the coefficient

of discharge, C, is generally dependent on the Reynolds number, Re, which is itself dependent on q ,

and has to be obtained by iteration (see ISO 5167-1:2003, Annex A for guidance regarding the choice of

iteration procedure and initial estimates).

The diameters, d and D, mentioned in Formulae (1) and (2) 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.

As the cone meter flow rate calculation is particularly sensitive to the pipe and cone diameter values

used, the user shall ensure that these are correctly entered into the flow computation calculations. For

example, care shall be taken to use the measured internal diameter rather than a nominal value.

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 Cone meters
5.1 Field of application

Uncalibrated cone meters can be used in pipes with diameters between 50 mm and 500 mm and with

0,45 ≤ β ≤ 0,75. Cone meters with β > 0,75 shall be calibrated. Cone meters with values of β < 0,45 are

not normally manufactured.
There are limits to the roughness and Reynolds number which shall be addressed.
5.2 General shape

Figure 2 shows a section through the centreline of a cone meter. Figure 4 shows other sections through

the meter to aid in the metrology of the cone meter. The letters used in the text refer to those shown in

Figure 2 and Figure 4.

The cone meter is made up of a pipe section of diameter, D, which houses the cone assembly with cone

diameter, d , the support structure for the cone, and the tappings for differential pressure measurement.

The cone assembly is installed such that the cone centreline is concentric to the centreline of the pipe

section, as per 5.2.13.
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Key
1 body pipe
2 cone element
3 support strut
4 high pressure tapping
5 low pressure tapping
6 cone nose
Flow.
NOTE 50 mm ≤ L ≤ 2D, as defined in 5.4.7.
Figure 2 — Geometric profile of cone meter

5.2.2 The design of the nose of the cone (for examples, see Figure 3) can be constructed as a machined

component or from an elbow. The nose shall be downstream of the plane of the centreline of the

upstream tapping(s). It is recommended that the nose be as short as practicable.
These designs shown in Figure 3 should not be considered exclusive.
a) Flat b) Pointed c) Curved d) Elbow
Figure 3 — Examples of different cone nose designs
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5.2.3 The pipe diameter, D, shall be measured at plane A of Figure 4. The number of measurements

shall be a minimum of four equally spaced around the pipe internal circumference. The arithmetic

mean value of these measurements shall be taken as the value of D in the calculations.

5.2.4 The pipe diameter shall also be measured at plane C of Figure 4 (shown as D in Figure 2). The

TAP

number of measurements at this plane shall be at least equal to the number of pressure tappings (with

a minimum of four).

5.2.5 No diameter at any point between plane C and 1D downstream of plane A from Figure 4 shall

differ from the pipe diameter, D, by more than 1,0 %.
Key
1 cone nose
Flow.
Figure 4 — Metrology data for a cone meter

5.2.6 The internal surface of the pipe section from plane C to plane A from Figure 4 shall be clean and

smooth, and the roughness criterion, Ra, should be as small as possible and shall be less than 10 D.

5.2.7 The cone assembly shall generally consist of a circular bifrustum (two truncated cones joined

at their widest points). The upstream frustum shall have a single internal angle, θ , of 22,5° ± 5° to the

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centreline of the frusta. The downstream frustum shall have a single internal angle, θ , of 64° ± 2,5° to

the centreline of the frusta.

5.2.8 The cone diameter, d , shall be measured at plane A of Figure 4. There shall be a minimum of

four measurements equally spaced around the cone external circumference.

The arithmetic mean value of these measurements shall be taken as the value of d in the calculations.

No diameter shall differ by more than 0,1 % from the value of the mean diameter. This requirement

is satisfied when the difference in length of any of the measured diameters conforms to the said

requirement with respect to the mean of the measured diameters.

5.2.9 The beta edge shall not be sharp. The radius of curvature, R , at the beta edge as shown in

Figure 5, shall be less than the smaller of 0,2 mm and 0,000 5 d .

5.2.10 The cone shall be such that two diameters situated on the same plane perpendicular to the axis

of revolution do not differ from the mean diameter by more than 0,1 %.

Figure 5 — Radius of curvature, R , at the beta edge shown, as examples, for fabricated and

machined cones

5.2.11 The cone surface shall be clean and smooth, and the roughness criterion, Ra, shall be as small as

possible and shall always be less than 5 × 10 d .

5.2.12 The supporting structure for the cone shall present as small a restriction to the flow as

practical, whilst ensuring that the structural integrity of the cone meter is not impaired over the range

of conditions anticipated. The cone assembly may optionally include gussets that provide additional

mechanical support.

5.2.13 The lateral and angular deviations of the cone from the centreline of the pipe section shall be

measured.

The distance between the widest part of the cone and the adjacent pipe internal wall shall be measured

(see plane A of Figure 4, labelled K , K , K , K ). There shall be a minimum of four measurements equally

1 2 3 4

spaced around the external circumference of the cone. The difference between each measurement and

the mean of those measurements shall be no greater than 5,0 %.

The distance between the cone nose and the adjacent pipe internal wall shall also be measured (see

plane B of Figure 4, labelled J , J , J , J ). There shall be a minimum of four measurements equally spaced

1 2 3 4

around the external circumference of the cone. The difference between each measurement and the

mean of those measurements shall be no greater than 5,0 %.

The angular deviation of the cone shall be measured and should be no greater than 2,0° in either the

horizontal (θ ) or vertical (θ ) from the pipe centreline at the cone nose, as shown in Figure 4.

HORZ VERT

The lateral deviation of the cone shall be measured and should be no greater than 0,01D in either the

horizontal or vertical from the pipe centreline at the cone nose, as shown in Figure 4.

© ISO 2021 – All rights reserved
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oSIST prEN ISO 5167-5:2022
ISO/DIS 5167-5:2021(E)

5.2.14 Consideration shall be taken in the design of the cone meter and its installation to ensure that

the effects of pressure, temperature, and resonance over the entire range of conditions that the flow

meter may see over its operational life do not result in mechanical failure.

In applications where flow conditions produce significant vibration, the use of gussets is recommended.

5.3 Material and manufacture

5.3.1 The cone meter may be manufactured from any material, provided that the cone meter is in

accordance with the foregoing description and will remain so during use.

5.3.2 For fabricated cones, the cone shall include pressure relief vent holes through the downstream

face to ensure the structural stability of the cone under rapid pressure changes.

5.4 Pressure tappings

5.4.1 The upstream tapping shall be made in the form of a pipe wall pressure tapping.

5.4.2 The diameter of the upstream tapping sha
...