EN ISO 6145-6:2017

Gas analysis - Preparation of calibration gas mixtures using dynamic methods - Part 6: Critical flow orifices (ISO 6145-6:2017)

ISO 6145-6:2017 specifies a method for the dynamic preparation of calibration gas mixtures containing at least two gases (usually one of them is a complementary gas) from pure gases or gas pre-mixtures using critical flow orifices systems.
The method applies principally to the preparation of mixtures of non-reactive gases that do not react with any of the materials forming the gas circuit inside the critical flow orifices system or auxiliary equipment. It has the merit of allowing multi-component mixtures to be prepared as readily as binary mixtures if an appropriate number of critical flow orifices are used.
By selecting appropriate combinations of critical flow orifices, a dilution ratio of 1 × 104 is achievable.
Although it is more particularly applicable to the preparation of gas mixtures at atmospheric pressure, the method also offers the possibility of preparing calibration gas mixtures at pressures greater than atmospheric. The upstream pressure will need to be at least two times higher than downstream pressure.
The range of flow rates covered by this document extends from 1 ml/min to 10 l/min.

Gasanalyse - Herstellung von Kalibriergasgemischen mit Hilfe von dynamisch-volumetrischen Verfahren - Teil 6: Kritische Düsen (ISO 6145-6:2017)

Analyse des gaz - Préparation des mélanges de gaz pour étalonnage à l'aide de méthodes volumétriques dynamiques - Partie 6: Orifices de débit critiques (ISO 6145-6:2017)

L'ISO 6145-6:2017 décrit une méthode de préparation dynamique de mélanges de gaz d'étalonnage, contenant au moins deux gaz (l'un d'eau étant généralement un gaz de complément), à partir de gaz purs ou de pré-mélanges de gaz à l'aide de systèmes à orifices critiques.
La méthode s'applique principalement à la préparation de mélanges de gaz non réactifs qui ne réagissent avec aucun des matériaux formant le circuit de gaz à l'intérieur du système à orifices critiques ou d'un équipement auxiliaire. Elle a le mérite de permettre la préparation de mélanges à plusieurs constituants aussi facilement que des mélanges à deux constituants si un nombre approprié d'orifices critiques est utilisé.
En choisissant des combinaisons appropriées d'orifices critiques et en utilisant des gaz purs, il est possible d'atteindre un rapport de dilution de 1 x 104.
Bien qu'elle soit plus particulièrement applicable à la préparation de mélanges de gaz à la pression atmosphérique, cette méthode offre également la possibilité de préparer des mélanges de gaz d'étalonnage à des pressions supérieures à la pression atmosphérique. La pression amont devra être au moins deux fois plus élevée que la pression aval.
La gamme de débits couverte par le présent document s'étend de 1 ml/min à 10 l/min.

Analiza plinov - Priprava kalibracijskih plinskih zmesi z uporabo dinamičnih volumetričnih metod - 6. del: Kritične šobe (ISO 6145-6:2017)

Ta dokument določa metodo dinamične priprave kalibracijskih plinskih zmesi, ki vsebujejo najmanj dva plina (običajno je eden komplementarni plin), iz čistih plinov ali vnaprej pripravljenih mešanic plinov, ki uporabljajo sisteme s kritičnimi šobami.
Ta metoda se uporablja predvsem pri pripravi mešanic nereaktivnih plinov, ki ne reagirajo z nobenim materialom, ki tvori plinski krog znotraj sistema kritičnih šob ali pomožne opreme. Njena prednost je v tem, da omogoča pripravo večkomponentnih mešanic na enak način kot pri dvokomponentnih mešanicah, če je uporabljeno ustrezno število kritičnih šob.
Z izbiro ustreznih kombinacij kritičnih šob je mogoče doseči razmerje redčenja 1 × 104. Čeprav je metoda še zlasti primerna za pripravo plinskih zmesi pri atmosferskem tlaku, ponuja tudi možnost priprave kalibracijskih plinskih zmesi pri tlakih, večjih od atmosferskega tlaka. Tlak proti toku mora biti vsaj dvakrat večji od tlaka v smeri toka.
Razpon pretoka, ki je zajet v tem dokumentu, obsega od 1 ml/min do 10 l/min.

General Information

• Status: Published
• Publication Date: 15-Aug-2017
• ICS: 71.040.40 - Chemical analysis
• Technical Committee: CEN/TC 238 - Test gases, test pressures and categories of appliances
• Drafting Committee: CEN/TC 238 - Test gases, test pressures and categories of appliances
• Current Stage: 6060 - Definitive text made available (DAV) - Publishing
• Start Date: 16-Aug-2017
• Completion Date: 16-Aug-2017
• Ref Project: SIST EN ISO 6145-6:2017 - Gas analysis - Preparation of calibration gas mixtures using dynamic methods - Part 6: Critical flow orifices (ISO 6145-6:2017)

Relations

• Replaces: EN ISO 6145-6:2008 - Gas analysis - Preparation of calibration gas mixtures using dynamic volumetric methods - Part 6: Critical orifices (ISO 6145-6:2003)
• Effective Date: 08-Jun-2022

Standards Content (Sample)

SLOVENSKI STANDARD
01-oktober-2017
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SIST EN ISO 6145-6:2008
$QDOL]DSOLQRY3ULSUDYDNDOLEUDFLMVNLKSOLQVNLK]PHVL]XSRUDERGLQDPLþQLK
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Gas analysis - Preparation of calibration gas mixtures using dynamic methods - Part 6:
Critical flow orifices (ISO 6145-6:2017)
Gasanalyse - Herstellung von Kalibriergasgemischen mit Hilfe von dynamisch-
volumetrischen Verfahren - Teil 6: Kritische Düsen (ISO 6145-6:2017)
Analyse des gaz - Préparation des mélanges de gaz pour étalonnage à l'aide de
méthodes volumétriques dynamiques - Partie 6: Orifices de débit critiques (ISO 6145-
6:2017)
Ta slovenski standard je istoveten z: EN ISO 6145-6:2017
ICS:
71.040.40 Kemijska analiza Chemical analysis
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EN ISO 6145-6
EUROPEAN STANDARD
NORME EUROPÉENNE
August 2017
EUROPÄISCHE NORM
ICS 71.040.40 Supersedes EN ISO 6145-6:2008
English Version
Gas analysis - Preparation of calibration gas mixtures
using dynamic methods - Part 6: Critical flow orifices (ISO
6145-6:2017)
Analyse des gaz - Préparation des mélanges de gaz Gasanalyse - Herstellung von Kalibriergasgemischen
pour étalonnage à l'aide de méthodes volumétriques mit Hilfe von dynamisch-volumetrischen Verfahren -
dynamiques - Partie 6: Orifices de débit critiques (ISO Teil 6: Kritische Düsen (ISO 6145-6:2017)
6145-6:2017)
This European Standard was approved by CEN on 7 August 2017.

CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this
European Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references
concerning such national standards may be obtained on application to the CEN-CENELEC Management Centre or to any CEN
member.
This European Standard exists in three official versions (English, French, German). A version in any other language made by
translation under the responsibility of a CEN member into its own language and notified to the CEN-CENELEC Management
Centre has the same status as the official versions.

CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia,
Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania,
Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland,
Turkey and United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION

EUROPÄISCHES KOMITEE FÜR NORMUNG

CEN-CENELEC Management Centre: Avenue Marnix 17, B-1000 Brussels
© 2017 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 6145-6:2017 E
worldwide for CEN national Members.

Contents Page
European foreword . 3

European foreword
This document (EN ISO 6145-6:2017) has been prepared by Technical Committee ISO/TC 158 “Analysis
of gases”.
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 February 2018, and conflicting national standards
shall be withdrawn at the latest by February 2018.
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CEN shall not be held responsible for identifying any or all such patent rights.
This document supersedes EN ISO 6145-6:2008.
According to the CEN-CENELEC Internal Regulations, the national standards organizations of the
following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria,
Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia,
France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta,
Netherlands, Norway, Poland, Portugal, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland,
Turkey and the United Kingdom.
Endorsement notice
The text of ISO 6145-6:2017 has been approved by CEN as EN ISO 6145-6:2017 without any
modification.
INTERNATIONAL ISO
STANDARD 6145-6
Third edition
2017-07
Gas analysis — Preparation of
calibration gas mixtures using
dynamic methods —
Part 6:
Critical flow orifices
Analyse des gaz — Préparation des mélanges de gaz pour étalonnage
à l’aide de méthodes volumétriques dynamiques —
Partie 6: Orifices de débit critiques
Reference number
ISO 6145-6:2017(E)
©
ISO 2017
ISO 6145-6:2017(E)
© ISO 2017, Published in Switzerland
All rights reserved. Unless otherwise specified, 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
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ii © ISO 2017 – All rights reserved

ISO 6145-6:2017(E)
Contents Page
Foreword .iv
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Symbols . 4
5 Principle . 5
6 Calculation of mass flow rate and volume flow rate . 6
6.1 General . 6
6.2 Calculation under ideal conditions . 7
6.2.1 Calculation of mass flow rate . 7
6.2.2 Calculation of volume flow rates . 7
6.3 Calculation of mass flow rate using flow calibration with pure nitrogen . 8
6.4 Flow rate uncertainty calculation . 9
6.4.1 General. 9
6.4.2 Sources of uncertainty . 9
6.4.3 Uncertainty estimation . .10
7 Calculation of amount of substance fraction and volume fraction and associated
uncertainty evaluation .10
7.1 General .10
7.2 Amount of substance fraction calculation and associated uncertainty .10
7.2.1 Case of gases with purity ≥ 99,99 % .10
7.2.2 Case of pre-mixtures . .13
7.3 Remarks about uncertainty for the amount fraction .15
8 Application to the preparation of gas mixtures .15
8.1 Example of a mixing system .15
8.2 Conditions of operation .16
9 Calibration and verification .17
9.1 General .17
9.2 Calibration of the mixing system in the flow rate .17
9.3 Calibration of the mixing system with gas mixtures for a specific gas and concentration .17
9.4 Verification of the mixing system .17
Annex A (informative) Example of calculation of isentropic coefficient, viscosity and critical
flow coefficient .19
Annex B (informative) Calculation of mass and volume flow rates under real conditions .21
Annex C (informative) Example of flow calculation for toroidal critical flow orifices under
ideal and real conditions .23
Annex D (informative) Calculation of mass flow rate using flow calibration with pure
nitrogen: examples .25
Bibliography .27
ISO 6145-6:2017(E)
Foreword
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