Non-destructive testing - Leak testing - Calibration of reference leaks for gases (ISO 20486:2017)

This draft European Standard specifies the calibration of those leaks that are used for the adjustment of leak detectors for the determination of leakage rate in everyday use. The preferred calibration method in this case is a comparison with a standard leak. In this way the leaks used for routine use become traceable to a primary standard as the ISO 9000 series of standards require. The comparison procedures are preferably applicable to helium leaks, because this test gas can be selectively measured by a mass spectrometer leak detector (MSLD) (the definition of MLSD is given in EN 1330-8). Calibration by comparison (see methods A and B below) with known standard leaks is easily possible for leaks with reservoir and leakage rates below 10-7Pa.m3/s. From 10-7 Pa.m3/s to 10-4 Pa.m3/s no leaks reliable enough to be used as transfer standard exist. Leaks in this range can only be calibrated by measurement of flow in a calibrated capillary tube (see method C below). Leakage rates greater than 10-4 Pa.m3/s can be measured by flow meters calibrated against primary national standards.

Zerstörungsfreie Prüfung - Dichtheitsprüfung - Kalibrieren von Referenzlecks für Gase (ISO 20486:2017)

Dieser Entwurf einer Europäischen Norm spezifiziert die Kalibrierung der Lecks, die für die Justierung von Leckdetektoren für die Bestimmung von Leckageraten im täglichen Gebrauch verwendet werden. Eine Art des Kalibrierverfahrens ist ein Vergleich mit einem normierten Leck. Auf diese Weise werden die Lecks zur routinemäßigen Verwendung auf eine primäre Norm rückführbar, wie es nach der Normenreihe ISO 9000 erforderlich ist. Bei anderen Kalibrierverfahren wurde QpV direkt gemessen oder QpV wurde über ein bekanntes Volumen berechnet.
Die Vergleichsverfahren gelten vorzugsweise für Heliumlecks, da dieses Prüfgas selektiv mithilfe eines Massenspektrometerleckdetektors (en: mass spectrometer leak detector, MSLD) gemessen werden kann (die Definition des MSLD wird in ISO/DIS 20484 angegeben).
Die Kalibrierung durch Vergleich (siehe Verfahren A, As, B und Bs unten) mit bekannten Normlecks ist ein-fach möglich für Lecks mit Reservoir und Leckageraten unter 10–7 Pa m3/s.
Bild 1 zeigt einen Überblick, in dem Bereiche verschiedener Kalibrierverfahren empfohlen werden.
...
Bild 1a — Kalibrierbereich für Kalibrierung durch Vergleich
...
Bild 1b — Kalibrierbereich für Kalibrierung durch

Essais non destructifs - Contrôle d'étanchéité - Étalonnage des fuites de référence des gaz (ISO 20486:2017)

ISO 20486:2017 spécifie l'étalonnage des fuites utilisées dans le réglage des détecteurs de fuites et la détermination des flux de fuite, dans le cadre d'un usage quotidien. Un type de méthode d'étalonnage est une comparaison avec une fuite de référence. Ainsi, les fuites faisant l'objet d'un usage courant deviennent traçables par rapport à un étalon primaire. Dans d'autres méthodes d'étalonnage, la valeur de la pression de vapeur était mesurée directement ou calculée sur un volume connu.
Les modes opératoires d'étalonnage par comparaison sont de préférence applicables aux fuites d'hélium, car ce gaz d'essai peut être mesuré individuellement au moyen d'un détecteur de fuites à spectromètre de masse (DFSM) (la définition de DFSM est donnée dans l'ISO 20484).
L'étalonnage par comparaison (voir méthodes A, As, B et Bs ci-dessous) qui utilise des fuites de référence connues est facilement applicable aux fuites de réservoir et à celles dont les flux de fuite sont inférieurs à 10−7 Pa·m3/s.

Neporušitveno preskušanje - Preiskava tesnosti - Umerjanje referenčne tesnosti za plin (ISO 20486:2017)

Ta osnutek evropskega standarda določa umerjanje uhajanj, ki se uporabljajo za nastavitev detektorjev uhajanja z namenom določanja stopnje uhajanja pri vsakodnevni uporabi. Prednostna metoda umerjanja je v tem primeru primerjava s standardnim uhajanjem. Na ta način postanejo uhajanja pri rutinski uporabi sledljiva na podlagi primarnega standarda, kakor zahteva skupina standardov ISO 9000. Postopki primerjave se prednostno uporabljajo za uhajanje helija, saj je ta preskusni plin mogoče selektivno meriti z detektorjem uhajanja z masnim spektrometrom (MSLD) (opredelitev MSLD je podana v standardu EN 1330-8). Umerjanje na podlagi primerjave (glejte metodi A in B v nadaljevanju) z znanimi standardnimi uhajanji je enostavno izvedljivo za uhajanje iz rezervoarja in stopnjo uhajanja pod 10-7 Pa x m3/s. V območju od 10-7 Pa x m3/s do 10-4 Pa x m3/s uhajanja niso dovolj zanesljiva, da bi jih lahko uporabili kot standard za prenos. Uhajanja v tem območju je mogoče umerjati samo z merjenjem pretoka v umerjeni kapilarni cevi (glejte metodo C v nadaljevanju). Stopnje uhajanja, ki so večje od 10-4 Pa x m3/s je mogoče izmeriti z merilniki pretoka, ki so umerjeni v skladu s primarnimi nacionalnimi standardi.

General Information

Status
Published
Public Enquiry End Date
06-Nov-2016
Publication Date
20-May-2018
Current Stage
6060 - National Implementation/Publication (Adopted Project)
Start Date
15-Feb-2018
Due Date
22-Apr-2018
Completion Date
21-May-2018

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SLOVENSKI STANDARD
SIST EN ISO 20486:2018
01-julij-2018
1DGRPHãþD
SIST EN 13192:2002
SIST EN 13192:2002/AC:2004

1HSRUXãLWYHQRSUHVNXãDQMH3UHLVNDYDWHVQRVWL8PHUMDQMHUHIHUHQþQHWHVQRVWL]D

SOLQ ,62

Non-destructive testing - Leak testing - Calibration of reference leaks for gases (ISO

20486:2017)

Zerstörungsfreie Prüfung - Dichtheitsprüfung - Kalibrieren von Referenzlecks für Gase

(ISO 20486:2017)

Essais non destructifs - Contrôle d'étanchéité - Étalonnage des fuites de référence des

gaz (ISO 20486:2017)
Ta slovenski standard je istoveten z: EN ISO 20486:2018
ICS:
19.100 Neporušitveno preskušanje Non-destructive testing
SIST EN ISO 20486:2018 en,fr,de

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

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SIST EN ISO 20486:2018
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SIST EN ISO 20486:2018
EN ISO 20486
EUROPEAN STANDARD
NORME EUROPÉENNE
February 2018
EUROPÄISCHE NORM
ICS 19.100 Supersedes EN 13192:2001
English Version
Non-destructive testing - Leak testing - Calibration of
reference leaks for gases (ISO 20486:2017)

Essais non destructifs - Contrôle d'étanchéité - Zerstörungsfreie Prüfung - Dichtheitsprüfung -

Étalonnage des fuites de référence des gaz (ISO Kalibrieren von Referenzlecks für Gase (ISO

20486:2017) 20486:2017)
This European Standard was approved by CEN on 23 December 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: Rue de la Science 23, B-1040 Brussels

© 2018 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 20486:2018 E

worldwide for CEN national Members.
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SIST EN ISO 20486:2018
EN ISO 20486:2018 (E)
Contents Page

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

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SIST EN ISO 20486:2018
EN ISO 20486:2018 (E)
European foreword

This document (EN ISO 20486:2018) has been prepared by Technical Committee ISO/TC 135 "Non-

destructive testing" in collaboration with Technical Committee CEN/TC 138 “Non-destructive testing”,

the secretariat of which is held by AFNOR.

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 August 2018, and conflicting national standards shall

be withdrawn at the latest by August 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 13192:2001.

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 20486:2017 has been approved by CEN as EN ISO 20486:2018 without any modification.

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SIST EN ISO 20486:2018
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SIST EN ISO 20486:2018
INTERNATIONAL ISO
STANDARD 20486
First edition
2017-12
Non-destructive testing — Leak
testing — Calibration of reference
leaks for gases
Essais non destructifs — Contrôle d'étanchéité — Étalonnage des
fuites de référence des gaz
Reference number
ISO 20486:2017(E)
ISO 2017
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SIST EN ISO 20486:2018
ISO 20486:2017(E)
COPYRIGHT PROTECTED DOCUMENT
© 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

the requester.
ISO copyright office
Ch. de Blandonnet 8 • CP 401
CH-1214 Vernier, Geneva, Switzerland
Tel. +41 22 749 01 11
Fax +41 22 749 09 47
copyright@iso.org
www.iso.org
ii © ISO 2017 – All rights reserved
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SIST EN ISO 20486:2018
ISO 20486:2017(E)
Contents Page

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

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

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

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

4 Nominal leakage rates .................................................................................................................................................................................... 3

5 Classification of leaks ...................................................................................................................................................................................... 3

5.1 Permeation leak ..................................................................................................................................................................................... 3

5.2 Conductance leaks ............................................................................................................................................................................... 3

5.2.1 Capillary leak ...................................................................................................................................................................... 3

5.2.2 Aperture leak (orifice) ................................................................................................................................................ 4

5.2.3 Compressed powder leak ......................................................................................................................................... 4

6 Calibration by comparison ......................................................................................................................................................................... 4

6.1 Methods A, A , B and B ....................................................................................................................................................................

s s 4

6.2 Applicability of comparison methods ................................................................................................................................. 4

6.3 Preparation of leaks and apparatus ...................................................................................................................................... 5

6.3.1 Leak detector ...................................................................................................................................................................... 5

6.3.2 Connection to the leak detector .......................................................................................................................... 5

6.3.3 Temperature accommodation .............................................................................................................................. 7

6.4 Measurement ............................................................................................................................................................................................ 7

6.4.1 Set-up ......................................................................................................................................................................................... 7

6.4.2 General measurement sequence ........................................................................................................................ 7

6.5 Evaluation for methods A, A , B and B (Comparison) ......................................................................................... 8

s s

6.5.1 Determination of leakage rate .............................................................................................................................. 8

6.5.2 Influence factors to measurement uncertainty ..................................................................................... 9

7 Volumetric calibration.................................................................................................................................................................................10

7.1 Direct flow (Method C) ..................................................................................................................................................................10

7.1.1 General...................................................................................................................................................................................10

7.1.2 Equipment ..........................................................................................................................................................................10

7.1.3 Preparation of leaks and apparatus .............................................................................................................10

7.1.4 Measurement ...................................................................................................................................................................11

7.1.5 Evaluation for Method C (direct flow measurement) ...................................................................13

7.2 Leak measurement under water (Method D) ............................................................................................................14

7.2.1 General...................................................................................................................................................................................14

7.2.2 Equipment ..........................................................................................................................................................................14

7.2.3 Preparation of leaks and apparatus .............................................................................................................14

7.2.4 Measurement ...................................................................................................................................................................15

7.2.5 Evaluation for Method D ........................................................................................................................................16

7.2.6 Influence factors to measurement uncertainty ..................................................................................17

7.3 Calibration by (volumetric) gas meter (Method E) ..............................................................................................17

7.3.1 General...................................................................................................................................................................................17

7.3.2 Equipment ..........................................................................................................................................................................18

7.3.3 Preparation of leaks and apparatus .............................................................................................................18

7.3.4 Measurement ...................................................................................................................................................................18

7.3.5 Evaluation for Method E (gas meter) ..........................................................................................................18

7.3.6 Influence factors to measurement uncertainty ..................................................................................19

7.4 Calibration by pressure change in a known volume (Method F) ..............................................................19

7.4.1 General...................................................................................................................................................................................19

7.4.2 Preparation of leaks and apparatus .............................................................................................................20

7.4.3 Measurement ...................................................................................................................................................................22

7.4.4 Special situation in vacuum chambers ......................................................................................................23

7.4.5 Evaluation for Method F (pressure change) ..........................................................................................25

7.4.6 Influence factors to measurement uncertainty ..................................................................................25

© ISO 2017 – All rights reserved iii
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SIST EN ISO 20486:2018
ISO 20486:2017(E)

7.5 Calibration by volume change at constant pressure (Method G) .............................................................26

7.5.1 Equipment ..........................................................................................................................................................................26

7.5.2 Preparation of leaks and apparatus .............................................................................................................26

7.5.3 Measurement ...................................................................................................................................................................26

7.5.4 Evaluation for Method G (volume change at constant pressure)........................................27

8 General influences ...........................................................................................................................................................................................28

9 Report ...........................................................................................................................................................................................................................28

10 Labelling of reference leaks ...................................................................................................................................................................29

11 Handling of reference leaks ...................................................................................................................................................................29

11.1 General ........................................................................................................................................................................................................29

11.2 Permeation leaks (normally with reservoir fitted the leak outlet) .........................................................29

11.3 Conductance leaks (normally without reservoir) ..................................................................................................29

Annex A (informative) Calculation of leakage rate decrease due to tracer gas depletion in

the reservoir ..........................................................................................................................................................................................................30

Bibliography .............................................................................................................................................................................................................................32

iv © ISO 2017 – All rights reserved
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SIST EN ISO 20486:2018
ISO 20486:2017(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 on 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 the following

URL: www.iso.org/iso/foreword.html.

This document was prepared by Technical Committee ISO/TC 135, Non-destructive testing,

Subcommittee SC 6, Leak testing.
© ISO 2017 – All rights reserved v
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SIST EN ISO 20486:2018
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SIST EN ISO 20486:2018
INTERNATIONAL STANDARD ISO 20486:2017(E)
Non-destructive testing — Leak testing — Calibration of
reference leaks for gases
1 Scope

This document specifies the calibration of those leaks that are used for the adjustment of leak detectors

for the determination of leakage rate in everyday use. One type of calibration method is a comparison

with a reference leak. In this way, the leaks used for routine use become traceable to a primary standard.

In other calibration methods, the value of vapour pressure was measured directly or calculated over a

known volume.

The comparison procedures are preferably applicable to helium leaks, because this test gas can be

selectively measured by a mass spectrometer leak detector (MSLD) (the definition of MSLD is given in

ISO 20484).

Calibration by comparison (see methods A, A , B and B below) with known reference leaks is easily

s s
−7 3
possible for leaks with reservoir and leakage rates below 10 Pa·m /s.
Figure 1 gives an overview of the different recommended calibration methods.
a) Calibration by comparison
© ISO 2017 – All rights reserved 1
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SIST EN ISO 20486:2018
ISO 20486:2017(E)
b) Calibration by direct measurement
Key
X leakage rate in Pa·m /s C Method C
A Method A D Method D
B Method B E Method E
A Method A F Method F
s s
B Method B G Method G
s s
normal range possible range
Figure 1 — Calibration ranges
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.

ISO 20484, Non-destructive testing — Leak testing — Vocabulary
3 Terms and definitions

For the purposes of this document, the terms and definitions given in ISO 20484 and the following apply.

ISO and IEC maintain terminological databases for use in standardization at the following addresses:

— ISO Online browsing platform: available at https://www.iso.org/obp
— IEC Electropedia: available at http://www.electropedia.org/
2 © ISO 2017 – All rights reserved
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SIST EN ISO 20486:2018
ISO 20486:2017(E)
3.1
unknown leak

leak having a stable and repeatable leakage rate of known order of magnitude that can be determined

by calibration
3.2
reference leak
calibrated leak which may be used to calibrate another leak

Note 1 to entry: The uncertainty of the reference leak is lower than the required uncertainty of the leak to be

calibrated.
3.3
calibration

set of operations which establish, under specified conditions, the relationship between leakage rate

values represented by an unknown leak and the corresponding known values of the leakage rate

Note 1 to entry: In the case of calibration by comparison, the known values of the leakage rate are represented by

a reference leak.

Note 2 to entry: Normally, the result of a calibration is given as the leakage rate value for the reference leak with

a standard uncertainty.
3.4
nominal leakage rate
leakage rate of a leak calculated for specified reference conditions

Note 1 to entry: In leak detection, leakage rates are commonly given in units of pV-throughput (Pa·m /s, mbar l/s,

Std cm /min). These are only a precise measure of gas flow if the temperature is given and kept constant. Flow

units such as mass flow (g/y) or molar flow (mol/s) are sometimes used to overcome this problem.

4 Nominal leakage rates

Calibrated leaks are only comparable under the same reference conditions. Nominal leakage rates shall

be used for comparison. Recommended reference conditions are:
— Ambient temperature: 20 °C
— Atmospheric exhaust pressure: 1 000 mbar
— Vacuum exhaust pressure: < 100 mbar

The reference inlet pressure is given by the leak reservoir pressure or the application requirement.

5 Classification of leaks
5.1 Permeation leak

This type of leak is normally made with a tracer gas reservoir. It has the best long-term stability but an

appreciable temperature coefficient (approximately 3,5 %/K). Typical leakage rates are in the range

−10 3 −4 3
from 10 Pa·m /s to 10 Pa·m /s.
5.2 Conductance leaks
5.2.1 Capillary leak

This type of leak is available with or without a tracer gas reservoir. It has a low temperature coefficient

(approximately 0,3 %/K) but easily blocks if not handled with care. Typical leakage rates are greater

−7 3
than 10 Pa·m /s.
© ISO 2017 – All rights reserved 3
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SIST EN ISO 20486:2018
ISO 20486:2017(E)
5.2.2 Aperture leak (orifice)

Orifices are seldom used as reference leaks in practice, as they are difficult to manufacture and even

more prone to blocking than capillaries.

NOTE Critical flow orifices are a form of aperture leak that is commonly found in industry, but are out of the

scope of this document.
5.2.3 Compressed powder leak

This type of leak uses metal powder compressed into a tube. They are usually offered without reservoir.

They are used for routine check of the sensitivity of leak detectors but they are not stable enough to be

used as calibrated leaks. Their suitability depends on how well controlled the storage and operating

conditions are, and on the required uncertainty.
6 Calibration by comparison
6.1 Methods A, A , B and B
s s

There are two ways of calibrating leaks by comparison with known reference leaks. Both methods

require the knowledge of the order of magnitude of the leakage rate to be measured. The methods

differ in using one or two reference leaks, resulting in different uncertainties of measurement. In the

following, the two methods are designated as A and B:

— Method A: Comparison to one reference leak normally with a leakage rate of the same order of

magnitude, calibration with vacuum method.

— Method A : Comparison to one reference leak normally with a leakage rate of the same order of

magnitude, calibration with sniffing method.

— Method B: Comparison to two reference leaks with leakage rates normally lying on either side of the

unknown leakage rate, calibration with vacuum method.

— Method B : Comparison to two reference leaks with leakage rates normally lying on either side of

the unknown leakage rate. Calibration with sniffing method.

Method A is most suitable for use on site as only one reference leak is used. It is generally applicable

but is most reliable when the leakage rate of the unknown is close to that of the reference leak. This is

because the measurement uncertainty is directly dependent on the linearity of the leak detector in use.

As the linearity error cannot be measured independently, it needs to be estimated. To keep the linearity

error small, the operating characteristics of leak detector should not change during calibration (e.g.

automatic ranging should be disabled).

For more precise calibrations, where a more reliable measure of uncertainty is required or if a reference

leak with a leakage rate close to the unknown is not available Method B should be used. By the use of

two reference leaks, the non-linearity of the leak detector is accounted for.
6.2 Applicability of comparison methods

Since comparison of leaks is not a fundamental measurement method, it relies on the stability of the

transfer device and cleanliness of the ambient gas atmosphere. Moreover, the temperature dependence

of the reference and unknown leaks shall be taken into account.

The most stable and clean conditions are achieved for leaks with exhaust into vacuum and a mass

spectrometer leak detector as transfer device measuring the partial pressure generated by the leaks in

vacuum. Under these conditions, all interfering background gases are reduced to a minimum so that the

zero point of the transfer device is defined and stable.
4 © ISO 2017 – All rights reserved
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SIST EN ISO 20486:2018
ISO 20486:2017(E)

For leaks with exhaust into the atmosphere and measurement by sniffing gas, more conditions shall be

controlled. These are:

— the background level of tracer gas shall be as low as possible and as stable as possible;

— the total gas flow rate of the sniffer shall be high enough to take up the total tracer gas flow out of

the leak;

— the aspiration of the sniffer (the coupling to the leak exhaust) shall be of suitable geometry to make

sure that the atmospheric gas flow across the leak exhaust takes up the whole tracer gas flow from

the leak opening.

As a consequence, the measurement uncertainty is appreciably higher for sniffer leaks than for

vacuum leaks.

Methods by comparison are therefore applicable but not preferable for the calibration of sniffer leaks

(with exhaust to atmosphere).
6.3 Preparation of leaks and apparatus
6.3.1 Leak detector

The leak detector (LD) used as a transfer device shall be set up according to the manufacturer’s manual.

The warm-up time shall be at least 2 h.
6.3.2 Connection to the leak detector

The reference and unknown leaks are connected to the leak detector used as the transfer instrument.

The connection shall be kept continuously until the measurement is completed. This includes thermal

[1]
accommodation .

In the case of vacuum leaks, they are connected to the inlet flange and pumped with their valves (if any)

open for at least 30 min to remove any tracer gas that can have accumulated in seals or valves. For the

calibration of more than one leak, a separate pumping syste
...

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