IEC 62990-2:2021

Workplace atmospheres - Part 2: Gas detectors - Selection, installation, use and maintenance of detectors for toxic gases and vapours

IEC 62990-2:2021 gives guidance on the selection, installation, use and maintenance of electrical equipment used for the measurement of toxic gases and vapours in workplace atmospheres. The primary purpose of such equipment is to ensure safety of personnel and property by providing an indication of the concentration of a toxic gas or vapour and warning of its presence.
This document is applicable to equipment whose purpose is to provide an indication, alarm or other output function to give a warning of the presence of a toxic gas or vapour in the atmosphere and in some cases to initiate automatic or manual protective actions. It is applicable to equipment in which the sensor automatically generates an electrical signal when gas is present.
For the purposes of this document, equipment includes:
a) fixed equipment;
b) transportable equipment, and
c) portable equipment.
This document is intended to cover equipment defined within IEC 62990-1, but can provide useful information for equipment not covered by that document.

Atmosphères des lieux de travail - Partie 2: Détecteurs de gaz - Sélection, installation, utilisation et maintenance des détecteurs de gaz et de vapeurs toxiques

IEC 62990-2:2021 donne des recommandations pour la sélection, l’installation, l’utilisation et la maintenance du matériel électrique utilisé pour le mesurage des gaz et des vapeurs toxiques dans les atmosphères des lieux de travail. Le principal objectif de ce type de matériel est d’assurer la sécurité des personnes et des biens en fournissant une indication de la concentration d’un gaz ou d’une vapeur toxique et en avertissant de sa présence.
Le présent document s’applique aux matériels dont l’objectif principal est de donner une indication, une alarme ou une autre fonction de sortie pour avertir de la présence d’un gaz ou d’une vapeur toxique dans l’atmosphère et, dans certains cas, de déclencher des actions protectrices automatiques ou manuelles. Il s’applique aux matériels dont le capteur génère automatiquement un signal électrique en présence de gaz.
Pour les besoins du présent document, les matériels comprennent:
a) le matériel fixe;
b) le matériel transportable; et
c) le matériel portable.
Le présent document est destiné à couvrir les matériels définis dans l’IEC 62990-1, mais peut fournir des informations utiles pour des matériels non couverts par ce document.

General Information

• Status: Published
• Publication Date: 03-Jun-2021
• ICS: 29.260.20 - Electrical apparatus for explosive atmospheres
• Technical Committee: TC 31 - Equipment for explosive atmospheres
• Drafting Committee: JWG 45 - TC 31/JWG 45
• Current Stage: PPUB - Publication issued
• Start Date: 28-May-2021
• Completion Date: 04-Jun-2021

Standards Content (Sample)

IEC 62990-2
Edition 1.0 2021-06
INTERNATIONAL
STANDARD
colour
inside
Workplace atmospheres –
Part 2: Gas detectors – Selection, installation, use and maintenance of detectors
for toxic gases and vapours
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form
or by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from
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copyright or have an enquiry about obtaining additional rights to this publication, please contact the address below or
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About the IEC
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International Standards for all electrical, electronic and related technologies.

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IEC 62990-2
Edition 1.0 2021-06
INTERNATIONAL
STANDARD
colour
inside
Workplace atmospheres –
Part 2: Gas detectors – Selection, installation, use and maintenance of detectors

for toxic gases and vapours
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 29.260.20 ISBN 978-2-8322-9746-9

– 2 – IEC 62990-2:2021 © IEC 2021
CONTENTS
FOREWORD . 4
INTRODUCTION . 6
1 Scope . 7
2 Normative references . 7
3 Terms and definitions . 7
4 Properties and detection of toxic gases and vapours . 13
4.1 Properties and detection . 13
4.2 The difference between detecting gases and vapours . 14
4.3 Effects of water vapour on detection . 17
4.4 Effects of temperature and pressure on detection . 17
4.5 Effects of corrosion on detection . 17
4.6 Detection by oxygen deficiency measurement . 17
5 Measurement tasks . 18
5.1 General . 18
5.2 Exposure measurement (health monitoring) . 18
5.3 General gas detection (safety monitoring) . 19
6 Selection of equipment . 20
6.1 General . 20
6.2 Performance and electrical tests . 21
6.3 Indication range, measuring range and uncertainty of measurement . 21
6.4 Selectivity requirements . 22
6.5 The influence of environmental conditions . 23
6.6 The influence of electromagnetic interference . 23
6.7 Time of response and time of recovery . 24
6.8 Time to alarm . 25
6.9 Data logging . 25
6.10 Instruction manual . 26
7 Design and installation of fixed toxic gas detection equipment . 26
7.1 General . 26
7.2 Basic considerations for the installation of fixed systems . 27
7.3 Location of detection points . 28
7.4 Access for calibration and maintenance . 33
7.5 Additional considerations for sample lines . 33
7.6 Summary of considerations for the location of sensors or sampling points . 34
7.7 Installation of sensors . 35
7.8 Integrity and safety of fixed systems . 35
7.9 Commissioning . 36
7.10 Operating instructions, plans and records . 37
8 Operation of toxic gas detection equipment . 38
8.1 Alarm setting. 38
8.2 Operation of portable equipment . 39
8.3 Operation of transportable and fixed equipment . 43
8.4 Sample lines and sampling probes . 45
8.5 Accessories . 45
9 Maintenance and calibration . 46
9.1 General . 46

9.2 Sensor . 46
9.3 Flow systems of aspirated equipment. 46
9.4 Readout devices . 47
9.5 Alarms . 47
9.6 Maintenance . 47
9.7 Calibration . 48
9.8 Operation test . 49
9.9 Records . 50
10 Training . 50
10.1 General . 50
10.2 Operator training . 50
10.3 Maintenance and calibration training . 51
Annex A (informative) Commonly used measurement principles . 52
A.1 General . 52
A.2 Chemiluminescence . 52
A.3 Colorimetry . 53
A.4 Electrochemical . 54
A.5 Flame-ionization . 55
A.6 Gas chromatography . 55
A.7 Infrared photometry . 56
A.8 Ion mobility spectrometry . 57
A.9 Mass spectrometry . 58
A.10 Photo-ionization . 59
A.11 Semiconductor . 60
A.12 Ultra-violet/visible photometry . 61
Bibliography . 62

Figure 1 – Relationship between indication range and measuring range (See 6.3.1) . 11
Figure 2 – Example of zero uncertainty . 11
Figure 3 – Example of warm-up time in clean air . 12
Figure 4 – Relationship between indication range and measuring range . 22
Figure 5 – Gas response curves for test gas volume fractions of 40 ppm and 100 ppm . 24
Figure 6 – Time to alarm at 25 ppm set point for test gas volume fractions of 40 ppm
and 100 ppm . 25

Table A.1 – Chemiluminescence . 52
Table A.2 – Colorimetry . 53
Table A.3 – Electrochemical . 54
Table A.4 – Flame-ionization . 55
Table A.5 – Infrared photometry . 56
Table A.6 – Ion mobility spectrometry . 57
Table A.7 – Mass spectrometry . 58
Table A.8 – Photo-ionization (PID) . 59
Table A.9 – Semiconductor . 60
Table A.10 – Ultra-violet/visible photometry . 61

– 4 – IEC 62990-2:2021 © IEC 2021
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
WORKPLACE ATMOSPHERES –
Part 2: Gas detectors –
Selection, installation, use and maintenance
of detectors for toxic gases and vapours

FOREWORD
1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising
all national electrotechnical committees (IEC National Committees). The object of IEC is to promote international
co-operation on all questions concerning standardization in the electrical and electronic fields. To this end and
in addition to other activities, IEC publishes International Standards, Technical Specifications, Technical Reports,
Publicly Available
...

IEC 62990-2
Edition 1.0 2021-06
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
Workplace atmospheres –
Part 2: Gas detectors – Selection, installation, use and maintenance of detectors
for toxic gases and vapours
Atmosphères des lieux de travail –
Partie 2: Détecteurs de gaz – Sélection, installation, utilisation et maintenance
des détecteurs de gaz et de vapeurs toxiques

All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form
or by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from
either IEC or IEC's member National Committee in the country of the requester. If you have any questions about IEC
copyright or have an enquiry about obtaining additional rights to this publication, please contact the address below or
your local IEC member National Committee for further information.

Droits de reproduction réservés. Sauf indication contraire, aucune partie de cette publication ne peut être reproduite ni
utilisée sous quelque forme que ce soit et par aucun procédé, électronique ou mécanique, y compris la photocopie et
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CH-1211 Geneva 20 www.iec.ch
Switzerland
About the IEC
The International Electrotechnical Commission (IEC) is the leading global organization that prepares and publishes
International Standards for all electrical, electronic and related technologies.

About IEC publications
The technical content of IEC publications is kept under constant review by the IEC. Please make sure that you have the
latest edition, a corrigendum or an amendment might have been published.

IEC publications search - webstore.iec.ch/advsearchform IEC online collection - oc.iec.ch
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and French, with equivalent terms in 18 additional languages.
a month by email.
Also known as the International Electrotechnical Vocabulary

(IEV) online.
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IEC 62990-2
Edition 1.0 2021-06
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
Workplace atmospheres –
Part 2: Gas detectors – Selection, installation, use and maintenance of detectors

for toxic gases and vapours
Atmosphères des lieux de travail –

Partie 2: Détecteurs de gaz – Sélection, installation, utilisation et maintenance

des détecteurs de gaz et de vapeurs toxiques

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 29.260.20 ISBN 978-2-8322-1048-5

– 2 – IEC 62990-2:2021 © IEC 2021
CONTENTS
FOREWORD . 4
INTRODUCTION . 6
1 Scope . 7
2 Normative references . 7
3 Terms and definitions . 7
4 Properties and detection of toxic gases and vapours . 13
4.1 Properties and detection . 13
4.2 The difference between detecting gases and vapours . 14
4.3 Effects of water vapour on detection . 17
4.4 Effects of temperature and pressure on detection . 17
4.5 Effects of corrosion on detection . 17
4.6 Detection by oxygen deficiency measurement . 17
5 Measurement tasks . 18
5.1 General . 18
5.2 Exposure measurement (health monitoring) . 18
5.3 General gas detection (safety monitoring) . 19
6 Selection of equipment . 20
6.1 General . 20
6.2 Performance and electrical tests . 21
6.3 Indication range, measuring range and uncertainty of measurement . 21
6.4 Selectivity requirements . 22
6.5 The influence of environmental conditions . 23
6.6 The influence of electromagnetic interference . 23
6.7 Time of response and time of recovery . 24
6.8 Time to alarm . 25
6.9 Data logging . 25
6.10 Instruction manual . 26
7 Design and installation of fixed toxic gas detection equipment . 26
7.1 General . 26
7.2 Basic considerations for the installation of fixed systems . 27
7.3 Location of detection points . 28
7.4 Access for calibration and maintenance . 33
7.5 Additional considerations for sample lines . 33
7.6 Summary of considerations for the location of sensors or sampling points . 34
7.7 Installation of sensors . 35
7.8 Integrity and safety of fixed systems . 35
7.9 Commissioning . 36
7.10 Operating instructions, plans and records . 37
8 Operation of toxic gas detection equipment . 38
8.1 Alarm setting. 38
8.2 Operation of portable equipment . 39
8.3 Operation of transportable and fixed equipment . 43
8.4 Sample lines and sampling probes . 45
8.5 Accessories . 45
9 Maintenance and calibration . 46
9.1 General . 46

9.2 Sensor . 46
9.3 Flow systems of aspirated equipment. 46
9.4 Readout devices . 47
9.5 Alarms . 47
9.6 Maintenance . 47
9.7 Calibration . 48
9.8 Operation test . 49
9.9 Records . 50
10 Training . 50
10.1 General . 50
10.2 Operator training . 50
10.3 Maintenance and calibration training . 51
Annex A (informative) Commonly used measurement principles . 52
A.1 General . 52
A.2 Chemiluminescence . 52
A.3 Colorimetry . 53
A.4 Electrochemical . 54
A.5 Flame-ionization . 55
A.6 Gas chromatography . 55
A.7 Infrared photometry . 56
A.8 Ion mobility spectrometry . 57
A.9 Mass spectrometry . 58
A.10 Photo-ionization . 59
A.11 Semiconductor . 60
A.12 Ultra-violet/visible photometry . 61
Bibliography . 62

Figure 1 – Relationsh
...