IEC_60079-29-2-2015.pdf

IEC 60079-29-2 Edition 2.0 2015-03 INTERNATIONAL STANDARD Explosive atmospheres Part 29-2:Gas detectors Selection,installation,use and maintenance of detectors for flammable gases and oxygen IEC 60079-29-2:2015-03(en)THIS PUBLICATION IS COPYRIGHT PROTECTED Copyright 2015 IEC,Geneva,Switzerland 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 IECs 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.IEC Central Office Tel.:+41 22 919 02 11 3,rue de Varemb Fax:+41 22 919 03 00 CH-1211 Geneva 20 infoiec.ch Switzerland www.iec.ch 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 corrigenda or an amendment might have been published.IEC Catalogue-webstore.iec.ch/catalogue The stand-alone application for consulting the entire bibliographical information on IEC International Standards,Technical Specifications,Technical Reports and other documents.Available for PC,Mac OS,Android Tablets and iPad.IEC publications search-www.iec.ch/searchpub The advanced search enables to find IEC publications by a variety of criteria(reference number,text,technical committee,).It also gives information on projects,replaced and withdrawn publications.IEC Just Published-webstore.iec.ch/justpublished Stay up to date on all new IEC publications.Just Published details all new publications released.Available online and also once a month by email.Electropedia-www.electropedia.org The worlds leading online dictionary of electronic and electrical terms containing more than 30 000 terms and definitions in English and French,with equivalent terms in 15 additional languages.Also known as the International Electrotechnical Vocabulary(IEV)online.IEC Glossary-std.iec.ch/glossary More than 60 000 electrotechnical terminology entries in English and French extracted from the Terms and Definitions clause of IEC publications issued since 2002.Some entries have been collected from earlier publications of IEC TC 37,77,86 and CISPR.IEC Customer Service Centre-webstore.iec.ch/csc If you wish to give us your feedback on this publication or need further assistance,please contact the Customer Service Centre:csciec.ch.IEC 60079-29-2 Edition 2.0 2015-03 INTERNATIONAL STANDARD Explosive atmospheres Part 29-2:Gas detectors Selection,installation,use and maintenance of detectors for flammable gases and oxygen INTERNATIONAL ELECTROTECHNICAL COMMISSION ICS 29.260.20 ISBN 978-2-8322-2342-0 Registered trademark of the International Electrotechnical Commission Warning!Make sure that you obtained this publication from an authorized distributor.2 IEC 60079-29-2:2015 IEC 2015 CONTENTS FOREWORD.8 INTRODUCTION.11 1 Scope.13 2 Normative references.14 3 Terms and definitions.14 3.1 Gas properties and other physics.14 3.2 Types of equipment.16 3.3 Sensors and detectors.18 3.4 Supply of gas to instruments.19 3.5 Signals and alarms.19 3.6 Times,checks and equipment behaviour.20 3.7 Terms exclusive to open path equipment.21 4 Basic information on the properties,behaviour,gases and vapours,and specific applications of gas detection.23 4.1 Detecting gases and vapours.23 4.1.1 General.23 4.1.2 Safety when monitoring for flammable gases where personnel could be present.24 4.2 Some common properties of gases and vapours.25 4.3 The differences between detecting gases and vapours.26 4.3.1 General.26 4.3.2 Detection of gases.26 4.3.3 Detection of vapours.28 4.4 Oxygen deficiency.31 4.4.1 General.31 4.4.2 Chemical reaction of oxygen,with solid products.31 4.4.3 Chemical reaction of oxygen,with gaseous products.31 4.4.4 Dilution of the air by displacement by some other gas or vapour.32 4.5 Specific applications of gas detection.32 4.5.1 Gas detection as means of reducing risk of explosion.32 4.5.2 Gas free work permit.35 4.5.3 Monitoring of air inlets.36 4.6 Specific considerations for open path detection.36 5 Measuring principles.37 5.1 General.37 5.2 Catalytic sensors.39 5.2.1 General.39 5.2.2 Common applications.39 5.2.3 Limitations.39 5.2.4 Interferences.40 5.2.5 Poisoning.40 5.3 Thermal conductivity sensors.41 5.3.1 General.41 5.3.2 Common applications.41 5.3.3 Limitations.41 5.3.4 Interferences.41 IEC 60079-29-2:2015 IEC 2015 3 5.3.5 Poisoning.41 5.4 Infrared sensors.41 5.4.1 General.41 5.4.2 Common applications.42 5.4.3 Limitations.42 5.4.4 Interferences.42 5.4.5