IEC_61779-3-1998.pdf

INTERNATIONALIECSTANDARD61779-3First edition1998-04Electrical apparatus for the detectionand measurement of flammable gases Part 3:Performance requirements for group I apparatusindicating a volume fraction up to 100%methane in airAppareils lectriques de dtection et de mesuredes gaz combustibles Partie 3:Rgles de performance des appareils du groupe I pouvant indiquerune fraction volumique jusqu 100%de mthane dans lairReference numberIEC 61779-3:1998(E)LICENSED TO MECON Limited.-RANCHI/BANGALOREFOR INTERNAL USE AT THIS LOCATION ONLY,SUPPLIED BY BOOK SUPPLY BUREAU.NumberingAs from 1 January 1997 all IEC publications are issued with a designation in the60000 series.Consolidated publicationsConsolidated versions of some IEC publications including amendments areavailable.For example,edition numbers 1.0,1.1 and 1.2 refer,respectively,to thebase publication,the base publication incorporating amendment 1 and the basepublication incorporating amendments 1 and 2.Validity of this publicationThe technical content of IEC publications is kept under constant review by the IEC,thus ensuring that the content reflects current technology.Information relating to the date of the reconfirmation of the publication is availablein the IEC catalogue.Information on the subjects under consideration and work in progress undertaken bythe technical committee which has prepared this publication,as well as the list ofpublications issued,is to be found at the following IEC sources:IEC web site*Catalogue of IEC publicationsPublished yearly with regular updates(On-line catalogue)*IEC BulletinAvailable both at the IEC web site*and as a printed periodicalTerminology,graphical and lettersymbolsFor general terminology,readers are referred to IEC 60050:InternationalElectrotechnical Vocabulary(IEV).For graphical symbols,and letter symbols and signs approved by the IEC forgeneral use,readers are referred to publications IEC 60027:Letter symbols to beused in electrical technology,IEC 60417:Graphical symbols for use on equipment.Index,survey and compilation of the single sheets and IEC 60617:Graphical symbolsfor diagrams.*See web site address on title page.LICENSED TO MECON Limited.-RANCHI/BANGALOREFOR INTERNAL USE AT THIS LOCATION ONLY,SUPPLIED BY BOOK SUPPLY BUREAU.INTERNATIONALIECSTANDARD61779-3First edition1998-04Electrical apparatus for the detectionand measurement of flammable gases Part 3:Performance requirements for group I apparatusindicating a volume fraction up to 100%methane in airAppareils lectriques de dtection et de mesuredes gaz combustibles Partie 3:Rgles de performance des appareils du groupe I pouvant indiquerune fraction volumique jusqu 100%de mthane dans lair Commission Electrotechnique Internationale International Electrotechnical CommissionPour prix,voir catalogue en vigueurFor price,see current catalogue IEC 1998 Copyright-all rights reservedNo part of this publication may be reproduced or utilized in any form or by any means,electronic ormechanical,including photocopying and microfilm,without permission in writing from the publisher.International Electrotechnical Commission3,rue de Varemb Geneva,SwitzerlandTelefax:+41 22 919 0300e-mail:inmailiec.ch IEC web site http:/www.iec.chPRICE CODEGLICENSED TO MECON Limited.-RANCHI/BANGALOREFOR INTERNAL USE AT THIS LOCATION ONLY,SUPPLIED BY BOOK SUPPLY BUREAU.2 61779-3 IEC:1998(E)INTERNATIONAL ELECTROTECHNICAL COMMISSION_ELECTRICAL APPARATUS FOR THE DETECTIONAND MEASUREMENT OF FLAMMABLE GASES Part 3:Performance requirements for group I apparatusindicating a volume fraction up to 100%methane in airFOREWORD1)The IEC(International Electrotechnical Commission)is a worldwide organization for standardization comprisingall national electrotechnical committees(IEC National Committees).The object of the IEC is to promoteinternational co-operation on all questions concerning standardization in the electrical and electronic fields.Tothis end and in addition to other activities,the IEC publishes International Standards.Their preparation isentrusted to technical committees;any IEC National Committee interested in the subject dealt with mayparticipate in this preparatory work.International,governmental and non-governmental organizations liaisingwith the IEC also participate in this preparation.The IEC collaborates closely with the International Organizationfor Standardization(ISO)in accordance with conditions determined by agreement between the twoorganizations.2)The formal decisions or agreements of the IEC on technical matters express,as nearly as possible,aninternational consensus of opinion on the relevant subjects since each technical committee has representationfrom all interested National Committees.3)The documents produced have the form of recommendations for international use and are published in the formof standards,technical reports or guides and they are accepted by the National Committees in that sense.4)In order to promote international unification,IEC National Committees undertake to app