IEC_61779-4-1998.pdf

INTERNATIONALIECSTANDARD61779-4First edition1998-04Electrical apparatus for the detectionand measurement of flammable gases Part 4:Performance requirements for group II apparatusindicating a volume fraction up to 100%lower explosive limitAppareils lectriques de dtection et de mesuredes gaz combustibles Partie 4:Rgles de performance des appareils du groupe II pouvant indiquerune fraction volumique jusqu 100%de la limite infrieuredexplosivitReference numberIEC 61779-4:1998(E)Copyright International Electrotechnical Commission Provided by IHS under license with IECNot for ResaleNo reproduction or networking permitted without license from IHS-,-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.Copyright International Electrotechnical Commission Provided by IHS under license with IECNot for ResaleNo reproduction or networking permitted without license from IHS-,-INTERNATIONALIECSTANDARD61779-4First edition1998-04Electrical apparatus for the detectionand measurement of flammable gases Part 4:Performance requirements for group II apparatusindicating a volume fraction up to 100%lower explosive limitAppareils lectriques de dtection et de mesuredes gaz combustibles Partie 4:Rgles de performance des appareils du groupe II pouvant indiquerune fraction volumique jusqu 100%de la limite infrieuredexplosivit Commission Electrotechnique Internationale International Electrotechnical CommissionPour prix,voir catalogue en vigueurFor price,see current catalogue IEC 1998 Droits de reproduction rservs Copyright-all rights reservedAucune partie de cette publication ne peut tre reproduite niutilise sous quelque forme que ce soit et par aucunprocd,lectronique ou mcanique,y compris la photo-copie et les microfilms,sans laccord crit de lditeur.No part of this publication may be reproduced or utilized inany form or by any means,electronic or mechanical,including photocopying and microfilm,without permission inwriting from the publisher.International Electrotechnical Commission3,rue de Varemb Geneva,SwitzerlandTelefax:+41 22 919 0300e-mail:inmailiec.ch IEC web site http:/www.iec.chCODE PRIXPRICE CODEDCopyright International Electrotechnical Commission Provided by IHS under license with IECNot for ResaleNo reproduction or networking permitted without license from IHS-,-2 61779-4 IEC:1998(E)INTERNATIONAL ELECTROTECHNICAL COMMISSION_ELECTRICAL APPARATUS FOR THE DETECTIONAND MEASUREMENT OF FLAMMABLE GASES Part 4:Performance requirements for group II apparatusindicating a volume fraction up to 100%lower explosive limitFOREWORD1)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 exp