IEC_60079-8-1969_scan.pdf

束PeserveCOMMISSION ELECTROTECHNIQUE INTERNATIONALE(ffiliea Organisation Internationale de Normalisation-ISO)RECOMMANDATION DE LA C EIINTER NATIONAL ELECTROTECH NICAL COM MISSION(affiliated to the nterational Organization for Standardization-)IE C RECOMMENDATIONPublication 79-8Premiere edition-First edition1969Materiel electrique pour atmospheres explosivesHuitieme partie:Classification des temperatures maximales de surfaceElectrical apparatus for explosive gas atmospheresPart 8:Classification of maximum surface temperaturesU成E0,STAND RES ANAFY SFCTONNA0i.八FGY ADIHORITYDroits de reproduction reserves-Copyright-all rights reservedBureau Central de la Commission Electrotechnique Internationale1.rue de VarembeGeneve,SuisseIECvol.4-7一ELECTRICAL APPARATUS FOR EXPLOSIVE GAS ATMOSPHERESPart 8:Classification of maximum surface temperaturesScopeThis Recommendation establishes six preferred maximum surface temperatures for electricalapparatus for use in explosive atmospheres.A system of marking is specified.DefinitionFor the purpose of this Recommendation,the following definition applies.2.1 Maximum surface temperatureThe highest temperature attained under practical conditions of operation within the rating ofthe apparatus(and recognized overloads,if any,associated therewith)by any part of any surface,the exposure of which to an explosive atmosphere may involve a risk.Note.-For flameproof apparatus,the surface to be considered is the external surface.For other types of appa-ratus,internal surfaces are equally important,if the explosive atmosphere has access to them.ClassificationThe classification is as shown in Table I.TABLE I.ClassificationClassMaximum surface temperatureCTI450T2300&200135Ts10085Note.-In declaring the maximum surface temperature of any particular piece of apparatus,regard should be paidto the value of ambient temperature on which the specification for the apparatus is based.4.Marking4.1Apparatus designed to operate at a maximum surface temperature not greater than one of thepreferred maximum surface temperatures given in Table I shall be clearly marked with the symbolindicating the class,or with the preferred maximum surface temperature of the class,or both.4.2 It is recognized that it may be expedient to design apparatus for a particular application in cir-cumstances such that it would be undesirable for economic reasons to classify the equipmentaccording to the next higher preferred maximum surface temperature.In that event,the appa-ratus shall be clearly marked with the maximum surface temperature at which it is designed tooperate and may,in addition,be marked with the appropriate classification symbol given in Table I.Notes 1.-To avoid confusion between ordinary apparatus(Sub-clause 4.1)and special apparatus(Sub-clause 4.2),it is recommiended that when the marking includes both a non-preferred temperature and a classificationsymbol,the symbol should follow the temperature and be put within brackets.For example:-Ordinary apparatus:TI 450 C.-Special apparatus:350 C(T1).2.-Apparatus designed for a maximum surface temperature greater than 450 C should be marked withthe temperature only.For example:600 C.