IS/IEC 60079-20-1 (2010): Electrical appratus for ...

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2 ! $ ' + - Satyanarayan Gangaram Pitroda Invent a New India Using Knowledge 0 1 ' 5 Jawaharlal Nehru Step Out From the Old to the New 1 + , 1 + Mazdoor Kisan Shakti Sangathan The Right to Information, The Right to Live ! > 0 B Bhart hari N ti atakam Knowledge is such a treasure which cannot be stolen Invent a New India Using Knowledge IS/IEC 60079-20-1 (2010): Electrical appratus for explosivegas atmospheres, Part 20: Material Characteristics for Gasand Vapour Classification, Section 1: Test Methods and Data[ETD 22: Electrical Apparatus for Explosive Atmosphere] BIS 2012 October 2012 Price Group 16B U R E A U O F I N D I A N S T A N D A R D SMANAK BHAVAN, 9 BAHADUR SHAH ZAFAR MARGNEW DELHI 110002 Hkkjrh; ekudfoLiQksVh i; 20 xSl ,oa ok"i osQ fy, lkexzh keZvuqHkkx 1 ijh{ i fr.}

3 K ,oa vkadM+sIndian StandardEXPLOSIVE ATMOSPHERESPART 20 MATERIAL CHARACTERISTICS FOR GAS AND VAPOUR CLASSIFICATIONS ection 1 Test Methods and DataICS 60079-20-1 : 2010[Superseding IS 7820 : 2004/IEC 60079-4 : 1975,IS 9570 : 1980, IS 9735 : 2003/IEC 60079-1-1 : 2002 andIS/IEC 60079 (Part 20) : 1996] Electrical Apparatus for Explosive Atmospheres Sectional Committee, ETD 22 NATIONAL FOREWORDThis Indian Standard (Part 20/Sec 1) which is identical with IEC 60079-20-1 : 2010 Explosiveatmospheres Part 20-1: Material characteristics for gas and vapour classification Test methodsand data issued by the International Electrotechnical Commission (IEC) was adopted by the Bureauof Indian Standards on the recommendation of the Electrical Apparatus for Explosive AtmospheresSectional Committee and approval of the Electrotechnical Division standard supersedes the following Indian Standards: International Standard Corresponding Indian StandardDegree of EquivalenceIEC 60079-11 Explosiveatmospheres Part 11 : Equipmentprotection by intrinsic safety i IEC 60079-14 Explosiveatmospheres Part 14.

4 Electricalinstallations design, selection anderectionIS/IEC 60079-11 : 2006 Explosiveatmospheres: Part 11 Equipmentprotection by intrinsic safety i IS 5571 : 2009 Guide for selectionand installation of electricalequipment in hazardous areas (otherthan mines)Identical toIEC 60079-11 : 2006 ModifiedOnly the English language text of the International Standard has been retained while adopting it inthis Indian Standard, and as such the page numbers given here are not the same as in the the purpose of deciding whether a particular requirement of this standard is complied with, thefinal value, observed or calculated, expressing the result of a test, shall be rounded off in accordancewith IS 2 : 1960 Rules for rounding off numerical values (revised).

5 The number of significant placesretained in the rounded off value should be the same as that of the specified value in this 7820 : 2004/IEC 60079-4 : 1975IS 9570 : 1980(Assistance drawn fromIEC 60079-12 : 1978)IS 9735 : 2003/IEC 60079-1-1 : 2002IS/IEC 60079 (Part 20) : 1996 Electrical apparatus for explosive gas atmospheres Methodof test for ignition temperatures (first revision)Classification of flammable gases or vapours with airaccording to their maximum experimental safe gaps andminimum igniting currentsElectrical apparatus for explosive gas atmospheres Flameproof enclosures d Method of test for ascertainmentof maximum experimental safe gap (first revision) Electrical apparatus for explosive gas atmospheres.

6 Part 20 Data for flammable gases and vapours relating to the use ofelectrical apparatusThe text of IEC Standard has been approved as suitable for publication as an Indian Standard withoutdeviations. Certain conventions are, however, not identical to those used in Indian is particularly drawn to the following:a) Wherever the words International Standard appear referring to this standard, they should beread as Indian Standard .b) Comma (,) has been used as a decimal marker while in Indian Standards, the current practiceis to use a point (.) as the decimal this adopted standard, references appear to certain International Standards for which IndianStandards also exist.

7 The corresponding Indian Standards, which are to be substituted in theirrespective places are listed below along with their degree of equivalence for the editions indicated: 6 60079-20-1 IEC:2010 EXPLOSIVE ATMOSPHERES Part 20-1: Material characteristics for gas and vapour classification Test methods and data 1 Scope This part of IEC 60079 provides guidance on classification of gases and vapours. It describes a test method intended for the measurement of the maximum experimental safe gaps (MESG) for gas- or vapour-air mixtures under normal conditions of temperature1 and pressure so as to permit the selection of an appropriate group of equipment.

8 The method does not take into account the possible effects of obstacles on the safe gaps2. This standard describes also a test method intended for use in the determination of the auto-ignition temperature of a chemically pure vapour or gas in air at atmospheric pressure. The tabulated values of chemical and engineering properties of substances are provided to assist engineers in their selection of equipment to be used in hazardous areas. It is hoped to publish further data from time to time, as the results of tests made in several countries become available. The scope of these data has been selected with particular reference to the use of equipment in hazardous areas, and notice has been taken of standard measurement methods.

9 NOTE 1 The data in this standard have been taken from a number of references which are given in the bibliography. NOTE 2 Some variations in the data may appear when references are compared, but usually the discrepancy is sufficiently small to be of no importance in the selection of equipment. 2 Normative references The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. IEC 60079-11, Explosive atmospheres Part 11: Equipment protection by intrinsic safety "i" IEC 60079-14, Explosive atmospheres Part 14: Electrical installations design, selection and erection 3 Terms and definitions For the purposes of this document, the following terms and definitions apply.

10 1 An exception is made for substances with vapour pressures which are too low to permit mixtures of the required concentrations to be prepared at normal ambient temperatures. For these substances, a temperature 5 K above that needed to give the necessary vapour pressure or 50 K above the flash point is used. 2 The design of the test apparatus for safe gap determination, other than that used for selecting the appropriate group of enclosure for a particular gas, may need to be different to the one described in this standard. For example, the volume of the enclosure, flange width, gas concentrations and the distance between the flanges and any external wall or obstruction may have to be varied.