OS International Standard 6184/2 INTERNATIONAL ORGANIZATION FOR STANDARDIZATIONMEKAYHAPOAHAA OPTAHW3ALMA NO CTAHAAPTW3AUMWORGANISATION INTERNATIONALE DENORMALISATION Explosion protection systems Part 2: Determination of explosion indices of combustible gases in air Systemes de protection contre les explosions - Partie 2: Détermination des indices d'explosion des gaz combustibles dans I'air First edition - 1985-11-15 ISO 6184/2-1985 (E) UDC 614.835 Ref. No. ISO 6184/2-1985 (E) Descriptors : explosion proofing, burning gases, tests, explosion index. Price based on 5 pages Foreword ISo (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies). The work of preparing International Standards is normally carried out through Iso technical committees. Each member body interested in a subject for which a technical committee has been established has the right to be represented on that committee. International organizations, govern- mental and non-governmental, in liaison with iso, also take part in the work. Draft International Standards adopted by the technical committees are circulated to the member bodies for approval before their acceptance as International Standards by the Iso Council. They are approved in accordance with IsO procedures requiring at least 75 % approval by the member bodies voting. International Standard ISO 6184/2 was prepared by Technical Committee ISO/TC 21, Equipment for fire protection and fire fighting. Users should note that all International Standards undergo revision from time to time and that any reference made herein to any other International Standard implies its latestedition,unlessotherwisestated @ International Organization for Standardization, 1985 Printed in Switzerland INTERNATIONAL STANDARD ISO 6184/2-1985 (E) Explosion protection systems Part 2: Determination of explosion indices of combustible gases in air 0 Introduction plosion hazards should be recognized. In particular, the degree of turbulence can influence the hazard significantly. In practice, 0.1 The assessment of measures required to provide protec- the link between a given degree of turbulence and a specific tion against explosionhazards involving combustiblegas/air type of hazard is the responsibility of specialists in the fields of mixturesrequirespriordeterminationofthepotentialexplosion explosionsand explosionprotection. severityof suchmixtures,bythe measurement of explosion indices. Conversely, the measurement of the effectiveness and Two extremes of turbulence commonly encountered in in- performance of explosion protection systems requires that they dustrial plants are: should be tested against explosions of known severity. a) quiescent conditions prevailing in storage vessels; The severity of a combustible gas explosion is a function of the b) high turbulence conditions prevailing in the region of an following : extractionfan. a) the chemical properties of the combustible gas; It should be realized that turbulence can arise in two ways : b) the concentration of the combustible gas in the gas/air a) turbulence intrinsic to the plant, under normal mixture; operatingconditions,asaconsequenceofperturbationsto the air-flow; c) the homogeneity and turbulence of the combustible b) turbulence induced by obstructions within an instal- gas/airmixture; lation on a gas which expands as the result of an explosion. d) the type, energy, and location of the ignition source; e) the geometry of the container; f) the temperature, and pressure of the combustible 1 Scope gas/air mixture. This part of IS0 6184 specifies a method for the determination 0.2 This part of is0 6184 is one of a series deaing with ex- of the expiosion indices of combustibie gases with air in an plosionprotectionsystems.Theotherpartsareasfollows: enclosed space.It givesthecriteriabywhich resultsobtained using other test procedures can be correlated to yield explosion Part 1: Determination of explosion indice