title: Flammability of gas mixtures. Part 2: influence of inert gases.
abstract: Ternary systems, which contain flammable gas, inert gas and air, were studied in order to give the user an evaluation of the ISO 10156 calculation method for the flammability of gas mixtures. While in Part 1 of this article the fire potential of flammable gases was the focal point, the influence of inert gases on the flammability of gas mixtures was studied in Part 2. The inerting capacity of an inert gas is expressed by the dimensionless K value, the so-called "coefficient of nitrogen equivalency". The experimental determination of K values is demonstrated by using explosion diagrams. The objective of this study was to compare the estimated results, given by ISO 10156, with measurements of explosion ranges based on the German standard DIN 51649-1, given by CERN and CHEMSAFE. The comparison shows that ISO 10156, Table 1, supplies conservative K values, which can be regarded as safe in all cases. Nevertheless, in a number of cases ISO underestimates the inerting capacity, so that non-flammable gas mixtures are considered flammable.
authors.affiliation: Bundesanstalt für Materialforschung und -prüfung (BAM), Abt. Chemische Sicherheitstechnik, Unter den Eichen 87, D-12205 Berlin, Germany. maria.molnarne@bam.de
authors.forename: Maria
authors.initials: M
authors.lastname: Molnarne
authors.forename: Péter
authors.initials: P
authors.lastname: Mizsey
authors.forename: Volkmar
authors.initials: V
authors.lastname: Schröder
mesh_terms: D005107:Explosions / Q000517:prevention & control*; D005390:Fires / Q000517:prevention & control*; D017408:Guidelines as Topic; D008956:Models, Chemical; D005741:Noble Gases / Q000737:chemistry*
chemical_list: D005741:Noble Gases