Abstract: In response to the controversy over the explosion group classification of hydrogen containing gas mixtures and the conservative selection of flame arresters, the influence of hydrogen on the MESG of typical hydrocarbon gases such as methane, propane, and ethylene was experimentally studied. The results indicate that as the hydrogen content in the mixture increases, MESG gradually decreases. The rate of decrease of MESG with increasing hydrogen content varies among different hydrocarbons, and the effect of adding hydrogen on MESG of methane, propane, and ethylene gradually weakens. Suggestions for selecting flame arresters: For hydrogen-methane gas with a hydrogen content below 30%, IIA grade flame arresters can be selected; When the hydrogen content is equal to or greater than 30% but less than 60%, IIB3 level flame arresters can be selected; When the hydrogen content is greater than 60%, an IIC level flame arrester should be selected. For hydrogen-propane gas, when the hydrogen content is less than 60%, an IIB3 level flame arrester can be selected. When the hydrogen content reaches 60% or more, an IIC level flame arrester should be selected. For ethylene-hydrogen gas, it is recommended to use IIC grade flame arresters. A MESG prediction formula for hydrogen containing hydrocarbon gases was established, which is in good agreement with experimental results and outperforms existing calculation methods. It could be used to guide the classification of explosion levels for hydrogen containing hydrocarbon gases, as well as the selection of flame arresters and explosion-proof equipment.

Key words: hydrogen containing gas, MESG, selection of flame arresters, classification of explosion group