A new safety-valve construction was developed and tested by studying combined dynamic and static loads between powered supports and surrounding rocks. The gasair mixture explosion conditions were modeled to test the dynamic load. Explosion properties of the gas-air mixtures (including maximum explosion pressure, maximum rise rate of explosion pressure, explosion rime, deflagration index) were investigated experimentally at room temperature in a cylindrical chamber with top-center ignition. The results showed that the maximum explosion pressure, maximum rate of pressure rise, and deflagration index were linearly correlated to the initial pressure. On the other hand, the explosion time depended mainly on the ratio of gases and only in a limited range on the initial pressure. The experimentally measured explosion properties of LPGair mixtures could be used in practice to study safe operation of safety valves.