The equipment used in explosion -proof places is divided into: level I and II, III -level explosion -proof equipment. Among them, the use environment for the use of the explosion -proof equipment of II is under the coal mines, and the use environment of II explosion -proof equipment is all other explosive gas environments except coal mines and under wells. The environment applied to the type III explosion -proof equipment is an explosive dust environment except coal mines. Explosion-proof electric gourd explosion-proof levels are suitable for non-excavation working faces for explosion-proof coal mines and suitable for explosion-proof with type II explosion-proof. Place of gas mixture.