The conditions of the gas explosion
Gas generator is the power generation by using the principle of gas explosion, gas explosion need to satisfy the following three conditions: 1, the concentration of gas. The concentration of the gas explosion limit refers to the mixture of gas and air and the gas volume concentration. When the gas concentration up to nine. 5%, the gas can react with air oxygen security in theory, so as to release most of the quantity of heat, so the strength of the blast; When the gas concentration is lower than 5%, due to chemical reaction gas is less, can't form the heat accumulation, so can't explode, can only burn; When the gas concentration is higher than 16%, caused by a lack of oxygen in the air, doesn't satisfy the need of oxygen reaction all, there is only part of the gas react with oxygen, the generated heat is absorbed by excess gas and ambient medium cooling, so also will not be able to explode. 2, sufficient oxygen. Concentration of oxygen in gas and air mixed gas must be greater than 12%, the explosion reaction can't continue. Within the closed area, goaf coal mine and other place such as crack, due to oxygen consumption or no oxygen supply conditions, may the oxygen concentration below 12%; Other roadway, workplace and so on oxygen content shall not be less than 20%, according to the rules are not usually present oxygen concentration less than 12% of the time, because in some cases, staff will be choked to death in a short time. 3, enough energy source. Ignition source that causes of gas explosion is three conditions: ( 1) Temperature is not lower than 650 degrees. （ 2) Energy is greater than zero. 28mJ. ( 3) The duration of the induction period is greater than the explosion. These three conditions are usually very easy to meet, such as flame, coal spontaneous combustion, strike sparks, edm, etc. For some unavoidable in the process of coal mining, the fire sometimes requires special technology, make its can't meet the gas ignition conditions. Millisecond detonator used in the underground blasting, for example, when the flames, and other temperature of 2000 degrees, but the last time is very short, less than the explosion induction period, so as not to cause gas explosion.