生活中我们有这样的常识，在一个密闭的空间中当可燃气体达到一定浓度时，遇明火会立即发生爆炸，即剧烈燃烧瞬间蔓延至整个空间。而爆炸极限指在空气中，可发生爆炸的气体比例区间-In life we have such common sense, in a confined space when the combustible gas reaches a certain concentration, the event of fire will immediately exploded, that is,