Explanation

Combustible substances (combustible gas, vapor and dust) and air (or oxygen) must be evenly mixed within a certain concentration range to form a premixed gas. explosion will occur only when they meet the fire source. This concentration range is called explosion limit, or explosion concentration limit. The explosion limit of flammability mixture can be divided into explosion (fire) lower limit and explosion (fire) upper limit: explosion lower limit and explosion upper limit respectively. The upper limit refers to the high concentration of flammability mixture that can cause explosion. When it is higher than the upper limit of explosion, the air is insufficient, so the flame cannot spread, neither explosion nor fire. The lower limit refers to the low concentration of flammability mixture that can cause explosion. Due to the insufficient concentration of combustibles and the cooling effect of excess air, the spread of flame is prevented. Therefore, when it is lower than the lower limit of explosion, neither explosion nor fire occurs. In daily life and chemical production, in order to reduce the explosion concentration limit, inert gas or other nonflammable gas can be added to reduce the concentration, or the explosive gas can be removed by scrubber and adsorption before the gas is discharged..

Classification