The ZHQ-1 gravel flame arrester produced and sold by Huadian Pump and Valve Company is a safety device used to prevent the spread of hydrogen flame to the outside. It consists of a solid material (flame retardant element) with many small channels or gaps that can pass through gas. The gap or passage of the flame retardant element is required to be as small as possible, so when the flame enters the flame arrester, the flame retardant element is divided into many small flame streams, and the flame flow is quenched due to heat transfer (gas is cooled) and the wall effect.