Why flame arrester is used on board ?

One of the greatest dangers involved with the transport or storage of flammable liquids or gases is that ignition of the flammable vapour may occur, resulting in fire or worse, an explosion.

Whenever a flammable gas or vapour is mixed with air/oxygen, there is the potential for an explosion. Accidental ignition of the flammable mixture will result in a flame that will travel through the unburnt mixture until the fuel is consumed by the reaction. In an enclosed space, such as a vessel or a pipe, the significant temperature increase of the mixture caused by the combustion process will lead to a rapid increase in the volume of the gas mixture. The resulting increase in pressure will induce turbulent effects which will further accelerate the flame front.

Above mentioned reason leads to introduction of  the subject of flame arresters, and the principles and concepts behind their specification and use.