Tuesday, May 15, 2012

Why cannot a petrol fire be extinguished by water?

Petrol as a liquid is less dense than water. As water is thrown onto the petrol, the petrol floats on top of the water and continues to vapourise. It is the vapour which burns, slightly above the surface of the petrol. Also, if small quantity of water is poured over burning petrol, the existing temperature is so high, that the water poured on the fire evaporates even before it can extinguish the fire.