The
Foam
Foam extinguisher, with aqueous flim forming addictive (AFFF), offers improved fire extinguishing abilities over water based extinguisher . The foams forms an aqueous flim which helps to prevent the release of fuel vapours while the foam blanket (from which the flim forming liquid drains) excludes oxygen from the fuel surface, extinguishing the fire and preventing re-ignition. The water content of the foam provides a cooling effect. The flim forming liquid, although heavier, floats on the surface of the fuel, due to it's surface tension
Effective on B class hydrocarbon fuel fires such as oil , petroleum, aviation fuel, and is paticularly suitable where fast fire knockdown is essential. It is compatible with all dry powders. It's excellent wetting characteristics make it useful in combating Class A fire as well
Water
The most commonly used type of fire extinguishant for Class A fires involving carbonaceous materials such as wood, textiles by cooling the fire and removing the heat needed for combustion