Selection of Fire Extinguishers

The various types of fire extinguishers specified in IS 2190 standard are of value but all are not equally effective on all types of fire. For this reason, the nature of contents of a building, the processes carried out therein and the types of fire which may occur shall be taken into consideration while selecting fire extinguishers. For all practical purposes, the basic types of fires can be grouped into following four classes:

Class A fires - Fires involving solid combustible materials of organic nature such as wood, paper, rubber, plastics, etc, where the cooling effect of water is essential for extinction of fires.
Class B fires - Fires involving flammable liquids or liquefiable solids or the like where a blanketing effect is essential.
Class C fires - Fires involving flammable gases under pressure including liquefied gases, where it is necessary to inhibit the burning gas at fast rate with an inert gas, powder or vaporising liquid for extinguishment.
Class D fires - Fires involving combustible metals, such as magnesium, aluminium, zinc, sodium, potassium, etc, when the burring metals are reactive to water and water containing agents and in certain cases carbon dioxide, halogenated hydrocarbons and ordinary dry powders. These fires require special media and techniques to extinguish.

Suitability of Portable Fire Extinguishers

The following extinguishers are generally more suitable for each type of fire. It may be noted, however, that this is for guidance only and does not include special cases.

Class A fires - Water, Foam and ABC dry power type fire extinguishers.
Class B fires - Foam, Dry powder, Clean agent and Carbon dioxide extinguishers.
Class C fires - Dry powder, Clean agent and Carbon dioxide extinguishers.
Class D fires - Extinguishers with special dry powder for metal fires.