Class A
Fire involving common combustion material and which can be extinguished by use of water or water solution in form of jet and spray e.g. materials include wood, wood based material, cloth, rubber, and certain plastics.
Class B
Fires involving flammable or combustion liquids, paints, varnishes, greases and similar products, either miscible or immiscible with water.
Extinguishing agents include water spray, foam, carbon dioxide and dry chemicals.
Class C
Fires that involve gases or liquid gases in the form of a liquid spillage or a liquid or gas leak. Gases include methane, butane etc.
Foam or dry chemicals may be used to control class c fires involving shallow liquid spills, water in the form of spray is used to cool the containers.
Class D
Fires that involve combustion metals, e.g. sodium, magnesium etc.
Extinguishing agents like water, CO2 and bicarbonates are infective and hazardous if used.
Powered graphite, powered talc, soda ash, limestone and dry sand are normally suitable for extinguishing class d type fires.
Electrical Fires
Electrical fire by itself does not constitute a class since any fire involving or started by electrical equipment will be a fire of class a, b, c or d.
In case of a fire involving electrical equipment, electricity supply to the respective equipment must be cut off and an extinguishing medium appropriate to what is burning must be used.
Type Of Detectors.
a. Heat detector that operates at a temperature at a pre determined temperature.
b. Heat detector that operate when rate of temperature rise of surrounding air exceeds a set limit.
c. Smoke detector that operates when smoke obscures a light beam falling on photoelectric cell.
d. Flame detect that react to light intensity, flicker of frequency or radiant energy.
