The dry chemical powder fire extinguisher is one of the most versatile fire extinguishers available. This extinguisher is effective on Class A (Carbonaceous material such as paper), Class B (Flammable liquids) & Class C (Flammable gas) fires.
Therefore, dry powder is the ideal extinguishant where there is dangerous mixed fire risks. Only fire involving carbon disulphite and flammable metals such as magnesium and sodium should be avoided.
Dry chemical powder is a non conductor of electricity and is not dangerous to human beings or animals and it is a free flowing powder with a composition based on ammonium phosphate and sulphate with special additives to improve fluidity and storage.
Installation and maintenance of fire extinguishers to BS 5306 part 3.