ABC powders are firefighting dry chemical powders for use against fires in fibrous materials such as paper, wood and textiles (Class A) as well as fires in flammable liquids (Class B) and flammable gases (Class C). ABC powders are mixes of finely ground solid chemicals i.e. ammonium sulphate and the active ingredient monoammonium phosphate (MAP). ABC powders are usually graded according to the content of MAP; ABC 30, ABC 40, ABC 50 and so on, where the number represent the % content of MAP. The more MAP the more efficient the powder will be.