A portable device, for immediate and temporary use in putting out a fire: class A: used on fires involving ordinary combustible materials (such as wood, cloth, paper, rubber, and many plastics), which require the cooling effects of water or certain dry chemical coatings to retard combustion; class B: used on fires involving liquids, gases, greases, etc., extinguished most readily by excluding air or inhibiting the release of combustible vapors; class C: used on fires in live electrical equipment; class D: used on fires involving certain
combustible metals, such as magnesium, sodium, etc., requiring a heat-absorbing extinguishing medium not reactive with the burning metals.