Fire-fighting foams are used in fire-fighting to extinguish flammable liquids (fire category B) and solids which liquefy in case of fire or heat exposure. Fire category B comprises three subgroups: u Flammable, water-immiscible liquids and liquefying, flammable chemicals u Flammable, water-miscible liquids u Thermoplastics, including rubber tyres Special Foams might also be used on fires of non-liquefying solids
(class A fires).