MIL-E-24652, MILITARY SPECIFICATION: EXTINGUISHER, FIRE, AQUEOUS FILM FORMING FOAM, (AFFF), 2-1/2 GALLON (28 MAY 1985)., This specification covers the requirements for a 2-1/2 gallon fire extinguisher of the stored-pressure type. It is capable of generating a low expansion foam using AFFF concentrate and fresh water.