Future of Aqueous Film Forming Foam (AFFF): Performance Parameters and Requirements.

摘要

Aqueous film forming foam (AFFF) is a highly efficient type of fire suppressant agent, used by itself to attack flammable liquid pool fires, and in conjunction with Halon 1301 to attack fires in Navy vessel machinery spaces. Gaseous halon replacements for machinery spaces will likewise operate in conjunction with AFFF systems. Also, portable AFFF extinguishers have been manufactured as alternatives to handheld Halon extinguishers for both conventional and marine applications. AFFF used by the U. S. military must meet the requirements set forth in Military Specification MIL-F-24385F, which is under the control of the Naval Sea Systems Command, Code 05P9. The Naval Research Laboratory is the designated institution for certification evaluation for the Department of Defense (DoD) AFFF Qualifying Products List (QPL). AFFF is used in the U.S. military, and in most civilian applications worldwide, as either a 3% or a 6% concentrate. The numbers refer to the percentage of the foam concentrate mixed with either fresh or sea water by a proportioning nozzle. The foam forms spontaneously upon ejection of the concentrate/water mix from the nozzle. An aspirating nozzle is not needed nor used. The AFFF coats a pool of hydrocarbon fuel with a layer of foam, which acts as a thermal and evaporation barrier to inhibit and eventually extinguish combustion. The film-forming characteristic refers to the fact that, even after the foam has dissipated, the aqueous layer formed from the water/concentrate mixture can coat a liquid hydrocarbon surface. The MilSpec AFFF formulations are effective against a wide variety of liquid hydrocarbon fire threats. Special formulations exist for use against alcohol and other water-miscible fuels.