A twin-agent fire extinguishing system (TAFES), also commonly referred to as a twin-agent unit (TAU), incorporates the benefits of dry chemical and foam (
AFFF or
CAFS) fire extinguishing agents.
It is most commonly used for
AR-FF operations and in industrial areas with high class B hazards.
The dry chemical, usually
Purple-K Purple-K, also known as PKP, is a dry-chemical fire suppression agent used in some dry chemical fire extinguishers. It is the second most effective dry chemical in fighting class B (flammable liquid) fires after Monnex (potassium allophanate), and ...
(and in some applications
ABC Dry Chemical), knocks down the fire rapidly, while the foam secures the hazard by laying a vapor-suppressing blanket on the fuel and helping to cool the fuel in skin fires.
In pressurized gas fires the foam is applied to extinguish the fuel fires around the blowout and cool heated metal. The Purple-K stream is then discharged into the blowout to "snuff" it out.
These systems can be mounted on vehicles,
skid mount
A Skid mount is a popular method of distributing and storing machinery and usually-stationary equipment for the military and industry on its own or with other units as part of a modular system ( modular process skid). The machinery at point of ma ...
s or installed as permanent stations. Application is from twin hose lines connected together at the nozzle, one flows the dry chemical agent and the other foam. Twin agent systems are also used in fixed nozzles of vehicles (i.e. AR-FF vehicles) or ground mounted monitors in high hazard locations in facilities storing or producing flammable liquids. See
Airport crash tender
Dry chemical tank capacities range from . AFFF solution capacity ranges from . Dry chemical flow rates vary from per second and per minute for the foam for handline application.
References
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Sources
*James H. Meidl: "Flammable Hazardous Materials", Glencoe Press Fire Science Series, 1970.
Firefighting equipment
Fire suppression
Aircraft rescue and firefighting