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maritime DC & PPE Information Center

Halon Systems


Halon is a halogenated hydrocarbon that extinguishes a fire by chemically inhibiting the flame front. Halon 1301 and 1211 are the two types used onboard Navy ships, with 1301 being the most common. Halon 1301 systems may be installed in main engineering spaces, auxiliary machinery rooms, fuel pump rooms, ship service or emergency generator rooms, auxiliary boiler rooms, main propulsion or generator engine modules, helicopter Recovery, Assist, Securing and Traversing (RAST) machinery rooms, Tactical Towed Array Sonar (TACTAS) handling rooms and in spaces where flammable liquids are stored or issued. Halon systems use one or more cylinders containing Halon 1301 in a liquid form. Halon is to be used when portable extinguishers are ineffective and abandonment of the space is necessary. Each system is designed such that a single discharge of Halon 1301 will provide a concentration of 5 to 7 percent Halon 1301 by volume in air throughout the protected space. Sufficient Halon is required so that the concentration will remain at a minimum of 5 percent for 15 minutes.

Diagram of Halon System

Further information on Halon alternatives are available through http://greenfleet.dodlive.mil/environment/ships-submarines-and-aircraft-2/
Click on Navy's Shipboard Environmental Information Clearinghouse area and it will take you to NKOs restricted access site at

For more information see the index