Developments and prospective application of gas-solid hybrid composite powders in fire suppression

There are two types of mixed-phase systems with two fire suppression agents of powders and gases. The first type is halocarbon gelled dry chemicals, including monoammonium phosphate (MAP) powder thixotropically gelled with halon 1211 and 1301, sodium bicarbonate (BC) powder gelled with pentafluoropropane (HFC-125) and hexafluoropropane (HFC-236fa). The second type is halocarbon combined with dry chemicals, such as BC in conjunction with heptafluoropapane (FE-227ea), ammonia polyphosphate (APP) disseminated by HFC-236fa and MAP discharged with halon 2402. These mixed-phase fire suppressants would have better performance in suppressing fire to get shorter burning time with less agent mass but generating smaller amount of toxic products. However, there are technical problems while changing nitrogen to halocarbon. Physical design of the extinguisher has to change for the new mixed agents. The cost of installing two sets of fire suppression systems is high.