Multipurpose overhead compressed-air foam system and its fire suppression Performance

The paper describes a newly-developed compressed-air foam (CAF) system, based on an overhead fixed-pipe installation, and presents results showing its fire suppression performance. The CAF system generates foams by injecting compressed air into the flowing foam solution. The resulting foam is characterized by excellent fire-mitigation properties. This is because compressed-air foams, at the expansion ratios of between 1:4 tc 1:10, consist of very small and uniform-in-size air bubbles. The system needs little water to operate and is able to provide effective protection against Class A and B fires. The system's performance was compared to the performance of water mist and sprinkler-based installations. The experiments confirmed that the CAF system is effective in suppressing Class A and B fires. For the scenarios evaluated, the compressed-air system generated foams with sufficient momentum to penetrate the fire plume and to reach the fuel surface. The experimental results indicate that, in an open space, the foam system performs much better than water mist in extinguishing wood crib and flammable liquid pool fires. In an enclosed space, both water mist and compressed-air foam perform equally well against flammable liquid fires. The suppression performance of the CAF system on large wood crib fires was much better than a sprinkler system.