Advances in Development of a Fine Water Mist Portable Fire Extinguisher

ADA Technologies, Inc. has designed and built a microgravity-tolerant portable fire extinguisher prototype for use in manned spacecraft and planetary habitats. This device employs Fine Water Mist (FWM) as the fire extinguishing agent, and is refillable from standard stores on long-duration missions. The design uses a single storage tank for minimal mass and volume. The prototype employs a dual-fluid atomizer concept where the pressurant gas (nitrogen) also enhances the water atomization process to generate a droplet size distribution in the optimum diameter range of 10 to 50 micrometers. The expanding discharge gas plume carries the mist to the immediate vicinity of the fire where its extensive surface area promotes high heat transfer rates. A series of 80 fire suppression tests was recently completed to evaluate design options for the hardware and validate performance on three representative fire scenarios. Test fires were conducted in two different spaces representative of the Orion Crew Exploration Vehicle (CEV) environment. The test matrix explored the effects of charge pressure and gas-to-liquid ratio on the amount of agent required to extinguish test fires. In the optimum configuration for the prototype, fires were extinguished with an average quantity of agent of well under one pound.