Testing of a Fine Water Mist Portable Fire Extinguisher in a Representative Spacecraft Atmosphere

Abstract

At recent ICES conferences, ADA Technologies introduced a prototype fine water mist fire extinguisher for use in next-generation manned spacecraft. This device is tolerant of the microgravity environment and uses only water and nitrogen as fire suppression agents. Its intended application extends to manned spacecraft and planetary habitats. This device employs Fine Water Mist (FWM) as the fire extinguishing technology in a single storage tank design for minimal mass and volume. The prototype employs a dual-fluid atomizer concept where the pressurant gas (nitrogen) also en hances the water droplet atomization process to generate a droplet size distribution in the optimum diameter range of 10 to 50 micrometers. The expanding gas plume carries the mist to the immediate vicinity of the fire where its large surface area promotes high heat tra nsfer rates in evaporating the mist droplets. The ADA project team recently validated t he performance of the prototype FWM extinguisher with two reduced-momentum nozzles in a chamber with a representative spacecraft atmosphere of 34% oxygen at 8 psia. Test fires at this condition were observed to be more intense than at Earth ambient conditions, but nevertheless the fires were successfully suppressed, albeit with longer extinct ion times. Parameters investigated in this test series to quantify fire suppression performanc e included extinguisher nozzle designs, multiple representative fires, spacecraft atmospher e, and fire-fighting technique. Results are being used to refine specifications for a flight-ha rdware rated portable fire extinguisher.