Electronic Space Fire Protection: False Deck Mockup Fire Testing of Nanomist Systems

摘要

Reduced manned Naval vessels require automated fire suppression systems to compensate for the reduced size of damage control parties. Fine water mist systems are attractive from a total ship protection standpoint. However, the interaction between the applied mist and the compartment boundaries and obstructions in the sub-floor causes excessive mist loss because of flow obstructions NanoMist Systems, LLC, has a patented technology (NanoMist) that generates and discharges ultra fine mist (UFM) at ambient pressure with average drop sizes smaller than 10 microns. This drop size is significantly lower than that generated in conventional water mist systems that utilize high fluid pressure or shearing air flows to generate the water mist. Mist characterization testing on mist samples withdrawn from the back of the mock-up revealed an average drop size, Dv50, of 7 microns. The mist behaves like a dense gas in terms of transport and dispersion inside a cluttered volume. In the constant search for a nearly clean-gas-like water mist system, NanoMist ultrafine water mist was investigated for fire suppression in electronic space fire suppression in a sub-floor mockup using telltale flames behind obstruction caused by a baffle. The electronic exposure test was conducted using a modem card. The ultrafine mist (UFM) extinguished the telltale fire with a 0.053 LPM/m2 water application flux in approximately 3 minutes. The lower water application flux tested, 0.037 LPM/m2 after 8.5 minutes which corresponded to 2.6 air changes. The polypropylene array fire was more readily extinguished by the NanoMist tested. The external communication modems exposed to the generated water mists were able to continue operating for at least 7 minutes after mister actuation. The ultra fine water mist showed significant promise in this application. The small drop size and high initial mist water concentration enabled the generated mist to extinguish the test fires located behind a baffle spanning a third of the enclosure width and the entire enclosure height.