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Automatic Fire Extinguishing Systems (AFES) Obscuration Testing

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[Technical Report, Final Report]

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Since the cease of production of high ozone depleting substances such as halon 1301bromotrifluoromethane, the US Army USA has relied on hydrofluorocarbon HFC extinguishing agents for many of its fire suppression applications. However, production of HFCs is being phased down due to their high global warming potentials GWP. Therefore, the Army initiated a research program to evaluate potential environmentally-friendly, low-GWP chemicals as candidate fire extinguishing agents for use in automatic fire extinguishing systems AFES that protect the crew of Army vehicles against fire and explosions caused by combat threats. The current effort is a continuation of research conducted for ground and aviation weapon systems. This report summarizes obscuration effects of a potential alternative agent. Specifically, we present obscuration measurements KSA, a proprietary finely ground sodium bicarbonate dry chemical, compared to legacy fire extinguishing gaseous agents halon 1301 and HFC227-BC heptafluoropropane mixed with sodium bicarbonate dry chemical powder. KSA was developed as a potential replacement for halon 1301 in civil aviation fire protection systems. We observed prolonged obscuration in the crew compartment after a discharge of KSA, significantly longer than obscuration due to legacy agents. There are currently no Army criteria for obscuration effects in combat vehicle crew compartments. Our results indicate that such criteria may be needed to evaluate more environmentally friendly fire protection agents.


Subject Categories:

  • Safety Engineering

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[A, Approved For Public Release]