Fire Extinguishing Agents for Protection of Occupied Spaces in Military Ground Vehicles
ARMY TANK AUTOMOTIVE RESEARCH DEVELOPMENT AND ENGINEERING CENTER WARREN MI GROUND SYSTEMS SURVIVABILITY DIV
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Historically the US Army USA used Halon 1301 bromotrifluoromethane, a chemical with high Ozone Depletion Potential ODP, to protect the crews of armored vehicles from the effects of peacetime and combat fires. Since the phase-out of Halon production the USA has directed that zero ODP materials be used wherever possible. Subsequently, major new vehicle platforms have been deployed with Automatic Fire Extinguishing Systems AFES that rely on HFC-227BC, a zero-ODP-agent blend of HFC-227ea heptafluoropropane and sodium-bicarbonate-based dry chemical. Unfortunately, hydrofluorocarbons HFCs generally have high Global Warming Potential GWP - thousands of times that of carbon dioxide on a weight basis. Hence, as part of a larger effort to reduce its carbon footprint, USA Program Managers have asked that more environmentally friendly fire extinguishing agents be evaluated as part of ongoing vehicle modernization efforts. Several agents are being investigated, including FK-5-1-12, water with additives, and dry chemicals. This report describes the findings of more than 150 live-fire tests using nine agents and four extinguisher technologies. The basic conclusion is that no alternate agent can yet be considered to be a drop-in replacement for Halon 1301 or HFC-227BC for this application. However, a blend of Halon 1301 and dry chemical has been found to be about twice as effective as Halon 1301 alone. Thus, pending confirmation tests on vehicles, it may be feasible to use less Halon in legacy systems without compromising fire protection performance.
- Inorganic Chemistry
- Safety Engineering