Halon Replacement for Aviation Systems

The Montreal protocol banning halon production after 1995 has motivated the Air Force to actively seek replacements for halocarbon fire extinguishers. Currently proposed drop-in replacements such as HCFC's and CF3I have carbon-halogen bonds and are thus vulnerable to the same environmental concerns as is CF3Br (Halon 1301). While bromine atoms are very effective at catalytically poisoning the chain reactions of combustion, it is not essential to deliver Br to a flame as a halocarbon. A Phase I SBIR program is proposed to explore halon substitutes based on labile Br in a proprietary material that meets Air Force requirements for thermal stability, toxicity, and extinguishing capability per unit mass and volume. The proposed species is water soluble. Both it and its combustion products are unstable against tropospheric oxidation and thus have neither ozone depletion potential nor global warming potential. Theoretical analyses will include computational fluid dynamics and thermochemical kinetics at an appropriate level for wide area and aircraft engine fires. The thermal and oxidative decomposition products of the material will be calculated using quantum electronic structure methods and will be compared with pyrolytic and oxidation experiments. An engineering experiment will add calibrated flows of existing and proposed extinguishing materials to a 100,000 Btu/hr turbine fuel flame. The flame's response will be diagnosed by optical and infrared emission to rank existing and new extinguishing materials. The ranking developed from the small-scale experiment will be compared to the results of more elaborate, published studies of current extinguishers, including Halon 1301, hydro-fluorocarbons, trifluoromethyliodide, water and sodium bicarbonate. OPTION: $19,991