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Advanced Fire Suppression Technology for Aircraft: Findings of the Next Generation Fire Suppression Technology Program.


pdf icon Advanced Fire Suppression Technology for Aircraft: Findings of the Next Generation Fire Suppression Technology Program. (42 K)
Gann, R. G.

Volume 2;

Interflam 2007. (Interflam '07). International Interflam Conference, 11th Proceedings. Volume 2. September 3-5, 2007, London, England, 1647-1652 pp, 2007.

Keywords:

transportation; tunnels; fire suppression; aircraft fires; in-flight fires; halon alternatives; halon 1301; nacelle engines; dispersions; nacelle fires; evaluation; fire tests; air supply; costs; flame inhibition; extinguishment

Abstract:

In 1974, it was discovered that certain fully halogenated chemicals (chlorofluorocarbons, CFCs) could result in major changes in life on this planet. These long-lived compounds would rise to the stratosphere, where they were photodissociated by ultraviolet (UV) light. The chlorine atoms catalyzed the conversion of ozone, which absorbs solar UV light and protects the earth's flora and fauna from excessive UV radiation, to ordinary oxygen, which provides no such protection. The nations of the world reached agreement to protect the environment. In the process, it was realized that some brominated compounds were potentially more dangerous than the CFCs, and the firefighting halons were named explicitly. Their production was curtailed sharply in amendments to the U.S. Clean Air Act of 1990. As of January 1, 1994, halon 1301 (CF3Br), a broadly used fire suppressant, was out of production, except in developing countries and countries whose economies were in transition. The U.S. Department of Defense (DoD) had come to rely heavily on halon 1301 systems for many critical applications. One of these applications was for aircraft, which were vulnerable to fire during combat and needed in-flight fire protection during routine missions, a need shared by the commercial fleet. Initial research found that HFC-125 (C2HF5) was the best commercially available alternative fire suppressant for this use. However, this less efficient agent carried weight and storage volume penalties of up to a factor of three. Further research was needed on efficient and effective alternate technologies. In 1997, the DoD Next Generation Fire Suppression Technology Program (NGP) began, with an objective that evolved to "develop and demonstrate technology for economically feasible, environmentally acceptable and user-safe processes, techniques, and fluids that meet the operational requirements currently satisfied by halon 1301 systems in aircraft." In its decade of research, the NGP revitalized the field of fire suppression science. The NGP final report documents how the NGP came about, what research was performed, how it modernized the thinking in the field, and the technical findings for fire suppression in aircraft. Information regarding copies of the report can be found at www.bfrl.nist.gov/866/NGP. While the research focused on the extreme conditions operative in in-flight fires in aircraft engine nacelles and dry bays, much of the science and understanding (summarized below) is applicable to a broad range of fire scenarios.