Advanced Fire Suppression Technology for Aircraft: Findings of the Next Generation Fire Suppression Technology Program.
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.
Building and Fire Research Laboratory
National Institute of Standards and Technology
Gaithersburg, MD 20899