Optimization of System Discharge.
Optimization of System Discharge.
(16676 K)
Yang, J. C.; Cleary, T. G.; Vazquez, I.; Boyer, C. I.;
King, M. D.; Breuel, B. D.; Womeldorf, C. A.;
Grosshandler, W. L.; Huber, M. L.; Weber, L.; Gmurczyk,
G. W.
NIST SP 890; Volume 1; Section 8; November 1995.
Fire Suppression System Performance of Alternative
Agents in Aircraft Engine and Dry Bay Laboratory
Simulations. Volume 1. Section 8, Gann, R. G.,
Editor(s), 407-782 pp, 1995.
Available from:
National Technical Information Service
(NTIS), Technology Administration, U.S. Department of
Commerce, Springfield, VA 22161.
Telephone:
1-800-553-6847 or 703-605-6000;
Fax: 703-605-6900.
Website: http://www.ntis.gov
Order number: PB96-117775
Keywords:
fire suppression; aircraft engines; nacelle fires;
simulation; thermophysical properties; nitrogen;
discharge rate; computer simulation; halon 1301; halon
alternatives
Abstract:
Current aircraft fire suppression bottles for dry bay
and engine nacelle applications, which are designed to
meet Military Specification MIL-C-22284A (proof pressure
of 9.62 MPa and minimum burst pressure of 12.37 MPa),
are normally filled with liquid halon 1301 (CF3Br) to
about half of the bottle volume, and the bottle is then
pressurized with nitrogen to a specified equilibrium
pressure (typically 4.1 MPa) at room temperature. The
purpose of using the pressurization gas is to expedite
the discharge of the agent and to facilitate the
dispersion of the agent. Without nitrogen
pressurization, the bottle pressure, which is simply the
vapor pressure of the agent, can be so low (even
sub-atmospheric) at extremely cold ambience that there
is virtually no driving force to expel the agent from
the bottle in case of a fire, thus hindering a rapid
release of the mixture. From the above description,
three important issues have emerged and need be
considered when using a halon alternative as an
in-flight fire suppressant: (1) the system hardware,
(2) the thermophysical properties of the agent/nitrogen
mixture, and (3) the agent/nitrogen mixture behavior
during a discharge. The results obtained from this
study provide important technical information on bottle
design and agent discharge for new generation aircraft
that may use the halon alternatives, for the existing
aircraft that may undergo retrofitting, or simply for
possible "drop-in" replacements.
Building and Fire Research Laboratory
National Institute of Standards and Technology
Gaithersburg, MD 20899