Experimental Investigation of Extinguishment of Laminar Diffusion Flames by Thermal Agents.
Experimental Investigation of Extinguishment of Laminar
Diffusion Flames by Thermal Agents.
Yang, J. C.; Bryant, R. A.; Huber, M. L.; Pitts, W. M.
Halon Options Technical Working Conference.
Proceedings. HOTWC 2000. Sponsored by: University of
New Mexico, Fire Suppression Systems Assoc., Fire and
Safety Group, Great Lakes Chemical Corp., Halon
Alternative Research Corp., Hughes Associates, Inc.,
Kidde Fenwal, Inc., Kidde International, Modular
Protection, Inc., Next Generation Fire Suppression
Technology Program, Sandia National Laboratories, Summit
Environmental Corp., Inc. and 3M Specialty Materials.
May 2-4, 2000, Albuquerque, NM, 433-446 pp, 2000.
Available from:For more information contact: Center for Global
Environmental Technologies, New Mexico Engineering
Research Institute, University of New Mexico, 901
University Blvd., SE, Albuquerque, NM 87106-4339 USA.
Fax: 505-272-7203. WEB:
halon alternatives; laminar flames; diffusion flames;
extinguishment; liquids; burners; reaction kinetics;
flame extinguishment; halons
As part of the National effort to identify effective
replacements for halon fire suppressants, NIST has been
investigating whether highly effective thermal agents
are feasible. Thermal agents are defined as those that
obtain their effectiveness solely by heat extraction and
dilution. Excluded from investigation are species that
directly or indirectly disrupt the combustion chemistry
such as halons, which derive much of their effectiveness
by the release of bromine atoms that catalytically
remove hydrogen atoms in the flame zone. A NIST Internal
Report is available describing the findings of the first
year of this investigation. A thorough search of NIST
thermodynamic databases was performed to identify
molecular species that might be particularly effective
thermal agents. Detailed chemical kinetic modeling of
laminar opposed jet diffusion flames was used to predict
extinguishing concentrations and provide insights into
extinguishment mechanisms. Methane flames burning in air
diluted with the known thermal agents nitrogen (N2),
argon (Ar), helium (He), carbon dioxide (CO2), and water
(H2O), as well as artificial surrogate agents, were
considered. These findings were summarized during the
1999 HOTWC meeting. The third part of the study was an
analysis of the interaction of liquid droplets with
surfaces in order to characterize the physical
properties desirable for liquid agents. The database
search identified two chemicals that were predicted to
be particularly effective at extracting heat from a
flame zone. The first was methoxy-nonaflurobutanc
(C4F9OCH3), also known as HFE7100, which was one of the
highest rated thermal agents on both mass and molar
bases. The boiling and freezing points are 334 and 138
K, respectively. Extinguishing molar concentrations in
air for the gas were reported as 6.1% in a cup-burner
test using heptane fuel and in a "micro cup-burner" test
burning butane. No measurements of the effectiveness of
this compound when released as a liquid were available.