Extinction of Nonpremixed Flames With Halogenated Fire Suppressants.
Extinction of Nonpremixed Flames With Halogenated Fire
Hamins, A.; Trees, D.; Seshadri, K.; Chelliah, H. K.
Combustion Institute. Symposium (International) on
Combustion, 25th. Proceedings. Abstracts of Symposium
Papers. Session 06-K: Fire Suppression. July
31-August 5, 1994, Irvine, CA, Combustion Institute,
Pittsburgh, PA, 62 pp, 1994 AND Combustion Institute,
Symposium (International) on Combustion, 25th.
Proceedings. July 31-August 5, 1994, Irvine, CA,
Combustion Institute, Pittsburgh, PA, 1994, 1994.
Combustion and Flame, Vol. 99, No. 2, 221-230, 1994.
extinction; fire extinguishing agents; flame
extinguishment; flame retardants; flame structure; halon
1301; halogenated compounds; radicals
An experimental, analytical, and numerical study was
performed to elucidate the influence of eleven gaseous
agents, considered to be substitutes for CF3Br, on the
structure and critical conditions of extinction of
diffusion flames burning liquid hydrocarbon fuels. The
effectiveness of these agents in quenching flames was
compared to those of CF3Br and an inert diluent such as
nitrogen. Experiments were performed on diffusion flames
stabilized in the counterflowing as well as in the
coflowing configuration. The fuels tested were heptane
in the counterflowing configuration, and heptane, the
jet fuels JP-8, and JP-5, and hydraulic fluids (military
specifications 5606 and 83282) in the coflowing
configuration. The oxidizing gas was a mixture of air
and the agent. On a mass and mole basis CF3Br was found
to be most effective in quenching the flames and the
mass-based effectiveness of the other eleven agents was
found to be nearly the same as that of nitrogen.
Experimental results were interpreted using one-step,
activation-energy asymptotic theories and the results
were used to provide a rough indication of the thermal
and chemical influence of these agents on the flame
structure. To understand in some detail the influence
of CF3Br on the structure and mechanisms of extinction
of the flame, numerical calculations using detailed
chemistry were performed. The calculated structure of
counterflow heptane-air diffusion flames inhibited with
CF3Br was found to consist of three distinct zones
including a CF3Br consumption zone which appears to act
as a sink for radicals. The calculated values of the
critical conditions of extinction of counterflow
heptane-air diffusion flames inhibited with CF3Br were
found to agree fairly well with measurements. The study
suggests the need for refinement of the inhibition