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Parametric Study of Hydrogen Fluoride Formation in Suppressed Fires.


pdf icon Parametric Study of Hydrogen Fluoride Formation in Suppressed Fires. (1005 K)
Linteris, G. T.; Gmurczyk, G. W.

Halon Options Technical Working Conference. Proceedings. HOTWC 1995. May 9-11, 1995, Albuquerque, NM, 227-238 pp, 1995.

Keywords:

hydrogen fluorides; chemical inhibition; flame chemistry; flame models; flame retardants; experiments; halon alternatives

Abstract:

Some of the proposed replacements for CF3Br, the fluorinated hydrocarbons, are required in higher concentrations to extinguish fires and contain more halogen atoms per molecule. Since they decompose in the flame, they produce correspondingly more hydrogen fluoride than CF3Br when suppressing a fire. Recent laboratory experiments with burners using heptane, propane, and methane have indicated that the amount of HF formed in steady state can be estimated within about a factor of two for diffusion flames and within 10% for premixed flames based on equilibrium thermodynamics. In this model for HF formation, the inhibitor molecule is transported to the reaction zone by convection and diffusion and is consumed in the flame sheet to form the most stable products (usually HF, CO2, and COF2). In the present work, the equilibrium model is used to estimate the upper limit of HF formation in suppressed fires. The effects of fuel and agent type, fuel consumption rate, and agent injection rate are included in the model, as are room volume, humidity, and concentration of inhibitor necessary to extinguish the fire. Results are presented for a range of these parameters, and the predictions are compared, when possible, with the results of laboratory and intermediate-scale experiments.