A Study of the Extinguishment of Vertical Wood Slabs in Self-sustained Burning by Water Spray Application

Abstract

Experiments were carried out on the extinguishment of burning slabs of three different thicknesses. The results are presented in terms of experimental correlations of the mass lost during control and time required for control of the fire as functions of the rate of water application. A simple power law with exponent in the range (− 1·5) –(− 1·75) was found for the dependence of the first two variables on the latter.

The predictions of a theoretical scheme, based on a pyrolysis model for the solid, a simple estimate of the flame energy feedback and an extinguishment criterion for the flame, were found in good agreement with the experiment, The calculations confirmed the existence, already indicated by the experiment, of a minimum rate of water application ([mdot]_w ^# =0·19 –0·24 mg/ cm²/s) below which no mass is saved.

Furthermore, the theory indicated an upper limit, at [mdot]_w ^# = 0·8 – 1·0 mg/cm²/s, above which the efficiency of the water spray decreases.

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FRANCESCO TAMANINI

The author's rpesent address is Factory Mutual Research Corp., Norwood, Mass 02062.