A simplified theory for generalizing results from a radiant panel rate of flame spread apparatus

Experimental results on the rate of lateral flame spread and time for piloted ignition under an externally imposed radiant flux were analyzed with a simple theroretical model. The data were developed from a radiant panel apparatus that considers a wall mounted sample with a flux distribution {article}{empty}{document}( qₑ ){document} of 5 W cm −2 at the ignited end to 0.2 W cm −2 at the other end. It is shown that after an appropriate preheating time (flux exposure time before sample is ignited) the rate of flame spread ( V f ) results can be correlated by {article}{empty}{document}Vf - 1 2 = C( q''_ o,ig - qₑ ){document} where C is a material ‘constant’ and {article}{empty}{document}q'' _ o,ig{document} is minimum flux for piloted ignition—also a material (and configuration) constant. An extension of this model demonstrates that V f can also be expressed in terms of an ‘ignition temperature’ and the surface temperature of the material. Both correlations are derivable from a single flame spread experiment. Results are presented for a number of typical wood and plastic materials.