Fire Safety Science Digital Archive

A simplified thermal model of piloted ignition is formulated. The model equations are then solved numerically for the thermally thick case using a finite difference technique. A systematic analysis of some solutions leads to a functional relationship between ignition time tig, and irradiance q”e, suitable for correlation of piloted ignition data. This suggests plotting ignition data in a graph of (tig)-0.547versus q”e. The critical irradiance q”cr is then found as the intercept with the abscissa of a straight-line fit through the data. An apparent krc can be obtained from the slope of the regression line. Theoretical calculations show that this apparent krc for wood products is evaluated at a temperature approximately halfway between T? and Tig. The suggested correlating procedure is applied to measurements for six oven dry wood species obtained in the Cone Calorimeter.