Fire Safety Science Digital Archive

An extensive research program on combustible wall lining materials has been carried out in Sweden. A computer model, which as closely as possible describes the physical processes of flame spread and fire growth, is presented using material properties derived from standardized bench--scale tests as input data. These parameters are thermal inertia k?c, flame spread parameter ?, ignition temperature Tig and RHR-parameters Qmax and ?. (Time variation of RHR is assumed to be written Q”(t) = Q”max e-?t). The computer based model simulates the fire growth in the full or 1/3 scale tests, which includes predicting the rate of heat release, gas temperatures, radiation to walls, wall surface temperatures and downward flame spread on the wall lining material. Prediction has been validated against experimental room tests. When using the computer model for practical purposes an analytical expression summarizing the results of the calculation is highly advantageous. Applying regression analysis to the computer model results, the following expression was derived for time to flashover tfo = 3.08 * 105 (k?c)0.75 ?-0.37 ?0.11 (Q”max)-0.52 with the coefficient of determination R2 = 0.98. The importance of the expression above is that a material classification criterion has been explicitly expressed as a function of bench scale test results [12]. This opens totally new approaches to a rational material classification. Some of these new avenues are briefly introduced in the paper.