Burning of a Polyurethane Slab in Open and in Room Environments

Abstract

To examine the effect of thermal feedback during a fire in a compartment, flexible polyurethane slab was burnt in an open environment and in a model-scale room. The size of the slab was 500 × 500 mm. The thickness was varied between 50 and 200 mm. The size of model-scale room was 900 × 1700 mm in plan area. Opening height was changed in the range of 200–800 mm to examine the effect of ventilation and smoke layer thickness. The ceiling height was varied in the range of 400–800 mm to examine the effect of extended flame under ceiling. The polyurethane slab was ignited at the center of top surface. Spread of flame was observed and recorded by video cameras. Mass loss rate, temperature profile, and heat fluxes to ceiling and floor were measured. Experimental results show that the thermal feedback effect is clearly observed even in the case of high ceiling with large openings. As the opening height was reduced, the effect of thermal feedback was increased moderately. At maximum, the heat release rate was increased to 170% of that in open burning. The effect of ceiling height was nonlinear. As the ceiling height was decreased comparable to continuous flame height, heat release rate was greatly increased due to the thermal feedback from extended flame under ceiling. Using the measured data, the effect of thermal feedback was correlated with heat flux to floor. Empirical relationships between ceiling height and fire growth rate, between maximum heat release rate and burning type index were derived.