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Abstract

Small-scale experiments are performed to determine the influ ence of noncombustible coating material on the behavior of flame propagation over solid fuels. Thick polymethylmethacrylate (PMMA) sheets are used as com bustible materials, and sand layer is used as the solid coating material in the ex periments. The results of the experiments show that the size of the sand and the thickness of the sand layer have significant effects on the flame spread rate. The influence is through the amount of heat flux absorbed by the unburned fuel sur face and the mass diffusion of the vaporized fuel to react with the oxygen in the ambient air. As the sand layer thickness increases, the flame spread rate de creases. An inverse trend is observed with the increase of the sand size. In this pa per, a simplified heat transfer model is proposed for the flame spread rate over the combustible material with a layer of noncombustible porous material. The exper imental results have been found to be in agreement with the results from the model. Results from this study can be used in two areas. One is in understanding how flame spread is retarded by application of porous material as an extinguish ing agent. Another aspect is that more and more household items nowadays have a noncombustible coating on the surface as a means of decoration, more funda mental information on how the flame spreads is useful in future building fire safety designs.

Keywords

flame spread heat flux flame length mass burning rate

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Flame Spread Over Solid Surface Coated with a Layer of Noncombustible Porous Material

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