Experimental Study on upward Flame Spread of Exterior Wall Thermal Insulation Materials

The objective of this paper was to gain an understanding of the upward flame spread phenomenon of thermal insulation materials as extruded polystyrene (XPS) and polyurethane (PU) foams. Plenty of these materials sustained flame spread under line n-heptane fire source regardless of edge effects. Different flame spread phenomena of XPS and PU were observed and the heat release rate was captured to analyze their burning performance. Flame height was recorded as a function of heat release. Relationship between flame height and total heat flux was revised to quantitatively investigate the effect of the line fire source on flame-retarded and non-retarded materials. This result was predicted in terms of measured fuel thermophysical properties, flame heights and heat feedback to the fuel surface. Total heat feedback to the sample was measured. The upward spread rate for vertical PU slabs during the early-stage burning was observed to increase exponentially with time.