Experimental study of altitude and orientation effects on heat transfer over polystyrene insulation materialIgnition and combustion behaviors

In order to reveal the altitude and orientation effects on the flammability behaviors of insulation material of polystyrene, a series of comparative lab-scale experiments was carried out in plain area of Hefei and plateau area of Lhasa. The piloted ignition time was identified for EPS and XPS with sample orientations of 0°, 15°, 30° and 90°. It was found that the piloted ignition time was shorter in Hefei than that in Lhasa for the same slab at the same inclination. Meanwhile, for EPS, due to the greater shrinkage, the ignition time was not influenced by thickness obviously, while for XPS, it was decreased with thickness for the receiving heat flux enhanced. The ignition time during flame spread case was longer than that in piloted ignition, attributed to the longer time of shrinking and melting. The combustion characteristics including pool fire length, flame length and mass loss rate were also explored. With the sample thickness increase, the maximum pool fire length and mass loss rate were both increased, leading to greater fire hazard. For the dripping and smoke influence, the slope of flame length against pyrolysis length at 90° would increase from slope1 to slope2.