Study on fire risk of typical thermal insulation materials based on pyrolysis, combustion and flame spread experiments

Thermal insulation materials are widely installed in buildings, but they are greatly flammable and have caused many fires. Therefore, it is essential to estimate their fire risk. There are several significant stages in the combustion process of solid combustibles. They will produce gas at the pyrolysis stage. If the concentration of pyrolysis gas is high enough, pyrolysis gas can be burned after mixing with air. Finally, the burning flames spread, causing a large-scale fire. Thus, the combustion characteristics of solid combustibles can be understood through the parameters from multiple stages. The characteristics of expanded polystyrene (EPS) were comprehensively studied using thermogravimetry, cone calorimeter and flame spread experiments, and its fire risk was characterized using the analytic hierarchy process method. The results showed that EPS had stable activation energy during the pyrolysis, ranging from 203 to 235 kJ/mol. Ignition time was short (7–19 s), and peak heat release rate was 102–166 kW/m² and smoke production rate (SPR) was 0.06–0.13 m²/s. Furthermore, flame spread performance displayed that because of the different flame spread rates of wall fire and pool fire, there were regular fluctuations in flame temperature. The flame height of the pool fire was greater than that of the wall fire. Flame spread rate, flame temperature and SPR had the greatest impact on the fire risk. This study helps to understand fire risk from multiple stages and determine the weight of different factors, so as to take appropriate measures to reduce the fire risk.