Application of investigation techniques to identify an arson fire

Determining the cause of an arson fire is the most difficult part of fire investigation. In this study, the researcher used various clues and several pieces of fire debris collected from the actual fire site to conduct a series of experiments and analyses in sequence, starting from metallographic analysis to inductively coupled plasma optical emission spectrometry and then a thermal analysis experiment to determine the cause of a fire. It was found that when the temperature was elevated at a rate of 2 °C/min, polyurethane (PU) foam, a structural component of refrigerators, started thermal decomposition. At about 130 °C, the thermal decomposition accelerated, and eventually at 384 °C, about 4883.33 J/g of maximum heat was released. In the end, remaining debris was about 4.96%. Therefore, the combustion of PU foam is an ultrafast type of combustion reaction. The content as well as the experimental procedure of the study is useful for fire investigators in determining the cause of arson fires.