An experimental investigation on char pattern and depth at postflashover compartments using medium-density fibreboard (MDF)

To determine the fire origins for postflashover compartments, the char pattern and depth are investigated. A set of experiments was carried out using large-scale compartments made of medium-density fibreboard. A liquefied petroleum gas burner was used as the ignition source to mimic the fire origin. The burner was set at different locations in different experiments. It is found that time to flashover, intermittent flame of gas burner and ventilation condition have effects on the char patterns. The ventilation patterns' are likely to confuse the fire investigators; therefore, it needs to be identified from the flame patterns'. In general, the ventilation patterns at the floor would initiate directly from the compartment opening. CFD simulations is used to reflect the ventilation conditions during fires thus assisting the identification of ventilation patterns. For those cases with less distinguishable char patterns, the profiles of total leftover material thickness and char depth were used to determine the fire origin. The char layer and total thickness in the flame regions were found to be respectively deeper and thinner than the rest parts of the compartment. The ventilation condition also affects the char depth profile; therefore, it cannot be ignored from analysis. At the end, a strategy of fire origin determination is proposed. Copyright (c) 2014 John Wiley & Sons, Ltd.