Quantitative review of experimental tests and theoretical models of flashover occurrence in compartment fires

Abstract

In performance-based fire design (PBFD), flashover is the rapid transition from a growing to a fully developed fire. In this study, a comprehensive literature review and analysis of 93 large-scale compartment fire experiments were conducted to identify the key factors that affect the HRR required for flashover (Q_FO). For each fire test, key parameters were documented, including fuel load, fuel type, compartment configuration, ventilation properties, boundary characteristics, and the heat release rate (HRR)-time curve. The impact of each parameter on Q_FO was assessed through comparison with experimental data. It was shown that there are direct correlations between these parameters and Q_FO. Moreover, available analytical models to predict Q_FO were compared against the compiled experimental results. Based on experimental data, an equation was proposed to estimate Q_FO by considering the effect of fuel load, opening factor, boundary characteristics, and compartment shape. These parameters, not previously used all together in other models, resulted in improved accuracy, with the proposed model achieving a mean squared error (MSE) of 0.46 and an R² value of 86 %, outperforming other theoretical models. The average time to flashover onset, calculated using the proposed equation based on 8800 different scenarios of the same compartment as a case study, varies from 1 min for an ultra-fast fire to 11 min for a slow-growing fire, indicating the need for a fire safety strategy that accounts for different parameters influencing flashover.