Study on hazard characteristics and safety distance of small-scale boilover fire

Boilover is one of the most destructive tank fire scenarios, occurring in the specific conditions of explosive evaporation of the water sublayer, which causes a sudden rise in flame height accompanied by the splashing of burning fuel. In order to estimate the thermal hazards of the boilover fire, a series of experiments were conducted where the influence of pool diameters, initial fuel layer thickness and fuel types on the boilover characteristics were investigated. The results show that the boilover fire can be divided into four stages including the initial stage, steady stage, boilover stage and decay stage. The boilover onset time which is defined based on the flame enlargement, show a slight downward trend with the pool diameter but increased with the initial fuel layer thickness. The boilover intensity defined based on the mass loss rate increased with the fuel layer thickness but decreased with the pool diameter. Analysis of these phenomena was conducted based on the thermal mechanism of the boilover occurrence. The boilover splash coverage ratio is approximately exponentially distributed with distance. A model for predicting the safe distance based on boilover splash is derived by introducing the boilover intensity and critical thickness at which boilover occurs. The present results provide a guidance for boilover fire prevention during fuel storage and transportation.

Automated summary

Boilover fire is a dangerous scenario that can be divided into four stages and is influenced by various factors. By analyzing this phenomenon based on thermal mechanism, a safe distance can be predicted.