Comparative Study of the Suppression Behavior and Fire-Extinguishing Mechanism of Compressed-Gas Aqueous Film-Forming Foam in Diesel Pool Fires

A compressed-gas fire extinguishing experiment was carried out to analyze the impact of gas-liquid flow ratio, liquid flow rate and driving pressure on the fire suppression efficiency of aqueous film-forming foam (AFFF) in a diesel pool fire, and a possible fire-extinguishing mechanism was proposed. A fire suppression test showed that AFFF at a gas-liquid flow ratio of 16 between the range of 5 to 24 had the fastest fire-extinguishing temperature drop rate (16.67 °C/s), the shortest fire-extinguishing time, of 42 s, and the lowest foam solution consumption of 230 g, exhibiting the best fire suppression performance. Meanwhile, the fire suppression efficiency of AFFF improved with the augmentation of either liquid flow rate or system driving pressure. Based on fluid mechanics and combustion science, a foam fire-extinguishing mechanism was proposed to explain the influence of system parameters such as gas-liquid ratio, liquid flow rate and driving pressure on key combustion parameters such as temperature drop rate, evaporation rate and combustion rate, which can better illustrate the change in fire extinguishing performance.