Influence of gas-liquid ratio on the fire-extinguishing efficiency of compressed gas protein foam in diesel pool fire

The fire-extinguishing efficiency of compressed gas protein foam with different gas-liquid ratio on diesel pool fire was studied by a laboratory-scale fire suppression experiment. The 25% drainage time, expansion ratio and fire-extinguishing efficiency of 6% protein foams (PF) with the gas-liquid ratio in the range of 5-24 were tested. The results show that as gas-liquid ratio increases, both the 25% drainage time and expansion ratio increase. In the fire-extinguishing process, the temperature drop rate increases at the beginning and then decreases with the increase of gas-liquid ratio. When the gas-liquid ratio is 20, the foam shows the optimal equilibrium between the fluidity and stability, thus exerting the maximum temperature drop rate of 6.86 K s(-1)corresponding to the best fire-extinguishing efficiency. The main fire-extinguishing mechanism of PF in pool fire is ascribed to the combined actions of cooling effect and barrier effect. By adjusting the gas-liquid ratio in the range of 16-24, the PF can exert excellent fire-extinguishing efficiency in pool fire by diluting the combustible gases and isolating the transmission of heat and oxygen between combustion zone and fuel.