Abstract: In order to further improve the technology level of forest fire prevention and reduce the loss and damage caused by forest fires, Yunnan pine, a common flammable species in southwest China, was selected as the burning material to build a fire extinguishing agent spraying wood stack fire test platform. The experimental study on the influence of three driving pressures （0.45、0.55、0.65 MPa） on the fire extinguishing efficiency of hydrogel extinguishing agent and Class A foam extinguishing agent was carried out, and comparative analysis was made based on the parameters of fire extinguishing time, consumption, cooling rate and effect of reducing heat radiation flux. The results show that when the driving pressure increases gradually, the fire extinguishing time decreases gradually, the flow rate increases, and the extinguishing agent consumption decreases gradually. When the driving pressure increases from 0.45 MPa to 0.55 MPa and 0.65 MPa respectively, the cooling rate of Class A foam agent increases by about 6% and 54%, and that of hydrogel agent increases by about 54% and 90%. With the increase of driving pressure, the decreasing heat radiation flux rate of extinguishing agent increases. Under the same driving pressure, the cooling depth of class A foam extinguishing agent is insufficient for burning wood battlements, and the fire of wood battlements cannot be effectively suppressed under the driving pressure of 0.45 MPa, while the hydrogel extinguishing agent can quickly extinguish open fire and effectively inhibit the reignition of smoldering wood.

Key words: fire agent, forest fires, Yunnan pine crib, driving pressure, fire extinguishing efficiency, thermal radiation flux