Study on the Effectiveness of NH ₄ H ₂ PO ₄ Powder in Inhibiting the Pyrolysis Gas Flame of Coniferous Woods and Its Suppression Mechanism

High Resolution Image Download MS PowerPoint Slide Forest fires are one of the key challenges and focus areas in the field of fire science research today. Due to the complex multiphase coupling and rapid spread characteristics of forest fuels, such fires are often difficult to extinguish directly. As a typical solid fuel, the flame spread of wood is essentially the result of the coupling between solid-phase pyrolysis and gas-phase combustion chemical reactions. Therefore, by inhibiting either solid-phase pyrolysis or gas-phase combustion, the spread of flames in wood can be effectively restrained, providing important support for subsequent fire suppression. Previous studies on forest fire suppression have largely focused on the macroscopic inhibitory effects of various extinguishing agents on overall fire behavior. Although fire suppression effectiveness parameters can be obtained through repeated experiments, they often lack in-depth analysis of the microscopic interactions between extinguishing agents and flames. To address this, this study begins with the key aspect of gas-phase combustion suppression, attempting to construct a scaled-down experimental model to focus on the chemical suppression effects of extinguishing agents in the gas phase. The study selects typical coniferous species and uses pyrolysis analysis to obtain their gas-phase combustion components. Based on this, a cup-type burner experimental system is developed to extinguish the pyrolyzed gas flame of coniferous wood with ammonium dihydrogen phosphate powder. Although this system simplifies the solid fuel and multiphase combustion interface found in real forest fires, it helps explore, under controlled conditions, the dynamic evolution of flame suppression by powders, revealing their chemical suppression characteristics and mechanisms. This, in turn, provides theoretical and experimental support for understanding and further improving the effectiveness of powder extinguishing agents in complex fire scenarios.