Analysis of fire extinguishing performance and mechanisms in transformer oil pool fires by large-scale compressed nitrogen foam: Impact of different nozzle pressures

This article investigates the suppression of transformer oil pool fires using compressed nitrogen aqueous film-forming foam extinguishing agents with varying nozzle pressures (0.1–0.4 MPa), and a comprehensive analysis of fire extinguishing behavior and resistance to re-ignition was conducted. The research findings indicate that at a nozzle pressure of 0.4 MPa, there is a significant enhancement in fire extinguishing efficiency, with a reduction in extinguishing time by 15.0%–29.2%, and an increase in resistance to re-ignition by 32.2%–48.2%, making it the optimal choice. In comparison to the 0.1 MPa condition, the maximum instantaneous emissions of CO and SO2 at 0.4 MPa are only 66.7%. The interaction of various effects, such as atomization, results in a significant enhancement of flame intensification and fire extinguishing effects when compressed nitrogen aqueous film-forming foam is sprayed at high nozzle pressures. The study provides valuable insights for firefighters in the practical use of foam extinguishing agents.