Experimental Investigation of Fire‐Extinguishing Performance and the Cooling Effect Based on Environmental‐Friendly Aqueous Film‐Forming Foam With Different Additives

Fluorocarbon surfactants are the most widely used stabilizers for enhancing the fire‐extinguishing (FE) efficiency of aqueous film‐forming foam (AFFF). However, perfluorooctane sulfonate (PFOS) generated by long‐chain fluorocarbon surfactants can exist in the food chain for a long time. It can pose a serious threat to the stability of the natural ecosystem. Therefore, the environmentally friendly substitutes for long‐chain fluorocarbon surfactants should be developed as soon as possible. This study explores the effects of expansion ratios, additive types, and additive mass concentrations on the FE time and cooling efficiency of AFFF for flammable liquid fires, showing that the FE process of AFFF consists of three stages: coupling, transition, and stable periods. The minimal FE time, at which the surface temperature of combustibles was significantly reduced, was obtained when the gas–liquid mixing ratio and additive mass concentration were 4:1 and 0.3 wt.%, respectively. The synergistic effects of MCA and FS‐50 quickly reduced fire source temperatures, further enhancing the FE effectiveness of modified AFFF. A series of tests have proven that the AFFF foam mixed with environmentally friendly additives achieved the fire extinguishing requirements specified in national standards.