Abstract: Aqueous film-forming foam (AFFF) fire agents can effectively extinguish transformer oil fires, however, traditional AFFF contains PFOS, which is toxic and carcinogenic. Therefore, there is an urgent need to develop environmentally friendly foam agents that eliminate the use of PFOS. This study explores various combinations of active surfactants and analyzes their surface/interfacial properties. The findings reveal that there is a synergistic effect between hydrocarbon anionic surfactants and hydrocarbon nonionic surfactants, and a complementary effect between hydrocarbon anionic surfactants and either silicone nonionic surfactants or short-chain fluorinated surfactants. Additionally, a complementary effect was also observed between hydrocarbon anionic surfactants and fluorocarbon surfactants. Spreadability and fire tests demonstrate that the fluorine-free surfactant system proposed in this study performs comparably to the latest fluorinated eco-friendly foam agents in both spreadability and extinguishing efficiency and significantly outperforms commercial AFFF products.

Key words: fluorine-free foam extinguishing agent, transformer oil, spreadability test, synergistic effect