Pool fire suppression performance of foams stabilized by PEO-PPO-PEO triblock copolymers

The PEO-PPO-PEO triblock copolymers have the potential to develop the available fluorine-free foam replacing the aqueous film-forming foam for pool fire suppression. In this study, five PEO-PPO-PEO copolymers with different molecular weights and EO/PO ratios were studied for foam application to suppress the pool fire compared with the performance of APG foam, and the correlation of foam thermal stability and foam viscosity with the fire suppression performance was researched. In fire extinction tests, F127 foam and F108 foam with dense and stable layers covering the ignited heptane surface and APG foam with superior spreading performance showed the shortest extinction time. In burnback tests, F127 foam and F108 foam exhibited outstanding suppressing burnback performance than other foams and they could form the reversible localized gel foam triggered by the increasing temperature. The burnback time of the F108 foam was up to 22 min over 12 times longer than the APG foam. The suppressing burnback performance of the six studied foams was consistent with their foam stability on the heating heptane surfaces, and the foam spreading rate in the extinction tests correlated highly to the foam viscosity but was also affected by the foam thermal stability.