Sustained effect of dry water in a thermal environment after fire extinguishing: Fuel surface coating methods

The elimination of heat and smoke hazards during the polymer combustion process is still challenging. In this work, we created a thermal environment using a fire propagation apparatus (FPA) and studied the sustained effect of dry water coated on the surface of polymer materials after fire extinguishing. The tests indicated an effective burnback delay and the reduction of heat and smoke hazards. This approach significantly increased the ignition time and reduced the heat release rate and the smoke and carbon monoxide production rate compared to fuel without dry water coating. The radiation intensity influenced the sustained performance of dry water, i.e., the larger the radiation intensity, the worse sustained performance. The sustained performance was also improved by using an aqueous solution as inner material. A low mass fraction of the aqueous solution yielded an improved sustained performance in the initial combustion stage. Furthermore, the gelation of dry water with the inner aqueous solution could balance the structural strength and the thermal shielding performance. These results have implications for designing a technical program toward longer escape and rescue times for stranded persons and firefighters.