Combustion Mechanism of Polyurethane Foam in Refrigerated and Frozen Warehouses Based on Fire-Case Analysis

The PAMS refrigerated and frozen logistics warehouse in Pyeongtaek-si, Gyeonggi-do experienced a fire in January 2022. This event exhibited distinct characteristics compared to existing fire cases because of architectural variations. Notably, the main structural component was fire-resistant, and the floor height was elevated. Consequently, conducting research on fire prevention and response strategies specific to the built environment of refrigerated and frozen warehouses with increased floor heights is imperative. A 1/10th scale model of the actual PAMS warehouse (room 208) was constructed for reproduction experiments. Additionally, basic experiments were conducted using the samples of polyurethane foam collected from fire sites. During these basic experiments, the polyurethane foam was ignited at approximately 315 ℃. Furthermore, thermogravimetric analysis revealed a complete decomposition of the foam at approximately 388 ℃, accompanied by a significant mass reduction rate of approximately 80%. Intriguingly, our observations of the 1/10th scale model, even with the loading dock entrance remaining open, indicated the presence of pulsating smoke, suggesting a backdraft event. Upon opening the upper part of the neutral zone, rapid combustion occurred. These findings indicate that the introduction of oxygen through a collapsed upper wall section in refrigerated and frozen logistics warehouses, even during the decline phase of a fire, can induce rapid changes in the combustion behavior of polyurethane foam. These findings should be considered for the development of fire prevention and response protocols for such facilities.