Flame spread over a fire resistant fabric under external heating

Fire resistant materials are clearly preferred for fire-risk applications but their flammability is usually tested under very specific conditions that might not represent the real fire situation. In this work, we investigate the effect of ambient pressure and oxygen concentration on the upward flame spread over Nomex HT90-40 exposed to two different external heat sources. One is the radiation from infrared lamps and the other is the flame from a burning polymethyl methacrylate (PMMA) sheet placed below the fabric. The limiting oxygen concentration (LOC) was first quantified under different external heating, and then the upward flame-spread rate above LOC was measured. Experiments show that the flame from nearby burning object not only can ignite the fire resistant fabric, but also extend the LOC of the material to lower oxygen concentrations. Moreover, the heating from the attached flame is different from an external radiant flux. The results of this work also provide important information about the fire interactions of different materials, and guide the future fire safety design in space exploration.