Pressure effects on oxygen concentration flammability thresholds of polymeric materials for aerospace applications

Spacecraft materials selection is based on an upward flammability test conducted in a quiescent environment at the highest expected oxygen concentration. However, NASNs advanced space exploration program is anticipating using various habitable environments. Because limited data are available to support current program requirements, a different test logic is suggested to address the expanded atmospheric environments through the determination of materials self-extinguishment limits. This paper provides additional pressure effects data on oxygen concentration and partial pressure self-extinguishment limits under quiescent conditions. For the range of total pressures tested, the oxygen concentration and oxygen partial pressure flammability thresholds show a near linear dependence on total pressure, and appear to increase with increasing oxygen concentration (and oxygen partial pressure) thresholds. For the Constellation Program, the flammability threshold information will allow NASA to identify materials with increased flammability risk from oxygen concentration and total pressure changes, minimize potential impacts, and allow for development of sound requirements for new spacecraft and extraterrestrial landers and habitats.