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Material flammability is an important factor in determining the pressure and composition (fraction of oxygen and nitrogen) of the atmosphere in the habitable volume of exploration vehicles and habitats. The method chosen in this work to quantify material flammability is by its ease of ignition and the minimum (critical) radiant heat flux for ignition. Piloted ignition delay tests were conducted in the Forced Ignition and Spread Test (FIST) apparatus subject to various atmospheric pressures and oxygen concentrations. The ignition delay time was measured as the time it takes a combustible material to ignite after it has been exposed to an external heat flux. In these tests, polymethylmethacylate (PMMA) was exposed to an oxidizer flow velocity of 1 m/s and a range of externally applied heat flux levels from 8 to 14 kW/m2.

Material flammability is an important factor in determining the pressure and composition (fraction of oxygen and nitrogen) of the atmosphere in the habitable volume of exploration vehicles and habitats. The method chosen in this work to quantify the flammability of a material is by its ease of ignition. The ignition delay time was defined as the time it takes a combustible material to ignite after it has been exposed to an external heat flux. Previous work in the Forced Ignition and Spread Test (FIST) apparatus has shown that the ignition delay in the currently proposed space exploration atmosphere (approximately 58.6 kPa and 32% oxygen concentration) is reduced by 27% compared to the standard atmosphere used in the Space Shuttle and Space Station.