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Ignition Delay of Combustible Materials in Normoxic Equivalent EnvironmentsMaterial 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 and32% oxygen concentration) is reduced by 27% compared to the standard atmosphere used in the Space Shuttle and Space Station. In order to determine whether there is a safer environment in terms of material flammability, a series of piloted ignition delay tests using polymethylmethacrylate (PMMA) was conducted in the FIST apparatus to extend the work over a range of possible exploration atmospheres. The exploration atmospheres considered were the normoxic equivalents, i.e. reduced pressure conditions with a constant partial pressure of oxygen. The ignition delay time was seen to decrease as the pressure was reduced along the normoxic curve. The minimum ignition delay observed in the normoxic equivalent environments was nearly 30% lower than in standard atmospheric conditions. The ignition delay in the proposed exploration atmosphere is only slightly larger than this minimum. Interms of material flammability, normoxic environments with a higher pressure relative to the proposed pressure would be desired.
Document ID
20110011524
Document Type
Other
Authors
McAllister, Sara (California Univ. Berkeley, CA, United States)
Fernandez-Pello, Carlos (California Univ. Berkeley, CA, United States)
Ruff, Gary (NASA Glenn Research Center Cleveland, OH, United States)
Urban, David (NASA Glenn Research Center Cleveland, OH, United States)
Date Acquired
August 25, 2013
Publication Date
January 1, 2009
Publication Information
ISSN: 0148-7101
Subject Category
Mechanical Engineering
Report/Patent Number
PB2010-102722
Paper 2009-01-2491
Meeting Information
SAE 39th International Conference on Environmental Systems(Savannah, GA)
Funding Number(s)
CONTRACT_GRANT: NNC-05GA02G
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.