An assessment of the NASA flammability screening test and related aspects of material flammability

摘要

The results of an assessment of the NASA flammability screening test (8060.1B) for materials to be used in manned spacecraft interiors are summarized. A set of materials was examined using the standard NASA test, a modified version of this test which incorporated external radiation and National Institute of Standards and Technology (NIST) tests which measure ignitability, rate of heat release, and opposed flow flame spread behavior. Materials passing the standard NASA screening test showed widely varying degrees of flammability enhancement when subjected to external radiation (modified NASA test, NIST tests). Since such radiation is implicit in many normal fire scenarios, materials passing the standard NASA screening test should not be treated as non-flammable. The quantitative role of self-feedback of radiation remains to be fully clarified; an apparatus to examine this issue was built but no tests could be completed in the allotted time. The rate of heat release from the two-sided burning of thermally-thin materials was quantitatively compared to that for one-sided burning; this issue was believed to be at the heart of certain anomalies in the earlier stages of this study. A synergistic enhancement of heat release rate was indeed found for two-sided burning of three materials; two simplified models account for the origin of this effect. On the basis of this study, it is recommended that NASA supplement their existing flammability screening test with one that incorporates external radiation. It is further recommended that this supplemental test in normal gravity be correlated experimentally with a similar test in micro-gravity.