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Material Flammability Test Assessment for Space Station Freedom.


pdf icon Material Flammability Test Assessment for Space Station Freedom. (2501 K)
Ohlemiller, T. J.; Villa, K. M.

NISTIR 4591; NASA CR-187115; 78 p. June 1991.

Sponsor:

National Aeronautics and Space Administration, Lewis Research Center, Cleveland, OH

Available from:

National Technical Information Service
Order number: PB91-216606

Keywords:

flame spread; flammability; ignition; microgravity; heat release rate; test methods; spacecraft; small scale fire tests; lexan (trademark)

Abstract:

The NASA Upward Flame Propagation test, which measures response to a well-defined laminar flame at the bottom of a test sample, is currently used to screen for flammability all materials intended for use in the interior of manned spacecraft. The response of a series of materials was compared in this test and in the standard NIST Flammability Tests (Cone Calorimeter for rate of heat release and LIFT tests for ignitability and lateral flame spread). The goal was to see if these differing flammability assessment approaches provide comparable information on the potential hazards of a material. In the first phase of this study only one of the samples exhibited appreciable flame spread in the NASA test, yielding very limited data for comparisons with the NIST test results. The NIST tests, which employ a variable external radiant flux as an additional test parameter, revealed a widely varying response to this flux. In the second phase of the study, the NASA test was modified to include radiative pre-heating of the samples before they were exposed to the standard NASA ignitier in the standard manner. The response of the materials, as measured by the minimum pre-heat flux (or temperature) to yield upward spread, varied widely; for example, Nomex required very little pre-heating to yield full-length spread whereas Lexan 9034 was resistant. Rate of heat release behavior or lateral flame spread behavior alone did not appear to be predictive of behavior in the modified NASA test. A simplified upward flame spread model, which utilizes inputs derived from the NIST test, was employed in an attempt to predict the behavior in the modified NASA tests. The model greatly under-predicted the necessary pre-heat flux for some materials while doing the opposite for other materials. Thus, at the present, a firm relation between the behavior in the NASA test and in the NIST tests has not been established.