SENSITIVITY OF MONOMETHYLHYDRAZINE (MMH) IN PYROVALVES

The sensitivity of MMH exposed to hot blow-by products of an actuated pyrovalve was experimentally evaluated using both a pyrovalve simulator and commercial pyrovalves in test configurations simulating a MMH-based propulsion system. The propulsion system may be used as an Interim Control Module (ICM) on the International Space Station and the influence of pyrovalve blow-by was a concern during system development. By comparison with results of previous pyrovalve simulator tests using water to establish water-hammer effects and tests using reactive hydrazine, MMH was found to be insensitive to blow-by in all tests performed. Specifically, results reported in this paper show no evidence that the blow-by caused a self-sustaining, exothermic decomposition event with MMH in three pyrovalve simulator tests, an ICM MMH tank outlet configuration test, or two ICM MMH tank inlet configuration tests.