Neutral-Gas Laser, Multipass-Cell Instrument for Monitoring Hydrazines

NASA space flight equipment test facilities require a monitoring device for airborne vapors of the rocket fuels hydrazine, monomethylhydrazine (MMH) and unsymmetrical dimethylhydrazine (UDMH). The ideal monitor will be portable, respond rapidly and specifically to hydrazines, and be sensitive at the 10 ppb level or below. Infrared direct absorption techniques have much to offer in terms of simplicity and specificity, but have been limited in their sensitivity. The proposed innovation is the use of the 910 . 63 cm- 1 Ne laser line as a reliable, stable and repeatable light source for the sensitive detection of hydrazines. When used in a system incorporating a novel longpath, low volume absorption cell currently produced by ARI, the detection sensitivity with a 1 second time response is projected to be below 10 ppbv for hydrazine. If Phase I results show that one of several detection options is applicable to MMH and UDMH, their detection limits will also be less than 10 ppbv.