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Total hydrocarbon analysis by ion mobility spectrometryAstronauts must be alerted quickly to chemical leaks that compromise their health and the success of their missions. An ideal leak detector would be equally sensitive to all compounds that might constitute a hazard and insensitive to nontoxic compounds. No ideal sensor exists; thus, selection of a methodology is a series of compromises. The commonly used methods are either insensitive at the low exposure levels set by OSHA, NASA, and other organizations or are selectively insensitive to important classes of chemicals such as Freons. After extensive study and experience, the Toxicology Group at JSC has selected ion mobility spectrometry (IMS) for development into a broad range, sensitive detector. In addition to the sensing method, signal processing is important leak detection because a background signal can be expected at all times. The leak-detecting instrument must be programmed to discriminate between authentic leaks and background fluctuations caused by routine operations. The results of an evaluation of the prototype THA is presented in terms related to spacecraft operations. The evaluation included determination of instrumental parameters such as stability and response times. We also included responses to some common components of spacecraft atmospheres in pure form and in binary and ternary mixtures. The output of the four algorithms to the mixtures was found to be noticeably different. These responses are compared on the basis of their utility for signaling a chemical leak. As a means of evaluating its resistance to a falsely positive response, the THA was challenged with carbon dioxide and methane, compounds whose concentrations normally increase in spacecraft air during human habitation. The instrument showed virtually no response to these interferences. Although the prototype THA is designed for space flight, this detector is expected to be useful for field screening at chemical waste dumps and other environmentally sensitive locations.
Document ID
Document Type
Conference Paper
Cross, John H.
(Krug Life Sciences, Inc. Houston, TX., United States)
Limero, Thomas F.
(Krug Life Sciences, Inc. Houston, TX., United States)
James, John T.
(NASA Lyndon B. Johnson Space Center Houston, TX, United States)
Date Acquired
September 6, 2013
Publication Date
January 1, 1994
Publication Information
Publication: Seventh Annual Workshop on Space Operations Applications and Research (SOAR 1993), Volume 2
Subject Category
Man/System Technology And Life Support
Accession Number
Distribution Limits
Work of the US Gov. Public Use Permitted.
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