Mass Flow Measurement of Gaseous Breathing Air Through the Liquid Air Pack Respirator
The Kennedy Space Center Liquid Air Pack respirator currently uses an electronic timer to control the service life of the respirator during operation. The pre-set timer cannot sense the remaining air supply in the respirator and is not programmed to account for changes in human respiration rates. A timer is an acceptable end of service life indicator for this type of respirator. Flow meters were evaluated as alternatives to the timer. The objective of the evaluations was to determine if a mass flow meter could accurately measure the breathing air consumed during use of the respirator. Two laboratory tests of a Teledyne-Hastings mass flow meter were performed in the NASA Kennedy Space Center Biomedical Laboratory. The meter was connected in series with the Liquid Air Pack respirator for a human subject test and for a breathing machine test. The meter measurement readings were documented on a strip chart recorder for the two tests. The meter was tested without a chamber to dampen flow fluctuations created in breathing. This is the first application of a mass meter with KSC or commercial respirators. The mass flow measurement data could be integrated and used to display the status of air remaining in the respirator during operation. A complete package consisting of a meter, integrator, warning horn and appropriate electronics could replace the existing timer. The total mass flowing from the Liquid Air Pack is derived from the strip chart records and converted into total weight. These data are compared to the weight of the respirator before and after the flow testing. In each case, the meter measurements are within five percent accuracy when compared to the reference scale weight changes. This close agreement of the data infers the characteristics of the meter are adequate for use as a service life indicator. Projection of the meter accuracy at the higher breathing rates was explored. Testing of a smaller mass flow meter is recommended prior to field application with the Liquid Air Pack.
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Master of Science (M.S.)
College of Engineering
Mechanical and Aerospace Engineering
Length of Campus-only Access
Masters Thesis (Open Access)
Dissertations, Academic -- Engineering; Engineering -- Dissertations, Academic
Carlson, Carol Weber, "Mass Flow Measurement of Gaseous Breathing Air Through the Liquid Air Pack Respirator" (1991). Retrospective Theses and Dissertations. 3804.