Development of an advanced rocket propellant handler's suit.
Most launch vehicles and satellites in the US inventory rely upon the use of hypergolic rocket propellants, many of which are toxic to humans. These fuels and oxidizers, such as hydrazine and nitrogen tetroxide have threshold limit values as low as 0.01 PPM. It is essential to provide space workers handling these agents whole body protection as they are universally hazardous not only to the respiratory system, but the skin as well. This paper describes a new method for powering a whole body protective garment to assure the safety of ground servicing crews. A new technology has been developed through the small business innovative research program at the Kennedy Space Center. Currently, liquid air is used in the environmental control unit (ECU) that powers the propellant handlers suit (PHE). However, liquid air exhibits problems with attitude dependence, oxygen enrichment, and difficulty with reliable quantity measurement. The new technology employs the storage of the supply air as a supercritical gas. This method of air storage overcomes all of three problems above while maintaining high density storage at relatively low vessel pressures (<7000 kPa or approximately 1000 psi). A one hour prototype ECU was developed and tested to prove the feasibility of this concept. This was upgraded by the design of a larger supercritical dewar capable of holding 7 Kg of air, a supply which provides a 2 hour duration to the PHE. A third version is being developed to test the feasibility of replacing existing air cooling methodology with a liquid cooled garment for relief of heat stress in this warm Florida environment. Testing of the first one hour prototype yielded data comparable to the liquid air powered predecessor, but enjoyed advantages of attitude independence and oxygen level stability. Thermal data revealed heat stress relief at least as good as liquid air supplied units. The application of supercritical air technology to this whole body protective ensemble marked an advancement in the state-of-the-art in personal protective equipment. Not only was long duration environmental control provided, but it was done without a high pressure vessel. The unit met human performance needs for attitude independence, oxygen stability and relief of heat stress. This supercritical air (and oxygen) technology is suggested for microgravity applications in life support such as the Extravehicular Mobility Unit.
Doerr
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Biomedical Engineering, NASA, Kennedy Space Center, FL 32899, USA.
D000328:Adult; D000337:Aerospace Medicine; D000389:Air Conditioning / Q000379:methods*; D001831:Body Temperature; D004867:Equipment Design; D006804:Ergonomics; D017079:Exercise Tolerance; D015386:Hazardous Substances; D018882:Heat Stress Disorders; D006801:Humans; D006834:Hydrazines; D008021:Life Support Systems / Q000295:instrumentation*; D008297:Male; D008875:Middle Aged; D009589:Nitrogen Oxides; D016273:Occupational Exposure; D011481:Protective Clothing; D018531:Spacecraft / Q000295:instrumentation*
D015386:Hazardous Substances; D006834:Hydrazines; D009589:Nitrogen Oxides; C029424:hydrazine; C015167:nitrogen tetroxide