Published: Nov 2012
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A study was performed to characterize the cleanliness level achievable when using a rudimentary cleaning process, and results were compared to JPR 5322.1G Level 300A. While it is not ideal to clean in a shop environment, some situations (e.g., field combat operations) require oxygen system hardware to be maintained and cleaned to prevent a fire hazard, even though it cannot be sent back to a precision cleaning facility. This study measured the effectiveness of basic shop cleaning. Initially, three items representing parts of an oxygen system with maximum operating pressure of 2000 psi were contaminated: a metal plate, valve body, and metal oxygen bottle. The contaminants chosen were representative of materials that could contaminate the system during normal use: oil, lubricant, metal shavings/powder, sand, finger-prints, tape, lip balm, and hand lotion. The cleaning process used hot water, soap, various brushes, gaseous nitrogen, a water nozzle, plastic trays, scouring pads, and a controlled shop environment. Test subjects were classified into three groups: technical professionals having an appreciation for oxygen hazards; professional precision cleaners; and a group with no previous professional knowledge of oxygen or precision cleaning. Three test subjects were in each group, and each was provided with standard cleaning equipment, a cleaning procedure, and one of each of the three test items to clean. The results indicated that the achievable cleanliness level was independent of the technical knowledge or proficiency of the personnel cleaning the items. Results also showed that achieving a Level 300 particle count was more difficult than achieving a Level A nonvolatile residue amount.
precision cleaning, rudimentary cleaning, Level 300, oxygen systems, hardware cleaning procedures, process, non-cleanroom, field shop environment
Piña Arpin, Christina Y.
Component Services Project Engineer, Technical Services Office, NASA Johnson Space Center White Sands Test Facility, Las Cruces, New Mexico
Oxygen Group Project Manager, Materials and Components Laboratories Office, NASA Johnson Space Center White Sands Test Facility, Las Cruces, New Mexico