Selection of Low Ozone Depleting Oxygen System Cleaning Solvents

摘要

CFC113 (1,1,2-trichlorotrifluoroethane) was widely used in the military for removing dirt and lubricants from equipment. Users sought substitute "environmentally friendly" solvents due to banning of the ozone-depleting compounds. In this work, for wipe and liquid cleaning of liquid and gaseous oxygen systems, seven solvents, plus CFC113 as a baseline, were evaluated as CFC113 replacements. First, the cleaning ability was evaluated with common military lubricants and other common contaminants anticipated to be found on oxygen system components, MIL-PRF-7808 (ester-based gas turbine engine oil), MIL-PRF-83282 (hydraulic fluid), MIL-PRF-27617 (perfluoropolyalkylether-based PTFE thickened grease), MIL-PRF-27617 sprinkled with Arizona road dust, SAE 20W-50 tube bending oil, and 3M 250 tape residue. These solvents were also tested for compatibility with oxygen systems using the liquid oxygen mechanical impact test and by determining the autogenous ignition temperature in pure oxygen. Candidate solvents must also be compatible with elastomer seals. None of the solvents caused permanent damage to the seals. No single solvent performed as well as nor was as universal as CFC113 but several were close.