Supercritical Fluids
Case Studies
The United States Air Force Materiel Command at Newark AFB, Ohio, maintains inertial guidance and
navigation systems. Various metals, plastics, and epoxies are subject to precision cleaning on the base. Prior to
1988 the Aerospace Guidance and Metrology Center was using 2,000,000 lb of CFC-113 annually. Small
quantities of methyl chloroform, CFC-12, and trichloroethylene were also being used. Several changes were
instituted to reduce/eliminate CFC usage at the base. Installation of centralized aqueous precision cleaning centers
eliminated nearly all the vapor degreasers on base. Additionally they are using air and nitrogen for cooling,
supercritical CO2, perfluorocarbon flushing, and fluorocarbon/surfactant blends for cleaning. Payback on new
equipment cost is about 2 years. The Aerospace and Guidance Center anticipates that it will have a 90% reduction
in ozone-depleting solvents by October 1993.
Hunt, Don. 1992. How One of the Largest Air Force Users Is Getting Out of CFC'S, Proceedings of the 1992
International CFC and Halon Alternatives Conference, pp. 547-556.
A defense contractor in Boston, MA uses supercritical CO2 to clean gyroscope parts. The parts are contaminated
with machining coolants, silicone oils, and damping fluids. The contractor has found that supercritical CO2 works
well for parts with complex shapes. Previously, cleaning was done in a vapor degreaser.
Weber, David, Precision Parts Cleaning with Supercritical Carbon Dioxide, CF Technologies, One Westinghouse
Plaza, Hyde Park, MA 02136, 617-364-2500.
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