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DEMONSTRATION OF A LIQUID CARBON DIOXIDE PROCESS FOR CLEANING METAL PARTS
Citation:
Hill, E. AND K. Monroe. DEMONSTRATION OF A LIQUID CARBON DIOXIDE PROCESS FOR CLEANING METAL PARTS. U.S. Environmental Protection Agency, Washington, D.C., EPA/600/R-96/131 (NTIS 97-121149), 1996.
Impact/Purpose:
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Description:
The report gives results of a demonstration of liquid carbon dioxide (LCO2) as an alternative to chlorinated solvents for cleaning metal parts. It describes the LCO2 process, the parts tested, the contaminants removed, and results from preliminary laboratory testing and on-site demonstration at the Air Force Logistics Center (ALC) at Robbins Air Force Base (RAFB), Georgia. The objective of this project was to find and demonstrate innovative parts cleaning technologies to replace environmentally damaging chemicals with more benign processes. The process chosen to be replaced was vapor degreasing in 1,1,1-trichloroethane (TCA), a solvent that is ozone-depleting, a hazardous air pollutant, and one of the 17 chemicals on the Environmental Protection Agency (EPA) 33/50 list of priority pollutants. Carbon dioxide (CO2) degreasing was chosen for demonstration as a potential alternative to TCA because it is noncombustible, nontoxic, listed on the EPA Significant New Alternatives Program list of approved cleaning alternatives, and not ozone depleting. Liquid CO2 is distinct from the better known supercritical CO2 because it can be maintained at lower pressures and temperatures than supercritical, so the cleaning equipment may be less expensive. Both liquid and supercritical CO2 have the advantage of permeating into tiny holes like a gas and have good solvency.