Surfactants
Case Studies
Digital Equipment Corporation (DEC) has replaced CFC cleaning systems at its Colorado Springs, Colorado and
Kaufbeuren, Bavaria, Germany facilities. The alkaline aqueous system it installed at these locations consists of
one cleaning, three rinsing, and two drying stations. The cleaning station consists of a heated ultrasonic tank
filled with an alkaline detergent-surfactant. Cleaning is followed by a rough spray rinse, immersion in a high
purity water ultrasonic tank, and finally a spray rinse with high purity water. Drying is accomplished in two
stages. First, excess water is blown off the parts using pressurized clean, dry air. Infrared radiation then heats the
parts surface to 160 F to speed up evaporative drying. The system incorporates a water purification and
reclamation system. Waste water is nonhazardous and can be sent directly to sewer, provided the parts being
cleaned contain no hazardous contaminant. The aqueous system surpasses the CFC system in removing
particulates and is at least equal to the CFC system in overall efficiency.
Vosper, Fred C. and Vickers, David J. Developing Precision Aqueous Cleaning of Hard-Disk Electromechanical
Components, Microcontamination, 10(10): 31-34, 1992.
The Eaton Corporation of Spencer, Iowa, produces hydrostatic transmissions for heavy- and light-duty offroad
use. Four large vapor degreasers required the purchase of 25,000 gallons of TCA annually. They could not find a
suitable aqueous alternative for cleaning the oil-based lapping compound that was a major contaminant. Switching
to a water-miscible lapping compound solved this problem. Eaton now uses a low-pressure spray cleaner for many
of its parts. Cleaners and inhibitors are constantly being evaluated as new chemistries emerge. One Eaton
representative estimates that chlorinated solvent use has been reduced by 99% since 1987.
Alternatives to Solvents (Degreasing for the '90s, Solid and Hazardous Waste Education Center, University of
Wisconsin-Extension, Madison, WI.
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