Low Pressure Sprays (Rotary Spray Washers)
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.
GE Medical Systems of Waukesha, Wisconsin, is a manufacturer of medical diagnostic equipment. Spray cleaning
(degreasing) of parts using TCA resulted in fugitive air emissions. GE Medical Systems eliminated the fugitive
TCA emissions by changing to a terpene cleaner for degreasing. Degreasing with TCA required the purchase of
800 gallons of solvent per year, all of which was lost to atmosphere. The terpene cleaner is much less volatile,
requiring the purchase of only 30 gallons per year. The terpene cleaner is recycled. There was no capital
expenditure required to implement the change in cleaning solution.
Wisconsin Department of Natural Resources. Case Study: GE Medical Systems; Replacing 1,1,1-Trichloroethane
With Citrus-Based Solvents. PUBL-SW-168 92. Hazardous Waste Minimization Program (SW/3). Madison, WI.
Martin Marietta Astronautics has substituted an isopropyl alcohol (IPA) spray for CFC-113 in the second stage
of a two-step cleaning process. The old system had required the purchase of 55,000 lb of CFC-113 annually,
which was released to atmosphere. The IPA spray system has a bath with an inert atmosphere, solvent recovery,
and VOC emission controls. Capital expenditure was $1,300,000. The savings realized amount to $325,000 per
year with zero CFC-113 emissions.
Dykema, Kevin J., and George R. Larsen. 1993. Shifting the Environmental Paradigm at Martin Marietta
Astronautics. Pollution Prevention Review, Spring:202-204.
A decorative plating company switched from perchloroethylene vapor degreasers to an automated aqueous
system. The new system includes an alkaline prewash, spray rinse, alkaline wash, three successive rinses in
deionized water, followed by air-knife blowoff, and finishing with an oven dry. The system was put into operation
in 1991, eliminating perchloroethylene usage.
Willis, Dennis G. 1992. Decorative Plater Eliminates Vapor Degreasers. Capsule Environmental Engineering,
Inc., Presented at the 13th AESF/EPA Conference on Environmental Control for the Surface Finishing Industry,
Orlando, FL, January.
The Eaton Corporation of Spencer, Iowa, produces hydrostatic trans- missions for heavy, and light-duty offroad
use. Four large vapor degreasers required the purchase of 25,000 gallons of TCA annually in addition to the
solvent being reclaimed. They could not find a suit- able 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.
University of Wisconsin-Extension. Alternatives to Solvents (Degreasing for the '90s), Solid and Hazardous Waste
Education Center, Madison, WI.
A steel mill had been cleaning 42 inch roller bearings by boiling them in fuel oil for 6-8 hours in a 300 gallon vat.
This was followed by manually scraping and brushing to remove the high temperature grease used in the bearing.
They installed a spray washer (80 gpm, 75 psi, 160 F) as an alternative. The spray washer cleans the bearing in
15 minutes and gets it cleaner than the old method. The cost of the spray washer was returned to the company in
6 months in labor savings alone. As a result of installing the new washer they are cleaning the bearings more
often (prolonging bearing life), and have eliminated a significant safety hazard.
Nourie, Steven M./American Metal Wash, Inc., Aqueous Clean Does Work, Proceedings of the 1991 International
CFC and Halon Alternatives Conference, Baltimore, MD, pp 61-62.
The rubber, grease, oil, dirt, and carbon that accumulates on non-critical aircraft components and wheels must be
cleaned off before the parts can be inspected. One manufacturer of airplanes and helicopters is now cleaning with
an aqueous spray washer. Previously the cleaning was done with CFC based cleaners, using vapor degreasers,
brushing, or blasting. Switching to the aqueous system has reduced the amount of ozone depleting solvent used by
the manufacturer (some parts still require a solvent wash). Several detergents were tried before one was found
which did not interfere with the dye inspection method.
Nourie, Steven M./American Metal Wash, Inc., Aqueous Clean Does Work, Proceedings of the 1991 International
CFC and Halon Alternatives Conference, Baltimore, MD, pp 62-63.
TRW manufactures electronic assemblies for the space and defense sector in its California plants. RMA flux is
now removed using a semi-aqueous chemistry in a batch spray cleaner. This cleaning method replaces about 90%
of the vapor degreasing with CFC-113. Until 1993, TRW had been using CFC-113 at the rate of 300K lbs/yr.
The new method will use an estimated 20 drums of cleaner per year to replenish 5 semi-aqueous cleaning units.
The current cost of the semi-aqueous cleaner is $250/55 gal drum. In addition to reducing CFC-113 usage by 90%,
with its associated disposal costs, the new semi-aqueous method is producing cleaner electronic assemblies. The
waste SA cleaner qualifies as a fuel blend, lowering disposal costs. Cleaning cycle times have increased due to the
drying required. Because the plants are producing relatively small quantities of high quality components, the
increased cycle time has not been a significant factor.
Hernando E. Arauco/TRW, "CFC Solvent Elimination in ETD", presented at the 1993 Solvent Substitution
Conference, Phoenix, AZ, Dec.93. Hernando E. Arauco/TRW, telephone conversation with K.D. Carter/RTI,
Feb.94
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