High Pressure Sprays
Case Studies
SAAB, a Swedish automobile manufacturer, uses a high-pressure cold water spray to clean aluminum engine
cylinder heads after machining. No detergent additives are used to aid cleaning. The water does contain a small
amount of corrosion inhibitor. The water is filtered and reused. The water is pressurized to 4,000 psig and exits
the nozzles at 500 mph. The cleaning system produces one clean, dry cylinder head every 48 sec.
Cold Water Cleans Machined Parts, Tooling & Production, pp. 38-39, June 1989.
Seagate Technology's Normandale facility manufactures read/write heads to be used in disc drives. Trays and
machine tooling are now cleaned using high-pressure deionized water, followed by hot air drying. This change in
cleaning saves over $130,000 annually in CFC-113 costs and reduces the CFC-113 discharge by about 23,000 lb.
Total capital cost to implement the aqueous system was roughly $100,000.
O'Keefe, Gene. Partial Elimination of CFC-113 Usage with the Use of Aqueous Cleaning at the Normandale
Facility of Seagate Technology, Application for the 1992 Governor's Awards of Excellence, Provided by
Minnesota Technical Assistance Program (MnTAP), Minneapolis, MN.
The Northwest Airlines Atlanta Maintenance Base is using high-pressure
water to remove the plasma coating from Pratt and Whitney JT8D turbofan
engine components. Previous methods involved premachining, abrasive
blasting, and chemical stripping. Using the high-pressure (20,000 to
55,000 psig) spray, 100% of the outer ceramic coating is removed. The
spray removes approximately 85% of the thermal barrier bond coat. Final
cleaning of the components still utilizes a chemical stripping solution.
Benefits include:
- Much faster (50-85%) removal of the plasma coating.
- Fewer parts are "out of round" than from the previous method.
- Elimination of 1,000 lb/month of aluminum oxide waste.
- Doubled the useful life of the thermal barrier strip solution.
- Eliminated a 700-gallon cyanide strip solution entirely.
- Low water consumption, approximately 2 gal/min during cleaning.
- Increased service life of the components due to minimal base metal
removal during cleaning.
Keene, Richard. 1992. Plasma Coating Removal via High Pressure Water
Stripping at Northwest Airlines Atlanta Maintenance Base, presented at
the 13th AESF/EPA Conference on Environmental Control for the Surface
Finishing Industry, Orlando, Florida.
Ilco Unican Corporation in Rocky Mount, NC, manufactures 1.5 million metal key blanks daily. Cutting oil and
fine metal chips must be removed before the blank keys can be shipped. Ilco Unican spent $120,000 to purchase
a new high-pressure hot water spray cleaner to replace a 1,1,1-trichloroethane (TCA) vapor degreaser. The new
system uses recirculated hot water sprayed under high pressure to clean the blank keys followed by compressed air
drying. Cutting oil removed from the keys is skimmed during recirculation of the water. Water consumption is 25
gal/d. The water cleaning system has reduced energy consumption by 95% and eliminated the annual consumption
of 200,000 lb of TCA. Ilco Unican has calculated the payback period for their investment at 1.08 years.
Wells, Brian. 1992. Parts Washing With Water Eliminates Detergents. Focus: Waste Minimization, 13:9. NC
Department of Environment, Health, and Natural Resources, Raleigh, NC.
To clean valve control bodies at Honeywell, Skinner Valve Division, a conveyorized system with high-pressure
sprays is used to remove metal chips and process fluids.
ICOLP Technical Committee. 1991. Alternative for CFC-113 and Methyl Chloroform in Metal Cleaning.
To clean engineering model shop prototype parts, a glove spray box is used to remove water-soluble and
solvent-soluble lubricants from parts. A hand-held spray wand is used at 400 psi and 2.5 gal/min. Process uses a
"solvent assisted alkaline cleaner." System cost was less than $5,000.
ICOLP Technical Committee. 1991. Alternative for CFC-113 and Methyl Chloroform in Metal Cleaning.
The 3M plant in Hilden, West Germany, was losing 110 tons of cleaning solvent annually in cleaning two
300-gallon coating tanks. The tanks were cleaned between each color change of coating by flushing and manual
brushing. An outside processor charged 3M for reclaiming the solvent. The tank cleaning process required 800
labor hours/yr and used a lot of solvent. 3M switched to a portable high-pressure spray head for cleaning the
tanks, which incorporates a solvent recovery system. The new high-pressure system does a better job of cleaning
the tanks and requires significantly fewer manhours annually. The cost of the new system was $69,000. The
Hilden plant saved $61,500 the first year in solvent and labor costs. Prior to the change, it took one employee 3
hours to clean one tank. With the new system, it takes one employee 5 minutes to insert the spray head and 10
to 20 minutes to clean the tank. An added benefit of the high-pressure spray head is less worker exposure to the
cleaning solvent.
3M Company. Tank Laved, Solvent Saved, Toil Shaved. Environmental Engineering and Pollution Control
Dept., Saint Paul, MN.
The 3M plant in Cordova, Illinois, contains dozens of 4,000- to 8,000- gallon reactors that are used in the
production of various polymers, adhesives, and resins. Cleaning a reactor used to entail filling it with caustic or
solvent and boiling the solution for 1 or 2 days. Obviously this method used enormous amounts of cleaning
solution and required significant downtime. A team of plant personnel developed and implemented a new cleaning
system that utilizes a rotating high- pressure spray head. Sonic waves generated during the spraying enhance the
properties of the cleaning solution. Cleaning a reactor now consists of spraying 5 gallons of stripper solution at
low pressure, followed by either 300 gallons of caustic solution or 100 gallons of solvent at 600 psig. The cost to
convert to the new system was $36,000. The plant saved $575,000 the first year in materials, labor, and
machine costs. Additionally, the plant eliminated 1,000 ton/yr of water pollutants.
3M Company, Cordova Doozy Kings Do Saving Things. Environmental Engineering and Pollution Control
Dept., Saint Paul, MN.
Washington Scientific Industries (WSI) is a precision machining company which had been using TCA vapor
degreasers at 20 work stations. Initially one aqueous cleaning system using a mild alkaline detergent with a rust
inhibitor sprayed at high-pressure was put into service. This unit replaced one vapor degreaser, which required the
purchase of 1,000 gallons of TCA annually and generated 200 gallons of waste. The cost was $7,000 and the first
year's savings were $6,500. Subsequently, other workstations have been switched to high-pressure aqueous
cleaning.
DeWahl, Karl and Donna Peterson. 1992. Waste Reduction in Solvent Cleaning; Process Changes Versus
Recycling. Pollution Prevention Review, Winter:76-77.
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.
AT&T has reduced its usage of CFC-113 by switching to a semi-aqueous chemistry for cleaning surface mount
assemblies. Parts are fed by conveyor into a power washer consisting of wash and rinse/dry modules. Low and high
pressure sprays of a terpene cleaner are followed by nitrogen knives which reduce cleaning solution dragout and
blanket the washer with an inert atmosphere. In the second module, the parts are rinsed with low, then high
pressure water sprays to remove the terpene cleaner. Rinsing is followed by water removal by air knives within
the same module. Care must be taken in selecting surface mount components because the terpene cleaner swells
some plastics and elastomers. AT&T has found that the new cleaning method is more economical than the
previous CFC-113 method.
Terpene Cleaning of Surface Mount Assemblies, Aqueous and Semi-Aqueous Alternatives for CFC-113 and
Methyl Chloroform Cleaning of Printed Circuit Board Assemblies, EPA/400/1-91/016, June 1991, pp. 51-60.
DuPont Chambers Works of Deepwater, NJ achieved a 98% reduction in a waste stream generated by washing a
process vessel with a flammable solvent. The DuPont Chambers Works site produces several grades of polymer.
During processing polymer accumulates on the vessel walls, agitator blades, and baffles. Opening the vessel for
cleaning is difficult and time-consuming. In December 1991, the solvent was replaced by a high-pressure water
jet. The spray system consists of a special nozzle and lance connected to a high pressure water source (10,000 psi
at 16 gal/min) inserted through a flange at the bottom of the vessel.
This change reduces the incinerated hazardous waste load from .013 lbs/ lb of polymer product to 0.0001 lbs of
non-hazardous waste per pound of polymer produced. Barriers to implementation of the high-pressure spray
included concerns over safety. The system had to be designed to operate remotely and to completely enclose the
water jet. A specialized nozzle is used to reach all interior spaces. This system has been fully implemented.
Capital costs: $125,000. Net present value (EPA method) is $2,720,000 at a 12 percent discount rate; internal
rate of return is 181 percent.
Case Study #: 115. DuPont Chambers Works, Deepwater, NJ. 08203.
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