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Cleaning With Jet Spray Washers: Replacing Solvent Cleaning Processes With Aqueous Cleaning.

By Ed Sunkin

As more environmental regulations phase out many chlorinated solvents and ozone depleting chemicals, many automotive machine shops and engine rebuilding operations are replacing their solvent cleaning processes with aqueous cleaning. Some argue that while replacement chemicals have been found, their total safety and part cleaning applicability has not been researched enough. According to many rebuilders and equipment makers, developments in aqueous cleaning equipment have yielded equal to or even better results in cleanliness testing compared to the solvent-based processes.

Spraywashers and detergent-based jet parts washers are much like a home "dish washers', the combination of the cleaning solutions detergency, heat, and the physical scouring action of the jet spray is what cleans a part in a jet spray detergent washer.

Bill Wessle, of Kansas Instruments, Council Grove, KS, explained spraywashers were being developed as early as the mid 1970s as an alternative to the traditional cleaning methods that utilize either caustics, natural solvents, or petroleum-based solvents. Wessel said cleaning parts with caustics typically required hours of soaking, as well as brushing and scrubbing the large parts. "The design of spraywashers developed from the idea of becoming more labor conscious in the shop. Spraywashers can clean parts a lot faster than the hot-tank method," Wessel said.

Wessel said spray washing is a popular technique to clean parts with large surfaces like cylinder heads, engine blocks and transmission housings because the spraywasher directs streams of solution through high pressure nozzles to dislodge dirt and grime from the metal's surface. Contaminates are washed away by the chemical action of the detergent or cleaning solution along with the force of the liquid hitting the component surface.

Wessel said a reason why shops are moving to jet spray washers may be because shop managers have noted dramatic employee productivity increases with the imposition of the new cleaning technologies.

"With traditional cleaning methods, it may have required and employee a couple of hours of brushing and scouring with solvents before a part would be clean," Wessel said. "With jet spray washers, cleaning time is used more efficiently since no brushing, scouring or soaking is usually necessary. You simply load the parts into the machine, push a button, go do something else, and in about 15 minutes your parts are clean."

Most jet spraywasher manufacturers suggested cleaning cycle times range anywhere from 10 minutes to 30 minutes, depending on the load and how dirty the parts. Since the parts rotate on a turntable as they are washed, spray washing usually eliminates the need for additional scrubbing, scraping or brushing following the wash cycle, thereby saving time and labor, as well as exposure to potentially harmful or toxic caustics and solvents which present occupational risks to employees. Caustics can severely burn technicians and solvents are typically carcinogenic, flammable or combustible. All are typically considered hazardous wastes when spent and are required to be disposed according to strict guidelines.

Mark Adams, national marketing manager for Hydro-Blast, Inc., Vancouver, WA, said many shops today are turning to aqueous cleaning because of the paperwork, management requirements, and training imposed by the EPA and OSHA when using hazardous caustic and solvents to clean parts, as well as from the large amounts of hazardous waste solvent cleaning generates. "In these environmentally conscious times, aqueous parts washers are replacing several types of existing systems," Adams said. "We're seeing a lot of companies switch from cleaning with solvent and corrosive chemicals to aqueous cleaning. The EPA has established a deadline for the elimination of several solvent alternatives because many are considered hazardous air pollutants, ozone depleting and present safety concerns such as flammability or human toxicity."

Basically, there are three general styles of cabinet washers - front load, top load and pass-through conveyer systems. Each style basically has the same components - a turntable or conveyer, spray bars with jets or nozzles, a pump to spray the parts with a cleaning solution, drive motors, a heat source, timers and thermostats.

Accessories like oil skimmers, coalescers, or weirs, filtration, and sludge dryers or solids flocculating mechanisms are becoming more and more standard as the technology evolves.

But it's these accessories that have made the rebuilder's job a little easier, according to Kent Whelen of Sunnen Products Co., St. Louis, MO. "Things like seven-day timers which automatically pre-heats cleaning solutions before the start of each day or shift and then shuts down after each shift is very handy for the rebuilder, " Whelen said. "The equipment is ready to go when the emplyees are."

Hydro-Blast's Adams said accessories like filters and coalescing plates can extend the useful life of the cleaning solution, saving the rebuilder money. "However, the wash water will eventually become so dirty that parts no longer clean properly and the wash water will need to be disposed of," Adams said.

For more information on reducing wastes generated from cleaning, refer to Automotive Rebuilder's December 1997 feature "Waste Minimization Options."

Adams said there are several factors that will affect the cleaning ability of an aqueous parts washer, the chemical, the temperature of the wash water and the cleaning time. "Many types of cleaning chemicals are available from high pH sodium hydroxide based for ferrous materials, to mid pH "all metal safe" solutions for most metal types including aluminum, citrus-based and light acids for phosphotizing," said Adams, who suggested shops should look for cleaning solutions that contain a rust inhibitor and defoamer added to them.

Delores Shaver, industrial sales manager for Ecolink, Stone Mountain, GA, a manufacturer of environmentally preferred solvents used in jet washers, said there are important issues for rebuilders who are buying a parts washer to be aware of. "Ask the manufacturer a lot of questions about what cleaning solutions can be used in their washer. Some solutions are not recommended for certain cleaning equipment," Shaver said. "Some solutions will deteriorate the equipment's hoses or seals, so buy a parts washer that you know can accommodate the cleaning solution your work requires."

Shaver said there are a lot more environmentally preferred cleaning agents available for the rebuilder today. And switching to detergent-based jet washing system usually reduces hazardous waste generation, and in certain cases, eliminates some regulatory burdens.

She said the use of general purpose cleaners that have not been formulated specifically for this purpose is not recommended and may lack anti-foam agents or corrosion inhibitors, and may emulsify oils. This may result in a shop full of suds, shortened life of your jet washer, or the generation of more sludge than necessary.

Kansas Instrument's Wessel said jet washers are used normally for three different types of cleaning in the machine shop. Some large shops will use spraywashers as a pre-cleaning operation. Pre-cleaning of parts is often done with a large, conveyer-type spraywashers.

A second type of cleaning is referred to as general cleaning. Scott Murray, who operates the one-man machine shop at Murray's Auto Parts, Lancaster, OH, said he usually operates the shop's spraywasher about three or four cycle-times a day, at about 30-minutes per cycle. Murray said the spraywasher is filled with an aqueous aluminum-safe cleaner. "I use it mostly for primary cleaning of aluminum heads and for small parts," Murray said, adding it's important not to use a caustic cleaner that's acceptable for cast iron on aluminum parts. "A caustic cleaner will etch aluminum and turn it a black-color," Murray said. "In order to keep from having to change the solution, I'll normally just use the spraywasher for aluminum parts."

According to one chemical supplier, aluminum-safe detergents should have a medium pH rating (10 to 12) and contain silicates to protect the metal against corrosion.

A third common use of spraywashers is for final cleaning of engine parts after they have been machined to remove any metal pieces or oils from honing. Doug Anderson, vice president of Grooms Engines, Parts, Machining, Inc., Nashville, TN, said final cleaning of engine parts with spraywashers is common for large rebuilder shops like his. "We have three jet spray washers that are used for various final cleaning operations," Anderson said.

Murray said he also uses the shop's spraywasher for a final cleaning of machining heads and blocks. But this versatile piece of shop equipment can be used for more than just engine parts. "I may have some manifolds or real greasy rear axles that will need cleaned up, so I'll use it then, too," Murray said. "In fact, I use a spraywasher on a lot of components."

And spraywashers in machine shops have also been utilized for non-traditional jobs. Jim Wright, owner of Motor Heads, Elyria, OH, said taking on non-traditional work is a way to bring in extra money into his shop, "We use our spraywashers to clean the filters that are installed above the fryers and grills in restaurants," Wright said. "We clean a lot of these filters for nearby restaurants."

Costs

Costs associated with the base-jet washer technology are similar to other equipment purchases in the shop. Costs may include capital outlay for equipment, shipping, installation (typically requires electrical work), employee training, lost productivity of employees during transition period, energy (electricity or gas), detergent, water, waste oil disposal, sludge disposal, labor, and repairs.

Greg Myers of Steelabrator Cleaning Systems, San Antonio, TX, said jet spray cleaning equipment is relatively inexpensive to operate. "To clean four heads or an engine block can cost as little as pennies per cycle, depending on your consumables like heating utilities and cleaning solutions," Myers said.

The temperature of the wash will vary between the type of part being cleaned. For spraywashing cast iron, recommended cleaning temperatures are about 200°F. Aluminum parts are typically cleaned about 160° to 180° F, though some rebuilders may operate jet washers as low as 140° to minimize water evaporation losses and energy consumption.

The water is heated electrically or by natural gas or propane. Rebuilders interested in purchasing a jet spray unit should research expected utility costs. Myers said in many parts of the country, heating with natural gas is usually more cost efficient.

However, certain accessories may require additional operating expenditures. For instance, if you purchase a filtration mechanism, you will likely have to service filter membranes, replace or clean filter bags, membranes and liners, and dispose of spent filters as a hazardous waste. This is also the case for chemical flocculating accessories for which you may have to purchase flocculating chemicals and filter liners, and dispose of the increased volume of sludge and filter liners as a hazardous waste.

JC Bianchi of at B & G Machine, Inc., a Seattle, WA-based heavy duty machine shop, said cleaning costs such as wastes handling need to be included in the price of your service to the customer. "Though parts cleaning is usually not a profit center in the shop, I would suggest that for what you pay for cleaning, you should asses reasonable charges for it," said Bianchi. "A lot of shops feel they cannot charge much for cleaning, even though the overall costs are high. But, as with any other cost of operating your business, cleaning expenses must be accounted for."

There are a number of aqueous, jet and spraywasher equipment manufacturers in the market today. When deciding on this or any type of equipment, it is important to check customer references and the stability of the vendor for matters such as technical support and the availability of spare parts. Many vendors have a demonstration facility or can provide on-site training of their equipment. For a list of aqueous and pressure equipment manufacturers, refer to Automotive Rebuilders' January 1998 Automotive/Truck Purchasing Directory.

Bianchi said before purchasing a spraywasher or jet sprayer, make sure it is compatible with your shop layout. "Make sure the doors are convenient and comfortable to use. If they're not, try to put the openings within easy reach," Bianchi said.

Bianchi said this may mean placing the base of the machine under the floor level or securely propping it up. "I've seen shops where the jet washer is placed in the floor so that the loading table is at foot level rather than waist high, and equipment operators seem to love it."