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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
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
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
"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
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
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
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,"
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
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
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
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,"
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 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,
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,"
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
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
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 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."
|Guide to improving cleaning with Aqueous
The U.S. Environmental Protection Agency (EPA)
has provided some tips on improving cleaning capabilities when
using spray and jet washers. Some of these include:
Switch to detergent-based cleaners.
Many shops are switching from solvent or caustic-based cleaners
to less hazardous detergent-based cleaners. Operators should check
that the type of cleaner used consists of surfactants that are
good detergents but are poor emulsifiers (stable oil emulsions
limit reuse of the cleaner and hasten its disposal). Agitation
of the bath from the jet sprays helps keep the solids in suspension.
Maintain solution quality.
Analytical checks of solution strength, performed by an operator
using simple titration techniques, should be made routinely. The
correction of strength by making small and frequent additions
is more effective than making a few large additions.
Maintain equipment in good working order.
Rack systems should be maintained in good condition, free of rust,
cracks and corrosion which could flake off and contaminate the
bath. Metal tanks should be properly coated with protective finishes
on the inside. Spray nozzles should be inspected regularly to
Screen solids before they reach the waste
sump. The majority of the heavy
metal residue, oil and grease removed from the reservoir occurs
after the actual hot use. Contact equipment manufacturers on options
available for removing solids from the aqueous solution.
Environmental Training and Compliance Tools
Environmental Development Corp. (EDC), Findlay, OH, has developed
Environmental Protection Agency (EPA) and Occupational Safety
and Health Administration (OSHA) training and compliance tools
for the automotive service, including a series of environmental
and safety videos.
'1998 Environmental Guidebook for Automotive
Service & Refueling Operations - covers more than 100
topics on stormwater, vehicle and parts washing, stormwater, oil-water
separators, solid wastes, hazardous wastes, solvents and other
automotive-related issues. The 350-page publication also has a
section on OSHA in the shop, and Environmental Resources Directory
that lists EPA and OSHA federal and state offices and a 37-page
report on environmental enforcement actions.
EPA/OSHA Compliance Audit System for
Automotive Service/Refueling Facilities helps shops gauge their
level of compliance with 500 key environmental/safety questions.
EPA/OSHA training videos for automotive
service. More than 25 EPA and OSHA training videos include an
overview of recommended practices for maintenance shop operations,
environmental aspects of inground automotive lifts and facility-level
For more information contact Environmental
Development Corp. at 419-422-1200 or e-mail email@example.com.