HomeBy Hydro Blast, Inc.
Aqueous parts washers are rapidly replacing
solvent cleaning systems and steam cleaners for out-of-frame cleaning of
large parts and engines. The impetus for this arises from employers concerns
about a "hazard- sensitive" workplace, environmental issues, and
significant labor savings by reducing the time needed to clean parts.
By using the right aqueous parts washer, it is
possible to significantly reduce hazardous waste streams and not sacrifice
cleaning performance. Some variables to consider are the spray, action and
temperature, the required cleaning time, the detergent, the rinse, and
wastewater disposal.
The Spray Action
Aqueous cabinet parts washers use a high water
volume spray to clean parts. Parts rotate on turntable and are washed with
jets of hot water from the top, bottom and both sides. Hot water and
detergent, usually heated to 140 to 180° Fahrenheit, quickly raise the temperature of the parts to where dirt,
grease, oils and other contaminates are easily washed away. The hot parts
quickly dry and are ready for repair. The pressure in an aqueous parts washer
is very low compared to pressure washing.
Cleaning Time
Complete diesel engines and large parts can be
washed without removing most accessories (blowers, fan, turbo, pumps etc.) in
larger aqueous parts washers. Blocks take approximately 15 to 30 minutes to
thoroughly clean. After the block is cleaned and drying, accessories are
washed usually in 5 to 15 minutes, depending on the level of contamination.
In smaller aqueous parts washers, small parts and accessories must be removed
and cleaned separately in a parts basket. They should not be cleaned with the
block and head.
Due to the weight of
diesel engines and related components and large parts, the parts are usually
loaded into an aqueous parts washer using a crane. An overhead loading door
is standard on all Hydro-Blast cabinet style parts washers.
The Detergent
Because of the variety of
metals (cast iron and aluminum) in diesel engine, an all-metal-safe detergent
is recommended. A high pH soap will give better results on heavy carbon or
baked on oil and grease but will discolor and attack soft metals. All detergents
should contain an anti-foamer and a rust inhibitor.
Rinse
A fresh water rinse cycle
is an option most cabinet parts washer manufacturers offer. The rinse removes
residuals left by the detergent. Usually a rinse cycle is not necessary for
this level of parts cleaning because re-machining or final hand cleaning of
cylinder bores or other critical areas may be required.
Another rinse option is to
use a 2-gpm/1000 PSI pressure washer to rinse the block or engine or parts in
the cabinet. This adds water to the washer and helps maintain a constant
water level.
Wastewater Disposal
· Washwater eventually becomes too contaminated to clean effectively. Most
companies refuse to discharge this waste to the sewer and risk the potential
fines. Recycling the water is an option. However at some point, this water
cannot be recycled further and must be disposed of properly. Evaporation is a
very cost-effective option when compared to having a commercial waste hauler
dispose of the wastewater three to five times a year.
· When wastewater is disposed of through evaporation, oil is removed from
the wastewater using an oil skimmer. It is channeled to an outside reciprocal
for recycling or burning in a waste oil heater. Then the wastewater disposal
system is started by using under floor heating. The wastewater boils until
evaporation is complete. This usually takes eight to twelve hours. The
heaters shut off automatically at the end of the evaporation cycle.
· The steam from evaporation is ducted outside the building with the aid of
a in-line draft inducer. This steam is no different from the steam that
escapes when you open the door at the end of a wash cycle. It is not
hazardous.
· After evaporation is complete, a small quantity of residual solids will
remain on the floor of the cabinet. This sludge is easily removed with a
wet/dry vacuum or scooped up with a dust pan. These residual solids must be
disposed of properly. A certified laboratory can do a Toxicity Characteristic
Leaching Procedure (TCLP) on the solids to determine its contents and
classify it as hazardous or non-hazardous waste. Traditionally the TCLP test
is a one time test and cost when cleaning like parts. Test costs vary from
$180 to $300 depending on the laboratory.
· Evaporation will reduce the weight and volume of a waste stream by as
much 95%. It will also reduce costs for on-site training, handling, storage
and disposal of hazardous wastes and the potential fines associated with
wastewater spills. Evaporation is an effective way to reduce EPA assessments
from a medium generator to a small waste generator.
· A typical diesel repair facility would usually find that the build up in
the bottom of a cabinet parts washer would require wastewater disposal
(evaporation) every three months. Evaporation is recommended when the level
of dirt at the bottom of the cabinet parts washer reaches a depth of about
one inch or the washer is not cleaning properly.
Hazardous Waste and Toxic Reduction Program
Several states have a hazardous waste and toxic
reduction program with specific guidelines that meet or exceed U.S.
Environmental Protection Agency requirements. As an example Technical
Information Memorandum, Number 86-3, published by the Washington State
Department of Ecology, contains information and guidance on how generators
may treat their own dangerous waste(s) on-site, without dangerous waste
treatment permits. The Department of Ecology is actively promoting treatment
by generator for several reasons. Treatment often is preferred to the
disposal of a waste because it may be more environmentally desirable and
economically feasible. You should contact your local agency for
guidelines.
A case example for evaporation would be:
Machine shops that generate large amounts of waste water mixed with spent
caustic solution that test hazardous for lead and corrosively. By using an
evaporator these shops can reduce the quantity of their waste in an
environmentally safe manner.
Summary
Aqueous parts washers clean parts to acceptable levels of cleanliness using detergent and hot water. Besides the cost and labor saving aqueous parts washers offer, evaporation is another cost savings and added environmental advantage. However, one of the best advantages of aqueous parts washers are they can usually pay for themselves in less than one year in labor savings.
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