United States
Environmental Protection
Agency
Risk Reduction
Engineering Laboratory
Cincinnati, OH 45268
Research and Development
EPA/600/SR-93/223 February 1994
&EPA Project Summary
Ultrasonic Cleaning as a
Replacement for a
Chlorofluorocarbon-Based
System
P. B. Kranz, T. Gardner-Clayson, K. C. Malinowski, T. D. Schaab,
J. E. Stadelmaier, and P. M. Randall
The study summarized here evalu-
ated, on a technical and economic ba-
sis, the replacement of a solvent vapor
degreasing system using chlorofluoro-
carbons (CFC-113) with an ultrasonic
cleaning system using a heated water-
based cleaning fluid for cleaning stain-
less steel parts.
The intent of the substitution was to
reduce fugitive volatile emissions while
eliminating the use and handling of haz-
ardous materials at the facility. The ul-
trasonic cleaning system was custom
fabricated to meet the dimensions re-
quirements of the parts fabricated on
site. Cleaning standards for the new
system were to remain consistent with
the criteria used for vapor degreasing.
Through the utilization of an ultra-
sonic cleaning system, fugitive emis-
sions have been significantly curtailed.
Volatile emissions are estimated to be
reduced 68% (3,450 vs. 10,876 Ib/yr)
over the period 1990 to 1992. This re-
duction was in addition to the elimina-
tion of bench top freon cleaning units
at the facility, which reduced emissions
from 25,215 to 10,876 Ib/yr from 1987
to 1990. The elimination of 26 drums/yr
of still bottoms generated through sol-
vent reclamation was also realized.
To complete the economic evalua-
tion, the costs of raw material (clean-
ers), utilities, and labor was considered
along with waste disposal. An annual
savings, utilizing the ultrasonic clean-
ing system, was projected to be $27,875
with the most significant savings real-
ized with the cost differential in raw
materials because of the high cost of
chlorofluorocarbon cleaning solvents.
A payback period of 1.6 yr was calcu-
lated for the project.
Additional benefits from the emission
reduction include improved working en-
vironment, reduced indoor air pollut-
ants, and better community relations.
This Project Summary was developed
by EPA's Risk Reduction Engineering
Laboratory, Cincinnati, OH, to announce
key findings of the research project
that is fully documented in a separate
report of the same title (see Project
Report ordering information at back).
Introduction
The use of CFCs in vapor degreasing
cleaning systems has been the accepted
standard in various industries for many
years. This process has been universally
accepted because of the efficiency and
ease with which parts are cleaned and
the subsequent compliance with quality
control standards for cleanliness of the
parts or materials cleaned. In recent years,
however, the disadvantages of this tech-
nology have become increasingly appar-
ent — the process' generation of fugitive
emissions resulting in reporting require-
ments under SARA Title III, concerns about
employee health and safety, and increased
cost and taxation of CFCs. Furthermore,
CFCs are targeted for eventual elimina-
tion because of their ozone depleting char-
acteristics.
The project objectives were to evaluate
the technical feasibility, performance, eco-
nomic impact, and reduction of fugitive
volatile emissions resulting from the sub-
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stitution of vapor degreasing with aque-
ous ultrasonic cleaning.
This is a study of the effectiveness and
applicability of ultrasonic cleaning using a
heated water-based cleaner as a means
to clean stainless steel components. An
evaluation was completed under the Erie
County/EPA WRITE Program as a joint
effort by Conax Buffalo Corp., Cheektowaga,
NY; Erie County Environmental Compliance
Services, Buffalo, NY; Recra Environmen-
tal, Inc., Amherst, NY; and the U.S. Envi-
ronmental Protection Agency, Office of
Research and Development, Cincinnati
OH.
Procedure
The industrial participant for this pro-
gram was Conax Buffalo Corporation
(Conax). Conax has been engaged in the
design and manufacture of highly engi-
neered, precision products for industrial,
aerospace, nuclear, fiber optic, and mili-
tary applications. At Conax, stainless steel,
aluminum and copper parts coated with
standard screw oils, water-based coolants,
inhouse shop dirt, and metal shavings are
cleaned in a series of cleaning and rinsing
tanks of modular design using a heated
alkaline solution. Previously, cleaning ac-
tivities involved the use of two types of
freon-based solvents that generated more
than 10,000 Ib of fugitive emissions annu-
ally from two vapor degreasers and two
work bench stations.
Since 1990, chlorinated solvents and
chlorofluorocarbons (CFC-113) including
trichloroethylene, 1,1,1-trichloroethane,
trichlorotrifluoroethane (freon), and a freon/
acetone mixture have been used at Conax.
The CFCs are used for both degreasing
parts after machining, and cleaning parts
prior to assembly, shipment, or stock. Un-
til recently, four operations within Conax
utilized chlorinated solvents and CFCs.
These include machining centers parts
cleaning, machine shop vapor degreasing,
assembly vapor degreasing, and final as-
sembly cleaning.
Because of their ozone depleting char-
acteristics, CFCs are targeted for even-
tual elimination per the 1987 Montreal
Protocol and Clean Air Act. The costs of
CFCs are increasing and the use of CFCs
is going to be taxed. Reclamation of CFCs
generates stillbottoms that are F002 haz-
ardous waste. The ultrasonic parts clean-
ing system was installed to avoid and
eliminate the problems associated with fur-
ther CFC use.
For 2 wk in January 1992, the ultra-
sonic cleaning system was evaluated for
131 batches of parts ranging from large
tubes to pins and from 1 to several thou-
sand parts/batch. Because this was con-
sidered typical production, the results
would be extrapolated to an annual basis.
Average cleaning times and chemical ad-
dition requirements were documented, and
subjective quality control inspections were
done on each batch. Project forms devel-
oped for the project tracked the time in
minutes for each batch at each station in
the cleaning process. Clean and rinse tank
pH was monitored along with the clean
and heated rinse tank temperatures. The
number and description of parts in each
batch were also listed on another project
form. Averages for processing times, pH,
and temperatures were calculated along
with totals for a breakout of batch part
quantities from 1 to 15, 15 to 100, 100 to
1000 and 1000+ parts/batch.
The batches of tubes cleaned during
the monitoring period were totaled. The 8-
ft-long tubes were of particular interest
due to the part configuration. To limit fugi-
tive emissions, the surface area and work-
ing area of the vapor degreasers were
limited. This required a "double dip" pro-
cedure for cleaning the 8-ft-long tubes.
Because of the length of the tubes, this
procedure required an extended period of
CFC use resulting in greater emission gen-
eration. The ultrasonic cleaner was de-
signed to accommodate long tubes in a
"single dip" cleaning operation eliminating
the emissions and facilitating smoother
parts cleaning operation.
The Miraclean* system used by Conax
is designed and manufactured by
Chautauqua Metal Finishing Supply of
Jamestown, NY. It is a modular design of
cleaning and rinsing tanks, employing an
aqueous cleaning agent within the ultra-
sonic tank to accelerate and facilitate the
cleaning action (i.e., cavitation). Miraclean
systems have a variety of available op-
tions such as additional rinse tanks and
dryer station to meet individual customer
needs.
The ultrasonic cleaning system pur-
chased by Conax entails six cleaning sta-
tions (see Figure 1). At Station 1, small
parts were placed in metal baskets for
cleaning. Baskets were required to have
minimal mass, be made of metal, and be
of open construction to limit interference
with the free passage of both sound waves
and cleaning fluids. An overhead crane
was used for larger, more cumbersome
parts.
Station 2, the cleaning tank, contained
six ultrasonic transducers mounted on the
side of the tank. The tank also was de-
signed with an interior grease trap/over-
' Mention of trade names or commercial products does
not constitute endorsement or recommendation for
use.
flow weir and sparger system to remove
insoluble oils and extend bath life.
Stations 3 and 4 are counterflow rinse
tanks. A counterflow rinse was incorpo-
rated to minimize fresh water use. The
rinse tanks diluted the concentration of
cleaner that remained on the part after
cleaning. The first rinse tank, Station 3,
has an overflow weir that collects insoluble
solution that remains on the part.
Station 5 incorporates a final hot rinse
into the system. Heat was added to facili-
tate part drying subsequent to cleaning.
Station 6 provided an area for unload-
ing parts from baskets. An air gun was
provided to facilitate drying of parts with
configurations that tended to retain water
(i.e., dead end tap holes).
Overall dimensions of the Miraclean sys-
tem are 10' x 6.5' x 3' high. Fiberglass
covers were installed to retain heat, con-
serve energy, and reduce evaporation and
humidity in the work area.
Samples of the wash tank (Station 2),
rinse tank (Station 4), and final hot dip
tank (Station 5) were taken to be ana-
lyzed for oil and grease and total organic
carbon. Samples were taken just before
changeout of the wash tank, of the wash
solution after neutralization, and early in
the use of fresh solution to track the con-
centration of organic contaminants in the
system.
Results and Discussion
Historical Background
For comparison purposes, historical in-
formation on fugitive emissions reporting
and hazardous waste generation was ac-
quired from Conax. Fugitive emission data
was collected from Form "R" reports. To-
tals for each are shown in Table 1.
A significant reduction in fugitive emis-
sions is noted from 1987 to 1990 resulting
from the elimination of bench top freon
cleaning units at the machining areas. Fu-
gitive volatile emission reductions from the
1990 efforts also resulted in the elimina-
tion of the Blakslee freon vapor degreasing
unit. The Miraclean system was installed
in August 1991.
A log of cleaning activity was kept for 2
wk during January 1992 (1/13-24/92). En-
gineers at Conax described this 2-wk pe-
riod as typical of production for the facility.
Information was gathered on 131 batches
of parts cleaned during the 2-wk period.
Average time/batch spent in the Miraclean
unit is approximately 8 min. This com-
pared well with the 7 min/cycle for the
vapor degreasers.
Wastes associated with the vapor
degreasing units included emissions and
stillbottoms estimated at 26 drums/yr and
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Station Station
6 5
Station
4
Station
3
Station
2
Station
1
Fresh '
Water Feed
\
\
Parts
\ Rinse Water
To Drain
Hot Rinse Tank
180°F
Second
Counterflow
Rinse Tank
Ambient T"
First
Counterflow
Rinse Tank
Ambient T°
Ultrasonic Clean
Tank
150-180°F
Figure 1. Conax's Miraclean System Schematic.
Table 1. Historical and Projected Emissions and Waste Generation
Year
1987
1988
1989
1990
199r
1992f
Fugitive Emissions
(Ib)
25,215
32,990
12,819
10,876
6,900
3,450
Hazardous Waste
(Ib)
2,670
1,290
4,400
1,595
1,890
1,380
" Estimated for remainder of 1991.
* Projected lor 1992.
1,134,000 million gal/yr of non-contact
cooling water. The water-based cleaning
medium used in the Miraclean system gen-
erated an estimated 1050 Ib/yr of waste
that, subsequent to neutralization, could
be sewered along with the 567,000 gal/yr
of rinsewater. Approximately 55 gal/yr (450
Ib) of oil collected by the ultrasonic clean-
ing process was sent for fuel blending.
Fugitive Emission Reduction
Emissions generated at Conax origi-
nated from cleaning operation at the ma-
chining centers, the assembly tables, and
the Blakslee vapor degreaser. The elimi-
nation of CFC use at the machining cen-
ters by substituting aqueous cleaners into
the bench top ultrasonic cleaning units
reduced emissions by 14,500 Ib/yr over a
period from 1987 to 1990.
The elimination of the Blakslee vapor
degreaser further reduced emissions to a
projected total of 3,450 Ib/yr for 1992, a
reduction of 68% from 1990. Total volatile
emission reduction projections, from 1987
to 1992, are 86% from 25,215 to 3,450 Ib/
yr resulting from the two operational
changes.
Economic Analysis
An economic analysis of the changeover
from CFC vapor degreasing using the
Blakslee unit to the Miraclean ultrasonic
system utilizing an aqueous-based clean-
ing solution is included as part of the
project.
Fixed and variable costs have been con-
sidered as part of the evaluation. Fixed
costs include the cost for equipment and
installation of the Miraclean system. These
costs include the ultrasonic equipment,
NEMA enclosure, three tank system,
pumps, filter, sparger pump, tank covers,
overhead crane, supplies, and labor.
Variable costs included in the economic
assessment were raw materials, power
costs, sewer fees, off-site disposal, water
costs, and labor. Raw material cost was
determined using 1990 cost data and ma-
terial use supplied by Conax. Labor cost
was estimated using $15/hr as a basis.
Sewer fees and water cost information
was supplied by Conax. Total operating
costs were determined as a summation of
variable costs.
A total operating cost/batch of parts
cleaned was also determined for compari-
son.
Based on these costs, annual savings
and a payback period for the new
Miraclean system were calculated for the
project.
The total fixed costs for the Miraclean
system according to information provided
by Conax was $44,411. Variables costs
calculated for the two systems are listed
in Table 2.
Annual savings projected using the
aqueous ultrasonic system was calculated
to be $27,178. This resulted in a per batch
savings of $7.94 ($7.26/batch vs. $15.20/
batch for vapor degreasing). A payback
period for the system using the savings
calculated and reported total costs was
determined to be 1.6 yr.
As the cost for the use of CFCs con-
tinue to increase as anticipated, the im-
pact to the economics associated with the
substitution of ultrasonic aqueous clean-
ing would be even more favorable.
Conclusions
With the installation of an ultrasonic parts
cleaning unit utilizing water-based clean-
ers, the elimination of vapor degreasing
using solvent-based cleaners is possible
without impacting cleaning quality. A re-
duction in the generation of fugitive emis-
sions and hazardous waste associated with
a vapor degreaser is realized along with
cost savings.
The quality of the cleaning realized by
Conax as a result of the changeover is as
good, or in some cases, better than with
vapor degreasing. Freon-cleaned products
would, at times, have a slight powder resi-
due deposition after drying. This is be-
cause of the inability of solvents to dissolve
inorganic salts that accumulate on the
parts. No such problem was encountered
with the Miraclean system. At no time
during the evaluation were parts returned
for recleaning by Conax's inhouse quality
assurance or assembly departments.
Freon use was reduced by approxi-
mately 77% (1990 to 1992). Annual waste
reduction realized was over 12,000 Ib when
fugitive emissions are included. Transport
&U.S. GOVERNMENT PUNTING OFFICE: MM - 5M4C7/MIM
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and fate of wastes changed from pre-
dominantly uncontrolled air emissions of
freon to predominantly cutting and clean-
ing rinsewaters that can be sewered and
treated by the local public wastewater treat-
ment facility.
Table 2. Variable Costs
Freon Vapor
Degreaser
($)
Utility Costs
Labor Costs
Raw Material Costs
Water Costs
Sewer Costs
Off-Site Disposal
Total Operating Costs
1,559
8,205
33,939
1,780
6,200
370
52,053
An annual cost savings of $27,178 was
calculated and results primarily from a re-
duction in raw material costs, a savings
that is anticipated to become more signifi-
cant over time. This savings provides a
1.6 yr payback period for the project.
Aqueous Ultrasonic
Cleaning System
($)
8,087
8,295
1,203
890
6,200
200
24,875
The benefits realized by Conax as a
result of the replacement of the solvent
vapor degreaser with an ultrasonic water-
based cleaning system include reduced
fugitive emissions; reduced hazardous ma-
terial handling and waste generation; and
improved cleaning efficiency, working en-
vironment, and community relations. The
results of this evaluation conclude that
ultrasonic cleaning using water-based
cleaners provides a viable and economi-
cally advantageous alternative to the prob-
lems associated with solvent vapor
degreasing.
The full report was submitted in fulfill-
ment of CR-816762-02-0 by Erie County
Department of Environment and Planning
under the sponsorship of the U.S. Envi-
ronmental Protection Agency.
P. B. Kranz is with Erie County Department of Environment and Planning, Buffalo,
NY 14202; T. Gardner-Clayson, K.C. Malinowski, T.D. Schaab, andJ.E.
Stadelmaier are with Recra Environmental, Inc., Amherst, NY 14228; and
Paul M. Randall (also the EPA Project Officer, see below) is with the Risk
Reduction Engineering Laboratory, Cincinnati, OH, 45268
The complete report, entitled "Ultrasonic Cleaning as a Replacement for a Chloro-
fluorocarbon-BasedSystem," (Order No. PB94-121 696/AS; Cost: $27.00, subject
to change) will be available only from:
National Technical Information Service
5285 Port Royal Road
Springfield, VA 22161
Telephone: 703-487-4650
The EPA Project Officer can be contacted at:
Risk Reduction Engineering Laboratory
U.S. Environmental Protection Agency
Cincinnati, OH 45268
United States
Environmental Protection Agency
Center for Environmental Research Information
Cincinnati, OH 45268
Official Business
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