United States
                         Environmental Protection
                                      Risk Reduction
                                      Engineering Laboratory
                                      Cincinnati OH 45268
                         Research and Development
                                      EPA/600/S-92/009 June 1992
               Waste Minimization Assessment for a Manufacturer of
                    Components for Automobile Air Conditioners

                               Gwen P. Looby and F. William Kirsch*
The U.S. Environmental Protection Agency (EPA) has funded
a pilot project to assist small- and medium-size manufacturers
who want to minimize their generation of waste but who lack
the expertise to do so. Waste Minimization Assessment Cen-
ters (WMACs) were established at selected universities and
procedures were adapted from the EPA Waste Minimization
Opportunity Assessment Manual (EPA/625/7-88/003, July 1988).
The WMAC team at the University of Tennessee performed an
assessment at a plant manufacturing charged air coolers, round
tube plate fin (RTPF) condensers, and air conditioner tubes for
automotive air conditioning systems—approximately two mil-
lion  Ib/yr. Even though this plant has three distinct product
manufacturing lines, the processes can be generalized to the
following: initially fins are produced and partially assembled
with various components. These partial assemblies  are vapor
degreased and then either packaged and shipped or brazed
either manually or in a vacuum brazing oven.  Units are as-
sembled  into final products,  painted black, inspected, pack-
aged, and shipped. The team's report, detailing findings and
recommendations, indicated that the majority of waste  was
generated in the rinse tanks and the hot water flush testing
stations but that the  greatest savings could be obtained by
replacing solvent-based vapor degreasing systems with a de-
tergent-based immersion system to eliminate still bottoms and
evaporated solvent losses.

This Research Brief was developed by the principal  investiga-
tors and EPA's Risk Reduction Engineering Laboratory, Cincin-
nati, OH, to announce key findings of an ongoing research
project that  is fully documented in a separate report of the
same title available from the authors.
                         The amount of waste generated by industrial plants has be-
                         come an increasingly costly problem for manufacturers and an
                         additional stress on the environment. One solution to the prob-
                         lem of waste is to reduce or eliminate the waste at its source.

                         University City Science Center (Philadelphia, PA) has begun a
                         pilot project to assist small- and medium-size manufacturers
                         who want to minimize their formation of waste but who lack the
                         in-house expertise to do so. Under agreement with EPA's Risk
                         Reduction Engineering Laboratory, the  Science Center  has
                         established three WMACs.  This  assessment was done by
                         engineering faculty and students at the University of
                         Tennessee's (Knoxville) WMAC. The assessment teams have
                         considerable direct experience with process operations in manu-
                         facturing plants and also have the knowledge and skills needed
                         to minimize waste generation.

                         The waste minimization assessments are done for  small- and
                         medium-size manufacturers at no out-of-pocket cost  to  the
                         client. To qualify for the  assessment, each client must fall
                         within Standard Industrial Classification Code 20-39, have gross
                         annual sales not exceeding $50 million, employ no  more than
                         500 persons, and lack in-house expertise in waste minimiza-

                         The potential benefits of the pilot project include minimization
                         of the amount of waste generated by manufacturers, reduced
                         waste treatment and disposal  costs for participating plants,
                         valuable experience for graduate and undergraduate students
                         who participate in the program, and a  cleaner environment
                         without more regulations and higher costs for manufacturers.

                                                 ra§) Printed on Recycled Paper
'  University City Science Center, Philadelphia, PA 19104

Methodology of Assessments
The waste minimization assessments require several site visits
to each client served. In general, the WMACs follow the proce-
dures  outlined  In the EPA Waste Minimization Opportunity
Assessment Mam/a/(EPA/625/7-88/003, July 1988). The WMAC
staff locates the sources of waste in the plant and identifies the
current disposal or treatment  methods and their  associated
costs.  They then identify and analyze a variety of ways to
reduce or eliminate the waste. Specific measures to achieve
that goal are recommended and the essential supporting tech-
nological and economic  information is developed. Finally, a
confidential report that details the WMAC's findings and recom-
mendations (including cost savings, implementation costs, and
payback times) is prepared for each client.

Plant Background
This plant manufactures components for automobile air condi-
tioners: charged air coolers, round tube plate fin condensers,
and air conditioner tubes. The plant operates  6,240  hr/yr to
produce  approximately two million pounds of automobile air
conditioner components.

Manufacturing Process
Three distinct product components involve three separate manu-
facturing  processes. Each will be described in turn so that the
various operations and their waste-generating capacity can be
kept In perspective.

Charged Air Coolers
Sand-cast aluminum tanks are cleaned in an aqueous alkaline
bath at 160°F  and then water-rinsed  in  successive stages
before being air-dried and inspected.

Coil stock is the source from which air fins and turbulator fins
are fabricated for this product. Cutting oil is the lubricant used
during fabrication, and afterward it is filtered (to remove metal
particles) before  reuse. Extruded aluminum tubes also require
oil to be sprayed on them when they are cut to  length and
deburred. Product headers and side sheets, also  made from
aluminum coil stock, generate metal scrap, require cutting oil
during formation, and ultimately  involve 1,1,1-trichloroethane
and perchloroethylene for degreasing. Spent solvent recovered
from a distillation unit is recycled  to the process, while still
bottoms are ultimately treated offsite after further distillation.
Tube assembly,  air fins,  headers,  and side sheets are pro-
cessed through a vacuum oven for brazing after manual as-

Air coolers are hand-assembled from  the clean components
before being  painted with a paint-solvent  mixture. The paint
booth generates  its own waste in the form of solvent and paint
from paint-gun cleaning,  water from the  paint booths' water
curtain, waste paint solids, and overspray. Product parts are

Round Tube Plate Fin Condensers  (RTPF)
Table t.  Summary of Current Waste Generation

Waste Generated                              Source of Waste
                                                   Annual Quantity
Annual Waste
   Costs ($)
Liquid Waste

     Machining Oils

     Still Bottoms
     Process Waste Water
Solid Waste
     Aluminum Scrap
Spent oil from machining operations.                        40 bbl

Still bottoms from perchloroethylene solvent                 25 bbl
recovery system.

Still bottoms from 1,1,1-trichloroethane solvent                11 bbl
recovery system.

Cleaning solution and rinse tank overflow from         1,057,000 gal
air cooler production.

Hot water flush from condenser production.             327,000 gal
Scrap from production of air coolers, air-                215,177 Ib
conditioner tubes, and round tube plate fin




    Steel Scrap

    Dried Epoxy Waste

    Paint Sludge
Scrap from round tube plate fin condensers.               40,200 Ib
Small amount from air cooler production                      4 gal
(to repair dents).

Spray painting of air coolers and immersion                  20 bbl
painting of condensers.


                                                                                           •U.S. Government Printing Office: 1992— 648-080/60016

Tab/a 2.   Summary of Recommended Waste Minimization Opportunities
         Present Practice
       Proposed Action
              Cost Savings
TVro vapor dogroasing units utilize on an
annual basis perchloroethylene (7795 gal)
and 1,1,1-trfchloroBthanB (3630 gal).
About 92-93% is lost by evaporation from
tfjs vapor-treating units. Also, solvent
recovery vis distillation generates still
bottoms consisting of 219 gal/yr of
pBrchloroothylonB and 528 gaVyr of 1,1,1-
trichloroethana which are sent offsite for

Charged air coolers are cleaned and
rinsed in a succession of three tanks,
each holding 1200 gallons. Overflow
(o wasta treatment occurs even
whon plant Is idled at a rate of
527,904 gaVyr/rinse tank.
Substitute soluble biodegradable
cteaners/degreasers to replace
chlorinated hydrocarbon solvents.
These materials are nonhazard-
ous and can be sewered directly.
Turn off water to the two rinse tanks
when not in use (approximately
15 hr/day) and convert to a
counter/lowing rinse system.
Estimated still bottom reduction = 747 gal/yr
Estimated still bottom disposal cost reduction
= $6,007/yr
Estimated raw material cost saving
= $62,640/yr'
Estimated implementation cost = $20,700
Simple payback = 0.3 yr
Estimated waste reduction = 657,844 gal/yr11
Estimated cost saving = $33,235/yr3
Estimated implementation cost = $3,480
Simple payback = 0.1 yr
Paint applied to two products (air
coolers and round tube plate fin
condensers) creates about 1100
galtyr of waste (water, paint solids,
usod plastic linings, and spray booth
Evaporative loss of perchhroethylene
and 1t1,1-trichloroethane occurs from
vapor dogreasing units.
Convert to electrostatic powder
coating to apply heat-fusible polymers
to metal substrates. Solvent and
other waste will be eliminated, and
overspray powder can be
collected and reused.
Fabricate and apply lightweight
plastic tops to cover tanks except
when parts are being removed from
or added to degreasing units to
reduce evaporative loss by 50%.
Estimated waste reduction = 1,100 gal/yr
Estimated waste disposal cost reduction
= $5,869/yr
Estimated net raw material cost saving
 = $22,885/yr
Estimated implementation cost = $100,640
Simple payback = 3.5 yr

Estimated solvent evaporation reduction
= 5,339 gal/yr
Estimated net raw material cost saving
= $26,375/yr'
Estimated implementation cost = $3,600
Simple payback = 0.1 yr
'  Porchhroothylene: $4.76/gal; 1,1,1-trichloroethane: $5.38/gal.
*  Gallons saved by turning off the water 15 hr/day, 5 day/wk, 47 wk/yr: 659,800
   Gallons saved by instituting a counterflowing rinse system:          197,964
                                                                 857,844 gal/yr
3  Water: $0.0012/gal in addition to 62% volume reduction in on-site waste water treatment system.
United States
Environmental Protection
         Center for Environmental
         Research Information
         Cincinnati, OH 45268
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