United States
Environmental Protection
Agency
National Risk Management
Research Laboratory
Research Triangle Park, NC 27711
Research and Development
EPA/600/SR-96/117
October 1996
4>EPA Project Summary
Pollution Prevention
Demonstration and Evaluation of
Paint Application Equipment and
Alternatives to Methylene
Chloride and Methyl Ethyl Ketone
J.M. Elion, J.B. Flanagan, J.H. Turner, J.T. Hanley, and E.A. Hill
The report gives results of demon-
strations of technologies to prevent or
control emissions of hazardous air pol-
lutants (HAPs) and volatile organic
compounds (VOCs) at the Marine Corps
Logistics Base in Albany, GA. The pro-
cesses with high solvent usage se-
lected for demonstration were: (1) paint
stripping using methylene chloride, (2)
cleaning paint equipment with methyl
ethyl ketone (MEK), and (3) applying
paint by spraying solventborne coat-
ings. For Demonstration (1) N-methyl
pyrrolidone (NMP) was chosen to re-
place methylene chloride because it ef-
fectively removed Chemical Agent Re-
sistant Coatings (CARCs) in laboratory
tests, is nonflammable, and is not clas-
sified as a HAP by EPA. The annual-
ized costs for NMP stripping are lower
than for methylene chloride stripping,
but implementation requires high capi-
tal investment. This substitution will
lower HAPS 11% from 1992 levels. For
Demonstration (2), a blend of 40% pro-
pylene carbonate and 60% benzyl alco-
hol (PC/BA), by weight, was chosen to
replace MEK. This choice was based
on the results of laboratory screening,
materials compatibility, and paint re-
moval efficiency tests. No capital in-
vestment was required. Based on the
demonstration, PC/BA cleans green
CARCs from the pumps as well as MEK,
and cleans epoxy primers better than
MEK. Advantages of using PC/BA are
lower vapor pressure, reduced solvent
use and labor time for cleaning, and
classification of the hazardous waste
as non-regulated by the Resource Con-
servation Recovery Act. The disadvan-
tage is a higher cost for the PC/BA blend
than for MEK. This substitution will lower
emissions from HAPs 21% from 1992
levels. The objective of Demonstration
(3) was to determine if the amount of
paint applied to a vehicle could be de-
creased by providing the painters with a
real-time readout of the amount of paint
they were using. A system was installed
that monitored paint use gravimetrically
by continuously measuring the weight
of the pot from which the paint was
pumped to the spray guns. The system
worked reliably, and paint use measure-
ments were obtained on 19 vehicles.
Results showed that, for identical ve-
hicles, differences up to 30% in the
amount of paint used occurred, indicat-
ing that potential exists for significant
reductions. No actual reductions were
shown during the demonstration.
This Project Summary was developed
by EPA's National Risk Management
Research Laboratory's Air Pollution
Prevention and Control Division, Re-
search Triangle Park, NC, 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).
Overview
The Clean Air Act Amendments of 1990
(CAAA) and Executive Order 12856 man-
date that military depot activities reduce
air emissions. Specifically, the CAAA re-
quires a reduction in hazardous air pollut-
ant (HAP) emissions for "major" sources
and Executive Order 12856 requires that
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military installations reduce HAP emissions
by 50% of their 1992 levels. Accordingly,
the U.S. EPA and the U.S. Marine Corps
Logistics Base (MCLB), Albany, GA, with
sponsorship from the Strategic Environ-
mental Research and Development Pro-
gram (SERDP), conducted an initial evalu-
ation and subsequent demonstration of
pollution prevention (P2) technologies for
reduction of HAPs. Processes and related
high solvent usage sources were identi-
fied and P2 recommendations were made.
EPA and the host facility MCLB performed
the research. Research Triangle Institute
personnel provided contractor support.
MCLB carries out maintenance activi-
ties on a wide variety of equipment from
small arms to tanks, trucks, and other
vehicles. Much of the maintenance on the
vehicles requires removing existing paint
prior to repairing procedures and applying
new paint once the maintenance has been
performed. The processes for paint strip-
ping, repainting, and cleaning of paint
equipment release significant amounts of
HAPs.
The purpose of this research was to
demonstrate viability of P2 technologies
on a full production scale at the MCLB.
Three processes with high solvent usage
were selected for demonstration:
• stripping paint by immersion in meth-
ylene chloride,
• cleaning paint equipment with methyl
ethyl ketone (MEK), and
• applying paint by spraying
solventborne coatings.
First Demonstration
For the first demonstration, n-methyl
pyrrolidone (NMP) was selected as the
alternative to methylene chloride for strip-
ping cured coatings from metal parts. NMP
was chosen during a scoping study for
the facility demonstration because it ef-
fectively removed Chemical Agent Resis-
tant Coatings (CARC) in laboratory tests,
is nonflammable, and is considered by
the EPA not to be a HAP. Two drawbacks
are that the NMP must be heated to be
effective, and NMP is subject to reporting
under the Superfund Amendments and
Reauthorization Act (SARA).
The first step in preparing for the dem-
onstration was to retrofit an existing tank
on the Base. The stripping tank required
plumbing to heat the bath with steam, and
a recirculating pump to provide enough
agitation to ensure uniform temperature
throughout the bath. An adjacent rinse
tank required a pump to draw recycled
NMP for rinsing stripped parts. Finally, a
vacuum distillation unit was installed to
reclaim used solvent from the stripping
bath and provide recycled NMP for rins-
ing. After the tank retrofit was completed,
the heating and recirculating systems were
tested using water. The stripping tank was
then emptied and filled with an initial
charge of 38 55-gal (208 L) barrels of
technical grade NMP. An additional ten
barrels was added to the stripping tank
later.
The NMP, when heated to 150 +10°F
(66 +6°C), was able to remove multiple
layers of CARC and strip parts to the
base metal within 3-4 hours. The heated
NMP was able to successfully remove
Plastisol®, a plastic coating, from battery
tie-down brackets. These parts were pre-
viously stripped in a hot alkaline bath,
followed by scraping and blasting to re-
move the coating. Also, NMP was able to
soften epoxy-based topcoats, but removal
usually required overnight soaking.
Second Demonstration
For the second demonstration, a blend
of propylene carbonate and benzyl alco-
hol was chosen to replace methyl ethyl
ketone (MEK) for cleaning the paint appli-
cation equipment (pumps, hoses, and
guns). This demonstration consisted of a
preliminary screening to identify several
possible solvent alternatives, testing to
select the most effective cleaners, and
full-scale demonstration at the MCLB.
Sixty-five alternative cleaners were
tested in preliminary screening for their
effect on fully cured single- and plural-
component CARCs and an epoxy primer.
From these 65 alternatives, 5 were se-
lected for further testing. The cleaners were
tested for their compatibility with materials
that would contact the paints and the
cleaner. No measurable weight gain or
loss, pitting, or other signs of corrosion
were found among any of the five clean-
ers or MEK and the four metals tested:
aluminum, stainless steel, nickel, and
brass. Material compatibility was also
tested with four plastics (Teflon®, acetal,
Nylon®, and Delrin®). Results showed
slight weight changes in all coupons tested
with the five cleaners and with MEK. Of
the five cleaners, the two showing the
least overall weight gain or loss for the
four plastics were evaluated for paint re-
moval efficiency in a laboratory setting.
Overall, both of the cleaners were compa-
rable to MEK for CARCs, and both clean-
ers were better than MEK at removing
white primer.
Based on the test results, the blend of
40% propylene carbonate and 60% ben-
zyl alcohol (PC/BA) by weight was se-
lected by the research team for demon-
stration. Subsequently, four barrels of this
cleaner were shipped to the base, and the
cleaner was used as a direct replacement
for MEK. No capital investment was re-
quired.
Use of the PC/BA cleaner was moni-
tored by weighing the amount of cleaner
flushed through the system. Amounts of
cleaner used for the initial prewash, the
final wash, and the filter wash were re-
corded. Date and time at start and finish
of each step were also recorded.
Results showed that PC/BA cleans
green CARC from the pumps as well as
MEK, and cleans epoxy primers from the
pumps better than MEK. Advantages of
using PC/BA are lowered inhalation haz-
ard to workers, and reduced cleaner us-
age and labor time for cleaning. Other
advantages are that PC/BA is non-regu-
lated by the source Conservation Recov-
ery Act, and the use of PC/BA signifi-
cantly decreases downtime of the primer
pumps. The disadvantage is a higher cost
for PC/BA than for MEK, but the higher
cost may be offset by cleaner recovery
and reclamation, and further waste reduc-
tion.
Third Demonstration
For the third demonstration, the objec-
tive was to determine if the amount of
paint required to coat a vehicle could be
reduced by providing the painters with a
real-time readout of how much paint they
were using. The study began with the
design, specification, purchase, and in-
stallation of a paint monitoring system in a
paint booth. The system monitored paint
use gravimetrically by continuously mea-
suring the weight of the 5-gal (18.9 L) pot
that held the paint to be pumped to the
spray guns. The system included program-
mable digital scales, a small printer, and
large remote displays visible from within
the paint booth. Displays continuously
showed the cumulative amount of paint
used.
The initial portion of the test period was
devoted to baseline or control measure-
ments taken "without feedback" of paint
consumption. During this period, the dis-
plays were not visible to the painters. Af-
ter sufficient baseline information had been
gathered, the displays were installed in
the paint booth and the painters were
instructed in how the displays could be
used to control their usage rate. "Target"
levels for High Mobility Multipurpose
Wheeled Vehicles (HMMWVs) and 5-ton
(4.5-tonne) trucks were set based on the
lowest usage during the baseline period.
The system proved to work reliably, and
paint usage measurements were obtained
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on nineteen vehicles: 10 HMMWVs, five
5-ton cargo trucks, and four other vehicles.
Measurements show that, for one set of
identical vehicles (the 10 HMMWVs), paint
consumption differed by up to 30% be-
tween the highest and lowest vehicles.
This indicates that a potential for signifi-
cant reductions may exist. However, dur-
ing the brief study period, no statistically
significant decrease in paint usage was
seen between the baseline (without feed-
back) and the experimental (with feed-
back) portions of the demonstration. This
may be due to the brevity of the demon-
stration and to the presence of monitoring
personnel at the paint booth during the
baseline period. However, the system
could still provide reductions in paint us-
age and other benefits when used in com-
bination with other strategies such as mix-
ing only the amount needed for each ve-
hicle rather than the current practice of
mixing paint in multiples of 5 gal. The
system could also be used in training new
employees, and in assessing the impact
of equipment inspection and maintenance
practices on paint consumption.
It is recommended that MCLB continue
to collect paint usage data for several
months to determine if measurable reduc-
tions in paint usage are realized after the
staff becomes accustomed to the equip-
ment.
The MCLB has already replaced 1,1,1-
trichloroethane vapor degreasers with
aqueous parts washers. This change alone
will reduce emissions from HAPs by 16%.
By eliminating the methylene chloride for
immersion stripping, the MCLB can re-
duce emissions another 11%. By replac-
ing MEK with a PC/BA blend for cleaning
paint application equipment, the MCLB can
reduce emissions from HAPs an additional
21%. These three changes combined re-
sult in a reduction of emissions of 48%.
The MCLB plans to replace solventborne
CARCs with waterborne CARCs in 1996
to achieve over 50% reduction in emis-
sions from HAPs.
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J.M. Elion, J.B. Flanagan, J.H. Turner, J.T. Hartley, and E.A. Hill are with Research
Triangle Institute, Research Triangle Park, NC 27709.
J.K. Whitfield is the EPA Project Officer (see below).
The complete report, entitled "Pollution Prevention Demonstration and Evaluation
of Paint Application Equipment and Alternatives to Methylene Chloride and
Methyl Ethyl Ketone, "(Order No. PB97-104632; Cost: $49.00, subjectto 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:
Air Pollution Prevention and Control Division
National Risk Management Research Laboratory
U. S. Environmental Protection Agency
Cincinnati, OH 45268
United States
Environmental Protection Agency
Center for Environmental Research Information (G-72)
Cincinnati, OH 45268
Official Business
Penalty for Private Use $300
BULK RATE
POSTAGE & FEES PAID
EPA
PERMIT No. G-35
EPA/600/SR-96/117
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