United States
Environmental Protection
Agency
Research and Development
Air and Energy Engineering
Research Laboratory
Research Triangle Park, NC 27711
EPA/600/S2-90/051 Feb. 1992
Project Summary
VOC Emission Reduction
Study at the Hill Air Force Base
Building 515 Painting Facility
Jacqueline Ayer and Carolyn Hyde
The objective of this project was to
develop practical technologies for eco-
nomically reducing volatile organic com-
pound (VOC) emissions from typical Air
Force painting operations. The painting
facility selected for study is located in
Building 515 at Hill Air Force Base, Utah.
Practical and economical emission con-
trol technologies that may be used at
this and other Air Force facilities were
developed based on the results of in-
booth and exhaust duct sampling for
paniculate and hazardous constituent
concentrations.
This Project Summary was developed
by EPA's Air and Energy Engineering
Research Laboratory, Research Triangle
Park, NC, to announce key findings of
the research project that is fully docu-
mented in a separate report of the same
title (see Project Report ordering infor-
mation at back.
Introduction
Underthe Clean Air Act and various state
and local laws, organic solvents and coat-
ing compounds used in routine Air Force
maintenance operations are subjectto VOC
emission regulations. Air Force installations
are experiencing increased pressure from
regulatory agencies to reduce organic com-
pound emissions from painting and coating
operations. The capital and operating costs
associated with controlling emissions from
such operations are a function of the flow
rate of the exhaust gas passing through the
control device. The goal of this program was
to develop safe and cost-effective VOC
emission control strategies.
To characterize the emission rate and
distribution of hazardous compounds in the
paint booth during painting operations, si-
multaneous air samples were taken in the
exhaust duct and at 22 positions inside the
booth. VOC, particulate, and isocyanate air
samples were taken during normal opera-
tion of the painting facility. A solvent mass
balance was performed in which VOC emis-
sion rates were compared to paint usage
and analysis data to confirm measurement
accuracy.
Methodology
Personal sampling pumps were sus-
pended at 22 sampling positions in the paint
booth during painting. To determine in-booth
particulate concentrations, sample air was
drawn through cellulose ester filters con-
nected to the suspended sampling pumps,
in accordance with National Institute of
Occupational Safety and Health (NIOSH)
Method 500. The filters were weighed sev-
eral times before and after sampling to
determine the quantity of particulate col-
lected from the known sample volume. To
determine particulate emission rates from
the booth, isokinetic particulate samples
were drawn from the exhaust duct accord-
ing to Environmental Protection Agency
(EPA) Method 5. For comparison, particu-
late samples were drawn from the duct
using NIOSH Method 500.
Integrated VOC concentration measure-
ments were taken in the booth and exhaust
duct by drawing sample air through NIOSH
charcoal tubes, in general accordance with
NIOSH Method 1300. Organic constituents
were adsorbed onto the charcoal, which
was subsequently extracted with a solvent
formulation developed for this test series.
The extract was analyzed with a gas chro-
matograph/flame ionization detector (GC/
FID). Continuous (real-time) organic sam-
pling was performed in the exhaust duct to
Printed on Recycled Paper
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determine VOC emission rates. Two con-
tinuous organic sampling methods were
used for this test series: Bay Area Air Qual-
ity ManagementDistrfct (BAAQMD) Method
ST-7 and EPA Method M25A. Method ST-
7spocifiesthat sample airbe drawn through
a catalytic furnace, in which the organic
const'rtuentsareoxidizedtoCO2.Thesample
stream is then passed through a
nondispersive infrared detector (NDIR),
which monitors the CO concentration.
Method 25 Aspec'rfies thattne sample stream
be passedthrough an FID, which measures
organic concentrations directly.
Isocyanate concentrations in the booth
and exhaust duct were measured accord-
ing to Occupational Safety and Health Ad-
ministration (OSHA) Method 42, which speci-
f iasthatsample airbe passedthrough chemi-
cally treated glass fiber filters. Isocyanates
are collected on the filters, which are subse-
quently analyzed using high performance
liquid chromatography (HPLC).
Airflow rates were measured in the booth
using a calibrated hotwire anemometer and
intheexhaust'ductaccordingtoEPAMethod
2 procedures. In addition, paint usage rates
were determined by posting a crew member
in the booth to monitor paint start and stop
times and by weighing the paint-dispensing
container before and afterthe painting cycle.
Volatile and semivolatile organic com-
pound concentrations were measured in
the water curtain sump water according to
EPA Methods 8240 and 8270, respectively.
Thetota! organic carbon (TOG) and residue
concentrations were monitored twice daily
by collecting water samples and analyzing
them according to EPA Methods 9060 and
160.3, respectively.
Test Description
Operating parameters (i.e., flow rates and
paint usage rates) were evaluated before
and after each painting cycle; sampling was
performed during painting. Each day, a dif-
ferent sampling protocol was used (i.e.,
VOC, particulate, and isocyanate sampling
were performed on different days). Because
there were two painting cycles per day,
each sampling effort was performed in du-
plicate.
Results
Except for areas directly in the path of the
paint spray gun, the highest concentrations
of hazardous constituent compounds were
found in the lower strata of the booth, at 4 ft
(1.2 m) in height. Above 8 ft (2.4 m),
nondetectable levels of hazardous com-
pounds were found. Some of the highest
VOC concentrations measured were near
the painter. Metals, particulate, and isocya-
nate concentrations were also somewhat
high in the vicinity of the painter; however,
the highest concentrations were measured
at ground level near the booth exhaust face.
Occasionally, high concentrations of haz-
ardous compounds were measured in sin-
gular isolated areas. It is suspected that
these high concentrations resulted from the
painter's inadvertently applying paint directly
to the sample surface.
Conclusions
The concentration profiles obtained for
the hazardous compounds present in the
booth indicate that significant stratification
occurs during painting. A system for de-
creasing the flow to a downstream VOC
emission control device can be designed
that takes advantage of this concentration
stratification. Decreasing the flow rate to a
VOC emission control device lowers asso-
ciated control costs. The flow-reduction sys-
tem proposed on the basis of thetest results
employs a split-flow exhaust process in
which the exhaust stream from the lower
zone of the booth (containing the highest
concentrations) is vented to a VOC emis-
sion control device. The exhaust stream
from the upper zone of the booth is vented
to the outdoors. A system such as this can
lower the flow rate to an emission control
device by 50% or more and, at the same
time, decrease VOC emissions by 70% or
more.
Additional conclusions are that hazard-
ous compound concentrations in the vicinity
of the painter are higher than in other re-
gions of the booth and that concentrations
of hazardous compounds measured in the
exhaust duct are far below the permissible
exposure limits (PELs) specified by OSHA.
These results indicate that a recirculation
system, in which a large portion of the
exhaust air is recirculated back into the
booth, can be safely adopted as an alterna-
tive means of decreasing the exhaust flow
rate. In this system, the P9rtion not
recirculated is ventedto an emission control
device.
Recommendations
Emissions may be reduced by a number
of system and process alterations. Some
emissions can be reduced by replacing the
two-part green primer currently used by the
facility tested with a three-part, water-re-
ducible primer that is in common use at
other Air Force painting facilities.
Cost-effective VOC emission control can
be realized by reducing the flow rate to an
emission control device. This may be done
by either employing a split-flow ventilation
system as described above or installing an
exhaust air recirculation system. A third
option combining these ventilation system
modifications is perhaps the most environ-
mentally sound and economical option.
&U.S. GOVERNMENT PRINTING OFFICE: 1992 - 648-080/40176
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Jacqueline Ayer and Carolyn Hyde are withAcurex Corp., Mountain View, CA 94039.
Charles H. Darvln is the EPA Project Officer (see below).
The complete report, entitled "VOC Emission Reduction Study at the Hill Air Force
Base Building 515 Painting Facility," (Order No. ADA 198-092; Cost: $26.00, 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 Off her can be contacted at:
Air and Energy Engineering Research Laboratory
U.S. Environmental Protection Agency
Research Triangle Park, NC 27711
United States
Environmental Protection
Agency
Center for Environmental
Research Information
Cincinnati, OH 45268
BULK RATE
POSTAGE & FEES PAID
EPA
PERMIT No. G-35
Official Business
Penalty for Private Use $300
EPA/600/S2-90/051
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