DRAFT
AUTOMOBILE REFINISHING
CONTROL TECHNIQUES GUIDELINE
U. S. Environmental Protection Agency
Chemicals and Petroleum Branch
Research Triangle Park, North Carolina 27711
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TABLE OF CONTENTS
Chapter Page
1.0 INTRODUCTION 1-1
2.0 PROCESS DESCRIPTION AND MODEL SHOPS 2-1
2.1 INDUSTRY OVERVIEW 2-1
2.2 PROCESS STEPS AND MATERIALS 2-2
2.2.1 Surface Preparation 2-3
2.2.2 Pretreatment Wash Primer and Precoat
Application 2-3
2.2.3 Primer Surface Application 2-4
2.2.4 Primer Sealer Application 2-4
2.2.5 Topcoat Application 2-4
2.3 COATING TYPES 2-6
2.3.1 Lacquer Coatings 2-7
2.3.2 Enamel Coatings 2-7
2.3.3 Urethane Coatings 2-8
2.3.4 Waterborne Coatings 2-8
2.3.5 Additives and Specialty Coatings . . . 2-8
2.4 SPRAY BOOTHS 2-9
2.5 SPRAY EQUIPMENT 2-11
2.5.1 Conventional Airless Spray Guns .... 2-12
2.5.2 High-Volume, Low-Pressure Spray Guns . 2-13
2.5.3 Electrostatic Spray Guns 2-15
2.6 EQUIPMENT CLEANING . . 2-15
2.7 SPECIAL CONSIDERATIONS 2-19
2.8 MODEL SHOPS 2-2 0
2.8.1 Model Shop Characteristics 2-2 0
2.8.2 Model Shop Equipment 2-21
2.8.3 Coating Usage in the Model Shops ... 2-23
2.9 REFERENCES 2-26
3.0 EMISSION CONTROL TECHNIQUES 3-1
3.1 INTRODUCTION 3-1
3.2 EMISSION REDUCTIONS FROM SURFACE PREPARATION . . 3-2
3.3 EMISSION REDUCTIONS FROM COATING APPLICATIONS . . 3-2
3.3.1 Lower VOC Coatings 3-3
3.3.2 High-Transfer-Efficiency Spray
Equipment 3-9
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TABLE OF CONTENTS (continued)
3.3.3 New Developments in Spray Equipment . . 3-9
3.4 EMISSION REDUCTIONS FROM GUN CLEANING 3-9
3.5 ADD-ON CONTROLS 3-10
3.5.1 Incineration 3-10
3.5.2 Carbon Adsorption 3-14
3.5.3 Biof iltration 3-15
3.6 EMISSION REDUCTIONS FROM IMPROVED
HOUSEKEEPING PRACTICES AND TRAINING
PROGRAMS 3-15
3.7 SUMMARY OF EMISSION CONTROL TECHNIQUES 3-16
3.8 REFERENCES 3-18
4.0 EMISSION ESTIMATION TECHNIQUES 4-1
4.1 SURFACE PREPARATION 4-1
4.1.1 Baseline Volatile Organic Compound
Emissions from Surface Preparation . . 4-1
4.1.2 Reduction of VOC from Surface
Preparation Operation 4-3
4.2 COATING APPLICATIONS 4-3
4.2.1 Baseline VOC Emissions from Coating
Applications 4-3
4.2.2 Reduction of Volatile Organic
Compound Emissions from Coating
Applications 4-8
4.3 GUN CLEANING 4-9
4.3.1 Baseline Volatile Organic Compound
Emissions from Gun Cleaning 4-9
4.3.2 Reduction of Volatile Organic
Compound Emissions Due to Use of a
Gun Cleaner 4-15
4.4 REDUCTION OF VOLATILE ORGANIC COMPOUND
EMISSIONS WITH ADD-ON CONTROLS 4-17
4.5 REDUCTION OF VOLATILE ORGANIC COMPOUND
EMISSIONS WITH IMPROVED HOUSEKEEPING
PRACTICES 4-18
4.6 SUMMARY OF EMISSION ESTIMATION TECHNIQUES .... 4-20
4.7 REFERENCES 4-22
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TABLE OF CONTENTS (continued)
4.7 REFERENCES 4-22
5.0 IMPACT ANALYSIS OF ALTERNATIVE CONTROL
TECHNIQUES 5-1
5.1 COSTS OF CONTROLLING EMISSIONS FROM SURFACE
PREPARATION 5-1
5.2 COSTS OF CONTROLLING EMISSIONS FROM COATING
APPLICATIONS 5-2
5.2.1 Coating Costs 5-2
5.2.2 Spray Booth Costs 5-4
5.2.3 Total Coating Costs 5-6
5.3 COSTS OF CONTROLLING EMISSIONS FROM
GUN CLEANING 5-9
5.4 COSTS OF CONTROLLING EMISSIONS WITH
ADD-ON CONTROLS 5-9
5.4.1 Catalytic Incineration Costs 5-9
5.4.2 Carbon Adsorption Costs 5-11
5.5 ENVIRONMENTAL IMPACTS OF CONTROLLING
VOLATILE ORGANIC COMPOUND EMISSIONS 5-13
5.5.1 Air Quality Impacts 5-13
5.5.2 Water Quality Impacts 5-13
5.5.3 Hazardous Waste Impacts 5-14
5.5.4 Solid Waste Impacts 5-14
5.5.5 Energy Impacts 5-14
5.6 SUMMARY OF IMPACTS OF ALTERNATIVE CONTROL
TECHNOLOGIES 5-14
[SUMMARY OF REASONABLY AVAILABLE CONTROL TECHNOLOGY
(to be completed at a later date)]
5.7 REFERENCES 5-19
6.0 FACTORS TO CONSIDER WHEN IMPLEMENTING REASONABLY
AVAILABLE CONTROL TECHNOLOGY 6-1
6.1 INTRODUCTION 6-1
6.2 DEFINITIONS 6-1
6.3 APPLICABILITY 6-4
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TABLE OF CONTENTS (continued)
6.4 FORMAT OF STANDARDS 6-5
6.4.1 Operational (Process and Material
Change) Standard 6-5
6.4.2 Equipment Standard 6-6
6.4.3 Add-on Control Devices 6-6
6.5 OPERATIONAL STANDARDS 6-7
6.5.1 Surface Preparation Products 6-7
6.5.2 Primer Category 6-7
6.5.3 Topcoats 6-8
6.5.4 Additives and Specialty Coatings . . . 6-8
6.5.5 Improved Housekeeping Practices .... 6-9
6.6 EQUIPMENT STANDARDS 6-9
6.6.1 Spray Equipment 6-9
6.6.2 Gun Cleaners 6-10
6.7 ADD-ON CONTROL DEVICES 6-10
6.8 REPORTING AND RECORDKEEPING 6-10
6.8.1 Operational Standards 6-11
6.8.2 Equipment Standards 6-11
6.8.3 Add-on Control Devices 6-12
6.9 REFERENCES 6-13
APPENDIX A CONTACTS A-l
APPENDIX B EMISSION ESTIMATION B-l
APPENDIX C COST CALCULATIONS C-l
APPENDIX D CTG MODEL RULE FOR AUTOMOBILE REFINISHING . D-l
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Table
LIST OF TABLES
Page
2-1 Model Shop Characteristics 2-22
2-2 Coating Use by Model Shop 2-24
3-1 VOC Content of Baseline Option 1 and
Option 2 Coatings 3-6
4-1 Surface Preparation Emissions and Emission
Reductions 4-4
4-2 Baseline Model Shop Coating Emissions 4-6
4-3 Option 1 and 2 Coating Characteristics 4-10
4-4 VOC Emission Reductions from Coatings (Option 1) . . . 4-11
4-5 VOC Emission Reductions from Coatings (Option 2) . . . 4-12
4-6 Total VOC Emission Reductions With Lower
VOC Coatings 4-13
4-7 Gun Cleaning Emissions and Emission Reductions .... 4-16
4-8 Add-On Control Emission Reductions for Model
Shop H 4-19
5-1 Surface Preparation Costs 5-3
5-2 Coating Costs 5-5
5-3 Spray Booth and Coating Costs 5-7
5-4 Gun Cleaner Costs 5-10
5-5 Add-on Control Costs for Model Shop H 5-12
5-6 Energy Impacts of Spray Booth Use 5-15
5-7 Energy Impacts of Catalytic Incineration
and Carbon Adsorption for Model Shop H 5-16
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LIST OF FIGURES
Figure Page
2-1 Spray Booth Make-up and Exhaust Air Orientation ... 2-10
2-2 Conventional Spray Equipment 2-14
2-3 Typical Enclosed Gun Cleaner 2-16
2-4 Typical Open Gun Cleaner 2-18
3-1 Direct Thermal Incinerator 3-12
3-2 Catalytic Incinerator 3-13
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1.0 INTRODUCTION
The 1990 Clean Air Act (CAA) Amendments require that State
Implementation Plans (SIPs) for certain ozone nonattainment areas
be revised to require the implementation of reasonably available
control technology (RACT) to control volatile organic compound
(VOC) emissions from sources for which the U. S. Environmental
Protection Agency (EPA) has already published a Control
Techniques Guideline (CTG) or for which EPA will publish a CTG
between the date of enactment of the 1990 CAA Amendments and the
date an area achieves attainment status. Section 172(c)(1)
requires nonattainment area SIPs to provide, at a minimum, for
"such reductions in emissions from existing sources in the area
as may be obtained through the adoption, at a minimum, of
reasonably available control technology..."
As a starting point for ensuring that these SIPs provide for
the required emission reduction, EPA, in the Federal Register
notice 44 FR 53761 (September 17, 1979), defines RACT as: "the
lowest emission limitation that a particular source is capable of
meeting by the application of control technology that is
reasonably available considering technological and economic
feasibility." The EPA has elaborated in subsequent Federal
Register notices on how States and EPA should apply the RACT
requirements (See 51 FR 43814, December 4, 1989; and 53 FR 45103,
November 8, 1988).
The CTG1s are intended to provide State and local air
pollution authorities with an information base for proceeding
with their own analyses of RACT to meet statutory requirements.
The CTG's review current knowledge and data concerning the
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technology and costs of various emission control techniques.
Each CTG contains a "presumptive norm" for RACT for a specific
source category, based on EPA's evaluation of the capabilities
and problems general to that category. Where applicable, EPA
recommends that States adopt requirements consistent with the
presumptive norm. However, the presumptive norm is only a
recommendation; states may develop their own RACT requirements on
a case-by-case basis, considering the economic and technical
circumstances of individual sources. It should be noted that no
laws or regulations preclude States from requiring more control
than recommended as the presumptive norm for RACT. A particular
State, for example, may need a more stringent level of control in
order to meet the national ambient air quality standard (NAAQS)
for ozone.
This CTG is one of at least 11 CTG's that EPA is required to
publish within 3 years of enactment of the 1990 CAA Amendments.
It identifies RACT for control of VOC emissions from automobile
refinishing, including surface preparation, coating applications,
and paint spray gun cleaning operations. This document is
currently in draft form and is being distributed for public
comment. Public comments will be reviewed and incorporated as
appropriate before EPA finalizes the CTG.
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2.0 PROCESS DESCRIPTION AND MODEL SHOPS
This chapter presents a profile of the automobile
refinishing industry, describes the process steps involved in
refinishing, and presents the model shops used to estimate the
national impacts of a Control Techniques Guideline (CTG) on the
automobile refinishing industry. Section 2.1 provides an
overview of the automobile refinishing industry. Section 2.2
describes the process steps and materials involved in refinishing
an automobile. Section 2.3 discusses the types of coatings used
in refinishing. Spray booths are discussed in Section 2.4, and
spray equipment is discussed in Section 2.5. Section 2.6
discusses equipment cleanup. The "systems approach" and other
special considerations are discussed in Section 2.7. The model
shops are presented in Section 2.8.
2.1 INDUSTRY OVERVIEW
The automobile refinishing industry is composed of body
shops that repair and refinish the interior and exterior bodies
of automobiles, vans, motorcycles, and light- and medium-duty
truck cabs and chassis. The refinishing industry deals primarily
with aftermarket vehicles [vehicles after they have been
purchased from an original equipment manufacturer (OEM) but
includes dock repair of imported vehicles and dealer repair of
transit damage before the sale. Other types of mobile equipment,
such a$ farm machinery and construction equipment, are not covered
by this document. The refinishing of these vehicles is covered
in another CTG document.1
The refinishing industry reportedly consists of at least
63,000 individual facilities of varying sizes and technology
levels. The industry is characterized by essentially four types
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of shops: small- and medium-size body shops, new car dealerships,
and large production shops. The work performed by most small-
and medium-size body shops tends to be somewhat confined to
repairing and refinishing a small portion of the vehicle (e.g., a
panel, or a "spot" on a panel). Sixty percent of car dealerships
(approximately 13,500 facilities nationwide) reportedly operate
body shops.2 New car dealers perform refinishing services not
only on new cars damaged in shipment, but also on automobiles
which are brought in by customers for repair. Other types of
shops specialize in repainting the entire vehicle. These shops
are often known in the industry as production shops.
In contrast, the refinishing industry in many European
countries is reportedly structured differently. There are fewer
shops, and shops are said to have the most up-to-date equipment
and work practices. All shops are reportedly licensed, and shop
workers must go through apprenticeship programs.
The refinishing industry in the U.S. is a dynamic industry
that has changed dramatically in the past decade.3 The industry
is shifting away from a large number of facilities toward fewer,
larger shops, primarily because of forces such as worker health
and safety issues and hazardous waste management concerns.2 It
is estimated that there were approximately 125,000 shops in
operation in 1976, but by 1993, there may be only 50,000 shops in
operation.3
2.2 PROCESS STEPS AND MATERIALS
The procedures used for refinishing automobiles vary from
shop to shop. In general, some basic steps are followed when
refinishing a vehicle, whether the job is to repair a spot,
panel, or to paint an entire vehicle. The surface of the vehicle
is first thoroughly cleaned to ensure proper adhesion of the
coating, the metal surface is primed, a topcoat is applied, and
the spray equipment is cleaned. The following sections describe
the surface preparation and coating application processes (for
primers and topcoats), each of which has traditionally been a
source of volatile organic compound (VOC) emissions due to the
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presence of VOC's in the products. Primers used in automobile
refinishing include pretreatment wash primers, precoats, primer
surfacers, and primer sealers. Topcoats can be single-stage,
two-stage, or three-stage. The spray equipment cleaning process,
also a source of VOC emissions, is discussed in Section 2.5.
2.2.1 Surface Preparation
The first step in the automobile refinishing process is the
preparation of the surface to be refinished. The surface is
normally washed with detergent and water to remove dirt and
water-soluble contaminants and is allowed to dry. It is then
cleaned with either solvent or a solvent-based surface
preparation product to remove wax, grease, and other
contaminants. Surface preparation products generally consist of
solvent and surfactant components, and the products are wiped off
after they have effectively removed the wax and grease from the
surface to be refinished. This step is important to ensure
proper adhesion of the coatings, and is necessary even if the old
surface does not have to be removed or if new parts are to be
coated.
If the existing primer/topcoat is in good condition (no
chips or cracks), it should be a sufficient base for refinishing
after it is scuff sanded. The existing finish is removed (down
to bare metal) if it has imperfections and for accident repairs
(if the damaged panel is not replaced).
Removal of the old surface coating is generally achieved by
one of three methods: sanding, chemical removal (most efficient
for large areas and complete panels), or sand blasting (best for
complete vehicles or extremely large areas).4 This surface
removal step is then followed by a final solvent wipe.
2.2.2 Pretreatment Wash Primer and Prfecoat Application
If bare metal is to be coated, the next step in the
automobile refinishing process is the application of a
pretreatment wash primer or a precoat. These products are
applied to provide corrosion resistance and promote adhesion.5
Pretreatment wash primers are applied prior to application of
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solvent-borne primers, and are coatings that contain at least
0.5 percent acid by weight and provide surface etching. Precoats
are applied prior to application of waterborne primers primarily
to deactivate the metal surface to prevent corrosion.2
2.2.3 Primer Surfacer Application
A primer surfacer is the next coating applied, but is often
used only if surface imperfections need to be filled. A primer
surfacer builds film in order to permit sanding. Adhesion and
corrosion resistance are additional benefits of primer surfacers.
2.2.4 Primer Sealer Application
If there are no surface imperfections to be repaired, some
shops choose to use only a primer sealer. A primer sealer is
applied prior to topcoat application to provide more corrosion
resistance, promote adhesion of subsequent coatings, and enhance
the uniformity of the topcoat appearance.
2.2.5 Topcoat Application
The topcoat, which is generally a series of coats, is
applied over the primer coats and determines the final color of
the refinished area. Since most repairs are spot and panel
repairs, the automobile refinisher is concerned with matching the
OEM color as closely as possible. This matching is accomplished
by blending the repair into the surrounding area. The first coat
is applied to the immediate area being repaired, with subsequent
coats extending beyond this area. In some cases, an extreme
amount of reducing thinner (VOC) is added to the coating to
further improve the colormatch. Because the solids in this
"blend coatN are more dilute, a portion of the original color
shows through and effects a gradual transition to mask any color
differences between the refinished area and the original color.
An alternative to the use of this blend coat would be to fade the
edge of the refinished area into the original color by varying
the air pressure of the spray gun or the distance of the gun from
the car surface.
Metallic or iridescent finishes differ from solid color
finishes because they contain small metal flakes, typically
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aluminum, that are suspended in a mixture of binders, solvent,
and pigment. Light reflects off of these metal flakes to produce
the metallic effect. The rate of solvent evaporation following
application of a metallic topcoat determines the alignment and
depth of the metallic flakes. If evaporation occurs too quickly,
the flakes will be frozen in random patterns near the film
surface, giving the finish a light silvery appearance.
Conversely, if evaporation occurs too slowly, the flakes will
sink deeper into the wet paint, resulting in a reduced
reflectivity and a darker finish. These finishes are among the
more difficult to color match successfully.
Topcoats may be applied in single-stage, two-stage, or
three-stage coating systems. Each stage of a two- or three-stage
topcoat directly impacts the other stages and the final color
match capability and durability of the entire topcoat system.
Two-stage basecoat/clearcoat systems may have either a solid
or a metallic basecoat, followed by a transparent clearcoat for
protection and gloss. These systems are popular because of their
deep, rich finish, which reportedly cannot be duplicated by a
single-stage coating. In a two-stage topcoat refinish system,
the basecoat is typically one-third of the film build or volume
solids used, and the clearcoat is two-thirds of the film build or
volume solids used.8
Three-stage systems have also been developed and include a
basecoat, midcoat, and clearcoat. Three-stage refinish systems
are often used to match three-stage OEM finishes. In a
three-stage topcoat refinish system, the basecoat and midcoat
account for one-half of the film build and the clearcoat for
one-half.
As OEM topcoats have become more complex, the precise
matching of original colors by refinishers has become more
difficult, and, in many cases, increased solvent usage has
resulted from an effort to achieve blending. For example, the
OEM's use metallic and "pearl" coatings on at least 50 percent of
all new vehicles.5 As discussed above, colormatching these
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coatings is difficult and is dependent upon the alignment of the
metallic particles, which is influenced by the evaporation rate
of the solvent.
Besides dealing with colormatching complex finishes such as
metallics, annual changes in OEM color selections add a dimension
of difficulty to achieving colormatch. One automobile
manufacturer typically will introduce over 10 new colors in a
single year.7 New car colors are developed by coating
manufacturers who preview these colors with automobile
manufacturing stylists. The automobile manufacturer then
determines from market research which colors to use. Once a new
color has been selected, the coating manufacturers develop the
coatings that achieve the desired appearance and performance
specifications. Trial application by the automobile manufacturer
may then take a number of months before the coating is approved
for line application.7 The typical automobile refinisher
however, lacks this period of "trial application,w and is
expected to meet color specifications and customer satisfaction
for every job, regardless of previous experience with a
particular color. Although refinish coating formulations are
developed for each OEM color, there is often variability in the
shad@(^EK$> color, requiring the refinisher to make adjustments to
the formula. Due to the difficulty of matching certain colors,
the refinisher must sometimes refinish more of the vehicle,
rather than just the damaged portion, thereby increasing coating
usage. The automobile refinisher's ability to achieve colormatch
is thus highly influenced by OEM's decisions to introduce
additional colors.
2.3 COATING TYPES
There is a difference between the coatings applied by the
OEM's and those applied by refinishing shops. At OEM facilities,
coatings can be baked with temperatures up to 400°F (204°C) to
cure them, because no temperature sensitive materials have yet
been installed. Automobile refinishing shops, on the other hand,
cannot use such high temperatures because the vehicle's
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upholstery, glass, wiring, and plastic fittings would be damaged.
The coatings used by refinishing shops must dry at low
temperatures (less than 150°F) .
Primers and topcoats, whether solid colors or metallics, can
be classified into lacquer, enamel, and urethane coatings. The
major difference between these types of coatings is the chemistry
that occurs during the drying or curing stage. Lacquer coatings
cure by solvent evaporation only, while enamel and urethane
coatings cure by evaporation and chemical cross-linking
reactions.4 In addition, urethane coatings typically have a much
higher percent of solids by weight than either enamels or
lacquers. This is important because the solids contained in a
coating are the components that create film build on a surface.
The higher the solids content of a coating, the lower the volume
of coating that must be used to obtain a film of the desired
thickness. Lacquer coatings have a higher amount of solvents as
sprayed, per gallon of solids, than enamel or urethane coatings.8
Besides increasing the solids content of a coating,
replacing the solvent with water is another way to reduce VOC
emissions from coatings.
2.3.1 Lacquer Coatings
Lacquers were one of the first types of coatings used on
automobiles. Lacquers dry more quickly than enamels or urethanes
and, once dry, can be buffed to remove surface imperfections.
These characteristics allow body shops that are not equipped with
spray booths and drying ovens to achieve high quality, dirt-free
finishes that might not be possible with slower-drying,
higher-solids enamel or urethane coatings. In addition, the
amount of drying time between coating applications can be
reduced. One disadvantage of lacquers is that time and labor
must be expended in buffing (compounding) lacquer finishes to
achieve full luster.4
2.3.2 Enamel Coatings
Enamel coatings, either alkyd or acrylic, are used
frequently in the automobile refinishing industry. Alkyd enamel
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is the chemical combination of an alcohol, an acid, and an oil.
Developed in 1929, alkyd enamel is less expensive than acrylic
enamel but has inferior durability. Acrylic enamels are
characterized by excellent durability. Both types of enamels
have a natural high gloss and do not require compounding to
. coatings can be
have hardeners added to promote curing.
2.3.3 Urethane Coatings
Urethane coatings are a more recently developed coating type
typically formed by a reaction between a hydroxyl-containing
material and a polyisocyanate hardener. Their use is growing
because of their superior gloss retention and durability. They
are frequently used for overall refinishing jobs, such as
refinishing fleet vehicles, and are used by the more technically
sophisticated refinishing shops. Urethane coatings dry more
slowly than lacquers and enamels, and spray booths may be
necessary in order to provide clean, dust-free curing
environments. The presence of trace amounts of residual
isocyanates requires the use of an air-supplied respirator to
reduce worker exposure. Isocyanate-free hardeners are available.
2.3.4 Waterborne Coatings
A coating is considered waterborne if it contains more than
5 percent water in its volatile fraction.9 Like enamel and
urethane coatings, waterborne coatings dry slowly. The use of a
spray booth may be necessary to prevent contamination and
facilitate drying. Waterborne primers and basecoats are
currently available,
2.3.5 Additives and Specialty Coatings
Some additives and specialty coatings are necessary for
unusual performance requirements, and are used in relatively
small amounts to impart or improve desirable properties.
Problems such as "fish eye" defects (a surface imperfection that
can occur when the old finish contains silicone, for example) can
be prevented by the use of additives. Other additives and
These acrylic resins
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specialty coatings include uniform finish blenders, elastomeric
materials for flexible plastic parts, gloss flatteners, and
anti-glare/safety coatings.
2.4 SPRAY BOOTHS
Spray booths provide clean, well-lit, and well-ventilated
enclosures for coating operations. Because of their longer
drying times, enamel, water-based, and urethane coatings are best
applied in a spray booth to minimize the possibility of dirt
adhering to the damp coating. Spray booth ventilation increases
the air exchange rate and provides clean (dirt-free) air to the
booth. This increased air flow hastens drying, and provides a
safer work environment for the refinisher by removing solvent
vapors from the booth. Booth ventilation also removes the
coating overspray, the portion of the coating solids that does
not adhere to the surface being sprayed.
There are three types of spray booths used in the
refinishing industry: crossdraft, downdraft, and semi-
downdraft10 (Figure 2-1). Traditionally, the air flow in spray
booths has been from one side of the booth to the other, or
crossdraft. In the crossdraft design, incoming air is pulled
into the booth through filters located in the entrance door. The
air then travels along the length of the car, passes through
coating arrestor filters at the opposite end, which remove
coating overspray, and finally exhausts VOC's through an exhaust
stack.
Downdraft booths with vertical air flow (top to bottom) are
considered state of the art because they provide the cleanest
drying/curing environment.10 Incoming air in a downdraft booth
is pulled in through filters in the roof, travels down over the
top of the vehicle, picks up coating solvent and overspray, and
passes into a grate-covered pit in the floor of the booth. The
downdraft booth is a better design than the crossdraft booth
because the air is less turbulent, which helps minimize overspray
in the rest of the booth. In addition, air circulation is more
uniformly concentrated around the vehicle and solvent vapor is
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Make-up Air
Exhaust Trtneh
Downdraft
Make-up Air
1
. , i i i (
Semi-downdraft
i
1 I II 11
/I
i
Crossdraft §
3
5
Figure 2-1. Spray Booth Make-up and Exhaust Air Orientation
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drawn down and away from the worker's breathing zone.10
Downdraft booths also eliminate dead air space in corners, which
may be found in crossdraft booths. Downdraft booths can be dry-
or wet-filtration (waterwash). In wet-filtration booths, water
is used to capture overspray. Although some VOC's may also be
captured in the water, unless these VOC's are contained, there is
no evidence that suggests waterwash spray booths are any more
effective in controlling VOC emissions than dry-filtration spray
booths.
The semi-downdraft spray booth is a combination of
crossdraft and downdraft booths. In a semi-downdraft booth, the
air enters the booth through the ceiling and is exhausted at the
back of the booth. Air in semi-downdraft spray booths is more
turbulent than in downdraft booths but less turbulent than in
crossdraft booths.
As coatings are reformulated and the refinishing industry
moves away from lacquer coatings and toward higher-solids and
waterborne coatings, the shops that do not have spray booths are
expected to elect to purchase some type of spray booth. Shops
with crossdraft booths may even decide to switch to downdraft or
semi-downdraft booths.
In order to decrease the drying time after coating
application, most shops with spray booths use forced drying
systems. Smaller shops may use traveling ovens that can be
rolled out for use inside the booth after the vehicle has been
sprayed. Small, portable infrared units in various sizes are
also available either to warm cold metal surfaces prior to
coating application or to speed the drying time of spot and panel
repairs.
2.5 SPRAY EQUIPMENT
Current practice in the automobile refinishing industry is
to apply all coatings with hand-held airless spray guns. These
guns atomize the coatings into tiny droplets by means of air
pressure. The two basic types of spray guns are pressure feed
and suction feed. In a pressure feed spray system, the coating
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is contained in a pressure pot that is connected by hose lines to
the spray gun. Compressed air pushes the liquid out of the spray
gun nozzle. Pressure feed spray guns generally consume
significantly more coating than suction feed guns because of the
amount of coating required to fill the pressure pot and hose
lines.
In a suction feed gun, the rapid flow of air through the air
line above the cup creates a vacuum in the coating intake tube,
causing the coating to rise and mix with the air before exiting
the gun.
Based on available data it seems clear that some spray
equipment is likely to give better transfer efficiency (TE) than
others. Simply defined, TE is the ratio of the amount of coating
solids deposited onto the surface of the coated part to the total
amount of coating solids used. Increased TE has a number of
benefits. Since coating overspray releases the same amount of
solvent as the coating that adheres to the target, overspray
reductions result in VOC emission reductions. Less overspray
also benefits the refinisher. Solvent concentration in the booth
is reduced, and less time is spent applying coatings (because
more reaches the vehicle), and solvent used for cleanup of
overspray on other parts of the vehicle is reduced.
Additionally, a shop which uses high TE spray equipment uses less
coating, and therefore realizes a savings in coating cost. The
TE provided by a spray gun varies dramatically, however,
depending on many factors which include the configuration of the
surface being coated, the type of gun used, and the skill of the
operator.
2.5.1 Conventional Airless Sprav Guns
Conventional airless spray guns are the standard method of
applying coatings. Compressed air is supplied through an air
hose to a spray gun that atomizes the coating into a fine spray.
The pressure supplied to the fluid controls the coating delivery
rate, with typical pressures ranging from 5 to 25 pounds per
square inch (psi). The air pressure controls the degree of
tit.035
Draft NAPCTAC 11/91
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atomization, and is usually 30 to 90 psi. One of the major
problems with conventional airless spray is the overspray caused
by the high volume of air required to achieve atomization.
Reportedly, this overspray typically results in relatively poor
transfer efficiency. As shown in Figure 2-2, there are two basic
types of conventional spray guns. In syphon-feed guns, air
pressure is used to draw the coating up into the gun. Gravity-
feed guns, with the paint pot oriented above the gun, require
less air pressure to move the paint into the gun.
2.5.2 High-Volume. Low-Pressure Sprav Guns
High-volume, low-pressure (HVLP) spray guns use large
volumes of air under reduced pressure (10 or less psi) to atomize
coatings. Because the atomized spray is released from the gun at
a lower velocity than in conventional air spraying, its flight
path is shorter, the spray gun must be held closer to the surface
being painted, and the momentum of the spray particles is less,
thereby reducing the particles "bounce." As a result, higher
transfer efficiency can be achieved, with overspray reportedly
being reduced by 25 to 50 percent.11 This increase in transfer
efficiency can result in a large savings in the amount of coating
required to refinish a vehicle.
The air source in an HVLP spray system can be a turbine or a
standard air supply, both of which can be purchased to handle
multiple spray guns. The system's fluid passages are stainless
steel or plastic so that the spray guns are compatible with a
full range of coatings. Many HVLP spray systems are designed to
atomize high-, medium-, and low-solids coatings. When using HVLP
spray equipment, the refinisher must learn a new spray technique
to adjust to the different spray pattern.
High-volume, low-pressure spray guns may make colormatching
more difficult because the painter must move the gun faster to
avoid producing a thicker coat. This can make it more difficult
to apply increasingly thinner coats when blending or feathering.8
If increased film thickness results from the use of an HVLP spray
gun, the evaporation rate of solvent in the coating would
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Draft NAPCTAC 11/91
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Syphon-FMd
Gravity-Feed
Figure 2-2. Conventional Spray Equipment
-------
decrease, which will influence the positioning of the flakes in a
metallic coating. Thick vims can also cause splotching, which
occurs when solvent initi-^ly trapped in the thicker coating
escapes to the surface and causes a blemish.
Once a refinisher becomes experienced with HVLP guns,
however, these problems can be overcome, with a significant
savings in coatings and money, and no significant deterioration
in the quality of the refinished surface.
2.5.3 Electrostatic Sprav Guns
Electrostatic spraying uses a transformer to create an
electrical potential between the coating particles and the
surface of the vehicle. The charged coating particles are
electrically attracted to the surface, thus increasing transfer
efficiency. This application method is frequently used by OEM's.
Current designs use a pressure pot connected to the spray gun via
a hose, and appear impractical for the refinishing industry,
primarily because refinish facilities change coatings so often.
A large amount of coating is left in the hose that connects the
spray gun to the paint pot. This coating must be removed before
the next coating can be applied with the same gun. In addition,
the cost of electrostatic spray systems may be prohibitive for
body shops.8
2.6 EQUIPMENT CLEANING
Spray equipment can be cleaned manually or with any of
several types of gun cleaning systems specifically designed for
this purpose. Shops that do not have gun cleaning systems
usually rinse the outside of the spray gun, fill it with solvent,
and then spray the solvent either into the air or into a drum set
12 13
aside for spent solvent. ' Reportedly, no method is typically
used to control the evaporative emissions from the solvent which
is sprayed into the drum. Fifty-nine percent of all shops,
however, reportedly use some type of gun cleaning system.12'13
An enclosed gun cleaner or washer (Figure 2-3) consists of a
closed container (much like an automatic dishwasher with a door
or top that can be open and closed) fitted with hose connections.
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Figure 2-3. Typical Enclosed Gun Cleaner
-------
The spray gun is placed in the container, and hoses are connected
to the suction and discharge nozzles of the spray gun. Solvent
is pumped through the gun and falls back down into the cleaner's
solvent reservoir for recycle. Additionally, solvent is sprayed
onto the exterior of the gun. Solvent is recirculated through
the gun washer system until it is too contaminated for further
use.
A typical open gun cleaner, shown in Figure 2-4, consists of
a basin similar to a sink in which the operator washes the
outside of the gun under a solvent stream. The gun cup is filled
with solvent, the gun tip is placed into a canister attached to
the basin, and suction draws the thinner from the cup through the
gun. The operator then removes the cup, places the gun's suction
stem under the clean thinner spigot, pulls the trigger, and pumps
clean thinner through the gun. The resulting solvent spray
gravitates to the bottom of the basin and through a drain to a
reservoir that supplies solvent to the recirculation pump. The
recirculating solvent is changed when it no longer cleans
satisfactorily.
Waste solvents generated by spray equipment cleaning have
traditionally been disposed of by evaporation (via spraying into
the air or onto the ground, or placing in open pans or drums),
incineration, or reclaimed via distillation. Solvent can be
recycled either at the shop or at an off-site location. Off-site
solvent recyclers collect spent solvent from body shops, distill
it, and return clean solvent to the shops. Some companies
provide this service only for those shops that rent their gun
cleaning systems.
In-house recycling can be as simple as letting spent
solvents settle and decanting the "clean" thinner layer for reuse
to clean guns. This method is called gravity separation and is
used in gun cleaners where the purity of the thinner is not
critical. Some on-site distillation units produce more refined
solvent, which further reduces thinner costs and disposal fees.
The residue from these systems has been reported to be
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X
~
2
Figure 2-4. Typical Open Gun Cleaner
-------
incorporated into rust-proofing undercoat materials for
vehicles.1*
The use of solvent for gun cleaning can reportedly be
reduced by using plastic rather than metal paint pots on the
spray gun because paint is easier to clean from a plastic surface
than a metal one. In addition, some facilities use a small
plastic liner inside the paint pot to make clean up easier and
reduce solvent use. The paint-covered plastic liner is discarded
after each use and the paint pot remains essentially free of
paint.
2.7 SPECIAL CONSIDERATIONS
Emissions from the refinishing process are reduced by
keeping the size of the refinishing area as small as possible.
Using the proper types of coatings and adequately colormatching a
partial refinish job will prevent having to refinish a larger
area than necessary. Colormatching would be far less complex
(resulting in less solvent and coating needed for blending) if
OEM stylists reduced the number of color selections, reduced the
frequency with which new colors are introduced, and
discontinued/reduced the use of so-called "glamorous" (such as
metallic and "pearl") topcoats that make colormatching more
difficult. In addition, a reduction in the use of multiple-stage
topcoats for refinishing in favor of single-rstage topcoats could
be expected to decrease VOC emissions through reducing the film
thickness (amount of coating solids) which is applied.
During this study, coating manufacturers stressed the
importance of the "systems approach." The manufacturers claim
that a regulating agency must consider the coatings (pretreatment
wash primer, precoat, primer sealer, primer surfacer, and
topcoat) in combination rather than as individual products. The
coating manufacturers maintain that the coating warranties are
valid only when a shop uses one manufacturer's products to
refinish a vehicle and the products are used in the recommended
combinations. To apply one manufacturer's primer with another
manufacturer's topcoat will void any warranty. The reason, they
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y
say/l is that even within a given manufacturer's product line, not
all of the products are compatible with one another (i.e., not
all primer surfacers are compatible with all topcoats).
Manufacturers claim they do not have the resources or time to
devote to testing their products' compatibility with other
manufacturers' coatings. Acceptance of the "systems approach"
would, however, limit the regulating agency's ability to set
limits based on the lowest VOC coatings available in each
refinish coating category.
The best ways to prevent VOC emissions from automobile
refinishing are to: (1) reduce the number of collisions, and
(2) minimize the amount of damage that occurs in a collision.
Decreasing the number of collisions might be accomplished by
decreasing the number of vehicles on the road. Increased use of
mass transit and car pools could help accomplish this. Improving
driver safety through educational classes or requiring anti-lock
brakes on all vehicles might also reduce the number of
collisions. Requiring 5 mile-per-hour bumpers as opposed to
2 1/2 mile-per-hour bumpers can reduce the amount of damage that
may occur from a collision. Programs to decrease the number and
severity of accidents have obvious benefits which extend beyond
reductions in VOC emissions.
2.8 MODEL SHOPS
2.8.1 Model Shop Characteristics
In this section, hypothetical models of refinishing shops
are developed so that the national impacts of proposed control
options can be estimated. The results of the analysis of the
impacts on these model shops are extrapolated to the entire
industry. Model shops are used first in establishing "baseline"
VOC emissions, which are intended to represent the industry as it
currently exists.
Eight model shops were developed to represent the automobile
refinishing industry. Their parameters are: (1) number of
employees, (2) number of full and partial jobs (assumed to
average one-tenth of a car or 10 ft2) completed each year,
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(3) VOC content of coatings applied, and (4) the presence (or
absence) of automatic gun cleaners and spray booths. Table 2-1
presents the characteristics of the model shops. (New car
dealerships are not distinguished from other types of facilities;
the dealerships will fall into one of the eight categories,
probably as small- or medium-size shops that do mostly partial
refinish jobs rather than full jobs.) The percent of shops in
each category, number of employees, and number of jobs completed
per year were derived from two studies of the automobile
refinishing industry and the results of an industry survey.8'9,15
The model shops in Table 2-1 are not identical to any of the
shops identified in the sources, but rather reflect a combination
of their features.
In general, Model Shop A represents small shops that have
little capital (limited equipment) and few employees. Model
Shops B through G represent medium-size shops which vary in the
number of jobs completed each year and the type and variety of
equipment owned. They make up the majority of shops in this
industry, with some rather unsophisticated and others very
technologically sophisticated. Because of this diversity,
six different models were used to represent these shops. Their
distinguishing features are the types of equipment (spray booths,
and gun cleaners) and the coatings used (lacquers, enamels and
urethanes). The industry segment represented by each of the
medium-size shops models (B through 6) was derived based on
equipment and coating use distinctions. Model Shop H represents
the production shops that have a high volume of business, greater
than 10 employees, and at least one gun cleaner and spray booth.
2.8.2 Model shop Equipment
The presence or absence of automatic gun cleaning equipment
in the model shops was derived based on discussions with
representatives of two companies that supply coatings or
equipment to the refinish industry.16,17 Automatic gun cleaners
are thought to be present in 59 percent of all body shops.
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TABLE 2-1. MODEL SHOP CHARACTERISTICS
Equipment3
Number of Booths
Jobs/yr
Model
Shop
Percent
of Shops
Number of
Employees
Partial
Full
Gun
Cleaner
Down-
draft
Cross-
draft
A
10
<5
150
13
N
N
N
B
14
5-10
350
13
N
N
N
C
5
5-10
500
25
Y
N
N
D
10
5-10
750
25
N
N
Y
E
39
5-10
1,000
50
Y
N
Y
F
7
5-10
900
100
N
Y
N
G
5
5-10
1,250
100
Y
Y
N
H
10
>10
750
600
Y
Y
N
aN = Shop does not have equipment.
-------
Thus, Model Shops C, E, G, and H were assumed to have automatic
gun cleaners. Model Shop H, a volume shop, may have several gun
cleaners.
The incidence of spray booths in refinish shops, whether
crossdraft or downdraft, was derived from an industry survey, and
16
was generally confirmed by an industry contact. There was no
information in the literature on the number of shops with semi-
downdraft spray booths, but it is likely that these shops are
included in those reported as having downdraft booths. Model
Shops A, B, and C do not have spray booths; Shops D through H
have at least one.
No evidence was found that any domestic refinish shops have
abatement equipment. This is reflected in the delineation of the
model shops.
2.8.3 Coating Usage in the Model Shops
The types of primers and topcoats used by each model shop
were derived from information contained in several references and
are shown in Table 2-2.5,8,10 Each of the references contains
information on coating use by shop size and production level,
ranging from 100 percent lacquer use by small shops that have no
spray booths to approximately equal lacquer, enamel, and urethane
use by all shops. Information from these three references was
combined to represent shop coating usage.
Model Shops A and B were assumed to use lacquer coatings on
75 percent of all refinish jobs. The remaining 25 percent are
enamel coatings. For these two models which do not own a spray
booth, lacquer use is assumed because it is fast drying and can
be buffed to remove surface imperfections.
Model Shop C is somewhat more technically advanced than
Models A and B, and a smaller percentage of vehicles are
refinished with lacquer coatings. Model Shop C completes 40
percent of the refinishing jobs with lacquer coatings, 30 percent
with enamels, and 30 percent with urethanes. Urethane coatings
reportedly produce the highest quality and most durable finishes.
Model Shops D and E use crossdraft spray booths to reduce dirt
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TABLE 2-2. COATING USE BY MODEL SHOP*
Model shop Lacquer Enamel Urethane
A 75 25 0
B 75 25 0
C 40 30 30
D 33 33 33
E 33 33 33
F 15 25 60
G 0 25 75
H 0 25 75
aPercent of vehicles refinished with each coating type.
-------
and dust levels in the painting area; these facilities are
assumed to refinish equal numbers of vehicles with lacquer,
enamel, and urethane coatings.
Downdraft booths provide the most dust-free environment,
thus making it easier for Model Shops P, G, and H to use slower
drying urethane coatings on more vehicles. Model Shop F is
presumed to use lacquers on 15 percent of the vehicles
refinished, enamels on 25 percent, and urethanes on 60 percent.
Model Shops G and H use enamels on 25 percent of their jobs and
urethanes on the rest.
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2.9 REFERENCES
1. U.S. Environmental Protection Agency. Control of Volatile
Organic Emissions from Existing Stationary Sources -
Volume VI: Surface Coating of Miscellaneous Metal Parts and
Products. EPA-450/12-78-015. U.S. Environmental Protection
Agency, Research Triangle Park, North Carolina. 1978.
2. Comments on the Memorandum: Summary of Automotive
Refinishing Model Shop Emission Reduction Costs prepared by
Radian Corporation for the U.S. Environmental Protection
Agency, from Randall, D.A., Automotive Service Association,
to Ducey, E., U.S. Environmental Protection Agency.
June 27, 1991.
3. Memorandum from Campbell, D.L., Radian Corporation, to
Ducey, E., U.S. Environmental Protection Agency. Revised
Trip Report of Site Visits with Sherwin-Williams Sales
Manager, Doug Smith. June 19, 1990.
4. PPG Refinish Manual. PPG Industries. 1989.
5. Bay Area Air Quality Management District. Staff Report on
Proposed Regulation 8, Rule 45 - Motor Vehicle and Mobile
Equipment Coating Operations. May l, 1989.
6. Letter from Schultz, K., E.I. DuPont de Nemours 6 Company,
Inc., to Gary Brower, New Jersey Department of Environmental
Protection. January 24, 1989.
7. Surface Coating of Plastic Parts Control Techniques
Guideline. Draft Chapter 3. U.S. Environmental Protection
Agency, Research Triangle Park, North Carolina.
December 13, 1990.
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8. Athey, C., C. Hester, M. McLaughlin, R.M. Neulicht, and M.B.
Turner. Reduction of Volatile Organic Compound Emissions
from Automobile Refinishing. EPA-450/3-88-009. U.S.
Environmental Protection Agency, Research Triangle Park,
North Carolina. 1988.
9. Code of Federal Regulations. Pt. 60, App. A, Method 24 -
Determination of Volatile Matter Content, Water Content,
Density, Volume Solids, and Weight Solids of Surface
Coatings.
10. Babcox Publications. 1990 Annual Industry Profile. Body
Shop Business. June 1990.
11. Graco, Incorporated. Product Information. High Output HVLP
Sprayers. 1990.
12. Telecon. Soderberg, E., Radian Corporation with Kusz, J.,
Safety Kleen Corporation. January 8, 1991.
13. Telecon. Soderberg, E., Radian Corporation, with Schultz,
K., E.I. DuPont de Nemours & Company, Inc. January 10,
1991.
14. SCS Engineers, Inc. Waste Audit Study: Automotive Paint
Shops. Prepared for the California Department of Health
Services. 1987.
15. Radian Corporation. Economic, Energy, and Environmental
Impacts of Add-on VOC Controls on the Automobile Refinishing
Industry in New Jersey. Prepared for the State of New
Jersey Department of Environmental Protection. August 1987.
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16. Telecon. Campbell, D.L., Radian Corporation, with Schultz,
K., E.I. DuPont de Nemours & Company, Inc. December 12,
1990.
17. Telecon. Soderberg, E., Radian Corporation, with Kusz, J.,
Safety Kleen Corporation. January 19, 1991.
tla.033
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3.0 EMISSION CONTROL TECHNIQUES
3.1 INTRODUCTION
There are three principle sources of volatile organic
compound (VOC) emissions from automobile refinishing. Emissions
occur when the surface to be refinished is being prepared, during
application of the primers and topcoats, and during spray
equipment cleaning.
Efforts to control VOC emissions from automobile refinishing
can be categorized as:
• reformulation of surface preparation products and
coatings to lower VOC levels;
• improved transfer efficiency (TE) of spray equipment;
• use of gun cleaning equipment that recirculates gun
cleaning solvent;
• add-on control; and
• improved housekeeping practices and training programs.
Reformulation consists of changing from solventborne to
waterborne or higher-solids products. Improved TE results in a
decrease in the amount of coating [and solvent (VOC) emissions]
needed to complete a job. By using gun cleaning equipment that
recirculates solvent for several cleanings and controls
evaporative losses, solvent use and VOC emissions can be reduced.
Add-on control devices or processes considered for this industry
are incinerators, carbon adsorbers, and biofilters. Improved
housekeeping practices include using closed containers for
storing fresh and spent solvents. Training programs could be
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developed which are aimed at educating shop workers on ways to
reduce solvent and coating use.
Section 3.2 summarizes the information on lower VOC surface
preparation products that can be used as substitutes for
conventional surface preparation products, and Section 3.3
discusses the lower VOC primers and topcoats that can be
used in place of conventional coatings to reduce VOC emissions.
Gun cleaners are discussed in Section 3.4 and add-on controls are
discussed in Section 3.5. The use of improved housekeeping
practices and training programs to reduce VOC emissions is
discussed in Section 3.6.
3.2 EMISSION REDUCTIONS FROM SURFACE PREPARATION
Volatile organic compound emissions can be reduced during
surface preparation by using products with lower VOC levels.
Conventional surface preparation products have average VOC levels
of 6.4 pounds of VOC per gallon of product (lb VOC/gal) [767
grams of VOC per liter of coating (g VOC/2)].1 These products
use solvent as the active ingredient to remove grease and wax.
There are low-VOC surface preparation products available
that can be used in place of these solventborne products. The
active ingredient in lower VOC products is detergent rather than
solvent. The VOC level of these products is below 1.7 lb VOC/gal
(200 g VOCfl), including water.2,3 This represents a 73 percent
reduction in VOC's. The VOC content is reported including water
because surface preparation products are not coatings and
therefore have no coating solids to take into consideration.
Lower VOC surface preparation products reportedly work as well as
conventional products, but they must be allowed to sit longer on
the surface before being wiped off. Conventional surface
preparation products are wiped off almost immediately after being
applied.
3.3 EMISSION REDUCTIONS FROM COATING APPLICATIONS
Emissions from coating applications can be reduced by the
following methods: (1) applying coatings that have lower VOC
levels, (2) using spray equipment that has a higher TE so that
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less coating can be used to refinish the vehicle, and
(3) abatement of the emissions.
3.3.1 Lower VOC Coatings
Emission reductions from coating applications can be
achieved by requiring the use of lower VOC coatings. Information
on coatings with lower VOC levels was gathered through a survey
of the major manufacturers of automobile refinishing coatings
conducted by the U. S. Environmental Protection Agency (EPA) in
March of 1990.* Based on the industry survey, regulatory Options
1 and 2 have been developed which consist of VOC limits for each
coating category (pretreatment wash primers and precoats, primer
surfacers, primer sealers, and topcoats). The Option 1 VOC
coating limits were derived by evaluating the coatings in terms
of their availability and reported limitations. The products
were evaluated as components of coating "systems" because the
survey responses were provided as systems. For example, of the
pretreatment wash primer and precoat responses, products that can
meet the Option 1 VOC limits reportedly had relatively few
limitations associated with their use, and can be used in a
majority of the coating systems. The survey responses for primer
surfacers revealed a wide range in VOC content, with research and
development obviously geared towards the development of
waterborne products. In selecting the Option 1 VOC limit,
however, it appeared that current technology, as far as the
majority of coating systems is concerned, relies on the use of
higher-solids solventborne primer surfacers rather than
waterborne products. The Option 1 VOC limit for primer sealers
is the same as the VOC content of the baseline enamel and
urethane primer sealers currently in use by refinishing shops.
It appears that research and development for primer sealers is
also moving towards the development of waterborne products, but
that it lags behind the development of waterborne primer
surfacers.
The Option 1 VOC limit for topcoats can be met by current
technology for urethanes. Some of the topcoats that can meet the
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Option 1 VOC limit had the reported disadvantage of poorly
matching OEM colors (especially metallics), indicating that they
are best suited for complete vehicle refinishing jobs. Other
topcoats that can meet the Option 1 limit, however, had no such
limitation listed.
The Option 2 VOC coating limits, which are more stringent
than the Option 1 limits for all products except primer sealers,
were also derived from the survey of coating manufacturers. The
primary selection criteria for the Option 2 VOC limits was that
products were currently available that meet the limit, and some
of them can be used as coating systems that have no reported
limitations concerning colormatch with OEM colors. Obviously,
because the Option 2 limits are more strict than the Option l
limits, there are fewer coating systems currently available. The
Option 2 VOC limit for primer surfacers can only be met by
waterborne products. The survey responses from the manufacturers
indicated that there are currently available waterborne primer
surfacers that can be used in many coatings systems. For primers
sealers, the Option 1 and Option 2 VOC limits are identical
because the survey results indicated that not only is research
and development of waterborne primer sealers lagging behind that
of primer surfacers, but development of higher solids primer
sealers is also lagging.
In calculating VOC emission reductions from coatings, it is
important to take into consideration the solids content of each
coating. It is the solids content that determines the amount of
coating that will be used to apply a certain film build over a
given surface area. The solvent/solids ratio determines the voc
emission potential of a coating. Therefore, the VOC emission
reductions achieved through either of the two regulatory options
which have been developed (Options 1 and 2) are based on
differences in the solvent/solids ratio between conventional
coatings and the coatings which meet the limit specified in
either option.
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Table 3-1 presents the baseline, Option l, and Option 2
coating VOC levels that are used in Chapter 4.0 to compare VOC
emissions and emission reductions for each model shop. Other
options may still be developed if additional information is
provided to the EPA which indicates that lower VOC coatings are
achievable.
As discussed in Chapter 2.0, the coatings used by model
shops consist of combinations of lacquer, enamel, and urethane
coatings, and the baseline coating VOC levels reflect these
combinations of coating use. The coatings presented in Option l
represent those with the lowest VOC levels within each coating
category that can be combined into coating "systems" that the
manufacturer has stated can be expected to be able to match all
OEM colors. Option 2 coatings have more stringent VOC levels.
Products that can meet the Option 2 VOC levels are currently
available, and are expected to be able to achieve colormatch, but
are not as widely used as Option 1 coatings.
Pretreatment wash primers or precoats are the first coatings
applied to a surface that is being refinished. Based on current
technology, organic pretreatment wash primers and precoats
typically have VOC levels of 6.5 lb VOC/gal (780 g VOC/£) less
water and exempt compounds, as applied.3 Both control levels
(Option 1 and Option 2) for pretreatment wash primers are based
on primers with higher solids contents than conventional
products. Such coatings in the first control level, Option 1, .
would be limited to 6.0 lb VOC/gaL^^O^g V0C/£), as applied,
less water and exempt compounds /^40 Decent reduction in VOC. r
The second control level, Option zT^^uldlXim^t^these coatings to
5.5 lb VOC/gal (660 g VOC ft) as applied/V^O^nercent reduction
in VOC.
The primer surfacers currently used typically range from 4.8
to 5.7 lb VOC/gal (580 to 680 g VOC/t), as applied, less water
and exempt compounds. Option 1 would limit VOC levels to
3.8 lb VOC/gal (460 g VOC/4). The resulting reduction would
range from 40 to 70 percent. Option 2 would limit primer
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TABLE 3-1. VOC CONTENT OF BASELINE, OPTION 1, AND OPTION 2
COATINGS
Coating Category
VOC Content, (lb VOC/gal coating)
(Excluding water and exempt
solvents, as applied).8
Current
Technology
(Baseline)
Option 1
Option 2
Pretreatment Wash
Primers and Precoats
6.5
6.0
5.5
Primer Surfacers
4.8-5.7
3.8
2.1
Primer Sealers
4.6—5.6
4.6
4.6
Topcoats
5.2-6.0
5.2
4.5
aAs applied means that the coating includes the reducer and/or
hardener.
tl*.035
Draft NAFCTAC 11/91
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surfacers to 2.1 lb VOC/gal (250 g VOC/£), as applied. The
percent reduction resulting from this waterborne material would
range from 75 to 90.
Like primer surfacers, the primer sealers currently used for
automobile refinishing have a variety of VOC levels. Typically
they range from 4.6 to 5.6 lb VOC/gal (550 to 670 g VOC/l), as
applied, less water and exempt compounds. Option 1 would limit
the VOC levels to those at the lower end of the range in solvent
levels currently in use, 4.6 lb VOC/gal. As discussed above, the
coating manufacturers* research and development of waterborne
primer sealers lags behind that of primer surfacers. Thus,
Option 2 would have the same VOC limit as Option 1. Options 1
and 2 primer sealers would reduce VOC emissions by up to 55
percent.
As discussed in Chapter 2.0, topcoats are applied as a
single coating, two-stage (basecoat-clearcoat), or three-stage
(basecoat-midcoat-clearcoat). In order to compare these
different types of topcoats, current State regulations use the
following equation to calculate the total VOC content of a two-
stage topcoat:
VOCT =
X
VOCBC ~ 2 TOCcc
(3-1)
where:
VOCt
VOCbc
VOCcc
total VOC content
voc content of basecoat
VOC content of clearcoat
This equation is used because in a two-stage system, the basecoat
is normally one-third of the film build or coating volume used,
and the clearcoat is two-thirds of the film build.
To compare the VOC contents of three-stage coatings, the
following equation is used:5
tl».035
Draft NAPCTAC 11/91
-------
vocT
VOCBC + VOC^ + 2 VOCcc
(3-2)
4
where
VOCT
VOCbc
VOCmc
VOCcc
total VOC content
VOC content of basecoat
VOC content of midcoat
VOC content of clearcoat
This equation is used because in a three-stage system, the
basecoat and midcoat normally make up one-quarter of the film
build apiece and the clearcoat makes up one-half of the film
build.
Coating manufacturers support the use of these equations
because they provide them with the flexibility to reduce the VOC
content of certain "stages" or coats of the topcoat, to provide
an overall emission reduction. In some cases, it is argued that
a higher VOC stage may be necessary to protect a lower VOC stage.
Manufacturers suggest that lower VOC coating development would be
more limited if regulating agencies choose to establish limits
for each of the stages (basecoat, midcoat, clearcoat) separately.
A potential problem may exist with these equations which
"average" the VOC content of the different stages of the topcoat.
Based on information gathered during this study, it appears that
clearcoats tend to have much lower VOC contents (higher solids)
than basecoats. Given this fact, twice as much clearcoat as
basecoat would not be needed to cover a given surface area. The
equations may give a greater weighting to the lower VOC
clearcoats than is deserved, although the effect may not be
significant. For the case of waterborne coatings, adjustment
will need to be made to these equations since the VOC content is
expressed "less water" and does not represent an actual gallon of
coating.
The average VOC contents of the topcoats now used by the
industry range from 5.2 to 6.0 lb VOC/gal (620 to 720 g VOC/I),
tls.035
Draft NAPCTAC 11/91
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as applied, less water and exempt compounds. The Option 1 limit
for topcoats would be 5.2 lb VOC/gal (620 g VOC/I), as applied,
less water and exempt compounds, and would reduce emissions by up
to 52 percent. The Option 2 limit would be 4.5 lb VOC/gal (540 g
VOC/£). The industry survey indicated that some topcoats with
these VOC levels are currently available. Emission reductions
would range from 40 to 70 percent.
3.3.2 Hiah-Transfer-Efficiencv Sorav Equipment
Although TE is a simple concept, it is difficult to use for
regulatory purposes because of its variability. It is highly
dependent on factors such as the type of coating used, the shape
of the part being refinished, and operator skill. As a
consequence, the use of TE as a quantifiable VOC control method
will not be included in this Control Techniques Guideline (CTG).
Since higher TE results in decreased paint usage, a State may
choose to publicize the benefits of use of certain spray
equipment to decrease the amount of money a shop may spend on
paint.
3.3.3 New Developments in Sprav Equipment
Several manufacturers are currently developing new types of
spray equipment that may be feasible for use by automobile
refinishers in the future. One such development uses
supercritical carbon dioxide as a substitute for a large portion
of the solvent normally required for the spray application of
coatings. Another type of spray equipment reportedly improves TE
and provides constant spraying pressure by using encapsulated
nitrogen gas rather than compressed air to atomize the coating.
3.4 EMISSION REDUCTIONS FROM GUN CLEANING
Gun cleaning is a major source of solvent emissions. As
discussed in Chapter 2.0, spray equipment can be cleaned manually
with no control of evaporative emissions or with gun cleaning
equipment designed to reduce solvent consumption, evaporation,
and worker exposure. In general, a gun cleaner can be defined as
an automatic system that washes the spray gun, recirculates
tli.035
Draft HAJPCXAC 11/91
-------
solvent for several washings, and minimizes solvent (VOC)
evaporation. Depending on the method used, solvent may be
emitted both during the actual cleaning operation (active losses)
and during standby (passive losses).
The recirculated solvent from a gun cleaner is replaced when
it no longer cleans the guns satisfactorily. An emission
reduction of 88 percent from gun cleaning can be achieved for a
shop that adds a gun cleaner and delivers the spent solvent to a
reclaimer.
Gun cleaners can be enclosed or open. A report obtained
during this study indicates that open gun cleaners emit no more
VOC than enclosed gun cleaners.6 This report is based on
comparisons of passive and active VOC losses from four models of
open gun cleaners manufactured by the same company with five
enclosed units manufactured by other companies. From this study
it appears that if enclosed gun cleaners could be designed to
control evaporative emissions when the lid is opened (to insert
and remove the gun for cleaning), and so that the hoses which
recirculate the solvent do not leak, they may be preferred over
the open design.
3.5 ADD-ON CONTROLS
Add-on controls remove VOC from the solvent-laden spray
booth exhaust. They can be used in a wide variety of VOC
emitting industries, and can be grouped into two broad
categories: (1) destructive (usually combustion devices), and (2)
recovery devices. Recovery devices include those that adsorb,
scrub, or condense solvent and other VOC from the air.
One destructive method which has recently been receiving
attention in the air pollution control community is
biofiltration, which involves passing the VOC-laden air stream
through a biologically active material such as compost.
3.5.1 Incineration
Incineration converts VOC to carbon dioxide and water.
Incinerators are of two major types, thermal and catalytic.
Thermal incineration co-fires the fuel (usually natural gas) with
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Draft NAPCTAC 11/91
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the exhaust stream to destroy VOC. The amount of fuel required
depends on the VOC concentration (i.e., fuel values) of the
exhaust stream. Figure 3-1 is a schematic of a typical thermal
incinerator. Heat recovery is optional. The incinerator is a
refractory-lined combustion chamber containing the fuel burner.
The VOC-laden exhaust stream enters the combustion chamber where
it is heated by the burner flame. The destruction efficiency is
generally limited only by the cost of fuel, although for
practical purposes the outlet concentration will stabilize at
about 20 ppm. The chamber must be sized for the air flow so that
there is sufficient residence time and mixing for the VOC
oxidation reaction to reach completion. Incoming exhaust air- can
be preheated in the optional heat exchanger. To increase thermal
efficiency and reduce auxiliary fuel requirements many companies
purchase a heat exchanger to preheat the incoming air.
The three main parameters that affect the destruction
efficiency of an incinerator are temperature, residence time, and
gas mixing. Firing temperatures for incinerators range from
1,300 to 2,350°F (700 to 1290°C).
Figure 3-2 shows a typical catalytic incinerator with
optional heat recovery. The catalyst causes the oxidation
reaction to take place at a lower temperature, typically from 600
to l,200°F (316 to 649°C), which results in lower (and sometimes
no) auxiliary fuel costs. Combustion catalysts include platinum,
platinum alloys, copper oxide, chromium, and cobalt which are
deposited in a thin layer on an inert substrate.7 Catalytic
incinerators can achieve VOC destruction efficiencies approaching
those of direct incinerators. Although it has a higher capital
cost, and the expensive catalyst has to be replaced due to aging
or poisoning, the savings in fuel requirements often reduce
operating costs sufficiently to offset these costs. The exhaust
stream fed to a catalytic incinerator must be filtered to prevent
any occluded matter from plugging the catalyst.
Us. 035
Draft NAFCTAC 11/91
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Stack
Burner piata
Flam* Jala
Optional haat
racovary
Figure 3-1. Direct Thermal Incinerator
-------
To ctmo«ph«r»
•tack
Fan
Figure 3-2. Catalytic Incinerator
3-13
f
-------
3.5.2 Carbon Adsorption
For automobile refinishing, with relatively low
concentrations of VOC in the spray booth exhaust stream (from 100
to 1500 ppm), the recovery process that is the most technically
feasible is carbon adsorption. In a carbon adsorption system,
the exhaust stream passes through an activated carbon bed where
the carbon particles adsorb VOC. Removal efficiencies can be 95
percent and greater.8
When the carbon becomes saturated, the system has reached
breakthrough. This is measured by a decrease in removal
efficiency or an increase in pressure drop across the bed. At
this point the carbon must be desorbed or regenerated. The
desorption process passes heated air or steam through the bed,
which removes the VOC from the surface of the carbon particles.
The desorbed solvent is recovered through cooling and
condensation. It can then be purified or used as waste fuel.
Automobile refinishing shops may not have access to the
steam or cooling water required for carbon desorption. In these
cases, the saturated carbon could be desorbed off-site by the
carbon supplier, who would replace the saturated carbon with
fresh carbon.
A potential problem with the use of carbon adsorbers may be
the varying VOC concentration of the booth exhaust air stream.
Concentrations are relatively high while a car is being coated
(1500 ppm) and tapers off during forced drying (100 ppm).
Desorption of the captured VOC's may occur when heated and
lower-VOC spray booth air passes through the carbon, resulting in
lower removal efficiencies. Alternatively, the carbon bed may be
bypassed when the VOC concentration reaches a minimum level.
In industrial facilities, a carbon bed must be desorbed
several times daily. However, in an automobile refinishing
facility, where painting is done only a few hours daily,
regeneration (or carbon replacement) may take place less than
once per month. Long periods between carbon replacements would
increase the likelihood of desorption during periods of non-use.8
tia.03S
Draft NAFCTAC 11/91
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Ketones, one of the primary solvents in automobile refinish
coatings, require special operating conditions to offset their
high heat of adsorption.9 The sophistication level needed may
make carbon adsorption impractical or too expensive for auto
refinish shops.
3.5.3 Biofiltration
Biofiltration is currently being used at several sites
including coating facilities, foundries, and food processing
operations. Volatile organic compound control efficiencies of
over 90 percent have been reported.10 In a biofiltration system,
the VOC-laden exhaust stream is humidified and passed through a
biologically active bed such as compost, wood chips, municipal
waste, or other organic material. The VOC's diffuse into the
compost and are destroyed by aerobic biodegradation. Bacterial
microorganisms convert the VOC's into carbon dioxide and water.
The filter material must be replaced after a few years, and is
not considered a hazardous waste.
Capital and operating costs of biofiltration systems are
reportedly lower than those of incineration and carbon
adsorption. Biofiltration is also well suited to control
airstreams with low VOC concentrations typical of the exhaust
from automobile refinishing spray booths. Thus, biofiltration
may be a cost-effective alternative for VOC control in the
automobile refinishing industry.10
3.6 EMISSION REDUCTIONS FROM IMPROVED HOUSEKEEPING PRACTICES AND
TRAINING PROGRAMS
In addition to the emission reduction techniques already
described above, solvent evaporation can be minimized through
diligent housekeeping practices. By storing fresh and spent
solvent in containers designed to minimize vapor loss and
minimizing the amount of time that solvent is exposed to the
atmosphere, shops can save money as well as reduce VOC emissions.
Coating waste can be minimized by mixing only as much coating as
is needed to complete a refinish job. Waste paint, spent
solvent, and sludge from gun cleaners and in-house distillation
tls.035
Draft NAPCTAC 11/91
-------
units should be disposed of properly by transfer to designated
hazardous waste management facilities. A manifest system will
aid the local agency in enforcement activities.
Solvent use should be minimized to prevent evaporation.
Shops that clean the walls of their spray booths can do so by
using products made specifically for this purpose that do not
contain VOC's. Several companies market a waterborne stripable
coating designed for spray booths. At intervals, the old coating
is pulled off the booth walls, simultaneously removing overspray
that has deposited on the booth walls. A fresh coat is then
applied. This process change can almost eliminate the need for
solvent in cleaning booths.
Coating use (and costs) and VOC emissions can also be
reduced through training programs that teach good work practices.
These programs could recommend the use of high TE spray
equipment, inform refinishers of the importance of minimizing
overspray, and teach methods by which colormatch can be achieved
without extensively diluting the coating with additional solvent.
Training programs can also help refinishers select the correct
types of coatings to use on certain substrates and in certain
conditions (i.e., varying temperature or humidity) so that a job
does not have to be redone.
3.7 SUMMARY OF EMISSION CONTROL TECHNIQUES
Reductions in VOC emissions can be achieved by: using
waterborne surface preparation products in place of solventborne
products to clean vehicles, using waterborne or higher solids
coatings (which have a higher solids-to-solvent ratio) in place
of conventional products, and using spray gun cleaners that
recirculate solvent and minimize solvent evaporation. Add-on
controls can also be used to destroy or recover VOC's from the
spray booth exhaust stream. In addition, training programs for
body shop workers on use of lower VOC coatings, control
equipment, and on housekeeping practices which minimize solvent
evaporation, can help make regulations more effective.
tls.035
Draft NAFCTAC 11/91
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To achieve VOC reductions from coatings, two VOC levels have
been delineated for each coating category. Current lower VOC
technology is mostly higher solids, although waterborne primers
and basecoats are currently available. Add-on controls
considered for this industry are incineration, carbon adsorption,
and biofiltration. These devices remove VOC from the spray booth
exhaust stream which contains solvent concentrations that
typically range from 100 to 1500 ppm.
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3 .8 REFERENCES
1. Letter from Ocampo, G.P., The Sherwin-Williams Company, to
Ducey, E., U.S. Environmental Protection Agency.
October 30, 1990.
2. South Coast Air Quality Management District, staff Report
on Proposed Rule 1151—Motor Vehicle and Mobile Equipment
Non-Assembly Line Coating Operations. June 16, 1988.
3. State of California Air Resources Board. Determination of
Reasonably Available Control Technology and Best Available
Retrofit Control Technology for Automobile Refinishing
Operations. January 8, 1991.
4. Memorandum from Campbell, D.L., Radian Corporation, Research
Triangle Park, NC, to Ducey, E., U.S. Environmental
Protection Agency, Research Triangle Park, NC. Summary of
Coating Manufacturer's Survey Responses — Automobile
Refinishing CTG. February 28, 1991.
5. Bay Area Air Quality Management District. Staff Report on
Proposed Regulation 8, Rule 45—Motor Vehicle and Mobile
Equipment Coating Operations. May 1, 1989.
6. ENSR Consulting and Engineering. Comparison of Solvent
Emissions from Two Types of Spray Gun Cleaning Systems.
Prepared for Safety-Kleen Corporation. ENSR Document
No. 5831-005800. March 1990.
7. U. S. Environmental Protection Agency, OAQPS, Organic
Chemical Manufacturing Volume 4: Combustion Control Devices.
Report 4. Publication No. EPA-450/3-80-026. December 1980.
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Draft NAPCTAC 11/91
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8. Radian Corporation. Economic, Energy, and Environmental
Impacts of Add-on VOC Controls on the Automobile Refinishing
Industry in New Jersey. Prepared for the New Jersey
Department of Environmental Protection. August 1987.
9. Letter and attachments from Ellam, E.G., Calgon Carbon
Corporation to Barbour, Wiley, Radian Corporation.
March 12, 1990.
10. RMT Network. Air Pollution Control Costs May Be Reduced
with Biotechnology: Biofiltration Provides Environmentally
Benign Solutions.
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Draft NAPCTAC 11/91
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4.0 EMISSION ESTIMATION TECHNIQUES
This chapter discusses volatile organic compound (VOC)
emissions and emission reductions that can be achieved with the
use of the control technologies described in Chapter 3.0. The
emissions and emission reduction estimates are calculated using
the model shops presented in Chapter 2.0. Appendix B presents
the emission estimation techniques in more detail.
Volatile organic compound emissions from automobile
refinishing occur (1) when the surface to be refinished is being
prepared, (2) during application of the coatings (primers and
topcoats), and (3) during spray equipment cleaning. Emission
reduction estimates from each of these processes are discussed
below. These reductions are somewhat conservative. They assume
that all complying products have VOC levels that exactly meet the
required VOC levels. In reality, some will have lower VOC
levels, but the incremental reductions are not reflected in the
emission reduction estimates.
4.1 SURFACE PREPARATION
4.1.1 pasaline Volatile Organic Compound Emissions from Surface
Preparation
To calculate the VOC emissions from the surface preparation
operation, all model shops were assumed to use products with VOC
levels of 6.4 lb VOC/gal (780 g VOC/I) on average.1 For each
full vehicle prepared for refinishing (about 100 ft2 of surface),
1.5 pints (0.7 £) of preparation products are used. For each
partial job, it is assumed that about one-tenth the surface area
is prepared (10 ft2), using 0.15 pints (0.07 I) of surface
preparation product. The assumed surface areas of full and
partial refinish jobs are averages only. If the actual surface
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Draft NAFCTAC 11/91
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area of a refinish job is known, it can be used in the following
equations.
The VOC emissions from surface preparation for each model
shop are calculated by first estimating the total surface area
prepared for refinishing in 1 year and the amount of surface
preparation product used. Surface area is calculated with the
following equation:
A = (FJ * 100) + (PJ * 10) (4-1)
where:
A = surface area coated per year (ftz/yr)
FJ * full jobs completed per year
100 = area coated per full job (ft2/full job)
PJ = partial jobs completed per year
10 = area coated per partial job (ft2/partial job)
The amount of surface preparation product used by a shop in
one year is calculated as:
SP = A * 0.015/8 (4-2)
where:
SP = annual surface preparation product usage (gal/yr)
A = total automobile surface area prepared per year
(ft2/yr)
0.015 » pints of surface preparation product used per
square foot
8 ¦ pints per gallon
To calculate the total annual emissions from surface
preparation products, the following equation is used:
tls.035
Draft NAPCTAC 11/91
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Egp = SP * Csp (4-3)
where:
Esd = annual VOC emissions from surface preparation
* (lb/yr)
SP = annual surface preparation product usage (gal/yr)
csp = voc content of surface preparation product
(lb VOC/gal product)
Table 4-1 presents the amount of surface preparation product
used and total baseline VOC emissions from surface preparation
for each model shop.
4.1.2 Reduction nt VOC from Surface Preparation Operation
The use of surface preparation products with lower VOC
levels will reduce VOC emissions. As discussed in Chapter 3.0,
waterborne surface preparation products with VOC levels below
1.7 lb VOC/gal (200 g V0C/£) including water are currently
available and reportedly are as effective as conventional
products when an equal amount is used (1.5 pints/full car). The
emissions and emission reductions that occur with the use of
these products were calculated with Equation 4-3.
Table 4-1 shows the surface preparation VOC emissions and
emission reductions for each model plant if it transitions to
lower VOC surface preparation products.
4.2 COATING APPLICATIONS
4.2.1 Baseline VOC Emissions from Coating Applications
In estimating emissions from applying a coating, the
assumption is made that all of the coating mixed for the job is
sprayed, and therefore no emissions are attributed to waste
paint. To estimate the amount of coating applied by each model
shop, Equation 4-1 was first used to calculate the surface area
refinished per year. Unlike the case with surface preparation
products, where each model shop is assumed to use products with
the same average VOC content, the VOC content of the various
primers and topcoats used by different model shop are not the
tls.033
Draft NAPCTAC 11/91
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TABLE 4-1. SURFACE PREPARATION EMISSIONS AND EMISSION REDUCTIONS
Model
shop
Surface
preparation
product
usage
(gal/yr)
Surface Preparation
VOC Emissions3
(lb/vr)
Conventional Lower VOC
Emissions
reduction
(lb/yr)
A
5. 3
34
9
25
B
9.0
58
15
43
C
14 .1
90
24
66
D
18 .8
120
32
88
E
28.1
180
48
132
F
35.6
228
60
168
G
42.2
270
72
198
H
126.6
810
215
595
aVOC Content of Surface Preparation Product:
Conventional * 6.4 lb/gal
Lower voc « 1.7 lb/gal
-------
same. The model shops are presumed to have different levels of
technological sophistication. As discussed in Chapter 2.0, Model
Shops A and B were presumed to use primers and topcoats with the
highest average VOC levels and Model Shops G and H use those with
the lowest average VOC levels.
The average VOC content of the four coatings used by each
model shop is shown in Table 4-2. Solids content was calculated
by the following equation:
Vs - l-(VOC/d) (4-4)
where:
Vg = volume solids content of coating (fraction)
VOC « VOC content of coating (lb VOC/gal coating)
d = density of solvent (lb solvent/gal solvent)
Typical solvent density was assumed to be 7.3 lb/gal. 2 The
fractional volume of solvent subtracted from 1 gives the
fractional volume of solids in the coating.
To calculate the amount of coating used for each model shop
and the associated VOC emissions, the total volume of dry film,
(calculated by multiplying surface area times dry film thickness)
was calculated to estimate the amount of coating solids that will
be used. Dry film thickness is defined as the amount of coating
deposited on a surface, and is measured in mils, or 1/1000 inch
(0.02 mm).3 The film thicknesses assumed to be required for
each coating were:*
Pretreatment Wash Primer (Precoat): 1.00 mil
Primer Surfacer: 2.25 mils
Primer Sealer: 1.75 mils
Topcoat: 3.50 mils
Total dry film coating thickness of automotive finishes is 5 to
10 mils, depending on the types of coatings used. The solids
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Draft HAPCTAC 11/61
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TABLE 4-2. BASELINE MODEL SHOP COATING EMISSIONS
Model
shop
VOC content of paint
(lb VOC/gal •*
applied)"4®*0'®
Solids content
as applied
(X)
Coating use
per coaplete car
(gat/car)
Coating use per year
(gal/yr)
VOC emissions per year
(ton/yr)
Specialty Products
VOC emissions
Use per year per year
(gal/yr) (ton/yr)
A
t.
6.5
11
1.6
45.5
0.15
12.6
0.04
2.
5.7
22
2.0
55.5
0.16
3.
5.6
22
1.5
42.7
0.12
4.
6.0
17
3.8
107.4
0.33
B
1.
6.5
11
1.6
78.0
0.25
21.5
0.08
2.
5.7
22
2.0
95.1
0.28
3.
5.6
22
1.5
73.1
0.21
4.
6.0
17
3.8
184.0
0.56
C
1.
6.5
11
1.6
121.9
0.40
28.2
0.10
2.
5.3
28
1.6
120.2
0.33
3.
5.2
29
1.2
90.4
0.24
4.
5.7
22
3.1
231.3
0.67
D
1.
6.5
11
1.6
160.9
0.52
35.9
0.13
2.
5.1
29
1.5
151.5
0.41
3.
5.0
31
1.1
113.4
0.30
4.
5.5
24
2.9
291.6
0.83
E
1.
6.5
11
1.6
241.4
0.78
53.8
0.19
2.
5.1
29
1.5
227.3
0.61
3.
5.0
31
1.1
170.1
0.45
4.
5.5
24
2.9
437.4
1.26
f
1.
6.5
11
1.6
308.8
1.00
61.5
0.22
2.
5.0
32
1.3
253.1
0.65
3.
4.8
34
1.0
186.0
0.46
4.
5.4
26
2.5
481.5
1.32
G
1.
6.5
11
1.6
365.7
1.19
65.8
0.23
2.
4.8
34
1.2
263.3
0.63
3.
4.6
37
0.8
189.6
0.44
4.
5.2
28
2.2
497.0
1.30
H
1.
6.5
11
1.6
1,097.2
3.57
197.4
0.69
2.
4.8
34
1.2
789.9
1.90
3.
4.6
37
0.8
568.9
1.31
4.
5.2
28
2.2
1,491.0
3.91
a1. = Pretreatment Wash Primer or Precoat; 2. = Primer Surfacer; 3. = Primer Sealer; and 4. - Topcoat
^Excluding water and exempt solvents.
cAs applied means the coating includes the reducer and/or catalyst.
-------
content of the coating determines the wet volume of coating
necessary to provide the desired dry film thickness. Coating
usage was calculated as:
C « [Sa * A * t]/[1604 * Vs * TE] (4-5)
where:
c - annual coating usage (gal/yr)
Sa = fraction of surface area covered by coating
A » surface area coated per year (ft2/yr)
t ® dry coating film thickness (mils)
1604 * area that 1 gallon of coating solids can cover to
1 mil thickness (ft2 * mil/gal)
Vs = volume solids content of coating (fraction)
TE » transfer efficiency (fraction)
As discussed in Chapter 2.0, TE is a measure of efficiency of the
application method. Specifically, it is the ratio of the coating
solids deposited onto the surface of the coated part to the total
amount of coating solids used. To compare VOC emissions and
emission reductions for the model shops, the TE for all coating
applications was assumed to be 35 percent. The actual efficiency
achieved in any situation is the result of a host of variables
including the size and shape of the object coated, painter skill,
type of coating being applied, surrounding air currents and
velocities, and type of spray equipment.
Equation 4-5 was used to find coating usage for the entire
coating system (all four coatings). Emissions for each solvent-
borne coating were calculated by:
Ec C * VOC (4-6)
where:
Ec ¦ annual emissions from coating (lb VOC/yr)
tls.033
Draft NAPCTAC 11/91
-------
C = annual coating usage (gal/yr)
VOC = VOC content of coating
(lb VOC/gal coating)
For waterborne coatings, emissions are calculated as:
Ewc ~ cw * t1 ~ wv) * V°C (4-7)
where:
EWc ~ annual emissions from waterborne coating (lb/yr)
Cw = annual waterborne coating usage (gal/yr)
Wv = volume fraction water
VOC - VOC content of coating (lb VOC/gal coating)
The columns in Table 4-2 for "specialty products" show the
gallons used by each model plant and the VOC emissions from the
use of these products. The baseline VOC assumes these products
have a VOC content of 7.0 lb VOC/gal (840 g VOC/£) and they are
used at a rate equal to 5 percent of the liquid volume of all
coatings applied on a daily basis.3 As discussed in
Chapter 2.0, these products are reportedly necessary to achieve
specific performance requirements. They are added to a finish in
relatively small amounts to impart or improve desirable
properties such as gloss or flexibility.
4.2.2 Reduction of Volatile Organic Compound Emissions from
Coating Applications
Chapter 3.0 explained that improvements in TE are too
difficult to measure or enforce and therefore will not be
recommended as a regulatory tool, although certainly improvements
benefit both the shop owner and the environment. Thus, emissions
reductions from coating application are limited to coating
reformulation (such as Option l and 2) or abatement. For the
purposes of this study, emissions from waste coating disposal are
not considered.
tl».033
Draft NAPCTAC 11/91
-------
Table 4-3 presents two reformulation options. The "coating
use per car" column reflects that use of coatings with higher
solids content reduces the volume of wet paint required to
refinish a car. The percent solids and coating use are
calculated as shown in Equations 4-4 and 4-5 above. The same
total volume of dry film is assumed whether conventional,
Option 1, or Option 2 coatings are used. Tables 4-4 and 4-5
present the VOC emission reductions that can be achieved by each
model shop using the Option 1 and 2 coatings. These emissions
were calculated as shown in Equation 4-6 above.
Table 4-6 summarizes the total coating usage, total VOC
emissions, and total emission reductions that can be achieved
with the use of lower VOC coatings.
4.3 GUN CLEANING
4.3.1 Baseline volatile Organic Compound Emissions from Gun
Cleaning
Emissions from gun cleaning at the model shops will depend
on whether the shop has automated gun cleaners. Model Shops A,
B, D, and F do not have gun cleaners. It has been assumed that
their guns are cleaned by spraying solvent into a container
without regard for evaporative losses. Emissions were calculated
by assuming that 10 ounces (283 g) of solvent were used to clean
each gun, and that in each partial and full refinishing job the
gun will be cleaned an average of four times. It was assumed
that all of the solvent used to clean guns would evaporate at
those shops which do not use gun cleaners. The annual emissions
from shops without gun cleaners were calculated by the following
equation:
Eb - TJ * 4 * 10/16 (4-7)
where:
TJ
Eb »
annual gun cleaning emissions from a shop which
does not use a gun cleaner (lb/yr)
total number of refinish jobs per year
tU.035
Draft HAPCTAC 11/91
-------
TABLE 4-3. OPTION 1 AND 2 COATING CHARACTERISTICS
Coating
Option
VOC content
as applied
(lb VOC/gal
coating)a/^
Solids content
as applied
<%>c
Coating use
per car
(gal/car)
Pretreatnent
Baseline
6.5
11
1.6
Wash Primer
(Precoat)
Option 1
6.0
18
1.0
Option 2
5.5
25
0.7
Primer Surfacer
Baseline
r*
•
in
CO
•
34-22
1.2-2.0
Option 1
3.8
48
0.8
Option 2
2.1
44
0.9
Primer Sealer
Baseline
4.6-5.6
37-22
0.8-1.5
Option 1
4.6
37
0.8
Option 2
4.6
37
0.8
Topcoat
Baseline
5.2-6.0
29-17
1.8-3.8
Option 1
5.2
29
1.8
Option 2
4.5
38
0.8
aExcluding water and exempt solvents.
bAs applied means the coating includes the reducer and/or hardener.
-------
TABLE 4-4. VOC EMISSION REDUCTIONS FROM COATINGS (OPTION 1)
Reduction
Total reduction
from baseline
from baselire
Model
Paint use per year
VOC emissions per year
coating emissions
coating emissnrs
shop
(gal/yr)a
(ton/yr)
(X)
m
A
1.
28.0
0.08
43
55
2.
23.4
0.04
72
3.
23.6
0.05
56
4,
60.7
0.16
52
8
1.
48.0
0.14
43
55
2.
40.1
0.08
72
3.
40.5
0.09
56
4.
104.0
0.27
52
C
1.
75.0
0.23
43
44
2.
62.7
0.12
64
3.
63.2
0.15
41
4.
162.5
0.42
37
0
1.
99.0
0.30
43
42
2.
82.S
0.16
61
3.
83.4
0.19
36
4.
214.6
0.56
34
E
1,
148.5
0.45
43
42
2.
124.1
0.24
61
3.
125.2
0.29
36
4.
321.8
0.84
34
F
1.
190.1
0.57
43
33
2.
158.8
0.30
53
3.
160.1
0.37
20
4.
411.8
1.07
19
G
1.
225.1
0.68
43
23
2.
188.1
0.36
43
3.
189.6
0.44
0
4,
487.6
1.27
0
H
1.
675.2
2.03
43
23
2.
564.3
1.07
43
3.
568.9
1.31
0
4.
1,462.9
3.80
0
a1. ¦ Pratraatmant With Primar op Pracoat; 2. ¦ Primer Surfacer; 3. » Primer Saalar; and 4. » Topcoat.
-------
TABLE 4-5. VOC EMISSION REDUCTIONS FROM COATINGS (OPTION 2)
Reduction Total reduction
from baseline from oasei^e
Model
shop
Paint use per year
-------
TABLE 4-6. TOTAL VOC EMISSION REDUCTIONS WITH LOWER VOC COATINGS
Emission Reductions
fton/yr)
Total Coating Usagea Total VOC Emissions Option l Option 2
Model
faal/vr)
fton/vrl
over
over
shop
Baseline
Option 1
Option 2
Baseline
Option 1
Option 2
baseline
baseline
A
251.0
135.7
92.4
0.76
0.34
0.18
0.42
0. 58
B
430.3
232.6
158.4
1.31
0. 58
0.31
0.72
1.00
C
563.8
363.5
247.5
1.64
0.91
0.49
0.73
1.15
D
717.4
479.8
326.6
2.07
1.20
0.63
0.87
1.44
E
1,076.1
719.7
490.0
3.11
1.81
0.96
1.30
2. 15
F
1,229.4
920.8
626.8
3.44
2.31
1.22
1.13
2.22
G
1,315.7
1,090.4
742.2
3.56
2.74
1.45
0.82
2. 11
H
3,947.0
3,271.2
2,226.8
10.68
8.21
4.32
2.47
6. 36
-------
4
10
16
gun cleanings per job
ounces of solvent used per gun cleaning
ounces per pound
As discussed in Chapter 2.0, there are two types of gun
cleaners, open (those that have no lid) and closed (those which
are closed while in service). The open cleaners have emissions
even when they are not being used because the solvent reservoir
is open to the atmosphere. Solvent may also be emitted from
closed gun cleaners if the lids do not seal tightly. When either
type of cleaner is in use, solvent can be emitted while the hose
connections are made to the gun. For purposes of this report,
emissions during the cleaning cycle are referred to as "active,"
and those during down time as "passive."
Emissions from gun cleaners were estimated with the
following equation:
age =
where:
EgC =
TJ
4
AL
percent
passive
8,760
PL
(TJ * 4 * AL) + (4-8)
(percent passive * 8,760 * PL)
annual emissions from a gun cleaner (lb/yr)
= total number of refinish jobs per year
« gun cleanings per job
* VOC emissions from active cycle (lb/cycle)
« fraction of time the gun cleaner is not in
use
= hours per year
* VOC emissions from passive losses (lb/hr)
tl».035
Drift NAPCTAC 11/91
-------
Typical emissions from gun cleaners have been reported as
0.059 lb/cycle for active losses and 0.00463 lb/hr for passive
losses.6 Table 4-7 summarizes the effect of gun cleaners on
emissions from each model shop.
4.3.2 Reduction of Volatile Organic Compound Emissions Due to
Use of Gun Cleaner
Emissions from shops that do not control solvent emissions
from cleaning spray guns can be reduced by the use of a gun
cleaner. The main reduction in solvent use is due to the fact
that (1) the cleaning solvent is reused many times until it
becomes too contaminated for further use, and (2) evaporative
losses are minimized. Solvent savings is estimated to be 60
percent for shops that install gun cleaners. Solvent savings
from the use of a gun cleaner is estimated by:
Efc * (l~Sre
-------
TABLE 4-7. GUN CLEANING EMISSIONS AND EMISSION REDUCTIONS
Model
shop
Gun Cleaning Solvent Usage
faal/vr)
Gun Cleaning Emissions
fton/vrt
Emission
reductions
(ton/yr)
Baseline
w/Gun cleaner
Baseline
w/Gun cleaner
A
55.8
22.3
0.20
0.02
0.18
B
124.3
49.7
0.45
0.05
0.40
Ca
71.9
71.9
0.08
0.08
None
D
265.4
106.2
0.97
0.11
0.86
Ea
143.8
143.8
0.16
0.16
None
F
342.5
137.0
1.25
0.14
1.11
Ga
184.9
184.9
0.19
0.19
None
Ha
184.9
184.9
0.19
0.19
None
-------
where:
EgC = emissions from a shop after installing a gun
cleaner (lb/yr)
Eb = emissions from same shop without a gun
cleaner (lb/yr)
Ere
-------
OCred ~ overall control (percent)
CEgfc = capture efficiency of the spray booth
(fraction)
CEao = control device efficiency (fraction)
Incineration can achieve 98 percent or greater destruction
efficiency.7 Biofiltration reportedly achieves 90 percent
destruction efficiency and carbon adsorption can achieve
95 percent or greater adsorption efficiency.9
Emissions from a shop with an add-on control device are
calculated by:
Eac = Etot * [(10° " °Cred)/100] (4-12)
where:
Eac ¦ emissions after installation of an add-on
control device (lb VOC/yr)
Etot = total annual emissions from coatings
(lb VOC/yr)
ocred " overall control (fraction)
Table 4-8 presents the emission reductions that can be achieved
with add-on controls for Shop H.
4.5 REDUCTION OF VOLATILE ORGANIC COMPOUND EMISSIONS WITH
IMPROVED HOUSEKEEPING PRACTICES
The emission reductions achievable through improved
housekeeping practices would vary significantly because of the
variability in present practices. Nonetheless, there are common
sense work practices that all shops can adopt to reduce
emissions. Workers should take care to minimize use of coatings
and solvents. Recycling or incineration of waste coatings and
solvents can reduce VOC emissions. The regulating agency can
require all shops to maintain a manifest of these wastes to
assure that they are delivered to a licensed waste
disposal/treatment facility. For on-site distillation units,
shop records should reflect efficient solvent recovery.
tls.033
Draft NAPCTAC 11/91
-------
TABLE 4-8. ADD-ON CONTROL EMISSION REDUCTIONS FOR MODEL SHOP H
Baseline
Emissions
fton/vr)a
Controlled
Emissions
(ton/yr)
Emission
Reduction
(ton/yr)
Catalytic
Incineration13
11. 37
0.57
10.80
Carbon
Adsorption0
11. 37
1.14
10.23
Biofiltrationd
11.37
1.14
10.23
^Emissions from coating applications and specialty products onlv
bEmission reduction for incineration - 95%; with heat recovery
cEmission reduction for carbon adsorption = 90%.
^Emission reduction for biofiltration » 90%.
-------
4.6 SUMMARY OF EMISSION ESTIMATION TECHNIQUES
This chapter presents the calculations used to estimate VOC
emissions from the automobile refinishing industry. The model
shops described in Chapter 2.0 are used to help estimate these
emissions. The emission reductions that can be achieved using
the control technologies described in Chapter 3.0 are also
quantified for each model shop. Both VOC emissions and emission
reductions are calculated based on estimates of surface area
covered by the coatings and surface preparation products used in
each model shop.
Waterborne surface preparation products have VOC levels
below 1.7 lb VOC/gal (200 g VOC/L) including water. When used on
an equal volume basis their use will effect a 73 percent
reduction in VOC emissions.
For each coating category (pretreatment wash primers and
precoats, primer surfacers, primer sealers, and topcoats) the
average volume percent solids was calculated from data provided
by the industry. This value was used to calculate the amount of
wet coating required to cover a given surface area. The total
area painted annually was used to obtain the amount of coating
used annually. That value, multiplied by the average VOC content
used for the baseline in each category yields annual emissions.
The same method was used to estimate the emissions for each
model shop were it to use coatings that comply with VOC limits of
Options l and 2. Potential emission reductions were then
obtained by difference. Model Shops A and B, whose baselines
presume the use of coatings with the highest VOC contents, would
cut coating emissions in half (55 percent) by switching to
Option 1 coatings. If they changed to Option 2 coatings the
reduction would be almost three quarters (70 percent). Model
Shops G and H, which are presumed to use coatings with the lowest
baseline VOC levels, would reduce emissions by a quarter
(23 percent) by converting to Option 1 coatings and by half
(48 percent) through substitution of Option 2 coatings.
Model shops which do not have gun cleaners (A, B, D, and F)
tU.035
Draft NAPCTAC 11/91
-------
would reduce emissions from cleaning spray guns by 88 percent
through use of an automated gun cleaner which recirculates
solvent and minimizes evaporative losses.
The use of add-on controls was evaluated only for Model
Shop H and the control would affect only VOC emitted during the
spraying operation. These emissions are assumed to be reduced by
95 percent through incineration, and 90 percent through carbon
adsorption and biofiltration.
tU.035
Draft NAPCTAC 11/91
-------
4.7 REFERENCES
1. Letter from Ocampo, G. P., The Sherwin-Williams
Company, to Ducey, E., U. S. Environmental Protection
Agency. October 30, 1990.
2. U.S. Environmental Protection Agency. Glossary for Air
Pollution Control of Industrial Coating Operations.
2nd Edition. Office of Air Quality Planning and
Standards, Research Triangle Park, North Carolina. EPA
Report No. 450/3-83-013R. 1983.
3. PPG Refinish Manual. PPG Industries. 1989.
4. Attachments provided by Bazil, K., The Sherwin-Williams
Company, to Floyd, w., Radian Corporation. December
11, 1990.
5. Bay Area Air Quality Management District. Staff Report
on Proposed Regulation 8, Rule 45—Motor Vehicle and
Mobile Equipment Coating Operations. May 1, 1989.
6. ENSR Consulting and Engineering. Comparison of solvent
Emissions from Two Types of Spray Gun Cleaning Systems.
Prepared for Safety-Kleen Corporation. ENSR Document
No. 5831-005800. March 1990.
7. Memorandum and attachments from Farmer, J. R., u. s.
Environmental Protection Agency. Thermal Incinerator
Performance for NSPS. August 22, 1980.
8. RMT Network. Air Pollution Control Costs May be
Reduced with Biotechnology: Biofiltration Provides
Environmentally Benign Solutions.
9. Radian Corporation. Economic, Energy, and
Environmental Impacts of Add-on VOC Controls on the
Automotive Refinishing Industry in New Jersey.
Prepared for the New Jersey Department of Environmental
Protection. August 1987.
tU.03S
Draft NAFCTAC 11/91
-------
5.0 IMPACT ANALYSIS OF ALTERNATIVE CONTROL TECHNOLOGIES
This chapter addresses the economic and environmental
impacts of the methods described in Chapter 3.0 for controlling
volatile organic compound (VOC) emissions from automobile
refinishing. Sections 5.1/ 5.2, 5.3, and 5.4 discuss the costs
of controlling VOC emissions from surface preparation, coating
applications (primers and topcoats), gun cleaning, and add-on
controls, respectively. Section 5.5 describes the potential
environmental impacts of the various control strategies. Details
of the costing methodology used to prepare these estimates are
shown in Appendix C.
5.1 COSTS OF CONTROLLING EMISSIONS FROM SURFACE PREPARATION
No capital costs are incurred by the body shop in switching
from conventional to lower VOC surface preparation products.
Operating costs are higher because lower VOC products are more
expensive than conventional products. The following equation was
used to calculate the costs of controlling VOC emissions from
surface preparation:
SPC - SP * (LOVOC - CONV) (5-1)
where:
SPC ¦ annual lower VOC surface preparation costs ($/yr)
SP * surface preparation usage (gal/yr)
LOVOC* lower VOC surface preparation price ($/gal)
CONV » conventional surface preparation price ($/gal)
Control costs are based on a price of $13.50 per gallon for
conventional surface preparation products and $18.50 per gallon
for lower VOC products.1 The same amount of lower VOC as
-------
conventional surface preparation products is reportedly needed to
prepare a surface for refinishing, therefore, the cost of control
is equal to the incremental per gallon cost of using lower voc
versus conventional products. Table 5-1 presents the surface
preparation costs for each model shop using conventional and
lower VOC surface preparation products based on the amount of
surface preparation product used by each model shop in the
baseline (see Chapter 4.0).
Table 5-1 also presents the incremental cost difference for
each model shop using lower VOC products. The cost increase
ranges from $26 per year for Model Shop A to $633 per year for
Model Shop H.
5.2 COSTS OF CONTROLLING EMISSIONS FROM COATING APPLICATIONS
Two options for VOC control from coating applications were
discussed in Chapter 3.0. Both options involve the use of
higher-solids or waterborne coatings. For Model Shops A, B, and
C, costs for control of VOC emissions include coating costs (over
baseline costs) and capital costs for installing a spray booth.
For the other model shops, only increased coating costs are
incurred because these shops already have a spray booth.
5.2.1 Coating Costs
To compare the costs of Option 1 and Option 2 coatings to
conventional coatings, the coating costs are calculated using an
estimated coating use per car (see Chapter 4.0) and coating cost
per gallon. Baseline coating costs are calculated for each
coating type (lacquer, enamel, or urethane) as shown below:
PCb - Pb * PPb (5-2)
where:
PCb « annual coating cost ($/yr)
Pb ¦ annual coating usage as applied (gal/yr)
PPb ¦ coating price as applied ($/gal)
Each coating type's usage and cost must be summed to calculate
total baseline coating costs. Costs for control of VOC emissions
-------
TABLE 5-1. SURFACE PREPARATION COSTS
Baseline Surface preparation Incremental cost of
surface costs3 using lower voc
preparation ($/yr) surface preparation
Model
shop
usage
(gai/yr)
Conventional
Lower VOC
products
($/yr)
A
5.3
71
97
26
B
9.0
122
167
45
C
14.1
190
260
70
D
»-¦
00
00
253
347
94
E
28. 1
380
520
141
F
35.6
481
659
178
G
42.2
570
780
211
H
126. 6
1,709
2,341
633
aUnit surface preparation product costs:
Conventional = $13.50/gal
Lower VOC » $18.50/gal
tLi.035
Chptr-S.CTG
-------
from coating applications are calculated similarly, using the
equation:
PCl0K » PLow * PPlow (5-3)
where:
PCl0M= annual Option l (or Option 2) coating cost ($/yr)
Plow = Option 1 (or Option 2) coating usage (gal/yr)
PPio- - Option 1 (or Option 2) coating price ($/gal)
The coating costs per gallon are shown in Table 5-2. These costs
are based on a survey of the major coating manufacturers for the
automotive refinish industry conducted by the U.S. Environmental
• 2
Protection Agency (EPA) in March of 1990. in order to compare
coating costs for the baseline, Option l, and Option 2 coatings,
the solids content must be taken into consideration. Coatings
cannot be compared on a gallon-to-gallon basis because as the
solids content increases, less coating can be applied to achieve
the desired film thickness. This is reflected in Table 4-3 where
coating use per car for baseline, Option 1, and Option 2 coatings
is shown. Costs are therefore compared on a coating solids basis
because the solids content determines the amount of coating that
must be applied.
Option 1 and 2 primer costs are assumed to be the same as
conventional primer costs on a per gallon solids basis. Topcoat
costs are assumed to increase by 10 percent on a per gallon
solids basis with each increasingly stringent VOC option. The
increased topcoat costs reflect the coating industry's research
and development costs which have been expended to develop lower
VOC coatings that achieve color match with conventional coatings.
The costs presented in Table 5-2 are used to calculate the annual
coating cost associated with Option 1 and 2 coatings for each
model shop.
5.2.2 Sprav Booth Costs
As discussed in Chapter 2.0, the use of a spray booth is
desirable when the lower VOC coatings associated with Options 1
til.033
Chptr-S.CTG
-------
££ TABLE 5-2. COATING COSTS
r* .
H o
i u
Ut Uk
Conventional coatings
($/qal as applied)3
Lacquer
Enamel
Urethane
Option l*3
($/gal as applied)
Option 2b
($/gal as applied)
Pretreatment Hash
Primer (Precoat)
27
27
27
44
61
Primer Surfacer
19
36
36
50
46
Primer Sealer
22
45
45
45
45
Topcoat
32
65
70
70
103
aAs applied means the coating includes the reducer and/or catalyst.
bCoating costs for Options 1 and 2 are based only on the solids content and do not
-------
and 2 are used. This is primarily due to their longer drying
times. Therefore, it is assumed that the model shops that do not
have spray booths (A, B, and C) will choose to install a semi-
downdraft spray booth, and will incur capital costs. Appendix c
presents the spray booth costing methodology in detail. Assuming
that Model Shops A, B, and C will choose to install a semi-
downdraft spray booth, total annual cost is calculated with the
equation:
TAC = ACC + MC + EC + NG + AF + G&A (5-4)
where:
TAC ¦ total annual cost ($/yr)
ACC = capital recovery costs ($/yr)
MC - maintenance cost ($/yr)
EC ¦ electricity cost ($/yr)
NG - natural gas cost ($/yr)
AF - air filter cost ($/yr)
G&A » general and administrative costs ($/yr)
The spray booth installed cost of $30,000 is annualized over
15 years at an interest rate of 10 percent using a capital
recovery factor (CRF) of 0.1315.3 Spray booth operation and
maintenance (O&M) costs include natural gas for heating the booth
air, electricity for the fan, air filters, maintenance costs, and
general and administrative (G&A) costs such as taxes and
insurance. The spray booth O&M costs increase from Model Shop A
to Model Shop C because each successive shop performs more
refinish jobs and thus uses its booth more. Maintenance costs
for a spray booth include replacement of light bulbs and
fixtures, natural gas burner maintenance, fan maintenance, and
booth cleaning and repainting. Maintenance costs and G&A costs
are each assumed to equal 4 percent of the capital costs/
5*2.3 Total Coating Costa
Table 5-3 shows the incremental coating costs for each model
shop for the Option 1 and 2 coatings, and shows the added capital
tla.03S
Chptr-S.CTG
-------
TABLE 5-3. SPRAY BOOTH AND COATING COSTS
£?
c
u
r»
m
Capital
Operating Costs
Increaental
Coating
Total Annual Costs
i
u
Capital
Capital
recovery
Maintenance
Natural
($/vr)
Costs Over
Baseline
Over
Baseline
O
Model
costs
recovery
cost
cost
gas
Other"
(t/vr)c
<$/vr>
•1
a
shop
(*»•
factor
(i/yr>
<*/yr>
(»)
Electricity Filters
<*>
Option 1
Option 2
Option 1
Option 2
A
30,000
0.1315
3,945
1,200
336
166 670
1,200
242
7U
7,760
8,231
B
30,000
0.1315
3,945
1,200
750
370 1,494
1,200
414
1,224
9,373
10,183
C
30,000
0.1315
3,945
1,200
1,087
536 2,163
1,200
338
1,603
10,469
11,734
D
0
0.1315
0
0
0
0 0
0
368
2,038
368
2,038
E
0
0.1315
0
0
0
0 0
0
553
3,OSS
553
3,058
f
0
0.1315
0
0
0
0 0
0
296
3,502
296
3.502
G
0
0.1315
0
0
0
0 0
0
0
3,749
0
3,749
H
0
0.1315
0
0
0
0 0
0
0
11,247
0
11,247
* Model shops without a spray booth (A, 8, and C) are assuaed to install a seai-downdraft booth.
b General and adftinistrative costs.
c VOC content as applied (lb VOC/gal coating, excluding water and exeapt solvents).
Pretreatnent
Wash Priner
(Precoat)
PriMer
Sur facer
Priaer
Sealer
Topcoat
Option 1
6.0
3.8
4.6
5.2
Option 2
5.5
2.1
4.6
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costs for a semi-downdraft spray booth for Model Shops A, B,
and C. Table 5-3 also shows the incremental coating and spray
booth costs over baseline coating costs. For Option 1,
incremental coating costs over baseline costs range from
approximately no coating costs over baseline for Model Shops G
and H to $553 per year for Model Shop E. For Option 2, coating
costs over baseline costs range from approximately $714 per year
for Model Shop A to $11,247 per year for Model Shop H. The range
in the incremental coating costs for the model shops reflects the
different VOC levels of the baseline coatings (which depends on
the types of baseline coatings used, i.e., lacquer, enamel, or
urethane) as well as the volume of coatings used. For example,
baseline coatings used by Model Shops G and H are similar to
Option 1 coatings in VOC content, and no incremental costs are
incurred. For Option 2 coatings, the VOC content is
significantly lower than the baseline coatings used by these
shops, and increased costs are incurred. Model Shop H has the
highest incremental coating costs for Option 2 ($11,247/year)
because it uses the highest volume of coatings* Total annual
costs of control are shown in Table 5-3. These costs include the
annual spray booth costs for Model Shops A, B, and C, and were
calculated as:
TPC - PCl0W - PCb + TAC (5-5)
where:
TPC « total incremental Option 1 or 2 coating cost
($/yr)
PCl0W « total annual Option 1 or 2 coating cost ($/yr)
PCb » total annual baseline coating cost ($/yr)
TAC - total annual spray booth cost ($/yr)
For Option 1, total annual cost over baseline cost ranges from no
increased annual cost for Model Shops 6 and H, to $10,469 per
year for Model Shop C. For Option 2, incremental total annual
tii.oas
Chptr-5.CTQ
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cost over baseline cost ranges from $2,038 per year for Model
Shop D to $11,734 per year for Model Shop C.
5.3 COST OF CONTROLLING EMISSIONS FROM GUN CLEANING
Emissions from gun cleaning can be reduced by using gun
cleaners that recirculate the cleaning solvent for several gun
cleanings (as discussed in Chapters 3.0 and 4.0). A cost savings
results from the reuse of cleaning solvent. Gun cleaner cost (of
$1,000 per gun cleaner) is annualized using an equipment life of
10 years and an interest rate of 10 percent.5 Total annual cost
for installing a gun cleaner is calculated with the equation:
TAC « ACC + MC - SS (5-6)
where:
TAC ¦ total annual gun cleaner cost ($/yr)
ACC - capital recovery cost ($/yr)
MC ¦ maintenance cost ($/yr)
SS ¦ solvent cost savings ($/yr)
Details are provided in Appendix C.
The maintenance cost includes replacement parts and
operating labor, and is assumed to equal 4 percent of the capital
costs. Table 5-4 presents the gun cleaner costs. Installing a
gun cleaner results in a cost savings for Model Shops B, D and F.
The net cost for Model Shop A is $36 per year.
5.4 COSTS OF CONTROLLING EMISSIONS WITH ADD-ON CONTROLS
An add-on control device is another method of controlling
VOC emissions from coating applications. To use an add-on
control device, a shop must have a spray booth so that emissions
can be contained for destruction or recovery. The costs
associated with add-on controls are calculated only for Model
Shop H. The costing methodologies for add-on controls are
provided in Appendix C.
5.4.1 catalytic Incineration Costa
The installed capital cost of a catalytic incinerator with
35 percent heat recovery on a spray booth exhaust stream of
tli.033
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TABLE 5-4. GUN CLEANER COSTS
Model
shop
Installed
capital
cost
<$)
Capital
recovery
factor
Annualized
capital
cost
($/yr>
Maintenance
cost
($/yr)
Solvent
savings
($)
Total
annual cost
($/yr)b
A
1,000
0.1627
163
40
167
36
B
1,000
0.1627
163
41
372
(170)
C
NAa
NA
NA
NA
NA
NA
D
1,000
0.1627
163
41
796
(592)
E
NA
NA
NA
NA
NA
NA
F
1,000
0.1627
163
42
1,027
(823)
G
NA
NA
NA
NA
NA
NA
H
NA
NA
NA
NA
NA
NA
aNot applicable (NA) since these shops already have a gun cleaner.
-------
12,000 acfm is estimated to be $443,000. *'8 The catallytic
incineration system with 35 percent heat recovery was found to be
the lowest cost alternative when compared to both direct thermal
incinerators and catalytic incinerators with no heat recovery and
higher rates of heat recovery (50% and 70%). Total annual cost
for catalytic incineration is calculated as follows:
TAC
ACC +ML+MM+EC+NG+ CAT + OL + SL + G&A
where:
(5
TAC
total annual cost for catalytic incineration
($/yr)
ACC
capital recovery cost ($/yr)
ML
maintenance labor costs ($/yr)
MM
maintenance material costs ($/yr)
EC
as
electricity cost ($/yr)
NG
M
natural gas cost ($/yr)
CAT
m
catalyst cost ($/yr)
OL
m
annual operating labor cost ($/yr)
SL
annual supervisory labor cost ($/yr)
G&A
*
general and administrative costs ($/yr)
Annual cost includes operating labor (including supervision),
maintenance labor and materials, natural gas for co-firing,
electricity for the fan, catalyst replacement, and general and
administrative costs.6 As shown in Table 5*5, the total annual
cost is $155,309 per year for Model Shop H.
5.4.2 ?,ftrP°n Adeorofclon
The installed capital cost of a carbon adsorber is estimated
to be $90,000.4,8 As outlined in Reference 4, the carbon adsorber
evaluated for this study does not regenerate spent carbon on
site. This arrangement avoids the need for steam, cooling water,
condensers, or elaborate controls.4 However, no credit is given
for recovered carbon. Total annual cost for carbon adsorption is
calculated as:
tl».033
Chptr-3.CTG
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TABLE 5-5. ADD-ON CONTROL COSTS FOR MODEL SHOP H
Catalytic
Incineration
Carbon
Adsorption
Capital cost ($) installed
443,000
90,000
Capital recovery factor
0.1627
0.1627
Annualized capital cost
($/vr)
72,076
14,643
Maintenance cost ($/yr)
3 , 500
3,500
Operating
costs
($/yr)
Natural gas
45,500
NA*
Electricity
3 ,500
6,020
Catalyst
11,000
NA
Carbon
NA
36,465
Operating labor
1,750
1, 750
0therb
17,983
3 ,863
Total annual cost ($/yr)
155,309
66,241
a Not applicable.
k General, supervisory, and administrative costs.
tU.035
Chptr-S.CTS
-------
TAC » ACC +ML+MM+EC+C+OL+SL+ G&A (5-8)
where:
TAC » total annual cost for carbon adsorption ($/yr)
ACC « capital recovery costs ($/yr)
ML » maintenance labor costs ($/yr)
MM = maintenance material costs ($/yr)
EC » electricity cost ($/yr)
C = annual carbon replacement cost ($/yr)
OL - annual operating labor cost ($/yr)
SL ¦ annual supervisory labor cost ($/yr)
G&A * general and administrative costs ($/yr)
Annual cost includes capital recovery, operating labor,
maintenance, electricity, carbon replacement, and G&A costs.6
Table 5-5 presents the total annual cost for carbon adsorption,
which is $66,244 per year for Model Shop H.
5.5 ENVIRONMENTAL IMPACTS OP CONTROLLING VOLATILE ORGANIC
COMPOUND EMISSIONS
The possible environmental impacts associated with applying
voc control technology to automobile refinishing operations
include effects on air quality, water quality, hazardous and
solid wastes, and energy consumption.
5.5.1 Air Quality Impacts
Emissions of air pollutants other than voc's are significant
for the add-on control options. The use of catalytic
incinerators nay result in the production of air pollutants
formed as a result of incomplete combustion. Possible by-
products resulting from voc combustion include nitrogen oxides,
carbon monoxide, sulfur dioxide, and particulate matter. The
most significant by-product for incineration is nitrogen oxide.
5.5.2 Water Quality
No adverse water pollution impacts are expected from any of
the voc control options.
tls.033
Chptr-S.CTG
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5.5.3 Hazardous Waste Impacts
Regenerated solvent from carbon adsorption is either
recycled or used as fuel. Thus, no hazardous waste impacts are
expected from any of the VOC control options.
5.5.4 Solid Waste Impacts
Solid waste impacts will be the largest environmental impact
for the model shops that are expected to purchase spray booths
(Model Shops A, B, and C). These shops will have an increase in
their solid waste generation as they replace their spray booth
filters. In general, spray booth filters must be replaced every
1-2 weeks, depending on the number of vehicles refinished.3
There will be a beneficial impact on solid waste generation by
all model shops, however, when Option l or Option 2 coatings are
used. The number of empty cans to be discarded will decrease
because the use of higher-solids coatings will allow the
refinisher to apply a thicker film with fewer coats for a
decrease in the amount of coating applied.
5.5.5 Energy Impacts
Energy impacts will be negligible with the use of gun
cleaners, which typically operate using compressed air. The
energy impacts (electricity and natural gas) associated with the
use of spray booths by Model Shops A, B, and C are shown in
Table 5-6. The emissions shown for nitrogen oxides (N0„), carbon
monoxide (CO), and hydrocarbons are associated with natural gas
use. The energy impacts associated with the use of catalytic
incineration and carbon adsorption for Model Shop H are shown in
Table 5-7. Except for disposal of spent carbon, electricity use
is the only impact associated with the use of carbon adsorption.
5.6 SUMMARY OF IMPACTS OF ALTERNATIVE CONTROL TECHNOLOGIES
This chapter discusses the costs involved in using low-VOC
surface preparation products, Option 1 and 2 coatings, gun
cleaners, and add-on controls (for Model Shop H only). Emissions
of air pollutants (other than VOC's), impacts on water quality,
hazardous wastes, solid wastes, and energy use are also
discussed.
ti.,035
Chptr-S.CTG
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TABLE 5-6. ENERGY IMPACTS OF SPRAY BOOTH USE
Energy
Usage
Emissions
Model
Electricity
shop
Natural gas
NO,
CO
Hydrocarbons
(kWh/yr)
(MMBtu/yr)
(lb/yr)
(lb/yr)
(lb/yr)
A
2,386
483
48
10
4
B
5,314
1,075
107
21
9
C
7,686
1,554
155
31
12
0
NAa
NA
NA
NA
NA
E
NA
NA
NA
NA
NA
F
NA
NA
NA
NA
NA
G
NA
NA
NA
NA
NA
H
NA
NA
NA
NA
NA
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If TABLE 5-7. ENERGY IMPACTS OF CATALYTIC INCINERATION AND CARBON ADSORPTION FOR MODEL SHOP H
«• •
H O
I U
Uk Ul
Catalytic
Incineration
Carbon Adsorption
Energy Usage
Emissions
Energy Usage
Hydro-
Electricity Natural gas
NOx CO
carbons
Electricity
(kWh/yr) (MMBtu/yr)
(lb/yr) (lb/yr)
(lb/yr)
(KWh/yr)
73,000 13,095 1,310 262 105 89,000
m
I
»-•
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In switching from conventional surface preparation products
to lower VOC products, the incremental costs per year for each
model shop range from $26 per year for Model Shop A up to
$63 3 per year for Model Shop H. The annual costs increase as the
amount of surface preparation product used increases.
When estimating the costs involved in switching from
baseline to Option 1 and Option 2 coatings, the cost of
installing a spray booth is first estimated for each model shop
that does not already have a booth. The coating costs are
estimated by combining the cost per gallon with the number of
gallons required to achieve the desired film thickness. The
total annual costs over baseline are the largest for Model Shops
A, B, and C because they incur the capital costs of installing a
spray booth. The largest costs for Option 1 are incurred by
Model Shop C ($l0,469/yr). No additional costs over baseline are
incurred for Model Shops G and H for Option 1 coatings. This is
because these shops already use coatings that have low VOC
levels. For the Option 2 coatings, Model Shops C and H incur the
highest annual costs ($ll,000/yr). This is because Model Shop c
has the added capital cost of a spray booth, and Model Shop H
uses a high volume of coatings (but does not have to buy a
booth). The lowest annual cost for Option 2 coatings is incurred
by Model Shop D ($2,000/yr), which already has a spray booth.
Installation of gun cleaners results in a cost savings for 3
of the 4 model shops because of the cost savings in gun cleaning
solvent. Model Shop A incurs annual costs of only $36.
Add-on control costs for catalytic incineration and carbon
adsorption for Model Shop H were estimated to be $143,000 and
$60,000 per year, respectively. For add-on controls to be cost
effective for the other model shops (that use spray booths less
frequently than the production shops), it may be possible for two
or more shops to co-own a spray booth equipped with an add-on
control device. Costs were not estimated for biofiltration
because this is a newly developed technology that is currently in
the test phase.
tis.oas
Chptr-S.CTO
-------
The air quality impacts associated with energy use for spray
booths and add-on controls were the only other impacts
quantified.
tl».033
Chptr-J.CTO
-------
5.7 REFERENCES
1. Telecon. Soderberg, E., Radian Corporation, Research
Triangle Park, NC, with Schultz, K., E.I. DuPont de Nemours
& Company, Inc., Wilmington, DE. February n, 1991.
2. Memorandum from Campbell, D.L., Radian Corporation, Research
Triangle Park, NC, to Ducey, E., U.S. Environmental
Protection Agency, Research Triangle Park, NC. Summary of
Coating Manufacturer's Survey Responses—Automobile
Refinishing CTG. February 28, 1991.
3. Telecon. Blackley, C.R., Radian Corporation, Research
Triangle Park, NC, with Preis, K., DeVilbiss, Smyrna, GA.
February 6, 1991.
4. Radian Corporation. Economic, Energy, and Environmental
Impacts of Add-on VOC Controls on the Automobile Refinishing
Industry in New Jersey. Prepared for the State of New
Jersey Department of Environmental Protection. August 1987.
5. Memorandum from Campbell, D.L., Radian Corporation, Research
Triangle Park, NC, to Ducey, E., U.S. Environmental
Protection Agency, Research Triangle Park, NC. Solvent
Recovery System Manufacturers Survey Summary—'Automobile
refinishing CTG. September 3, 1990.
6. U.S. Environmental Protection Agency. OAQPS Control Cost
Manual. Office of Air Quality Planning and Standards.
Research Triangle Park, NC. EPA-450/3-90-006.
January 1990.
tls.035
Chptr-J.CTG
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7. Attachments to letter from Ocampo, G.P., The Sherwin-
Williams Company, Cleveland, OH, to Ducey, E., U.S.
Environmental Protection Agency, Research Triangle Park, NC.
October 30, 1990.
ti».03S
Chptr-S.CTO
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6.0 FACTORS TO CONSIDER WHEN IMPLEMENTING REASONABLY
AVAILABLE CONTROL TECHNOLOGY
6.1 INTRODUCTION
This chapter presents information on factors air quality
management agencies should consider in developing an enforceable
rule for limiting volatile organic compound (VOC) emissions from
automobile refinishing facilities. Information is provided on
important definitions, rule applicability, equipment and
operational standards, performance testing, and recordkeeping.
Where several options exist for implementing a certain aspect of
the rule, each option is discussed along with its advantages and
disadvantages in relation to the other options. In some cases,
there may be equally valid options. The State or other
implementing agency can exercise its prerogative to select other
options, provided that they meet the objectives prescribed in
this chapter.
This guidance is for instructional purposes only, and, as
such, is not binding. Appendix D contains an example of a rule
that includes the guidance provided in this document. The
example rule provides an organizational framework and sample
regulatory language specifically tailored for automobile
refinishing operations. The state or other implementing agency
should consider all information presented in this document, along
with additional information about the specific sources to which
the rule will apply. The final rule, however, should address all
the factors listed in this chapter to ensure that the rule is
enforceable and contains adequate provisions for demonstrating
compliance.
-------
6 .2 uEFIIvITIOHS
In order to be useful and clear, the rule should accurately
describe the types of sources that would be affected, and clearly
define the terms used to describe the industry and applicable
control methods. This section offers guidance to agencies in
selecting terms that may need to be clarified when used in a
regulatory context. Example definitions have been compiled from
industry and U.S. Environmental Protection Agency (EPA) sources.
Add-on control device. An air pollution control device such as a
carbon adsorber or incinerator which reduces the pollution in an
exhaust gas. The control device usually does not affect the
process being controlled and thus is "add-on" technology as
opposed to a scheme to control pollution through making some
alteration to the basic process.
Adhesion promoter. A coating used to promote adhesion of a
topcoat on surfaces such as trim moldings, door locks, and door
sills, where sanding is impracticable.
Aftermarket automobiles. Vehicles that have been purchased from
the original equipment manufacturer.
Anti-alare safety coating. A low gloss coating formulated to
eliminate glare for safety purposes on interior surfaces of a
vehicle, as specified under the U.S. Department of Transportation
Motor Vehicle Safety Standards.
"As applied." The condition of a coating after dilution by the
user just prior to application to the substrate.
coating. A protective or decorative film applied in a thin layer
to a surface. This term often applies to paints such as lacquers
or enamels, but also is used to refer to films applied to paper,
plastics or foil.
Coating "system." Today's automobile refinishing products are
marketed as a primer-topcoat package or system. The coating
manufacturer provides a warranty for products only when they are
used in the suggested combinations.
Elastomerlc materials. Topcoats and primers that are
specifically formulated for application over flexible parts such
-------
as fiilar ysmssla and elastomeric bumpers.
Gun cleaner. A device made specifically to clean paint from
spray guns which recirculates solvent to clean a succession of
times, and is vapor tight when in use.
Light- and medium-duty trucks. Any truck or van having a
manufacturer's gross vehicle weight rating of 10/000 pounds or
less.
OEM. Original equipment manufacturer.
Overall control. The product of the capture efficiency and the
control device efficiency gives an overall control efficiency.
Overspray. That solids portion of a coating sprayed from an
applicator which faiis to adhere to the part being sprayed.
(Applied solids plus overspray solids equal total solids
delivered by the spray application system.)
Primer. Any coating applied prior to the application of a
topcoat for the purpose of corrosion resistance, adhesion of the
topcoat, and color uniformity.
Precoat. The first coat applied to bare metal primarily to
deactivate the metal surface for corrosion resistance to a
subsequent waterborne primer.
Pretreatment wash primer. The first coat applied to bare metal
if solventborne primers will be applied. This coating contains a
minimum of 0.5 percent acid by weight, is necessary to provide
surface etching, and is applied directly to bare metal surfaces
to provide corrosion resistance and to promote adhesion.
Primer sealer. An undercoat that improves the adhesion of the
topcoat, provides corrosion resistance, and promotes color
uniformity.
Primer surfacer. A coating which gives "body" to the surface,
fills in irregularities, and is intentionally thick enough to
permit sanding without cutting through to bare metal.
RACT. Reasonably available control technology. Defined as the
lowest emission limitation that a particular source is capable of
meeting by application of control technology that is reasonably
available considering technological and economic feasibility.
-------
specialty am; additives. Coatings or additives that are
reportedly necessary due to unusual job performance requirements.
These coatings or additives prevent the occurrence of surface
defects and they impart or improve desirable properties. These
products include uniform finish blenders, elastomeric materials
for coating flexible plastic parts, gloss flatteners, and anti-
glare/safety coatings.
Surface preparation products. Products used to remove wax, tar,
grease, and silicone from the surface to be refinished.
Topcoat . The last coat applied in a coating system. Topcoats
can be single-stage,, basecoat/clearcoat, or basecoat/
midcoat/clearcoat.
Transfer efficiency. The ratio of the amount of coating solids
deposited onto the surface of the coated part to the total amount
of coating solids used.
Uniform finish blender. A thinner or low solids clear solution
which is used to melt overspray from a repaired area into the
unrepaired color.
6.3 APPLICABILITY
This Control Techniques Guideline (CTG) applies to auto body
repair and paint shops which do the majority of the automobile
refinishing work; production paint shops; new car dealers' repair
and paint shops; and fleet operators' repair and paint shops.
This CTG is intended to provide guidance for regulating the
refinishing of aftermarket automobiles, vans, motorcycles, and
light- and medium-duty trucks. Aftermarket, in this usage, is
defined as equipment that has been purchased from the original
equipment manufacturer, and includes those vehicles at the
retailer that may be on consignment. It includes repairing
imported cars on the dock, and dealers' repairs made on vehicles
damaged in transit. Finally, the specific processes to which
this CTG applies are surface preparation, coating application,
and spray gun cleaning.
This CTG does not provide guidance for regulating th6
refinishing of other types of mobile equipment, such as farm
-------
machineiij, unci construction equipment, which are discussed in the
CTG entitled "Control of Volatile Organic Emissions from Existing
stationary Sources—Volume VI: Surface Coating of Miscellaneous
Metal Parts and Products" (EPA-450/2-78-015, June 1978).
6.4 FORMAT OF STANDARDS
The control techniques included in this guidance document
are the following: (1) reducing the VOC content of the products
used for preparing the surface to be refinished, (2) reducing the
VOC content of the coatings used, (3) modifying the gun cleaning
process, (4) implementing add-on controls to existing refinishing
facilities, and (5) improved housekeeping practices. Chapter 3
contains a detailed discussion of these techniques.
Two formats are appropriate for regulations covering the
automobile refinishing industry. These are operational
standards, and equipment standards. The following subsections
present detailed discussions of each of these as it applies to
the refinishing of automobiles. A subsection addressing add-on
controls is also included.
6.4.1 Operational fProcass and Material Change! standard
Operational standards apply to practices that, when
implemented in a process or procedure, decrease the potential for
emissions to occur. Requiring a change to a product with a lower
VOC content is considered an operational standard. [VOC limits
should be expressed in terms of grams of VOC per liter of
product, and pounds of VOC per gallon of product, less water, as
applied, to ensure a common basis for the comparison of different
products. In the event a coating contains or releases a
negligibly photochemically reactive compound, these should be
treated as inert materials (just like water) in all VOC
calculations.] Section 3.3 contains a detailed discussion of how
to achieve emission reductions from coating applications.
Chapter 4 contains equations to use for calculating emissions
from solventborne (eq. 4-6) and waterborne (eq. 4-7) coatings.
Two options for standards for the refinishing industry have
been presented. These were developed based on a 1990 EPA survey
-------
of the sjor manufacturers of automobile refinishing coatings.1
Based on the survey results, coatings which meet the Option 1 VOC
limit can be combined into many coating systems that are expected
to be able to match all OEM colors. Coatings which meet the
Option 2 limit have lower VOC levels than Option 1 coatings, are
currently available, and are expected to achieve color match.
However, they cannot be combined for use in as many coating
systems as Option 1 coatings.
In addition, good housekeeping practices can reduce VOC
emissions. These are difficult to enforce but should be
encouraged by the regulating agency.
6.4.2 Equipment Standard
Equipment standards address the kinds of equipment which can
be used to reduce VOC emissions. The use of spray equipment with
improved transfer efficiency can significantly reduce VOC
emissions by decreasing overspray and the attendant emissions
from overspray (see Section 2.5). However, the transfer
efficiency of spray equipment is greatly dependent upon many
factors which include not only the equipment but the skill of the
operator, the shape and size of the surface being coated, the
distance the spray nozzle is held from the surface, and the
coating being applied.
The requirement that facilities use gun cleaners is a more
practical and enforceable equipment standard. Properly used, a
gun cleaner will significantly reduce VOC emissions from the gun
cleaning process. At the same time, it reduces the amount of
solvent which a shop must purchase, and provides a more healthful
environment for the worker because of reduced exposure to VOC's.
6.4.3 Add-on Control Devices
Add-on controls can be used to achieve VOC reductions. For
the automobile refinishing industry, an add-on control device can
be used to remove VOC from the solvent-laden spray booth exhaust.
Drawbacks to the use of add-on controls such as incineration or
carbon adsorption relate to the low VOC concentration of the
booth exhaust (I00ppm-1500ppm), and the infrequency of the spray
-------
painting which is ciorie in a typical shop. For this situation,
the operating costs are very high. An option might be to require
shops to complete their refinishing in a facility owned by
multiple shops, which is dedicated to the spray painting
operation. This would make the capital and operating costs for
the add-on control more affordable. Biofiltration, on the other
hand, is well suited to control airstreams with the low VOC
concentrations typical of the exhaust from refinishing spray
booths. Biofiltration is relatively new to the air pollution
control community, but it is expected it will offer distinct
advantages over other technologies for the control of streams
which contain readily biodegradable pollutants in low
concentrations.
6.5 OPERATIONAL STANDARDS
6.5.1 Surface Preparation Products
A process or material change which might be imposed on the
use of surface preparation products could be based on waterborne
formulations in which the active ingredient is detergent rather
than solvent. Conventional solventborne surface preparation
products have an average VOC content of 6.4 pounds of VOC per
gallon (lb VOC/gal) (767 g VOC/£). The recommended limitation
for these products is 1.7 lb VOC/gal (200 g VOC/£) including
water. These products function because of their ability to wet
the substrate and remove any surface contamination. Since equal
volumes of solventborne or waterborne product are used, and there
are no coating solids to take into consideration, the water is
included in the VOC content which is reported.
6.5.2 primer Category
The primer category is comprised of pretreatment wash
primers, precoats, primer surfacers, and primer sealers. For
each of these products a recommended VOC level is given for both
Options l and 2.
Pretreatment wash t>rim«rs Pretreatment wash primers
typically have VOC levels of around 6.5 lb VOC/gal (708 g V0C/£)
less water, as applied. Under Option 1, the recommended
-------
limitation is 6 0 lb VCC/CjL.. . .0 ""• ¦'•/<•, less water as
applied. Under Option 2, 5.5 lb VOC/gal (420 g VOC/£) less
water, as applied is recommended.
Precoats. Precoats typically have VOC levels of around 6.5
lb VOC/gal (708 g VOC/£) less water, as applied. Under Option 1,
the recommended limitation is 6.0 lb VOC/gal (720 g VOC/£) less
water, as applied. Under Option 2, 5.5 lb VOC/gal (420 g V0C/£)
less water, as applied is recommended.
Primer surfacers. Primer surfacers have VOC levels which
typically range between 4.8 and 5.7 lb VOC/gal (580 to 680 g
VOC/I) less water, as applied. Under Option 1, 3.8 lb VOC/gal
(460 g VOC/£) less water, as applied is the recommended limit.
Under Option 2, 2.1 lb VOC/gal (250 g VOC/£) less water, as
applied is recommended. Currently available primer surfacers
that meet the Option 2 limit are waterborne.
Primer sealers. Typical primer sealer VOC levels range from
4.6 to 5.6 lb VOC/gal (550 to 670 g VOC/£) less water, as
applied. The recommended limitation under either option for
primer sealers is 4.6 lb VOC/gal (550 g V0C/£) less water, as
applied.
6.5.3 Topcoats
As discussed in Chapters 2 and 3 of this CTG, topcoats can
be single-stage, two-stage (basecoat and clearcoat), or three-
stage (basecoat, midcoat, clearcoat). If the equations
presented in Section 3.3 are applied, the average VOC content
ranges from 5.2 to 6.0 lb VOC/gal (620 to 720 g VOC/£) less
water, as applied.
Option 1 recommends 5.2 lb VOC/gal (620 g VOC/fc) less water,
as applied. Option 2 limits topcoats to 4.5 lb VOC/gal (460 g
VOC/I) less water, as applied.
6.5.4 Additives and Specialty Coatings
Because additives and specialty coatings reporteidly are
required for unusual performance requirements, used only in small
amounts, result in a more durable finish, and allow better color-
matching, their VOC content should be limited to 7.0 lb VOC/gal
-------
(840 g VOC/l) less water, as In conjunction with this
VOC limit, it is recommended that State regulations limit the use
of these additives and coatings to a maximum of 5 percent of the
volume of all coatings applied in a shop on a daily basis.
6.5.5 improved Housekeeping Practices
Emission of VOC's from refinishing facilities can be
decreased through improvements in the practices of storing and
disposing of materials. Fresh and spent solvent should be stored
in safety containers with gasket sealed, spring loaded covers
such as those listed and registered by Underwriters Laboratories.
The amount of time during which covers or lids of containers are
open should be minimized. A second conservation technique which
is not as simple to enforce is for personnel to keep solvents
used for cleaning to a minimum.
Paint use can be reduced by mixing only the amount required
to complete a refinishing job. waste paint, spent solvent, and
sludge from gun cleaners or in-house distillation units should be
properly disposed of either through a licensed reclaiming
facility or a designated hazardous waste management facility.
States can include in their regulations a provision that
inspectors who find unattended open containers of solvent will be
cited, and that proper documentation will be required to verify
that spent solvents are being disposed of through accredited
facilities.
6.6 EQUIPMENT STANDARDS
6.6.1 Spray Equipment
The benefits of high transfer efficiency are discussed
because of its potential cost and VOC emission reduction. Due to
the myriad of variables that affect transfer efficiency, the EPA
has not found a reliable, reproducible method for measuring it
except under the most ideal circumstances. For that reason,
there is no recommendation for incorporating it into a State
regulation. A number of studies indicate that under identical
test conditions, those spray systems which use greater pressure
to apply the coating tend to deliver the coating to the substrate
6-9
-------
less efficiently. This: data should be approp.riatr for the
automobile refinishing industry, but may be an oversimplification
in other industries. The potential benefits for this industry
appear sufficient to warrant encouraging the use of low pressure
spray equipment.
State regulations should encourage facilities to consider
the impact of improvements in the transfer efficiency of spray
equipment, both for the economic benefit to their business and
from the standpoint of reducing VOC emissions.
6.6.2 Gun Cleaners
It is suggested, that States approve only those gun cleaners
that:
(1) Recirculate the solvent used during the cleaning
process so that the solvent is used to clean a
number of guns before being disposed.
(2) Collect the spent solvent in a manner that ensures
it is available for disposal.
(3) Are vapor tight during the cleaning process
(4) Meet applicable fire safety and occupational
safety and health codes, laws, and regulations
both in design and in the manner in which it can
be used.
State regulations should specify that the facility is accountable
for spent solvent from the gun cleaner. It must not be allowed
to evaporate. Documentation must be available to support that it
has been released to a licensed reclaiming or hazardous waste
management facility.
6.7 ADD-ON CONTROL DEVICES
A State should consider including a statement within the
regulation which allows a facility to use an add-on control
device in lieu of lower VOC coatings. The add-on control device
must achieve an overall control which is equivalent or greater
than the emission reduction levels achieved by the use of lower
VOC coatings.
6.8 REPORTING AND RECORDKEEPING
Each facility affected by the State regulation should keep
records of key parameters that indicate compliance. The model
-------
rule in Appendix D c ntains an of tr.h J!;inds of
recordkeeping that the regulating agency could consider
requiring. The facility should identify the control methods or
equipment standard selected to meet the rule requirements. The
results of any performance and equipment standard testing should
be recorded. For the refinishing industry, this might apply to
in-house distillation units or gun cleaners. The facility should
record all of the parameters monitored on a routine basis to
indicate continued compliance. The record should note any time
the monitored parameters are exceeded, and the corrective action
taken. The regulating agency should decide which data need to be
maintained (or reported) and if reporting is required, the
frequency. Some suggested recordkeeping and reporting procedures
for operational standards and equipment standards are discussed
below.
6.8.1 np<>-r«tiional Standards
Records should be kept to demonstrate that the coatings used
(as applied) comply with VOC content limits for each regulated
category of coating. Records should be kept for each job
performed which specify the following information: (1) the volume
and VOC content (including water) of any surface preparation
product used, (2) the volume of coating, catalyst, and reducer
used, the mix ratio of components used, and the VOC content of
the coating, less water, as applied, and (3) the volume and VOC
content (less water, as applied) of each specialty coating and
additive used.
6.8.2 Rgulpmant Standards
For gun cleaners, records of routine maintenance and repairs
will ensure the proper performance of the equipment. In the case
of gun cleaners, volume and frequency of replacement solvent
added, and number of guns cleaned should be recorded. Shop
owners should also be able to demonstrate or certify that the
spent solvent from gun cleaners is being disposed of through
licensed facilities (landfill disposal of those solvents
typically used by the industry has been banned). All spent
-------
solvents used in the industry ar>*. Resource Cons ar^rtion Recovery
Act (RCRA) regulated hazardous wastes, and shops are required to
maintain documentation of their handling and disposal. Many
States require that waste manifests and annual or biennial waste
reports include the method of disposal. In those states where
this RCRA-driven documentation is not required, shop owners could
demonstrate compliance by requesting and retaining documentation
of the disposal method from their contracted disposal firm.
6.8.3 Add-on Control Devices
If add-on control devices are installed, performance records
of these control devices should be maintained. The overall
emission reduction efficiency for a period of time (day, week, or
month) can be determined. Logs of operating times, and
maintenance logs (including dates and durations of outages) are
all necessary records to show compliance. Noncompliance for
control devices should be reported within 30 days of the
noncompliance. Performance test results should be maintained on
site, and periodic retests may be required.
-------
6.8 REFERENCES
1. Memorandum from Campbell, D.L., Radian Corporation, Research
Triangle Park, NC, to Ducey, E., U.S. Environmental
Protection Agency, Research Triangle Park, NC. Summary of
Coating Manufacturer's Survey Responses—Automobile
Refinishing CTG. February 28, 1991.
-------
APPENDIX A
-------
APPENDIX A
CONTACTS
The following is a list of suppliers, equipment vendors,
trade organizations, and government representatives that may
provide additional information on issues concerning automotive
refinishing.
A.l COATING SUPPLIERS
Inglis, Mr. Robert
Director, New Product Coordination
BASF Chemicals
19855 W. Outer Drive, Suite 401 East
Dearborne, Michigan 48124
McConachie, Mr. William
Technical Manager
The O'Brien Corporation
450 East Grand Avenue
South San Francisco, California 94080
Ocampo, Mr. Gregory
Product Manager
The Sherwin-Williams Company
101 Prospect Avenue, N.W.
Cleveland, Ohio 44115-1075
Rosenberg, Mr. David
Director of Marketing
Composition Materials Co., inc.
1375 Kings Highway East
Fairfield, Connecticut 06430
tl$.027
-------
Rumer, Mr. Roger
Coatings Division
Mobay Corporation
Mobay Road
Pittsburgh, Pennsylvania 15205-9741
Schultz, Mr. Karl
Environmental Consultant - Automotive Products
E.I. DuPont de Nemours & Company
1007 Market Street
Wilmington, Delaware 19898
Sieradzki, Mr. Raymond
Laboratory Director, Car Refinishes
Akzo Coatings, Inc.
Post Office Box 7062
Troy, Michigan 48007-7062
A.2 SPRAY EQUIPMENT VENDORS
Butcher, Mr. Robert
National Sales Manager
AccuSpray Inc.
26881 Cannon Road
Post Office Box 391525
Cleveland, Ohio 44139-1525
Bunnell, Mr. Michael
President/C.E.O.
Can-Am Engineered Products, Inc.
30850 Industrial Road
Livonia, Michigan 48150
tla.027
-------
Flores, Nr. James
District Manager
Graco Inc.
7158 Open Hearth Drive
Kernersville, North Carolina 27284
Lowe, Mr. Ronnie
Air Power, Inc.
2304 Atlantic Avenue
Post Office Box 41165
Raleigh, North Carolina 27629-1165
Lumby, Mr. Mick
Vice President
Croix Air Products, Inc.
520 Airport Road
Fleming Field
South St. Paul, Minnesota 55075
Mazzotta, Mr. John
Vice President
Sharpe Manufacturing Co.
1224 Wall Street
Los Angeles, California 90015
Preis, Mr. Kenneth
DeVilbiss Automotive Refinishing Products
3200 Highlands Parkway, Suite 304
Smyrna, Georgia 30082
West, Mr. Thayer
UNICARb" Department
Union Carbide Chemicals and Plastics Company, Inc.
39 Old Ridgebury Road
Danbury, Connecticut 06817-0001
tts.027
-------
Williams, Mr. John
AIMCO
Post Office Box 80153
Conyers, Georgia 30208
A.3 SPRAY BOOTH MANUFACTURERS
Elder, Ms. Cindy
Auto Equipment Co., Inc.
Post Office Box 88442
Atlanta, Georgia 303 56
Preis, Mr. Kenneth
DeVilbiss Automotive Refinishing Products
3200 Highlands Parkway, Suite 304
Smyrna, Georgia 30082
A.4 GUN CLEANING EQUIPMENT MANUFACTURERS AND SOLVENT RECOVERY
CONTACTS
Johnston, Mr. Charles
Regional Sales Manager
Lenan Corporation
615 North Parker Road
Jamesville, Wisconsin 53545
Kusz, Mr. John
Manager, Product Development
Safety-Kleen Corporation
777 Big Timber Road
Elgin, Illinois 60123
Lighthall, Mr. Scott and Ms. Krista
Lighthall Industries
611 Cedar Street
Post Office Box 1356
-------
Marchitelli, Mr. Richard
President
PBR Industries
4 00 Farmington Road
ast Babylon, New York 11704
Robb, Mr. Richard
President
Herkules Equipment Corporation
8230 Goldie Street
Walled Lake, Michigan 48088-1298
A.5 TRADE ORGANIZATIONS
Greenhaus, Mr. Douglas
Senior Attorney, Regulatory Affairs
National Automobile Dealers Association
8400 Westpark Drive
McLean, Virginia 22102
Randall, Mr. Donald
Washington Attorney
Automotive Service Association
321 D Street, N.E.
Washington, D.C. 20002
Sell, Mr. James
Senior Counsel, State Affairs
Secretary to the Automotive Refinish Coalition
National Paint and Coatings Association
1500 Rhode Island Avenue, n.w.
Washington, D.C. 20005-5597
tts.027
-------
Shearer, Mr. Scott
Automotive Service Industry Association
Suite 1405
1725 K Street, N.W.
Washington, D.c. 20006
St. Aubin, Ms. Barbara
Paint, Body, Equipment Association.
9140 Ward Parkway
Kansas City, Missouri 64114
A.6 GOVERNMENT REPRESENTATIVES
Baier, Mr. Russell
Mobile Source Section Chief
Texas Air Control Board
12124 Park 35 Circle
Austin, Texas 78753
Oalton, Ms. Kathy
New York Division of Air Quality
50 Wolf Road
Albany, New York 12233
Dvorak, Ms. Vicki
Enforcement Specialist
Bay Area Air Quality Management District
939 Ellis Street
San Francisco, California 94109
Kemker, Ms. Carol
U.S. Environmental Protection Agency
Region IV
345 Courtland Street, N.E.
Atlanta, Georgia 30365
tt(.027
-------
Latif, Mr. Abid
South Coast Air Quality Management District
9150 Flair Drive
El Monte, California 91731
Reddy, Ms. Beth
Division of Environmental Quality
New Jersey Department of Environmental Protection
CN-027
Trenton, New Jersey 08625-0027
Wong, Mr. Ed
Associate Air Resources Specialist
California Air Resources Board
Post Office Box 2815
Sacramento, California 95812
tit.027
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APPENDIX B
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APPENDIX B
EMISSION ESTIMATION
Sample calculations for the emission estimation techniques
used in Chapter 4.0 are shown in Sections B-1.0 through B-5.0.
The following sections describe step-by-step calculations for
determining product use and emissions for one of the model
shops (A), as an example. Calculations for the other model shops
are similar to the calculations shown here for Model Shop A.
B-1.0 ESTIMATION OF SURFACE PREPARATION PRODUCT USE BY MODEL
SHOPS
B-l.l Surface Area Estimation
The surface area refinished by Model Shop A is calculated by
assuming that for each full refinish job, 100 ft2 of surface is
prepared. For each partial job, an average of 10 ft2 of surface
is prepared. The total surface area coated per year is:
A - (FJ * 100) + (PJ * 10) (B-l)
where:
A » surface area coated per year (ft2/yr)
FJ ¦ full jobs completed per year
100 ® area coated per full job (ft2/full job)
Pj » partial jobs completed per year
10 « area coated per partial job (ft2/partial job)
Model Shop A refinishes 13 full vehicles and 150 partial vehicles
each year. For Model Shop A:
A « (13 full jobs/yr * 100 ft2/full job) + (150
partial jobs/yr * 10 ft2/partial job)
2,800 ft2/yr
-------
B-1.2 Surface Preparation Product Volume Used
For each full refinish job, 1.5 pints of surface preparation
product are required. For each partial refinish job, 0.15 pints
are required. The total volume of surface preparation product
each year is:
SP A * 0.015/8 (B-2)
where:
SP = annual surface preparation product usage (gal/yr)
A - total automobile surface area prepared per year
(ft /yr)
0.015 » pints of surface preparation used per square foot
8 - pints per gallon
For Model Shop A:
SP - 2,800 ft2/yr * 0.015 pints/ft2/(8 pints/gal)
» 5.3 gal/yr
Table 4-1 (Chapter 4.0) shows the estimated surface preparation
usage for the eight model shops.
B-2.0 ESTIMATION OF COATING USE BY MODEL SHOPS
Coating use by each model shop varies with the number of
refinish jobs completed each year and with the solids contents of
the coatings used. As the solids content increases, less coatinr
can be applied to achieve the desired film thickness. The
following sections describe the step-by-step calculations for
determining coating volume used by the model shops.
b-2.i surface Area Estimation
The surface area estimation for coating applications is
identical to the surface area estimation presented above for
surface preparation products. Thus, for Model Shop A, 2800 ft2
of surface is refinished each year.
-------
B-2.2 Coating Volume Used
Listed below are the average VOC contents (as applied, less
water and exempt compounds) of the lacquer, enamel, and urethane
coatings for each type of refinish product:
vne content as Applied fib VOC/aal coating!
L4
-------
(1 - 6.0 lb/gal/(7.3 lb/gal)) * 100
17.8 percent
The solids content calculated above is for lacquer primer
surfacers. solids content for enamel primer surfacers (at
4.8 lb VOC/gal coating) is 34 percent. The weighted average
primer surfacer solids content for Model Shop A, which uses
75 percent lacquers and 25 percent enamels, is 22 percent as
shown in Table 4-2 (Chapter 4.0).
The baseline coating use is calculated by combining the
percent of surface area coated with that type coating (lacquer,
enamel, or urethane), the total surface area refinished each
year, the solids content of the coating, the desired film
thickness, and the assumed transfer efficiency of the spray
equipment. The equation is shown below:
C « [Sa * A * t]/[1604 * Vs * TE] (B-4)
where:
C - annual coating usage (gal/yr)
Sa « fraction of surface area coated covered by
evaluated coating
A - surface area coated per year (ft2/yr)
t * dry coating film thickness (mils)
1,604 - area that 1 gallon of coating solids can cover to
1 mil thickness (ft * mil/gal)
Vs - volume solids content of coating (fraction)
TE ¦ transfer efficiency (fraction)
For primer surfacers, the desired film thickness (as shown
in Chapter 4.0) is 2.25 mils. The transfer efficiency of the
spray equipment is assumed to be 35 percent, and Model Shop A
-------
uses lacquer coatings on 75 percent of the refinished vehicles,
enamel coatings on 25 percent, and does not use urethane coatings
for any refinish jobs. For lacquer primer surfacers in Model
Shop A:
c = 0.75 * 2800 ftz/yr/[(1604 ft2 * mil/gal) *
17.8/100/2.25 mils * 0.35]
a 47.3 gallons lacquer primer surfacer/yr
Enamel coating usage for Model Shop A is estimated to be
8.2 gallons per year, using the above equations. Thus, total
primer surfacer usage for Model Shop A is 55.5 gal/yr, as shown
in Table 4-2 (Chapter 4.0). Coating use for pretreatment wash
primers, primer sealers, and topcoats is calculated as shown
above for primer surfacers.
B-3.0 ESTIMATION OF GUN CLEANING SOLVENT USE BY MODEL SHOPS
Gun cleaning solvent use is calculated by first determining
the number of times a spray gun will be cleaned by a shop. For
each full and partial refinish job, it is estimated that a spray
gun will be cleaned an average of four times as the painter
changes from one type of coating to another. The amount of
solvent used for each cleaning depends on whether or not the shop
has a gun cleaner that recirculates the cleaning solvent for
several cleanings. Thus, solvent use for gun cleaning is
discussed separately below, first for shops that clean their
spray gun without a gun cleaner, then for shops that have gun
cleaners.
B-3.1 solvtnt Use for Shoos Without Gun Cleaners
Model Shop A is used as an example for calculating the
amount of gun cleaning solvent that will be used each year for a
shop without a gun cleaner. For a shop without a gun cleaner,
the annual solvent usage for gun cleaning (which is equal to the
emissions because all the solvent is assumed to evaporate) is
calculated by:
-------
TJ * 4 * 10/16
(B-5)
where:
Eb ¦ solvent used for gun cleaning by a shop
without a gun cleaner (lb/yr)
TJ = total number of refinish jobs per year
4 * cleanings per job
10 » ounces of solvent used per gun cleaning
16 * ounces per pound
For Model Shop A:
Efc ® 163 jobs/yr * 4 cleanings/job *
10 oz./cleaning/(16 oz./lb)
* 407.5 lbs solvent used for gun cleaning/yr
(0.20 ton/yr)
Table 4*7 (Chapter 4.0) shows the gun cleaning solvent usage for
the eight model shops in gallons per year. [Note: 407.5 lbs
solvent/(7.3 lb/gal solvent) ¦ 55.8 gallons.]
B-3.2 Solvent Vgg C
-------
Sgc - Eb * (1- Sred) (B-6)
where:
SgC » annual solvent usage for gun cleaning by a shop
with a gun cleaner (lb/yr)
Eb = solvent used for gun cleaning by a shop without a
gun cleaner (lb/yr)
sred = solvent usage reduction from gun cleaning (0.6)
For Model Shop A:
Sgc - 407.5 lb/yr * (1 - 0.60)
163 lb/yr (22.3 gal/yr)
Thus, Model Shop A reduces its gun cleaning solvent usage from
407.5 lb/yr to 163 lb/yr by using a gun cleaner. Emissions are
reduced more than this by distilling and reusing the spent
solvent or by using it for waste fuel, as shown in Section B-5.3.
B-4.0 CALCULATION OF VOLATILE ORGANIC COMPOUND EMISSIONS FROM
MODEL SHOPS
Total baseline VOC's emitted by each model shop are
calculated by combining the VOC emissions from surface
preparation, coating applications, and gun cleaning.
B-4.1 volatile Organic Compound Emissions from Surface
preparation
Volatile organic compound emissions from surface preparation
are calculated by combining the amount of surface preparation
product used each year with the VOC content of the product, as
follows:
Esp - SP * Csp (B-7)
where:
Eon = annual VOC emissions from surface preparation
P (lb/yr)
SP - annual surface preparation product usage (gal/yr)
-------
CSD » VOC content of surface preparation
product (lb VOC/gal)
It is assumed that all model shops use surface preparation
products with average VOC levels of 6.4 lb VOC/gal. Thus, for
Model Shop A, which uses 5.25 gallons of surface preparation
products each year, VOC emissions will be:
Esp * 5.25 gal/yr * 6.4 lb VOC/gal
= 33.6 lb VOC emitted/year (0.017 ton/yr)
Table 4-1 (Chapter 4.0) shows emissions from surface preparation
for the eight model shops.
B-4.2 Volatile Organic Compound Emissions from CoatAna
Applications
Volatile organic compound emissions from coating
applications are calculated in a similar manner, by combining the
VOC content of each coating applied, less water and exempt
compounds, with the volume of coating used each year, as:
Ec C * VOC (B-8)
where:
Ec * annual emissions from coating (lb VOC/yr)
c * annual coating usage (gal/yr)
VOC * VOC content of coating (lb VOC/gal)
For Model Shop A, which uses 47.3 gallons of lacquer primer
surfacers with average VOC levels of 6.0 lb VOC/gal, as applied,
less water and exempt compounds, the VOC emissions from lacquer
use are:
Ec - 47.3 gal/yr * 6.0 lb VOC/gal
- 283.8 lb VOC/year (0.14 tons VOC/yr)
-------
This value is then added to the enamel primer surfacer VOC
emissions (37.7 lb VOC/yr) to derive the total primer surfacer
emissions of 3 21.5 lb VOC/yr or 0.16 ton VOC/yr from Model
Shop A, as shown in Table 4-2 (Chapter 4.0). Volatile organic
compound emissions from other coatings are calculated in this
same way.
B-4.3 Volatile Organic Compound Emissions fr-om Gun Cleaning
For model shops that use gun cleaners, passive (when the gun
cleaner is not in use) and active (during gun cleaning)
evaporative VOC losses still occur. Emissions from gun cleaners
are calculated by:
E„c - (TJ * 4 * AL) + (B-9)
(percent passive * 8760 * PL)
where:
Egc * annual emissions from a gun cleaner (lb/yr)
TJ =» total number of refinish jobs per year
4 - gun cleanings per job
AL " VOC emissions from active cycle (lb/cycle)
percent
passive ¦ fraction of time the gun cleaner is not in
use
8,760 - hours per year
PL ¦ VOC emissions from passive losses (lb/hr)
Typical emissions from gun cleaners are 0.059 lb/cycle for active
losses and 0.00463 lb/hr for passive losses.
For Model Shop C:
EgC - (525 jobs/yr * 4 cleanings/job * 0.059 lb/cycle)
+ (0.95 * 8760 hrs/yr * 0.00463 lb/hr)
- 162 lbs/yr (0.08 tons/yr)
-------
B-5.0 CALCULATION OF VOLATILE ORGANIC COMPOUND EMISSION
REDUCTIONS
The VOC emission reductions for each model shop are
calculated separately for surface preparation, coating
application, and gun cleaning.
B-5.1 Emission Reductions from Surface Preparation
To calculate the emission reductions that will be achieved
when lower voc surface preparation products are used, the
equation shown above in Section B-4.1 is used, with a surface
preparation product VOC level of 1.7 lb VOC/gal instead of the
conventional VOC level of 6.4 lb VOC.gal. The same amount of
surface preparation product can be used (1.5 pints/full vehicle,
0.15 pints/partial vehicle). Thus, if Model Shop A used lower
VOC surface preparation products, the resulting VOC emissions
each year would be calculated in a similar manner as
Equation B-7):
m SP * C*lsp (B —10)
* annual emissions from lower VOC surface
preparation products(lb VOC/yr)
¦ annual surface preparation product usage (gal/yr)
¦ VOC content of lower VOC surface preparation
product (lb VOC/gal)
Shop A:
5.25 gal/yr * 1.7 lb VOC/gal
8.9 lb VOC/year (0.004 ton VOC/yr)
(Chapter 4.0) shows the reduced surface preparation
for the eight model shops.
Emission reductions are calculated by subtracting emissions
from the lower VOC surface preparation product from the
conventional product emissions, as follows:
Elsp
Elsp
SP
clsp
For Model
Elsp
Table 4-1
emissions
-------
ESp " Eisp (B-ll)
emission reduction from shop using low VOC
surface preparation (lb VOC/yr)
annual emissions from same shop using
conventional surface preparation (lb/yr)
annual emissions from lower VOC surface
preparation products (lb/yr)
For Model Shop A:
ERsp - 33.6 lb/yr - 8.9 lb/yr
¦ 24.7 lb VOC/yr (0.013 ton VOC/yr)
Table 4-1 (Chapter 4.0) presents the VOC reductions for the eight
model shops realized by using lower VOC surface preparation
product.
B-5.2 Fmiaaion Reductions from Coating Applications
Emission reductions from the use of lower VOC coatings must
be calculated by first taking into account whether or not the
Option 1 and 2 coatings have higher solids contents than the
baseline coatings. The solids content of the coating can be
calculated with the equation shown above in Section B-2.2.
Once the solids content of each of the lower VOC coatings
has been calculated, the surface area to be refinished is
combined with the solids content, the desired film thickness, and
the transfer efficiency to calculate the amount of coating use
per year as shown in Section B-2.2.
The Option 1 and Option 2 coating VOC limits are shown
below. For the option 1 and 2 coatings, there is no delineation
between lacquer, enamel, or urethane coatings. Only the VOC
content, as applied, less water and exempt compounds,
distinguishes these coatings.
ERsp *
where:
ERsp *
Esp
Elsp
-------
VOC Content as Applied rib VQC/qal coating)
OPtiQn 1 Option 2
Primer?
Pretreatment Wash Primer 6.0 5.5
Primer Surfacer 3.8 2.1
Primer Sealer 4.6 4.6
TQP
-------
Emission reductions are calculated by subtracting the
Option 1 primer surfacer emissions from the conventional
emissions, as follows:
Epst "" Epsl (B-12)
emission reduction from Option 1 primer
surfacer (lb/yr)
total emissions from conventional primer
surfacer (lb/yr)
total emissions from Option primer surfacer
(lb VOC/yr)
326.6 lb/yr - 88.9 lb/yr
237.7 lb VOC/yr (0.12 ton VOC/yr)
Tables 4-4 and 4-5 (Chapter 4.0) show the percentage emission
reduction from baseline for the eight model shops for Option l
and Option 2 coatings, respectively.
B-5.3 Emission Reductions from Gun Cleaning
The calculations for emission reductions when a shop
installs a gun cleaner are similar to the calculations described
in Section B-4.3. The emission reductions achieved are partially
due to the reduced annual solvent use because the gun cleaning
solvent is recirculated and used for several gun cleanings.
Additional emission reduction is gained by distilling and reusing
the spent solvent or using it for a waste fuel. Emissions
reduction for a gun cleaner as opposed to no gun cleaner is
estimated to be 88 percent. Gun cleaning emissions for a shop
that installs a gun cleaner are calculated by:
ERpSi "
where:
ERpsi ¦
Epst "
Epsl *
For Model Shop A:
ERpsi "
-------
Egc = Eb * (1 " E^ed) (B-13)
where:
Egc = annual gun cleaning emissions from a shop after
installing a gun cleaner (lb VOC/yr)
Eb - annual gun cleaning emissions from the same shop
without a gun cleaner (lb VOC/yr)
Ere
-------
B-5.4 Emission Reductions from Add-On Control a
Emission reductions from add-on controls are calculated for
Model Shop H only. Add-on controls reduce VOC's from the exhaust
stream of the spray booth; thus, the source of the VOC's is from
the coating operations that take place in the spray booth.
Emissions from coatings after the installation of an add-on
control device are calculated by:
* [(100 - OCred/100)3 (B-15)
emissions after installation of an
add-on control device (ton VOC/yr)
total annual emissions from coatings
(ton voc/yr)
overall control (fraction)
Eac 38 ®tot
where:
Eac *
Etot *
ocred *
For Model Shop H, with total coating emissions of 11.37 tons
VOC/yr, and using catalytic incineration with an overall
reduction efficiency of 95 percent:
Eac - 11.37 tons VOC/yr * (1 - 0.95)
0.57 ton VOC/yr
Emission reduction is calculated by subtracting Eac from Etot' as
follows:
ERac m Eac " ®tot (B-16)
where:
ERac ¦ emissions reduction due to add-on control
device (ton VOC/yr)
Eac - emissions after the installation of an add-on
control (ton VOC/yr)
Etot * total annual emissions from coatings (ton/yr)
-------
For Model Shop H:
ERac - 11.37 tons VOC/yr - 0.57 ton VOC/yr
= 10.80 tons VOC/yr
Table 4-8 (Chapter 4.0) shows the coating emissions and emission
reductions for three add-on control devices applied to Model
Shop H.
-------
APPENDIX C
-------
APPENDIX C
COST CALCULATIONS
Sections C-1.0 through c-4.0 present the costing methodology
for the emission reduction techniques discussed in Chapter 3 and
the equipment required for implementation of those techniques.
Some costs were obtained from vendor quotes and some were
obtained from other reports.
In Section C-1.0 the calculations and assumptions used to
estimate the lower VOC surface preparation product costs are
shown. Section C-2.0 presents the calculations and assumptions
used to estimate the costs associated with the lower VOC
coatings. The gun cleaner cost calculations and assumptions are
presented in Section C-3.0. Section C-4.0 presents the
calculations and assumptions used to develop the add-on control
costs for Model Shop H. The following calculations use one model
shop (A) as an example. Calculations for the other model shops
are similar to those shown here for Model Shop A.
C-1.0 SURFACE PREPARATION COSTS
No capital costs are incurred in switching from conventional
to lower VOC surface preparation products, increased operating
costs are due to the higher price of the lower VOC product as
compared to conventional products. The following equation is
used to calculate the annual costs:
SPC ¦ SP * (LOVOC - CONV) (C-l)
where:
SPC » annual lower VOC surface preparation costs
($/yr)
SP - surface preparation usage (gal/yr)
LOVOC- lower VOC surface preparation price ($/gal)
CONV - conventional surface preparation price
($/gal)
For Model Shop A which uses 5.3 gallons per year,
SP - 5.3 gal/yr * ($i8.50/gal - $13.50/gal)
¦ $26.50/yr
The surface preparation costs for all model shops are shown in
Table 5-1 (Chapter 5.0).
tli.035
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C-2.0 COATING COSTS
This section presents the methods for calculating baseline
and Option 1 and Option 2 coating costs.
C-2.1 Baseline Coating Usage and Costs
To calculate baseline coating costs, baseline coating usage
is first calculated as outlined in Appendix B, Section B-2.2.
Table 5-2 (Chapter 5.0) presents the coating costs/gallon for the
baseline, Option 1 and Option 2 coatings. Baseline coating costs
are calculated for each coating type (lacquer, enamel, or
urethane) as follows:
PCb - Pb * PPb (C-2)
where:
PCb ¦ annual coating cost ($/yr)
Pb = annual coating usage as applied (gal/yr)
PPb = coating price as applied ($/gal)
For Model Shop A lacquer primer surfacers, at $19/gallon:
PCbi " 47.3 gal/yr * $i9/gal
= $898.70/yr
For Model Shop A enamel primer surfacers, at $36/gallon:
PCbe = 8.2 gal/yr * $36/gal
= $295.20/year
Total primer surfacer costs for Model Shop A are the sum of
lacquer and enamel primer surfacers.
PCb - PCbl + PCb.
- $898.70/yr + $295.20/yr
- $1,193.90/yr
Each coating type's usage and cost must be summed to
calculate total coating costs for a shop.
C-2.2 Option l and Option 2 Coating Usage and Costs
Coating usage for Option 1 and Option 2 is calculated using
the method outlined in Appendix B, Section B-2.2. Usage of the
Option 1 and 2 coatings is lower than for the baseline coatings
because the lower VOC coatings have higher solids contents.
tl».035
-------
However, the lower VOC coatings are higher in price so that there
may be an overall increase in coating cost, depending on how much
higher in price the lower VOC coatings are compared to the
baseline coatings.
The equation for calculating Option 1 and 2 coating costs is
similar to equation C-2:
PCi0W 58 Plow * PPlew (C —3)
where:
PClow » annual Option 1 (or Option 2) coating cost ($/yr)
Plow " Option 1 (or Option 2) coating usage (gal/yr)
PPiow ¦ Option 1 (or Option 2) coating price ($/gal)
For Model Shop A Option 1 primer surfacers, using 2 3.4 gallons/yr
at $50/gallon:
PCl0W - 23.4 gal/yr * $50/gal
- $1,170/yr
C-2.2 Sprav Booth Cost Calculation
For a semi-downdraft booth, installed equipment cost is
estimated to be $30,000. Equipment life is assumed to be
15 years and interest rate to be 10 percent. The capital
recovery factor is calculated as:
CRF - i * (i + l)n/((i + l)n - 1) (C-4)
where:
CRF ¦ capital recovery factor (fraction)
i - interest rate (fraction)
n ¦ equipment life (yrs)
For Model Shop A (and all other model shops without a spray
booth):
CRF - 0.1 * (0.1 + 1)1S/((0.1 + l)15 - 1)
» 0.1315
The annualized capital cost for a semi-downdraft spray booth is
calculated as:
tl».035
-------
ACC =
CRF * CC
(C-5)
where:
ACC
CRF
CC
annualized capital spray booth cost ($/yr)
capital recovery factor (fraction)
installed equipment cost ($)
For Model Shop A (and all other model shops without a spray
booth):
ACC - 0.1315 * $30,000
$3,944/yr
Maintenance costs for a spray booth are calculated as:
MC » 0.04 * CC (C-6)
where:
MC - maintenance cost ($/yr)
0.04 » estimated fraction of installed equipment cost
For Model Shop A (and all other model shops without a spray
booth):
MC - 0.04 * $30,000
* $l,200/yr
Operating costs are calculated as shown below, and were developed
from spray booth vendor information.1
For Model Shop A:
Electricity for fan, lights, and radiant heaters:
Note: Assumed price of electricity » $0.07/kWh
EC TJ * $1.02/job (C-7)
where:
EC » electricity cost ($/yr)
TJ - total number of refinishing jobs/year
$1.02* electricity cost per refinish job ($/job)
cc
incurred by maintenance
installed equipment cost ($)
Us.035
-------
EC ¦ 163 jobs/yr * $1.02/job
- $166.26/yr
Natural gas for makeup air heating:
Note: Assumed price of natural gas - $3.50/MMBtu
NG
TJ * $2.07/job
where:
NG
natural gas cost ($/yr)
TJ
total number of refinishing jobs/yr
$2.07-
natural gas cost per refinish job ($/job)
NG
163 * $2.07/job
=
$337.41/yr
Air filters:
AF
TJ * $4.12/job
where:
AF
air filter replacement cost ($/yr)
TJ
total number of refinishing jobs/yr
$4.12-
air filter cost per refinish job ($/job)
AF
163 * $4.12/job
$671.56/yr
G&A costs:
G&A - 0.04 * CC (C-10)
where:
G&A - general and administrative costs ($/yr)
0.04 ¦ estimated fraction of installed equipment cost
allocated for general and administrative costs
CC - installed equipment cost ($)
G&A - 0.04 * $30,000
$1,200/yr
Total annual costs for a semi-downdraft spray booth are shown in
Table 5-3 (Chapter 5.0) and are calculated as:
TAC - ACC + MC + EC + NG + AF + G&A (C-ll)
where:
tLs.035
-------
TAC = total annual costs ($/yr)
ACC = annualized capital cost ($/yr)
MC = maintenance costs ($/yr)
EC = electricity cost ($/yr)
NG = natural gas cost ($/yr)
AF = air filter cost ($/yr)
G&A = general and administrative costs ($/yr)
For Model Shop A, total annual costs are:
TAC ¦ $3,944 + $1,200 + $166.26 + $337.41 + $671.56 +
$ly200
$7,519.23/yr
C-2.3 Total Incremental Coating Costs
Total incremental coating costs for Option 1 and 2 coatings
over baseline coating costs are shown in Table 5-3 (Chapter 5.0)
and are calculated by:
TPC = PCl0W - PCb + TAC (C-12)
where:
TPC - total incremental Option 1 or 2 coating costs
($/yr)
pCl0W ¦ total annual Option 1 or 2 coating cost ($/yr)
PCb » total annual baseline coating cost ($/yr)
TAC - total annual spray booth cost ($/yr)
For Model Shop A (Option
TPC « $7,575/yr
$7,755/yr
1 coatings):
- $7,339/yr + $7,519/yr
C-3.0 GUN CLEANER COST CALCULATIONS
The installed equipment cost of a gun cleaner is estimated
to be $1,000, equipment life is assumed to be 10 years, and the
interest rate is assumed to be 10 percent. The capital recovery
factor is calculated as:
CRF - i * (i + l)n/((i + 1)" - 1) (C-13)
where:
-------
i = interest rate (fraction)
n = equipment life (yrs)
For Model Shop A (and all other model shops without a gun
cleaner):
CRF - 0.1 * (0.1 + l)lo/((0.1 + l)10 - i)
0.1627
The annualized capital cost for a gun cleaner is calculated as:
ACC - CRF * CC (C-14)
where:
ACC - annualized capital cost ($/yr)
Crf - capital recovery factor (fraction)
CC - installed equipment cost ($)
For Model Shop A (and all other model shops without a gun
cleaner):
ACC = 0.1627 * $1,000
$162.75
Maintenance costs for operating a gun cleaner are calculated as:
MC - 0.04 * CC (C-15)
where:
MC ¦ maintenance cost ($/yr)
0.04 - estimated fraction of installed equipment cost
incurred by maintenance
CC ¦ installed equipment cost ($)
For Model Shop A (and all other model shops without a gun
cleaner):
MC - 0.04 * $1,000
« $40/yr
Operating costs for a gun cleaner are shown below. Electricity
costs are assumed to be negligible because most gun cleaners use
compressed air.
-------
Solvent cost savings are calculated as:
SS » VOC * percent red * SC (C-16)
where:
SS = solvent cost savings ($/yr)
VOC = VOC emissions without gun cleaner (solvent
sprayed in air) (gal/yr)
percent
red » percent reduction in solvent usage with a gun
cleaner (fraction)
SC = solvent cost ($/gal)
For Model Shop A:
SS - 55.7 gal/yr * 0.60 * $5.00/gal
$167.10/yr
Total annual costs for shops installing a gun cleaner are:
TAC • ACC + MC - SS (C-17)
where:
TAC » total gun cleaner annual costs ($/yr)
ACC ¦ annualized capital cost ($/yr)
MC =¦ maintenance cost ($/yr)
SS = solvent cost savings ($/yr)
For Model Shop A:
TAC » $162.75 + $40 - $167.10
$35.65/yr
Table 5-4 (Chapter 5.0) presents the total annual gun cleaner
costs for Model Shops A, B, D, and F.
C-4.0 ADD-ON CONTROL COSTS
Add-on control costs are estimated only for Model Shop H.
c-4.i catalytic, Incineration with 3? Percent Beat P3
-------
CRF = i * (i + i)n/((i + I)n - l) (C-18)
where:
CRF = capital recovery factor (fraction)
i = interest rate (fraction)
n = equipment life (yrs)
For Model Shop H:
CRF = 0.1 * (0.1 + l)10/((O.l + l)l° - 1)
0.1627
The annualized capital cost for incineration is calculated
as:
ACC ¦ CRF * CC (C-19)
where:
ACC ® annualized capital cost ($/yr)
crf » capital recovery factor (fraction)
CC ¦ installed equipment cost ($)
For Model Shop H:
ACC - 0.1627 * $443,000
$72,076/yr
Maintenance labor costs for incineration are calculated as:
ML MT * 250 * MLR (C-20)
where:
ML « maintenance labor cost ($/yr)
MT ¦ maintenance time required per day (hr/day)
250 * operating days per year (days/yr)
MLR « maintenance labor rate ($/hr)
For Model Shop H:
ML - 0.5 hr/day * 250 days/yr * $15/hr
* $l,750/yr
Maintenance material costs are assumed equal to maintenance labor
costs.
-------
MM - ML
where:
MM = maintenance material
ML » $1,750/yr
(C-21)
costs ($/yr)
Operating costs are based on the assumed daily operating time for
the add-on control. The operating time for Model Shop H is
assumed to be 8 hrs/day.
For Model Shop H:
Electricity for fan (not including spray booth):
EC * t * 250 * KW * EP (C-22)
where:
EC ¦ annual electricity cost ($/yr)
t = operating time (hrs/day)
250 » operating days/yr
KW » fan power requirements (KW)
EP « electricity price ($/kWh)
EC = 8 hr/day * 250 day/hr * 25 KW * $0.07/kWh
$3,500/yr
Natural gas for air heating (not including spray booth):
NG - t * 250 * BTU * NGP (C-23)
where:
NG « annual natural gas cost ($/yr)
t « operating time (hrs/day)
250 - operating days/yr
BTU ¦ heat requirement (MMBtu/yr)
NGP » natural gas price ($/MMBtu)
NG » 8 hr/day * 250 day/yr * 6.5 MMBtu/hr * $3.50/MMBtu
$45,500/yr
Catalyst:
Catalyst (CAT) is assumed to last five years. Annual
catalyst cost is estimated to be $11,000.2
til.03J
-------
Operating labor cost:
Catalytic incineration is assumed to require 0.5 hours
of operating time/day, as shown below:
OL
t * LR * 5 days/wk * 50 wk/yr (C
where:
OL
annual operating labor cost ($/yr)
t
daily operating labor time (hr/day)
LR
labor wage rate ($/hr)
OL
0.5 hr/day * $14.00/hr * 5 days/wk * 50 wk/yr
$l,750/yr
Supervisory labor cost:
Supervisory labor cost is 15 percent of operating labor
cost.
SL - 0.15 * OL (C-25)
where:
SL ¦ annual supervisory labor cost ($/yr)
SL « 0.15 * $1,750
$262.50
G&A costs:
G&A = 0.04 * CC (C-26)
where:
G&A ¦ general and administrative costs ($/yr)
0.04 » estimated fraction of purchased equipment's cost
allocation for general and administrative costs
CC * installed equipment cost ($)
G&A - 0.04 * $443,000
$17,720/yr
Total annual cost for catalytic incineration is calculated as:
TAC « ACC + ML + MM + EC + NG + CAT + OL (C-27)
+ SL + G&A
where:
TAC = total annual cost for catalytic
incineration ($/yr)
-------
ML
MM
EC
NG
CAT
OL
SL
G&A
maintenance labor cost ($/yr)
maintenance material costs ($/yr)
electricity cost ($/yr)
natural gas cost ($/yr)
catalyst cost <$/yr)
annual operating labor cost ($/yr)
annual supervisory labor cost ($/yr)
general and administrative costs ($/yr)
For Model Shop H:
TAC ¦ $72,076 + $1,750 + $1,750 + $3,500 + $45,500
+ $11,000 + $1,750 + $263 + $16,620
$155,309/yr
Table 5-5 (Chapter 5.0) presents the total annual costs for
catalytic incineration for Model Shop H.
c-4.2 carbQn AflgogptiQn
Installed equipment cost of carbon adsorption is estimated
to be $90,000. This cost is annualized using an equipment life
of 15 years and an interest rate of 10 percent. The capital
recovery factor is calculated as:
CRF - i * (i + l)n/((i + l)n - 1) (C-28)
where:
CRF = capital recovery factor (fraction)
i - interest rate (fraction)
n ¦ equipment life (yrs)
For Model Shop H:
The annualized capital cost for carbon adsorption is
calculated as:
CRF » 0.1 * (0.1 + 1)10/((0.1 + l)10 - 1)
0.1627
ACC - CRF * CC
where:
ACC » annualized capital cost ($/yr)
CRF « capital recovery factor (fraction)
(C-29)
tU.033
-------
cc
installed equipment cost ($)
For Model Shop H:
ACC = 0.1627 * $90,000
$14,643/yr
Maintenance labor costs for carbon adsorption are calculated as:
ML ¦ MT * 250 * MLR (C-30)
where:
ML » maintenance labor cost ($/yr)
MT « maintenance time required per day (hr/day)
250 - operating days per year (days/yr)
MLR = maintenance labor rate ($/hr)
For Model Shop H:
ML - 0.5 hr/day * 250 days/yr * $14/hr
$1,750/yr
Maintenance material (MM) costs are equal to maintenance labor
costs.
MM ML $1,750 (C-31)
where:
MM - maintenance material costs ($/yr)
ML - $1,750/yr
Operating costs are based on the assumed daily operating time for
the carbon adsorber. The operating time for Model Shop H is
assumed to be 8 hrs/day. carbon is assumed to be desorbed and
regenerated off-site; therefore no credit is given for solvent
cost savings from on-site carbon regeneration.
For Model Shop H:
Electricity for fan (not including spray booth):
EC - t * 250 * KW * EP (C-32)
-------
EC - annual electricity cost ($/yr)
t » operating time (hrs/day)
250 = operating days/yr
KW ® fan power requirements (KW)
EP = electricity price ($/kWh)
EC 8 hr/day * 250 day/yr * 43 KW * $0.07/kWh
$6,020/yr
Carbon:2
C - 3,387 * t + 9,369 (C-33)
where:
C » annual carbon replacement cost ($/yr)
3,387= slope of line derived from linear curve fit
t - operating time (hrs/day)
9,369- y-intercept derived from linear curve fit
C - 3,387 * 8 hr/day + 9,369
$36,465/yr
Operating labor cost:
Carbon adsorption is assumed to require 0.5 hours of
operating time/day as shown below:
OL » t * LR * 5 days/wk * 50 wk/yr (C-34)
where:
OL « annual operating labor cost ($/yr)
t « daily operating labor time (hr/day)
LR » labor wage rate ($/hr)
OL ¦ 0.5 hr/day * $14.00/hr * 5 days/wk * 50 wk/yr
$l,750/yr
Supervisory labor cost (SL) is 15 percent of operating labor
costs.
SL
0.15 * OL
0.15 * $1,750/yr
$262.50/yr
tls.033
-------
G&A Costs (not including spray booth)i
G&A = 0.04 * CC (C-35)
where:
G&A = general and administrative costs ($/yr)
0.04 = estimated fraction of purchase equipment's cost
allocated for government and administrative costs
CC ¦ installed equipment cost ($)
G&A • 0.04 * $90,000
= $3,600/yr
Total annual cost for carbon adsorption is calculated as:
TAC - ACC + ML + MM + EC + C + OL + SL + G&A (C-3 6)
where:
TAC = total annual cost for carbon adsorption
($/yr)
ACC = annualized capital cost ($/yr)
ML ¦ maintenance time required per day (hr/day)
MM = maintenance materials costs ($/yr)
EC « electricity cost ($/yr)
c = annual carbon replacement cost ($/yr)
OL = annual operating labor cost ($/yr)
SL = annual supervisory labor cost ($/yr)
G&A = general and administrative costs ($/yr)
For Model Shop H:
TAC -
$14,643 + $1,750 + $1,750 + $6,020 + $36,465
+ $1,750 + $263 + $3,600
$66,241/yr
Table 5-5 (Chapter 5.0) presents the total annual costs for
carbon adsorption for Model Shop H.
tls.033
-------
REFERENCES
1. Telefax. Elder, C. , Auto Equipment Co., to Blackley, C.,
Radian Corporation. February 1991.
2. U.S. Environmental Protection Agency. Glossary for Air
Pollution Control of Industrial Coating Operations. 2nd
Edition. EPA-450/3-83-013R. U.S. Environmental Protection
Agency, Research Triangle Park, North Carolina. 1983.
tl».035
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APPENDIX D
CTG MODEL RULE FOR AUTOMOBILE REFINISHING OPERATIONS
This appendix presents a model rule to limit volatile
organic compound (VOC) emissions from automobile refinishing
operations. The model rule is provided for informational
purposes only. It is not binding on air quality management
authorities. The U. S. Environmental Protection Agency (EPA)
expects, however, that State and local air quality rules
developed pursuant to this Control Techniques Guideline (CTG)
will address all the factors covered in the model rule.
tls.035
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MODEL RULE TO LIMIT VOC EMISSIONS I .iOM
AUTOMOBILE REFINISHING OPERATIONS
(a) Applicability. This rule applies to automobile
refinishing operations performed in the following types of shops:
— auto body and repair shops;
— production paint shops?
— new car dealer repair and paint shops;
fleet operator repair and paint shops; and
— any other facility which coats vehicles under the
Standard Industrial Classification Code 7532 (Top, Body,
and Upholstery Repair Shops and Paint Shops).
This rule applies to refinishing operations for aftermarket
automobiles, motorcycles, and light- and medium-duty trucks and
vans. This includes dock repair of imported vehicles and dealer
repair of vehicles damaged in transit. It does not apply to
refinishing operations for other types of mobile equipment, such
as farm machinery and construction equipment.
(b) Definitions.
Adhesion promoter. A coating used to promote adhesion of a
topcoat on surfaces such as trim moldings, door locks, and door
sills, where sanding is impracticable.
Aftermarket automobiles. Vehicles that have been purchased
from the original equipment manufacturer.
Anti-alare safety coating. A low gloss coating formulated
to eliminate glare for safety purposes on interior surfaces of a
vehicle, as specified under the U.S. Department of Transportation
Motor Vehicle Safety Standards.
"As applied." The condition of a coating after dilution by
the user just prior to application to the substrate.
Elastomeric materials. Topcoats and primers that are
specifically formulated for application over flexible parts such
as filler panels and elastomeric bumpers.
tls.035
-------
Gun cleaner. A device made specifically to clean paint frcn
spray guns which recirculates solvent to clean a succession of
times, and is vapor tight when in use.
Light- and medium-dutv trucks and vans. Any truck or van
having a manufacturer's gross vehicle weight rating of 10,000
pounds or less.
Oversprav. That solids portion of a coating sprayed from an
applicator which fails to adhere to the part being sprayed.
(Applied solids plus overspray solids equal total solids
delivered by the spray application system.)
Primer. Any coating applied prior to the application of a
topcoat for the purpose of corrosion resistance, adhesion of the
topcoat, and color uniformity.
Precoat. The first coat applied to bare metal primarily to
deactivate the metal surface for corrosion resistance to a
subsequent waterborne primer.
Pretreatment wash primer. The first coat applied to bare
metal if solvent-based primers will be applied. This coating
contains a minimum of 0.5 percent acid by weight, is necessary to
provide surface etching, and is applied directly to bare metal
surfaces to provide corrosion resistance.
Primer sealer. An undercoat that improves the adhesion of
the topcoat, provides corrosion resistance, and promotes color
uniformity.
Primer surfacer. A coating which gives "body" to the
surface, fills in irregularities, and is intentionally thick
enough to permit sanding without cutting through to bare metal.
Specialty coatings and additives. Coatings or additives
that are reportedly necessary due to unusual job performance
requirements. These coatings or additives prevent the occurrence
of surface defects, and impart or improve desirable coating
properties. These products include uniform finish blenders,
elastomeric materials for coating flexible plastic parts, gloss
flatteners, and anti-glare/safety coatings.
tls.035
-------
Surface preparation products. Products used to limove wax,
tar, grease, and silicone from the surface to be refinished.
Topcoat. The last coat applied in a coating system.
Topcoats can be single-stage, basecoat/clearcoat, or
basecoat/midcoat/clearcoat.
Uniform finish blender. A thinner or low solids clear
solution which is used to melt overspray from a repaired area
into the unrepaired color.
Volatile organic compound (VOC). Any organic compound which
participates in atmospheric photochemical reactions. This
includes any organic compound except those which the
Administrator designates as having negligible photochemical
reactivity. For purposes of determining compliance with emission
limits, VOC will be measured by the approved test methods. Where
- such a method inadvertently measures compounds with negligible
photochemical reactivity, an owner or operator may exclude these
negligibly reactive compounds when determining compliance with an
emission standard.
(c) Operating Standards.
(1) Surface preparation products.
The VOC content of any surface preparation product must not
exceed 1.7 pounds VOC per gallon (lb VOC/gal) [2 00 grams VOC per
liter (g VOC/d)] of product as applied, including water.
1(2) Primers.
(i) Pretreatment wash primers and precoats.
(A) Under Option 1, the VOC content of any pretreatment
wash primer or precoat must not exceed 6.0 lb VOC/gal (720 g
VOC/f) less water, as applied.
Under Option 2, the VOC content of any pretreatment wash
primer or precoat must not exceed 5.5 lb VOC/gal (660 g VOC/f)
less water, as applied.
(ii) Primer surfacers.
(A) Under Option 1, the VOC content of any primer surfacer
must not exceed 3.8 lb VOC/gal (460 g VOC/f) less water, as
applied.
-------
Under Option 2, the VOC content of any primer t/arfacer must
not exceed 2.1 lb VOC/gal (250 g VOC/f) less water, as applied.
(iii) Primer sealers.
(A) The voc content of any primer sealer must not exceed
4.6 lb VOC/gal (550 g VOC/f) less water, as applied.
(3) Topcoats.
(i) Under Option 1, the VOC content of any topcoat must not
exceed 5.2 lb VOC/gal (620 g VOC/f) less water, as applied.
Under Option 2, the VOC content of any topcoat must not
exceed 4.5 lb VOC/gal (540 g VOC/f) less water, as applied.
(4) Additives and specialty coatings.
(i) The VOC content of any additive or specialty coating
must not exceed 7.0 lb VOC/gal (840 g VOC/f) less water, as
applied.
(ii) The use of all additives and specialty coatings in a
shop shall not exceed 5.0 percent by volume of all coatings
applied on a daily basis.
(d) Equipment Standards.
(1) Spray guns must be cleaned with a device that:
(i) recirculates solvent during the cleaning process so
that the solvent is used to clean a number of guns before being
disposed;
(ii) collects spent solvent so that it is available for
disposal;
(iii) is vapor tight during the cleaning operation; and
(iv) meets applicable fire safety and occupational safety
and health codes, laws, and regulations both in design and the
manner in which it can be used.
(e) Good Housekeeping Practices. The owner or operator
must ensure that the following good housekeeping practices are in
effect at all times:
(1) Fresh and spent solvent must be stored in containers
with gasket sealed, spring loaded covers.
(2) Waste paint, spent solvent, and sludge from gun
cleaners or in-house distillation units must be stored in gasket
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sealed containers until properly disposed. Proper disposal
includes releasing wastes to a licensed reclaiming or hazardous
waste management facility, or recycling with an in-house
distillation unit. In any case, suitable records must be
maintained to keep track of the volume or mass of material
involved.
(f) Recordkeeping Requirements. The owner or operator of
an affected facility must record the following types of
information. The information must be retained for a period of
time designated by the regulating agency and be readily available
to the regulating agency upon request.
(1) Number of partial and full refinishing jobs completed
on a daily basis.
(2) The VOC content, including water, of surface
preparation products used.
(3) The volume of surface preparation products used on a
daily basis.
(4) For each type of primer, topcoat, and specialty coating
used, daily records must be kept of:
(i) Volume of coating, catalyst, and reducer used;
(ii) Mix ratio of components in the coating?
(iii) VOC content of coating, less water, as applied.
(5) For each gun cleaner:
(i) A log of the quantity of replacement solvent added to
the gun cleaner on a monthly basis;
(ii) A log of the number of gun cleanings performed on a
daily basis;
(iii) A log of the amount of waste solvent removed from the
gun cleaner on a monthly basis. This should include
documentation of the amount released to a licensed reclaiming or
hazardous waste management facility; and
(iv) A log of thie dates and times of routine maintenance
and repairs.
tls.035
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