Volume II: Chapter 8

Methods for Estimating Air

Emissions from Paint, Ink, and

Other Coating Manufacturing

Facilities

February 2005
ii EIIP Volume II

Disclaimer

As the Environmental Protection Agency has indicated in Emission Inventory Improvement

Program (EIIP) documents, the choice of methods to be used to estimate emissions depends on

how the estimates will be used and the degree of accuracy required. Methods using site-specific

data are preferred over other methods. These documents are non-binding guidance and not rules. 

EPA, the States, and others retain the discretion to employ or to require other approaches that

meet the requirements of the applicable statutory or regulatory requirements in individual

circumstances. 
Chapter 8 – Paint, Ink, and Other Coating Manufacturing 02/01/05

EIIP Volume II iii

Table of Contents

Section Page

1.0 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.1-1

2.0 Source Category Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.2-1

2.1 Process Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.2-1

2.1.1 Preassembly and Premix . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.2-1

2.1.2 Pigment Grinding or Milling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.2-2

2.1.3 Product Finishing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.2-3

2.1.4 Product Filling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.2-3

2.1.5 Basic Flow Sheets for Coating Manufacturing Processes . . . . . . . . . . . . 8.2-3

2.2 Emission Sources . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.2-6

2.2.1 Process Operations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.2-6

2.2.2 Miscellaneous Operations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.2-7

2.2.3 Material Storage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.2-7

2.2.4 Equipment Leaks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.2-8

2.2.5 Spills . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.2-8

2.3 Process Design and Operating Factors Influencing Emissions . . . . . . . . . . . . . . 8.2-8

2.3.1 VOC Control Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.2-9

2.3.2 PM/PM10 Control Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.2-11

2.3.3 Equipment or Process Modifications . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.2-11

3.0 Overview of Available Methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.3-1

3.1 Emission Estimation Methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.3-1

3.1.1 Emission Factors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.3-1

3.1.2 Source-Specific Models . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.3-2

3.1.3 Material (Mass) Balance Calculations . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.3-2

3.1.4 Test Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.3-3

3.2 Comparison of Available Emission Estimation Methodologies . . . . . . . . . . . . . 8.3-4

4.0 Modeling Methods for Estimating Emissions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.4-1

4.1 Emission Model for Material Loading . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.4-3

4.2 Heat-Up Losses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.4-9

4.2.1 Option 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.4-10

4.2.2 Option 2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.4-15

4.3 Emission Model for Spills . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.4-19

4.4 Emission Model for Surface Evaporation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.4-22

4.5 Gas Sweep or Purge . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.4-26

4.5.1 Option 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.4-26

4.5.2 Option 2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.4-28

4.6 Solvent Reclamation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.4-36

4.7 Emission Model for Liquid Material Storage . . . . . . . . . . . . . . . . . . . . . . . . . . 8.4-40
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4.8 Emission Model for Wastewater Treatment ........................... 8.4-41

5.0 Other Methods for Estimating Emissions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.5-1

5.1 Emission Calculations Using Emission Factors . . . . . . . . . . . . . . . . . . . . . . . . . 8.5-1

5.1.1 Total VOC Emissions from Paint Manufacturing Facilities . . . . . . . . . . 8.5-1

5.1.2 VOC Emissions from Paint Mixing Operations . . . . . . . . . . . . . . . . . . . 8.5-5

5.1.3 VOC Emissions from Ink Manufacturing Facilities . . . . . . . . . . . . . . . . 8.5-7

5.1.4 Total and Speciated VOC Emissions from Solvent Reclamation . . . . . . 8.5-9

5.1.5 VOC Emissions from Parts Cleaning . . . . . . . . . . . . . . . . . . . . . . . . . . 8.5-11

5.1.6 VOC Emissions from Equipment Leaks . . . . . . . . . . . . . . . . . . . . . . . . 8.5-13

5.1.7 PM/PM10 Emissions from a Paint or Ink Manufacturing Facility . . . . . 8.5-14

5.2 VOC and PM Emission Calculations Using Material Balance . . . . . . . . . . . . . 8.5-15

5.3 Emission Calculations Using Test Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.5-16

6.0 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.6-1
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List of Figures

Figure Page

8.2-1. Basic paint manufacturing process flow diagram. . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.2-4

8.2-2. Basic Inks manufacturing process flow diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.2-5

List of Tables

Table Page

8.3-1. Estimated VOC Emissions Summary for the Bright Blue Paint Company . . . . . . . . 8.3-6

8.4-1. List of Variables and Symbols . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.4-2

8.5-1. List of Variables and Symbols . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.5-2

8.5-2. Emission Factors for Equipment Components at Coatings Manufacturing Facilities 8.5-13
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Chapter 8 – Paint, Ink, and Other Coating Manufacturing (9/30/04) 1.0 Introduction

EIIP Volume II 8.1-1

1.0 Introduction

The purpose of this guideline is to describe emission estimation techniques for point sources in

an organized manner and to provide concise example calculations to aid in the preparation of

emission inventories. While emissions estimates are not provided, the information presented in

this document may be used to select an emission estimation technique best suited to a particular

application. This chapter describes the procedures and recommended approaches for estimating

emissions from paint, ink, and other coating manufacturing operations, and it is intended to assist

industry as well as regulatory agency personnel.

As EPA has indicated in this and other EIIP documents, the choice of methods to be used to

estimate emissions depends on how the estimate will be used and the degree of accuracy required

and methods using site-specific data are preferred over other methods. Because this document

provides non-binding guidance and is not a rule, EPA, the States, and others retain the discretion

to employ or require other approaches that meet the specific requirements of the applicable

regulations in individual circumstances.

Section 2 of this chapter provides a brief overview of the types of coating manufacturing

processes, emission sources, and factors that affect emissions. Section 3 of this chapter provides

an overview of available emission estimation methods and an example showing the application

of different techniques to estimate emissions for a paint manufacturing facility. Note that the use

of site-specific emissions data is always preferred over the use of default values developed

through use of industry emission averages.

Section 4 of this chapter presents mathematical models and equations for estimating emissions

from several paint, ink, and other coating manufacturing operations. Section 5 of this chapter

describes other techniques for estimating emissions such as the use of emission factors and

material balances. Section 6 of this chapter presents references.
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2.0 Source Category Description

2.1 Process Description

This section provides a brief overview of paint, ink, and other coating manufacturing operations. 

The reader is referred to Control of VOC Emissions from Ink and Paint Manufacturing

Processes, April 1992, for additional background information. Paint and ink are suspensions of

finely separated pigment particles in a liquid that when spread over a surface in a thin layer will

form a solid, cohesive, and adherent film. Types of paints that are currently manufactured

include architectural coatings, product finishes (e.g., finishes for automobiles, machinery, metal

and wood furniture, and appliances), and special purpose coatings (e.g., industrial new

construction and maintenance paints, traffic marking paints, and marine paints). Approximately

80 percent of architectural coatings are water-based (Census Bureau, 1997). However,

solvent-based paint is still predominantly used for product finishes and special-purpose coatings. 

Inks that are currently manufactured include letterpress, lithographic and offset, gravure, and

flexographic inks. Letterpress and lithographic inks are typically classified as paste inks. 

Gravure and flexographic inks are typically water- or solvent-based and are classified as liquid

inks (NAPIM, 1996). Specialty ink products include textile and silk screen ink, invisible inks,

powder inks, carbon paper, typewriter, and duplicating inks. Paint, ink, and other coating

manufacturing can be classified as a batch process and generally involves the blending/mixing of

resins, pigments, solvents, and additives. Traditional paint, ink, and other coating manufacturing

consists of four major steps: 

# Preassembly and premix;

# Pigment grinding/milling/dispersing;

# Product finishing/blending; and

# Product filling/packaging.

These steps are described in more detail in the sections below. 

2.1.1 Preassembly and Premix

In the preassembly and premix step, liquid raw materials are assembled and then mixed in

containers to form a viscous material to which pigments are added. For solvent-based paints, the

raw ingredients include resins, organic solvents, plasticizers, dry pigment, and pigment

extenders. Raw materials used in the preassembly and premix step for water-based paints

include water, ammonia, dispersant, pigment, and pigment extenders. Raw materials for ink

manufacturing include pigments, oils, resins, solvents, and driers. The premix stage results in the

formation of an intermediate product that is referred to as the base or mill base. The type of

equipment used in the premix step depends on the batch size and the type of coating being
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produced. Drums equipped with a portable mixer may be used for drum-sized batches. These

mixers normally have an impeller with three or four blades. Other materials made in portable

mix tanks may be blended using larger, permanent high-speed dispersers or variable-speed

mixers fitted with paddle, propeller, turbine, or disc-type agitators. Coating manufacturing

facilities may use typical grinding equipment to accomplish the premix operations. This

approach, common with water-based paints and inks, eliminates the need to transfer the material

to another type of equipment for the grinding/milling step described below. 

2.1.2 Pigment Grinding or Milling

Pigment grinding or milling entails the incorporation of the pigment into the liquid base of the

coating to yield a fine particle dispersion. The three stages of this process include wetting,

grinding, and dispersion, which may overlap in any grinding operation. The wetting agent,

normally a surfactant, wets the pigment particles by displacing air, moisture, and gases that are

adsorbed on the surface of the pigment particles. Grinding is the mechanical breakup and

separation of pigment clusters into isolated particles and may be facilitated by the use of grinding

media such as pebbles, balls, or beads. Finally, dispersion is the movement of wetted particles

into the body of the liquid vehicle to produce a particle suspension. There is a wide array of

milling equipment. The type of equipment used depends on the types of pigments being handled

(Noyes, 1993). More commonly used equipment include the following: roller mills, ball and

pebble mills, attritors, sand mills, bead and shot mills, high-speed stone and colloid mills,

high-speed dispersers, high-speed impingement mills, and horizontal media mills. However, it

should be noted that roller and ball mills are somewhat outdated methods in current pigment base

manufacturing technology. Additionally, these types of equipment are usually associated with

elevated levels of volatile organic compound (VOC) emissions due to their more open design. 

Roller mills may have from one to five rolls that grind pigments into vehicles. Most coating

manufacturing facilities that use roller mills operate with conventional three-roll mills. Roller

mills are labor intensive, requiring highly skilled operators. Their lack of speed and high

operating cost make them unsuitable for large-volume production. The use of roller mills is

confined to the manufacture of very high quality paint and inks and viscous pigmented products

that require fine dispersion and clean color (EPA, 1992a).

High-speed dispersion is the most universally used method of mixing in the paint, ink, and other

coating manufacturing industry. Some paint and ink blends are manufactured entirely in one

piece of equipment using high-speed, disk-type impellers. Because no grinding media are

present in the mixing vat, pigment disperses on itself and against the surfaces of the rotor. While

high-speed disk dispersion may work well for some products such as undercoats and primers, it

may not be appropriate for high-quality paints and inks. It can, however, be used for premix

operations of high-quality paints and inks, thus reducing the number of passes in a media mill or

reducing the amount of time spent in a ball mill. 
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2.1.3 Product Finishing

Final product specifications for color, viscosity, and other coating characteristics are achieved in

the product finishing step. This process generally consists of thinning, tinting, and blending. 

Most of the solvents, tints, and shades are added during this operation (Fisher et al., 1993). 

Product finishing activities for solvent-based paints and inks involve adding various

combinations of pigments, organic solvents, and resins. For water-based coatings, a preservative,

an antifoaming agent, a polyvinyl acetate emulsion, and water are added at this step of the

manufacturing process. Blending is the process of mixing the added ingredients to meet product

specifications. Blending may consist of additional milling in a ball mill or added mixing and

dispersing in a portable mix tank/high-speed disperser setup. 

2.1.4 Product Filling

The final step in the paint, ink, and other coating manufacturing process is the product filling

operation. During the filling step, filtration is performed to remove impurities and to catch small

particles of grinding media. Coatings may be filtered in a variety of ways and the end use of the

product determines the type of filtration required. Some products require only a cloth bag filter;

other products require filtering equipment such as strainers or sieves (Fisher et al, 1993). Once

the material has been filtered, it can be transferred into pails, drums, totes, tank wagons, or other

containers for shipment. Filling may be accomplished either manually or mechanically

depending on the number and size of the containers to be filled. 

2.1.5 Basic Flow Sheets for Coating Manufacturing Processes

Figures 8.2.1 and 8.2.2 present basic paint and ink manufacturing process diagrams.
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Bulk Liquid

Raw

Material

Drum

Liquid

Raw

Material

High Speed

Dispersion

Tank

Dust 

Collector

Fill

Tub

1/4, 1, 5

Gallon

55

Gallon

Thin&

Shade

Tank

Recovered

Particular

Matter

Milling

Dry Raw

Materials

Figure 8.2-1. Basic paint manufacturing process flow diagram.
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High Speed

Dispersion

Tank

Dry Raw

Materials

1/4, 1, 5

Gallon

Drum

Liquid

Raw

Materials

Bulk Liquid

Raw

Materials

Roll Milling

Figure 8.2-2. Basic Inks manufacturing process flow diagram.
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8.2-6 EIIP Volume II

2.2 Emission Sources

The majority of emissions that occur from paint, ink, and other coating manufacturing operations

are from volatile organic compounds (VOCs) that evaporate during manufacturing. Particulate

matter emissions may also occur from the handling of solid powders that are used in

manufacturing. 

Several air emission sources have been identified for paint, ink, and other coating manufacturing

operations; they are as follows:

# Process operations

# Related miscellaneous operations

# Material storage

# Equipment leaks

# Spills and other abnormalities

2.2.1 Process Operations

Process operations cover emissions from mixing, grinding, blending, and filling activities. 

Emissions from these operations can generally be classified in one of the following four

categories. 

Material Loading Emissions. VOC emissions may occur during material loading of mixing and

grinding equipment due to the displacement of organic vapors. VOCs may be emitted from a

mixing tank when the device is uncovered or when a lid is open. For certain grinding equipment,

VOCs may be released from the chute through which ingredients are added.

Particulate matter (PM) and PM equal to or less than 10 micrometers in diameter (PM10)

emissions may also occur during the material loading process from handling of pigments and

other solids. VOC and PM emissions during material loading emissions may occur as point

source or fugitive, depending on whether a PM emissions collection system is in place. 

Heat-Up Losses. Heat-up losses occur during the operation of high-speed dispersers, ball and

pebble mills, and similar types of dispersing equipment. During the grinding/dispersing process,

there is a rise in temperature as some of the kinetic mixing energy is converted to thermal energy. 

This rise in temperature in many cases is controlled through the use of cold water jackets on the

process vessel. As the VOCs in the mixers heat up, the vapor in the headspace expands and leads

to solvent emissions from the equipment. Emissions that escape the process equipment through

loose fittings or duct connections and enter the room air are considered to be fugitive emissions. 

Emissions that exit the process equipment through the vent duct to the emissions handling

system are considered to be process emissions. (Fisher et al, 1993)

Surface Evaporation. Surface evaporation may occur during mixing, dispersing, and blending

operations if the vessel contents are exposed to the atmosphere. For certain types of mixing and
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EIIP Volume II 8.2-7

grinding equipment, VOCs may be emitted through agitator shaft openings or around the edges

of a vessel lid. VOC emissions from older vertical media mills (e.g., sand mills, bead mills, and

shot mills) may occur from the exposed filtering screen.

Filling Losses. Emissions from product filling occur during transfer and free-fall into the

receiving container. 

2.2.2 Miscellaneous Operations

In addition to typical process operations associated with paint, ink, and other coating

manufacturing, miscellaneous operations can generate emissions (primarily in the form of

VOCs). These operations are discussed below: 

Solvent Reclamation. Solvent reclamation refers to the purification of dirty or spent solvent

through use of a distillation device. VOC emissions occur from loading solvent into the

distillation equipment, operation of the distillation equipment, and spillage. Emissions from

loading and spilling are classified as fugitive, while emissions from operation of the equipment

are generally discharged through a condenser vent and are thus classified as point source. 

Cleaning. Cleaning is an important ancillary part of paint, ink, and other coating manufacturing

processes. Process equipment may be cleaned with solvent as often as after each batch. VOC

emissions result from charging the mixer or disperser with solvent and can be characterized as

fugitive. In addition to this type of cleaning, small items used in the process may be cleaned by

washing with solvents in a cold cleaner or open-top vapor degreaser. Of the two technologies,

the use of a cold cleaner is more common. VOC emissions from this type of cleaning are

classified as fugitive. 

Wastewater Treatment. A paint, ink, or other coating manufacturing facility may use a

wastewater treatment system to treat contaminated water generated during the process (e.g.,

water that has been used to clean equipment used in the production of water-based coating). 

Wastewater treatment systems generally consist of a series of surface impoundments that are

used for equalization, neutralization, aeration, and clarification of the waste stream. Fugitive

VOC emissions may occur from each type of basin. Procedures used to estimate emissions from

wastewater treatment facilities are described in detail in Volume II, Chapter 5, Preferred and

Alternative Methods for Estimating Air Emissions from Wastewater Collection and Treatment. 

2.2.3 Material Storage

Various types and sizes of storage tanks are used to store solvents and resins used in the paint,

ink, and other coating manufacturing processes. Most of these tanks have a fixed-roof design

(Fisher et al., 1993). The two significant types of emissions from fixed-roof tanks are breathing

and working losses. Breathing loss is the expulsion of vapor from a tank through vapor

expansion and contraction that result from changes in ambient temperature and barometric

pressure. This loss occurs without any liquid level change in the tank. The combined loss from
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8.2-8 EIIP Volume II

filling and emptying tanks is called working loss. Evaporation during filling operations results

from an increase in the liquid level in the tank. As the liquid level increases, the pressure inside

the tank exceeds the relief pressure and vapors are expelled from the tank. Evaporative

emissions during emptying occur when air drawn into the tank during liquid removal becomes

saturated with organic vapor and expands, expelling vapor through the vapor relief valve (EPA,

1995a). Emissions from tanks are characterized as a point source because VOCs are released

through a vent. 

2.2.4 Equipment Leaks

In order to transport stored materials (e.g., organic solvents and resins) from storage tanks to the

paint, ink, or other coating manufacturing operation, a network of pipes, pumps, valves, and

flanges is employed. As liquid material is pumped from the storage tanks to the particular

process area, the pipes and supporting hardware (process line components) may develop leaks

over time. When leaks occur, volatile components in the transported material are released to the

atmosphere. This generally occurs from the following process line components: 

# Pump seals

# Valves

# Compressor seals

# Safety relief valves

# Flanges

# Open-ended lines

# Sampling connections.

Emissions from equipment leaks can be characterized as fugitive and are described in detail in

Volume II, Chapter 4, Preferred and Alternative Methods for Estimating Fugitive Emissions from

Equipment Leaks. Emission factors for pumps, valves, and connectors at coating manufacturing

facilities are also discussed in section 5.1.6 of this chapter.

2.2.5 Spills

Solvents, resins, or product may be accidentally spilled during manufacturing or cleaning

activities. Materials that are spilled onto the ground may spread over an area, vaporize, and thus

result in an air emission (EPA, 1987). Such an emission would be characterized as fugitive.

2.3 Process Design and Operating Factors Influencing Emissions

VOC and PM emissions from paint, ink, and other coating manufacturing may be reduced

through the use of add-on control systems or through equipment and process modifications.
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2.3.1 VOC Control Systems

A VOC control system typically consists of a capture device and a removal device. The capture

device (such as a hood or enclosure) captures the VOC-laden air from the emission area and

ducts the exhaust air stream to removal equipment such as a recovery device or a destructive

control device. In either case, the purpose of the control device is to remove VOCs from the

exhaust air stream. The overall efficiency of a control system is a function of the specific

removal efficiency for each device in the system. 

Example recovery devices:

1. Condensers are one of the most frequently used control devices in industry. They

work by reducing the temperature of the emission exhaust gas to a cold enough

temperature so that VOC vapors are recovered through condensation. One problem

that is frequently encountered in the coating manufacturing industries is that the

solvent vapors in the emission exhaust gas may have a fairly low dew point

temperature. This is because normal processing temperatures are generally low and

many exhaust systems provide a high level of dilution from outside air that further

reduces the dew point temperature of the gas. 

2. Adsorption Devices that incorporate activated carbon are capable of removing VOC

vapors from exhaust emission streams to very low levels in the final gas stream. 

Large scale adsorption based recovery systems normally have two or more activated

carbon adsorption chambers. One carbon chamber is being used to remove VOCs

from an emission stream while the spent carbon chamber is being regenerated. VOCs

are recovered from the system during the regeneration phase. Steam is routed into the

saturated carbon bed to cause the VOCs to desorb from the carbon and condense at

the condenser. Once VOC liquids have been collected then they may be recycled or

further purified prior to reuse in the manufacturing operation. 

3. Dust collectors are used to collect particulate matter from the emission stream. Dust

collectors are constructed in many different designs. However, one style that is

commonly used in the coating manufacturing industry is a bag house design. A bag

house consists of a large rectangular housing with many internal banks of vertically

mounted filter bags. The emission stream enters the bag house through the side inlet,

passes through the bag filter media, and exits the unit through the discharge port at the

top. Particulate matter builds up on the filter media until it is shaken off by pulses of

compressed air from within each bag. The dust that falls from the bags during the

pulsing process is collected at the lower section of the bag house and finally

discharged through the solids outlet to a drum or other container. When designing a

bag house for an installation it is important to select the appropriate filter media and

surface area for the particulate matter to be collected. The pore size of the filter cloth

will determine the removal efficiency of the overall unit. 
Chapter 8 – Paint, Ink, and Other Coating Manufacturing 02/01/05

8.2-10 EIIP Volume II

4. A floating roof on a storage tank helps to reduce solvent emissions by eliminating the

headspace that is present in conventional storage tanks. For the conventional storage

tank, air that is saturated with solvent vapors exits the vessel as the surrounding

temperature increases during the day. Outside air then reenters the vessel during the

evening hours as the surrounding temperature decreases and the daily cycle prepares

to be repeated. Additionally, when a conventional storage tank is filled periodically

then emissions occur by way of displacement. A floating roof moves up and down

the vessel vertical walls as the level of the storage tank changes. Since the vessel

contains no headspace all breathing and filling losses are avoided. 

Example destructive control devices:

1. Catalytic Incinerators are used to reduce VOCs from process exhaust gases from paint

spray booths, ovens, and other process operations. The catalyst section operates at

between 315/C to 400/C to convert VOC to CO2 and H2O. A properly designed and

installed system can achieve a VOC destruction efficiency of greater than 95%.

2. Thermal Incinerators control VOC levels in a gas stream by passing the stream

through a combustion chamber where the VOCs are burned in air at temperatures

between 700/C to 1,300/C. Fuel is burned in the unit to supply the necessary heat for

decomposition of the VOC’s. Heat exchangers may also be installed as part of the

unit to conserve energy by warming the inlet air stream with the hot exhaust gases. 

3. Venturi Scrubbers are used to remove particulate material from vent exhaust streams. 

These units normally incorporate a spray nozzle section where liquid is discharged at

a high velocity, a mixing section where liquid droplets contact the incoming emission

gas stream, and a settling/separation section where scrubber fluid is recycled to the

inlet spray nozzle and the exit gas is discharged to the atmosphere or to a secondary

control device. 

4. Enclosed Oxidizing Flares convert VOCs into CO2 and H2O by way of direct

combustion. Normally an enclosed oxidizing flare is used when the waste gas is rich

enough in organic content to be its own fuel source. If the process gas stream does

not contain an adequate level of combustible VOCs then additional fuel must be

supplied for effective operation. 

The removal efficiency for each control device is a function of the specific design of the unit and

how well its capability matches the intended application. Before selecting pollution equipment

one should consult different manufacturers and/or engineering firms to determine the most

appropriate control device solution for a given application. 
Chapter 8 – Paint, Ink, and Other Coating Manufacturing 02/01/05

EIIP Volume II 8.2-11

2.3.2 PM/PM10 Control Systems

PM/PM10 control systems for the paint, ink, and other coatings manufacturing industry consist

of a capture device paired with a control device that is typically a fabric filter (bag house). These

systems are typically employed to reduce PM emissions from charging pigments and other solids

into mixing and grinding devices. The captured dust may be recycled or sent for off-site disposal

or treatment.

Bag houses remove particulate material from an emission gas stream by passing the emission

stream through engineered fabric filter tubes, envelopes, or cartridges. Particulate material is

retained on the filter media as the clean air is discharged to the atmosphere. Vibrators or timed

air blast are used for removing and discharging the dust that has been collected in the unit. When

identifying a bag house for an application it is important to consider the particle size in the

emission stream, the particle size control requirements, the air flow rate of the emission stream,

and the bag filter surface area requirements. Additionally, it is important to identify the

appropriate chemical resistance requirements for the materials of construction in the unit. 

Fabric filters are least efficient with particles 0.1 to 0.3 :m in diameter and with emission

streams of high moisture content. When operated under optimum conditions, they can generally

achieve control efficiencies of up to 99+ percent (EIIP, 2000). However, typical control

efficiencies range from 95 to 99 percent. 

2.3.3 Equipment or Process Modifications

Most coatings manufacturing facilities reduce VOC emissions through equipment or process

modifications. Some of these techniques will also reduce PM emissions. Modifications include

those discussed below. 

Tank Lids. Tank lids are the most common equipment modification used during paint, ink, and

other coating manufacturing activities to control VOC emissions.

Modified Milling Equipment. VOC and PM emissions may be reduced by converting older

milling equipment to closed systems.

Use of Pigments in Paste Form. PM emissions may be reduced by using pigments that have

been wetted or mixed with resins. Since these pigments are wet, dust is not generated when the

package is opened and as pigment is dumped into mixing vessels (Noyes, 1993).

Product Reformulation. Production of coatings that contain reduced or no VOCs will reduce

VOC emissions from coatings manufacturing facilities. High-solids and water-based coatings

contain less VOCs than traditional solvent-based products. Powder coatings and the majority of

radiation-curable paints and inks contain no VOCs.
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EIIP Volume II 8.3-1

3.0 Overview of Available Methods

3.1 Emission Estimation Methods

Several methods are available for calculating emissions from paint, ink, and other coating

manufacturing operations. The best method to use depends upon the emission source being

evaluated, available data, how the estimates will be used, and the degree of accuracy required in

the estimate. Although multiple methods are identified for some operations, this document does

not mandate any emission estimation method. Industry personnel using this manual should

contact the appropriate state or local air pollution control agency regarding suggested methods

prior to their use.

This section discusses the methods available for calculating emissions from paint, ink, and other

coating manufacturing operations. A discussion of the sampling and analytical methods

available for monitoring each pollutant is provided in Chapter 1 of this volume, Introduction to

Point Source Emission Inventory Development.

Estimation techniques for storage tank emissions are discussed in Chapter 1 of this volume, and

procedures for estimating emissions from wastewater are described in Chapter 5. This chapter

focuses on estimating emissions from process operations, miscellaneous operations, and spills. 

This chapter also presents equipment leak emission factors for coating manufacturing; additional

equations and factors for calculating emissions from equipment leaks are discussed in Chapter 4.

3.1.1 Emission Factors

An emission factor can be defined as a pollutant emission rate relative to a level of source

activity. Emission factors are typically based on the results of source tests performed at an

individual plant or at one or more facilities within an industry. Chapter 1 of this volume contains

a detailed discussion of the reliability/quality of available emission factors.

Emission factors may be used to calculate total VOC and PM emissions from a paint and ink

manufacturing facility, as well as emissions from specific types of equipment typically found at

such a facility. These types of equipment include the following:

# Process equipment;

# Solvent reclamation systems;

# Parts washing equipment; and

# Process piping.
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8.3-2 EIIP Volume II

EPA-approved emission factors for these sources may be found in AP-42, the Locating and

Estimating series of documents, the Factor Information and REtrieval (FIRE) System, and/or

Protocol for Equipment Leak Emission Estimates (EPA, 1995g). Emission factors may also be

available through trade associations such as the National Association of Printing Ink

Manufacturers, Inc. (NAPIM).

Use of paint manufacturing emission factors from Section 6.4 of AP-42 and ink manufacturing

emission factors from Section 6.7 of AP-42 is generally accepted by regulatory agencies, and

their use in calculating total facility or process-specific emissions is more cost-effective than

collection and analysis of air samples or use of emission models. Additionally, there are

potentially significant limitations with the material balance approach.

3.1.2 Source-Specific Models

Theoretical, more complex “models” or equations can be used for estimating emissions. Use of

emission models/equations to estimate emissions from paint, ink, and other coating

manufacturing facilities is a more complex and time-consuming process than the use of emission

factors. Emission models/equations require more detailed inputs than use of emission factors;

however, they provide emission estimates based on site-specific conditions.

Emission estimating models/equations are available for the following types of emissions found at

paint, ink, or other coating manufacturing facilities:

# Material loading

# Heat-up losses from dispersion/grinding activities

# Surface evaporation during mixing/blending operations

# Filling

# Gas sweep or purge

# Cleaning solvent loading

# Solvent reclamation

# Material storage

# Spills

# Wastewater treatment.

Inputs for theoretical models/equations generally fall into the following categories: 

chemical/physical properties of the material(s) involved (e.g., vapor pressure, vapor molecular

weight), operating data (e.g., amount of material processed, operating hours) and physical

characteristics/properties of the source (e.g., tank color, tank diameter).

3.1.3 Material (Mass) Balance Calculations

The material balance approach to emissions estimation considers the given facility as a sort of

“black box,” where one compares the total quantity of raw materials consumed versus amounts

of materials leaving the facility as product or waste. Waste can consist of used filter bags or
Chapter 8 – Paint, Ink, and Other Coating Manufacturing 02/01/05

EIIP Volume II 8.3-3

cartridges, spent solvent or still bottoms, dust collector material, pigment bags and/or drum

residue, and wastewater (NPCA, 1995).

Calculating emissions from a paint or ink manufacturing facility using material balance appears

to represent a straightforward approach to emissions estimations. However, few facilities track

material usage and waste generation with the overall accuracy needed for application of this

method, and inaccuracies associated with individual material tracking or other activities inherent

to each material handling step often accumulate into large deviations. Because emissions from

specific materials are typically below 1.5 percent of gross consumption, an error of only

± 5.0 percent in any one step of the operation can significantly skew emissions calculations. 

Potential sources of error in the material balance calculation method include the following:

# The delivery of bulk raw materials at a paint or ink manufacturing facility is often

tracked by volume, not by weight. Since density will vary with temperatures, the

actual mass per unit volume of materials delivered in the summer may be less than

that received in the winter.

# Raw materials received by paint or ink manufacturing facilities may potentially be

used in hundreds or thousands of finished products. In order to complete the material

balance, it is crucial that the exact quantity and speciation of each material shipped

off-site in the product be known. For many facilities, it is extremely difficult, to

accurately track the distribution of specific raw materials across their entire product

line.

# The amount of raw material contained in waste must also be considered. This may

involve precise analysis of the concentration of the material of interest in each waste

stream.

# Batch production of paint or ink often requires the manual addition of raw materials. 

Sometimes these additions are not accurately measured or recorded (NPCA, 1995).

3.1.4 Test Data

Testing can be performed to quantify point source or fugitive emissions. In point source testing,

effluent gas samples are usually collected from a stack using probes inserted through a port in the

stack wall. Pollutants in the gas sample are collected in or on various media that are

subsequently sent to a laboratory for analysis. Pollutant concentrations are obtained by dividing

the amount of pollutant collected during the test by the volume of gas sampled. Emission rates

are then determined by multiplying the pollutant concentration by the volumetric stack gas flow

rate. Because there are many steps in the stack sampling procedures where errors can occur, only

experienced stack testers should perform such tests.

Industrial hygiene data (concentrations) can be used in conjunction with exhaust system flow

rates to calculate fugitive emissions from a room, floor, or building. Direct-reading instruments
Chapter 8 – Paint, Ink, and Other Coating Manufacturing 02/01/05

8.3-4 EIIP Volume II

that may be used to obtain an instantaneous reading of vapor concentrations include

photoionization detectors, portable infrared spectrophotometers, and portable gas

chromatographs (NPCA, 1995).

Use of stack and/or industrial hygiene test data is likely to be the most accurate method of

quantifying air emissions from paint, ink, and other coating manufacturing operations. However,

collection and analysis of air samples from manufacturing facilities can be very expensive and

especially complicated for coating manufacturing facilities where a variety of VOCs are emitted

and where most of the emissions may be fugitive in nature. Test data from one specific process

may not be representative of the entire manufacturing operation and may provide only one

example (a snapshot) of the facility’s emissions.

To be representative, test data would need to be collected over a period of time that covers

production of multiple coating formulations. It may be necessary to sample multiple production

areas. In addition, these methods do not address fugitive emissions that occur outside of a

building. If testing is performed, care should be taken to ensure that a representative operational

cycle has been selected. If possible, full cycles should be monitored as opposed to portions of

cycles.

VOC losses from certain operations (e.g., filling of containers) may also be measured by

performing a study using a gravimetric analysis such as American Society for Testing and

Materials (ASTM) Standard D2369: Test Method for Volatile Content of Coatings.

Chapter 1 of Volume II in this series provide information regarding test data quality.

3.2 Comparison of Available Emission Estimation Methodologies

The best method to use depends upon the emission source being evaluated, available data, how

the estimates will be used, and the degree of accuracy required in the estimate. In general, a

more accurate method will require greater resources than a less accurate method. Case study 8.3-

1 presents estimates for all of the operation at a paint manufacturing facility. For some

operations, multiple estimates are provided showing the impact of different techniques on the

results.
Chapter 8 – Paint, Ink, and Other Coating Manufacturing 02/01/05

EIIP Volume II 8.3-5

Case Study 8.3-1: The Bright Blue Paint Company

Description

The Bright Blue Paint Company produces a variety of related paint products that can be considered

to have similar formulations. The total production rate is about 2,500,000 gal/yr.

The four main manufacturing operations at the Bright Blue Paint Company are:

# Preassembly and premix;

# Pigment grinding/milling;

# Product finishing/blending; and

# Product filling/packaging. 

The batch begins with mixing of raw materials in a high speed disperser. The material from the

disperser is then transformed to a thindown tank where additional solvent is added. The final

product is then transferred to shipping containers. Total batch size is about 1,700 gallons.

Liquid storage of paint ingredients and cleaning compounds is in bulk tanks ranging from 2,500 to

10,000 gallons and in 55-gallon drums. Powder ingredients are stored in paper sacks or fiber drums

ranging from 10 to 200 pounds. 

Equipment is cleaned after each batch. Approximately 75,000 gallons of cleaning solvents are used

for equipment cleaning each year. Small parts are also cleaned as necessary using an open-top vapor

degreaser. 

Emission Sources

Emission sources for this facility include:

# Mixing (material loading, heat-up, gas sweep, and surface evaporation);

# Filling losses;

# Cleaning (parts, mixers/tanks);

# Solvent reclamation;

# Material storage;

# Equipment leaks; and

# Spills. 

Emissions

Emissions, the emission estimation method selected, and supporting data for this facility are

summarized in Table 8.3-1.
Chapter 8 – Paint, Ink, and Other Coating Manufacturing 02/01/05

8.3-6 EIIP Volume II

Table 8.3-1. Estimated VOC Emissions Summary for the

Bright Blue Paint Company

Emission Event

VOC Emissions, lb/yr

ABC Data and Assumptions

Filling dispersion vessels

A: Saturation factor = 0.6

B: Saturation factor = 1.0

C: Saturation factor = 1.45

(Equation 8.4-1)

2683 4472 6485 C 1,008,000 gal toluene

C 564,000 gal MEK

C 2,200,000 gal mixture of solvents and

solids

C All materials added simultaneously

C T = 77°F (537°R)

C VP (toluene) = 0.58 psia

C VP (MEK) = 1.93 psia

C MW (toluene) = 92.1

C MW (MEK) = 72.1

Gas sweep through dispersion

vessels while loading solids

A: Option 2

S=0.774 for toluene

S=0.788 for MEK

(Equation 8.4-32)

C: Option 1

(Equation 8.4-23)

11600 14814 C Average liquid mole fractions are

same as for filling the vessels

C Sweep rate = 10 ft3/min

C Diameter of vessels = 7 ft

C T = 77°F (537°R)

C Sweep time = 1 hr/batch

C 1,500 batches/yr

Heat up in dispersion vessels

due to mixing

A: Option 2 

(Equation 8.4-15)

C: Option 1 

(Equation 8.4-10)

412 417 C Initial T = 77°F (537°R)

C Final T = 105°F (565°R)

C Average liquid mole fractions are

same as for filling the vessels

C VPT2 (toluene) = 1.16 psia

C VPT2 (MEK) = 3.75 psia

C Sum of partial pressure for toluene

and MEK at 105°F = 2.195 psia

Mixing in dispersion vessels

after sweep is turned off

(surface evaporation)

B: K based on gas velocity

(Equations 8.4-21 and 8.4-

22)

2089 C batch time after sweep is turned off =

5 hours

C final temperature has been reached by

the time the gas sweep is turned off

(thus, T = 105°F [565°R])

C gas velocity above the vessel is

determined to be 0.25 mph

C area of annulus in cover around the

agitator shaft = 3 ft2

.
Table 8.3-1. (continued)

Chapter 8 – Paint, Ink, and Other Coating Manufacturing 02/01/05

Emission Event

VOC Emissions, lb/yr

ABC Data and Assumptions

EIIP Volume II 8.3-7

Transfer contents of

dispersion vessels to thindown

tanks

A: Saturation factor = 0.6

B: Saturation factor = 1.0

C: Saturation factor = 1.45

(Equation 8.4-1)

5011 8352 12111 C T = 105°F (565°R)

C quantity transferred = 2,200,000 gal

Add Toluene to thindown

tanks

A: saturation factor = 0.6

B: saturation factor = 1.0

C: saturation factor = 1.45

(Equation 8.4-1)

355 592 859 C T = 77°F (537°R)

C quantity added = 200 gal/batch

Holding/mixing in thindown

tank

B: K based as gas velocity

(Equations 8.4-21 and 8.4-

22)

1048 C hold for 5 hours

C T = 77°F (537°R)

C gas velocity above vessel estimated to

be 0.25 mph

C area of annulus in cover around the

agitator shaft = 3ft2

Product loading

A: saturation factor = 0.6

B: saturation factor = 1.0

C: saturation factor = 1.45

(Equation 8.4-1)

2870 4784 6937 C total volume loaded = 2,500,000

gal/yr

C T = 77°F (537°R)

C sum of partial pressures from VOC’s

at 77°F = 1.0375 psia

Cleaning (solvent flush)

A: saturation factor = 0.6

B: saturation factor = 1.0

C: saturation factor = 1.45

(Equation 8.4-1)

56 93 135 C total amount of solvent used = 75,000

gal/yr

C solvent is toluene

C T = 77°F (537°R)

Small parts cleaning

B: AP-42 emission factor

(Equation 8.5-13)

660 C one open top vapor degreaser

C AP-42 emission factor = 0.33

ton/yr/unit
Table 8.3-1. (continued)

Chapter 8 – Paint, Ink, and Other Coating Manufacturing 02/01/05

Emission Event

VOC Emissions, lb/yr

ABC Data and Assumptions

8.3-8 EIIP Volume II

Solvent reclamation

A: Modeling 

(Equations 8.4-1 and 8.4-

34)

C: AP-42 emission factor

(Equation 8.4-8)

319 990 C 300 tons of waste toluene cleaning

solvent processed annually

C see example 8.4-10

Material storage

B: using TANKS program

6000

Equipment leaks

B: Emission factors in section

5.1.6

949 C 15 valves

C 10 pumps

C 50 connectors

C 8760 hr/yr

C see example 8.5-8

Spills

B: Equation 8.4-19

18 C One MEK spill outdoors

C T = 77°F (537°R)

C Area of spill = 15 ft2

C windspeed at 10 m above the surface

= 8 mph

C cleanup time = 1 hr

Totals 34,070 to 53,512 
Chapter 8 – Paint, Ink, and Other Coating Manufacturing 02/01/05

EIIP Volume II 8.4-1

4.0 Modeling Methods for Estimating Emissions

Models/equations for estimating VOC emissions, including HAP, from paint, ink, and other

coating manufacturing operations are presented in this section. This section describes these

methodologies and provides examples to illustrate the use of each calculation technique. 

Source-specific emission models/equations are presented for estimating VOC emissions from:

# Mixing operations (material loading, heat-up losses, and surface evaporation),

# Product filling,

# Vessel cleaning operations,

# Gas sweep or purge,

# Wastewater treatment processes,

# Solvent reclamation,

# Material storage, and

# Spills. 

Models for these operations are discussed with examples given below. For additional guidance

on estimating emissions from wastewater collection and treatment, see Chapter 5 of this volume. 

See also Chapter 1 of this volume for additional guidance on material storage.

It is not recommended that paint, ink, and other coating manufacturing facilities apply these

models to each of the hundreds or even thousands of different formulations. Rather,

formulations should be grouped based on composition and production rate, and a representative

recipe and composition should be defined for each group. The emission calculations are then

performed for each of the group representatives. In general, there are no specific guidelines for

defining product groups except that each product group composition should be fairly

characteristic of its components (Fisher et al., 1993).

Table 8.4-1 lists the variables used in Equations 8.4-1 through 8.4-27.
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8.4-2 EIIP Volume II

Table 8.4-1. List of Variables and Symbols

Variable Symbol Units

Total VOC emissions EVOC lb/yr

Saturation factor S dimensionless

Vapor pressure of the material loaded P pounds per

square inch

absolute (psia)

Vapor molecular weight M lb/lb-mole

Volume of material loaded Q 1,000 gal/yr

Temperature T °R

Partial vapor pressure of VOC species x Px psia

Liquid mole fraction of VOC species x mx mole/mole

True vapor pressure of VOC species x VPx psia

Henry’s Law constant for VOC species x Hx psia

Liquid mass fraction of VOC species x zx lb/lb

Molecular weight of VOC species x Mx lb/lb-mole

Vapor mole fraction of VOC species x yx mole/mole

Loading emissions of VOC species x Ex lb/yr

Vapor mass fraction of VOC species x xx lb/lb

Initial partial pressure of VOC species x (Px)T1 psia

Final partial pressure of VOC species x (Px)T2 psia

Number of pound-moles of gas displaced )n lb-mole/cycle

Vapor molecular weight, average Ma lb/lb-mole

Number of cycles/year CYC cycles/yr

Volume of free space in vessel V ft3

Universal gas constant at 1 atmosphere of pressure R 10.73 psia- ft3/

°R-lb mole

Initial noncondensable gas partial pressure in vessel Pa1 psia

Final noncondensable gas partial pressure in vessel Pa2 psia

Initial temperature of vessel T1 °R

Final temperature of vessel T2 °R

Moles of VOC species x leaving vessel per batch Nx,out lb-mole
Table 8.4-1. (continued)

Chapter 8 – Paint, Ink, and Other Coating Manufacturing 02/01/05

Variable Symbol Units

EIIP Volume II 8.4-3

Average molar volume in gas space during heating Navg lb-mole

Initial moles of VOC species x in gas space nx,1 lb-mole

Final moles of VOC species x in gas space nx,2 lb-mole

Initial system pressure P1 psia

Final system pressure P2 psia

Initial total moles in gas space n1 lb-mole

Final total moles in gas space n2 lb-mole

Gas-phase mass transfer coefficient for VOC species x Kx ft/sec

Surface area (of spill or tank) A ft2

Duration of spill HR hr/event

Wind speed U mile/hr

Diffusion coefficient for VOC species x in air Dx ft2

/sec

Batch time H hr/batch

Number of batches per year B batches/yr

Flow rate of noncondensable gas into vessel Fnc ft3

/min

Total system pressure PT psia

Flow rate of VOC species x out of vessel at saturated vapor pressure Fx

sat ft3

/min

Partial pressure of VOC species x in a saturated gas stream Px

sat psia

Mass transfer coefficient for a reference compound Ko cm/s

Mass transfer coefficient for VOC species x Kx cm/s

Molecular weight of reference compound Mo lb/lb-mole

Operating Hours OH hr/yr

4.1 Emission Model for Material Loading

VOC emissions resulting from the addition of materials to mixers, grinding equipment, and

thindown tanks may be calculated using a modification of the loading loss equation (which is

presented in Section 5.2 of AP-42; EPA, 1995c). This equation, shown below as Equation 

8.4-1, is related to tank car or tank truck loading, but can be applied to any tank or vessel loading

(NPCA, 1995). This equation may also be applied to estimate product filling losses.
Chapter 8 – Paint, Ink, and Other Coating Manufacturing 02/01/05

8.4-4 EIIP Volume II

(8.4-1)

(8.4-2)

where

EVOC = total VOC loading emissions (lb/yr)

S = saturation factor (dimensionless; see Table 5.2-1 in AP-42)

P = vapor pressure of the material loaded at temperature T (psia)

M = vapor molecular weight (lb/lb-mole)

Q = volume of material loaded (1,000 gal/yr)

T = temperature of liquid loaded (°R).

The constant in equation 8.4-1 is a function of the units used for other variables in the equation. 

The table below shows the constant that would apply if some of the variables are available in

other units.

Constant P M Q T

12.46 psia lb/lb-mole 1,000 gal °R

0.241 mm Hg lb/lb-mole 1,000 gal °R

6.92 psia lb/lb-mole 1,000 gal °K 

Calculation of VOC emissions using Equation 8.4-1 is based on the following assumptions:

# The vapors displaced from the process vessel are identical to the vapors from the

materials being loaded;

# The volume of vapor displaced is equal to the volume of material loaded into the

vessel; and

# All solvent additions are coincident at a constant temperature (in reality, solvent

additions may be phased) (Fisher et al., 1993).

An alternative to using the AP-42 saturation factor when material is added by submerged loading

is to assume the vapor space in the vessel is saturated with the solvent vapors (i.e., equivalent to

S = 1). This assumption is a conservative approach that would ensure that emissions are not

underestimated.

If multiple solvents are used, the vapor pressure (P) will need to be calculated using

Equation 8.4-2:
Chapter 8 – Paint, Ink, and Other Coating Manufacturing 02/01/05

EIIP Volume II 8.4-5

(8.4-3)

(8.4-4)

(8.4-5)

(8.4-6)

where

P = vapor pressure of material loaded (psia)

Px = partial pressure of VOC species x (psia).

Px may be calculated using Raoult’s Law (for ideal solutions) or using Henry’s Law constants

(when gases are dissolved at low concentrations in water). Raoult’s Law is given in

Equation 8.4-3:

where

Px = partial vapor pressure of VOC species x (psia)

mx = liquid mole fraction of VOC species x (mole/mole)

VPx = true vapor pressure of VOC species x (psia).

Px may be calculated using Henry’s Law constants and Equation 8.4-4:

where

Px = partial vapor pressure of VOC species x (psia)

mx = liquid mole fraction of VOC species x (mole/mole)

Hx = Henry’s Law constant for VOC species x.

The liquid mole fraction of VOC species x (mx) may be calculated if the liquid weight fractions

of all species are known. Equation 8.4-5 is used:

where

mx = liquid mole fraction of VOC species x (mole/mole)

zx = liquid mass fraction of VOC species x (lb/lb)

Mx = molecular weight of VOC species x (lb/lb-mole).

The vapor molecular weight (M) will also need to be calculated if multiple solvents are used for a

single cleaning event. Equation 8.4-6 may be used:
Chapter 8 – Paint, Ink, and Other Coating Manufacturing 02/01/05

8.4-6 EIIP Volume II

(8.4-7)

(8.4-8)

(8.4-9)

where

M = vapor molecular weight (lb/lb-mole)

yx = vapor mole fraction of VOC species x (mole/mole)

Mx = molecular weight of VOC species x (lb/lb-mole).

The vapor mole fraction (yx) is calculated using Equation 8.4-7:

where

yx = vapor mole fraction of VOC species x (mole/mole)

Px = partial pressure of VOC species x (calculated using Equation 8.4-3 or

8.4-4) (psia)

P = vapor pressure of the material loaded (calculated using Equation 8.4-2).

Speciated VOC emissions are calculated using Equation 8.4-8:

where

Ex = loading emissions of VOC species x (lb/yr)

EVOC = total VOC loading emissions, calculated using Equation 8.4-1 (lb/yr)

xx = vapor mass fraction of VOC species x (lb/lb).

The vapor mass fraction of VOC species x (xx) is calculated using Equation 8.4-9:

where

xx = vapor mass fraction of VOC species x (lb/lb)

yx = vapor mole fraction of VOC species x, calculated using Equation 8.4-7

(mole/mole)

Mx = molecular weight of VOC species x (lb/lb-mole)

M = vapor molecular weight, calculated using Equation 8.4-6 (lb/lb-mole).
Chapter 8 – Paint, Ink, and Other Coating Manufacturing 02/01/05

EIIP Volume II 8.4-7

Example 8.4-1

A mixing vessel is cleaned with a solvent mixture at the end of each day. The following data are

given:

# The yearly consumption of the solvent mixture (Q) is 600,000 gal;

# The cleaning solvent is a 50/50 mixture (by weight) of toluene and heptane;

# The solvent mixture is splash loaded into the vessel (S = 1.45); and

# The temperature of the solvent is 77°F or 537°R 

(°R = °F + 460).

Example 8.4-1 illustrates the use of the loading equation (Equation 8.4-1) and the supplemental

equations (Equations 8.4-2 through 8.4-9).

Emissions are calculated by following Steps 1 through 8 below.

Step 1: Apply Equation 8.4-5 - Calculation of Liquid Mole Fraction (mx)

Component

Liquid Mass

Fraction, zx

 (lb of x/lb of

liquid)

Molecular

Weight, Mx

(lb of x/lb-mole 

of x)

Liquid Mole Fraction, mx

(mole of x/mole of liquid)

Toluene 0.5 92 zx/Mx = (0.5 / 92) 

G(zx/Mx) [(0.5/92) + (0.5/100)]

 = 0.52

Heptane 0.5 100 zx/Mx = (0.5 / 100) 

G(zx/Mx) [(0.5/92) + (0.5/100)]

 = 0.48
Chapter 8 – Paint, Ink, and Other Coating Manufacturing 02/01/05

8.4-8 EIIP Volume II

Step 2: Apply Equation 8.4-3 - Calculation of Partial Vapor Pressure (Px)

Component

Liquid Mole Fraction, mx

(mole of x/mole 

of liquid)

Vapor

Pressure, VPx

(psia)

Partial Vapor 

Pressure, Px (psia)

Toluene 0.52 0.58 mx × VPx = 0.52 × 0.58

 = 0.30

Heptane 0.48 0.9 mx × VPx = 0.48 × 0.90

 = 0.43

Step 3: Apply Equation 8.4-2 - Calculation of Vapor Pressure (P)

P = GPx

= 0.30 + 0.43

= 0.73 psia

Step 4: Apply Equation 8.4-7 - Calculation of Vapor Mole Fraction (yx)

Component

Partial Vapor

Pressure, Px

(psia)

Total Vapor

Pressure, P

(psia)

Vapor Mole 

Fraction, yx

(mole of x/mole 

of vapor)

Toluene 0.3 0.73 Px = 0.30

P 0.73

 = 0.41

Heptane 0.43 0.73 Px = 0.43

P 0.73

 = 0.59

Step 5: Apply Equation 8.4-6 - Calculation of Vapor Molecular Weight (M)

M = G(yx × Mx)

= (0.41 × 92) + (0.59 × 100)

= 97 lb/lb-mole
Chapter 8 – Paint, Ink, and Other Coating Manufacturing 02/01/05

EIIP Volume II 8.4-9

Step 6: Apply Equation 8.4-9 - Calculation of Vapor Mass Fraction (xx)

Component

Vapor Mole

Fraction, yx

(mole of

x/mole of

vapor)

Molecular

Weight, Mx

(lb of x/lb-mole 

of x)

Vapor Molecular

Weight, M

(lb of vapor/lb-mole

of vapor)

Vapor Mass

Fraction, xx

(lb of x/lb of vapor)

Toluene 0.41 92 97 yx × Mx = 0.41 × 92

 M 97

 = 0.39

Heptane 0.59 100 97 yx × Mx = 0.59 × 100

 M 97

 = 0.61

Step 7: Apply Equation 8.4-1 - Calculate Total VOC Emissions (EVOC)

Step 8: Apply Equation 8.4-8 - Calculate Speciated VOC Emissions (Ex)

Component

VOC Emissions, EVOC

(lb VOCs)

Vapor Mass Fraction, xx

(lb of x/lb of VOCs)

Speciated VOC 

Emissions, Ex (lb x)

Toluene 1,429 0.39 EVOC × xx = 1,429×0.39

 = 557

Heptane 1,429 0.61 EVOC × xx = 1,429 × 0.61

 = 872

4.2 Heat-Up Losses

Heat-up losses that occur during the operation of high-speed dispersers, bead and ball mills, and

similar types of dispersing equipment may be estimated by application of the Ideal Gas Law and

vapor-liquid equilibria principles. Emissions are calculated using the following assumptions:
Chapter 8 – Paint, Ink, and Other Coating Manufacturing 02/01/05

8.4-10 EIIP Volume II

(8.4-10)

# Covers are closed during operation, but it is possible for vapors to be vented during

operation;

# No material is added during heat-up;

# The displaced gas is always saturated with VOC vapor in equilibrium with the liquid

mixture;

# The moles of gas displaced from the vessel result from the expansion of gases during

heat-up and an increase in VOC vapor pressure; and

# The vapor pressure of the mixers never rises above 1 atmosphere (Fisher et al., 1993).

This section presents two equations for estimating heatup emissions. The first is from Control of

Volatile Organic Compound Emissions from Batch Processes (EPA, 1994c). The second was

derived by performing moderate balances around the vessel headspace for the noncondensable

component and for condensable component x during the heating (Hatfield, 1998a).

The two approaches yield similar results when the amount of heat-up is small, and the final

temperature is well below the boiling point of the liquid mixture. However, the disparity

between the results from the two options increases as the final temperature approaches the

boiling point. Under these conditions Option 1 gives unrealistically high estimates, and Option 2

is the better choice. 

4.2.1 Option 1

The equation for calculating heat-up emissions that is in Control of Volatile Organic Compound

Emissions from Batch Processes is shown in Equation 8.4-10 (EPA, 1994c).

where

EVOC = VOC emissions from material heat-up in the process equipment (lb/yr)

(Px)T1 = initial partial pressure of each VOC species x in the vessel headspace at the

initial temperature T1 (psia); see Equations 8.4-3 and 8.4-4

(Px)T2 = final partial pressure of each VOC species x in the vessel headspace at the

final temperature T2 (psia); see Equations 8.4-3 and 8.4-4

)n = number of pound-moles of gas displaced (lb-mole/cycle)

Ma = average vapor molecular weight (lb/lb-mole)

CYC = number of cycles per year (cycles/yr).
Chapter 8 – Paint, Ink, and Other Coating Manufacturing 02/01/05

EIIP Volume II 8.4-11

(8.4-11)

(8.4-12)

(8.4-13)

(8.4-14)

The term )n may be calculated using Equation 8.4-11:

where

)n = number of pound-moles of gas displaced (lb-mole/cycle)

V = volume of free space in the vessel (ft3)

R = universal gas constant at 1 atmosphere of pressure, 

10.73 psia " ft3

/lb-mole " °R

Pa1 = initial gas pressure in vessel (psia)

Pa2 = final gas pressure in vessel (psia)

T1 = initial temperature of vessel (°R)

T2 = final temperature of vessel (°R).

Pa1 and Pa2 may be calculated using Equations 8.4-12 and 8.4-13:

where

Pa1 = initial gas pressure in vessel (psia)

Pa2 = final gas pressure in vessel (psia)

(Px)T1 = partial pressure of each VOCx in the vessel headspace (psia) at the initial

temperature T1; see Equations 8.4-3 and 8.4-4

(Px)T2 = partial pressure of each VOCx in the vessel headspace (psia) at the final

temperature T2; see Equations 8.4-3 and 8.4-4.

Speciated VOC emissions would be calculated using a modified version of Equation 8.4-10 as

shown in Equation 8.4-14:
Chapter 8 – Paint, Ink, and Other Coating Manufacturing 02/01/05

8.4-12 EIIP Volume II

Example 8.4-2

This example shows how heat-up losses from a disperser are calculated using Equations 8.4-10

through 8.4-13. Supporting equations from Section 4.1.1 (Equations 8.4-3 and 8.4-5) are also used

in this example.

A 3,000-gallon, high-speed disperser contains 2,000 gallons of paint. The following data are

given:

# The paint consists of 30 percent by weight toluene, 20 percent by 

weight methyl ethyl ketone (MEK), and 50 percent by weight insoluble pigments and

nonvolatile resins;

# The initial temperature (T1) of the mixture is 77°F or 537°R (°R = 

°F + 460);

# The final temperature (T2) is 105°F (565°R);

# The average vapor molecular weight (Ma) is 77 lb/lb-mole (calculated using Equation 8.4-

6); and

# The mixer goes through the given temperature cycle with this paint formulation 25

times/yr (CYC).

# The volume of free space in the vessel is 3,000 - 2,000 gal = 1,000 gal or 133.68 ft3.

where

Ex = VOC species x emissions from material heat-up in the process equipment

(lb/yr)

(Px)T1 = partial pressure of VOC species x in the vessel headspace at the initial

temperature T1 (psia); see Equations 8.4-3 and 8.4-4

(Px)T2 = partial pressure of VOC species x in the vessel headspace at the final

temperature T2 (psia); see Equations 8.4-3 and 8.4-4

)n = number of pound-moles of gas displaced (lb-mole/cycle); see

Equation 8.4-11

Ma = average vapor molecular weight (lb/lb-mole)

CYC = Number of cycles/year.

Example 8.4-2 illustrates the use of Equations 8.4-10 through 8.4-13. Emissions are calculated

by following Steps 1 through 6 presented on the next few pages.
Chapter 8 – Paint, Ink, and Other Coating Manufacturing 02/01/05

EIIP Volume II 8.4-13

Step 1: Apply Equation 8.4-5, Calculation of Liquid Mole Fraction (mx)

Component x

Liquid Mass

Fraction, zx (lb of

x/lb of liquid)

Molecular Weight, Mx

(lb of x/lb-mole of x)

Liquid Mole Fraction, mx

 (mole of x/mole of liquid)

 Toluene 0.3 92 zx/Mx = 0.3/92 

G(zx/Mx) (0.3/92 + 0.2/72)

= 0.54

 MEK 0.2 72 zx/Mx = 0.2/72 

G(zx/Mx) (0.3/92 + 0.2.72)

= 0.46

Step 2: Apply Equation 8.4-3, Calculation of Partial Vapor Pressure at Initial

Temperature [(Px)T1]

Component x

Liquid Mole

Fraction, mx (mole of

x/mole of liquid)

Vapor Pressure, VPx

@ 77°F (psia)

Partial Pressure at T1, 

(Px)T1 (psia)

Toluene 0.54 0.58 mx × VPx = 0.54 × 0.58

 = 0.313

MEK 0.46 1.93 mx × VPx = 0.46 × 1.93

 = 0.888

Step 3: Apply Equation 8.4-3, Calculation of Partial Pressure at Final Temperature [(Px)T2]

Component x

Liquid Mole Fraction,

mx (mole/mole)

Vapor Pressure, 

VPx @ 105°F

(psia)

Partial Pressure at T2, 

(Px)T2 (psia)

Toluene 0.54 1.16 mx × VPx = 0.54 × 1.16

 = 0.626

MEK 0.46 3.75 mx × VPx = 0.46 × 3.75

 = 1.73
Chapter 8 – Paint, Ink, and Other Coating Manufacturing 02/01/05

8.4-14 EIIP Volume II

Step 4: Apply Equations 8.4-12 and 8.4-13, Calculation of Initial Pressure (Pa1) and Final

Pressure (Pa2)

Pa1 = 14.7 - E(Px)T1

= 14.7 - (0.313 + 0.888)

= 13.5 psia

Pa2 = 14.7 - E(Px)T2

= 14.7 - (0.626 + 1.73)

= 12.34 psia

Step 5: Apply Equation 8.4-11, Calculation of lb-moles Gas Displaced ()n)

The volume of free space in the vessel (V) is 3,000 gal - 2,000 gal = 1,000 gal or 133.68 ft3

.

Step 6: Apply Equation 8.4-10, Calculation of Total VOC Emissions (EVOC)
Chapter 8 – Paint, Ink, and Other Coating Manufacturing 02/01/05

EIIP Volume II 8.4-15

Step 7: Apply Equation 8.4-14, Calculation of Toluene Emissions (EVOC)

4.2.2 Option 2

In this heating model, rising vapors from the vessel liquid contents displace the noncondensable

gas components from the headspace through the process vessel vent. As the liquid mixture

reaches the boiling point, all of the noncondensable component is purged from the vapor space. 

This model assumes that the average molar headspace volume remains constant relative to

changes in the molar composition of the vessel headspace. Equation 8.4-15 is derived from

performing material balances around the vessel headspace for the noncodensable component and

for condensable component x during the heating (Hatfield, 1998a).

N N ln ( ) (8.4-15)

Pa

Pa

n n x,out avg

1

2

x,2 x,1 vessel = ⎛

⎝

⎜

⎜

⎞

⎠

⎟

⎟ − −

where

Nx,out = moles of volatile component x leaving the vessel per batch

Navg = average gas space molar volume during the heating process

Pa1 = partial pressure of noncondensable in the vessel headspace at initial

temperature

Pa2 = partial pressure of noncondensable in the vessel headspace at final

temperature

nx,2 = moles of volatile component x in the vessel headspace at the final

temperature

nx,1 = moles of volatile component x in the vessel headspace at the initial

temperature.

Note that when the liquid in the vessel contains more than one volatile component, Equation 8.4-

15 estimates the total moles of volatile components emitted, and nx,1 and nx,2 are the total moles

of all volatile components in the vessel headspace.
Chapter 8 – Paint, Ink, and Other Coating Manufacturing 02/01/05

8.4-16 EIIP Volume II

The term Navg may be calculated using equation 8.4-16:

where

n1 = total moles of gas in the vessel headspace at the initial temperature

n2 = total moles of gas in the vessel headspace at the final temperature.

The total number of moles (n1 and n2) may be calculated using the ideal gas law as shown in

equation 8.4-17 and 8.4-18.

n 

P V

RT

n 

P V

RT

1

1

1

2

2

2

=

=

(8.4-17)

(8.4-18)

where

P1 = total system pressure at initial temperature

P2 = total system pressure at final temperature

V = volume of gas space in the vessel

R = gas constant

T1 = initial temperature of vessel contents

T2 = final temperature of vessel contents.

The total number of moles of volatile component x in the vessel headspace at the initial and final

temperatures (nx,1 and nx,2) are also calculated using equations 8.4-17 and 8.4-18, except the

partial pressures of the volatile component are used instead of the total system pressure.

N ( ) 1

2 avg 1 2 = + n n ( 8.4-16)

Example 8.4-3

For the same disperser described in example 8.4-2, what heat-up emissions would be estimated using

option 2?
Chapter 8 – Paint, Ink, and Other Coating Manufacturing 02/01/05

EIIP Volume II 8.4-17

Step 1: Apply Equations 8.4-17 and 8.4-18, Determine Total Moles in the Vessel Headspace

at Initial and Final Temperatures

( )( )

( )

( )( )

( )

n 

P V

RT 14.7 psia 133.68 ft

10.73 ft psia

lbmole R 537 R

 0.341 lbmole

n 

P V

RT 14.7 psia 133.68 ft

10.73 ft psia

lbmole R 565 R

 0.324 lbmole

1 

1

1

3

3

2

2

2

3

3

= =

°

⎛

⎝

⎜ ⎞

⎠

⎟ °

=

= =

°

⎛

⎝

⎜ ⎞

⎠

⎟ °

=

Step 2: Apply Equation 8.4-16, Determine Navg

N ( ) ( ) 1

2

 n n 

1

2

 0.341 0.324 0.333 lbmole avg 1 2 = += + =

Step 3: Apply Equations 8.4-12 and 8.4-13, Calculation of Noncondensable Partial

Pressures and Initial and Final Temperatures

These calculations are shown in Step 4 of example 8.4-2.

Pa 13.5 psia

Pa 12.34 psia

1

2

=

=

Step 4: Determine Partial Pressures of Volatile Components

These values were determined in Steps 2 and 3 of example 8.4-2:

Component x (Px)T1, psia (Px)T2, psia

Toluene 0.313 0.626

MEK 0.888 1.73
Chapter 8 – Paint, Ink, and Other Coating Manufacturing 02/01/05

8.4-18 EIIP Volume II

Step 5: Apply Equations 8.4-17 and 8.4-18, Determine Moles of Condensable Compounds

in the Vessel Headspace at Initial and Final Temperatures

( )( ) ( )( )

( )

( )( ) ( )( )

( )

n 

(P ) V

RT 0.313 0.888 psia 133.68 ft

10.73 ft psia

lbmole R

 537 R

 0.0279 lbmole

n 

(P ) V

RT 0.626 1.73 psia 133.68 ft

10.73 ft psia

lbmole R

 565 R

 0.0520 lbmole

x,1

x T1

1

3

3

x,2 

x T2

2

3

3 

= = +

⎛

⎝

⎜ ⎞

⎠

⎟

=

= = +

⎛

⎝

⎜ ⎞

⎠

⎟

=

Σ

Σ

o

o

o

o

Step 6: Apply Equation 8.4-15, Calculate Total Moles of VOC Emissions

( )

( ) ( )

n N ln 

Pa

Pa

 n n

 0.333 ln 

13.5

12.34 0.0520 0.0279

 0.00582 lbmole VOC / batch

x,out avg

1

2

x,2 x,1 vessel = ⎛

⎝

⎜ ⎞

⎠

⎟ − −

= ⎛

⎝

⎜ ⎞

⎠

⎟ − −

=

Using the average vapor molecular weight from example 8.4-2, the total mass of VOC emitted

per batch is:

E 0.00582 lbmole

batch

77 lb

lbmole

0.448 lb batch VOC = ⎛

⎝

⎜ ⎞

⎠

⎟

⎛

⎝

⎜ ⎞

⎠

⎟ =

For 25 batches per year, the annual emissions are:

E 0.448 lb batch 25 batches yr 11.2 lb yr VOC = = ( )( )

This estimate is essentially the same as the emissions estimated using option 1 in example 

8.4-2.
Chapter 8 – Paint, Ink, and Other Coating Manufacturing 02/01/05

1

 The vapor pressures of VOC species are listed in AP-42 on Table 7.1-3 (EPA, 1997b). The partial

pressure of VOC species x (Px) may be calculated using Equation 8.4-3 or Equation 8.4-4.

EIIP Volume II 8.4-19

(8.4-19)

Step 7: Determine the Amount of Each Volatile Species in the Total VOC Emissions

Compound

Average

Partial

Pressure,

psia

Average Vapor

Phase Mole

Fraction

Number of

lbmole

Emitted

Molecular 

Weight

Mass Emission

lb/batch lb/yr

Toluene 0.47 0.26 0.0015 92 0.138 3.45

MEK 1.31 0.74 0.0043 72 0.31 7.74

Totals 1.78 0.0058 0.448 11.2

4.3 Emission Model for Spills

The evaporation rate and VOC emissions that result from a liquid chemical spill can be estimated

using a simple model if the size (area) of the spill is known or can be estimated. Other more

complex spill models are also available, but they may require more input data (EPA, 1987). 

Equation 8.4-19, used for the simple model, is as follows:

where

Ex = emissions of VOC species x from the spill (lb/event)

Mx = molecular weight of VOC species x (lb/lb-mole)

Kx = gas-phase mass transfer coefficient for VOC species x (ft/sec)

A = surface area of spill (ft2

)

Px = vapor pressure of VOC species x (if a pure chemical is spilled) or the

partial pressure of chemical x (if a mixture of VOCs is spilled) at

temperature T (psia)1

3600 = 3600 sec/hr

HR = duration of spill (hr/event)

R = universal gas constant at 1 atmosphere of pressure, 

10.73 psia-ft3

/°R- lb-mole

T = temperature of the liquid spilled, °R (°F + 460).
Chapter 8 – Paint, Ink, and Other Coating Manufacturing 02/01/05

8.4-20 EIIP Volume II

(8.4-20)

(8.4-21)

The gas-phase mass transfer coefficient (Kx) may be calculated using Equation 8.4-20:

where

Kx = gas-phase mass transfer coefficient for VOC species x (ft/sec)

U = wind speed (mile/hr)

Dx = diffusion coefficient for VOC species x in air (ft2

/sec).

Diffusion coefficients (Dx) can be found in chemical handbooks and are usually expressed in

units of square centimeters per second (cm2

/sec). If a diffusion coefficient is not available for a

particular chemical, the gas-phase mass transfer coefficient (Kx) may be estimated using

Equation 8.4-21:

where

Kx = gas-phase mass transfer coefficient for VOC species x (ft/sec)

U = wind speed (mile/hr)

Mx = molecular weight of VOC species x (lb/lb-mole).

Equations 8.4-20 and 8.4-21 and other similar correlations that are used in more complex models

were developed to estimate evaporation from liquid surfaces exposed to natural wind effects. 

The standard practice when using these equations is that the wind speed is the value at a height

10 meters above the surface (EPA, 1994a). Thus, the equations should be acceptable for

estimating mass transfer coefficients for spills that are outdoors. If the spill is indoors, however,

the equation should be used with caution. The wind profile inside a building likely differs from

the profile outside, so the velocity at a height of 10 meters (even if that much open space exists

above the spill) will not have the same meaning as it would outdoors. At a minimum, when

applying the equation to a spill indoors, the user should develop site-specific estimates of the air

velocity above the spill and recognize the potential that using this approach may underestimate

the emissions. An alternative approach for estimating gas-phase mass transfer coefficients is

discussed in Section 4.5 of this chapter. The alternative replaces the windspeed variable with a

constant reference mass transfer coefficient. This approach likely overstates the emissions,

particularly in a room with little air movement, because it assumes the gas above the liquid is

well mixed. Thus, equation 8.4-21 generally is preferable to the alternative for estimating

emissions from spills and other surface evaporation scenarios.
Chapter 8 – Paint, Ink, and Other Coating Manufacturing 02/01/05

EIIP Volume II 8.4-21

Example 8.4-4

Methyl ethyl ketone (MEK) is spilled onto the ground outside of a building. The following data

are given:

# The spill is not detected for 1 hour; it takes an additional 2 hours to recover the remaining

MEK; the duration of the spill (HR), therefore, is 3 hours.

# The average wind speed (U) is 8 mile/hr.

# The ambient temperature (T) is 77°F or 537°R (°R = °F +460).

# The surface area of the spill (A) is 100 ft2.

# The molecular weight of MEK (Mx) is 72.10 lb/lb-mole.

# The vapor pressure of MEK (Px) at 77°F is approximately 1.93 psia.

Example 8.4-4 illustrates the use of equations 8.4-19 and 8.4-21.

Step 1: Using Equation 8.4-21, calculate the Gas-phase Mass Transfer Coefficient (Kx)

Step 2: Using Equation 8.4-19, Calculate Emissions (Ex)
Chapter 8 – Paint, Ink, and Other Coating Manufacturing 02/01/05

2

 The partial pressure of VOC species x (Px) may be calculated using Equation 8.4-3 or Equation 8.4-4.

8.4-22 EIIP Volume II

(8.4-22)

4.4 Emission Model for Surface Evaporation

Emissions from surface evaporation of VOCs from open or partially covered mixing tanks during

coating mixing operations can be estimated using Equation 8.4-22, which is also based on the

simple vaporization model for spills.

where

Ex = emissions of VOC species x (lb/yr)

Mx = molecular weight of VOC species x (lb/lb-mole)

Kx = gas-phase mass transfer coefficient for VOC species x (ft/sec)

A = surface area of exposure or opening of tank (ft2)

Px = true vapor pressure of VOC x (if a pure chemical is used) or the partial

pressure of chemical x (if a mixture of VOCs is used) at temperature T

(psia)2

3600 = 3600 sec/hr

H = batch time (hr/batch)

R = universal gas constant at 1 atmosphere of pressure,

10.73 psia-ft3/°R-lb mole;

T = temperature of the liquid, °R (°F+460)

B = number of batches per year (batches/yr).

Equations 8.4-20 or 8.4-21 can be used to estimate Kx. Total VOC emissions would equal the

sum of all VOC species emissions. Note that using these equations to estimate mass transfer

coefficients for VOC in a tank inside a building is subject to the same uncertainty discussed in

Section 4.3 for spills inside a building because such applications differ from the situation for

which the equation was developed.
Chapter 8 – Paint, Ink, and Other Coating Manufacturing 02/01/05

EIIP Volume II 8.4-23

Example 8.4-5

A covered tank is used to mix toluene and various insoluble materials. What are the toluene

emissions due to surface evaporation? The following data are given:

# Toluene is the only compound that is a liquid

# The batch time (H) is 4 hours.

# The number of batches per year (B) is 550.

# The average air velocity through the building above the tank (U) is 0.1 miles/hr.

# The ambient temperature (T) is 77°F or 537°R (°R = °F + 460).

# The opening in the cover of the mixing tank (A) for the agitator shaft is 4 ft2.

# The molecular weight of toluene (Mx) is 92 lb/lb-mole.

# The partial vapor pressure of toluene (Px) at 77°F is approximately 0.55 psia.

Examples 8.4-5 and 8.4-6 illustrate the use of Equation 8.4-22. 

Step 1: Using Equation 8.4-21, calculate the Gas-phase Mass Transfer Coefficient (Kx)
Chapter 8 – Paint, Ink, and Other Coating Manufacturing 02/01/05

8.4-24 EIIP Volume II

Step 2: Using Equation 8.4-22, calculate annual emissions (Ex)

Example 8.4-6

An ink manufacturer uses a three roll mill to ensure that the finished ink product meets particle size

and uniformity standards. Material is fed to the rollers between the feed and center rolls. Material is

then transferred from the center roll to the apron roll where it is removed by a stationary knife blade. 

What are the emissions due to surface evaporation? The following data are given:

# The roller elements are 14 inches in diameter and 30 inches long;

# The printing ink being processed contains a light petroleum distillate oil with a molecular

weight of 254;

# The rollers operate at ambient temperature of 77°F;

# The MSDS shows that the vapor pressure for the light petroleum distillate oil at 77°F is

0.097 psia;

# The mole fraction of petroleum distillate oil in the ink mixture is estimated to be 0.3;

# Each batch takes 1.5 hours; and

# 400 batches are processed annually.
Chapter 8 – Paint, Ink, and Other Coating Manufacturing 02/01/05

EIIP Volume II 8.4-25

Step 1: Determine Liquid Surface Area on the Rollers

For this illustration, it is assumed that liquid covers the entire surface area of each roller.

( )

 A d L N

 14 30 3

 3,956 in 27.5 ft

rollers

2 2

= ×××

= ×××

=

π

π

Step 2: Apply Equation 8.4-3, Determine Partial Pressure of Light Petroleum Distillate Oil

P m VP

0.3 0.097

0.0291 psia

x xx = ×

= ×

=

Step 3: Apply Equation 8.4-29, Determine Mass Transfer Coefficient

Note that this example illustrates use of the alternative procedure described in Section 4.5. 

Equation 8.4-21 may be used if a site-specific estimate of air velocity over the rollers can be

estimated.

( )

K

M x

x

= ×

⎛

⎝

⎜ ⎞

⎠

⎟

= ×

⎛

⎝

⎜ ⎞

⎠

⎟

=

083

18

083

18

254

1

3

1

3

.

.

 0.343 cm s 0.0113 ft s
Chapter 8 – Paint, Ink, and Other Coating Manufacturing 02/01/05

8.4-26 EIIP Volume II

Step 4: Apply Equation 8.4-22, Calculate Annual Emissions

E 

M K A P 3600 H

R T

 B

 254 0.0113 7.5 0.0291 3600 1.5

10.73 537 400

 861 lb / yr

x

xx x = × ×× × ×

×

×

= × ×× × ×

×

×

=

4.5 Gas Sweep or Purge

This section presents two models for estimating emissions from a gas sweep or purge through a

partially filled process vessel. The first model (option 1) is from Control of Volatile Organic

Emissions from Batch Processes (EPA, 1994c). The second model (option 2) is a modified

version of the first model in that it includes a procedure based on site-specific conditions for

estimating the degree to which the exhaust gas is saturated with organic compounds (Hatfield,

2003). Note that option 2 is recommended only for applications where the headspace exchange

rate is less than 5 per minute because available data suggest it may underestimate emissions at

higher exchange rates (Watson, 2004).

Applying the surface evaporation model to estimate emissions from a gas sweep or purge is

inappropriate. As noted in section 4.3, the wind speed correlation for estimating the mass

transfer coefficient was developed for scenarios where the flow is uniform across a relatively

quiescent liquid surface, and the wind speed is taken at 10 meters above the surface. Flow inside

a tank is not uniform, sweep air may be impinging on the liquid surface, the liquid surface is

likely turbulent from agitation, material added while loading the vessel may be dropped on the

liquid surface causing splashes, and the wind speed cannot be determined at 10 meters above the

surface. Furthermore, even if the general correlation is still valid under these conditions, the gas

velocity is not uniform across the surface of the liquid, and there is no consensus regarding the

value to use or the point at which the velocity should be determined for use in the correlation.

4.5.1 Option 1

The equation for calculating gas sweep or purge emissions that is in Control of Volatile Organic

Compound Emission from Batch Processes is shown in Equation 8.4-23 (EPA, 1994c).

E (8.4-23) P F M 60 OH

R T

P

P P x

x nc x T

T x

= × × ××

×

×

− Σ
Chapter 8 – Paint, Ink, and Other Coating Manufacturing 02/01/05

EIIP Volume II 8.4-27

where

Ex = emissions of VOC species x, lb/yr

Px = partial pressure of VOC species x, psia

Fnc = flow rate into the vessel, ft3/min

Mx = molecular weight of VOC species x, lb/lbmole

60 = 60 min/hr

OH = hours that the gas sweep or purge operates, hr/yr

R = universal gas constant (10.73 psia ft3

/lbmole °R)

T = temperature of the exhaust gas, °R

PT = total system pressure, psia.

Note that to use this model, the exhaust gas stream is assumed to be in equilibrium with the

liquid if the flow rate into the vessel is less than 100 ft3

/min (i.e., the partial pressure is equal to

the vapor pressure for a tank with one compound in the liquid phase). The exhaust stream is

assumed to be 25 percent saturated if the flow is greater than 100 ft3

/min.

Example 8.4-7 illustrates the use of Equation 8.4-23.

Example 8.4-7

A gas sweep is operated while material is added to a high-speed disperser. What are the annual VOC

emissions during purges? The following data are provided:

# The average composition of the material in the high-speed disperser while the sweep

operates is 30% by weight toluene, 20% by weight MEK, and 50% by weight insoluble

pigments and nonvolatile resins;

# The temperature of the material in the vessel and the exhaust gas is 77°F (537°R);

# The partial pressures of toluene and MEK at 77°F are 0.313 psia and 0.888 psia, respectively

(see Example 8.4-2, Step 2);

# The inlet purge flow rate is 5 ft3/min;

# The molecular weight of toluene is 92.1 lb/lbmole;

# The molecular weight of MEK is 72.1 lb/lbmole; and

# The purge operates for 1,000 hr/yr.
Chapter 8 – Paint, Ink, and Other Coating Manufacturing 02/01/05

8.4-28 EIIP Volume II

Step 1: Apply Equation 8.4-23 to Calculate Toluene Emissions

Note that since te purge flow is <100 ft3/min, the exhaust gas stream is assumed to be saturated

with toluene and MEK.

( )

E P F M 60 OH

R T PP P

 0.313 5 92.1 60 1,000

10.73 537 14.7

14.7 0.313 0.888

 1,634 lb yr

x

x nc x T

T x

= × × ××

×

× −

= ×× × ×

×

×

− +

=

Σ

Step 2: Apply Equation 8.4-23 to calculate MEK Emissions

( ) E 0.888 5 72.1 60 1,000

10.73 537

14.7

14.7 0.313 0.888

 3,630 lb / yr

x = ×× × ×

×

×

− +

=

Step 3: Sum the Emissions from Steps 1 and 2

E 1,634 3,630

 5,264 lb / yr

VOC = +

=

4.5.2 Option 2

This model is the same as the model in Option 1 except that it adds a site-specific saturation

factor for each VOC species in the exit gas stream. Equation 8.4-24 is used to calculate the

saturation factor.

S 

P

P K A

F KA K A

KA F SF x

x

x

Sat

x

x

x

x nc x x

Sat = = + = + + (8.4-24)

where

Sx = saturation factor for VOC species x

Kx = mass transfer coefficient for VOC species x

A = surface area of the liquid

Fnc = volumetric flow rate of the noncondensable purge (e.g., air, nitrogen)

Fx

Sat = volumetric flow rate of VOC species x at the saturated partial pressure.
Chapter 8 – Paint, Ink, and Other Coating Manufacturing 02/01/05

EIIP Volume II 8.4-29

Equation 8.4-24 was developed based on the following relationships and assumptions. 

Equation 8.4-25 relates the evaporation rate for a VOC species x within a vessel to its molecular

weight, mass transfer coefficient, surface area, and other known variables [Crowl & Louvar,

2002].

E ( ) MKA

RT m P P x x

x

Sat = − x (8.4-25)

where

Em = evaporation rate (lb/min)

Mx = molecular weight of VOC species x

Kx = mass transfer coefficient (ft/min)

A = surface area (ft2

)

R = ideal gas constant

T = temperature of liquid

Px

Sat = partial pressure of VOC species x in a saturated gas stream (true vapor

pressure if the liquid is pure species x)

Px = actual partial pressure of VOC species x next to the liquid surface.

Equation 8.4-26 is the basic equation for calculating the emission rate for VOC species x from a

gas sweep or purge operation based on the exit gas flow rate, partial pressure of VOC species x,

molecular weight, and other known variables.

E (8.4-26) FP

RT

P

P

M

M FP

RT v

T x

T

x

x x = =

where

Ev = emissions from vessel vent (lb/min)

F = exit gas flow rate (ft3

/min)

PT = overall system pressure

R = ideal gas constant

T = temperature of liquid

Px = actual partial pressure of VOC species x

M = molecular weight of VOC species x.

For a vessel at steady state conditions, the emission rate from the gas sweep activity is equal to

the evaporation rate of VOC species x from the liquid within the vessel [Hatfield, 2003]. These

two equations can be set equal and solved for the saturation level Sx (i.e., Px/Px

Sat), resulting in

Equation 8.4-24.
Chapter 8 – Paint, Ink, and Other Coating Manufacturing 02/01/05

8.4-30 EIIP Volume II

Calculation of VOC emissions using Equation 8.4-24 is based on the following assumptions:

# The vessel is at steady state so that the evaporation reate equals the discharge rate in

the exit gas stream.

# The vapor space is perfectly mixed so that once the VOC evaporates there is no

additional resistence to mass transfer to the exit gas stream (this means the reference

mass transfer coefficient, as discussed below, is also assumed to be for a perfectly

mixed system).

.

# The equation is recommended only for headspace exchange rates up to 5 per minute.

The ratio of the mass transfer coefficients between the compound of interest (Kx) and the

reference compound (Ko) is expressed using Equation 8.4-27 (Crowl and Louvar, 2002): 

K

K DD

x

o

x

o

2

3

= ⎛

⎝

⎜ ⎞

⎠

⎟ (8.4-27)

where

Kx = mass transfer coefficient for VOC species x

Ko = mass transfer coefficient for a reference compound

Dx = diffusion coefficient for VOC species x in air

Do = diffusion coefficient for a reference compound in air.

The gas-phase diffusion coefficient D for a compound is estimated from the ratio of the

molecular weight of the compound of interest and a known compound (normally water) using

Equation 8.4-28:

D

D MM

x

o

o

x

1

2

= ⎛

⎝

⎜ ⎞

⎠

⎟ (8.4-28)

where

Mo = molecular weight of a reference compound

Mx = molecular weight of VOC species x.

Combining Equations 8.4-27 and 8.4-28 results in a relationship that can be used to estimate the

mass transfer coefficient of a given volatile compound:
Chapter 8 – Paint, Ink, and Other Coating Manufacturing 02/01/05

EIIP Volume II 8.4-31

K K (8.4-29) M

M x o

o

x

1

3

= ⎛

⎝

⎜ ⎞

⎠

⎟

Water is commonly used as a base reference for estimating the mass transfer coefficient for many

compounds of interest. The mass transfer coefficient of water at 77°F and 14.7 psia is 0.83 cm/s

(0.0272 ft/s) (Matthiesen, 1986).

The saturated partial volumetric flow rate of VOC species x can be estimated from the saturated

partial pressure of the VOC species x, the inlet gas purge rate, and the partial pressure of the noncondensable gas at saturated conditions using Equation 8.4-30:

F F 

P

P P x

Sat 

nc

x

Sat

T x

= × Sat − Σ (8.4-30)

where

Fx

Sat = volumetric flow rate of VOC species x at the saturated partial pressure

Fnc = volumetric flow rate of the noncondensable gas (i.e., air, nitrogen)

Px

Sat = partial pressure of VOC species x in a saturated gas stream (true vapor

pressure if the liquid is pure species x)

PT = total system pressure.

The saturation factor (Sx) may be solved using the standard quadratic solution. Although the

standard quadratic equation contains two roots, only the one solution shown in Equation 8.4-31

produces a realistic value since Sx must be a positive number between 0 and 1.0.

( )( ) S 

 K A F K A F 4F K A

2 F x

x nc x nc

2

x

Sat

x

x

Sat =

− ++ + + (8.4-31)

Finally, the emission rate for VOC species x may be calculated using Equation 8.4-32, which is

similar to Equation 8.4-23, except that the saturated partial pressure is multiplied by the

saturation factor.

E 

M S P F 60 OH

R T P

P P x

xxx

Sat

nc T

T x

= Sat

×× × ××

×

×

− Σ (8.4-32)

For multi-component liquid mixtures, Equation 8.4-24 may be expanded to include partial

volumetric flow rates for each VOC species in the liquid, as shown in Equation 8.4-33:
Chapter 8 – Paint, Ink, and Other Coating Manufacturing 02/01/05

8.4-32 EIIP Volume II

S (8.4-33) K A

KA F SF SF S F

x 1 x

x nc x x

Sat

j j

Sat

n n

Sat + = + + + ++ K

In equation 8.4-33, the subscript x identifies the VOC species for which the saturation level is

being calculated, and terms j through n represent the other VOC species in the liquid. Equation

8.4-33 is solved in an iterative trial and error manner with the initial value of S for each VOC

species assigned to 1.0. The value of S that is calculated for each VOC species is then used as

the starting point for the next iteration. Finally, when the saturation level S of each VOC species

remains the same for subsequent iterations, the calculation process is stopped.

Examples 8.4-8 and 8.4-9 illustrate the use of Equations 8.4-29 through 8.4-33 to estimate

emissions from purging a partially filled vessel.

Step 1: Apply Equation 8.4-29, Estimate Mass Transfer Coefficient

Using water as the reference compound results in the following equation:

( )

K 0.83

18

M

 0.83

18

145

 0.414 cm / s 0.815 ft / min

x 

x

1

3

1

3

= ×

⎛

⎝

⎜ ⎞

⎠

⎟

= ×

⎛

⎝

⎜ ⎞

⎠

⎟

=

Example 8.4-8

A high-speed disperser operates with a gas sweep while material is added to the vessel. What are the

annual VOC emissions? The following data are given:

# Mineral spirits are the only material in the liquid phase;

# The molecular weight of mineral spirits is 145 lb/lbmole;

# The contents of the vessel and the purge are at a temperature of 77°F (537°R);

# Vapor pressure of mineral spirits at 77°F is 0.0032 psia;

# The gas sweep is 5 acfm;

# The diameter of the tank is 5 ft; and

# The gas sweep operates for 1,000 hr/yr.
Chapter 8 – Paint, Ink, and Other Coating Manufacturing 02/01/05

EIIP Volume II 8.4-33

Step 2: Determine Surface Area of Liquid in the Tank

( ) A 

d

4 54

 19.6 ft

2 2

2

= × = ×

=

π π

Step 3: Apply Equation 8.4-30, Determine Saturated Partial Volumetric Flow Rate of

Mineral Spirits in Exit Gas Stream

F F 

P

P P

 5 

0.0032

14.7 0.0032

 0.00109 ft min

x

Sat

nc

x

Sat

T x

Sat

3

= × −

= × −

=

Σ

Step 4: Apply Equation 8.4-31, Calculate Saturation Factor For Mineral Spirits in the Exit

Gas Stream

( )( ) ( )

( ) ( )( ) ( ) ( ) ( )( ) ( )( )( )( )

( )( )

S 

K A F K A F 4F K A

2 F

 

0.815 19.6 5 0.815 19.6 + 5 4 0.00109 0.815 19.6

2 0.00109

 20.974 439.909 0.06965

0.00218

 0.76

x

x nc x nc

2

x

Sat

x

x

Sat

2

=

− ++ + +

=

− ++ +

= −+ +

=

Step 5: Apply Equation 8.4-32, Calculate Annual Emissions

E 

M S P F 60 OH

R T P

P P

 145 0.76 0.0032 5 60 1,000

10.73 537 14.7

14.7 0.0032

 18 lb yr

x

xxx

Sat

nc T

T x

= Sat

×× × ××

×

× −

= × × ×× ×

×

× −

=

Σ
Chapter 8 – Paint, Ink, and Other Coating Manufacturing 02/01/05

8.4-34 EIIP Volume II

Step 1. Apply Equation 8.4-29, Estimate Mass Transfer Coefficients for Toluene and MEK

For toluene:

K 0.83 ( ) 18

92.1

0.482 cm s 0.948 ft min x

1

3

= × ⎛

⎝

⎜ ⎞

⎠

⎟ =

For MEK:

K 0.83 ( ) 18

72.1

0.523 cm s 1.029 ft min x

1

3

= × ⎛

⎝

⎜ ⎞

⎠

⎟ =

Step 2: Determine Surface Area of Liquid in the Tank

( ) A 

d

4 54 19.6 ft

2 2

2 = × = × = π π

Step 3: Determine Saturated Partial Pressures of VOC Species

See Example 8.4-2, Step 2 for the calculations of the following:

VOC VP at 77°F, psia Liquid Mole Fractions Px

Sat, psia

Toluene 0.58 0.54 0.313

MEK 1.93 0.46 0.888

Step 4: Apply Equation 8.4-30, Determine Saturated Partial Volumetric Flowrate of Each

VOC Species

Example 8.4-9

Determine the annual emissions from purging the high-speed disperser in example 8.4-7 using

Option 2. The following additional information is provided:

The diameter of the tank is 5 ft.
Chapter 8 – Paint, Ink, and Other Coating Manufacturing 02/01/05

EIIP Volume II 8.4-35

( ) ( )

( ) ( )

F F

P

P P

F for toluene 5

0.313

14.7 0.313 0.888

0.1160 ft min

F for MEK 5

0.888

14.7 0.313 0.888

0.3288 ft min

x

Sat

nc

x

Sat

T x

Sat

x

Sat

3

x

Sat

3

= × −

= ×

− +

=

= ×

− +

=

Σ

Step 5. Apply Equation 8.4-33, Calculate the Saturation Factors for Each VOC Species

Using trial and error, the following results are obtained:

VOC KxA

Fx

Sat,

ft3

/min

Sx

(iteration 0)

Sx

(iteration 1)

Sx

(iteration 2)

Sx

(iteration 3)

Toluene 18.617 0.116 1 0.77372 0.77682 0.77678

MEK 20.200 0.3288 1 0.78769 0.79065 0.79061

For example, the Sx (iteration 1) for toluene is calculated as follows:

( )( ) ( )( )

 S

K A

KA F SF SF

 

18.617

18.617 5 1 0.116 1 0.3288

0.77372

x

x

x nc x x

Sat

j j

Sat = ++ +

= ++ +

=
Chapter 8 – Paint, Ink, and Other Coating Manufacturing 02/01/05

8.4-36 EIIP Volume II

Step 6: Apply Equation 8.4-32, Calculate Annual Emissions

Step 7: Sum Emissions From Step 6

E 1,270 2,871

4,141 lb yr

VOC = +

=

4.6 Solvent Reclamation

After being collected from coating manufacturing operations, waste cleaning solvents may be

purified and reused. Distillation is one of the most common methods of purifying a solvent. 

Many forms of distillation are used including batch, simple continuous, or steam distillation.

A batch distillation process consists of at least four separate activities including: (1) charging

waste solvent into the still, (2) heating the batch to its boiling point, (3) collecting the distillate in

a receiver, and (4) filling a container or vessel with the collected distillate for storage. Steps 1, 3

and 4 can be modeled using the filling model described earlier in this section (Equation 8.4-1).

Emissions from heating to boiling (Step 2) cannot be modeled using either of the equations for

heatup described in Section 4.2 of this chapter because the equations are mathematically invalid

when the partial pressure of air is zero. However, the emissions can be estimated using

Equation 8.4-34.

(8.4-34) ( ) E

Px

Pa VOC

o n M

l

= ×× ∆ x

( )

( )

 E 

M S P F 60 OH

R T P

P P

 E (toluene) 

92.1 0.777 0.313 5 60 1000

10.73 537 14.7

14.7 0.313 0.888

 1,270 lb / yr

 E (MEK) 

72.1 0.791 0.888 5 60 1000

10.73 537 14.7

14.7 0.313 0.888

 2,871 lb / yr

x

xxx

Sat

nc T

T x

Sat

x

x

= ×× × ××

×

× −

= × × ×× ×

×

×

− +

=

= × × ×× ×

×

×

− +

=

Σ
Chapter 8 – Paint, Ink, and Other Coating Manufacturing 02/01/05

EIIP Volume II 8.4-37

where

(Px)o = partial pressure of VOC species x at the condenser outlet temperature (also

the vapor pressure of the pure compound because only one compound is

condensing)

)n = moles of air in the vessel headspace at the initial temperature

Mx = molecular weight of VOC species x

Pa1 = partial pressure of air at the condenser outlet temperature.

Calculation of VOC emissions using Equation 8.4-34 is based on the following assumptions:

# all of the air in the vessel headspace at the initial temperature has been expelled when

the liquid in the vessel begins to boil 

# the heated vapors leaving the still pass through a condenser

# air leaving the condenser is saturated with VOC vapors at the exit gas temperature of

the condenser.

Furthermore, while the liquid in the vessel is boiling, emissions are assumed to be zero because

only VOC vapor is expelled from the vessel and it all condenses in the condenser.

Example 8.4-10 illustrates the use of the filling and heating equations to estimate VOC emissions

from solvent reclamation.
Chapter 8 – Paint, Ink, and Other Coating Manufacturing 02/01/05

8.4-38 EIIP Volume II

Step 1: Determine Volume of Waste Solvent Charged to the Still

Q 300 tons solvent

yr 2,000 lbton gal7.21 lb

 83,218gal yr

= ⎛

⎝

⎜ ⎞

⎠

⎟ × ⎛

⎝

⎜ ⎞

⎠

⎟ × ⎛

⎝

⎜ ⎞

⎠

⎟

=

Step 2: Determine the Toluene Vapor Pressure at the Initial Temperature

Numerous resources are available for estimating vapor pressures. This example uses the Antoine

equation (Dean, 1992).

log VP A ( ) (8.4-35) B

T C x = − +

where

Example 8.4-10

The Bright Blue Paint Company in Case Study 8.3-1 recovers toluene from 300 tons/yr of waste

cleaning solvent using a batch distillation unit. What are the estimated annual VOC emissions? The

following data are given:

# The still is half filled for each distillation operation (i.e., the vessel vapor space equals the

volume of waste solvent for each batch);

# The expelled air and VOC vapors are routed to a condenser that operates with an outlet

temperature of 20°C (68°F);

# The still bottoms at the end of the distillation contain 3 percent of the initial waste solvent;

# Analysis shows the waste solvent is about 99 percent toluene (on a molar basis), and the

remaining 1 percent is dissolved solids and nonvolatile liquids;

# Typical initial temperature of the waste solvent is 25°C (77°F);

# Toluene density is 7.21 lb/gal;

# Final temperature (toluene boiling point) is 111°C (232°F); and

# Displaced air from all filling steps is assumed to be saturated with toluene vapors (i.e., the

saturation factor is 1.0).
Chapter 8 – Paint, Ink, and Other Coating Manufacturing 02/01/05

EIIP Volume II 8.4-39

VPx = vapor pressure of VOC species x, mm Hg

T = temperature, °C

A,B,C = Antoine Constants.

For toluene at the initial temperature of the still (25°C), the Antoine equation gives the following

results:

( )

log (VP ) 6.954 1,344.8

25 219.48

VP 28.4 mm Hg 0.549 psia

x

x

= − +

=

Step 3: Apply Equation 8.4-3, Determine Toluene Partial Pressure at the Initial

Temperature

( )( )

P M VP

 0.99 0.549

 0.544 psia

x x x = ×

= ×

=

Step 4: Apply Equation 8.4-1, Calculate Toluene Emissions From Charging Waste Solvent

to the Still

E 12.46 S P M Q

T

 12.46 1 0.544 9.21 83.2

537

 97 lb yr

VOC

x x = ×× × ×

= ×× × ×

=

Step 5: Apply Equations 8.4-11 and 8.4-12, Determine Amount of Noncondensable Gas in

the Vessel Headspace When Heating Begins.

Although the description of the problem doesn’t specify the size of each batch or the size of the

still, it says the headspace volume for each batch is equal to the volume of waste solvent. Thus,

the total volume of free space in the still at the start of heatup for all of the batches during the

year equals the total volume of waste solvent processed (i.e., 83,218 gal).
Chapter 8 – Paint, Ink, and Other Coating Manufacturing 02/01/05

8.4-40 EIIP Volume II

( ) ( )

( )

( )

( ) ( )

Pa 14.7 (P )

 14.7 0.544

 14.16 psia

 n 

Pa V

R (T)

 

14.16 (83,218) ft

7.48 gal

10.73 537)

 27.3lb moleof air expelled yr

1 x T1

1

3

= −

= −

=

= ×

×

=

× × ⎛

⎝

⎜ ⎞

⎠

⎟

×

=

Σ

∆

Step 6: Apply Equation 8.4-35, Determine Vapor Pressure and Partial Pressure of Toluene

at 20°C (Condenser Outlet Temperature)

( )

( )

log VP A B

T C

 6.954 1,344.8

20 219.48

VP P 21.80 mmHg 0.422 psia

x

x x

= − +

= − +

= =

Step 7: Apply Equation 8.4-34, Determine Amount of Toluene Emitted With the Expelled

Air During Heatup

( )

( )

( ) ( )( )

E 

P

Pa

 n M

 0.422

14.7 0.422 27.3 92.1

 74 lb / yr

VOC

x o

1

x = ××

= − × ×

=

∆

Step 8: Apply Equation 8.4-1, Calculate Emissions From Filling the Receiver with Distilled

Toluene at 20°C (68°F)

Note that since 3 percent of the initial waste solvent remains in the still, the total volume of

recovered toluene is 97 percent of the total waste solvent processed.
Chapter 8 – Paint, Ink, and Other Coating Manufacturing 02/01/05

EIIP Volume II 8.4-41

E 12.46 S P M Q 0.97

T

 12.46 1 0.422 92.1 83.2 0.97

528

 74 lb yr

VOC

x x = ×× × × ×

= ×× × × ×

=

Step 9: Apply Equation 8.4-1, Calculate Emissions From Filling a Storage Vessel or Drums

With Distilled Toluene From the Receiver

Assume the distilled toluene is still at 20°C (68°F)

E 12.46 S P M Q 0.97

T

 

12.46 1 0.422 92.1 83.2 0.97

528

 74 lb yr

VOC

x x = ×× × × ×

= ×× × × ×

=

Step 10: Sum the Emissions from Steps 4, 7, 8, and 9

E 97 74 74 74

319 lb yr

VOC =+++

=

4.7 Emission Model for Liquid Material Storage

The preferred method for calculating emissions from storage tanks is the use of equations

presented in AP-42. EPA has developed a software package (TANKS) for calculating these types

of emissions. The reader is referred to Chapter 1 of this volume, Introduction to Stationary Point

Source Emissions Inventory Development, for more information on using the TANKS program. 

Additionally, the reader should consult their state agency and/or the EPA’s Clearinghouse for

Inventories and Emission Factors (CHIEF) Website for the most recent version of TANKS.

4.8 Emission Model for Wastewater Treatment 

VOC emissions from a wastewater treatment system may be estimated using equations presented

in Air Emissions Models for Waste and Wastewater (EPA, 1994a), and Chapter 5, Preferred and

Alternative Methods for Estimating Air Emissions from Wastewater Collection and Treatment

Facilities, of this volume. These documents, as well as models such as WATER9 are available

on the EPA’s CHIEF Website.
Chapter 8 – Paint, Ink, and Other Coating Manufacturing 02/01/05

EIIP Volume II 8.5-1

5.0 Other Methods for Estimating Emissions

Section 4 presented models for estimating emissions from specific coating manufacturing

activities. This section presents other types of methods for calculating emissions from

manufacturing facilities. The other methods described in this section include emission factors,

material balances, and testing. 

5.1 Emission Calculations Using Emission Factors

Emission factors have long been used to calculate emissions from coating manufacturing

facilities. EPA maintains a compilation of approved emission factors in AP-42 for criteria

pollutants and hazardous air pollutants (HAPs). Available emission factors for paint

manufacturing can be found in Section 6.4 of AP-42 and in a technical memorandum from EPA

to the National Paint and Coatings Association (EPA, 1995f). Emission factors for ink

manufacturing can be found in Section 6.7 of AP-42. The National Association of Printing Ink

Manufacturers, Inc. (NAPIM), has also developed ink manufacturing emission factors (NAPIM,

1996). The most comprehensive source for toxic air pollutant emission factors is the Factor

Information and REtrieval (FIRE) data system, which also contains criteria pollutant emission

factors (EPA, 1999).

VOC emission factors are available in AP-42 for calculating total plant emissions and mixing

operation emissions from a paint manufacturing facility and for vehicle cooking and pigment

mixing emissions from an ink manufacturing facility. In addition, emission factors are available

for estimating VOC emissions from the following types of sources found in a coating

manufacturing facility:

# Solvent reclamation systems;

# Parts washing equipment; and

# Process piping (i.e., equipment leaks).

Emission factors are also available for estimating PM/PM10 emissions from coating

manufacturing facilities.

5.1.1 Total VOC Emissions from Paint Manufacturing Facilities

A VOC emission factor can be used for calculating total VOC emissions from paint

manufacturing facilities. The emission factor presented in AP-42 is essentially a loss factor that

represents an emission rate to be applied to a production rate (NPCA, 1995). The VOC emission

factor presented in AP-42 for paint manufacturing is 30 lb total VOCs/ton product (EPA, 1995b). 

To calculate total VOCs using this emission factor, see Equation 8.5-1:
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8.5-2 EIIP Volume II

(8.5-1)

where

EVOC = total emissions of VOCs from the facility (lb/yr)

EFVOC = VOC emission factor (lb VOCs/ton product)

Qp = amount of product produced (ton/yr).

Table 8.5-1. List of Variables and Symbols

Variable Symbol Units

Total VOC emissions EVOC lb/yr

VOC emission factor EFVOC various

Amount of product produced Qprod ton/yr

Emissions of VOC or PM species x Ex lb/yr

Amount of VOC species x used by the facility Qx lb/yr

Total amount of solvents used Qs lb/yr

Amount of VOC in spent solvent processed QVOC ton/yr

Concentration of VOC or PM/PM10 species x in solvent or pigment

x, respectively

Cx mass %

Mass percent of species x in total mixture Xx mass %

Volume percent of species x in total mixture Yx volume %

Number of species in total mixture n number

Flow rate through exhaust vent FR ft3

/min

Molecular weight of total mixture M lb/lb-mole

Molecular weight of VOC or PM species x Mx lb/lb-mole

Operating hours OH hr/yr

Surface area of solvent exposed to the atmosphere A ft2

Number of cleaning units in use NU cleaning units

PM/PM10 emissions EPM lb/yr

PM/PM10 emission factor EFPM lb/ton

Amount of pigment containing species x used by the facility Qx lb/yr, ton/yr

Quantity of VOC or PM species x that is received as a raw material Qr lb/yr
Table 8.5-1. (continued)

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Variable Symbol Units

EIIP Volume II 8.5-3

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Quantity of VOC or PM species x shipped out in final product Qp lb/yr

Quantity of VOC or PM species x recovered by all methods Qrec lb/yr

Quantity of VOC or PM species x contained in all waste generated Qw lb/yr

Quantity of VOC or PM species x remaining in raw material

inventory

Qxi lb/yr

Concentration of VOC or PM species x Cxt ppmv or ft3/MMft3

Because the VOC emissions calculated in Equation 8.5-1 are plantwide emissions, speciated

emissions can be estimated based on total solvent used. Speciated VOC emissions are calculated

using Equation 8.5-2:

where

Ex = Emissions of VOC species x from the facility (lb/yr);

EVOC = VOC emissions from the facility, calculated using Equation 8.5-1 (lb/yr);

Qx = Amount of VOC species x used by the facility (lb/yr); and

Qs = Total amount of solvents used by the facility (lb/yr).

With no other information available, one important assumption made in Equation 8.5-2 is that all

solvents evaporate at the same rate. The amount of VOC species x used by a facility (Qx) can be

obtained by reviewing purchase and inventory records and appropriate technical data sheets. 

Purchase and inventory records can be used to estimate the amount of a particular material

consumed. 

The sum of speciated emissions for all VOC components calculated using Equation 8.5-2 cannot

exceed the total VOC emissions calculated in Equation 8.5-1. The use of Equations 8.5-1 and

8.5-2 is demonstrated in Example 8.5-1.
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8.5-4 EIIP Volume II

Example 8.5-1

This example shows how total and speciated VOC emissions may be calculated for a paint

manufacturing facility using the production-based VOC emission factor from 

AP-42, Table 6.4-1, and Equations 8.5-1 and 8.5-2.

Given:

EFVOC = 30 lb VOC/ton product

Qprod = 1,250 ton of paint/yr

Qxylene = 250,000 lb used by the facility/yr

Qs = 1,500,000 lb solvents used by the facility/yr

Total VOC emissions would be calculated using Equation 8.5-1:

EVOC = EFVOC × Qprod

= 30 × 1,250

= 37,500 lb VOCs/yr

The amount of xylenes used by the facility (Qxylene) was estimated by conducting a review of

purchase and inventory records and technical data sheets.

Xylenes emissions would be calculated using Equation 8.5-2:

EVOC = 37,500 lb VOCs emitted/yr

Qxylene = 250,000 lb xylenes used by the facility/yr

Qs = 1,500,000 lb solvents used by the facility/yr

Exylene = EVOC × Qx/Qs

= 37,500 × 250,000/1,500,000

= 6,250 lb xylenes/yr

In addition to the 30 lb VOCs/ton product emission factor, EPA has recently restated the

emission factor for total VOC emissions for overall operations from a paint manufacturing

facility based on the amount of solvent used (EPA, 1995f). Development of the new proposed

factor, 0.034 lb VOCs emitted/lb solvent used, is based on the following information and

assumptions:

# The emission estimates used to develop the 30 lb VOCs/ton coating emission factor

appear to be based on the formulation of conventional coatings that were prevalent in

the late 1950s and early 1960s.

# Densities for conventional coatings were typically 10 to 15 lb/gal (an average density

of 12.5 lb/gal was used) during the late 1950s and early 1960s.
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(8.5-4)

# An average solvent content of 5.5 lb VOCs/gal coating was assumed for conventional

coatings (EPA, 1995f).

Use of the proposed factor by facilities that primarily manufacture water-based, low-solvent, or

high-solids coatings should result in more accurate emissions than use of the 30 lb VOCs/ton

coating factor.

To calculate total VOCs using this proposed emission factor, use Equation 8.5-3:

where

EVOC = total VOC emissions from a facility (lb/yr)

EFVOC = VOC emission factor (lb VOCs/lb solvent used)

Qs = total amount of solvents used (lb/yr). 

Speciated emissions are then calculated using Equation 8.5-4:

where

Ex = emissions of VOC species x from a facility (lb/yr)

EFVOC = VOC emission factor (lb VOCs/lb solvent used)

Qx = amount of VOC species x used by the facility (lb/yr).

The sum of speciated emissions for all VOC components calculated in Equation 8.5-4 cannot

exceed the total VOC emissions calculated in Equation 8.5-3. The use of Equations 8.5-3 

and 8.5-4 is demonstrated in Example 8.5-2.

5.1.2 VOC Emissions from Paint Mixing Operations

VOC emissions from paint mixing equipment may be calculated using emission factors. AP-42

suggests that “about 1 or 2 percent of solvent is lost even under very well controlled conditions”

(EPA, 1995b). This percentage range can be translated into an emission factor range of 0.01 to

0.02 lb solvent lost/lb solvent used. Review of background information indicates that this

emission factor range applies specifically to paint mixing operations (i.e., operations where

solvents are added as raw materials) (EPA, 1995f).

AP-42 states that the consumption-based emission factor of 0.01 to 0.02 lb VOCs lost/lb solvent

used applies even to facilities that have emission sources that are well controlled. If a facility
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8.5-6 EIIP Volume II

Example 8.5-2

This example shows how total and speciated VOC emissions may be calculated for a paint

manufacturing facility using the proposed solvent-based VOC emission factor, as shown in

Equation 8.5-3.

EFVOC = 0.034 lb VOCs/lb solvent used

Qs = 350,000 lb solvents used by the facility/yr

EVOC = EFVOC × Qs

= 0.034 × 350,000

= 11,900 lb VOCs/yr

Xylene emissions would be calculated using Equation 8.5-4:

EFVOC = 0.034 lb VOCs/lb solvent

Qx = 15,000 lb xylenes contained in solvents used by the facility/yr

Ex = EFVOC × Qx

= 0.034 × 15,000

= 510 lb xylenes/yr

(8.5-5)

contains mixers or other process vessels that are uncovered or otherwise poorly controlled, an

emission factor greater than 0.02 lb solvent lost/lb solvent used may need to be applied (NPCA,

1995).

Total VOC emissions can also be calculated by summing the speciated VOC emissions. 

Use Equation 8.5-5 for calculating speciated VOC emissions from mixers using the

consumption-based emission factor.

where

Ex = emissions of VOC species x from mixing equipment (lb/yr)

EFVOC = VOC emission factor (lb VOCs/lb solvent used)

Qx = amount of VOC species x added to mixing equipment as a raw material

(lb/yr).
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EIIP Volume II 8.5-7

Example 8.5-3

This example shows how speciated VOC emissions from mixing equipment may 

be calculated using Equation 8.5-5 and the emission factor from Section 6.4.1 of

AP-42. This example assumes an average level of VOC control on process 

equipment. Consequently, the average of the range (1 to 2 percent) reported in 

AP-42 is used.

EFVOC = 0.015 lb xylenes emitted/lb xylenes used

Qx = 15,000 lb xylenes added to mixing equipment/yr

Ex = EFVOC × Qx

= 0.015 × 15,000 

= 225 lb xylenes/yr

(8.5-6)

The amount of VOC species x used in mixing equipment (Qx) refers to the total amount of VOC

species x that is added to mixing equipment as a raw material. Once the solvent is mixed with

other materials, it is no longer considered a raw material. 

The use of Equation 8.5-5 is also demonstrated in Example 8.5-3.

5.1.3 VOC Emissions from Ink Manufacturing Facilities

Emission factors are also available for VOC sources from ink manufacturing facilities. Section

6.7 of AP-42 presents VOC emission factors for vehicle cooking. NAPIM has also developed

VOC emission factors for mixing, milling, and tub wash processes for both paste and liquid inks

(NAPIM, 1996). Emission factors are available for sheetfed three-roll mill and heatset paste

inks, and for low-VOC and high-VOC liquid inks. Equation 8.5-6 can be used to estimate

emissions using emission factors.

where

EVOC = VOC emissions (lb/yr)

EFVOC = VOC emission factor (lb VOC/ton product)

Qp = amount of product produced (ton/yr).

Speciated emissions can be calculated using Equation 8.5-7:
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8.5-8 EIIP Volume II

Example 8.5-4

This example shows how VOC and speciated VOC emissions may be calculated for general vehicle

cooking at an ink manufacturing facility using the production-based VOC emission factor from AP42, Table 6.7-1, and Equations 8.5-6 and 8.5-7.

Given:

EFVOC = 120 lb VOC/ton product

Qp = 500 tons of ink/yr

Qtoluene = 100,000 lb used/yr

Qs = 1,000,000 lb solvents used/yr

VOC emissions would be calculated using Equation 8.5-6:

EVOC = EFVOC × Qp

= 120 × 500

= 60,000 lb VOCs/yr

The amount of toluene used (Qtoluene) was estimated by conducting a review of purchase and

inventory records, batch records, and technical data sheets.

Toluene emissions would be calculated using Equation 8.5-7:

EVOC = 60,000 lb VOCs emitted/yr

Qtoluene = 100,000 lb toluene used/yr

Qs = 1,000,000 lb solvents used/yr

Etoluene = EVOC × Qx/Qs

= 60,000 × 100,000/1,000,000

= 6,000 lb toluene/yr

E E QQ (8.5-7) x VOC x s = ×

where

Ex = emissions of VOC species x (lb/yr)

EVOC = VOC emissions calculated using Equation 8.5-6 (lb/yr)

Qx = amount of VOC species x used (lb/yr)

Qs = total amount of solvent used (lb/yr).

With no other information available, one important assumption made in Equation 8.5-7 is that all

solvents evaporate at the same rate. The amount of VOC species x used by a facility (Qx) can be

obtained by reviewing purchase and inventory records and appropriate technical data sheets. 

Purchase and inventory records can be used to estimate the amount of a particular material

consumed. 

Example 8.5-4 illustrates the use of these equations.
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(8.5-9)

(8.5-10)

5.1.4 Total and Speciated VOC Emissions from Solvent Reclamation

VOC emissions from the loading and operation of a distillation device may be calculated using

emission factors (EPA, 1995d). 

To calculate total VOCs from loading or operation of the distillation device, use 

Equation 8.5-8:

where

EVOC = VOC emissions from loading or operation of the distillation device (lb/yr)

EFVOC = VOC emission factor for loading of the distillation device or for the

distillation column condenser vent (lb VOCs emitted/ton VOCs processed)

QVOC = amount of VOC in spent solvent processed through the distillation device

(ton/yr). 

Speciated VOC emissions are then calculated using Equation 8.5-9:

where

Ex = emissions of VOC species x from loading or operation of the distillation

device (lb/yr)

EVOC = VOC emissions from loading or operation of the distillation device,

calculated using Equation 8.5-9 (lb/yr)

Cx = concentration of VOC species x in the solvent processed through the

distillation system (mass %).

Example 8.4-5 illustrates the use of Equations 8.5-8 and 8.5-9.

If the species x concentration is provided on a volume basis, the volume percent will need to be

converted to mass percent. If molecular weight of the total mixture is known, the volume percent

of species x in the total mixture can be converted to mass percent using Equation 8.5-10:
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8.5-10 EIIP Volume II

(8.5-11)

Example 8.5-5

First, total VOC emissions from operation of a distillation device may be calculated using an

emission factor from AP-42, Table 4.7-1 and Equation 8.5-8.

EFVOC = 3.30 lb VOCs/ton solvent processed

QVOC = 5 tons spent solvent processed/yr

EVOC = EFVOC × QVOC 

= 3.30 × 5

= 16.5 lb VOCs emitted/yr

Next, total VOC emissions are speciated using the concentration of VOC species x (mass %) and

Equation 8.5-9.

EVOC = 16.5 lb VOCs/yr (calculated above);

Cx = 99% toluene in spent solvent

Ex = EVOC × Cx/100

= 16.5 × 99/100

= 16.3 lb toluene emitted/yr

where

Xx = mass percent of species x in total mixture

Yx = volume percent of species x in total mixture

Mx = molecular weight of species x

M = molecular weight of total mixture.

If molecular weight of the total mixture is not known, the volume percent can be converted to

mass percent using Equation 8.5-11:

where

M = molecular weight of total mixture

n = number of species in total mixture

Yx = volume percent of species x in total mixture

Mx = molecular weight of species x.
Chapter 8 – Paint, Ink, and Other Coating Manufacturing 02/01/05

3 Certain halogenated solvents that are widely used for solvent cleaning (e.g., 1,1,1-trichloroethane) have

been categorized as “VOC-exempt” by various state and federal regulations. However, the emission factors reported

in AP-42 are still applicable for these solvents (EPA, 1995e).

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(8.5-12)

(8.5-13)

(8.5-14)

5.1.5 VOC Emissions from Parts Cleaning

VOC emission factors for parts cleaning in cold cleaners, open-top vapor degreasers, or

conveyorized degreasers are presented in AP-42. Emission factors for cold cleaners and vapor

degreasers are in units of tons VOC/yr/unit or lb VOC/hr/ft2

. Emission factors for vapor and

nonboiling conveyorized degreasers are presented only in units of ton VOC/yr/unit. If using

emission factors based on the surface area of the exposed solvent, use Equation 8.5-12.

where

EVOC = VOC emissions from a cold cleaner or open-top vapor degreaser (lb/yr)

EFVOC

3 = VOC emission factor for cold cleaners or open-top vapor degreasers

(lb/hr/ft2

)

A = surface area of solvent exposed to the atmosphere (ft2)

OH = hours per year that the cold cleaner or vapor degreaser is in operation

(hr/yr). 

If using emission factors based on the number of cleaning units, use Equation 8.5-13.

where

EVOC = VOC emissions from a cold cleaner, an open-top vapor degreaser, or a

conveyorized degreaser (lb/yr)

EFVOC = VOC emission factor for cold cleaners, open-top vapor degreasers, or

conveyorized degreasers (ton/yr/unit)

NU = number of cleaning units in use (units)

2000 = 2,000 lb/ton.

Speciated VOC emissions from parts cleaning may be calculated using Equation 8.5-14:
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8.5-12 EIIP Volume II

Example 8.5-6

This example shows how total and speciated VOC emissions from a cold cleaner may be

calculated using Equations 8.5-12 and 8.5-14 and an emission factor (from AP-42, Table 4.6-2)

that is based on the surface area of the exposed solvent. First, total VOC emissions are calculated

using 

Equation 8.5-12.

EFVOC = 0.08 lb/hr/ft2

A = 5.25 ft2

OH = 3,000 hr/yr

EVOC = EFVOC × A × OH

= 0.08 × 5.25 × 3,000

= 1,260 lb VOC/yr

Next, total VOC emissions are speciated using the concentration of VOC 

species x (mass %) and Equation 8.5-14.

EVOC = 1,260 lb VOCs/yr (calculated above)

Cx = 99% trichloroethylene in cleaning solvent

Ex = EFVOC × Cx/100

= 1,260 × 99/100

= 1,247 lb trichloroethylene/yr

where

Ex = emissions of VOC species x from parts cleaning (lb/yr)

EVOC = VOC emissions calculated using Equation 8.5-11 or 8.5-12 (lb/yr)

Cx = concentration of VOC species x in cleaning solvent (mass %).

Examples 8.5-6 and 8.5-7 show the application of Equations 8.5-12, 8.5-13, and 8.5-14.
Chapter 8 – Paint, Ink, and Other Coating Manufacturing 02/01/05

EIIP Volume II 8.5-13

Example 8.5-7

This example shows how total VOC emissions are calculated from several cold cleaners using

Equation 8.5-13 and an emission factor from Table 4-6.2 of AP-42.

EFVOC = 0.33 ton/yr/unit

NU = 5 units

EVOC = EFVOC × NU × 2,000

= 0.33 × 5 × 2,000

= 3,300 lb VOC/yr

5.1.6 VOC Emissions from Equipment Leaks 

Emissions factors for equipment leaks from pumps, valves, and connectors in the coating

manufacturing industry were developed from a bagging study conducted to develop equations

correlating total organic carbon readings as methane (obtained using Method 21) to VOC

emission rate. Using these equations and method 21 screening data for facilities in the industry,

average uncontrolled VOC emission factors, on a per component basis, were developed and are

presented in the following table (Shine, 2003):

Table 8.5-2. Emission Factors for Equipment Components at

Coatings Manufacturing Facilities

Component

Average Emission Factor

kg/hr/component lb/hr/component

Pumps 0.004219 0.009301

Valves 0.000412 0.000908

Connectors 0.000015 0.000033

Additional information regarding various techniques for estimating equipment leak emissions is

provided in Chapter 4 of this volume. Example 8.5-8 shows application of the emission factors

in Table 8.5-2 to the equipment components for the Bright Blue Paint Company described in

Case Study 8.3-1 of this chapter.
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(8.5-16)

5.1.7 PM/PM10 Emissions from a Paint or Ink Manufacturing Facility

AP-42 also presents PM emission factors from paint and ink manufacturing, which are based on

the amount of pigment used by a facility. The AP-42 factor for paint manufacturing is 20 lb

PM/ton pigment. The AP-42 factor for pigment mixing at an ink manufacturing facility is 2 lb

PM/ton pigment. To calculate PM emissions using these emission factors, use Equation 8.5-15.

where

EPM = total PM emissions (lb/yr)

EFPM = PM emission factor (lb PM/ton pigment)

GQx = total pigment (ton/yr).

PM10 can conservatively be estimated by assuming that all of the PM emitted is PM10.

Speciated PM emissions are calculated using Equation 8.5-16:

where

Ex = total emissions of PM species x (lb/yr)

EFPM = PM emission factor from AP-42, Table 6.4-1 or Table 6.7-1 (lb PM/ton

pigment)

Qx = amount of pigment containing species x used by the facility (ton/yr)

Cx = Concentration of PM species x in pigment x (mass %).

Example 8.5-8

The Bright Blue Paint Company in Case Study 8.3-1 uses 15 valves, 10 pumps, and 50 connectors in

paint manufacturing operations. Assuming these equipment components are in service 8,760 hr/yr,

what are the estimated annual VOC emissions from equipment leaks?

EVOC = (15 values × 0.000908 lb/hr/valve +

10 pumps × 0.009301 lb/hr/pump +

50 connectors × 0.000033 lb/hr/connector) × 8,760 hr/yr

= 949 lb/yr
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EIIP Volume II 8.5-15

Example 8.5-9

This example demonstrates how speciated PM emissions from pigment mixing at an ink

manufacturing facility may be calculated using the consumption-based PM emission factor from

Table 6.7-1 of AP-42 and Equation 8.5-16:

EFPM = 2 lb PM/ton pigment

Qx = 5 tons ZnO/yr

Cx = 80% Zn in ZnO

Ex = EFPM × Qx × Cx/100

= 2 × 5 × 80/100

= 8 lb Zn/yr

Use of Equation 8.5-16 is demonstrated in Example 8.5-9.

5.2 VOC and PM Emission Calculations Using Material Balance

The material balance method requires the totaling of all materials received at the plant and then

subtracting out all of the known losses or transfers of the material off-site (including finished

product and waste material). The difference is assumed to have been emitted to the atmosphere. 

The quantity received and the quantity lost or used should be for the same time period, typically

January 1 to December 31 for the year of the inventory (NPCA, 1995).

Use Equation 8.5-17 for calculating emissions using the material balance approach.

Ex = Qr

 - Qp - Qrec - Qw - Qxi (8.5-17)

where

Ex = emissions of VOC or PM species x (lb/yr)

Qr = quantity of VOC or PM species x that is received as a raw material (lb/yr)

Qp = quantity of VOC or PM species x that is shipped out in the final product

(lb/yr)

Qrec = quantity of VOC or PM species x that is recovered by all methods (e.g.,

solvent recovery) (lb/yr)

Qw = quantity of VOC or PM species x that is contained in all waste generated

during the evaluation period (e.g., wastewater, sludge, drum residue)

(lb/yr)

Qxi = quantity of VOC or PM species x that remains in the raw material

inventory (lb/yr).
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8.5-16 EIIP Volume II

Example 8.5-10

This example shows how total ethylene glycol emissions for a paint manufacturing facility may be

calculated using Equation 8.5-17. Data are as follows:

# In a given year, a paint facility receives 100,000 lb of ethylene glycol (Qr).

# Based on the total amount of product shipped off-site and records of product composition,

the facility estimates that the amount of ethylene glycol shipped out in final product (Qp) is

69,000 lb;

# Based on waste composition analyses, the amount of waste sent off-site, and wastewater

discharge rates, the facility estimates that the amount of ethylene glycol that was found in

all wastes generated during the year (Qw) is 5,000 lb; and

# The amount of ethylene glycol that was found to be in the facility’s inventory at the end of

the evaluation period (Qxi) is 15,000 lb.

Emission of ethylene glycol are calculated as follows:

Ex = Qr

 - Qp - Qrec - Qxi

= 100,000 - 69,000 - 10,000 - 5,000 - 15,000

= 1,000 lb ethylene glycol/yr

(8.5-18)

The use of Equation 8.5-17 is demonstrated in Example 8.5-10.

5.3 Emission Calculations Using Test Data

Because vent or stack testing is relatively uncommon for paint and ink manufacturing facilities,

emissions test data for these plants are typically in the form of exposure monitoring results. 

Industrial hygiene data may be used in conjunction with exhaust system flow rates to calculate

fugitive emissions from a room, floor, or building (NPCA, 1995). Use Equation 8.5-18 for

calculating these emissions.

where

Ex = emissions of VOC or PM species x (lb/yr)

FR = flow rate through exhaust ventilation system (ft3/min)
Chapter 8 – Paint, Ink, and Other Coating Manufacturing 02/01/05

EIIP Volume II 8.5-17

Example 8.5-11

This example shows how Equation 8.5-18 is used to calculate fugitive emissions of xylenes from a

building where several mixing vessels are located. The following data are given:

# The building exhaust flow rate (FR) is 20,000 ft3/min;

# The exhaust system operates for 7,920 hr/yr (OH);

# Industrial hygiene data indicate that the concentration of mixed xylenes in the building

(Cxt) is 0.1 ppmv; and

# The molecular weight of mixed xylenes (Mx) is 106 lb/lb-mole.

Xylenes emissions are calculated as follows:

Ex = FR × 60 × OH × Cxt × 0.0026 × Mx

1 × 106

= 20,000 × 60 × 7,920 × 0.1 × 0.0026 × 106

1 × 106

= 262 lb xylenes/yr

60 = 60 min/hr

OH = hours per year that the exhaust system is operational (hr/yr)

Cxt = concentration of VOC or PM species x (ppmv or ft3

/MMft3)

0.0026 = molar volume of gas at 68°F (mole/ft3

)

Mx = molecular weight of VOC or PM species x (lb/lb-mole)

1 × 106 = 1 × 106

 ft3/MMft3.

Example 8.5-11 illustrates the use of Equation 8.5-18.

VOC losses from certain operations (e.g., filling of containers) may also be measured by

performing a study using a gravimetric analysis such as American Society For Testing and

Materials (ASTM) Standard D2369, Test Method for Volatile Content of Coatings. The

operation under evaluation could be simulated on a small scale, and VOC analysis would be

conducted on samples taken before and after the simulated activity (EPA, 1992b).
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8.5-18 EIIP Volume II

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EIIP Volume II 8.6-1

6.0 References

Bureau of the Census. 1997. The Current Industrial Report for Paint, Varnish, and Lacquer

(MA28F) - 1996. United States Department of Commerce. Pages 2 and3.

Crowl, Daniel and Louvar, Joseph. 2002. Chemical Process Safety, Fundamentals With

Applications. Second Edition. Practice Hall PTR, Upper Saddle River, NJ 07458. 

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Dean, John, Editor. 1992. Lange’s Handbook of Chemistry. Fourteenth Edition. McGraw-Hill.

EIIP. 1996. Preferred and Alternative Methods for Estimating Air Emissions from Hot-Mix

Asphalt Plants, Final Report. Prepared for the Point Sources Committee, Emission Inventory

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Environmental Protection Agency, Office of Air Quality Planning and Standards. Research

Triangle Park, North Carolina.

EIIP. 2000. How to Incorporate The Effects of Air Pollution Control Device Efficiencies and

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Quality Planning and Standards. Research Triangle Park, North Carolina. (EIIP Internet address

http://www.epa.gov/ttn/chief/eiip).

EPA. 1987. Estimating Releases and Waste Treatment Efficiencies for the Toxic Chemical

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Substances, EPA-560/4-88-002. Washington, D.C.

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EPA. 1992a. Control of VOC Emissions from Ink and Paint Manufacturing Processes. U.S.

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Triangle Park, North Carolina.
Chapter 8 – Paint, Ink, and Other Coating Manufacturing 02/01/05

8.6-2 EIIP Volume II

EPA. 1994a. Air Emissions Models for Waste and Wastewater. U.S. Environmental Protection

Agency, Office of Air Quality Planning and Standards, EPA-453/R-94-080a. Research Triangle

Park, North Carolina.

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Alternate Control Techniques. U.S. Environmental Protection Agency, Office of Air Quality

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Area Sources, Fifth Edition, AP-42. Section 7.1, Organic Liquid Storage Tanks. U.S.

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Triangle Park, North Carolina.

EPA. 1995b. Compilation of Air Pollutant Emission Factors. Volume I: Stationary Point and

Area Sources, Fifth Edition, AP-42. Section 6.4, Paint and Varnish. U.S. Environmental

Protection Agency, Office of Air Quality Planning and Standards. Research Triangle Park, North

Carolina.

EPA. 1995c. Compilation of Air Pollutant Emission Factors. Volume I: Stationary Point and

Area Sources, Fifth Edition, AP-42. Section 5.2, Transportation and Marketing of Petroleum

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Area Sources, Fifth Edition, AP-42. Section 4.7, Waste Solvent Reclamation. U.S.

Environmental Protection Agency, Office of Air Quality Planning and Standards. Research

Triangle Park, North Carolina.

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Area Sources, Fifth Edition, AP-42. Section 4.6, Solvent Degreasing. U.S. Environmental

Protection Agency, Office of Air Quality Planning and Standards. Research Triangle Park, North

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EPA. 1995f. Memorandum on AP-42 Emission Factors for the Paint and Varnish Industry from

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Coatings Association. Washington, D.C.
Chapter 8 – Paint, Ink, and Other Coating Manufacturing 02/01/05

EIIP Volume II 8.6-3

EPA. 1995g. Protocol for Equipment Leak Emission Estimates. U.S. Environmental Protection

Agency, Office of Air Quality Planning and Standards, EPA-453/R-95-017. Research Triangle

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Area Sources, Fifth Edition, AP-42. Section 7.1, Organic Liquid Storage Tanks. U.S.

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Triangle Park, North Carolina.

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Fisher, Perry W., Steven A. Frey, and Kaushik Deb. 1993. Emission Estimation Methodologies

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presented at the 86th Annual Meeting and Exhibition, Denver, Colorado, June 13-18, 1993.

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Chapter 8 – Paint, Ink, and Other Coating Manufacturing 02/01/05

8.6-4 EIIP Volume II

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Park Ridge, New Jersey.

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