PAINTING BASICS AND EMISSION CALCULATIONS 

FOR TCEQ AIR QUALITY PERMIT APPLICATIONS 

NOVEMBER 5, 2012

TEXAS COMMISSION ON 

ENVIRONMENTAL QUALITY

Protecting Texas by Reducing

And

Preventing Pollution

Presented by:

Mike Coldiron, P.E. 

Texas Commission on Environmental Quality

Austin, Texas
1

INTRODUCTION 

Surface coated products are all around, and coatings are applied to many types of industrial 

equipment and consumer products to provide decorative and protective finishes as well as 

functional uses such as adhesives. The application of these finishes, while improving product 

performance or extending product life, releases significant emissions of solvents and solids into 

the environment. As such, the EPA, state, and local authorities have promulgated regulations 

that limit coating solvent content, emission rates, solvent, and solid species limits to reduce the 

formation of ground level ozone and to protect public health from unhealthy levels of exposure 

to solids and solvents. In addition to the state and federal industry-wide rules, all facilities in 

Texas that emit air contaminants into the air of the State of Texas must obtain a preconstruction 

permit authorization before construction of the facility is begun, as required by Title 30 Texas 

Administrative Code (30 TAC) §116.110.

There are a number of methods to demonstrate compliance with the emission limits in 

regulations or to estimate emissions for preconstruction authorizations such as AP-42 emission 

factors, stack sampling, coating solvent testing, or the use of continuous emission monitors. 

Emission factors lack accuracy and even applicability to a specific type of process or product 

type. Stack sampling and continuous monitors are expensive and lack the ability to demonstrate 

compliance with coating solvent content limits. Monitors also tell the facility about a problem or 

potential violation only after it has occurred. Coating solvent content testing may be used both 

before and after the application of the coating, but this can be expensive and inconvenient. 

Emission calculations effectively deal with many of these problems and reduce compliance 

demonstration costs, prevent violations, allow the facility to set appropriate emission limits 

during permitting, and provide important cost and process information to facility management. 

However, the accuracy of the calculations is dependent on the quality of the data used in the 

calculations, and the level of effort required to produce the results is dependent on the how well

the data is organized. The purpose of this paper is to provide environmental professionals with 
2

the necessary background to collect usable data, organize the data, and use the data to 

successfully complete emission calculations for a number of types of emission standards and 

limits. 

REASONS TO CALCULATE EMISSIONS FROM SURFACE COATING SOURCES

Traditionally, calculations were carried out after the fact in response to regulatory requirements 

and were looked upon as a burden to the facility. However, emission calculations provide both 

predictive and retrospective evaluations of surface coating facility operations from an 

environmental and business perspective. Rather than being viewed by management as an 

expense, emission calculations can provide opportunities for process improvement and 

reductions in operating costs.

The retrospective use of emission calculations is primarily for demonstration of compliance with 

regulatory requirements such as the following:

 Federal New Source Performance Standards (NSPS) under Title 40 Code of Federal 

Regulations, Part 60 (40 CFR 60);

 Federal National Emission Standards for Hazardous Air Pollutants (NESHAPs) under 

40 CFR 63;

 State Reasonably Available Control Technology (RACT) requirements;

 State and federal construction permits; and 

 State and federal operating permits under 40 CFR 70; 

Retrospective uses also include the determination of emissions for historical purposes such as the 

following:

 Emission Inventories;

 Calculation of Emission Fees; and 
3

 The quantity of emissions released during emissions events (formerly known as 

‘upsets’). 

Prospective uses allow the facility to ensure compliance before the fact in areas such as the 

following:

 Air quality construction permit applications;

 Determination of applicability of State and federal permit programs;

 Evaluation of new processes and products to determine if they will be compliant with 

State and federal rules before introduction; 

 Monitor process performance and reduce production costs through improvements in 

transfer efficiency and increasing coatings solids content;

 Determination of optimal operating points for volatile organic compound (VOC) and 

particulate matter (PM) emission controls;

 Production scheduling to maintain compliance with RACT, NSPS, and NESHAP 

rules that allow for averaging to comply with the standard; 

Well-organized and complete emission calculations in both modes will result in greater 

confidence in facility management of the ability of the facility to meet applicable requirements. 

DEFINITIONS 

Emission calculations are more easily understood if the exact wording of regulatory definitions 

and their limitations are understood. What the definitions do not say is as important as what they 

do say as well as how they are related to each other. 

Coating – A material applied onto or impregnated into a substrate for protective, 

decorative or functional purposes. Such materials include, but are not limited to, paints, 

varnishes sealants, adhesives, thinners, diluents, inks, maskants, and temporary protective 

coatings.
4

Coating application system – Devices or equipment designed for the purpose of 

applying a coating material to a surface. The devices may include, but are not limited to, 

brushes, sprayers, flow coaters, dip tanks, rollers, knife coaters, and extrusion coaters.

Coating line – An operation consisting of a series of one or more coating application 

systems and including associated flashoff area(s), drying area(s), and oven(s) wherein a 

surface coating is applied, dried, or cured.

Coating solids (or solids) – The part of the coating that remains after the coating is dried 

or cured.

Capture efficiency – The amount of VOC collected by a capture system that is expressed 

as a percentage derived from the weight per unit time of VOC entering a capture system 

and delivered to a control device divided by the weight per unit time of total VOC 

generated by a source of VOC.

Exempt solvent – Those carbon compounds or mixtures of carbon compounds that have 

been excluded from the definition of volatile organic compound.

Hazardous air pollutant – Means any air pollutant listed in or pursuant to section 112(b) 

of the [Federal Clean Air] Act. Hazardous air pollutants (HAPs) are as follows:

CAS No. Pollutant CAS No. Pollutant

75070 Acetaldehyde 79118 Chloroacetic acid

60355 Acetamide 532274 2-Chloroacetophenone

75058 Acetonitrile 108907 Chlorobenzene

98862 Acetophenone 510156 Chlorobenzilate

53963 2-Acetylaminofluorene 67663 Chloroform

107028 Acrolein 107302 Chloromethyl methyl ether

79061 Acrylamide 126998 Chloroprene

79107 Acrylic acid 1319773 Cresols/Cresylic acid (isomers and mixture)

107131 Acrylonitrile 95487 o-Cresol

107051 Allyl chloride 108394 m-Cresol
5

CAS No. Pollutant CAS No. Pollutant

92671 4-Aminobiphenyl 106445 p-Cresol

62533 Aniline 98828 Cumene 

90040 o-Anisidine 94757 2,4-D (2,4-Dichlorophenoxyacetic Acid) 

(including salts and esters)

1332214 Asbestos 3547044 DDE (1,1-dichloro-2,2-bis(p-chlorophenyl) 

ethylene)

71432 Benzene (including benzene from gasoline) 334883 Diazomethane

92875 Benzidine 132649 Dibenzofuran 

98077 Benzotrichloride 96128 1,2-Dibromo-3-chloropropane 

100447 Benzyl chloride 84742 Dibutylphthalate

92524 Biphenyl 106467 1,4-Dichlorobenzene (p)

117817 Bis (2-ethylhexyl) phthalate (DEHP) 91941 3,3-Dichlorobenzidene 

542881 Bis (chloromethyl) ether 111444 Dichloroethyl ether (Bis[2-chloroethyl]ether)

75252 Bromoform 542756 1,3-Dichloropropene

106990 1,3-Butadiene 62737 Dichlorvos

156627 Calcium cyanamide 111422 Diethanolamine

133062 Captan 121697 N,N-Diethyl aniline (N,N-Dimethylaniline)

63252 Carbaryl 64675 Diethyl sulfate

75150 Carbon disulfide 119904 3,3-Dimethoxybenzidine

56235 Carbon tetrachloride 60117 Dimethyl aminoazobenzene

463581 Carbonyl sulfide 119937 3,3'-Dimethyl benzidine

120809 Catechol 79447 Dimethyl carbamoyl chloride

133904 Chloramben 68122 Dimethyl formamide 

57749 Chlordane 57147 1,1-Dimethyl hydrazine

7782505 Chlorine 131113 Dimethyl phthalate

77781 Dimethyl sulfate 72435 Methoxychlor 

534521 4,6-Dinitro-o-ocresol (including salts) 74839 Methyl bromide (Bromomethane)

51285 2,4-Dinitrophenol 74873 Methyl chloride (Chloromethane) 

121142 2,4-Dinitrotoluene 71556 Methyl chloroform (1,1,1-Trichloroethane) 

123911 1,4-Dioxane (1,4-Diethyleneoxide) 60344 Methyl hydrazine

122667 1,2-Diphenylhydrazine 74884 Methyl iodide (Iodomethane)

106898 Epichlorohydrin (1-Chloro-2,3-

epoxypropane)

108101 Methyl isobutyl ketone (Hexone)

106887 1,2-Epoxybutane 624839 Methyl isocyanate 

140885 Ethyl acrylate 80626 Methyl methacrylate 

100414 Ethyl benzene 1634044 Methyl tert butyl ether

51796 Ethyl carbamate (Urethane) 101144 4,4-Methylene bis (2-chloroaniline) 

75003 Ethyl chloride (Chloroethane) 75092 Methylene chloride (Dichloromethane)

106934 Ethylene dibromide (Dibromoethane) 101688 Methylene diphenyl diisocyanate (MDI)
6

CAS No. Pollutant CAS No. Pollutant

107062 Ethylene dichloride (1,2-Dichloroethane) 101779 4,4'-Methylenedianiline 

107211 Ethylene glycol 91203 Naphthalene 

151564 Ethylene imine (Aziridine) 98953 Nitrobenzene

75218 Ethylene oxide 92933 4-Nitrobiphenyl

96457 Ethylene thiourea 100027 4-Nitrophenol 

75343 Ethylidene dichloride (1,1-Dichloroethane) 79469 2-Nitropropane

50000 Formaldehyde 684935 N-Nitroso-N-methylurea

76448 Heptachlor 62759 N-Nitrosodimethylamine

118741 Hexachlorobenzene 59892 N-Nitrosomorpholine

87683 Hexachlorobutadiene 56382 Parathion

77474 Hexachlorocyclopentadiene 82688 Pentachloronitrobenzene (Quintobenzene)

67721 Hexachloroethane 87865 Pentachlorophenol 

822060 Hexamethylene-1,6-diisocyanate 108952 Phenol

680319 Hexamethylphosphoramide 106503 p-Phenylenediamine

110543 Hexane 75445 Phosgene

302012 Hydrazine 7803512 Phosphine 

7647010 Hydrochloric acid 7723140 Phosphorus

7664393 Hydrogen fluoride (Hydrofluoric acid) 85449 Phthalic anhydride

7783064 Hydrogen sulfide 1336363 Polychlorinated biphenyls (Aroclors)

123319 Hydroquinone 1120714 1,3-Propane sultone 

78591 Isophorone 57578 beta-Propiolactone

58899 Lindane (all isomers) 123386 Propionaldehyde 

108316 Maleic anhydride 114261 Propoxur (Baygon) 

67561 Methanol 78875 Propylene dichloride (1,2-Dichloropropane)

75569 Propylene oxide 593602 Vinyl bromide 

75558 1,2-Propylenimine (2-Methyl aziridine) 75014 Vinyl chloride

91225 Quinoline 75354 Vinylidene chloride (1,1-Dichloroethylene)

106514 Quinone 1330207 Xylenes (isomers and mixture)

100425 Styrene 95476 o-Xylenes

96093 Styrene oxide 108383 m-Xylenes 

1746016 2,3,7,8-Tetrachlorodibenzo-p-dioxin 106423 p-Xylenes

79345 1,1,2,2-Tetrachloroethane Antimony Compounds Antimony Compounds 

127184 Tetrachloroethylene (Perchloroethylene) Arsenic Compounds Arsenic Compounds (inorganic including arsine)

7550450 Titanium tetrachloride Beryllium Compounds Beryllium Compounds 

108883 Toluene Cadmium Compounds Cadmium Compounds

95807 2,4-Toluene diamine Chromium Compounds Chromium Compounds

584849 2,4-Toluene diisocyanate Cobalt Compounds Cobalt Compounds

95534 o-Toluidine Coke Oven Emissions Coke Oven Emissions 
7

CAS No. Pollutant CAS No. Pollutant

8001352 Toxaphene (chlorinated camphene) Cyanide Compounds 1 Cyanide Compounds 1

120821 1,2,4-Trichlorobenzene Glycol ethers2 Glycol ethers2

79005 1,1,2-Trichloroethane Lead Compounds Lead Compounds

79016 Trichloroethylene Manganese Compounds Manganese Compounds

95954 2,4,5-Trichlorophenol Mercury Compounds Mercury Compounds

88062 2,4,6-Trichlorophenol Fine mineral fibers3Fine mineral fibers 3

121448 Triethylamine Nickel Compounds Nickel Compounds

1582098 Trifluralin Polycyclic Organic 

Matter4

Polycyclic Organic Matter 4

540841 2,2,4-Trimethylpentane Radionuclides 

(including radon)5

Radionuclides (including radon) 5

108054 Vinyl acetate Selenium Compounds Selenium Compounds 

For all listings above which contain the word "compounds" and for glycol ethers, the following 

applies: Unless otherwise specified, these listings are defined as including any unique chemical 

substance that contains the named chemical (i.e., antimony, arsenic, etc.) as part of that 

chemical's infrastructure.

1 X'CN where X = H' or any other group where a formal dissociation may occur. For example 

KCN or Ca(CN)2

2: Glycol ethers include mono- and di-ethers of ethylene glycol, diethylene glycol, and 

triethylene glycol R-(OCH2CH2)n-OR′.

Where:

n = 1, 2, or 3;

R = alkyl C7 or less; or

R = phenyl or alkyl substituted phenyl;

R′= H or alkyl C7 or less; or

OR′ consisting of carboxylic acid ester, sulfate, phosphate, nitrate, or sulfonate.

3 Includes mineral fiber emissions from facilities manufacturing or processing glass, rock, or 

slag fibers (or other mineral derived fibers) of average diameter 1 micrometer or less.

4 Includes organic compounds with more than one benzene ring, and which have a boiling point 

greater than or equal to 100 o C. 

5 A type of atom which spontaneously undergoes radioactive decay. 

 The substance caprolactam (CAS number 105602) is deleted from the list of hazardous air 

pollutants established by 42 U.S.C. 7412(b)(1). [61 FR 30823, June 18, 1996]

 The substance methyl ethyl ketone (MEK, 2-Butanone) (CAS Number 78933) is deleted from 

the list of hazardous air pollutants established by 42 U.S.C. 7412(b)(1). [70 FR 75059, 

December 19, 2005]
8

 The substance ethylene glycol monobutyl ether (EGBE, 2-Butoxyethanol) (CAS Number 

111762) is deleted from the list of hazardous air pollutants established by 42 U.S.C. 

7412(b)(1). [69 FR 69325, November 29, 2004]

Particulate matter – Any material, except uncombined water, that exists as a solid or 

liquid in the atmosphere or in a gas stream at standard conditions. 

Transfer efficiency – The amount of coating solids deposited onto the surface or a part 

of a product divided by the total amount of coating solids delivered to the coating 

application system.

Volatile organic compound – any compound of carbon or mixture of carbon compounds 

except the following:

CAS NO. AIR CONTAMINANT NAME

67-64-1 ACETONE

506-87-6 AMMONIUM CARBONATE

124-38-9 CARBON DIOXIDE

630-08-0 CARBON MONOXIDE

---- CARBONIC ACIDS-U

75-68-3 1-CHLORO-1,1-DIFLUOROETHANE (HCFC-142b)

75-45-6 CHLORODIFLUOROMETHANE (HCFC-22)

593-70-4 CHLOROFLUOROMETHANE (HCFC-31)

1615-75-4 1-CHLORO-1-FLUOROETHANE (HCFC-151a)

593-70-4 CHLOROFLUOROMETHANE (HCFC-31)

76-15-3 CHLOROPENTAFLUOROETHANE (CFC-115)

2837-89-0 2-CHLORO-1,1,1,2-TETRAFLUOROETHANE (HCFC-124)

138495-42-8 1,1,1,2,3,4,4,5,5,5-DECAFLUOROPENTANE (HFC 43-10mee)

75-71-8 DICHLORODIFLUOROMETHANE (CFC-12)

1717-00-6 1,1-DICHLORO-1-FLUOROETHANE (HCFC-141b)

507-55-1 1,3-DICHLORO-1,1,2,2,3-PENTAFLUOROPROPANE (HCFC-225cb)

422-56-0 3,3-DICHLORO-1,1,1,2,2-PENTAFLUOROPROPANE (HCFC-225ca)

76-14-2 1,2-DICHLORO 1,1,2,2-TETRAFLUOROETHANE (CFC-114)

354-23-4 1,2-DICHLORO-1,1,2-TRIFLUOROETHANE (HCFC-123a)

75-37-6 1,1-DIFLUOROETHANE (HFC-152a)

75-10-5 DIFLUOROMETHANE (HFC-32)

163702-08-7

2-(DIFLUOROMETHOXYMETHYL)-1,1,1,2,3,3,3-

HEPTAFLUOROPROPANE ((CF3)2CFCF2OCH3)

616-38-6 DIMETHYL CARBONATE
9

CAS NO. AIR CONTAMINANT NAME

74-84-0 ETHANE

163702-06-5

2-(ETHOXYDIFLUOROMETHYL)-1,1,1,2,3,3,3-HEPTAFLUOROPROPANE 

((CF3)2CFCF2OC2H5)

297730-93-9

3-ETHOXY-1,1,1,2,3,4,4,5,5,6,6,6-DODECAFLUORO-2-

(TRIFLUOROMETHYL) HEXANE

(HFE-7500, HFE-s702, T7145, and L-15381)

163702-05-4 1-ETHOXY-1,1,2,2,3,3,4,4,4-NONAFLUOROBUTANE (HFE-7200)

353-36-6 ETHYLFLUORIDE (HFC-161)

375-03-1 1,1,1,2,2,3,3-HEPTAFLUORO-3-METHOXYPROPANE (HFE-7000)

431-89-0 1,1,1,2,3,3,3-HEPTAFLUOROPROPANE (HFC-227ea)

431-63-0 1,1,1,2,3,3-HEXAFLUOROPROPANE (HFC-236ea)

690-39-1 1,1,1,3,3,3-HEXAFLUOROPROPANE (HFC-236fa)

---- METALLIC CARBIDES-U

---- METALLIC CARBONATES-U

74-82-8 METHANE

79-20-9 METHYL ACETATE

75-09-2 METHYLENE CHLORIDE

107-31-3 METHYL FORMATE

163702-07-6 1,1,1,2,2,3,3,4,4-NONAFLUORO-4-METHOXYBUTANE (HFE-7100)

98-56-6 PARACHLOROBENZOTRIFLUORIDE (PCBTF)

406-58-6 1,1,1,3,3-PENTAFLUOROBUTANE (HFC-365mfc)

354-33-6 PENTAFLUOROETHANE (HFC-125)

431-31-2 1,1,1,2,3-PENTAFLUOROPROPANE (HFC-245eb)

460-73-1 1,1,1,3,3-PENTAFLUOROPROPANE (HFC-245fa)

679-86-7 1,1,2,2,3-PENTAFLUOROPROPANE (HFC-245ca)

24270-66-4 1,1,2,3,3-PENTAFLUOROPROPANE (HFC-245ea)

127-18-4 PERCHLOROETHYLENE (TETRACHLOROETHYLENE)

----

PERFLUOROCARBON COMPOUNDS WHICH FALL INTO THESE 

CLASSES:

(1) CYCLIC, BRANCHED, OR LINEAR, COMPLETELY FLUORINATED 

ALKANES;

(2) CYCLIC, BRANCHED, OR LINEAR, COMPLETELY FLUORINATED 

ETHERS WITH NO UNSATURATIONS;

(3) CYCLIC, BRANCHED, OR LINEAR, COMPLETELY FLUORINATED 

TERTIARY AMINES WITH NO UNSATURATIONS; AND

(4) SULFUR CONTAINING PERFLUOROCARBONS WITH NO 

UNSATURATIONS AND WITH SULFUR BONDS ONLY TO CARBON 

AND FLUORINE.

108-32-7 PROPYLENE CARBONATE

---- SILOXANES: CYCLIC, BRANCHED, OR LINEAR COMPLETELY 
10

CAS NO. AIR CONTAMINANT NAME

METHYLATED

540-88-5 TERTIARY-BUTYL ACETATE (T-BUTYL ACETATE)

811-97-2 1,1,1,2-TETRAFLUOROETHANE (HFC-134a)

359-35-3 1,1,2,2-TETRAFLUOROETHANE (HFC-134)

29118-24-9 TRANS-1,3,3,3, TETRAFLUROPROPENE

71-55-6 1,1,1-TRICHLOROETHANE (METHYL CHLOROFORM)

75-69-4 TRICHLOROFLUOROMETHANE (CFC-11)

76-13-1 1,1,2-TRICHLORO-1,2,2-TRIFLUOROETHANE (CFC-113)

306-83-2 1,1,1-TRIFLUORO-2,2-DICHLOROETHANE (HCFC-123)

420-46-2 1,1,1-TRIFLUOROETHANE (HFC-143a)

75-46-7 TRIFLUOROMETHANE (HFC-23)

All definitions are from References 1 through 4.

It should be noted that the EPA definition of VOC does not take into account vapor pressure or 

volatility of the compound. However, this makes a big difference in practice because coating 

resins and plasticizers meet the definition of VOC, yet they do not evaporate. The difference 

between the regulatory definition and what occurs under shop conditions for a coating can be 

reconciled through the use of EPA Test Method 24 (40 CFR 60, Appendix A) which covers the 

determination of coating VOC content, water content, density, volume solids, weight solids, and 

1,1,1-trichloroethane and dichloromethane content. The difference may also be resolved on a 

species-specific basis through the analysis of physical properties as follows:

 Vapor pressure at the maximum process temperature. Compounds with vapor 

pressures less than 0.01 mmHg can usually be assumed not to be emitted as stated in 

the TCEQ Modeling and Effects Review Applicability (MERA) guidance document;

 Boiling point at atmospheric pressure. Compounds with boiling points above 400°F 

can usually be assumed not to be emitted if not heated significantly above room 

temperature in the process; and

 Molecular weight of the compound. VOCs with molecular weights above 200 are 

usually assumed not to be emitted if not heated significantly above room temperature 

in the process.
11

It is also important to recognize that most common coating solvents and solids are also HAPs. 

However, not all VOCs are HAPs, with mineral spirits being one of the more notable differences. 

This provides coating manufacturers an important amount of latitude in the formulation of 

coatings since many NESHAP rules regulate coating HAP content and not VOC content. This 

allows for lower solids content while still meeting the HAP content limits.

COATING BASICS

Coatings are made up of two categories of constituents: solids and solvents. These categories 

can be further subdivided as shown in Figure 1.

Solvents VOC HAPS

Solids

Solids

Figure 1. Coating Solid and Solvent Makeup

The types of ingredients within a coating may be obtained from Material Safety Data Sheets 

(MSDS), technical data sheets, coating vendor technical staff, or from Test Method 24 (40 CFR 

60, Appendix A). In order to complete a set of emission calculations, the use of more than one 

data source is frequently required.

Resins

Pigments

Pigment Extenders

Fillers

Flatting Agents

Rheology Control

Biological Control

UV Inhibitors

Water

Exempt Solvent

Thinners

Diluents

Reducers
12

The coating makeup provides only an inventory list of air contaminants and relative volumes to 

evaluate but it does not describe the fate of the air contaminants as the parts to be coated pass 

through the process. The fate of the solids and solvents depends on the configuration of the 

coating line. Three common scenarios are presented below: 

DIP COATING

 Solvents Solvents

Parts to Wet Dry

be coated Parts Parts

Figure 2. Dip Coating Emission Sources

SPRAY COATING – PARTS DRY IN BOOTH

 Solvents

 Over-spray Solids

Part to Dry

be coated Parts

Over-spray

Solids Fallout

Figure 3. Spray Coating Emission Sources

Dip Tank Parts Drying

 PM Filter

Spray Booth
13

SPRAY COATING – PARTS ARE DRIED OUTSIDE THE

BOOTH OR IN AN OVEN

Solvents

Over-spray Solids

 Solvents Solvents

Parts to Wet Dry

be coated Parts on Conveyor Parts

 Over-spray

 Solids Fallout

Figure 4. Coating Line Emission Sources

Emissions of Solids 

The fate of solids is determined by the application and control methods used. In the first 

example, application techniques with 100 percent transfer efficiency such as dipping, brushing, 

rolling, and flow coating produce no PM emissions because all of the solids that leave the 

applicator remain on the part. In the remaining examples, application techniques with a transfer 

efficiency of less than 100 percent (e.g., spraying), the solids that leave the applicator end up in 

four locations as follows:

 The part to coated;

 The interior of the booth due to overspray and overspray fall out within the booth; 

 The overspray filters; and 

 The portion not captured by the overspray filters exhausted to the atmosphere. 

In order to determine the emissions of the solids to the atmosphere, the amount of solids in the 

first three categories need to be quantified. 

PM Filter

Spray Booth Drying Ovens
14

The geometry of the part and the application equipment determine the transfer efficiency (TE), 

which is a measure of the amount of sprayed coating that is applied to the part. TE may be 

determined through several methods such as estimation from tables or charts, the volume of 

coating applied to a part, or through the weighing of parts and the paint pots. 

Estimation of TE from tables or charts (see References 5 and 6) is the least accurate method and 

is presented as Table 1.

Table 1. Transfer Efficiency as a Function of Application Equipment and Part Geometry

Application Equipment Flat Surface Table Leg 

Surface

Bird Cage 

Air Atomized 50 15 Surface 10

Airless 75-80 10 10

HVLP 65 15 10

Electrostatic Disk 95 90-95 90-95

Electrostatic Airless 80 70 70

Electrostatic Air Atomized 75 65 65

A significant improvement in the estimation of TE can be achieved through the use of the 

volume of coating applied to a part. This can be determined either through the use of wet or dry 

film thickness, coating volume solids content, the surface area of the part, the number of parts 

coated, and accurately weighing the application system (paint pots, hoses and gun) before and 

after the coating is applied.
15

Dry Film Thickness Method

Data Requirements

Surface Area of the Part 43 in2

Dry Film Thickness 0.002 in

Coating Volume Solids Content 0.5 

Coating Density 11.5 lb/gal

Amount of Coating Sprayed 2.87 lb

Number of Parts Coated 150 

Calculate Coating Consumption 

2.87 lb gal = 0.25 gal

11.5 lb

Calculate Transfer Efficiency 

TE = 43 in20.002 in 150 parts gal 100 = 44.7%

0.5 solids 231 in30.25 gal

Wet Film Thickness Method

Data Requirements

Surface Area of the Part 43 in2

Wet Film Thickness 0.004 in

Coating Density 11.5 lb/gal

Amount of Coating Sprayed 2.87 lb

Number of Parts Coated 150
16

Calculate Coating Consumption 

2.87 lb Gal = 0.25 gal

11.5 lb

Calculate Transfer Efficiency 

TE = 43 in20.004 in 150 parts gal 100 = 44.7%

231 in30.25 gal

The best TE estimates can be provided by carefully conducted TE tests on a number of parts. TE 

testing involves accurately weighing the parts and the application system (paint pots, hoses and 

gun) before and after the coating is applied.

Part Weight Change Method

Data Requirements

Coating Solids Content 8.5 lb/gal

Coating Density 11.5 lb/gal

Amount of Coating Sprayed 2.87 lb

Number of Parts Coated 20 

Weight Gain Per Part 0.08 lb

Calculate Coating Solids Sprayed

8.5 lb Gal 2.87 lb = 2.12 lb solids sprayed

Gal 11.5 lb

Calculate Transfer Efficiency

0.08 lb solids 20 parts 100 = 75.4%

Part 2.12 lb solids 
17

For very large parts the method described above can be modified through the use of sheets of 

metal foil applied to the part that are weighed before and after the application of the coating.

The amount of overspray that falls out of the spray booth air stream before entering the 

overspray filter is determined by the application equipment and to a lesser extent the coating 

viscosity. Application equipment with a greater proportion of larger droplets in the spray pattern 

will have a greater portion of the overspray fall out within the booth. Application equipment 

with higher transfer efficiencies such as high volume low pressure (HVLP) or airless spray have 

large numbers of larger droplets compared to air atomized spray equipment. Droplets with a 

diameter of greater than 30 microns do not stay suspended in the air stream for a significant 

amount of time and will fall to the floor of the booth or impact the walls. Therefore, the fraction 

of the paint overspray that will be emitted is the fraction of the droplet sizes that are smaller than 

30 microns in diameter. Determination of the fraction of the droplets smaller than PM10 and PM 

2.5 is also necessary to determine the emission rates in these size ranges. The particle size 

distribution will depend on the type of application equipment used since each type of equipment 

has differing droplet size distributions. Particle size distribution data may be available from

application equipment vendors and from References 8 through 12. The following table may be 

used to estimate PM, PM10, and PM2.5 emission rates for both enclosed and outdoor coating 

operations.

Table 2 Particle Size Distribution as a Function of Application Equipment 

Application Equipment 

Type

Droplet Fraction Greater 

than PM30

Droplet Fraction Greater 

than PM10

Droplet Fraction Greater 

than PM2.5

Air Atomized 0.81 0.94 0.99

Airless 0.9856 0.9987 0.9999

HVLP 0.90 0.90 0.90

Overspray filters are used in nearly all spray booths to control PM emissions and the efficiency 

of the filter system (dry filters or, in some older booths, water wash) is usually available from the 
18

filter system vendor. Overall PM control efficiencies (PM30 and smaller) may be determined by 

ASHRAE Method 52.1. Control efficiencies for PM10 and PM 2.5 may be determined by 

ASHRAE Method 52.2. Filter media evaluated by this method will have a minimum efficiency 

removal value (MERV) provided. To be assigned a specific MERV value, the filter media must 

achieve a minimum composite average particle size removal efficiency minimum efficiency in 

three particle size ranges. The size ranges are 0.3 - 1.0, 1.0 - 3.0, and 3.0 to 10.0 microns. If the 

vendor provides a MERV for the filter media, the efficiencies for the various particle sizes may 

be determined using the MERV chart. 

Table 3 Composite Average Particle Size Removal Efficiency Requirements for a Specific 

MERV

Composite Average Particle Size Removal 

Efficiency (%) in Size Range (μm) -

ANSI/ASHRAE Standard 52.2-2007 Contaminants Typically 

MERV 0.3–1.0 1.0–3.0 3.0–10.0 Controlled Typical Applications

1 — — <20 Particles >10.0 μm: 

pollens, dust mites, 

textile/carpet fibers

Minimum filtration; 

residential buildings 2 — — <20

3 — — <20

4 — — <20

5 — — 20–35 Particles 3 - 10.0 μm: 

mold, spores, cement dust

Most commercial and 

better residential buildings

6* — — 35–50

7 — — 50–70

8 — — >70

9 — <50 >85 Particles 1.0 - 3.0 μm: 

Legionella, lead dust, coal 

dust, auto emmissons

Superior residential and

better commercial 

buildings 10 — 50–65 >85

11 — 65–80 >85

12 — >80 >90

13 <75 >90 >90 Particles 0.3 - 1.0 μm: all 

bacteria, most tobacco 

smoke, droplet nuclei, 

most smoke

Hospital inpatient and 

general surgery; superior 

commercial buildings 14 75–85 >90 >90

15 85–95 >90 >90

16 >95 >95 >95

IEST Standards

17 >99.97 on 0.30 μm particles, IEST Type A Particles <0.3 μm (viruses, Cleanrooms and 
19

18 >99.99 on 0.30 μm particles, IEST Type C radon progeny, carbon 

dust)

pharmaceutical 

manufacturing 19 >99.999 on 0.30 μm particles, IEST Type D

20 >99.9999 on 0.10–0.20 μm particles, IEST Type 

F 

* Mimimum requirement under ASHRAE standard 62.1 (Ventilation for Acceptable Indoor Air Quality)

Source: Adapted with permission from ANSI/ASHRAE Standard 52.2-2007: Method of Testing General Ventilation 

Air-Cleaning Devices for Removal Efficiency by Particle Size. Atlanta, GA: American Society of Heating, 

Refrigerating, and Air-Conditioning Engineeers, Inc. 2007 © American Society of Heating, Refrigerating and AirConditioning Engineers, Inc., www.ashrae.org

The control efficiency of the system for the various particle size ranges will be determined by 

limits on offproperty concentrations of the PM species, applicable rules for ambient PM, PM10

and smaller and PM2.5 and smaller concentrations, applicable state and federal rules and air 

permit requirements. As a result, emission rates must be determined for three particle size 

ranges; PM, PM10 and smaller and PM2.5 and smaller.

Emissions of Solvents

All solvents are ultimately lost to the atmosphere. The difficult part is determining the emission 

distribution or how much solvent is lost to the atmosphere at different steps in the process. The 

emission distribution is dependent on the following:

 Transfer efficiency (TE);

 The solvent species and their relative amounts in the coating;

 The speed at which the parts are removed from the booth after spraying;

 The amount of time the parts are allowed to dry outside of the booth in a drying area 

or on a conveyor; and

 The use of drying ovens.

TE affects the distribution of solvent emissions because all of the solvents contained in the 

overspray will be emitted from the spray booth based on the assumption of 100 percent capture 
20

efficiency. With higher TE values, less overspray will occur in the booth to generate solvent 

emissions.

The solvents used in the coating have the greatest effect on the distribution of solvent emissions. 

Coatings such as lacquers that have “fast” solvents will have the majority of the solvent 

evaporate or “flashoff” in the booth. Other coatings such as water based epoxies that have a 

greater proportion of “slow” solvents will have a lesser portion of the solvents flashoff in the 

booth and a greater proportion flashoff outside of the booth provided that the residence time in 

the booth is the same.

As noted above, the residence time of the parts in the booth, in drying areas, flashoff tunnels, and 

on conveyors will further determine the solvent emission distribution. The longer the parts 

remain in any specific segment of a coating line, the greater the solvent emissions will be for that 

segment. The fraction of the solvents emitted in any one segment of the coating line may be 

estimated through the use of flashoff curves or through testing on the coating line or in a 

laboratory where coating line conditions can be accurately duplicated. 

Generic flashoff curves provide the least accurate estimate of solvent emission distributions and 

an example of flashoff curves from Reference 5 is presented in Figure 5.
21

Figure 5. Coating Flashoff Curves

The flashoff curves can be used to estimate the solvent emission distribution for the type of 

coating in use based on the time that the parts remain in any segment of the coating line. For 

example, an epoxy coated part will have lost approximately 30 percent of the solvent upon 

exiting the booth at 2 minutes after spraying. The same part will have lost an additional 9 

percent of the solvent after 8 minutes on the conveyor (39% total loss – 30% loss in the booth).

Increased accuracy in the solvent emission distribution can be achieved through the use of either 

laboratory testing or testing on the coating line. For laboratory testing, coated parts are weighed 

at specific time intervals that correspond to the change in line segments. The resulting weight 

change at each time interval corresponds to the solvent loss. Similarly, testing on the actual 
22

coating line involves weighing parts at each process transition and recording the weight change 

to determine the solvent loss for the specific segment of the coating line. 

If an oven is used in the process, the parts are usually dry upon exiting the oven. In the case of 

dry parts, the solvent loss in the oven will equal the remaining amount of solvent in the coating 

on the part. For example, if 39 percent of the solvent is lost in the booth and on the conveyor, 61 

percent of the solvent is lost in the oven (100% - 39% lost in the booth and conveyor). 

CLASSIFICATION OF CALCULATIONS AND SUMMARY OF REQUIRED DATA 

AND DATA SOURCES

Emission calculations for surface coating fall into two broad categories as follows:

 Concentration units; and

 Mass units.

Concentration units, such as lb VOC/gallon, most frequently appear in rules (RACT, NSPS, 

NESHAP etc.), new source review (NSR) permits, and Title V permits and are designed to 

reduce emissions from existing sources and limit emissions from new sources. These standards 

are written for specific operations in specific industries to achieve emission reductions over 

current practices.

Mass units, such as lb/hr or tons/yr, are needed to complete TCEQ NSR permit applications, 

emission inventories, and emission fee calculations, and are used as inputs into atmospheric 

dispersion models. The dispersion models are used to demonstrate compliance with the National 

Ambient Air Quality Standards (NAAQS) and TCEQ state property line standards for particulate 

matter and H2S, as well as providing the off-property concentrations of all species to be emitted 

by the facility to demonstrate that the facility emissions will not be detrimental to public health. 

The data required to complete the calculation depends on the units that the standard or limit 

contains. The most common units and the required data appear in Tables 6 through 10. 
23

TABLE 4

SURFACE COATING CALCULATIONS - SOLVENT EMISSIONS 

DATA REQUIREMENTS AND DATA SOURCES

Concentration Limits 

lb VOC/gal of coating lb VOC/gal solids lb VOC/gal solids applied 

Coating Data Required Units Data Source Units Data Source Units Data Source

Coating Consumption

lb/gal MSDS lb/gal MSDS lb/gal MSDS

Multiple Component Mixing 

Ratio

lb/gal MSDS lb/gal MSDS lb/gal MSDS

Thinning Ratio

lb/gal MSDS lb/gal MSDS lb/gal MSDS

Coating Density

lb/gal MSDS lb/gal MSDS lb/gal MSDS

Coating/Component VOC 

Content

lb/gal MSDS lb/gal MSDS lb/gal MSDS

Coating Water Content 

lb/gal MSDS lb/gal MSDS lb/gal MSDS

Coating Exempt Solvent 

Content 

lb/gal MSDS lb/gal MSDS lb/gal MSDS

Coating Volume VOC 

Content 

Percent MSDS/Technical Data Percent MSDS/Technical Data Percent MSDS/Technical Data

Sheet/Vendor Sheet/Vendor Sheet/Vendor

Thinner Density

lb/gal MSDS lb/gal MSDS lb/gal MSDS

VOC Control Efficiency

Percent

Control Equipment 

Vendor Percent

Control Equipment 

Vendor Percent

Control Equipment 

Vendor

Coating Volume Solids 

Content 

Percent MSDS/Technical Data Percent MSDS/Technical Data Percent MSDS/Technical Data

Sheet/Vendor Sheet/Vendor Sheet/Vendor

Transfer Efficiency

NA NA Percent

Tables/Calculation/ 

Testing
24

TABLE 5

SURFACE COATING CALCULATIONS - SOLVENT EMISSIONS 

DATA REQUIREMENTS AND DATA SOURCES

Mass Units 

lb/hr tons/yr

Coating Data Required Units Data Source Units Data Source

Coating Consumption

gal/hr Plant Production Data gal/yr Plant Production Data

Multiple Component Mixing Ratio

None MSDS/Technical Data None MSDS/Technical Data

Sheet/Vendor Sheet/Vendor

Thinning Ratio

None MSDS/Technical Data None MSDS/Technical Data

Sheet/Vendor Sheet/Vendor

Coating Density

lb/gal MSDS lb/gal MSDS

Coating/Component VOC Content

lb/gal MSDS lb/gal MSDS

Coating Exempt Solvent Content 

lb/gal MSDS lb/gal MSDS

Thinner Density

lb/gal MSDS lb/gal MSDS

Thinner VOC Content

lb/gal MSDS lb/gal MSDS

Thinner Exempt Solvent Content

lb/gal MSDS lb/gal MSDS

VOC Emission Distribution

Percent Flashoff Curves or Testing Percent 

Flashoff Curves or 

Testing

VOC Control Efficiency

Percent Control Equipment Vendor Percent

Control Equipment 

Vendor 
25

TABLE 6

SURFACE COATING CALCULATIONS - SOLIDS EMISSIONS 

DATA REQUIREMENTS AND DATA SOURCES

Mass Units 

lb/hr tons/yr

Coating Data Required Units Data Source Units Data Source

Coating Consumption

gal/hr Plant Production Data gal/yr Plant production data

Multiple Component Mixing Ratio

None MSDS/Technical Data None MSDS/Technical Data

Sheet/Vendor Sheet/Vendor

Thinning Ratio

None MSDS/Technical Data None MSDS/Technical Data

Sheet/Vendor Sheet/Vendor

Coating Density

lb/gal MSDS lb/gal MSDS

Thinner Density

lb/gal MSDS lb/gal MSDS

Coating/Component Solids Content 

lb/gal MSDS lb/gal MSDS

Transfer Efficiency

Percent Tables/Calculation/Testing Percent Tables/Calculation/Testing

Filter Efficiency

Percent Control Equipment Vendor Percent Control Equipment Vendor 

Fall Out

Percent Tables/Vendor Percent Tables/Vendor
26

TABLE 7

SURFACE COATING CALCULATIONS - SOLVENT SPECIES EMISSION RATES 

DATA REQUIREMENTS AND DATA SOURCES

Species Mass Emission Rates

lb/hr tons/yr

Coating Data Required Units Data Source Units Data Source

Coating Consumption

gal/hr Plant Production Data gal/yr Plant production data

Multiple Component Mixing Ratio

None MSDS/Technical Data None MSDS/Technical Data

Sheet/Vendor Sheet/Vendor

Thinning Ratio

None MSDS/Technical Data None MSDS/Technical Data

Sheet/Vendor Sheet/Vendor

Coating Density

lb/gal MSDS lb/gal MSDS

Coating/Component Species

Percent MSDS Percent MSDS

Thinner Density

lb/gal MSDS lb/gal MSDS

Thinner Species

Percent MSDS Percent MSDS

VOC Emission Distribution

Percent Flashoff Curves or Testing Percent Flashoff Curves or Testing

VOC Control Efficiency

Percent Control Equipment Vendor Percent Control Equipment Vendor 
27

TABLE 8

SURFACE COATING CALCULATIONS - SOLIDS SPECIES EMISSION RATES 

DATA REQUIREMENTS AND DATA SOURCES

Species Mass Emission Rates

lb/hr tons/yr

Coating Data Required Units Data Source Units Data Source

Coating Consumption

gal/hr Plant Production Data gal/yr Plant production data

Multiple Component Mixing Ratio

None MSDS/Technical Data None MSDS/Technical Data

Sheet/Vendor Sheet/Vendor

Thinning Ratio

None MSDS/Technical Data None MSDS/Technical Data

Sheet/Vendor Sheet/Vendor

Coating Density

Lb/gal MSDS lb/gal MSDS

Thinner Density

Lb/gal MSDS lb/gal MSDS

Coating/Component Species 

Lb/gal MSDS lb/gal MSDS

Transfer Efficiency

Percent Tables/Calculation/Testing Percent Tables/Calculation/Testing

Filter Efficiency

Percent Control Equipment Vendor Percent Control Equipment Vendor 

Fall Out

Percent Tables/Vendor Percent Tables/Vendor

CALCULATION APPROACH 

The actual emission calculations for each set of units may be determined either by hand or by 

using a computer. Hand methods are impractical for facilities that use large numbers of coatings 

or have a large number of emission sources. However, hand calculations illustrate the 

calculation approach for each set of units and are presented below.
28

Coating As-Applied VOC Content

Single Component Coating 

Data Requirements

Coating VOC content from MSDS or technical data sheet

Since the coating is not mixed with any thinners or any other components the as-applied VOC 

content will be as stated.

Single Component Coating with Thinner

Data Requirements 

Coating VOC Content 2.8 lb VOC/gal

Thinner VOC Content 7.3 lb VOC/gal

Thinning Ratio 10 : 1

10 Parts Coating 5 gal

1 Part thinner 0.5 gal

11 Parts Mixed Coating 5.5 gal

Calculate VOC Content 

2.8 lb VOC 5 gal + 7.3 lb VOC 0.5 gal =17.65 lb VOC

Gal gal

17.65 lb VOC =3.20 lb VOC/gal coating

5.5 gal
29

Multiple Component Coating

Data Requirements 

Part A VOC Content 2.8 lb VOC/gal

Part B VOC Content 1.2 lb VOC/gal

Mixing Ratio 2 : 1

2 Parts Part A 1 gal

1 Part Part B 0.5 gal

3 Parts Mixed Coating 1.5 gal

Calculate VOC Content 

2.8 lb VOC 1 gal + 1.2 lb VOC 0.5 gal =3.4 lb VOC

Gal gal

3.4 lb VOC =2.26 lb VOC/gal coating

1.5 gal
30

Multiple Component Coating with Thinner 

Data Requirements 

Part A VOC Content 2.8 lb VOC/gal

Part B VOC Content 1.2 lb VOC/gal

Thinner VOC Content7.3 lb VOC/gal

Mixing Ratio 2 : 1

2 Parts Part A 1 gal

1 Part Part B 0.5 gal

3 Parts Mixed Coating 1.5 gal

Thinning Ratio 10 : 1

10 Parts Coating 1.5 gal

1 Part thinner 0.15 gal

11 Parts Mixed Coating 1.65 gal

Calculate VOC Content 

2.8 lb VOC 1 gal + 1.2 lb VOC 0.5 gal + 7.3 lb VOC 0.15 gal =4.49 lb VOC

Gal gal gal

4.49 lb VOC =2.72 lb VOC/gal

1.65 gal

Coating VOC Content - Less Water and Exempt Solvent 

In addition to calculating coating VOC content as applied on a per gallon of coating basis, many 

State and federal rules require that the as-applied coating VOC content be determined on a per 

gallon of coating basis, less water and exempt solvent. This also requires that the volume of 

water and exempt solvent (gallons) be known for the coating. 
31

Data Requirements

Coating VOC Content 2.8 lb VOC/gal

Coating Water Content 1.0 lb water/gal

Water Density 8.34 lb/gal

Coating Exempt Solvent Content 0.5 lb ES/gal

Exempt Solvent Density 6.64 lb/gal

Calculate Coating Volume Water and Exempt Solvent

1.0 lb Water Gal = 0.12 gal

Gal 8.34 lb

0.5 lb ES Gal = 0.075 gal

Gal 6.64 lb

Calculate Coating VOC Content

Coating VOC Content (lb) = lb VOC/gal coating (less Water and ES)

1 (gal) – Coating Water Volume (gal) - Coating ES Volume (gal)

2.8 lb VOC/gal = 2.8 lb VOC = 3.47 lb VOC/ gal coating (less Water and ES)

1 gal - 0.12 gal - 0.075 gal 0.805 gal

Coating VOC Content per Gallon of Solids

Some State and federal rules contain an alternate standard that requires the as-applied coating 

VOC content be determined on a per gallon of solids basis. This set of units requires that the 

volume of VOC, water, and exempt solvent (gallons) be known for the coating.
32

Data Requirements

Coating VOC Content 2.8 lb VOC/gal

Solvent System Density 7.1 lb/gal 

Coating Water Content 1.0 lb water/gal

Water Density 8.34 lb/gal

Coating Exempt Solvent Content 0.5 lb ES/gal

Exempt Solvent Density 6.64 lb/gal

Calculate Coating Volume VOC, Water and Exempt Solvent 

2.8 lb VOC gal = 0.394 gal

Gal 7.1 lb

1.0 lb Water gal = 0.12 gal

Gal 8.34 lb

0.5 lb ES gal = 0.075 gal

Gal 6.64 lb

Calculate Coating VOC Content

Coating VOC Content (lb) = lb VOC/gal solids

1 (gal) - Coating VOC Volume (gal) - Coating Water Volume (gal) - Coating ES Volume (gal)

2.8 lb VOC/gal = 2.8 lb VOC = 6.81 lb VOC/ gal solids

1 gal - 0.394 gal - 0.12 gal - 0.075 gal 0.411 gal

Coating VOC Content per Gallon of Solids Applied

The final set of VOC concentration units are commonly seen in NSPS standards and have units 

of lb VOC/gal solids applied. This type of standard allows for greater compliance flexibility due 

to allowing transfer efficiency to be taken into consideration. In other words, a higher VOC 
33

content coating (lb VOC/gal coating) can be used to achieve compliance with the standard as 

long as a high transfer efficiency application system is used.

Data Requirements

Coating VOC Content 2.8 lb VOC/gal

Solvent System Density 7.1 lb/gal 

Coating Water Content 1.0 lb water/gal

Water Density 8.34 lb/gal

Coating Exempt Solvent Content 0.5 lb ES/gal

Exempt Solvent Density 6.64 lb/gal

Transfer Efficiency 0.60

Calculate Coating Volume VOC, Water and Exempt Solvent 

2.8 lb VOC Gal = 0.394 gal

Gal 7.1 lb

1.0 lb Water Gal = 0.12 gal

Gal 8.34 lb

0.5 lb ES Gal = 0.075 gal

Gal 6.64 lb

Calculate Coating VOC Content 

Coating VOC Content (lb) = lb VOC/gal solids applied

1 (gal) - Coating VOC Volume (gal) - Coating Water Volume (gal) -

Coating ES Volume (gal) TE

2.8 lb VOC/gal = 2.8 lb VOC = 11.35 lb VOC/ gal solids applied

1 gal – 0.394 gal - 0.12 gal - 0.075 gal 0.6 0.411 gal 0.6
34

Coating HAP Content - Pounds Organic HAP per Pound of Coating Solids 

The concentration limits in the National Emission Standard for Hazardous Air Pollutants 

(NESHAPs) under 40 CFR Part 63 (MACT) for some coating operations contain limits in units 

of Lb HAP/Lb of coating solids. 

Data Requirements

Coating Density 11.5 lb/gal

Coating VOC Content 3.5 lb VOC/gal

Coating PM Content 8.0 lb PM/gal

Coating HAP Content 2.0 lb HAP/gal

Calculate Coating HAP Content 

2.0 lb HAP Gal = 0.25 lb HAP/lb PM

Gal 8.0 lb PM
35

Coating Mass Emission Rates

Emission Rates – Parts Dry in the Spray Booth

Data Requirements

Coating VOC Content 3.5 lb VOC/gal

Coating PM Content 8.0 lb PM/gal

Daily Coating Consumption 6.0 gal

Spray Time 3.0 hr

Annual Coating Consumption 4750 gal/yr

Transfer Efficiency 0.60

Filter Efficiency- Booth 99.00%

Minimum Efficiency Removal Value 14

Filter Efficiency 3.0- 10.0 microns 90.00%

Filter Efficiency 1.0 - 3.0 microns 90.00%

PM Fallout PM30 98.56%

PM Fallout PM10 99.87%

PM Fallout PM2.5 99.99%

Calculate Short Term VOC Emission Rate

3.5 lb VOC 6.0 gal = 7.0 lb VOC/hr

Gal 3 hr

Calculate Short Term PM30 Emission Rate

8.0 lb PM 6.0 gal 1 - 0.6 1 - 0.99 1 - 0.9856 = 0.0009 lb PM30/hr

Gal 3 hr
36

Calculate Short Term PM10 Emission Rate

8.0 lb PM 6.0 gal 1 - 0.6 1 - 0.90 1 - 0.9987 = 0.0008 lb PM10/hr

Gal 3 hr

Calculate Short Term PM2.5 Emission Rate

8.0 lb PM 6.0 gal 1 - 0.6 1 - 0.90 1 - 0.9999 = 0.0001 lb PM2.5/hr

Gal 3 hr

Calculate Annual VOC Emission Rate

3.5 lb VOC 4750 gal 1 ton = 8.31 ton VOC/yr

gal Yr 2000 lb

Calculate Annual PM30 Emission Rate

8.0 lb PM 4750 gal 1 - 0.6 1 - 0.99 1 - 0.9856 1 ton = 0.0011 ton PM30/yr

Gal Yr 2000 lb

Calculate Annual PM10 Emission Rate

8.0 lb PM 4750 gal 1 - 0.6 1 - 0.90 1 - 0.9987 1 ton = 0.0010 ton PM10/yr

Gal Yr 2000 lb

Calculate Annual PM2.5 Emission Rate

8.0 lb PM 4750 gal 1 - 0.6 1 - 0.90 1 - 0.9999 1 ton = 0.0001 ton PM2.5/yr

Gal Yr 2000 lb
37

Emission Rates – Parts Dry on the Conveyor and Oven

Coating VOC Content 3.5 lb VOC/gal

Daily Coating Consumption 6.0 gal

Spray Time 3.0 hr

Annual Coating Consumption 4750 gal/yr

Transfer Efficiency 0.60

Solvent Loss in Booth 0.30

Solvent Loss on Conveyor 0.09

Solvent Loss in the Oven 0.61

Calculate Total Short Term VOC Emissions for the Coating Line

3.5 lb VOC 6.0 gal = 7.0 lb VOC/hr

Gal 3 hr
38

Calculate Short Term VOC Emission Rate for Each Coating Line Segment

Spray Booth

Part Overspray

TE

Booth 

Flashoff 1-TE

7.0 lb VOC 0.60 0.30 + 7.0 lb VOC 1 - 0.6 = 4.06 lb VOC/hr

hr hr

Conveyor

TE Conveyor Flashoff

7.0 lb VOC 0.60 0.09 = 0.37 lb VOC/hr

hr

Drying Oven

TE

Oven 

Flashoff

7.0 lb VOC 0.60 0.61 = 2.56 lb VOC/hr

hr

Calculate Total Annual VOC Emissions for the Coating Line

3.5 lb VOC 4750 gal 1 ton = 8.31 ton VOC/yr

Gal Yr 2000 lb
39

Calculate Annual VOC Emission Rate for Each Coating Line Segment

Spray Booth

Part Overspray

TE Booth Flashoff 1-TE

8.31 ton VOC 0.60 0.30 + 8.31 ton VOC 1 – 0.6 = 4.81 ton VOC/yr

yr yr

Conveyor

TE Conveyor Flashoff

8.31 ton VOC 0.60 0.09 = 0.45 ton VOC/yr

yr

Drying Oven

TE

Oven 

Flashoff

8.31 ton VOC 0.60 0.61 = 3.04 ton VOC/yr

yr

Only VOC emission rates are calculated in this example since it is assumed that all of the PM 

emissions occur within the booth and the emission calculation will be the same as in the previous 

example. Most spray booths that have a face velocity of 100 – 200 ft/min will achieve 100 

percent capture of both PM and VOC emissions. Actual painting is not the only source of 

emissions in these examples. Cleanup solvent can make a significant contribution to the total 

annual solvent emissions for the facility. Because cleanup and coating application cannot occur 

simultaneously, hourly cleanup emission rates should be calculated separately. The short-term 
40

permit limit will be the higher of the two emission rates. Cleanup emission rates should be 

determined using the same methodology as used in the VOC emission rate calculations noted 

above with consideration given to the amount of spent wash solvent recovered during cleanup.

Coating Species Mass Emission Rates

Data Requirements

Coating Density 11.5 lb/gal

Daily Coating Consumption 6.0 gal

Spray Time 3.0 hr

Annual Coating Consumption 4750 gal/yr

Transfer Efficiency 0.60

Filter Efficiency 0.99

Fall Out Factor 0.9856

Mixed Coating Formulation 

Coating Weight Constituent HAP

Constituent CAS No. Fraction Type (P/V/ES) (Y/N)

Methyl Ethyl Ketone 78-93-3 0.20 V Y

Acetone 67-64-1 0.05 ES N

Methanol 67-56-1 0.10 V Y

VM&P Naphtha 8032-32-4 0.05 V N

Strontium Chromate 6/2/89 0.10 P Y

Titanium Dioxide 13463-67-7 0.15 P Y

Iron Oxide 1332-37-2 0.05 P N

Epoxy Resin NA 0.30 P N
41

Calculate Short Term Species Emission Rates

Volatile Species 

11.5 lb 6.0 gal Wt. Fraction = 23.0 Weight Fraction lb/hr

Gal 3 hr

Coating Weight Weight Emission 

Constituent Fraction Fraction lb/hrRate (lb/hr)

Methyl Ethyl Ketone 0.20 23.0 4.60

Acetone 0.05 23.0 1.15

Methanol 0.10 23.0 2.30

VM&P Naphtha 0.05 23.0 1.15

Particulate Species

1 - TE 1 - FE 1 - FO

11.5 lb 6.0 gal

Wt. 

Fraction 1 - 0.60 1 - 0.99 1 - 0.9856 = 0.0013 Weight Fraction lb/hr

gal 3 hr

Coating Weight Weight Emission 

Constituent Fraction Fraction lb/hrRate (lb/hr)

Strontium Chromate 0.10 0.0013 0.0001

Titanium Dioxide 0.15 0.0013 0.0002

Iron Oxide 0.05 0.0013 0.0001

Epoxy Resin 0.30 0.0013 0.0004

Calculate Annual Species Emission Rates

Volatile Species 

11.5 lb 4750 gal 1 Ton Wt. Fraction = 27.3 Weight Fraction ton/yr

gal Yr 2000 lb
42

Coating Weight Weight Emission 

Constituent Fraction Fraction ton/yrRate (ton/yr)

Methyl Ethyl Ketone 0.20 27.3 5.46

Acetone 0.05 27.3 1.36

Methanol 0.10 27.3 2.73

VM&P Naphtha 0.05 27.3 1.36

Particulate 

Species

1 - TE 1 - FE 1 - FO

11.5 lb 4750 gal 1 Ton

Wt. 

Fraction 1 - 0.60 1 - 0.99 1 - 0.9856 = 0.0016 Weight Fraction ton/yr

gal Yr 2000 lb

Coating Weight Weight Emission 

Constituent Fraction Fraction ton/yrRate (ton/yr)

Strontium Chromate 0.10 0.0016 0.00016

Titanium Dioxide 0.15 0.0016 0.00024

Iron Oxide 0.05 0.0016 0.00008

Epoxy Resin 0.30 0.0016 0.00048

The emission distribution for the individual volatile species can be determined using the solvent 

loss fractions (flashoff fractions) used in the previous example. 

Calculation of HAPS 

Since the adoption of the Federal Clean Air Act Amendments of 1990, an additional set of 

calculations may be necessary to determine the emission rate of hazardous air pollutants (HAPs). 

A number of the National Emission Standards for Hazardous Air Pollutants (NESHAPs) under 

40 CFR 63 apply to surface coating operations and contain concentration limits (lb HAP/gal) that 
43

affected facilities are required to certify compliance. In addition, the applicability of these rules 

and the applicability of Title V operating permits under 40 CFR 70 may also be triggered solely 

by HAP emissions if they exceed 10 tpy for any individual HAP and 25 tpy in the aggregate for a 

site.

Fortunately, HAP emissions can be calculated using the same methods as VOC and speciated 

emissions. The only changes to the methods is simply the substitution of coating HAP content 

for VOC content to determine compliance with concentration limits. To determine if the 10/25 

tpy thresholds are exceeded, the speciated emission calculations need only be completed for the 

HAP species (see definitions) and compared to the 10 tpy threshold for any individual HAP 

species and summed to determine if the total exceeds 25 tpy. 

Addition of Emission Controls for Solvents

All of the coating scenarios evaluated above do not consider the use of solvent emission controls. 

Controls are generally required for three reasons as follows:

 The emission standard in federal, state or local rules cannot be met;

 To meet the requirements of Best Available Control Technology (BACT) in federal, 

and TCEQ permits; and

 To provide acceptable off property concentrations of the various solvent species to 

insure that there will be no adverse effects on public health.

Emission controls for surface coating can either be process controls or add-on controls. Process 

controls involve changing the basic process to provide greater efficiency in the application of 

coatings and in the use of solvents. Process controls typically consist of increasing transfer 

efficiency (less coating is used per part) and through the use of high solids coatings (less coating 

and solvent used per part). Add-on controls provide significant emission reductions as long as 

the unit is used to control the correct portion of the coating line (usually the spray booths and 

flashoff tunnel) and the emission capture efficiency is high. The most common types of 
44

emission controls are thermal oxidizers in one of many configurations or carbon adsorption 

systems. Carbon adsorption systems can work nearly as well as thermal systems provided the 

emission species are well known and do not change over time.

The emission reductions for process controls can be determined through substituting the revised 

transfer efficiencies and coating solvent contents into the emission calculation methods covered 

previously. For add-on controls, the emission calculation methods need to be modified through 

the use of an additional term that includes the control efficiency (CE) of the add-on control 

equipment as follows:

Addition of Emission Controls

Emission Rate 1 - CE =

Emission Rate 1 - 0.98 = Emission Rate X 0.02

This calculation approach works for either concentration units or mass units without 

modification.

AUTOMATION OF EMISSION CALCULATIONS

The emission calculation methods previously described present an orderly approach for hand 

calculations but are still far too cumbersome to be used on a daily basis for compliance 

demonstrations or for use in permit applications. Fortunately, spreadsheets and databases can be 

used to simplify the process and reduce the amount of repetitive data entry through the use of 

tables that store specific types of information as follows:

 Coating and solvent properties such as density, VOC content, mix ratios, species, and 

type, etc.;
45

 Configuration of the facility such as number of booths, filter efficiencies, and VOC 

control efficiencies;

 Dynamic data that includes transfer efficiency and changes in flashoff due to changes 

in coatings and conveyor speed; and

 Daily data that includes the amount of each coating and solvent mixed, applied in 

each booth or coating line, and transferred to waste.

This type of approach allows the data to be easily updated, sorted by type of product (polyester, 

epoxy etc.), type of air contaminant (P, V, ES, HAP), date, or booth. As can be seen from the 

emission calculation examples, a great deal of data is common between the various emission 

standard and the software can draw from common tables to produce a variety of preformatted 

reports to demonstrate regulatory compliance or regulatory applicability. In addition, emission 

calculation automation can also provide management with useful information on production 

costs such as the cost of coating per part, comparison of the amount of coating used by different 

crews on the same parts, and provide opportunities for process improvement and reductions in 

operating costs.

CONCLUSIONS

Emission calculations for surface coating facilities have become more important than ever for 

facilities to demonstrate compliance with regulatory and permit limits as well as initially setting 

permit emission limits. This task can be simplified if accurate coating and facility data is 

collected through a partnership with coating and equipment vendors, facility production 

operations, and facility management. Understanding how to collect this data and calculate both 

concentration and mass emission rates will allow the environmental staff to more easily prepare 

permit applications, and upon issuance of the permit more easily demonstrate compliance with 

permit and other regulatory emission limits. 
46

REFERENCES

1. Clean Air Act, §112[42 USC 7142] National Emission Standard for Hazardous Air 

Pollutants, §112(b) List of Pollutants

2. Texas Commission on Environmental Quality – 2005 Emission Inventory Guidelines –

2005. Document No. RG-360_05, December 2005 (available online at: 

http://www.tceq.state.tx.us/comm_exec/forms_pubs/pubs/rg/rg-360_05/rg360_05_1390103.pdf ).

3. Texas Commission on Environmental Quality – General Air Quality Rules, 30 TAC 

§101.1, June 15, 2005 (available online at: 

http://www.tceq.state.tx.us/assets/public/legal/rules/rules/pdflib/101a.pdf ).

4. Texas Commission on Environmental Quality – Control of Air Pollution from Volatile 

Organic Compounds, 30 TAC §115.10 and 30 TAC §115.420, May 5, 2005 (available 

online at: http://www.tceq.state.tx.us/assets/public/legal/rules/rules/pdflib/115a.pdf and 

http://www.tceq.state.tx.us/assets/public/legal/rules/rules/pdflib/115e.pdf ).

5. Air Pollution Engineering Manual, AP-40. 2nd ed., J. .A. Danielson, Ed.; Air Pollution 

Control District of Los Angeles, Environmental Protection Agency, Office of Air and 

Water Programs, Office of Air Quality Planning and Standards, Research Triangle Park, 

NC, May 1973 

6. Air Pollution Engineering Manual. Anthony J. Buonicore and Wayne T. Davis, Ed., Air 

and Waste Management Association, 1992, p. 362

7. Texas Natural Resource Conservation Commission – Air Permit Technical Guidance for 

Coating Sources: Surface Coating Operations, April 2001

8. Calculations on particle size paints prepared by D.T. Emery of Phillips Petroleum 

Company in Bartlesville, Oklahoma, January 1993;
47

9. Droplet distribution information prepared by Dan Carroll of Coltec Industries in Des 

Moines, Iowa, November 1992;

10. Determination of Particle Size Distributions for Airless Spray prepared by K.C. Kwok, 

Ph.D. for Rescar Inc. of Downers Grove, Illinois, January 1994; 

11. IWATA Test Report supplied by Glen Nelson, Project Manager for Binks Manufacturing 

Company of Franklin Park, Illinois, July 1993; and

12. CORROSION 95 - Paper No. 634, Cost Effective Solutions Today and Beyond 2000 with 

Supercritical Fluid Technology prepared by R.J. Woods and D.C. Busby, Union Carbide 

Corporation, South Charleston, WV.