United States Office of Air Quality EPA-450/2-78-015 

Environmental Protection Planning and Standards OAQPS No. 1.2-1 01 

Agency Research Triangle Park NC 2771 1 June 1978 

Air 

Guideline Series CW.TING

OTHER METAL 

P.P- 42 

Section 4.2.7.9 

Reference Number 

Control of Volatile 

Organic Emissions 

trom tx~stmg 

Stationary Sources -

Volume VI: Surface 

Coating of 

Miscellaneous Metal 

Parts and Products 
EPA-450/2-78-015 

(OAOPS NO.1.2-101) 

CONTROL OF VOLATILE ORGANIC 

EMISSIONS FROM EXISTING 

STATIONARY SOURCES 

VOLUME VI: SURFACE COATING 

OF MISCELLANEOUS METAL PARTS 

AND PRODUCTS 

Emissions Standards and Engineering Division 

Chemical and Petroleum Branch 

U.S. ENVIRONMENTAL PROTECTION AGENCY 

Office of Air, Noise and Radiation 

Office of Air Quality Planning and Standards 

Research Triangle Park, North Carolina 2771 1 

June 1978 
PREFACE 


This document is one of a series designed to inform Regional, State, 

and local air pollution control agencies of techniques available for 

reducing emissions of volatile organic compounds (VOC) from -existing 

stationary sources. This document deals with the surface coating of 

miscellaneous metal parts and products, and is intended to provide 

guidance on VOC emission control for job shop and original equipment 

manufacturing (OEM) industries which apply coatings on metal substrates 

which have not been the subject of more specific previous documents 

in this series. Reports have already been published which identify control 

options for the following industries: can, coil, automobile and light 

duty truck, metal furniture, magnet wire, and large appliances.* 

This report describes the types of coating operations found in this 

broad industri a1 category, identifies the sources and types of VOC emissions, 

and reports the available methods and costs for minimizing these emissions. 

Monitoring techniques for coatings which are low in organic solvents are 

suggested. More detai led discussions of coatings low in organic solvent 

and add-on control technologies are found in, "Control of Volatile Organic 

Emissionsfrom Existing Stationary Sources - Volume I: Control Methods for 

Surf ace Coating Operat ions, " EPA-45012-76-028, November, 1976. ASTM test 

methods for monitoring the organic sol vent content of coatings are summarized 

in, "Control of Volatile Organic Emissions from Existing Stationary Sources - Volume 11: Surface Coating of Cans, Coils, Paper, Fabrics, Automobi les and 

Light Duty Trucks," EPA-45012-77-008, May, 1977. 

*Earlier volumes in this series are available from the National Technical 

Information Service. 

iii 
OAQPS GUIDELINE SERIES 

The guidelines series of reports is being issued by the office of Air Quality Planning and Standards (OAQPS) to 

information to state and local air pollution control agencies; for example, to provide guidance on the acquisition 

and processing of air quality data and on the planning and analysis requisite for the maintence of air quality. 

Reports published in this series will be available - as supplies permit -from the Library Services Office (MD-35). 

U.S. Environmental Protection Agency, Research Triangle Park, North Carolina 2771 1; or, for a nominal fee, from 

the National 'Technical Information Service, 5285 Port Royal Road, Springfield, Virginia 221 61. 

Publication No. EPA-450/2-78-015 

(OAQPS NO. 1.2-101) 
The mi scell aneous metal part and product category includes hundreds 

of small to medium size industries for which writing individual guideline 

documents would be impractical . After reviewing these industries, EPA 

prepared this report to assist local agencies In determinq the level of VOC 

control that represents the presumptive norm that can be achieved through 

the application of reasonably avai 1able control technology (RACT) . Reasonably 

available control technology is defined as the lowest emission limit that a 

particular source is capable of meeting by the application of control 

technology that is reasonably avai 1 able considering technological and 

economic feasibility. It may require technology that has been applied to 

similar, but not necessarily identical source categories. It is not 

intended that extensive research and development be conducted before a 

given control technology can be applied to the source. This does not, 

however, preclude requiring a short-term evaluation program to permit 

the application of a given technology to a particular source. This latter 

effort is an appropriate technology forcing aspect of RACT. The diagram 

on the next page provides emission limits that represent RACT for the 

industries included in the miscellaneous metal parts and products category 

of the surface coating industry. 

It must be cautioned that the limits reported in the diagram are necessarily 

based on a general consideration of the capabilities and problems of the 

hundreds of industries which coat their products. It will not be applicable 

to every plant or even every industry within the many industries which 

coat. For example, the level of control which is herein recommended for 

a particular source may be based on a type of coating which cannot meet 

the specifications required of another product from a simi 1 ar source. 
Manufacture of Metal Parts and Products 

Air or forced air-dried items: 

Parts too larae or too heavy for Clear Coat 0.52 kg/liter practical size ovens and/or sensi - (4.3 1 bs/gal) tive heat requirements. Parts to 

which heat sensitive materials are 

attached. Equipment assembled 

prior to top coating for specific 

performance or qua1 i ty standards. 

No or infrequent color chanae 

or small number of colors 

appl i ed . 

owder Other Outdoor or harsh Frequent color chanae and/ 

oatings 0.36 kg/lite exposure or extreme or large number of colors 

.05 ka/l i ter (3.0 lbs/gal performance applied, or first coat on 

.4 lbs/gal) characteristics untreated ferrous substrat k 0.42 

(3.5 

kg/l 

lbs/gal) 

iter 

,

0.36 

(3.0 

kg/liter 

lbs/aal) 4

Logic diagram for derivation of emission 

limits for coatino of miscellaneous metal parts and 

products. 
The recomnended emission limits are based on the use of coatings 

low in organic solvents. They range from 0.05 to 0.52 Kg per liter 

(0.4 to 4.4 Ibs/gal). Equivalent reductions in VOC emissions can be achieved 

by the use of add-on control devices such as incinerators and carbon adsorbers. 

Many co'ating applicators, however, have expressed that they plan to meet 

future VOC regulations through the use of coatings low in organic solvents 

rather than resort to add-on control devices. 
GLOSSARY 

Single coat means only one film of coating is applied to the metal 

substrate. 

Prime coat means the first of two or more films of coatins applied 

in an operation. 

Topcoat means the final film or series of films of coating applied in 

a two-coat (or more) operation. 

Faraday caging means a repelling force generated in corners and small 

enclolsed areas of the metal substrate during electrostatic spraying of 

powders. 

Blocking agent means an organic agent which blocks or inhibits certain 

cross-linking or polymerization reactions. It is designed to separate 

from the monomer at some elevated temperature thereby allowins the 

reactions to proceed. 

Low organic solvent coating (LOSC) refers to coatings which contain 

less organic solvent than the conventional coatings used by the industry. 

Low organic solvent coatings include water-borne, higher solids, 

electrodeposition and powder coatings. 

Heat sensitive material means materials which cannot be exposed to 

temperatures greater than 800 to 950C (1800 to 2000F). 

Transfer efficiency means the portion of coating which is not lost or 

wasted during the application process expressed as percent. 
CONVERSION FACTORS FOR METRIC UNITS 


Metric Unit Metric Name 

Equivalent 

English Unit 

Kg 

3 kilogram (10grams) 2.2046 lb 

liter 1iter 0.0353 ft3 

dscm 

3 scmm (Nm ) 

Mg 

metric ton 

dry standard cubic meter 

standard cubic meter per min. 

6 

megagram (10grams) 

6 metric ton (10grams) 

35.31 dry std. ft. 3 

3 35.31 ft /min. 

2,204.6 lb 

2,204.6 lb 

Gj gigajoules ( 109joules) 9.486 x ~O~BTU 

In keeping with U.S. Environmental Protection Agency policy, metric units 


are used in this report. These units may be converted to common English units 


by using the above conversion factors. 


Temperature in degrees Celsius (cO) can be converted to temperature in 


degrees Fahrenheit (OF) by the fol lowing formula: 


tof = temperature in degrees Fahrenheit 

to = temperature in degrees Celsius or degrees Centigrade C 


Kg. per liter x 8.34 = lbs/gal 
TABLE OF CONTENTS 


PREFACE ............................... 


GLOSSARY ............................... 


CONVER.SION FACTORS FOR FIETRIC UNITS ................. 


1.0 SOURCES AND TYPES OF EMISSIONS ................. 
 1.1 General Discussion ..................... 
 1.2 Processes and Emission Points ............... 


2.0 APPLICABLE SYSTEMS OF EMISSION REDUCTION ............ 
 2.1 Water-Borne (Spray. Dip or Flow Coat) ........... 
 2.2 Water-Borne (Electrodeposition) .............. 
 2.3 Higher-Solids Coatings ................... 
 2.4 Powder Coatings ...................... 
 2.5 Carbon Adsorption ..................... 
 2.6 Incinerators........................ 
 2.7 References......................... 


3.0 COSTANALYSIS.......................... 
 3.1 Introduction........................ 
 3.1.1 Purpose....................... 
 3.1.2 Scope ....................... 
 3.1.3 Use of Model Plants ................. 
 3.1.4 Bases for Capital Cost Estimates .......... 
 3.1.5 Bases for Annualized Costs ............. 
 3.2 Solvent Emission Control in Metal Coating Operations .... 
 3.2.1 Model Plant Parameters ............... 
 3.2.2 Control Costs .................... 
 3.3 Cost Effectiveness .................... 
 3.4 Summary .......................... 
 3.5 References......................... 
 3.6 Bibliography........................ 


4.0 DETERMINATION OF APPLICABLE EMISSION LIMITATIONS ........ 
 References ........................... 

5.0 .ADVERSE AND BENEFICIAL EFFECTS OF APPLYING TECHNOLOGY ...... 5-1 


5.1 Water-Borne (Spray. Dip. or Flow Coat) ........... 5-1 


5.2 Water-Borne (El ectrodeposi tion) .............. 5-2 


5.3 Higher Solids Coatings ................... 5-4 


5.4 Powder Coatings ...................... 5-4 


5.5 Carbon Adsorption ..................... 5-6 


5.6 Incineration........................ 5-7 


5.7 References ......................... 5-11 


6.0 MONITORING TECHNIQUES AND ENFORCEMENT ASPECTS .......... 6-1 


APPENDIX A .SAMPLE CALCULATIONS OF CONTROL OPTIONS ;........ A-1 


APPENDIX A .Reference ........................ A-4 

1.0 SOURCES AND TYPES OF EMISSIONS 

This chapter provides general information on the mi scel 1aneous metal 


parts and products industries, the methods by which conventional coatings 


are applied, and the volatile organic compound (VOC) emissions which can be 


expected from the coatings. 


1.1 GENERAL DISCUSSION 


A wide variety of metal parts and products are coated for decorative or 


protective purposes. These are grouped into hundreds of small industri a1 


categories for which writing individual guideline documents would be 


unreasonable. This guideline document is intended to provide information on 


industries which coat metal parts and products, with the exception of the can, 


coil, magnet wire, automobiles and light duty truck, metal furniture and large appliance 


industries. These have been reported previously in "Control of Volatile Organic 


Emissions from Existing Stationary Sources - Volumes 11, 111, IV, and V." 

The 'industrial categories for which this guideline is intended and some 


examples of each category are listed in Table 1.1, 


There are far more dissimilarities than similarities between both the many 


plants and various industries represented by this category. For example, the 


geographic distribution of these industry categories is market-dependent and 


varies greatly. Some industries such as large farm machinery are located 


primarily in agricultural areas of the country such as EPA Regions V and 


VII. Others, like small appliances may be scattered throughout the country 

Table 1.1 LIST OF INDUSTRIAL CATEGORIES COVERED BY 

large farm machinery (harvesting, ferti 1 izing and planting machines, tractors, 

combines, etc.) 

small farm machinery (lawn and garden tractors, lawn mowers, rototillers, 

etc.) 

ma1 1 appliances (fans, mixers, blenders, crock pots, dehumidifiers, 

vacuum cleaners, etc. ) 

commerci a1 machi nery (computers and auxi 1 i ary equipment, typewriters, 

calculators, vending machines, etc. ) 

industri a1 machinery (pumps, compressors, conveyor components, fans, 

blowers, transformers, etc.) 

fabricated metal products (i .e., metal covered doors, frames). 

any other industrial category which coats metal parts or products under 

the Standard Industrial Classification Code of Major Group 33 (primary 

me.ta1 industries), Major Group 34 (fabricated metal products), Major 

Group 35 (non-electrical machinery), Major Group 36 (electrical machinery), 

Major Group 37 (transportation equi ment), Major Group.38 (miscel~aneous 

instruments), Major Group 39 (misce laneous e manufacturing ~ndustr~es), 

;.lajor Group 40 (railroad transportation) and Major Group 41 (transit 

passenger transportat ion). 

a Architectural and maintenance coatings are planned as the subject of a 

future guideline. 
although greater numbers of small appliance manufacturers may be located near 


large population centers. Within some industries, large variations in 


manufacturing techniques and procedures exist. Some facilities manufacture 


and coat metal parts, then assemble them to form a final product to be sold 


directly for retail. 0thers.often called "job shops", manufacture and coat 


products under contract; specifications differ from product to product. The 


metal parts are then shipped to the final product manufacturer to be assembled 


with othier parts into some product. Such facilities are often located in 


the vicinity of the manufacturers for whom they perform this service. 


The size of metal coating facilities and their mode of operation varies 


not only between industries but also within each industry. Two facilities 


coating the same product may apply different coatings using completely different 


application methods. The size of the facility is dependent on several things: 

number of coating lines, size of parts or products coated, type of coating 


operation (i .e., spray, dip, flow or roll coat), and number of coats of paint 


applied.. 


The coatings are a critical constituent of the metal coating industry. 


In many cases the coatings must provide esthetic appeal, but in all cases, 


they must protect the metal from the atmosphere in which it will be used. 


Adverse conditions may include moisture, sunlight, extreme temperature, 


abrasion and corrosive chemicals. A wide variety of coatings are applied 


by the many industries considered by this document. Both enamels (at about 


30-40 volume percent solids) and lacquers (at 10-20 volume percent solids) 


are used, although enamels are more common. Coatings are often shipped by 


the manufacturer as a concentrate but thinned prior to application. Typical 


coatings are a1 kyds, acrylics, epoxies, polyesters, vinyls, si 1icones, 

plastisols and phenols. 


Most coatings contain several (up to 10) different solvents. Typical 


solvents are ketones, esters, alcohols, a1 iphatics, ethers, aromatics and 


terpenes. 

1.2 PROCESSES AND EMISSION POINTS 


Each meta 1 coating line tends to be somewhat unique because of its age, 


product coated , design, and application technique. Figure 1.1 portrays 

common features found in many coating lines, and the following comments 


summarize these features. 


Flow diagrams a and b of Figure 1.1 show common methods of applying 

coatings on miscellaneous parts and products in both a conveyorized and 

batch, oven-baked single coat and two-coat operations. These methods typically 


include spray, dip, or flow coating for both single coats and primers. 


Spray is usually used for the topcoat. 


First the metal substrate is cleansed to remove grease, dust.,mill 


scale or corrosion. Often it is pretreated to improve adhesion. The most 


common method is the five stage cleansing process where the metal is cleaned 


with an aqueous caustic solution, rinsed with water, cleaned with a non- 


caustic solution, treated with phosphate and finally rinsed again with 


water. Chromate rinses or other pretreatments may also be used. Other 


cleaning methods are also used. The parts may be cleaned in a shot-blasting 

chamber by using organic solvent cleansers. (See Control of Volati le Organic 


Emissions from Solvent Metal Cleaning) The metal often passes through an 


oven to remove water before the coating is applied. 


Spraying is the more common method of applying coatings, for single coat 


operations, but flow coating and dipping are also used. For two coat operations, 


the primers are more likely to be applied either by flow or dip coating while 


the topcoats are almost always sprayed. 


To apply a flow coating, the metal parts are moved by a conveyor through 


an enclosed booth. Inside, a series of nozzles (which may be stationary or 


may oscillate), located at various angles to the conveyor, shoot out streams 


of coating which "flow" over the part. The excess coating drains into a 


sink located on the botton of the booth, is filtered and pumped back into a 


holding tank for reuse. Flow coating provides about a 90 percent transfer 


efficiency. Additional solvents are added to control the viscosity due to 


evaporation in the flow coater. 


The coated parts are often conveyed through a flashoff tunnel to 


evaporate solvent and allow the coating to flow out properly. The flow 


coater and flashoff tunnel are often located in a separate room in the facility 


and vented either through roof fans or by means of an exhaust system which 
 . 

maintains a slight negative pressure to capture the organic vapors. Exhaust 


gas flow is maintained at a rate sufficient to keep organic levels below 25 


percent of the lower explosive level or lower if necessary to protect the 


employees. 


One or two color single coat applications or primers for two coat 


applications may also be applied by dipping. The metal parts are briefly 


immersed either manually or by conveyor into a tank full of coating. The 


excess coating is allowed to drip from the part and drain back into the tanks. 


This method also provides about 90 percent transfer efficiency of the coating. 


The viscosity in dip coating, as on flow coating is very critical. The dip 


coating tank and drain board may be completely enclosed in a separate room 


and vented through roof fans, or through a ventilation system adjoining the 


tank and drain board. The flow rates from such a ventilation system will 

---- -- 

depend on the size of the dip tank. 


Spraying is the most common technique for applying single coat, some 


primer and most topcoat applications. It provides a transfer efficiency of 


40 to 70 percent. Electrostatic spraying with disc, bell and other types 


of spray equipment are commonly used to increase the transfer efficiency 


to 70 to 90 percent. Transfer efficiencies will vary with the part being 


coated and if manual, the expertise of the operator. "Touch-up" of assembled 


parts is usually performed manually. 


Spray coating is performed in a booth to contain overspray, to minimize 


contamination, and sometimes to control the atmosphere in which the coating 


is applied. The spray booths must be maintained at a slight negative pressure 


to capture overspray. Minimum acceptable air quality for spray booths are 


prescribed by OSHA. 


After coating and flashoff, the parts are baked in single or multi-pass 
 - --- -_ 

baking ovens at 150-230'~ (275-450'~). Since the cost of reducing organic 
 -- - --- -- -___ _ -- -- -

emissions in the exhaust stream are proportional to the volume of gas exhausted, 


it is important to minimize the infusion of air into the oven. Several factors, 


however, must be considered. An inlet air velocity of 15 to 45 mpm (50 to 


150 fpm) is required to prevent back convection and escape of emissions. 


Since the entry and exit openings are usually sized for the largest parts 


that may be baked on the line, this may result in greater oven exhaust rates 


than needed to meet 25 percent of the LEL. Dilution air and VOC levels have 


a strong effect on air pollution control costs. For example, halving the air 


flow doubles the organic concentration and reduces the capital and operating 


cost of add-on control equipment. Air curtains may be used at the openings 


to sweep the openings and minimize the air volume required to contain the 


emissions within the oven. 

-- - - 

Flow diagram c of Figure 1.1 shows a manual two-coat operation often 


used for items such as large industrial, construction, transportation equipment 


where the coatings are air or forced air dried. Ovens cannot be used because 

these assembled products include heat sensitive materials (i .e., tires, 


rubber tubing, plastic parts, etc.). Also, these products are often too 


large to be cured in an oven. Other air or forced air dried items include 


parts which are too thick or heavy to be cured in an oven and parts where 


production dictates that installation of ovens to cure coatings would not be 


economically feasible. For many of these items, the coatings must be resistant 


to steam cleaning, the outdoor elements as well as the corrosive coastal salt 


environment, and to the hazards of oil, gas01 ine, chemical spi 1 ls, fertilizer, 


moisture and other miscellaneous exposures. 


The assembled unit is cleaned to remove dirt, grease, or mill scale. 


The unit is usually moved to another room where it is spray coated with a 


primer, allowed to dry, spray coated with a topcoat and again allowed to air 


or farced air dry. These rooms which may be often as large as 8 x 8 x 18 

meters (25 x 25 x 60 feet). A draft fan prevents escape of overspray and 


maintains the concentration of organics within the worker safety limits 


prescribed by OSHA. Some of these items may even be coated outdoors. 


In summary, organic emissions from the coating of miscellaneous metal 


parts and products are emitted from the application and flashoff areas-aad 


the ovens (if used). For spray and flow coating, the bulk of the VOC is 


evaporated in the application and flashoff areas as noted in Table 1.2 


Figure 1.2 displays the relationship between VOC emissions and exhaust 


flow rate with isopleths of organic concentration in terms of the LEL. It 


emphasizes the effect of solvent concentration on the volume of exhaust gases 
that must be treated. Note that if a given coating line evaporates 140 


pounds of solvent per hour, the exhaust rate at one percent of the LEL 


(80,000 SCFM) is 10 times that of the same stream at 10 percent of the LEL 


(8,000SCFM). Since operating at higher LEL's clearly reduces the exhaust 

stream flow rate, the related capitol and operational costs of VOC emission 

control equipment are reduced. 


The flow rates and concentrations are influenced by several factors 

including the type of application system and the conditions within the 


flashoff area or oven which is the actual source of emissions. Unfortunately, 


flow rates are often designed for the most difficult combination of circum- 


stances. As a result, the rate may be excess of many items coated on a 


specific line and as a result, VOC levels are usually well below 25 percent of 


the LEL. 

Table 1.2 SOURCE OF VOC FMISSIONS FROM COATING MISCELLANEOUS 

METAL PARTS AND PRODUCTS 


PERCENT OF TOTAL VOC 


Application Method Application and Flashoff -Oven 


Dip 


Flow coat 


Spray (oven cured) 20-30 


Spray (air dried) not applicable 


a~his assumes a coating applied at 25 volume percent solids, 75 percent organic 


solvent which is equivalent to a VOC emission factor of 0.66 kg of organic

solvent emitted per liter of coating (5.5 lbs/gal) minus water. 

25% LEL 

0 


20 40 60 80 100 120 140 160 180 200 


Toluene emitted (lbs/hr) 


Figure 1-2. Data for toluene, LEL = 1.2% ("/ ), showing the 

re1 ationship between VOC emission, exhaust f18wrate and VOC 


concentration. 

2.0 APPLICABLE SYSTEMS OF EMISSION REDUCTION 

This chapter discusses coatings low in organic solvents (LOSC) and add-on 

equipment for the control of VOC from conventional coating applications 

used in the miscellaneous metal part and product industries. 

Table 2-1. SUMMARY OF APPLICABLE CONTROL TECHNOLOGY 

FOR MISCELLANEOUS METAL PARTS AND PRODUCTS 

Percent Reduction in 

Control Technology App.1 icat ion Organic Emissions 

Water-Borne (spray, dip Oven baked single coat, 60-90" 

or f 1 ow coat ) primer and topcoat; 

air dried primer and 

topcoat 

Water-Borne Oven baked single coat 90-95a 

(electrodeposi tion) and primer 

Higher-Sol ids (spray) Oven baked single coat, 50-8oa 

and topcoat; air dried 

primer and topcoat 

Powder (spray) Oven baked single coat 95-9ga 

and topcoat 

Carbon Adsorption Oven baked single coat, gob 

primer and topcoat 

application and flashoff areas; air dried 

primer and topcoat 

application and drying 

areas 

Incineration Ovens 

a~hese figures reflect only the range in reduction possible. The actual 

reduction to be achieved will depend on the composition of the coating 

and the replacement low organic solvent coating, transfer efficiency and 

the relative film thicknesses of the two coatings. 

b~his reduction in VOC emissions is only across the control device and 

does not take into account the capture efficiency. 
2.1 WATER-BORNE (SPRAY, DIP OR FLOW COAT) 


/ 

The application of water-borne coatings is similar to organic solventborne coatings thus conversion to water-borne coatings does not necessarily 

require extensive replacement of the existing coating application equipment. 

A reduction of 60 to 90 percent in organic emissions may be achieved by 

switching to water-borne coatings. The actual reduction, however, will 

depend on several variables: the composition of the original organic 

solvent-borne coating, the composition of the water-borne coating replacement, 

re1 ative transfer efficiencies, and the re1 ative f ilm thicknesses required. 

The transfer efficiency of water-borne coatings is similar to that of 

conventional coatings. A1 though water is the major carrier, some organic 

solvents must be included to temper the evaporation rate, provide the coating 

with the desired properties, and provide film coalescence. Some small 

appliance manufacturers have converted their electrostatic spray and dip 

coating 1 ines to apply water-bornes .' Water-borne coatings are now being 

applied on some farm machinery, on fabricated metal products and commercial 

machinery by flow coating, dipping, and both electrostatic and conventional 

spraying methods. 2 

Further technical details on the use of water-borne coatings may be 

found in Volume I, Sections 3.3.1 and 3.3.5.' 

2.2 WATER-BORNE (ELECTRODEPOSITION) 

Although converting to electrodeposited water-borne coatings wi 11 requi re 

new application equipment (i .e., tank, ultraf ilter, rinsing stations, etc.), 

it results in increased corrosion protection and can deposit thin coatings 

uniformly at greater transfer efficiency (about 99 percent) than any other 

application system. Electrodeposited coatings may be applied at 0.3 to 1.2 mils 

thickness, and film thickness may be adjusted by voltage and immersion time. 
Farm and commercial machinery, and fabricated metal product facilities have 


been reported to apply coatings by electrodeposition. 4
 ' One major advantage of water-borne coatings is that, unlike sol vent-borne 


coatings, the pretreatment dry-off oven may no longer be required. After an 


additional rinse with deionized water, the parts are subsequently grounded and 


immersed into the coating bath which may contain from 8 to 15 volume percent 


solids, 2 to 4 volume percent organic solvent, and the balance deionized water. 


An electrical potential causes the suspended solids to migrate and adhere to 


the part. (Coatings are available for application by either anodic or cathodic 


electrodeposition.) As the coated parts emerge from the bath, the coating is 


primarily solids with some water and trace quantities of organic solvent. These 


solvents control the flow of the coating during the curing process. The parts are 


then rinsed in several stages to remove any excess paint. (The rinse is then 


ultrafiltered to remove the water and organics. The paint solids are returned 


to the bath.) 


A complicating factor in determining the emission factor for electrodeposition 


is the very limited information now available on the final disposition of organic 


solvent. If the emission factor considers only the coating applied to the metal 


substrate (which would be emitted from the oven), it is only about 0.024 to 0.06 ka/liter 

(minus water). This factor does not consider any organic emissions which may occur 


from the tank or the rinsing stages. If the emission factor is based on the bath 


composition, it is much greater (i .e., .31 to -38 kg/liter minus water). This 


factor, however, does not consider the effect of solvent recycled to the bath 


or purged from the system. It appears that the methods by which ultrafilter 


residue is treated and how the coatings are replenished in the bath vary 


considerably from coater to coater. A conservative emission factor for 


electrodeposited coatings is 0.36 kg/liter less water. Certainly, however, with 

--- 

effect of improved transfer efficiency included, use of electrodeposi ted coatings 


can reduce VOC emissions by at least 90 to 95 percent over conventional coatings. 


El ectrodeposi ted coatings are normal ly baked at 150-200'~ (257-400'~) . 

Research is currently underway to eliminate the intermediate baking step now 


used to cure electrodeposi ted primers prior to topcoat application. 


Both the primer and topcoat would be baked as a one-coat system. This would 


provide attendant savings in capital and operating costs and fuel requirements. 


For further technical detai 1s on the use of electrodeposi tion coating 


technology, see Volume I, Section 3.3.1. 5 


2.3 HIlGHER-SOLIDS COATINGS 

The reduction in volatile organic emissions achievable by converting to 


coatings which contain higher solids ranges from 50 to 80 percent. Coatings with 


45 to 60 volume percent solids are currently being applied with spray or roll 

coating technology, Coatings with even greater solids content (60to 80 volume 


percent) are making inroads due to the development of new spray application 


technologies. Research is underway on higher solids coatings which will cure at 


ambient temperatures. These will be very attractive for applications such as 


large farm and industrial machinery. 


Higher-solids coatings can be applied by roll coating, or by spraying, either 


with automated electrostatic techniques, or manually. The first two are the 


more efficient application methods. Due to the higher viscosity of high-solids 


coatings, additional mechanical, thermal or electrical energy may be necessary 


for pumping and adequate atomization.6 Transfer efficiencies with high-solids 


coatings are often better than with conventional sol ids coatings particularly 


with electrostatic sprays. 7 

Further technical details on the use of high-solids coatings may be 


found in Volume I, Section 3.3.2. 8 
2.4 POWDER COATINGS 


Powder coatings have been sprayed as a single coat on small 


appl, iances, small farm machinery, fabricated metal product parts, and 


industrial machinery component parts.9 Powders can be applied by 


* 

electrostatic spraying at thicknesses from 0.9 to 5 mils, and thicknesses 


of much less than 1 mil have been achieved on experimental interior 


can lines. Powder coatings are also applied by dipping but the resultant 


film is much thicker, a minimum of about 6 mi 1s. After application 


of the coating, the metal part is moved to an oven where the powder 


par,ticles melt and flow to form a continuous, solid film. Powders 


are essentially 100 percent solids, but they can release about 0.5 - 3.5 weight percent of volatile organic compounds due to unblocking 


and cross1 inking reactions during the curing process. 10 


Powder coatings are applied by electrostatic spray with almost 


the same technique used for solvent-borne coatings , a1 though different 

equipment must be used. Film thickness can be controlled by the 


voltage potential. Powder coatings wrap around edges of complicated 


metal parts and are self-leveling on flat parts, but do not (as some 


of the 1 iquid counterparts also do not) coat small recesses we1 1. 


Depending on the application, this could be an advantage or disadvantage. 


This problem may be reduced or eliminated by preheating the parts, but 


may result in a thicker film. 


Powder coatings may be applied in smaller spray booths than 


the ones used for conventional coatings. As a result, the air require- 


ments necessary for proper ventilation may be greatly reduced. Use 


of powders may not only conserve space but may also reduce the energy 


&At least one firm has one year of production experience applying a 

coating thickness of 1 mil. Because thicker films are more common, 


the cost estimates in Chapter 3 are based on coating thicknesses of 


2 )mils. 

required to heat the spray booth make-up air during the winter months. 


Changing colors when applying powder coatings requires slightly 


more time than conventional coatings since any color contamination 


does not blend. If the operator tries to segregate the overspray color 


in order to recycle it, the booth and recovery unit should be cleaned 

thoroughly to avoid color contamination. This will require greater downtime. 


Two methods have evolved for minimizing the time required to 


change colors. Some facilities have several overspray recovery 


units available that may easily be attached to a single spray booth. 


Others have instal led several mobile spray booths and associated 


recovery equipment1' to minimize the number of changeovers that must 


be made. Still another approach has been to use the multicolored 


overspray on parts that do not have critical color specifications. 


A1 though curing temperatures, 170' to 230'~ (275-450'~) are often 


higher than with conventional coatings, powders do not require a 


flashoff zone, the air flow from the ovens may be reduced since no 


solvent is present. Further technical details on the application of 


powder coatings may be found in Volume I, Sections 3.3.3 and 3.3.5. 12 

2.5 CARBON ADSORPTION 


As discussed in Chapter 1, at least one-half of the volatile 


organic compounds from coating miscellaneous metal products is emitted 


from the application and flashoff areas. The remainder is emitted 


from the ovens. The use of carbon adsorption to collect the emissions 


from the application and flashoff areas can reduce those emissions by 


90 percent across the adsorber . 

Carbon adsorption is considered a viable control option for these 

areas although there are no known installations in facilities that coat 


mi scel 1 aneous metal parts or products. Carbon adsorption is technical ly 


feasible for these applications13 (no new inventions are required for 


its implementation), but pilot studies may be necessary before this 


control technology is instal led. 


The requisite size of a carbon adsorption unit is dependent on 


the exhaust flow rate, organic concentration, and the desorption 


period. Design parameters vary with each application because of the 


variety of metal parts coated and coatings used. About 95 percent 


effic,iency reportedly is effected by dry filters or by water or oil 


wash curtains14 Additional particulate removal may be necessary. 


however, if the remaining 5 percent is significant enough to render 


the bed inefficient. 


Flashoff areas have to be enclosed to maximize capture of the 


vola.tile organic emissions. The flow rates and VOC concentrations 


depend on the configuration of the coating line and the "tightness" 


of the enclosure. If the coating application areas are located on 


the first floor of the plant, for example, and the ovens are mounted 


on the roof, it may be difficult and expensive to try to contain the 


VOC that flashes off as the substrate traverses from the applicator 


to the oven. In other cases the application areas may be located 


near the oven where enclosing the flashoff areas would be less difficult. 


In some situations, the exhaust system on an oven will draw the solvent- 


laden air from the flashoff areas into the oven. 


Further technical details on the use of carbon adsorption may be 


found in Volume I, Section 3.2.1. 15 

-- 

2.6 INCINERATORS 


Incinerators are the most universally applicable control system 


for VOC. There are no serious technical problems associated with the 


use of either catalytic or noncatalytic incinerators on miscellaneous 


metal product coating facilities. Incinerator heat recovery efficiencies 


have improved and operating costs have been reduced significantly 


in recent years. 


Incineration systems may be more desirable ( less costly and 

perhaps more efficient) than adsorption for reducing VOC emissions 


from the baking ovens for several reasons: 


1. No cooling system is required. High temperature (150' to 


230'~) exhaust gases have to be cooled to 40°C or lower before 


entering a carbon bed. 


2. VOC in the exhaust stream can provide appreciable heat energy 

eg. 350'~ at 25 percent of the LEL. Thus at significant VOC levels, 


auxiliary fuel use can be minimized or sometimes even eliminated by 


the proper use of heat exchangers. 


3. Particulate and condensible matter from volatilization and/or 


degradation of resins, may coat the carbon bed. These materials will 


not affect an incinerator. 


It is desirable but not always feasible to incorporate secondary 


heat recovery systems to minimize fuel consumption and overall operating 


costs. Waste heat may be recovered for use in many process areas; for 


example, cleansing and pretreatment sections, the ovens, and for space 


heating during the colder months. 


Incineration of the exhaust from application and f lashoff areas 

is certainly technical 1y feasible, Its economic practicality may 

depend on minimizing the volume to be burned and recovering sufficient 


heat to keep fuel consumption at an acceptable level. 


Further technical details on the use of incineration may be found 

in Volume I, Section 3.2.2. 16 

2.7 REFERENCES 


1. Gallagher, V. N., Environmental Protection Agency, Research Triangle Park, 


North Carolina, Reports of trips to small appliance facilities in 1976. 


2. Springborn Laboratories, Inc. (formerly DeBell and Richardson, Inc.), Trip 


reports Nos. 18, 21, 69, 135, 142, 143, and 144. General Surface Coating 


Study under contract by EPA No. 68-02-2075. 


3. OAQPS Guidelines - "Control of Volatile Organic Emissions from Existing 

Stationary Sources - Volume I: Control Methods for Surface Coating 

Operations," EPA-450/2-76-028, November, 1976. 


4. Springborn Laboratories, Inc., Trip report No. 22, 87, 135. General 


Surface Coating Study under contract No. 68-02-2075. 


5. OAQPS Guidelines - Volume I, Op. Cit. 

6. DeYittorio, J. M., Ransburg Corporation, Application Equipment for High- 


Solids and Plural Component Coatings, Volume I, No. 2, April, 1976. 


7. LeBras, L. R., PPG Industries, Pittsburgh, Pennsylvania, Letter to 

V. Gallagher in comnent to draft of Volume 111, letter dated 

September 22, 1977. 


8. OAQPS Guidelines - Volume I, Op. Cit. 

9. Springborn Laboratories, Inc., Trip report No. 48, 88, 95, 98, 122, 123. 


Genera1 Surface Coating study under contract by EPA, No. 68-02-2075. 

10. Ccrle, Gordon E., Jr., Associationfor Finishing Processes of SME. 

Letter to Vera N. Gallagher in comment to the draft of this document, 


letter dated April 18, 1978. 


1 Springborn Laboratories, Op. Cit.,reference 9. 


12. OHQPS Guidelines - Volume I, Op. Cit. 

13. Johnson, W. J., General Motors Corporation, Warren, Michigan. Letter to 


Radian Corporation commenting on "Evaluation of a Carbon Adsorption - Incineration Control System for Auto Assembly Plants," EPA Contract No. 


68-02-1319, Task No, 46, January, 1976, dated March 12, 1976. 


14. Johnson, W. J., General Motors Corporation, Warren, Michigan. Letter to 


James McCarthy dated August 13, 1976. 


15. OAQPS Guidelines - Volume I, Op, Cit. 

16. Ibid. 

3.0 COST ANALYSIS 


3.1 INTRODUCTION 


3.1 .I Purpose 

The purpose of this chapter is to present capital and annualized 


costs for a1 ternative ways of control 1 ing solvent emissions at existing 


coating lines in the metal coating industry. A cost-effective analysis 


is included as an extension of the cost development. 


3.1.2 Scope 


Estimates of capital and annualized costs are presented for con- 


trol 1 ing volatile organic compounds (VOC) from application areas and 


curing ovens associated with conveyorized single-coat lines and con- 


veyorized two-coat lines. Control costs for manual two-coat lines are 


also estimated; in this process coated parts are air-dried, and only 


application area emissions require control. Flow, dip, and electro- 


static-spray coating are application techniques considered for the 


single-coat lines and for the prime coat in two-coat applications. 


Electrostatic-spray coating only is considered for the topcoat in two- 


coat lines. The following control alternatives are analyzed for the 


three-coat lines: 

-

A1 ternative I - Process Modification 

Emissions can be controlled by modifying coating equipment to 

ac.commodate one of the following low-solvent coating processes: 

1. Use of coating with a higher sol ids (60 percent or above) 

content 

2. Use of waterborne coatings 

3. Powder depos ition 

4. Electrodeposi tion (EDP) 

A1 ternative I1 - Exhaust Gas Treatment 

1. Carbon adsorption 

2. Thermal incineration (35% and 90% primary heat recovery) 

3. Catalytic incineration (35% primary heat recovery) 

Use of Model Plants 

Cost analyses are presented for three model sizes of existing 

coating 1 ines. Coating rates analyzed for conveyori zed si ngl e-coat and 

2 conveyorized two-coat operations are 139,000 m 2/yr, 743,000 m /yr, and 

2 1,486,000 rn /yr; the rates analyzed for manual two-coat operations 

2 2 2

are 418,000 m /yr, 604,000 m /yr, and 790,000 m /yr. The plant opera- ,-.-

ting time assumed for each type of application is 2880 hours/yr. 

It must be emphasized that model coating lines used in this analysis are very simple in that they involve a one-color, single-coat or 

two-coat application. Analyzing multicolor coating systems is beyond 

the scope of this analysis. Also, although control cost estimates based 

on the model plant approach may differ from actual costs incurred, they 
are nevertheless considered the best means of comparing relative costs 

and cost effectiveness of alternative control measures. 

3.1.4 Bases for Capital Cost Estimates 

Capital costs represent the investment required for retrofitting a 

control system, including costs of equipment, material, labor for installation, and other associated costs. Capital cost estimates are 

based on cost surveys of various installations presented in the references (1, 2). Most of the surveyed costs represent new installations. 

These costs have been modified to apply to retrofit installations. 

All capital costs are expressed in mid-1977 dollars. In addition 

to basic control equipment, capital costs include auxiliary equipment 

such as hoods, ducts, etc., as well as indirect expenses such as contingencies, contractor' s fee, and taxes. 

3.1.5 Bases for Annualized Costs 

Annualized costs represent the cost of operating and maintaining 

the control system and that of recovering the capital investment. 

Operating costs include costs for materials, utilities, and normal 

maintenance. Net annualized costs for process changes, i.e., line conversions, are incremental costs incurred in converting from high-solvent 

to 1 ow-sol vent coatings. The bases for these projected incremental 

costs are available in the referenced material (1, 2). Again, it must 

be emphasized that these analyses of model coating lines are provided as 

a means of comparing the relative costs of alternative control measures. 

Various coating industries have devoted considerable resources to the 

development of incremental costs of low-sol vent coating conversions. 
However, a comparison of these estimates may show a wide variation due 


to differences in some key assumptions. Specifically, coating material 


costs appear to have the greatest impact on annual costs. Differences 


in coating thickness requirements, transfer efficiencies, raw material 


costs, and coating specifications wi11 inf1uence these incremental 

costs. 


General cost factors used to estimate annualized costs for model 


coating lines are provided in Tab 1e 3-1. 


3.2. SOLVENT EMISSION CONTROL IN METAL COATING OPERATIONS 


3.2.1 Model Plant Parameters 


Table 3-2 presents technical parameters for the model sizes selec- 


ted. The estimated exhaust flow rates are based on solvent usage in 


the operation; and the estimated solvent coatings thickness and trans- 


fer efficiencies are based on typical practice. 


Add-on control systems can provide overall emi ssion control effi -

ciencies of the order of 80 to 90 percent. Separate control systems are 


assumed for appl ication/flash-off areas and drying ovens. Emission 


control efficiencies for process modifications range from 70 to 99 


percent (3, 4), depending on the type of coating selected. 


The cost analysis is based solely on model sizes. Generally no 


consideration has been given to detailed design characteristics of the 


model lines in terms of process equipment requirements, line speed, etc. 


However, it was necessary to consider gas flow rate, required dry coating 


thickness, and coating transfer efficiencies to estimate capital and 

Table 3-1. COST FACTORS USED IN COMPUTING ANNUALIZED COSTS 


-

I. Direct operating costs 

1. Materials (as purchased): 

- Conventional prime coating (40% sol ids)a 

- Alkyd conventional top coating (40% solids) 

- Solvent thinner 

- Polyester high sol ids coating (60% solid^)^ 

- Alkyd waterborne coating (40% solid^)^ 

- Epoxy powder coating 

- Electrodeposi tion waterborne (60% sol ids)a 

2. Utilities 

- Electricity 

- Natural gas 

- Steam 

3. Direct labor 

4. Maintenance labor 

- Process modifications 

- Add-on systems 

5. Maintenance Materials 

11. Annualized capital charges 

1. Depreciation and interest (process modification) 

- Depreciation and interest (add-on) 

2. Taxes, insurance, and administrative overhead 

a BY volume. 

$1.72/l iter (S6.501gal) 

$2.1111 iter ($8/gal) 

$0.28/liter ($1 .O7/gal) 

$3.17/1 iter ($12/ga1) 

$2.38/1 iter ($9/gal) 

$3.30/kg ($1.5011 b) 

$2.9l/l iter ($1 1 .O/gal ) 

$0.03/kw-hr 

$1.9O/GJ 

($2.00/mill ion Btu) 

$5.50/thousand 

($2.50/thousand 

$1 O/man-hr 

$1 O/man-hr 

0.02 x capital 

0.02 x capital 

Kg 

1b) 

cost 

cost 

0.1468 x capital cost 

0.1630 x capital cost 

0.04 x capital cost 
Tab1e 3-2. TECHNICAL PARAMETERS FOR MODEL COATING LINES 

Conveyorized single-coat and two-coat operation 

Line size, m2/yr (ft 2

/yr) 139,000 (1.500,000) 

Exhaust rate, Nm3

/sec (scfm) 

- Flow coat booth 

- Flow coat oven 

- Dip coat booth 

- Dip coat oven 

- Spray coat booth 

- Spray coat oven 

Manual two-coat operation 

2 2 Line size, m Iyr (ft lyr) 

3 Exhaust rate, Nm Isec (scfm) 

- Prime coat booth 28.55 (60,500) 

- Top coat booth 28.55 (60,500) 

Process conversion data 

Dry coating thickness, wn (mils)/coat Transfer efficiency, %a 

- Conventional sol vent 25 (1) 8ob 

- High solids solvents 30 (1.2) 80 

- Powder deposition 50 (2) 9 5 

- EDP 18 (0.7) 9 5 

- Waterborne solvents 25 (1) 80 -gob 

a Reference 3. 

80 percent far spray coating, 90 percent for dip and flow coatings. 
operating costs of the control a1 ternatives considered. Therefore, any 


changes in these parameters (gas flow rate, dry coating thickness, coat- 


i ng transfer efficiency) will produce considerable impact on control 


costs and cost-effectiveness of different options. 


3.2.2 Control Costs 


Table 3-3 through 3-9 present details of control cost estimates 


for seven coating operations. Tables 3-3, 3-4, and 3-5 present control 


costs for the conveyorized single-coat operation; Tables 3-6, 3-7, and 


3-8 for the two-coat conveyorized operation; and Table 3-9 for the 


manual two-coat operat ion. 


Capital costs of converting 1 ines to higher-sol ids coatings or to 


waterborne coatings are those re1 ated to appl i cation equipment modif i-


cations only. Suppliers indicate that conversion to high-solids (60 


percent or more sol ids content) coatings, particularly a high speed 


turbine be1 1 or disc high-sol ids coating, requires instal lation of new 


pumps and fluid transfer equipment. The cost estimates include this 


equipment (5). Capital cost estimates change radical ly for waterborne 


coating operations if paint sources are not located close to application 


equipment and if stainless steel piping is used for paint recirculation 


systems (6). 


Capital costs of converting to a powder coating are associated with 


installation of powder application and recovery systems. Because model 


lines are one-color systems, only one recovery system is included in 


capital cost estimates. Some energy, waste disposal , and direct 1 abor 
0 

. u c a w - 

> u 

O 5 

F c. 

'2 

u w L 

C . m 0 C 

al al h W * 

L O W 

w x > 0) u 0 U.- C .- al 2,- LLC D m u U 

mv- al C'C s .u '- 

hS m Lo- O * 

22.5 

nu 4 w L u- 0 4 

t U w 1 u 

u 3 m 

L 0 Y a-s 

PC L 

m c > moo 

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.r w n 3 > m 0 - C U 

2 z 2 0 1 m r L m 

wal* 

C x u .r * 

z 2z '- 2 L v - 0 c Ln m n m 7 
- 

-- 

-- 

Table 3-4. INCREMENTAL COSTS OF SOLVENT EMISSION CONTROL OPTIONS FOR CONVEYORIZED SINGLE-COAT OPERATION, 

DIP-COAT APPLICATION 

(Mid-1977 thousand dollars) 

Appl icable control option 

Cost itern 

Waterborne 

ned iu -

-

sma 1 -

)sting!

Lea 

-

large

Electrodeposition (EOP) 

KElx 

ned

-

iurn :- A 

small large 

rdsorption and 

incineration 

C primary heat 

:overyb 

Carbo~ 

they 

with . 

I 

Sf 

Small 

a 

mediun -

large 

Carbon adsorption and 

catalytic incineration 

with 35% primary heat 

recovr cryb

mediurn 

Ize 

large 

Thermal incineration 

with 90% primary heat 

recover# 

ze 

large -

urce

red

-

iur -

sma 1 - - - " Capital investment 12 20 28 65 178 64 126 

" Annual costs (credits)d 

Material 2 11 22 (9) (46) 0 0 

Electricity 0 0 1 2 9 0 1 

Fuel 0 (2) (3) 0 (1) 5 10 

Maintenance 1 1 1 3 8 3 6 

Capital charges 2 4 5 12 33 13 25 

' Total annualized cost (credit] 5 14 26 8 3 21 42 

O Solvent emissions control led. 

WYr 

6 35 69 7 39 7 39 

O Emission reduction. X 80 80 80 90 90 90 90 

Cost effectiveness (credit) , $/Mg of solvent control led 833 400 377

- 1143 -

77 DO0 -

077

a See Table 3-2 for source sizes. 

Carbon adsorption on dip-coat booth and incineration with 35 percent primary heat recovery on drying oven. 

Thermal incineration with 90 percent primary heat recovery on dip-coat booth and drying oven. * Incrmnts of waste disposal costs, labor costs, and labor overhead are insignificant; these are not included in the annual costs. 
- - 

Table 3-5. INCREMENTAL COSTS OF SOLVENT EMISSION CONTROL OPTIONS FOR CONVEYORIZED SINGLE-COAT OPERATION, 

SPRAY-COAT APPLICATION 

(Mid-1977 thousand do1 lars) 

Applicable control 0~tion 

1 


arbon adsorptton and rbon adsorption and 

hem1 incineration talytic tncineration henna1 incineration 

4th 352 prt "%ry heat th 352 pri "gry heat ti th 902 pri -y heat 

recovery recovery recover aterborne GIoat:Inga High sol ids coatings Powder deposition 

rce s L 

lrge 

-

I source 

iGaiiim

size 

lrge 

-sMll 

sou 

Kii 

e siz 

arge 5 

OUI L

r rge Cost itern -

ediunr lrge 7 --- - - Capital Investment 20 )71 369 648 957 113 

C O Annual costs (credits) 

0 0 0 0 0 

Material 9 

Electricity 0 17 2 9 17 12 

12 2 4 6 130

W Fuel (2) I 44 16 31 43 77 

ehintenance 0 


Capital charges 4 195 72 136 190 343 

O Total annualized dost 12 268 92 180 256 562 

-I 1 

" Solvent 

(credit)

emissions conlii

trolled, Mglyr 4 1 8 1 8 41 81 88 

80 ! " Emission reduction, % 79 79 79 79 85 

" Cost effectiveness 

(credit), S/Mg of 

solvent controlled 293 4390 3161 

- 6 386 

- a see Table 3-2 for source sizes. 

Carbon adsorption on spray-coat booth and incineration with 35 percent primary heat recovery on drying oven. 

Thermal incineration with 90 percent primary heat recovery on spray-coat booth and drying oven. 

Increments of waste disposal costs. labor costs, and labor overhead are insignificant; these are not included in the annual costs. 
Tabie 3-6. INCREMENTAL COSTS OF SOLVENT EMISSION CONTROL OPTIONS FOR EONVEYORIZED TWO-COAT OPERATION, 

FLOW- AND SPRAY-COAT APPLICATION 


(Mid-1977 thousand do1 lars) 

Applicable control option 


.arbon adsorption and 


Cost item 

1 Waterborne coz L kt ings

large -

Powder depos 

M medium -

sma 1 

ion 

e 

arge 

thermal incineration 

with 351 pri I

7-y heat 

-

arge

recover) 

-Sf

small 

:atalytic incineration 

rith 35% pri~ ry heat recoverv"g d 

edi um - arge 

SOL 

-

small

Thermal incineratton 

with 90% primary heat 

recover6 

a Capital Investment 56 1299 539 903 1259 

O Annual costs (credits) 

Material 86 0 0 0 0 

Electricity 1 19 3 10 19 

Fuel (6) 20 4 6 8 

Mi ntenance 3 58 25 42 57 

Capital charges 10 260 108 187 252 

* Total annualized cost (credit 94 357 140 245 336 

O Solvent emissions control led. 

WYr 152 155 15 78 155 

Emission reduction, 1 80 82 82 82 82 

" Cost effectiveness (credit). 

$/Mg of solvent controlled -

618 2303 9333 3141 2167 I 

a See Table 3-2 for source sizes. 

Carbon adsorption on coating booth and incineration with 35 percent primry heat recovery on drying oven. 


Thermal incineration with 90 percent primary heat recovery on coating booth and drying oven. 


Increments of waste disposal costs, labor costs, and labor overhead are insignificant; these are not included in the annual costs. 

Tab1e 3-7. INCREMENTAL COSTS OF SOLVENT EMISSION CONTROL OPTIONS FOR CONVEYORIZED TWO-COAT OPERATION, 


DIP- AND SPRAY-COAT APPLICATION 


. (Mid-1977 thousand do1 1ars ) 

Applicable control optfon --

Carbon adsorption and Carbon adsorption and 

-

<

Powdc 

-I

deposition 

~i ze 4 

them1 incineration 

with 35% primary heat 

recoveryb source size 

catalytic Incineratlon 

with 35% pri9ry heat 

recovery 

Thermal incineration 

with 90% primary heat 

recove@ 

source size 

Cost item -small large 1 small rediumllarge edium - arae I smalllmediumllarae smalllmedium Ilarcre 

O Capital investment 24 994 

Annual costs (credits? 

Material 8 0 

Electricity 0 10 

Fuel (11 18 

Maintenance 1 45 

Capital charges 4 199 

O Total annualized cost (credit 12 272 

Solvent emissions control led, 

M9lyr 14 78 

O Emission reduction, X 80 82 

O Cost effectiveness (credit), 

$/Mg of solvent controlled 857

- 3487 

a See Table 3-2 for source sizes. 

Carbon adsorption on coating booth and incineration with 35 percent primary heat recovery on drying oven. 

Thermal incineration with 90 percent primary heat recovery on coating booth and drying oven. 

Increments of waste disposal costs, labor costs, and labor overhead are insignificant; these are not included in the annual costs. 
Tab1e 3-8. COSTS OF SOLVENT EMISSION CONTROL OPTIONS FOR CONVEYORIZED TWO-COAT OPERATION, 

SPRAY-COAT APPLICATION 

(Mid-1977 thousand do1 lars) 

A991 icable control option 

Waterborne ( 

-

ltings

lea Htgh solids solvent! 

-

Powder 

deposition pr 

:arbon adsorption ant 

:henna1 incineration 

rith 35% prifnpry heal 

recoveryb 

source size 

Carbon adsorption and 

catalytic in cine ratio^ 

4th 35% primary heat 

recoveryb 

2 

Thermal incineration 

with 90% primary heat 

recoveryC 

-

source size 

Cost item sma 1 ned i un large - small -

nedi un small medium large -

small -

arge smal

-1

O Capital investment 56 86 761 1397 1943 720 1902 439 

" Annual costs(credi ts)' 

Material 86 56 0 0 0 

Electricity 1 0 4 34 3 

Fuel (6) (3) 4 12 32 

w 

I Maintenance 3 4 33 86 20 

w Capital charges 10 16 144 380 88 

O Total annualized cost 94 73 185 512 143 

" 

(credit) 

Solvent emissions controlled. Mg/yr 165 7 2 15 163 16 

" Emission reduction. % 80 70 79 79 85 

" Cost effectiveness 

(credit), $/Mg of 

solvent control led -

570 014 

-

12233 3140 8938 

a See Table 3-2 for source sizes. 

Carbon adsorption on spray-coat booth and incineration with 35 percent primary heat recovery on drying oven. 

Thermal incineration with 90 percent primary heat recovery on spray-coat booth and drying oven. 

Increments of waste disposal costs, labor costs, and labor overhead are insignificant; these are not included in the annual costs. 
Table 3-9. COSTS OF SOLVENT EMISSION CONTROL OPTIONS FOR MANUAi TWO-COAT OPERATION 

(Mid-1 977 thousand do1 lars) 

Applicable control option 

IThennal incineration 

Waterborne ( 

5 E L

)stings 

r e 

Carbon adsorption 

source size 

with 90% primary heat 

recovery source S I ~ 

Cost item -

small iediun lediun -

arge small lmedium)large I 1 

smalllmedium 1 arge - " Capital investment 34 86 2758 

Annual costs (credits)b 

Material 24 91 0 

Electricity 0 0 10 

Fuel (21 (3) 110 

Maintenance 2 4 124 

Capntal charges 6 16 276 

" Total annualized cost (credit) 30 108 458 

O Solvent emissions controlled. 

Mglyr 12 20 25 

" Emission reduction, 1 80 70 85 

" Cost effectiveness (credit), 

$/Mg of solvent controlled 2500 

- 5400 8320 

-

a See Table3-2 for source sizes. 

Increments of waste disposal costs, labor costs, and labor overheads are insignificant; these are not included in the annual 

costs. 
savings are estimated for powder coating conversions (1, 2); however, a 


higher coating thickness of 50 urn (2 mils) assumed for powder coating 

diminishes possible savings. 


For electrodeposi tion, lower applied film thickness helps override 


some of the associated increased electrical costs (1). 


Annualized costs of incineration of oven emissions primarily 


represent fuel required to raise the temperature of the exhaust gases 


from 160°C (320°F) to 760°C (1400°F). 


3.3 COST EFFECTIVENESS 


Figures 3-1 through 3-7 present cost-effectiveness curves for the 


options analyzed: Figures 3-1, 3-2, and 3-3 for conveyorized single- 


coat operation; Figures 3-4, 3-5, and 3-6 for conveyorized two-coat 


operation; and Figure 3-7 for manual two-coat operation. These curves 


represent the effect of line size on the cost per unit weight of solvent 


controlled. The cost per unit weight of solvent controlled decreases 


with the increasing line size in a11 cases. 


The two most cost-effective options eval uated for conveyori zed 


single f low-coat and single dip-coat operations appear to be convers ion 


to waterborne coatings and conversion to the electrodeposition process. 


The most costly options appear to be add-on control devices. Conversion 


to waterborne coatings seems to be a cost-effective option for spray 


coating in a conveyorized single-coat operation; carbon adsorption 


combined with thermal i ncineration, with 35 percent primary heat recovery 


is the most costly. 

0 WATERBORNE COATINGS 

o ELECTRODEPOSITION (EDP) 

CARBON ADSORPTION AND THERMAL INCINERATION 

WITH 30% PRIMARY HEAT RECOVERY 

A CARBON ADSORPTION AND CATALYTIC INCINERATION 

WITH 30% PRIMARY HEAT RECOVERY 

V THERMAL INCINERATION WITH 90% 

PRIMARY HEAT RECOVERY 

I i 

0 5 10 15 

COATING RATE, 5 2 10 m /year 

FIGURE 3-1. Cost-Effectiveness Comparison of Solvent 

Emission Control Options 

Conveyorized Single-Coat Operation 

Flow-Coat Appl ication 
WATERBORNE COATINGS 

0 ELECTRODEPOSITION (EDP) 

n CARBON ADSORPTION AND THERMAL INCINERATION 

WITH 30% PRIMARY HEAT RECOVERY 

A CARBON ADSORPTION AND CATALYTIC INCINERATION 

WITH 30% PRIMARY HEAT RECOVERY 

V THERMAL INCINERATION WITH 90% 

PRIMARY HEAT RECOVERY 

I 1 

5 10 

5 2 COATING RATE, 10 m /year 

FIGURE 3-2. Cost-Effectiveness Comparison of Solvent 

Emission Control Options 

Conveyorized Single-Coat Operation 

Dip-Coat Appl ication 
WATERBORNE COATINGS 

CARBON ADSORPTION AND THERMAL INCINERATION 

WITH 30% PRIMARY HEAT RECOVERY 

A CARBON ADSORPTION AND CATALYTIC INCINERATION 

WITH 30% PRIMARY HEAT RECOVERY 

V THERMAL INCINERATION WITH 90% 

PRIMARY HEAT RECOVERY 

v POWDER DEPOSITION 

HIGH SOLIDS COATINGS 

1 I 

5 2 COATING RATE, 10 m /year 

FIGURE 3-3. Cost-Effectiveness Comparison of Solvent 

Emission Control Options 

Conveyorized Single-Coat Operation 

Spray-Coat Application 
WATERBORNE COATINGS 

n CARBON ADSORPTION AND THERMAL INCINERATION 

WITH 30% PRIMARY HEAT RECOVERY 

r CARBON ADSORPTION AND CATALYTIC INCINERATION 

WITH 30% PRIMARY HEAT RECOVERY 

V THERMAL INCINERATION WITH 90% 

PRIMARY HEAT RECOVERY 

V POWDER DEPOSITION 

1 I 1 

5 10 15 

5 2 COATING RATE, 10 m /year 

FIGURE 3-4. Cost-Effectiveness Comparis.on of Solvent 

Emission Control Options 

Conveyori zed Two-Coat Operation 

Flow- and Spray-Coat Appl ication 
WATERBORNE COATINGS 

6 CARBON ADSORPTION AND THERMAL INCINERATION 

WITH 30% PRIMARY HEAT RECOVERY 

A CARBON ADSORPTION AND CATALYTIC INCINERATION 

WITH 30% PRIMARY HEAT RECOVERY 

V THERMAL INCINERATION WITH 90% 

PRIMARY HEAT RECOVERY 

V POWDER DEPOSITION 

1 I 

5 2 COATING RATE, 10 m /year 

FIGURE 3-5. Cos t-Effectiveness Comparison of Sol vent 

Emission Control Options 

Conveyorized Two-Coat Operation 

Dip- and Spray-Coat Application 
FIGURE 3-6. Cost-Effectiveness Comparison of Solvent 

Emission Control Options 

WATERBORNE COATINGS 

A CARBON ADSORPTION AND THERMAL INCINERATION 

WITH 30% PRIMARY HEAT RECOVERY 

4 CARBON ADSORPTION AND CATALYTIC INCINERATION 

WITH 30% PRIMARY HEAT RECOVERY 

V THERMAL INCINERATION WITH 90% 

PRIMARY HEAT RECOVERY 

V POWDER DEPOSITION 

HIGH SOLIDS COATINGS 

Conveyorized Two-Coat Operation 

Spray-Coat Application 

15,000 - 

12,000 

0 

W 

A 

A 

0 

9000 

Z 

0 

U 

IZ 

W 

> 

6000 5? 

LL 

0 

pr 

3000 

5 

0 

0 

0 

(3000) 

I I I 

- 

- 4 

- - 

- - 

--Q - 

u CI 

V 

- 

, I I I 

0 5 10 15 

5 2 COATING RATE, 10 m l year 
WATERBORNE COATINGS 


ACARBON ADSORPTION AND THERMAL INCINERATION 


WITH 30% PRIMARY HEAT RECOVERY 


V THERMAL INCINERATION WITH 90% 

PRIMARY HEAT RECOVERY 


- HIGH SOLIDS COATINGS 

I I 

I -

t7,


0 


0 


4000 -

r 

I I 0 -

0 5 10 


COATING RATE, 10 5 rn2/year 

FIGURE 3-7. Cost-Effectiveness Comparison of Solvent 


Emission Control Options 


Manual Two-Coat Operation 

Conversion to a powder-coating process is the most cost-effective control option evaluated for conveyorized two-coat operations. 

Add-on control systems appear to be considerably more expensive than 

process modification options. 

Conversion to waterborne coatings is the least costly option 

evaluated for manual two-coat operations. Again, add-on control systems 

cost much more than process changes. 

In flow and dip coating in conveyorized single-coat operations, 

thermal incineration with 90 percent primary heat recovery* appears to 

be a more cost-effective add-on control than carbon adsorption with 

either thermal or catalytic incineration+ with 30 percent primary heat 

recovery. This system also appears to be the most cost-effective for 

small size lines only in all other operat ions (spray-coating in conveyorized single-coat operations and all coatings in conveyorized twocoat operations); however, it is the least cost-effective for medium 

size and large size lines. For these applications, carbon adsorption 

with thermal incineration at 30 percent primary heat recovery seems to 

be more cost-effective than carbon adsorption w ith catalytic inc ineration at 30 percent primary heat recovery. 

The carbon adsorption system appears to be more cost-effect ive than 

thermal incineration, with 90 percent primary heat recovery on manual 

two-coat operations. 

* Thlermal incineration with 90 percent primary heat recovery is applied 

on coating booth and drying oven. 

+ Ca~rbon adsorption on booth and thermal/catalytic incineration on drying 

oven. 
3.4 SUMMARY 

Cost analyses of the model lines indicate that modification of the 

coating process to a low-solvent coating usually appears to be more 

cost--effective for control of VOC than add-on control. However, because 

annualized costs for a1 ternative coating systems are greatly affected by 

assumptions implicit in the calculation of coating costs, comparisons 

between alternative coating systems can exhibit significant case by case 

variations. 
3.5 REFERENCES 

1 Second Interim Report on Air Pollution Control Engineering and Cost 

Study of the General Surface Coating Industry. Prepared by Springborn Laboratories, Inc., under EPA Contract No. 68-02-2075. August 

23, '1977. 

2. Second Interim Report on Air Pollution Control Engineering and Cost 

Stud,y of the General Surface Coating Industry - Appendixes A & B. 

Prepared by Springborn Laboratories, Inc., under EPA Contract No. 

68-02-2075. August 23, 1977. 

3. Study of Systems for Heat Recovery from Afterburners. Industrial 

Gas Cleaning Institute, Stamford, Connecticut. EPA Contract No. 

68-02-1473, Task No. 23. October 1977. 

4. REECo Newsletters 1 through 4. REECo Regenerative Environmental 

Equipment Co., Inc., Muncy, Pennsyl vania . 1973. 

5. Information supplied to U .S. EPA by Regenera ti ve Environmental 

Equipment Co., Inc. (REECo), March 31, 1978. 

6. High Solids Coatings Volume 2, No. 2. Technology Marketing Corporation, Stamford, Connecticut. April 1977. 

3.6 BIBLIOGRAPHY 

Control of Volatile Organic Emissions from Existing Stationary 

Sources, Volume I: Control Methods for Surface-Coating Operations. 

EPA-450/2-76-028, Research Triangle Park, North Carolina. November 

1976 (OAQPS NO. 1.2-067). 

Control of Volatile Organic Emissions from Existing Stationary 

Sources, Volume 11: Surface Coating of Cans, Coils, Paper, Fabrics, Automobiles, and Light-Duty Trucks. EPA-450/2-77-008, 

Research Triangle Park, North Carolina. May 1977 (OAQPS No. 1.2-073). 

Report of Fuel Requirements, Capital Cost and Operating Expense for 

Catalytic and Thermal Afterburners. CE Air Preheater, Industrial 

Gas Cleaning Institute, Stamford, Connecticut. EPA-450/3-76-031. 

September 1 976. 

Ca,pital and Operating Costs of Selected Air Pollution Control 

Systems. GARD, Inc., Niles, Illinois. EPA Contract No. 68-02-

2072. May 1976. 
4.0 DETERMINATION OF APPLICABLE EMISSION LIMITATIONS 

This chapter shows how an agency may use the logic diagram presented 

as Figure 4.1 to develop a standard appropriate for almost any coating 

process which applies surface coatings on a metal substrate. 

The procedure for determining emission limits which represent 

the presumptive norm achievable by various processes. It requires some 

knowledge of the industry, the coating process and the requirements 

demanded of the coating. The procedure is to start at the top of 

Figure 4.1 and at each decision node (Indicated by a circle) choose 

the appropriate option. Unti 1 reaching a block that presents the 

level of control that is presumed to be ach 

of RACT by the manufacturer. 

As an examp le, to find the recommended 

ievable through the applicat ion 

emission limit for a 

continuous operation that coats phosphate treated machine brackets with 

a black oven cured dipcoat at 0.7 mils film thickness, the procedure 

is as follows: 

Beginning at the top, proceed to node B. 

The item is not clear-coated, does not contain any heat sensitive 

materials and is baked in an oven when coated, so proceed to node C. 

' The brackets are marketed in one color, so proceed to node D. 

Because powder coatings are not applicable in this case, the 

recommended emission limit for this process is 0.36 kg/liter 

(3.0 lbs/gal) minus water. 

This would then be the level of control presumed to represent RACT 

for this process. It may be achieved through the use of either waterborne dip or electrodeposited water-borne coatings. Higher solids and 

powder coatings can also be used but may result in thicker films than 
the 0.7 mil obtained from low solids coatings. 


Current technology does not provide low-pol luting coatings which 


can successfully replace conventional coatings for a1 1 the speci a1 ty 


items coated by the many industrial categories covered by these 


emission limits. Some low-polluting coatings are beinq used on production 


lines while others are in various stages of research. There wi 11 be, 


however, si tutations where low-pol luting coatings may never be applicable 


and even the use of add-on control technology may not be feasible 


ei tlher technical ly or economically. 

P Manufacture of Metal Parts and Products 


Auto 


and 


coil ('I ire(^) Other Light Metal (2) Large(4) 

Cuty Furniture Appliance


~ruck(l) 


I 


Air or forced air-dried items: 


Parts too large or too heavy for 


practical size ovens and/or sensi- 


tive heat requirements. Parts to 


which heat sensitive materials are 


attached. Equipment assembled 


prior to top coating for s~ecific 


performance or quality stand r s. 


0.42 kglliter (3.5 lbslgal) 757 1 

No or infrequent color chanoe, 


or small number of colors 


applied. 


I Outdoor or harsh Frequent color chanqe and/ 


exposure or extreme or large number of colors 
 I

performance applied, or first coat on 
 characteristics 


0.42 kg/liter (5) , untreated ferrous substrat 

0.36 kglliter
 (3.5 lbs/gal) I I (3.0 lbslsal) (7) 

Fiqure 4.1 Logic diagram for derivation of emission 


limits for coatina of miscellaneous metal parts and 


products. 

4.1 REFERENCES 


The recommended emission limitations for this category are given in 


"Control of Volatile Organic Emissions from Existing Stationary 


Sources - Volume 11: Surface Coating of Cans, Coils, Paper, Fabric, 

Automobiles and Light Duty Trucks ," EPA-450/2-77-008, May, 1977. 

The recommended emission limitations for this category are given in 


"Control of Volatile Organic Emissions from Existing Stationary Sources - Volume I I I Surf ace Coating of Metal Furniture," EPA-450/2-77-032, 


December, 1977. 


The recomnended emission limitations for this category are given in 


"Control of Volatile Organic Emissions from Existing Stationary 


Sources - Volume IV: Surface Coating for Insulation of Magnet 

Wire," EPA-450/2-77-033, December, 1977. 


The recommended emission limitations for this category are given in 


"Control of Volatile Organic Emissions from Existing Stationary 


Sources - Volume V: Surface Coating of Large Appliances," EPA-450/ 

2-77-034, December, 1977. 


This emission limit is achievable by use of about 52 volume percent solids 


organic solvent-borne coating. Units for this and other limitations 


are kilograms of solvent emitted per 1 iter of coating applied (minus 

water) , 

This limit is achievable by use of a 41 volume percent solids organic 


solvent-borne or a water-borne equivalent coating. 


This emission limit is acheivable by use of a 59 volume percent higher 


solids or a water-borne equivalent coating, or powder or electrodeposited 


water-borne coatings. DuPont Comments to the First Draft of Control of 


Volatile Organic Emissions from Existing Stationary Sources - Volume VI: 

Surface Coating of Miscellaneous Metal Parts and Products, Letter Dated 


April 20, 1978. 


There are some products for which a coating thickness greater than 2 mi 1s 


is required hut ather coating quality or performance requirements preclude 


the use of powder coatings. Comments from Deere and Company on the First 


Draft of Control of Volatile Organic Emissions from Existing Stationary 


Sources - Volume VI: Surface Coating of Miscellaneous Metal Parts and 

Products, Letter dated March 29, 1978. 

5.0 ADVERSE AND BENEFICIAL EFFECTS OF APPLYING TECHNOLOGY 

This chapter reviews the adverse and beneficial effects of each technique 

which reduces VOC emissions. This includes not only environmental aspects but 

also energy and cost. It also highlights any limitations of low organic 

sol vent techno1 ogy as compared to conventional high organic sol vent coatings . 

5.1 WATER-BORNE (SPRAY, DIP, OR FLOW COAT) 

There are several advantages to converting to water-borne coatings. 

" Conversion to water-borne coatings will likely be the first option 

considered by many facilities because of the possibility that these 

coatings can be applied with minimal modification of existing equipment. 

" Converting to water-borne coatings provides a potential decrease 

in toxicity and flammability. 

" Water-borne coatings may be thinned with water. 

" Coating equipment can be cleaned or flushed with water rather 

than organic solvent. (If water-borne coatings are allowed to dry, however, 

they are then no longer soluble in water and must be cleaned with solvent. 

" Use of water-borne coatings may allow a decrease in oven temperature. 

" Use of water-borne coatings will permit some reduction in air flow 

since the amount of organics which must be evaporated in the oven is 

1 reduced. (The permissible reduction may be 1 imi ted, however, by high humidity 

within the oven which will result in condensation on the oven walls and possibly 

cause improper curing of the film. 

In some cases the dry-off oven may no longer be necessary. 2 

There are some potential disadvantages to water-borne coatings when compared 

with conventional organic-borne coatings. 
Spraying with water-borne coatings may require closer attention 

to detail than with organic-borne coatings because temperature, humidity, 

gun-to-metal-part distance, and flashoff time may affect the appearance 

and performance of the coating. 

On many large electrostatic spray lines, use of water-borne coatings 

may be impractical because of the difficulties involved in electrically 

insulating the entire system. 

Water-borne coatings applied by dip and flow coating application 

equipment will need to be monitored more closely due to their more sensitive 

chemistry. 

An additional rinse may be needed. Cleansing and pretreatment of the 

substrate are more critical because of possible coating contamination and pH 

changes within the dip or flow coating tank. 3 

Some equipment may have to be replaced or adjusted (due to different 

surface tension of water than that of organic solvent) or protected from 

corrosi~on.~ (In one converted flow coating operation, the only change was 

that the number of nozzles had to be doubled to obtain the same coverage as 

with conventional coatings.) 5 

The coating bath, flashoff time, temperature, air circulation, and 

humidity may have to be controlled and frequently monitored, because changes 

in weather conditions may affect the application of water-borne coatings. 6 

5.2 ELECTRODEPOSITION 

Several other advantages, in addition to reduced VOC emissions, accrue 

from converting to electrodeposi tion. 

The major one is improved quality control, a consequence of the fully 

automated process. 
It provides excellent and uniform coating coverage and corrosion 

protection because the paint particles are able to get into small recesses 

of parts;. 

Fire hazards and potential toxicity are decreased in electrodeposition 

due to the minimal organic solvent content. 

If electrodeposition replaced a spray coating operation, the solid 

and 1 iquid wastes associated with spraying operations wi 11 be reduced 

drastically. 

' The lower organic content permits lower ventilation rates, resulting 

in reduced energy consumption. 

There are some disadvantages to the electrodeposition process. 

Electrodeposition may increase electrical consumption. The'amwnt 

will depend on the original application system, the size of the electrodeposition bath, and the thickness of the coating applied. Electrical energy 

is required for the coating system, the refrigeration to overcome the 

temperature rise from the electri cal process, for good paint circulation 

in the bath, and to operate the ultrafi lter. Electrodeposition may consume 

three times as much energy in the application area as water-borne flow or dip 

coating operations.7 It does not, however, appear as energy inefficient 

when compared to a spraying operation because the high air volumes are no 

longer required. Energy consumption will also be less in the baking process. 

The air flow in the oven may be reduced and the flashoff tunnel may be 

omitted. 

A poor electrical connection will result in a poor coating (for 

example, if the hooks which hold the metal parts are not poperly cleaned or 

hung and inadvertently provide an electrical insulation, the quality of the 

coating will suffer.) 
The coverage is so uniform that electrodeposited coatings will not 

hide imperfections in the substrate. 

Conversion to electrodeposition will require a change of equipment 

at significant capital cost and can be relatively expensive on small 

scale production lines. 

5.3 HIGHER SOLIDS COATINGS 

One of the greatest advantages of converting to higher solids coatings 

as a means of reducing emissions of VOC is that they may be applied with 

little change to existing equipment. Some application equipment (i.e., 

spray guns) may have to be replaced or a paint heater may have to be 

installed to reduce the viscosity of the higher solids coatings but these 

are relatively inexpensive changes. Conversion to high solids coatings can 

reduce a plant's energy consumption. Air flow in the spray booth can be 

decreased because less organic solvent must be evaporated from a high solids 

coating when applying the same volume of coating. Since the energy required 

by the oven is largely dependent on the air flow (and it, in turn, is 

heavily influenced by the organic concentration 1 imitations imposed for 

safety reasons)8, the use of higher solids coatings will reduce energy 

requirements. Solid and liquid wastes may also decrease since less coating 

is applied per dry mil. However, the tackiness of high solid coatings may 

make cleanup more difficult. 9 

Some two-component high solids coatings may contain isocyanate compounds 

which are potentially toxic and must be handled and applied with caution. 

These also require instal lation of special application equipment. 

5.4 POWDER COATINGS 

There are several advantages obtained after a facility is converted to 

powder coatings . 
WOC emissions are almost completely eliminated. 

There are no solid or liquid wastes to be disposed of as compared 

to solvent-borne coatings. 

Powder does not require the purchase, or use of solvents to 

control the viscosity of the coating or to clean the equipment. 

' Powders can mask imperfections and weld marks. 

Conversion to powder coatings may reduce the energy requirements 

in a spray booth because the large volumes of fresh air required for 

appl ication of sol vent-borne coatings may not be required. Energy requirements for the ovens may also be reduced because little organics are being 

evaporated requiring less dilution. (It has been estimated that a 35-70 

percent overall reduction in energy requirements will result when a conventional single coat spray application is replaced with powder and 55-70 

percent reduction wi 11 occur for a two-coat spray application. ) 10 

The exhaust air from the spray booth can be filtered and returned 

to the working area. 

Up to 98 percent transfer efficiency of powder coatings can be 

realized since the overspray can be reclaimed. Not all overspray is always 

reusable, however, because a buildup of powder fines may have to be discarded, 

and the larger and heavier granules may have to be reprocessed again before 

they are suitable for reuse. 11 

There are several disadvantages to converting to the use of powder 

coatings. 

The conversion is non-reversible since a1 1 appl ication equipment, 

spray booths, and associated equipment (and often ovens) used for liquid 

systems must be replaced. This will then limit the flexibility of the 

faci 1 ity to apply other coatings. 
Coating film thicknesses of less than 0.9 mils have not been 

successfully obtained with powders on a production line basis, 

Metallic powder coatings are not as esthetically pleasing as conventional metal 1 ics. 

Color matching of a powder coating is difficult because its color 

cannot be changed by the applicator. Solvent borne coatings can be. 

Powder films have appearance limitations for some applications. 

Uncured powder coatings must be kept dry since their subsequent 

perf ormance can be affected . 

Powder coatings are subject to explosions (as are many particulate 

dusts). 12 

Color changes for powder require about half an hour downtime if 

powder is recovered for reuse. This may greatly curtail production 

capacities. Color changes may be shortened if powders are not reclaimed 

in their respective colors, but this results in a coating usage efficiency 

of only 50 to 60 percent. 

5.5 CARBON ADSORPTION 

Although the technology is well documented and considered technically 

feasible, there are not miscellaneous metal part or product facilities 

known to be using carbon adsorption systems to reduce organic emissions 

from coating application of flashoff areas. The energy required to operate 

a carbon adsorption system is a potential disadvantage. The actual quantity 

will depend on the size of adsorber(s) and the concentration of the solvents 

entering the carbon bed. Any reduction which can be made in the amount of 

air flow from the coating application and flashoff areas will permit 

purchase of a smaller adsorber with an attendant reduction in energy requirements. 
The amount of solid and liquid waste generated by the use of a carbon 


adsorber will depend on the type of coating application system. For 


example, emissions from flow and dip coating operations do not require 


filtration or scrubbing. Emissions from spray booths, however, may require 


pretreatment by fi 1tration or scrubbing since the overspray may foul the 


adswber bed. Water miscible solvents may produce a water pollution problem 


if the adsorber is regenerated with steam. This, however, can be avoided by 


incinerating the regeneration stream, by stripping the organics from the 


condensate or using nitrogen gas as a stripping medium. Each will increase 


the cost and energy consumption of a carbon adsorption unit. Since there 


is little possibility that the recovered solvents may be reused in the 

mi scel 1aneous metal part and product industries, any recovery or solvents 


would be for fuel value only. 


An important factor when considering instal 1ation of a carbon adsorption 


system is plant space. Large facilities may require many dual-bed carbon 


adsorption units in parallel which will need a relatively large area within 


the plant. 


5.6 INCINERATION 


The most common and widely applicable technique for the reduction of 


organic emissions is incinerat ion. Incinerators (or afterburners) have 


been used for many years for reducing organic emissions. One disadvantage 


is the quantity of additional fuel required unless heat recovery is used. 


The use of primary heat recovery to preheat the inlet gas stream to near 


in~iner~ation
temperature will minimize and can even eliminate fuel require- 


ments. If secondary heat recovery can be used for other energy-using 


processes, fuel requirements can be reduced even further. If there are 


enough areas where secondary heat may be utilized, an incineration system 

may even reduce the plant's overall fuel consumption. Table 5-1 shows the 

potent i a1 decreases in energy usage when using incinerators fol lowed by 

tube and shell heat exchangers with heat recovery efficiencies of 38 percent 

to 55 percent. Some examples where secondary heat from the incinerator 

exhaust may be used are: oven makeup air, boiler, cleaning processes, dryoff 

ovens, and plant room heating. Greater primary heat recovery efficiencies 

(80 to 95 percent) are shown in Table 5-2 using other types of heat exchangers 

such as ceramic wheel stone packed beds. These are reportedly very attractive 

even for low organic concentration streams because of their low fuel requirements. 
TABLE 5 -1 

BURNER REQUIREMENTS FOR INCINERATORS 

IN lo6 BTUIHRa,b,13 

NON-CATALYTIC INCINERATORS 5 percent LEL 1 5 percent LEL 

No Heat Recovery 

5000 scfm 

15,000 scfm 

30,000 scfm 

38% Efficient Primary Heat Re 

5000 scfm 

15,~000 scfm 

30,000 scfm 

Primary and 55% Efficient Secondary 

Heat Recovery 

5000 scfm 

15,000 scfm 

30,,000 scfm 

CATALYTIC INCINERATORS 

No Heat Recovery 

5000 scfm 

15,000 scfm 

30,000 scfm 

38% Efficient primary Heat Recovery 

5000 scfm 

15,000 scfrn 

301,000 scfm 

Primary and 55% Efficient Secondary 

Heat Recovery 

5000 scfm 

15,000 scfm 

3('1,000 scfm 

a) Based on 300'~ oven outlet temperature; 1400~~ outlet temperature for non-catalytic 

and 600°F inlet temperature for catalytic incinerators 

b) (-) indicates net overall fuel savings. 

c) These heat recovery efficiencies are based on sensible heat. 
TABLE 5-2 


BURNER REQUIREMENTS FOR NONCATALYTIC INCINERATORS 


WITH STONE PACKED BED HEAT EXCHANGERS 


in lo6 BTU/HR a,b,c,l4 


85% EFFICIENCY PRIMARY HEAT RECOVERY 5 percent LEL 15 percent LEL 


5,000 scfm 


15,000 scfm 


30,000 scfrn 


-

90% EFFICIENCY PRIMARY HEAT RECOVERY 5 percent LEL 15 percent LEL

5,000 scfm 


15,000 scfm 


30,000 scfm 


a) These heat recovery efficiencies include sensible heat and the heat of 


combustion of the VOC. 


b, Energy value of VOC used is 1.2 MM/BTU/HR per 10,000 scfm. 


(-) indicates overall fuel savings 
5.7 REFERENCES 

McCormick, Donald, "Converting a Flowcoater to Water-Borne Paint," 

Whirlpool Corporation. Presented at the NPCA Chemical Coatings 

Conference, Cincinnati, Ohio, April 23, 1976. 

Ibid. 

Water-Borne Flow coating and Dip, Products Finishing, pages 73-76, 

February, 1977. 

Products Finishing, Op. Ci t. 

McCorrnick, Op. Cit. 

Products Finishing, Op. Ci t. 

Kennedy, W. D., "Major Appl iance Electrocoat," Whirl pool Corporation. 

Presented at the NPCA Chmical Coatinas Conference, u 
 Cincinnati, Ohio, 

April 22, 1976. 

DeVi ttorio, J. M. , Ransburg Corporation, "Application Equi pment for 

High-Solids and Plural Component Coatings," Volume I, No. 2, April, 1976. 

"Question Corner," High-Solids Coatings, Volume I, No. 3, July, 1976. 

"Economic Justification of Powder Coating, " Powder Finishi ng World , pages 18-22, 4th Quarter, 1976. 

LeBras, Louis, Technical Director, PPG Industries, Inc. , Pittsburgh, 

Pennsylvania. Letter to V. N. Gallagher in comment of the metal furniture 

draft document. Letter dated August 31, 1977. 

Ibid. 

Combustion Engineering Air Prehater, We1 1 sville, New York. Report of 

Fuel Requirements, Capital Cost, and Operating Expenses for Catalytic 

and Thermal Afterburners, EPA Contract Report No. EPA-45013-76-031, 

September, 1976. 

Mueller, James H., Regenerative Environmental Equipment Co., Inc., Morris 

Plains, New Jersey. Letter to V. N. Gallagher in coment of this draft 

documenlt. Letter dated March 31, 1978. 
6.0 MONITORING TECHNIQUES AND ENFORCEMENT ASPECTS 

This chapter discusses the recommended emission limits, the monitoring 


techniques and enforcement aspects for both coatings which are low in organic 


solvents and add-on control equipment. 


Limitations in VOC may be expressed in terms of mass or volume and 


may be based on the entire coating (including organic solvent) or only on 


paint solids. In this guideline, limitations are expressed as the allow- 


able mass of organic solvent per unit volume of coating (kgs per liter of 


coating or Ibs per gallon of coating - minus water) as it is delivered to the coating 

applicator. The water content of the coating is not included in the ratio. 


The principal advantage of this format is that enforcement is relatively 


simple. Field personnel can draw samples and have them analyzed quickly. 


A disadvantage is that the relationship between the solvent fraction and 

organic emissions is not linear. If the organic solvent content is expressed 


in terms of mass of organic solvent per unit volume of paint solids (kgs per 


liter or lbs per gallon of solids), the disparity disappears. This relationship 


is linear and more readily understood, e.g., a coating containing 2 Ibs of 


organic solvent per gallon of solids releases twice as much organic solvent 


as one with one pound per gallon. The disadvantage of this format, however, 


is that the analytical methods are more complex. Appendix A of Volume I1 

of this series, "Control of Volatile Organic Emissions from Existing Stationary 


Sources - Volume 11: Surface Coating of Cans, Coils, Paper, Fabrics, 

Automobiles, and Light-Duty Trucks," presents ASTM test methods that permit 


determination ~f the organic solvent per gallon of coating (minus water). 

For miscellaneous metal part and product coating facilities, it is 

recommended that, if possible, emission limitations should be expressed 

in terms of the organic solvent content of the coating since these values 

can be determined with relatively simple analytical techniques. Alternative 

compliance procedures should permit operators to use add-on control equipment if they so choose. (Sample calculations to verify compliance with 

this type of emission 1 imit are shown in Appendix A of this document .) 

Other options such as mass or volume of organic solvent per mass 

of coating are generally less desirable although they may be entirely 

appropriate for a given industry. Basing limitations on the mass of 

coating or paint solids is not generally recommended because the specific 

gravity of a coating solids tends to vary widely with the degree and type of 

pigment employed. Highly pigmented paints have much greater density than 

unpi gmented clear coats or varnishes. 

The recommended limitations assume the miscellaneous metal part and 

product facilities merely convert an organic-borne coating to a coating 

low in organic solvent. They do not consider the reduction in VOC emissions 

which would result from a decrease in film thickness or an increase in the 

transfer efficiency of a coating. For example, assume a facility applying 

conventional coating at 1.2 mils film thickness, converts to a coating 

which, although it contains less organic solvent, does not quite meet the 

recommended emission limit. If the new coating is serviceable when applied 

in a thinner coat, it may result in a reduction in VOC emissions comparable 

to or even greater than a coating which meets the recommended emission limit. 

Another example would be the emission reductions that accrue from 

improved coating techniques. A facility that converts from a conventional 

manual spray application (at a transfer efficiency of 40-70 percent) to an 
automated electrostatic spray system (at a transfer efficiency of 70-90 


percent), or from any spray system to a flow or dip coat system (at a 


transfer efficiency of at least 90 percent) would realize a significant 


reduction in VOC emissions. All of these possibilities should be considered 


in any evaluation of the overall reduction achieved by the operator. 


In those few faci 1 i ties where add-on control equipment is a more 


likely option, it may be more appropriate to state emission limits in terms 


of control efficiency across the incinerator, adsorber, etc. Otherwise, 


where limitations are expressed only in terms of the solvent content of the 


coating, it would be necessary to determine the mass emission rate from the 


control system and relate it to the quantity of coating applied during 


the test period. This is a more complicated procedure since it may not be 


easy to determine the amount of coating consumed during the test period and 


an analysis by mass of the organic solvent directed to the control device 


would be even more difficult. Chapter 5 of "Control of Volatile Organic 


Emissions from Existing Stationary Sources - Volume I: Control Methods 

for Surface Coating Operations" presents approaches which may be used. 


When add-on type devices are selected as the compliance method, the air 


pollution control agency should require that the coating lines be equipped 


with an approved capture device to assure effective containment. The capture 


system will likely have to be custom designed to accommodate the individual 


plant ~(ariables which affect performance. When reviewing the design of such 


a system, however, the air pollution control official must also consider 


requirements imposed by the Occupational Safety and Health Administration 


and the National Fire Prevention Association. 


It is recognized that some coatings will emit more VOC than merely its 


solvent content. This incremental VOC may come from three possible sources. 

The first. is the possibility that some of the monomer may evaporate. Also, 


if the film forms by condensation polymerization, the evolution of by-products 


may be a compounding factor. Finally, it has been reported that the industry 


is using increasing quantities of "blocking agentsi' which are released fram 


the polymer matrix during the curing process. 


There are now no approved analytical methods certified by the agency 


for determining the quantity of VOC emitted by such reactions although 


certainly the organic mass emission rate could be determined by expensive 


and sophisticated analytical techniques. The more practical means of 


quantifying the contribution of the polymerization reaction to the overall 


emission problem would be by contacting the manufacturer of the coating. 


Certainly, his knowledge of the fundamental chemical mechanisms involved 


would at low calculation of an emission rate based on the chemical reaction. 

This emission will occur during the cure (if at all) which is usually 


temperature initiated by the oven. If the oven is controlled by an incinerator, 


then verification of the efficiency of the device should be sufficient to 


assure compliance with the coating regulations. 

APPENDIX A 


SAMPLE CALCULATIONS OF CONTROL OPTIONS 


This appendix will aid the local agency in determining if a coating 


proposed for use by a miscellaneous metal part or product facility will 


meet a recommended emission limit. It also explains how to compare the 


actual VOC emissions from a facility regardless of the type of low-polluting 


coating or add-on control device used. 


The purpose of all coating operations is to cover a substrate with a 


film that provides both corrosion resistance to the substrate and 


esthetic appeal. Therefore, the rational basis for specifying an a1 lowable 


VOC emission limit would be in units of coating volume (e.g., grams of 


VOC per square meter (lbs/sq. ft) per unit thickness of film). However, 


the complexity of any analytical method which would provide a measurement 


of the volume of a cured coating precludes this approach. As a compromise, 


the limitations were developed in terms of mass of VOC per unit volume of 


uncured solids and organic solvent. Mathematically, then, the emission 


factor (ef) for a coating would be expressed as: 


) ef = (volume fraction organic solvent) (average organic solvent density) 

volume traction of solids + volume fraction ot organic solvent 

,, 
( 2) ef = (volume fraction organic solvent) (average organic solvent density) 

1- volume fract~on of water 


The following examples show the use of these equations to determine 


the emission factor for both organic solvent-borne and water-borne coatings. 


We will assume the applicable emission limitation is 0.34 kg/liter. This 


represents a low solvent coating with 0.62 v/~
 solids content. 


A-1 
CASE 1: Determine the emission factor for an organic solvent-borne coating 


which contains 35 volume percent organic solvent. 

Therefore: ef = (.35)(0.88 -kg/liter*) 

= 0.31 kgs/ 1i ter (2.6 lbslgal) 

Since the emission factor is less than the recommended limit of 


0.34 kglliter (2.8 Ibs/gal), th is coating is in compliance. 

CASE 2: Determine the emission factor for a water-borne coating containing 

25 volume percent sol ids. Of the 75 percent solvent,' '80 volume percent 

is water and 20 percent is organic solvent. 

Since 80 percent of the solvent is water, the respective volumes of 

water and organic solvent may be calculated as shown: 


Volume water = .80 x .75 liter = .6 liter 

Volume organic solvent = 0.75 liter - .6 liter = .15 liter 

-

= 0.32 kglliter (2.64 Ibs/gal) 

This coating also has an emission factor less than the recommended limit 


and would comply. 


The level of control represented by 0.34 kglliter of coating 

(2.8 'lbslgal) less water can also be achieved with a conventional high 

organic solvent coating if suitable add-on control equipment is instal led. 


However, this method of determin ing the equivalent emission limit factor 


is not as straightforward as the previous two cases and must also consider 


the volume of solids in the coat ing. 


CASE 3: Determine the emission factor for a conventional organi c-borne . 

coating containing 75 volume percent organic solvent. 

*[his density is considered typical and is equal to 7.36 lbslgal. 
= 0.66 kg/liter (5.5 Ibs/gal) 

However, this liter of coating contains only 0.25 liter of solids 


whereas the low-solvent coating which the recommended emission limit of 


0.34 kg/liter (2.8gal ) represented would contain 0.62 liter of solids. 

(The fraction of solids in the low solvent coating can be back calcu- 


lated from the recommended emission limit in the following manner.) 


i.e., 0.34 = (~)(0.88kglliter) 1-0 


x = 0.38, volume percent organic solvent 

Therefore, fraction of solids = 1 - x = 0.62. 

On a unit volume of solids basis, the conventional coating contains: 


0.66 kg organic solvent - 2.64 kg organic solvent or22 Ibs VOC 

0.25 liter solids liter solids gal solids 


And the recommended 1 imi t reference coating contains only: 


0.34 kg organic solvent - 0.55 kg organic solvent or 4.6 lbs VOC 

0.62 liter solids liter solids gal solids 


Consequently, in order for a facility to use the conventional coating 


yet emit no more VOC than the reference coating, the add-on control device 

must capture and destroy (or collect) 2.09 kg of solvent per liter of solids 


applied (2.64 - 0.55). This will require a control system that is at least 

79 percent efficient. Since the add-on control devices can often operate 


at 90 percent efficiency or greater, the agency must insure that at least 


88 percent of the VOC emitted by the coating is captured and delivered to 


the add-on control device. Since it will often not be practical to 


attempt the complex analytical program essential to develop a material 

balance around the coating application and flashoff areas and ovens, 

the agency may certify an acceptable capture system based on good 

1 engineering practice. 

APPENDIX A REFERENCE 

1. Young, Dexter E: , Environmental Protection Agency, memorandum 

concerning requirements for ventilation of spray booths and 

ovens. Dated March 10, 1977. 
I 

TECHNICAL REPORT DATA 

(Please read Iurtlztctlons on the reverse before completing) 

1. REPORT NO. 2. (3. RECIPIENT'S ACCESSIOWNO. 

I -

Control of Volatile Organic Emissions from 

Stationary Sources - Volume VI: Surface 

Mi scel laneous Metal Parts and Products 

8. PERFORMING ORGANIZATION REPORT NO I Vera Gal lagher, John Pratapas I OAQPS No. 1.2-101 

NAME AND ADDRESS 10. PROGRAM ELEMENT NO. 

U.S. Environmental Protection Agency 

office of Ai r and Waste ana age men t 11. CONTRACTIGRANT NO. 

Office of Air Quality Planning and Standards 

Research Tri angle Park, North Carolina 27711 

NAME AND ADDRESS 

14. SPONSORING AGENCY CODE I 

15. SUPPLEMENTARY NOTES 

16. ABSTRACT 

This document provides the necessary guidance for development of 

regulations to limit emissions of vol ati le organic compounds (VOC) from 

the coating operations of m i scell aneous metal parts and products. This 

guidance i,ncludes emission 1 imi ts which represent Reasonably Avai 1 able 

Control Technology (RACT) for the miscellaneous metal part and product 

industries, describes the industries, shows the methods by which VOC 

emissions can be reduced in these industries and describes the monitoring 

and enforcement aspects. 

KEY WORDS AND DOCUMENT ANALYSIS 

DESCRIPTORS ~.IDENTIFIERS/OPENENDEDTERMS c. coSATlField/Gro~p 

Air Pollution Air Pollution Control 

Miscell aneous Metal Part and Product Stationary Sources 

Industries 

Vol ati le Organic Compound Emission Organi c Vapors 

L im i t:s I Regulatory Guidance I I 


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