UnitedStates Officeof Air Quality EPA-450/2-78-015 Environmental Protection Planning and Standards OAQPS No. 1.2-1 01 Agency Research Triangle Park NC 27711 June 1978 Air CW.TING 

# Guideline Series OTHER METAL P.P- 42 Section 4.2.7.9 Reference Number 

# Controlof Volatile Organic Emissions trom tx~stmg StationarySources
- Volume

# VI: Surface Coatingof Miscellaneous Metal Partsand Products

### EPA-450/2-78-015 (OAOPS

### NO.1.2-101)



# CONTROLOFVOLATILE ORGANIC EMISSIONS FROMEXISTING STATIONARYSOURCES VOLUMEVI: SURFACECOATING OF MISCELLANEOUS METALPARTS AND PRODUCTS

Emissions Standardsand Engineering Division Chemicaland PetroleumBranch

U.S. ENVIRONMENTALPROTECTION AGENCY OfficeofAir, Noiseand Radiation OfficeofAir QualityPlanningandStandards ResearchTriangle Park, NorthCarolina27711 June 1978PREFACE
This document isone 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 isintended 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 inthis series. Reports have already been publishedwhich 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 inthis broad industria1 category, identifies the sources and types of VOC emissions, and reports the availablemethods and costs for minimizing these emissions. Monitoring techniques for coatings which are low inorganic solvents are suggested. More detaileddiscussionsof coatings low inorganic solvent and add-on control technologies are found in, "Control of Volatile Organic Emissionsfrom ExistingStationary Sources

# - Volume I: Control Methods for Surface Coating Operations,

### " EPA-45012-76-028, November, 1976. ASTM test methods for monitoring the organic solvent content of coatings are summarized in, "Control of Volatile Organic Emissions from Existing Stationary Sources

# - Volume 11: Surface Coating of Cans, Coils, Paper, Fabrics, Automobiles and Light Duty Trucks," EPA-45012-77-008, May, 1977. *Earlier volumes inthis series are available from the National Technical Information Service.

iiiOAQPS GUIDELINESERIES Theguidelinesseriesof reportsisbeing issuedbytheofficeofAirQuality PlanningandStandards (OAQPS)to informationtostateand local air pollution controlagencies;for example,toprovideguidanceon the acquisition andprocessingof air qualitydata andonthe planning andanalysis requisite forthe maintenceof air quality. Reportspublishedinthisserieswillbeavailable-assuppliespermit-fromthe Library ServicesOffice(MD-35). U.S. EnvironmentalProtectionAgency, ResearchTrianglePark,NorthCarolina27711;or,foranominalfee,from the National'TechnicalInformation Service, 5285 Port Royal Road, Springfield, Virginia 22161.

Publication No. EPA-450/2-78-015 (OAQPSNO.1.2-101)The miscellaneous metal part and product category includes hundreds of small tomedium 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 avai1able control technology (RACT)

# . Reasonably available control technology 

### is defined as the lowest emission limit that a particular source iscapable of meeting by the application of control technology that isreasonably avai1 able considering technological and economic feasibility. Itmay require technology that has been applied to similar, but not necessarily identical source categories. Itis not intended that extensive research and development be conducted before a given control technology can be applied tothe 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 isan appropriate technology forcing aspect of RACT. The diagram
on the next page provides emission limits that represent RACT forthe industries included in themiscellaneous metal parts and products category of the surface coating industry. Itmust be cautioned that the limits reported inthe diagram are necessarily based on a general consideration of the capabilities and problems of the hundreds of industries whichcoattheir products. Itwill not be applicable to every plant or even every industry within themany industries which coat. For example, the level of control which 

### is herein recommended for
a particular sourcemay be based on a type of coating which cannot meet the specifications required of another product from a 

### simi1 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) tiveheat requirements. Parts to which heat sensitivematerials are attached. Equipment assembled prior to top coating for specific performance or qua1ity standards.

No or infrequent color chanae or small number of colors applied

## .

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 iter (3.0 lbs/gal performance applied, or first coat on .4 lbs/gal) characteristics untreated ferrous substrat

# 4

0.42 kg/liter 0.36 kg/liter 

# k

(3.5 lbs/gal) ,(3.0 lbs/aal)
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 to0.52 Kg per liter (0.4 to 4.4 Ibs/gal). Equivalent reductions inVOC 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 tomeet future VOC regulations through the use of coatings low inorganic solvents rather than resort to add-on control devices.GLOSSARY Single coat means only one filmof coating isapplied tothe metal substrate. Prime coat means the first of two or more films of coatins applied inan operation. Topcoat means the final filmor series of films of coating applied in a two-coat (or more) operation. Faraday caging means a repellingforce generated incorners 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 isdesigned 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 to2000F). Transfer efficiencymeans the portion of coating which isnot 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 following formula:

tof = temperature in degrees Fahrenheit
to = temperature in degrees Celsius or degrees Centigrade C Kg. per liter x 

### 8.34 = lbs/galTABLE OF CONTENTS

PREFACE 

# ............................... GLOSSARY

# ............................... CONVER.SIONFACTORS 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 forAnnualized 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 (Electrodeposition) 

# .............. 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 TECHNIQUESAND ENFORCEMENT ASPECTS

# .......... 6-1 APPENDIX A 

## .SAMPLE CALCULATIONS OF CONTROL OPTIONS ;

# ........ A-1 APPENDIX A 

## . Reference

# ........................ A-41.0 

### SOURCES

### AND TYPES OF EMISSIONS



### This chapter provides general information on the miscel

### 1aneousmetal parts and products industries, themethods 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 ofmetal parts and products are coated for decorative or protective purposes. These are grouped into hundreds of small industria1 categories forwhich writing individual guideline documentswould be unreasonable. This guideline document is intended to provide information on industries which coatmetal 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 forwhich this guideline is intended and some examples of each category are listed in Table 

### 1.1, There are farmore 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 farmmachinery are located primarily in agricultural areas of the country such as 

### EPA Regions 

### V and 

### VII. Others, like small appliancesmay be scattered throughout the countryTable 

### 1.1 LIST OF INDUSTRIAL CATEGORIES COVERED 

### BY

large farmmachinery (harvesting,ferti1izing and planting machines, tractors, combines, etc.) small farmmachinery (lawn and garden tractors, lawn mowers, rototillers, etc.) ma1

### 1 appliances (fans, mixers, blenders, crock pots, dehumidifiers, vacuum cleaners, etc.) commercia1 machinery (computersand auxi

### 1iary equipment, typewriters, calculators, vending machines, etc.) industria1 machinery (pumps,compressors, conveyor components, fans, blowers, transformers,etc.) fabricatedmetal 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.ta1industries), Major Group 

### 34 (fabricated metal products), Major Group 

### 35 (non-electrical machinery), Major Group 36 (electrical machinery), Major Group 37 (transportationequi ment), Major Group.38 (miscel~aneous 

# e instruments), Major Group 39 (misce laneous manufacturing ~ndustr~es), ;.lajorGroup 40 (railroad transportation) and Major Group 

### 41 (transit passenger transportation).


### 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 facilitiesmanufacture and coat metal parts, then assemble them to form a final product to be sold directly for retail. 0thers.oftencalled "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 facilitiesare 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 industriesbut also within each industry. Two facilities coating the same product may apply different coatings using completely different applicationmethods. 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 themetal coating industry. In many cases the coatingsmust provide esthetic appeal, but in all cases, theymust protect themetal 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 themany industries considered by this document. Both enamels (at about 30-40volume percent solids) and lacquers (at 10-20volume 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 a1kyds, acrylics, epoxies, polyesters, vinyls, si

### 1icones,

### plastisols and phenols. Most coatings contain several (up to 10) 

### different solvents. Typical solvents are ketones, esters, alcohols, a1iphatics, ethers, aromatics and terpenes

# . 1.2 

### PROCESSES AND EMISSION POINTS Each meta1 

### coating line tends to be somewhat unique because of its age, product coated

### ,design, and application technique. Figure 

### 1.1 portrays
common features found inmany 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-coatoperations. Thesemethods typically include spray,dip, or flow coating for both single coats and primers. Spray is usually used for the topcoat. First themetal substrate is cleansed to remove grease, dust.,mill scale or corrosion. Often it is pretreated to improve adhesion. Themost common method is the five stage cleansing process where themetal 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 pretreatmentsmay also be used. Other cleaningmethods are also used. Theparts may be 

### cleaned in a shot-blasting chamber by using organic solvent cleansers. (SeeControl of Volatile Organic Emissions from Solvent Metal Cleaning) Themetal often passes through an oven to remove water before the coating is applied. Spraying is themore 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 (whichmay 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 systemwhich

. 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 applicationsmay also be applied by dipping. Themetal parts are briefly immersed eithermanually 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. Thismethod also provides about 

### 90percent 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 systemwill---- -- 

### depend on the size of the dip tank. Spraying is the most common technique for applying single coat, some primer and most topcoat applications. 

### Itprovides a transfer efficiency of 

### 40 to 70percent. Electrostatic sprayingwith 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 inwhich the coating is applied. The spraybooths 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 ormulti-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 

### 45mpm (50to 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 flowdoubles the organic concentration and reduces the capital and operating cost of add-on control equipment. Air curtainsmay be used at the openings to sweep the openings and minimize the air volume required to contain the emissionswithin the oven.-- - - 

### Flow diagram c 

### of Figure 

### 1.1 shows amanual 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 coatingswould not be economically feasible. Formany 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, gas01ine, chemical spi

### 1ls, fertilizer, moisture and other miscellaneousexposures. The assembled unit is cleaned to remove dirt, grease, ormill scale. The unit is usuallymoved to another roomwhere 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 roomswhich may be often as large as 8

### x 8

### x18 

### 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 itemsmay even be coated outdoors. 

### In summary, organic emissions from the coating of miscellaneousmetal 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 ratewith isopleths of organic concentration in terms of the 

### LEL. It emphasizes the 

### effect of solvent concentration on the volume of exhaust gasesthat 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 flowrate, 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 themost difficult combination of circum- stances. As a result, the rate may be excess ofmany 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



### PERCENTOF 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 aVOC 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 re1ationship between VOC emission, exhaust f18wrate and VOC concentration.2.0 APPLICABLE SYSTEMS OF EMISSION REDUCTION
This chapter discusses coatings low inorganic solvents (LOSC) and add-on equipment for the control of VOC from conventional coating applications used inthe 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.1ication Organic Emissions Water-Borne (spray, dip Oven baked single coat, 60-90" or f1 ow coat) primer and topcoat; air dried primer and topcoat Water-Borne Oven baked single coat 90-95a (electrodeposition) and primer Higher-Solids (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 inreductionpossible. The actual reduction to be achievedwilldepend on the composition of the coating and the replacement low organic solvent coating, transfer efficiency and the relativefilmthicknesses of the two coatings. b~his reduction inVOC emissions isonly 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 issimilar to organic solventborne coatings thus conversion towater-borne coatings does not necessarily require extensive replacement of the existing coating application equipment. A reduction of 60 to90 percent inorganic emissions may be achieved by switching towater-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 ilmthicknesses required. The transfer efficiency of water-borne coatings issimilar tothat of conventional coatings. A1though water isthe major carrier, some organic solvents must be included totemper 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 inVolume I, Sections 3.3.1 and 3.3.5.'
2.2 WATER-BORNE (ELECTRODEPOSITION) Although converting toelectrodeposited water-borne coatings wi11 require new application equipment (i .e., tank, ultrafilter, rinsing stations, etc.), it results inincreased 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 filmthickness may be adjusted by voltage and immersion time.

### Farm and commercial machinery, and fabricated metal product facilitieshave been reported to apply coatings by electrodeposition.

### 4 

# '
One major advantage of water-borne coatings is that, unlike solvent-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 15volume 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 solidswith somewater and trace quantities of organic solvent. These solvents control the flow of the coating during the curing process. Theparts are then rinsed in several stages to remove any excess paint. (Therinse is then ultrafiltered to remove thewater and organics. The paint solids are returned to the bath.) A complicating factor in determining the emission factor for electrodeposition is the very limited informationnow available on the final disposition of organic solvent. 

### If the emission factor considers only the coating applied to themetal substrate (which would be emitted from the oven), it is only about 0.024 

### to 0.06 

### ka/liter (minuswater). 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 lesswater. Certainly, however, with--- 

### effect of improved transfer efficiency included, use of electrodeposited coatings
can reduceVOC emissions by at least 90 

### to 95percent over conventional coatings. Electrodeposited coatings are normally baked at 150-200'~ (257-400'~) 

# . Research is currently underway to eliminate the intermediate baking step now used to cure electrodeposited primers prior to topcoat application. Both the primer and topcoatwould 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 electrodeposition coating technology, seeVolume 

### 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, Coatingswith even greater solids content (60

### to 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. Thesewill 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, ormanually. The first two are the
more efficient applicationmethods. 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 thanwith conventional solids coatingsparticularly with electrostatic sprays.7 

### Further technical details on the use of high-solids coatings may be found in Volume I, 

### Section 

### 3.3.2. 82.4 

### 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 

### 5mils, and thicknesses of much less than 1mil have been achieved on experimental interior
can lines. Powder coatings are also applied by dipping but the resultant film ismuch thicker, a minimum of about 6

### mi1s. After application of the coating, themetal 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

## ,a1though different equipment must be used. Film thickness can be controlled by the voltage potential. Powder coatingswrap 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 we11. 

### 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 theones 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 oneyear 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 thewinter months. Changing colorswhen 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 thoroughlyto avoid color contamination. This will require greater downtime. Twomethods have evolved forminimizing the time required to change colors. Some facilitieshave several overspray recovery units available that may easily be attached to a single spraybooth. Others have installed several mobile spray booths and associated recovery equipment1' to minimize the number of changeoversthat must be made. Still another approach has been to use themulticolored overspray on parts that do not have critical color specifications. A1though 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 sinceno 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 coatingmiscellaneousmetal 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 emissionsby 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 miscel1

### aneous metal parts or products. Carbon adsorption is technically feasible for these applications13 (nonew inventions are required for its implementation), but pilot studiesmay be necessary before this control technology is installed. 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.tileorganic 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 themost universally applicable control system for VOC. There are no serious technical problems associated with the use of either catalytic or noncatalytic incineratorson miscellaneous metal product coating facilities. Incineratorheat 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 materialswill 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 coldermonths. Incineration of the exhaust from application and flashoff areasiscertainly technical1y 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. 162.7 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. (formerlyDeBell 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 a1ternative ways of control1ing solvent emissions at existing coating lines in themetal 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- trol1ing volatile organic compounds (VOC) from application areas and curing ovens associated with conveyorized single-coat lines and con- veyorized two-coat lines. Control costs formanual 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:A1ternative 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 solids (60 percent or above) content 2. Use ofwaterborne coatings 3. Powder deposition 4. Electrodeposi tion (EDP) A1ternative 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 1ines. Coating rates analyzed for conveyorized si ngle-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 is2880 hours/yr. Itmust be emphasized that model coating lines used inthis analysis are very simple inthat they involvea one-color, single-coat or two-coat application. Analyzing multicolor coating systems isbeyond the scope of this analysis. Also, although control cost estimates based
on the model plant approach may differ from actual costs incurred, theyare nevertheless considered the best means of comparing relativecosts and cost effectiveness ofalternative control measures. 3.1.4 Bases for Capital Cost Estimates Capital costs represent the investment required for retrofittinga control system, including costs ofequipment, material, labor for installation, and other associated costs. Capital cost estimates are based on cost surveys ofvarious installations presented inthe references (1, 2). Most of the surveyed costs represent new installations. These costs have been modified toapply to retrofit installations. All capital costs are expressed inmid-1977 dollars. Inaddition 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 forAnnualized 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., lineconversions, are incremental costs incurred inconverting from high-solvent to 1 ow-solvent coatings. The bases for these projected incremental costs are available inthe referenced material (1, 2). Again, itmust be emphasized that these analyses ofmodel coating lines are provided as
a means of comparing the relative costs ofalternative control measures. Various coating industries have devoted considerable resources to the development of incremental costs of low-solvent coating conversions.

### However, a comparisonof these estimatesmay 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,rawmaterial costs,and coating specificationswi

### 11 inf1

### uence these incremental costs. General cost factors used to estimate annualized costs formodel coating lines are provided in Tab

### 1e 3-1. 3.2. SOLVENT EMISSION CONTROL INMETAL COATING OPERATIONS 3.2.1 Model Plant Parameters Table 3-2presents 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 efficienciesare based on typical practice. Add-on control systems can provide overall emission control effi

# - ciencies of the order of 80 

### to 90 

### percent. Separate control systemsare assumed for application/flash-offareas and drying ovens. Emission control efficiencies forprocess 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 considerationhas been given to detailed design characteristicsof 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 andTable 3-1. 

### COST FACTORS USED IN COMPUTING ANNUALIZED COSTS

-

I. Direct operating costs 1. Materials (as purchased):



### - Conventional prime coating (40%solids)a



### - Alkyd conventional top coating (40%solids)



### - Solvent thinner



### - Polyester high solids coating (60% solid^)^



### - Alkyd waterborne coating (40% solid^)^



### - Epoxy powder coating

- Electrodepositionwaterborne (60%solids)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) $2.1111iter ($8/gal) $0.28/liter ($1.O7/gal) $3.17/1 iter ($12/ga1) $2.38/1 iter ($9/gal) $3.30/kg ($1.5011b) $2.9l/l iter ($11.O/gal)

$0.03/kw-hr $1.9O/GJ ($2.00/mill ion Btu) $5.50/thousand ($2.50/thousand $1O/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 costTab1e 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 coatoven



## - Dip coat booth



## - Dip coat oven



## - Spray coat booth



## - Spray coat oven Manual two-coat operation 2 2 Line size, m Iyr (ftlyr) 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 solvent 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 a1ternatives 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-effectivenessof different options. 3.2.2 

### Control Costs Table 3-3through 3-9

### present details of control cost estimates for seven coating operations. Tables 3-3, 3-4,and 3-5present 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-coatoperation. Capital costs of converting 1

### ines to higher-solids coatingsor to waterborne coatings are those re1ated to appli

### cation equipment modifi- 

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

### percent ormore solids content) coatings,particularly a high speed turbine be1

### 1 or disc high-sol ids coating, requires installation of new pumps and fluid transfer equipment. The cost estimates include this equipment (5). 

### Capital cost estimates change radically 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 applicationand 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 1abor0

. 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 C U .- .- al 2,- LLC D m u U mv- al C'C s .u '- hS m Lo- O * 22.5
nuw 4 L u-0 4 t U w 1 u u 3 m L 0 Y a-s PCL m c > moo r ULhk .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)

Applicable control option

Cost itern Waterborne nediu 

## - - sma1


## - )sting! Lea large


## - Electrodeposition(EOP) KElx nediurn



### - :- large A

small 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 cryb recovr mediurn Ize large Thermal incineration with 90%primary heat recover# ze large urce 

### - redi ur 

## - - sma1


## -

- - " 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 controlled. WY r 6 35 69 7 39 7 39

O Emission reduction. X 80 80 80 90 90 90 90 Cost effectiveness (credit),

$/Mg of solvent controlled 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. 

## * Incrmntsofwaste disposal costs, labor costs, and labor overhead are insignificant; these are not included inthe annual costs.- - Table 3-5. INCREMENTAL COSTS OF SOLVENT EMISSION CONTROL OPTIONS FOR CONVEYORIZED SINGLE-COAT OPERATION, SPRAY-COAT APPLICATION (Mid-1977 thousand do1lars)

Applicable control 0~tion 1 arbon adsorptton and rbon adsorption and hem1incineration talytic tncineration henna1 incineration 4th 352 prt 

### "%ryheat th352 pri "gryheat ti th902 pri -y heat recovery recovery recover aterborne GI oat:I nga High solidscoatings Powder deposition

-I source size

## - sou e siz OUI L rce s L lrge iGaiiimlrge sMll Kii arge 5 rrge 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 12 130 12 2 4 6 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

# lii

(credit) " Solvent emissions controlled, 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 6386


## - - a see Table 3-2 for source sizes.

Carbon adsorption on spray-coat booth and incinerationwith 35 percent primary heat recovery on drying oven. Thermal incineration with 90 percent primary heat recovery on spray-coat booth and drying oven. Increments ofwaste disposal costs. labor costs, and labor overhead are insignificant; these are not included inthe annual costs.Tabie 3-6. 

### INCREMENTAL COSTS OF 

### SOLVENT EMISSION CONTROL OPTIONS FOR EONVEYORIZED TWO-COAT OPERATION, FLOW-AND SPRAY-COATAPPLICATION (Mid-1977 thousand do1lars)

Applicable control option.arbon adsorption and

Cost item 1 Waterborne coz ktings L 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 "g recoverv 

### 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 controlled. WY r 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 90percent primary heat recovery on coating booth and drying oven. Increments ofwaste 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 do11

### ars)

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%pri

### 9 ryheat 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 controlled,

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 dryingoven. 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 inthe annual costs.Tab1e 3-8. COSTS OF SOLVENT EMISSION CONTROL OPTIONS FOR CONVEYORIZED TWO-COAT OPERATION, SPRAY-COAT APPLICATION (Mid-1977 thousand do1lars)

A991icable 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^ 4th35% primary heat recoveryb 2 Thermal incineration with 90% primary heat recoveryC source size

- Cost item sma1 nediun large 

## - small nediun 

## - small medium large small 

## - arge 

# - smal1 

## -

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 controlled 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 90percent 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-1977 thousand do1lars)

Applicable control option IThennal incineration Waterborne ( E L 5 )stings r e Carbon adsorption source size with 90%primary heat recovery source S I ~ Cost item iediun small 

## - lediun small lmedium)large arge 

# - smalllmedium 1 arge 

## - I 1 " 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 inthe annual costs.

### savings are estimated for powder coating conversions (1,2); however, a higher coating thickness of 50 urn (2

### mils) assumed forpowder coating diminishes possible savings. For electrodeposition, lower applied film thickness helps override
some of the associated increased electrical costs (1). 

### Annualized costs of incinerationof oven emissionsprimarily 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 formanual two-coat operation. These curves represent the effect of line size on the costper unit weight of solvent controlled. The cost per unit weight of solvent controlled decreases with the increasing line size in a11 cases. The twomost cost-effective options evaluated for conveyori zed single flow-coatand single dip-coat operations appear to be conversion 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-effectiveoption for spray coating in a conveyorized single-coat operation; carbon adsorption combined with thermal i

### ncineration, with 35 

### percent primary heat recovery is themost 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 ApplicationWATERBORNE 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

5 105 2

COATING RATE, 10 m /year

FIGURE 3-2. Cost-Effectiveness Comparison of Solvent Emission Control Options Conveyorized Single-Coat Operation Dip-Coat ApplicationWATERBORNE 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 ApplicationWATERBORNE COATINGS 

### nCARBON 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 Conveyorized Two-Coat Operation Flow- and Spray-Coat ApplicationWATERBORNE 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. Cost-Effectiveness Comparison of Solvent Emission Control Options Conveyorized Two-Coat Operation Dip- and Spray-Coat ApplicationFIGURE 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 UIZ 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 

### lyear

### 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 OperationConversion to a powder-coating process isthe 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 isthe least costly option evaluated for manual two-coat operations. Again, add-on control systems cost much more than process changes. Inflow and dip coating inconveyorized single-coat operations, thermal incinerationwith 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 inall other operat ions (spray-coating inconveyorized single-coat operations and all coatings inconveyorized twocoat operations); however, it isthe 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 withcatalytic incineration at30 percent primary heat recovery. The carbon adsorption system appears to be more cost-effective than thermal incineration, with 90 percent primary heat recovery on manual two-coat operations. 

### * Thlermal incinerationwith 90 percent primary heat recovery isapplied on coating booth and drying oven. 

## + Ca~rbonadsorption on booth and thermal/catalytic incineration on drying oven.3.4 SUMMARY Cost analyses of the model lines indicate that modificationofthe coating process toa low-solvent coating usually appears to be more cost--effectivefor control ofVOC than add-on control. However, because annualized costs for a1ternative coating systems are greatly affected by assumptions implicit inthe 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,yof 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, Pennsylvania

## . 1973. 5. Information supplied to U

## .S. EPA by Regenerative 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 (OAQPSNO. 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 SelectedAir 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 agencymay use the logic diagram presented
as Figure 4.1 to develop a standard appropriate for almost any coating process which applies surface coatings on ametal substrate. Theprocedure for determining emission limits which represent the presumptive norm achievableby 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. Unti1 

### reaching a block that presents the level of 

### control that is presumed to be ach of 

### RACT by themanufacturer. As 

### an example, to find the recommendedievable through the application

emission limit for a continuousoperation 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 ovenwhen coated, so proceed to node C. ' 

### The brackets aremarketed 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. Thiswould then be the level of control presumed to representRACT 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 a11 

### the specia1ty items coated by the many industrial categories covered by these emission limits. Some low-polluting coatings are beinq used on production lineswhile others are in various stages of research. There wi11 

### be, however, situtationswhere low-polluting coatingsmay never be applicable and even the use of add-on control technology may not be feasible eitlher technically or economically.Manufacture of Metal Parts and Products 

# P

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 miscellaneousmetal 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 

### II I Surface 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 1iter 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 mi1s 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 solvent techno1ogy as compared to conventional high organic sol vent coatings

# . 5.1 WATER-BORNE (SPRAY, DIP, OR FLOW COAT) There are several advantages to converting towater-borne coatings. " Conversion towater-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 towater-borne coatings provides a potential decrease intoxicity and flammability. " Water-borne coatings may be thinned with water. " Coating equipment can be cleaned or flushed with water rather than organic solvent. (Ifwater-borne coatings are allowed todry, however, they are then no longer soluble inwater and must be cleaned with solvent. " Use of water-borne coatings may allow a decrease inoven temperature. " Use of water-borne coatings will permit some reduction inair flow since the amount of organics which must be evaporated inthe oven is 1 reduced. (The permissible reduction may be 1imi ted, however, by high humidity within the oven which will result incondensation on the oven walls and possibly
cause improper curing of the film. Insome cases the dry-off oven may no longer be necessary. 2 There are some potential disadvantages towater-borne coatings when compared with conventional organic-borne coatings.Spraying with water-borne coatings may require closer attention to detail than with organic-bornecoatings because temperature, humidity, gun-to-metal-part distance, and flashoff timemay 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 equipmentmay have to be replaced or adjusted (due to different surface tension of water than thatof 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 electrodeposition. Themajor 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 

### 1iquid 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 electrical process, for good paint circulation in the bath, and to operate the ultrafilter. Electrodepositionmay 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 coatingswill not hide imperfections in the substrate. Conversion to electrodepositionwill 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 ameans of reducing emissions of VOC is that theymay 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 spraybooth 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 influencedby the organic concentration 1

### imitations imposed for safety reasons)8, the use of higher solids coatingswill reduce energy requirements. Solid and liquid wastes may also decrease since less coating is applied per dry mil. However, the tackiness of high solid coatingsmay make cleanupmore difficult.9 

### Some two-component high solids coatingsmay 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 completelyeliminated. 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 application of solvent-borne coatingsmay not be required. Energy requirements for the ovensmay 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 requirementswill resultwhen a conventional single coat spray application is replaced with powder and 55-70 percent reduction wi11 occur for a two-coat spray application.)10 

### The exhaust air from the spraybooth can be filtered and returned to theworking 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 ofpowder finesmay have to be discarded, and the larger and heavier granulesmay 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 application equipment, spraybooths, and associated equipment (and often ovens) used for liquid systemsmust be replaced. Thiswill then limit the flexibility of 

### the faci1

### 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 metal1ics. 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 coatingsmust be kept dry since their subsequent performance 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. Thismay greatly curtail production capacities. Color changesmay 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 miscellaneousmetal 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 concentrationof 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 adsorberwith an attendant reduction in energy requirements.

### The amount of solid and liquid waste generated by theuse of a carbon adsorberwill 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 spraybooths, however, may require pretreatment by fi1

### tration or scrubbing since the overspraymay foul the adswber bed. Water miscible solvents may produce awater pollution problem if the adsorber is regeneratedwith steam. This, however, can be avoided by incinerating the regeneration stream, by stripping the organics from the condensate or using nitrogen gas as a strippingmedium. 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 miscel1

### aneousmetal part and product industries, any recovery or solvents would be for fuel value only. An important factorwhen considering instal1

### ation 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 Themost common and widely applicable technique for the reduction of organic emissions is incineration. Incinerators (or afterburners) have been used formany 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 temperaturewill 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 areaswhere secondary heat may be utilized, an incineration systemmay even reduce the plant's overall fuel consumption. Table 5-1 shows the potentia1 decreases in energy usage when using incinerators followed 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 inTable 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 BTUIHR a,b,13

NON-CATALYTIC INCINERATORS 5 percent LEL 1 5 percent LEL No Heat Recovery 5000 scfm 15,000 scfm 30,000 scfm 38%EfficientPrimary 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% Efficientprimary 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 inlettemperature 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/HRa,b,c,l4

85% EFFICIENCY PRIMARY HEAT RECOVERY 5 percent LEL 15percent 

### 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 theheat of combustion of the VOC. b, Energy value of VOC used is 1.2 MM/BTU/HR per 10,000 scfm. (-) indicates overall fuel savings5.7 REFERENCES McCormick, Donald, "Converting a Flowcoater to Water-Borne Paint," Whirlpool Corporation. Presented atthe 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. Cit. McCorrnick, Op. Cit. Products Finishing, Op. Ci t. Kennedy, W. D., "Major Appliance Electrocoat," Whirl pool Corporation. Presented at the NPCA Chmical Coatinas Conference, Cincinnati, Ohio,
u April 22, 1976. DeVittorio, J. M. 

### , Ransburg Corporation, "Application Equipment for High-Solids and Plural Component Coatings," Volume I, No. 2, April, 1976. "QuestionCorner," High-Solids Coatings, Volume I, No. 3, July, 1976. "Economic Justification of Powder Coating,

### " Powder Finishing World

### , pages 18-22, 4th Quarter, 1976. LeBras, Louis, Technical Director, PPG Industries, Inc.

### , Pittsburgh, Pennsylvania. Letter to V. N. Gallagher incomment of the metal furniture draft document. Letter dated August 31, 1977. Ibid. Combustion Engineering Air Prehater, We11 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 TECHNIQUESAND ENFORCEMENT ASPECTS This chapter discusses the recommended emission limits, themonitoring 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 ofmass or volume and may be based on the entire coating (includingorganic 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 (kgsper liter of coating or Ibs per gallon of coating

# - minus water) as it is delivered to the coating applicator. Thewater 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 onewith one pound per gallon. The disadvantageof this format, however, is that the analytical methods aremore 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-DutyTrucks," 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 interms 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 inAppendix 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 isnot 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 unpigmented 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 inorganic solvent. They do not consider the reduction inVOC emissions which would result from a decrease infilmthickness or an increase inthe transfer efficiency of a coating. For example, assume a facility applying conventional coating at 1.2 mils filmthickness, converts to a coating which, although it contains less organic solvent, does not quite meet the recommended emission limit. If the new coating isserviceable when applied ina thinner coat, it may result ina reduction inVOC emissions comparable toor 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 facilitythat 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 faci1i

### 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 themass 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 evenmore 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 compliancemethod, the air pollution control agency should require that the coating lines be equipped with an approved capture device to assure effective containment. The capture systemwill 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 recognizedthatsome coatingswill emit more 

### VOC thanmerely 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 f

### ram 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. Themore 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 atlow 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 verificationofthe efficiency of the device should be sufficient to
assure compliancewith 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 amiscellaneous metal part or product facilitywill meet a 

### recommended emission limit. It also explainshow 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 substratewith a film that provides both corrosion resistance to the substrate and esthetic appeal. Therefore, the rational basis for specifying an a1lowable VOC emission limit would be in units of coating volume (e.g., grams of 

### VOC per squaremeter (lbs/sq. ft)per unit thickness of film). However, the complexity of any analytical method which would provide ameasurement of the volume of a cured coating precludes this approach. As a compromise, the limitationswere 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 solventdensity) 

# ,, 1- 

### volume fract~on of water

The following examples show the use of these equations to determine the emission factor for both organic solvent-borneand 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-bornecoating 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), this coating is in compliance.

CASE 2: 

### Determine the emission factor for awater-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 respectivevolumes 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 installed. However, this method of determining the equivalent emission limit factor is not as straightforward as the previous two cases and must also consider the volume of solids in the coating.

CASE 3: 

### Determine the emission factor for a conventional organic-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-solventcoating 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 = (~)(0.88 kglliter) 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 

### 1imit 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 amaterialbalance 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 ProtectionAgency, memorandum concerning requirements for ventilation of spray booths and ovens. Dated March 10, 1977.I TECHNICAL REPORTDATA (PleasereadIurtlztctlonsonthereverse beforecompleting) 1. REPORT NO. 2. (3.RECIPIENT'S ACCESSIOWNO. 

### I

- Control of Volatile Organic Emissions from Stationary Sources 

## - Volume VI: Surface Miscellaneous Metal Parts and Products 8.PERFORMINGORGANIZATIONREPORT NO 

# I Vera Gallagher, John Pratapas 

# I OAQPS No. 1.2-101
NAMEANDADDRESS 10. PROGRAM ELEMENTNO. U.S. Environmental ProtectionAgency office of Air and Waste 

## ana age ment 11.CONTRACTIGRANTNO. Office ofAirQualityPlanning and Standards Research Triangle Park, North Carolina 27711 NAMEANDADDRESS
14.SPONSORING AGENCY CODE 

# I

15.SUPPLEMENTARY NOTES

16.ABSTRACT This document provides the necessary guidance for development of regulations to limitemissions of volatileorganic compounds (VOC) from the coating operations of m iscellaneous metal parts and products. This guidance i, ncludes emission 1 imitswhich represent Reasonably Avai1 able Control Technology (RACT) forthe miscellaneous metal part and product industries, describes the industries, shows the methods by which VOC emissions can be reduced inthese industries and describes the monitoring and enforcement aspects.

KEYWORDSANDDOCUMENTANALYSIS DESCRIPTORS ~.IDENTIFIERS/OPENENDEDTERMS c. coSATlField/Gro~p AirPollution AirPollution Control Miscellaneous Metal Part and Product Stationary Sources Industries VolatileOrganic Compound Emission Organic Vapors L im it:s Regulatory Guidance 

# I I I

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