EPA-450/3-78-006
April 1978
STUDY TO SUPPORT
NEW SOURCE PERFORMANCE
STANDARDS FOR SURFACE
COATING OF METAL
FURNITURE
U.S. ENVIRONMENTAL PROTECTION AGENCY
Office of Air and Waste Management
Office of Air Quality Planning and Standards
Research Triangle Park, North Carolina 27711
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EPA-450/3-78-006
STUDY TO SUPPORT
NEW SOURCE PERFORMANCE
STANDARDS FOR SURFACE COATING
OF METAL FURNITURE
by
Springborn Laboratories, Inc.
Enfield, Connecticut 06082
Contract No. 68-02-2075
EPA Project Officer: Vera N. Gallagher
Prepared for
U.S. ENVIRONMENTAL PROTECTION AGENCY
Office of Air and Waste Management
Office of Air Quality Planning and Standards
Research Triangle Park, North Carolina 27711
April 1978
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This report is issued by the Environmental Protection Agency to report
technical data of interest to a limited number of readers. Copies are
available free of charge to Federal employees, current contractors and
grantees, and nonprofit organizations - in limited quantities - from the
Library Services Office (MD-35), U.S. Environmental Protection Agency,
Research Triangle Park, North Carolina 27711; or, for a fee, from the
National Technical Information Service, 5285 Port Royal Road, Springfield,
Virginia 22161.
This report was furnished to the Environmental Protection Agency by
Springborn Laboratories, Inc. , Enfield, Connecticut, in fulfillment
of Contract No. 68-02-2075. The contents of this report are reproduced
herein as received from Springborn Laboratories, Inc. The opinions,
findings, and conclusions expressed are those of the author and not
necessarily those of the Environmental Protection Agency. Mention of
company or product names is not to be considered as an endorsement
by the Environmental Protection Agency.
Publication No. EPA-450/3-78-006
11
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CONTENTS
2. INTRODUCTION 2-1
2.1. AUTHORITY FOR THE STANDARDS 2-1
2.2. SELECTION OF CATEGORIES OF STATIONARY SOURCES .... 2-4
2.3. PROCEDURE FOR DEVELOPMENT OF STANDARDS
PERFORMANCE 2-6
2.4. CONSIDERATION OF COSTS 2-8
2.5. CONSIDERATION OF ENVIRONMENTAL IMPACTS 2-9
2.6. IMPACT ON EXISTING SOURCES 2-10
3. THE METAL FURNITURE INDUSTRY 3-1
3.1. GENERAL DESCRIPTION 3-1
3.2. PROCESSES OR FACILITIES AND THEIR EMISSIONS 3-5
3.2.1. The Basic Processes 3-5
3.2.1.1. Spray Coating 3-5
3.2.1.2. Dip Coating 3-10
3.2.1.3. Flow Coating 3-13
3.2.2. Equipment Characteristics 3-14
3.2.3. Emission Characteristics 3-15
3.2.4. Parameters Affecting Emissions 3-17
3.3. REFERENCES 3-19
4. EMISSION CONTROL TECHNIQUES 4-1
4.1. THE ALTERNATIVE EMISSION CONTROL TECHNIQUES 4-1
4.1.1. Powder Coating 4-1
4.1.1.1. Electrostatic Spray 4-3
4.1.1.2. Fluidized Bed 4-12
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CONTENTS (Continued - 2)
4.1.2. Water-Borne Coatings 4-14
4.1.2.1. Electrodeposition 4-15
4.1.2.2. Water-Borne Spray 4-22
4.1.2.3. Water-Borne Dip 4-24
4.1.2.4. Water-Borne Flow Coating 4-24
4.1.3. Higher Solids Coating 4-25
4.1.4. Carbon Adsorption 4-27
4.1.5. Incineration 4-34
4.1.5.1. Thermal Incinerators 4-34
4.1.5.2. Catalytic Incineration 4-39
4.2. EMISSION REDUCTION PERFORMANCE OF CONTROL
TECHNIQUES 4-42
4.2.1. Powder Coating - Electrostatic Spray 4-43
4.2.2. Powder Coating - Fluidized Bed 4-43
4.2.3. Electrodeposition of Water-Bornes 4-43
4.2.4. Water-Borne Spray 4-44
4.2.5. Water-Borne Dip and Flow Coatings 4-46
4.2.6. Higher Solids Coatings 4-47
4.2.7. Incineration 4-49
4.2.8. Carbon Adsorption 4-49
4.3. REFERENCES 4-50
5. MODIFICATION AND RECONSTRUCTION 5-1
5.1. POTENTIAL MODIFICATIONS 5-2
5.2. RECONSTRUCTION 5-5
5.3. CONSTRAINTS 5-5
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CONTENTS (Continued -3)
5.4. REFERENCES 5-7
6. EMISSION CONTROL SYSTEMS 6-1
6.1. ALTERNATIVE A-2 6-4
6.2. ALTERNATIVE A-3 6-4
6.3. ALTERNATIVE A-4 6-4
6.4. ALTERNATIVE A-5 6-7
6.5. ALTERNATIVE B-2 6-7
6.6. ALTERNATIVE B-3 • 6-11
6.7. ALTERNATIVE B-4 6-11
6.8. ALTERNATIVE B-5 6-11
6.9. ALTERNATIVE B-6 6-11
6.10. REFERENCES 6-14
7. ENVIRONMENTAL IMPACT 7-1
7.1. AIR POLLUTION IMPACT 7-1
7.1.1. State Regulations and Controlled Emissions 7-3
7.1.2. Uncontrolled and Controlled Emissions (Alternatives) 7-5
7.1.2.1. Spray Coating 7-5
7.1.2.2. Dip Coating 7-6
7.1.2.3. Estimated Hydrocarbon Emission Reduction in Future Years .... 7-10
7.2. WATER POLLUTION IMPACT 7-17
7.3. SOLID WASTE DISPOSAL IMPACT 7-18
7.4. ENERGY IMPACT 7-20
7.5. OTHER ENVIRONMENTAL IMPACTS 7-23
7.6. OTHER ENVIRONMENTAL CONCERNS 7-23
7.6.1. Irreversible and Irretrievable Commitment of Resources 7-23
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CONTENTS (Continued -4)
Page
7.6.2. Environmental Impact of Delayed Standards 7-23
7.6.3. Environmental Impact of No Standards 7-24
7.7. REFERENCES 7-25
8. ECONOMIC IMPACT 8-1
8.1. INDUSTRY ECONOMIC PROFILE 8-1
8.1.1. Introduction 8-1
8.1.2. Industry Size 8-1
8.1.3. Industry Growth: Past and Projected 8-7
8.1.4. Industry Structure 8-12
8.1.5. Channels of Distribution 8-16
8.1.6. Industry Markets 8-17
8.1.7. Labor and Materials Costs 8-17
8.1.8. Financial Performance 8-21
8.1.9. Imports and Exports 8-21
8.1.10. Geographic Distribution 8-24
8.2. COST ANALYSIS OF ALTERNATIVE EMISSION CONTROL
SYSTEMS 8-27
8.2.1. Cost Effectiveness Summarized - New Facilities 8-29
8.2.2. Reconstructed Facilities 8-35
8.2.3. Water Pollution and Solid Waste Disposal 8-38
8.3. REFERENCES 8-39
9. RATIONALE FOR THE PROPOSED STANDARDS 9-1
9.1. SELECTION OF SOURCE FOR CONTROL 9-1
9.2. SELECTION OF POLLUTANTS AND AFFECTED FACILITIES .... 9-2
9.3. SELECTION OF THE BEST SYSTEM OF EMISSION
REDUCTION CONSIDERING COSTS 9-9
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CONTENTS (Continued 5)
9.4. SELECTION OF THE FORMAT OF THE PROPOSED
STANDARD 9-10
9.4.1. Concentration - Airborne Emissions 9-10
9.4.2. Mass/Time - Airborne Emissions 9-10
9.4.3. Equipment Standard - Airborne Emissions 9-11
9.4.4. Mass of Emissions/Unit of Coating Material Consumed 9-11
9.5. SELECTION OF EMISSION LIMITS
(To be prepared by EPA)
9.6. VISIBLE EMISSION STANDARDS
(To be prepared by EPA)
9.7. MODIFICATION/RECONSTRUCTION CONSIDERATION 9-14
9.7.1. Potential Modifications 9-15
9.7.2. Substitution of Equipment 9-17
9.7.3. Reconstruction 9-18
9.7.4. Constraints 9-18
9.8. SELECTION OF MONITORING REQUIREMENTS
(To be prepared by EPA)
9.9. SELECTION OF PERFORMANCE TEST METHODS
(To be prepared by EPA)
APPENDIX A. - EVOLUTION OF PROPOSED STANDARDS A-l
APPENDIX B. - INDEX TO ENVIRONMENTAL IMPACT CONSIDERATIONS B-l
Listing of Tables and Figures follows.
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LIST OF TABLES AND FIGURES
TABLES
3-2. Metal Furniture Trends and Projections in Thousand Dollars 3-3
at Constant Price (1972)
3-3. Metal Furniture Establishments 3-4
3-4. Material Balance Metal Furniture Electrostatic Spray Coating 3-8
3-5. Energy Balance Metal Furniture Coating Process 3-10
3-6. Material Balance Metal Furniture Dip Coating 3-11
3-7. Energy Balance Dip Coating Metal Furniture 3-13
3-8. Average Emissions for the Metal Furniture Finishing Process 3-16
Liters of Solvent Per 1000 Square Meters (Gallons of Solvent
Per Square Foot)
4-1. Examples of Metal Furniture Finishing with Powder Coatings 4-5
4-2. Overall Weight Percent of Powder Utilized 4-9
4-3. Water-Borne Coatings 4-16
4-4. Electrodeposition in the Metal Furniture Industry 4-17
4-5. Problem Solvents for Carbon Adsorption 4-30
4-6. Percent Emission Reduction for Water-Borne Coatings Applied 4-45
by Spray Techniques
4-7. Reduction of Organic Solvent Emissions 4-46
92,400 Square Meters (1,000,000 Square Feet) Sprayed at 65
Percent Efficiency Approximately 30 Percent Volume Solids
4-8. Percent Emission Reduction for Water-Borne Coatings Applied 4-47
by Dip and Flow Coating
6-1. Metal Furniture Emission Control Systems 6-2
Size of Line: 3,000,000 Square Feet Coated Area Per Year
6-2. Metal Furniture Emission Control Systems 6-3
Size of Line: 22,464,000 Square Feet Coated Area Per Year
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LIST OF TABLES AND FIGURES (Continued -2)
TABLES Page
7-1. Metal Furniture Painting Operation Spray Coating Hydrocarbon 7-7
Emission Factors and Controlled and Uncontrolled Model Plants
7-2. Metal Furniture Painting Operation Dip Coating Hydrocarbon 7-9
Emission Factors and Control Efficiency Controlled and Un-
controlled Model Plants
7-3. Comparative Effectiveness of Alternate Control Systems 7-11
Expressed in Annual Organic Emissions Controls on a Spray
Coating Operation Assumed Annual Penetration: 5 Percent
7-4. Comparative Effectiveness of Alternate Control Systems 7-12
Expressed in Annual Organic Emissions Controls on a Dip
Coating Operation Assumed Annual Penetration: 5 Percent
7-5. Comparative Effectiveness of Alternate Control Systems 7-13
Expressed in Annual Organic Emission Controls on a Spray
Coating Operation Assumed Annual Penetration: 10 Percent
7-6. Comparative Effectiveness of Alternate Control Systems 7-14
Expressed in Annual Organic Emissions Controls on a Dip
Coating Operation Assumed Annual Penetration: 10 Percent
7-7. Effectiveness of Alternate Control Systems - Year 1985 7-15
Expressed in Annual Organic Emissions Controls on a Dip
Coating Operation Comparative Annual Penetration:
5 and 10 Percent
7-8. Effectiveness of Alternative Control Systems - Year 1985 7-16
Expressed in Annual Organic Emission Controls on a Spray
Coating Operation Comparative Annual Penetration:
5 and 10 Percent
7-9. Energy Balance - On a Spray Coating Operation 7-21
7-10. Energy Balance on a Dip Coating Operation 7-22
8.1-1. Basic Industry Statistics Metal Household Furniture (SIC 2514) 8-2
8.1-2. Basic Industry Statistics Metal Office Furniture (SIC 2522) 8-3
8.1-3. Basic Industry Statistics Public Building and Related 8-4
Furniture (SIC 2531)
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LIST OF TABLES AND FIGURES (Continued -3)
TABLES Page
8.1-4. Basic Industry Statistics Metal Partitions and Fixtures (SIC 2542) 8-5
8.1-5. Basic Industry Statistics Metal Furniture Industry (Total Figures 8-6
for SIC 2514, 2522, 2531, 2542)
8.1-6. Value of Metal Furniture Industry Shipments in Current and 8-8
Constant Dollars, 1967, 1975
8.1-7. Concentration Ratios in Metal Furniture Manufacturing 8-13
8.1-8. Percent of Value Added in Metal Furniture Manufacturing by 8-14
Multiunit and Single Unit Companies, 1972
8.1-9. Distribution by Firm Size in the Metal Furniture Industry of 8-15
Establishments, Production Workers and Value Added by Manu-
facture, 1972 (Share of Total, Percent)
8-1-10. Metal Furniture Product Mix, 1963 - 1975 8-18
(As Percent of Value of Total Industry Shipments)
8.1-11. Labor and Materials Costs in Metal Furniture Manufacturing 8-19
Relative to Value of Industry Shipments
8.1-12. Trends in Wages and Productivity in the Metal Furniture 8-20
Industry 1958 - 1975
8.1-13. Metal Furniture Coating Materials Cost vs. Total Materials Cost 8-22
and Value of Shipments, 1972 and 1967
8.1-14. Financial Ratios for Selected Metal Furniture Manufacturers 8-23
8.1-15. Geographical Distribution of Establishements and Value Added by 8-25
Manufacture, Metal Furniture Industry, 1972
8.1-16. Geographical Distribution of Metal Furniture Industry Establish- 8-26
ments, 1972 (In Percent of Number of Establishments)
8.2-1. Case Codes A-l - A-7 8-28
8.2-2. Case Codes B-l - B-6 8-29
8.2-3. Alternative Cases - New Facilities Metal Furniture - Part I 8-31
8.2-4. Alternative Cases - New Facilities Metal Furniture - Part II 8-32
8.2-5. Metal Furniture Coating Solvent Emissions from Affected Facilities 8-34
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LIST OF TABLES AND FIGURES (Continued 4)
TABLES Page
8.2-6. Codes A.l-1 - A.l-3 8-35
8.2-7. Codes B.l-1 - B.l-3 8-35
8.2-8. Alternative Cases - Reconstructed Facilities Metal Furniture 8-36
Parti
8.2-9. Alternative Cases - Reconstructed Facilities Metal Furniture 8-37
Part II
FIGURES
3-1. Electrostatic Solvent Spray Costing System 3-6
3-2. Flow Diagram - Material for Electrostatic Spray Solvent- 3-9
Borne Coating
3-3. Flow Diagram - Material for Solvent-Borne Dip Coating 3-12
4-1. Schematic of Electrostatic Powder Spray Process 4-4
4-2. Sophisticated Recovery System 4-8
4-3. Schematic of Fluidized Bed Apparatus 4-13
4-4. Typical Electrodeposition System Diagram 4-19
4-5. Diagram of an Activated-Carbon Adsorber System 4-28
4-6. Effluent Concentration Curve of Butane Vapor From an Activated 4-32
Carbon Bed as Function of Time
4-7. Forced-Draft System Eliminating Solvent Vapors from Surface 4-35
Coating Process
4-8. Coupled Effects of Temperature and Time on Rate of 4-38
Pollutant Oxidation
4-9. Schematic Diagram of Catalytic Afterburner Using Torch-Type Pre- 4-40
heat Burner with Flow of Preheat Waste Stream Through Fan to
Promote Mixing
4-10. Effect of Temperature on Oxidative Conversion of Organic Vapors 4-41
in a Catalytic Incinerator
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LIST OF TABLES AND FIGURES (Continued -5)
FIGURES
4-11. Emission Reduction Potential (Percent) With Use of Higher Solids 4-48
Coatings in Place of 28 Volume Percent Solvent-Borne Paint
(50 Percent Deposition Efficiency)
6-1. Flow Diagram - Alternative A-2 Application of Solvent-Borne 6-5
Coating by Electrostatic Spray Base Case with Incinerator on Oven
6-2. Flow Diagram - Alternative A-3 Application of Solvent-Borne 6-6
Coating by Electrostatic Spray Base Case with Carbon Adsorber
on Spray Booth
6-3. Flow Diagram - Base Case Alternatives A-4 and A-6 Application of 6-8
Coating by Electrostatic Spray Conventional (Base Case), or High
Solids (A-4) Solvent-Borne Coatings or Water-Borne Coatings (A-6)
6-4. Flow Diagram - Alternative A-5 Application of Powder Coating 6-9
Electrostatic Spray
6.5. Flow Diagram - Alternative B-2 Application of Water-Borne Coating 6-10
by Electrodeposition (EDP)
6-6. Flow Diagram - Alternative B-3 Application of Solvent-Borne Dip 6-12
Coating Base Case with Carbon Adsorber on Dip Tank
6-7. Flow Diagram - Alternative B-4 Application of Solvent-Borne Dip 6-13
Coating Base Case with Incinerator on Oven
8.1-1. Real Gross National Product and Metal Furniture Industry Shipments 8-9
in Constant Dollars, 1967 - 1975
8.1-2. Percent Change From Previous Year in Real Gross National Product 8-10
and Constant Dollar Metal Furniture Industry Shipments
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2. INTRODUCTION
Standards of performance are proposed following a detailed investigation of air
pollution control methods available to the affected industry and the impact of their
costs on the industry. This document summarizes the information obtained from such
a study. Its purpose is to explain in detail the background and basis of the proposed
standards and to facilitate analysis of the proposed standards by interested persons,
including those who may not be familiar with the many technical aspects of the
industry. To obtain additional copies of this document or the Federal Register notice
of proposed standards, write to EPA Library (MD-35), Research Triangle Park, North
Carolina, 27711. Specify Standards Support and Environmental Impact Statement,
Volume 1: Proposed Standards of Performance for Surface Coating of Metal
Furniture, document number EPA 450/3-78-006 when ordering.
2.1. AUTHORITY FOR THE STANDARDS
Standards of performance for new stationary sources are established under
Section 111 of the Clean Air Act (42 U.S.C. 7411), as amended, hereafter referred to
as the Act. Section 111 directs the Administrator to establish standards of
performance for any category of new stationary source of air pollution which "...
causes or contributes significantly to, air pollution which may reasonably be
anticipated to endanger public health or welfare."
The Act requires that standards of performance for stationary sources reflect,
"... the degree of emission limitation achievable through the application of the best
technological system of continuous emission reduction . . . the Administrator
determines has been adequately demonstrated." In addition, for stationary sources
whose emissions result from fossil fuel combustion, the standard must also include a
percentage reduction in emissions. The Act also provides that the cost of achieving
the necessary emission reduction, the non-air quality health and environmental
impacts and the energy requirements all be taken into account in establishing
standards of performance. The standards apply only to stationary sources, the
construction or modification of which commences after regulations are proposed by
publication in the Federal Register.
The 1977 amendments to the Act altered or added numerous provisions which
apply to the process of establishing standards of performance.
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1. EPA is required to list the categories of major stationary sources which
have not already been listed and regulated under standards of performance.
Regulations must be promulgated for these new categories on the following schedule:
25 percent of the listed categories by August 7, 1980
75 percent of the listed categories by August 7, 1981
100 percent of the listed categories by August 7, 1982
A governor of a state may apply to the Administrator to add a category which is not
on the list or to revise a standard of performance.
2. EPA is required to review the standards of performance every four years,
and if appropriate, revise them.
3. EPA is authorized to promulgate a design, equipment, work practice, or
operational standard when an emission standard is not feasible.
4. The term "standards of performance" is redefined and a new term
"technological system of continuous emission reduction" is defined. The new
definitions clarify that the control system must be continuous and may include a low-
polluting or non-polluting process or operation.
5. The time between the proposal and promulgation of a standard under
Section 111 of the Act is extended to six months.
Standards of performance, by themselves, do not guarantee protection of
health or welfare because they are not designed to achieve any specific air quality
levels. Rather, they are designed to reflect the degree of emission limitation
achievable through application of the best adequately demonstrated technological
system of continuous emission reduction, taking into consideration the cost of
achieving such emission reduction, any non-air quality health and environmental
impact and energy requirements.
Congress had several reasons for including these requirements. First,
standards with a degree of uniformity are needed to avoid situations where some
states may attract industries by relaxing standards relative to other states. Second,
stringent standards enhance the potential for long-term growth. Third, stringent
standards may help achieve long-term cost savings by avoiding the need for more
expensive retrofitting when pollution ceilings may be reduced in the future. Fourth,
certain types of standards for coal burning sources can adversely affect the coal
market by driving up the price of low-sulfur coal or effectively excluding certain
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coals from the reserve base because their untreated pollution potentials are high.
Congress does not intend that new source performance standards contribute to these
problems. Fifth, the standard-setting process should create incentives for improved
technology.
Promulgation of standards of performance does not prevent state or local
agencies from adopting more stringent emission limitations for the same sources.
States are free under Section 116 of the Act to establish even more stringent
emission limits than those established under Section 111 or those necessary to attain
or maintain the National Ambient Air Quality Standards (NAAQS) under Section 110.
Thus, new sources may in some cases be subject to limitations more stringent than
standards of performance under Section 111, and prospective owners and operators of
new sources should be aware of this possibility in planning for such facilities.
A similar situation may arise when a major emitting facility is to be
constructed in a geographic area which falls under the prevention of significant
deterioration of air quality provisions of Part C of the Act. These provisions require,
among other things, that major emitting facilities to be constructed in such areas are
to be subject to best available control technology. The term "Best Available Control
Technology" (BACT), as defined in the Act, means "... an emission limitation based
on the maximum degree of reduction of each pollutant subject to regulation under
this Act emitted from or which results from any major emitting facility, which the
permitting authority, on a case-by-case basis, taking into account energy, environ-
mental, and economic impacts and other costs, determines is achievable for such
facility through application of production processes and available methods, systems,
and techniques, including fuel cleaning or treatment or innovative fuel combustion
techniques for control of each such pollutant. In no event shall application of 'Best
Available Control Technology1 result in emissions of any pollutants which will exceed
the emissions allowed by any applicable standard established pursuant to Section 111
or 112 of this Act."
Although standards of performance are normally structured in terms of
numerical emission limits where feasible, alternative approaches are sometimes
necessary. In some cases physical measurement of emissions from a new source may
be impractical or exorbitantly expensive. Section lll(h) provides that the
Administrator may promulgate a design or equipment standard in those cases where it
is not feasible to prescribe or enforce a standard of performance. For example,
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emissions of hydrocarbons from storage vessels for petroleum liquids are greatest
during tank filling. The nature of the emissions, high concentrations for short periods
during filling, and low concentrations for longer periods during storage, and the
configuration of storage tanks make direct emission measurement impractical.
Therefore, a more practical approach to standards of performance for storage vessels
has been equipment specification.
In addition, Section lll(h) authorizes the Administrator to grant waivers of
compliance to permit a source to use innovative continuous emission control
technology. In order to grant the waiver, the Administrator must find: (1) a
substantial likelihood that the technology will produce greater emission reductions
than the standards require, or an equivalent reduction at lower economic, energy or
environmental cost; (2) the proposed system has not been adequately demonstrated;
(3) the technology will not cause or contribute to an unreasonable risk to public
health, welfare or safety; (4) the governor of the state where the source is located
consents; and that, (5) the waiver will not prevent the attainment or maintenance of
any ambient standard. A waiver may have conditions attached to assure the source
will not prevent attainment of any NAAQS. Any such condition will have the force of
a performance standard. Finally, waivers have definite end dates and may be
terminated earlier if the conditions are not met or if the system fails to perform as
expected. In such a case, the source may be given up to three years to meet the
standards, with a mandatory progress schedule.
2.2. SELECTION OF CATEGORIES OF STATIONARY SOURCES
Section 111 of the Act directs the Administrator to list categories of
stationary sources which have not been listed before. The Administrator, "... shall
include a category of sources in such list if in his judgement it causes, or contributes
significantly to, air pollution which may reasonably be anticipated to endanger public
health or welfare." Proposal and promulgation of standards of performance are to
follow while adhering to the schedule referred to earlier.
Since passage of the Clean Air Amendments of 1970, considerable attention
has been given to the development of a system for assigning priorities to various
source categories. The approach specifies areas of interest by considering the broad
strategy of the Agency for implementing the Clean Air Act. Often, these "areas" are
actually pollutants which are emitted by stationary sources. Source categories which
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emit these pollutants were then evaluated and ranked by a process involving such
factors as: (1) the level of emission control (if any) already required by state
regulations; (2) estimated levels of control that might be required from standards of
performance for the source category; (3) projections of growth and replacement of
existing facilities for the source category; and (4) the estimated incremental amount
of air pollution that could be prevented, in a pre-selected future year, by standards of
performance for the source category. Sources for which new source performance
standards were promulgated or are under development during 1977 or earlier, were
selected on these criteria.
The Act amendments of August 1977, establish specific criteria to be used in
determining priorities for all source categories not yet listed by EPA. These are: (1)
the quantity of air pollutant emissions which each such category will emit, or will be
designed to emit; (2) the extent to which each such pollutant may reasonably be
anticipated to endanger public health or welfare; and (3) the mobility and
competitive nature of each such category of sources and the consequent need for
nationally applicable new source standards of performance.
In some cases, it may not be feasible to immediately develop a standard for a
source category with a high priority. This might happen when a program of research
is needed to develop control techniques or because techniques for sampling and
measuring emissions may require refinement. In the developing of standards,
differences in the time required to complete the necessary investigation for different
source categories must also be considered. For example, substantially more time may
be necessary if numerous pollutants must be investigated from a single source
category. Further, even late in the development process the schedule for completion
of a standard may change. For example, inability to obtain emission data from well-
controlled sources in time to pursue the development process in a systematic fashion
may force a change in scheduling. Nevertheless, priority ranking is, and will continue
to be, used to establish the order in which projects are initiated and resources
assigned.
After the source category has been chosen, determining the types of facilities
within the source category to which the standard will apply must be decided. A
source category may have several facilities that cause air pollution and emissions
from some of these facilities may be insignificant or very expensive to control.
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Economic studies of the source category and of applicable control technology may
show that air pollution control is better served by applying standards to the more
severe pollution sources. For this reason, and because there is no adequately
demonstrated system for controlling emissions from certain facilities, standards often
do not apply to all facilities at a source. For the same reasons, the standards may not
apply to all air pollutants emitted. Thus, although a source category may be selected
to be covered by a standard of performance, not all pollutants or facilities within that
source category may be covered by the standards.
2.3. PROCEDURE FOR DEVELOPMENT OF STANDARDS PERFORMANCE
Standards of performance must: (1) realistically reflect the best demonstated
control practice; (2) adequately consider the cost, and the non-air quality health and
environmental impacts and energy requirements of such control; (3) be applicable to
existing sources that are modified or reconstructed as well as new installations; and
(4) meet these conditions for all variations of operating conditions being considered
anywhere in the country.
The objective of a program for development of standards is to identify the best
technological system of continuous emission reduction which has been adequately
demonstrated. The legislative history of Section 111 and various court decisions
make clear that the Administrator's judgement of what is adequately demonstrated is
not limited to systems that are in actual routine use. The search may include a
technical assessment of control systems which have been adequately demonstrated
but for which there is limited operational experience. In most cases, determination
of the "... degree of emission reduction achievable ..." is based on results of tests
of emissions from well controlled existing sources. At times, this has required the
investigation and measurement of emissions from control systems found in other
industrialized countries that have developed more effective systems of control than
those available in the United States.
Since the best demonstrated systems of emission reduction may not be in
widespread use, the data base upon which standards are developed may be somewhat
limited. Test data on existing well-controlled sources are obvious starting points in
developing emission limits for new sources. However, since the control of existing
sources generally represents retrofit technology or was originally designed to meet an
existing state or local regulation, new sources may be able to meet more stringent
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emission standards. Accordingly, other information must be considered before a
judgment can be made as to the level at which the emission standard should be set.
A process for the development of a standard has evolved which takes into
account the following considerations.
1. Emissions from existing well-controlled sources as measured.
2. Data on emissions from such sources are assessed with consideration of
such factors as: (a) how representative the tested source is in regard to feedstock,
operation, size, age, etc.; (b) age and maintenance of the control equipment tested;
(c) design uncertainties of control equipment being considered; and (d) the degree of
uncertainty that new sources will be able to achieve similar levels of control.
3. Information from pilot and prototype installations, guarantees by vendors
of control equipment, unconstructed but contracted projects, foreign technology, and
published literature are also considered during the standard development process.
This is especially important for sources where "emerging" technology appears to be a
significant alternative.
4. Where possible, standards are developed which permit the use of more
than one control technique or licensed process.
5. Where possible, standards are developed to encourage or permit the use of
process modifications or new processes as a method of control rather than "add-on"
systems of air pollution control.
6. In appropriate cases, standards are developed to permit the use of
stystems capable of controlling more than one pollutant. As an example, a scrubber
can remove both gaseous and particulate emissions, but an electrostatic precipitator
is specific to particulate matter.
7. Where appropriate, standards for visible emissions are developed in
conjunction with concentration/mass emission standards. The opacity standard is
established at a level that will require proper operation and maintenance of the
emission control system installed to meet the concentration/mass standard on a day-
to-day basis. In some cases, however, it is not possible to develop concentration/mass
standards, such as with fugitive sources of emissions. In these cases, only opacity
standards may be developed to limit emissions.
2-7
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2.4. CONSIDERATION OF COSTS
Section 317 of the Act requires, among other things, an economic impact
assessment with respect to any standard of performance established under Section
111 of the Act. The assessment is required to contain an analysis of:
1. the costs of compliance with the regulation and standard including the
extent to which the cost of compliance varies depending on the effective date of the
standard or regulation and the development of less expensive or more efficient
methods of compliance;
2. the potential inflationary recessionary effects of the standard or
regulation;
3. the effects on competition of the standard or regulation with respect to
small business;
4. the effects of the standard or regulation on consumer cost, and,
5. the effects of the standard or regulation on energy use.
Section 317 requires that the economic impact assessment be as extensive as
practical, taking into account the time and resources available to EPA.
The economic impact of a proposed standard upon an industry is usually
addressed both in absolute terms and by comparison with the control costs that would
be incurred as a result of compliance with typical existing state control regulations.
An incremental approach is taken since both new and existing plants would be
required to comply with state regulations in the absence of a federal standard of
performance. This approach requires a detailed analysis of the impact upon the
industry resulting from the cost differential that exists between a standard of
performance and the typical state standard.
The costs for control of air pollutants are not the only costs considered. Total
environmental costs for control of water pollutants as well as air pollutants are
analyzed wherever possible.
A thorough study of the profitability and price-setting mechanisms of the
industry is essential to the analysis so that an accurate estimate of potential adverse
economic impacts can be made. It is also essential to know the capital requirements
placed on plants in the absence of federal standards of performance so that the
additional capital requirements necessitated by these standards can be placed in the
2-8
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proper perspective. Finally, it is necessary to recognize any constraints on capital
availability within an industry, as this factor also influences the ability of new plants
to generate the capital required for installation of additional control equipment
needed to meet the standards of performance.
2.5. CONSIDERATION OF ENVIRONMENTAL IMPACTS
Section 102(2)(C) of the National Environmental Policy Act (NEPA) of 1969
required federal agencies to prepare detailed environmental impact statements on
proposals for legislation and other major federal actions significantly affecting the
quality of the human environment. The objective of NEPA is to build into the
decision-making process of federal agencies a careful consideration of all environ-
mental aspects of proposed actions.
In a number of legal challenges to standards of performance for various
industries, the Federal Courts of Appeals have held that environmental impact
statements need not be prepared by the Agency for proposed actions under Section 111
of the Clean Air Act. Essentially, the Federal Courts of Appeals have determined
that "... the best system of emission reduction, . . . require(s) the Administrator to
take into account counter-productive environmental effects of a proposed standard,
as well as economic costs to the industry . . ." On this basis, therefore, the Courts" .
. . established a narrow exemption from NEPA for EPA determination under Section
111."
In addition to these judicial determinations, the Energy Supply and Environ-
mental Coordination Act (ESECA) of 1974 (PL-93-319) specifically exempted
proposed actions under the Clean Air Act from NEPA requirements. According to
Section 7(c)(l), "No action taken under the Clean Air Act shall be deemed a major
federal action significantly affecting the quality fo the human environment within the
meaning of the National Environmental Policy Act of 1969."
The Agency has concluded, however, that the preparation of environmental
impact statements could have beneficial effects on certain regulatory actions.
Consequently, while not legally required to do so by Section 102(2)(C) of NEPA,
environmental impact statements will be prepared for various regulatory actions,
including standards of performance developed under Section 111 of the Act. This
voluntary preparation of environmental impact statements, however, in no way
legally subjects the Agency to NEPA requirements.
2-9
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To implement this policy, a separate section is included in this document which
is devoted solely to an analysis of the potential environmental impacts associated
with the proposed standards. Both adverse and beneficial impacts in such areas as air
and water pollution, increased solid waste disposal, and increased energy consumption
are identified and discussed.
2.6. IMPACT ON EXISTING SOURCES
Section 111 of the Act defines a new source as "... any stationary source, the
construction or modification of which is commenced . . ." after the proposed
standards are published. An existing source becomes a new source if the source is
modified or is reconstructed. Both modification and reconstruction are defined in
amendments to the general provisions of Subpart A of 40 CFR Part 60 which were
promulagated in the Federal Register on December 16, 1975 (40 FR 58416). Any
physical or operational change to an existing facility which results in an increase in
the emission rate of any pollutant for which a standard applies is considered a
modification. Reconstruction, on the other hand, means the replacement of
components of an existing facility to the extent that the fixed capital cost exceeds 50
percent of the cost of constructing a comparable entirely new source and that it be
technically and economically feasible to meet the applicable standards. In such
cases, reconstruction is equivalent to new construction.
Promulgation of a standard of performance requires states to establish
standards of performance for existing sources in the same industry under Section
lll(d) of the Act if the standard for new sources limits emissions of a designated
pollutant (i.e., a pollutant for which air quality criteria have not been issued under
Section 108 or which has not been listed as a hazardous pollutant under Section 112).
If a state does not act, EPA must establish such standards. General provisions
outlining procedures for control of existing sources under Section lll(d) were
promulgated on November 17, 1975, as Subpart B of 40 CFR Part 60 (40 FR 53340).
2.7 REVISON OF STANDARDS OF PERFORMANCE
Congress was aware that the level of air pollution control achievable by any
industry may improve with technological advances. Accordingly, Section 111 of the
Act provides that the Administrator "... shall, at least every four years, review and,
if appropriate, revise . . ." the standards. Revisions are made to assure that the
2-10
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standards continue to reflect the best systems that become available in the future.
Such revisions will not be retroactive but will apply to stationary sources constructed
or modified after the proposal of the revised standards.
2-11
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3. THE METAL FURNITURE INDUSTRY
3.1. GENERAL DESCRIPTION
In 1972 the metal furniture industry consisted of 1,588 companies which
employed 109,600 persons and sold $2.8 billions worth of metal furniture a year. As
compared with the levels in 1967 the number of companies decreased by 5 percent,
employment by 6 percent and shipments increased by 35 percent.
The metal furniture industry is highly fragmented, including the following
categories of products:
1. Household Metal Furniture SIC 2514
2. Office Metal Furniture SIC 2522
3. Public Building Furniture SIC 2531
4. Metal Partitions and Fixtures SIC 2542
The metal furniture industry consists of many small-scale companies employ-
ing less than 100 employees per company. During 1972, 85 percent of the metal
furniture manufacturing industry was represented by facilities with less than 100
employees and 37 percent of the industry involved manufacturing companies with less
than ten employees.
The employment data for the metal furniture industry is tablulated in Table 3-
1.
Table 3-1. EMPLOYMENT STATISTICS
(Number of Persons)
1972
Metal household 34,400
Metal office 27,600
Public building 21,400
Partitions and fixtures 26,200
Total 109,600
3-1
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The metal household furniture industry is comprised of companies manufactur-
ing metal furniture for kitchen, porch, lawn and outdoor usage and others including
metal bed frames, card tables and chairs. Of the 467 establishments manufacturing
metal household furniture 369 had less than 100 employees in 1972 .
The metal office industry is established from companies primarily involved in
manufacturing office chairs, desks, cabinets and cases and other metal office
furniture (including bookcases, storage cabinets, costumers, etc.). Of the 192
establishments manufacturing metal office furniture, 132 establishments had less
than 100 employees in 1972 .
Public building furniture may be metal or wood for schools, theaters, assembly
halls, churches and libraries. Companies manufacturing seats for automobiles and
aircraft are also included in this industry. Of the reported 422 companies
manufacturing public building furniture, 363 companies employ less than 100 persons
in 19721.
The industry of metal partitions and fixtures comprises establishments
primarily manufacturing metal shelving, storage racks, lockers, office and store
fixtures, prefabricated partitions and related fabricated products.
Of the 507 companies manufacturing metal partitions and fixtures 443
companies had less than 100 employees.
The metal furniture industry shipments value has shown an estimated 10
percent growth since 1972. The growth of the industry is mainly affected by the
growth in construction of houses, schools, hospitals, air terminals and office buildings.
The sales volume of metal furniture was estimated at 3.2 billion dollars, including
shipments of household furniture, office and building furniture and metal partitions
and fixtures in 1976. Table 3-2 shows sales of metal furniture by category.
The growth rates of each segment of the industry from 1972 to 1985 is based
on actual growth excluding inflation of the dollar. The household furniture industry
annual average growth rates are: 2.4 percent for 1973 to 1980 and 3.9 percent for
3
1980 to 1985 . The other segments of the furniture industry, excluding household
furniture, are showing the following annual growth rates: 4.4 percent for 1973 to
1980 and 3.0 percent for 1980 to 1985.
A geographical break-down of the metal furniture establishments is shown in
Table 3-3. The Middle Atlantic and East/North Central states accounted for almost
50 percent of all establishments.
3-2
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Table 3-2. METAL FURNITURE TRENDS AND PROJECTIONS
IN THOUSAND DOLLARS AT CONSTANT PRICE (1972)
1972a 19735 1974b 1975b 1976b 1980b 1985b
Household 890 911 933 956 979 1076 1303
Office 791 815 851 889 928 1102 1278
Public building 485 506 529 552 576 684 793
Partitions and fixtures 713 744 777 811 847 1006 1167
Total 2869 2976 3090 3208 3330 3868 4541
Sources: a 1972 Census of Manufacturers
BLS Review, November 1976, p 5
3-3
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Table 3-3. METAL FURNITURE ESTABLISHMENTS
Public Partitions
Household Office Buildingsa and Fixtures
New England 24 6 19 22
Maine — - 1
Massachusetts 17 3 — 12
Connecticut 5 - 5
Middle Atlantic 134 55 61 177
New York 90 31 24 113
New Jersey 15 7 11 29
Pennsylvania 29 17 26 35
East North Central 76 48 105 118
Ohio 12 11 31 32
Indiana 9 10 11 7
Illinois 43 11 27 42
Michigan 8 10 20 30
Wisconsin 4 6 16
West North Central 13 17 32 34
Minnesota 2 — 6 10
Iowa —2 8 —
Missouri 8 8 6 13
Kansas —2 86
Nebraska — — — 2
South Atlantic 75 14 48 35
Maryland 8
Delaware — 1
Virginia 62 91
North Carolina 16 3 16 5
Georgia 63 — 7
Florida 36 4 13 11
East South Central 33 9 36 21
Kentucky 73 — 3
Tennessee 10 2 17 8
Alabama 10 3 9 9
Mississippi 6 - 5 -
West South Central 25 8 45 28
Arkansas 3 - 17 2
Texas 17 5 22 20
Mountain Division 7 - 17 5
Utah - 3 -
Colorado 5 -
Pacific Division 80 34 59 67
Washington — ~ 10
California 77 32 43 63
United States Total 467 192 422 507
Source: The above data were compiled from information given in the 1972 Census
of Manufacturers, U. S. Department of Commerce.
aIncludes wood, metal and ,_,
plastic furniture
-------
3.2. PROCESSES OR FACILITIES AND THEIR EMISSIONS
3.2.1. The Basic Processes
The metal furniture coating industry includes all establishments which
manufacture metal furniture for office, public building and household use. Metal
furniture is usually made from low carbon steel sheet, strip or tubing.
Presently the metal furniture industry employs mostly solvent-borne coatings
for spray, dip coating and flow coating processes. Coating thickness ranges from 0.5
to 1.5 mils. Powder coating containing less than 5 percent volatiles is becoming more
acceptable for use on outdoor and institutional metal furniture. Coatings for metal
furniture must be resistant to abrasion scuffing and maintain good appearance.
Institutional furniture is subjected to a more abusive environment and in addition
must withstand regular cleaning with alkali type cleaners.
3.2.1.1. Spray Coating
Spray coating is generally applied by a combination of manual and automatic
spray. Semi-assembled furniture pieces are loaded onto an overhead conveyor moving
at a speed of 8i to 24 feet per minute. The plants usually operate on the basis of one
shift per day (8 hours) for 48 weeks per year .
Although finishing lines may vary from plant to plant, they have some common
characteristics which allow us to show the following major steps of such lines
employing organic solvent-borne paint systems.
Three-stage or five-stage washer
Oven
Manual touch-up spray
Electrostatic spray
Manual touch-up spray
Oven
The block diagram of these consecutive steps of the metal finishing process is
presented in Figure 3-1. Looking at each step of the operation we first examine the
washer. The pieces loaded on a conveyor go through a cleaning process which occurs
in the following sequence.
3-5
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Figure 3-1. ELECTROSTATIC SOLVENT SPRAY COATING SYSTEM
CA>
ck
\
^
f
j — j
i IA. \ ^T^ v-5 )
1 ' ' l
1 . 1 1
U A |_^| A A A
1 1 1 Y Y Y
ri,
U
(1) Conveyor
(2) Three-stage washer
(3) Oven
(4) Manual touchup spray
(5) Electrostatic booth
(6) Manual touchup spray
1
. . .-1
^ 1 /»
1
f
^
(6)
1
|
^.
c
^
^_
c +~
(__ »>
^
3
-^_
J
i i i i i
^
(2)
1 J ' ' '
_^
^•i
^ J
(7)
1 i 1
J 1 I
^
J
_/
Unload
(1)
Load
(7)
e oven
-------
1. Alkaline cleaner wash
2. Iron phosphate
3. Hot water rinse
4. Chromic wash
5. Cold water rinse
The alkaline cleaner washes the oil and grease and the phosphate treatment improves
the surface of the metal promoting adhesion of the coating.
After being washed and treated, the parts pass through a dry-off oven and then
into a touch-up booth, where manual air spray guns apply a reinforcement coating to
the intricate parts before the topcoat is applied. This step may be eliminated, its
inclusion depending on the configuration of the part being coated.
The topcoat operation is the most important step in the metal furniture
finishing process. This is usually applied by automatic or manual electrostatic
spraying technique. The paint is fed to the application equipment through a piping
system from the paint room. Average percent solids content in the paint is in the
range of 25 to 35 percent volume basis.
Because of the length of time that the item of furniture is in the spray booth
and flash off area, 70 to 90 percent of the solvent evaporates in the booth and flash-
off area .
Color change methods vary depending on the operation. In small manual spray
operations the operator purges the line with solvent, wipes the gun and connects the
line to the required color coating supply. On larger manual operations alternate spray
guns may be used each with different colors as required. Automated operations use
multiple spray guns programmed for color sequence as scheduled or in some cases the
line is purged with solvent and the guns are cleaned and set for the next scheduled
color. Some larger operations perform color mixing compounding with computer
programming to eliminate operator error. The color ingredients are selected in
accordance with computerized programs designed to meet customer requirements.
A material balance is shown in Table 3-4 which includes the discharge of
emissions at steps in the process. This data is based on a model coating line.
Discharge of solvents in the metal furniture finishing process occurs in the following
manner: 75 percent loss at the application and flash-off step and 25 percent loss in
the cure oven step of the operation. Figure 3-2 is a flow diagram showing process
steps of the topcoat operation.
3-7
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Table 3-4. MATERIAL BALANCE
METAL FURNITURE ELECTROSTATIC SPRAY COATING
Process Steps
Liters Per
278,000
Square Meters
Gallons Per
3,000,000
Square Feet
a
1. Coating applied
2. Material loss in the application
Solid
Solvent and trimmer
3. Total coating on furniture item
4. Oven evaporation loss - solvent discharge
5. Net dry solids on furniture item
31,226
8,250
3,825
15,223
20,297
5,074
7,104
1,010
4,023
5,363
1,341
1,876
a
3,000,000 square feet is the annual production figure based on the following:
(1) production rate - 1,562.5 square feet per hour
(2) time - 1 shift (8 hours per shift) per day; 240 days per year; 1,920 hours
per year (1,562.5 square feet per hour times 1,920 hours per year equals
3,000,000 square feet)
Application includes spray booth and flash-off area. Transfer efficiency of
electrostatic sprayed coating is 65 percent.
Water-wash spray booths capture solvents in the water curtain temporarily.
About 15 percent of the solvent is carried in the recirculated water and
eventually is discharged by evaporation into the venting system.
Coating at 35 percent solids - volume basis thickness 1 mil, dry.
3-8
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Figure 3-2. FLOW DIAGRAM - MATERIAL FOR ELECTROSTATIC
SPRAY SOLVENT-BORNE COATING
Stack
Stack
Stack
Load
CO
co
IT Evaporation T Evaporation
(Solvent) (Solvent)
Pretreat 3-Stage
Washer
-^
Pretreat Dry Off
Oven
-^
Solvent-Borne Coat
Spray Booth
-»»
Flash-Off
-^
Dry Off Oven
^- U
Unload
Paint Thinner
-n
Transfer Loss
(Solid)
-------
Energy requirements of the metal furniture coating operation are tabulated in
Table 3-5. This data is based on a model coating line.
Table 3-5. ENERGY BALANCE
METAL FURNITURE COATING PROCESS
Operation Steps 106 BTU Per Yeara
Application 590
Cure 3,905
Total 4,495
a Annual energy consumption calculations were based on 3,000,000 feet
produced per year, working from the following:
(1) production rate - 1,562.5 square feet per hour
(2) time - a shift (8 hours per shift) per day, 240 days per year; 1,920 hours
per year (1,562.5 square feet per hour times 1,920 hours per year equals
3,000,000 square feet)
3.2.1.2. Dip Coating
A metal furniture coating application was observed to utilize the dip coating
technique. The percent solids range for dip coating is estimated at 20 to 35 percent
volume basis. Dip coating may be done manually or automatically, depending on the
size of the parts to be coated. For large pieces of furniture dipping is done
manually .
For dip coating, the washing step may be eliminated. It is not unusual in some
dip operations for the paint to be contaminated by foreign material on the parts. The
conveyor is loaded with a number of parts (50 to 100) and lowered into a dipping
tank. After the parts are coated they pass over a drain board. Following a flash-off
period the coated parts are moved into an oven.
3-10
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A material balance is shown in Table 3-6 which includes the discharge of
emissions at steps in the process. Discharge of solvents in the coating application
occurs in the following manner: 40 to 70 percent loss at the application and flash-off
step and 30 to 60 percent loss in the cure oven step of the operation .
Figure 3-3 is a flow diagram showing process steps of the dip coating operation
based on a model coating line.
Process Steps
Table 3-6. MATERIAL BALANCE
METAL FURNITURE DIP COATING
Liters Per
2,086,957
Square Meters
168,356
a
Gallons Per
222.5 x 10.
Square Feet
44,480
5,893
65,658
96,805
43,774
53,032
1,557
17,347
25,576
11,565
14,011
1. Coating applied
2. Material loss in the application
Solid
Solvent discharge
3. Total coating on wet body
4. Oven evaporation loss-solvent discharge
5. Net dry solids on body
a 2,086,957 square meters is the annual production figure based on the following:
(1) production rate - 108.67 square meter per hour
(2) time - 1 shift (8 hours per shift) per day; 240 days per year; 1,920 hours per
year (109.67 square meters per hour times 1,920 hours per year equals 2,086,957
square meters per year
(3) based on 1 mil dry weight coating - 35 percent volume solids applied
Application includes spray booth and flash-off area. Transfer efficiency of dip
coating is 90 percent.
Energy requirements of the primer coat are tabulated in Table 3-7.
3-11
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Figure 3-3. FLOW DIAGRAM - MATERIAL FOR SOLVENT-BORNE DIP COATING
Load
Stack
Stack
4 Evaporation
(Solvent)
Pretreat 3-Stage
Washer
— ^
Pretreat Dry Off
Oven
— »•
Solvent-Borne Coat
Dipping Tank
— »•
f Evaporation
(Solvent)
Dry Off Oven
^ Unload
Paint, Thinner
T
-------
Table 3-7. ENERGY BALANCE
DIP COATING METAL FURNITURE
Operation Steps 106 BTU PER YEARa
Application 472
Cure 6,725
Total 7,197
a Annual energy consumption calculations were based on
2,086,957 square meters produced per year, working from
the following model line:
(1) production rate - 108.67 square meters per hour
(2) time - 1 shift (8 hours per shift) per day; 240 days
per year
(3) conversion factors 3412 BTU/KWH and 1000 BTU per
1 cubic foot of gas
3.2.1.3. Flow Coating
Some manufacturers may use flow coating for finishing metal furniture. The
flow coating method, in some of its aspects, resembles dipping, particularly since the
process requires liquid coating that will flow out easily. Viscosity of coating must be
closely controlled to provide satisfactory coverage without excessive runs or sags.
In flow coating parts are carried by a horizontal conveyor through a flow
coating chamber. The paint is directed against the parts from all angles through a
large number of nozzles. The excess coating drips off the lower edges of the parts
and leaves no strings and few, if any, congealed drops.
The simplest flow-coating equipment has paint nozzles over the work and on
all sides of the tunnel. Sometimes as many as 100 or more nozzles are used. The
flow coating method has less amount of solvent emitted than dip coating. Flow
coating is done in an enclosed booth, while evaporation takes place over the whole
surface of the dip tank.
3-13
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3.2.2. Equipment Characteristics
Equipment of the metal furniture finishing line associated with organic
emissions consists of the spraying booths, dip tanks, and ovens. Other equipment
involved in the metal furniture finishing operation includes the washer and the
conveyor for moving the parts to be painted through the process system.
The metal furniture coating is applied by either spraying, dipping or flow
coating methods.
Electrostatic spraying is probably one of the most widely used methods
because of its sharp reduction in the overspray.
Spray booth lengths vary for each facility because of the length of time that
the metal furniture item is in the spray booth. The majority of solvents are emitted
in the spraying area. An exhaust fan or blower is used to draw the contaminated air
out of the spray booths. To comply with OSHA regulations, a minimum air velocity
for exhaust devices is required to prevent personal breathing of excessive vapors and
paint particulates. The make-up air for the spray booth is usually kept at about
60°F and some relative humidity.
Water-washed spray booths are coming into use because of the increased effort
required to keep the spray booths clear of overspray particulate.
In a typical water-wash spray booth, the overspray paint particles are removed
by means of a curtain of water flowing down the side surfaces of the booth enclosure.
A dry-style spray booth uses a filter to remove the overspray paint particles
from the exhaust.
Bake oven temperatures range from 300 to 325 F. Solvent concentration in
the oven, usually measured as a percentage of the lower explosive limit (LEL) of
solvent in the air, is about 10 to 25 percent.
For some large parts and parts that do not need a perfect painting finish,
dipping and flow coating are the coating methods that will apply satisfactory coating
within a reasonable cost range. The dipping system consists of a tank to hold the
paint and a drain board to collect the dripped paint. Required air volume in the dip
tank area is less than that needed for spraying paint since there is less solvent lost in
transfer of the coating. Flow coating consists of a cabinet having nozzles on the top,
sides and bottom which directs the paint at the work from all angles. An improved
flow coating sytem eliminates all nozzles on top and sides of the cabinet and streams
of paint only from the bottom are directed against the work.
3-14
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3.2.3. Emission Characteristics
The two types of organic solvent-borne coatings used in the metal furniture
industry are enamels and lacquers.
"Enamel is a type of paint consisting of an intimate dispersion of pigments in a
varnish or resin vehicle. The vehicle may be an oil-resin mixture, or an entirely
synthetic resin. Those containing drying oils are converted to film by oxidation; those
comprised wholly of synthetic resins may be converted by either heat or oxygen or
both."8
Lacquers in contrast to enamels, do not undergo a chemical reaction when
exposed to heat. Applied lacquers are dried by evaporation of the solvent to form the
coating film.
The traditional coating materials used in the metal furniture coating industry
are organic solvent-borne compositions. Alkyd resins account for the largest portion
of all resins used in finishing metal furniture. Others include acrylics, amines, vinyls
and cellulosics. Some metallic coatings are used in finishing metal office furniture.
The solvents used in coatings for metal furniture are mixtures of aliphatics,
xylene, toluene and other aromatics, MEK and other solvents.
According to a recent survey by the National Paint and Coatings Association in
1975, the metal furniture and fixtures consumed 116 million pounds of solvents or 6
Q
percent of the total industrial coating solvent usage .
Based on our survey the average solvent emission for an electrostatic spray
operation was calculated to be 2.10 gallons per 1000 square feet. Assuming that a
metal furniture finishing line operates at a production rate of 1562.5 square feet an
hour for one shift (8 hours per day), this will mean that 12,500 square feet are
produced per day and that approximately 26.25 gallons of solvent are discharged daily
from the metal furniture spray coating operation. Loss from overspray was
o
calculated to be 15 kilograms per 1000 meters based on data collected from the
industry.
Average solvent emission for a dip coat operation was calculated to be 1.37
gallons per 1000 square feet. Assuming that a metal furniture dip line operates at a
production rate of 11,700 square feet per hour for eight hours per day, it will mean
that 93,000 square feet are produced per day and approximately 128 gallons of solvent
are discharged daily from the line.
3-15
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Calculations of solvent emissions from plants visited result in the following
emission factors for the spray and dip coat operations (Table 3-8).
Table 3-8. AVERAGE EMISSIONS FOR THE
METAL FURNITURE FINISHING PROCESS
Liters of Solvent Per 1000 Square Meters
(Gallons of Solvent Per Square Foot)
a b
Coatings Application Cure Total
Spray
Solvent-borne coat 64.50 21.50 86
(1.57) (0.53) (2.10)
Dip
Solvent-borne coat 31.35 25.65 57
(9.75) (9.62) (1.37)
a Application includes spray booth and flash-off area
Data presented as unconfirmed data reported from field surveys
Effluents from water wash in spray booths contain contaminants from
overspray of coatings. The water used in the spray booth curtain may be discharged
into a sludge tank where solids are removed and the water is recirculated. Immiscible
solvents captured by water curtains in spray booths evaporates from the water as it
recirculates and leaves at the booth vent. Solid waste discharge by the landfill
method may be the most appropriate for the metal furniture finishing operations.
3-16
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3.2.4. Parameters Affecting Emissions
Metal furniture industry solvent emissions are directly related to the types of
coating materials used. Naturally the greater the quantity of solvents in the coating
compositon the greater will be the air emissions. Lacquer having 15 to 17 volume
percent solids are higher in organic solvents than enamels which have 30 to 35 volume
percent solids. The usage of add-on equipment such as incinerators and carbon
adsorbers will also affect the solvent emissions. Springborn Laboratories' survey of
the metal furniture industry however, did not discover any add-on pollution control
equipment for treating solvent emissions.
The advance of powder coating materials in the metal furniture operations will
affect the emission discharge of the industry. Powder coating was found to be a
popular method in outdoor furniture and institutional furniture .
The advance of powder coating materials in the metal furniture industry has
been attributed to achieving better performance coating a slightly higher cost over
solvent-borne systems. Environmental improvement was an additional benefit.
Water-borne coatings have not penetrated the furniture industry in significant
12
volume because they are relatively new in this industry . This technique will no
doubt develop when more pressure to reduce emissions from solvent-borne coating is
applied to the industry.
Higher solids coatings are making inroads. In one case an institutional
furniture manufacturer used higher solids coating to minimize air pollution and
41
provide a coating with minimum solvent content on its product .
Emissions are also influenced by the thickness of the coating and transfer
efficiency of the coating technique used. There are minor transfer problems involved
with the use of dip coating; essentially, all of the paint solids are transferred to the
part. The dipped paint is normally returned to the dip tank. Coating loss with non-
electrostatic spraying ranges from 40 to 70 percent; with electrostatic spraying the
13
range is from 13 to 32 percent . In this industry a loss of 35 percent is probably
more realistic as an average because of the variety of parts coated. Flow coating
transfer efficiency is about 90 percent.
Emissions are also influenced by state or intrastate regulations. Only thirteen
states had statewide regulations in effect; but eight other states with a total of
twelve districts within these states, had promulgated individual district, non-
statewide regulations. Some states do not have limits on the amounts of exempt or
3-17
-------
non-photochemically reactive solvents that can be emitted. Connecticut on the other
hand is more stringent in this regard, allowing only 800 pounds per day versus the
3000 pounds per day specified by Rule 66.
3-18
-------
3.3. REFERENCES
1. 1972 Census of Manufacturers, Volume II, Industry Statistics, U. S. Department
of Commerce
2. U. S. Outlook 1977 - p 305
3. BLS Review - November 1976 - p 5
4. Springborn Laboratories' (formerly DeBell & Richardson, Inc.) survey of the
metal furniture companies.
5. Air Pollution Engineering Manual. U. S. Department of Health, Education and
Welfare; Cincinati, Ohio 1967 p 711.
6. Oge, M.T. Trip Report - Lyon Metals, Aurora, Illinois. Springborn Labora-
tories, Inc., (formerly DeBell & Richardson, Inc.) Enfield, Connecticut. Trip
Report 91, March 12, 1976.
7. Industrial Finishing Journal - July 1976 - p 22
8. The Condensed Chemical Dictionary by VanNostrand Reinhold Company 1971,
p346
9. Bruce Ocko, Modern Paint and Coating Magazine, March 1977 - p 61.
10. Oge, M.T. Trip Report - Bunting Company, Philadelphia, Pennsylvania,
Springborn Laboratories, Inc. (formerly DeBell & Richardson, Inc.) Enfield,
Connecticut. Trip Report 86, March 8, 1976.
11. Oge M. T. Trip Report - Goodman Brothers Manufacturing Company,
Philadelphia, Pennsylvania, Springborn Laboratories, Inc. (formerly DeBell &
Richardson, Inc.) Enfield, Connecticut. Trip Report 85, March 8, 1976.
12. Telephone Conversation, William Holley of Springborn Laboratories, Inc.
(formerly DeBell & Richardson, Inc.) with John Dunhan, Hanna Chemical
Coatings Company, August 25,1977.
13. Waste Disposal from paint systems. Discussed at Detroit, Michigan. American
Paint and Coating Journal. February 23, 1976 - pp 35-36.
3-19
-------
4. EMISSION CONTROL TECHNIQUES
This chapter and Chapter 6 are both analyses of available emission control
technology for the metal furniture finishing industry. The purpose of this chapter is
to define the emission reduction performance of specific control techniques, while
Chapter 6 evaluates complete systems which include finishing processes in combin-
ation with one or more emission reduction techniques.
The purpose of the control techniques as referred to in this chapter is to
minimize emissions of volatile organic compounds to the air. These compounds -
ketones, alcohols, esters, saturated and unsaturated hydrocarbons, and ethers -make
up the major portion of solvents used for paints, thinners, and cleaning materials
associated with industrial finishing processes.
There are several types of control techniques either presently in use within
the metal furniture industry or which would have utility based on technology transfer
from related industries. These methods can be broadly categorized as either "add-
ons" or "new coating" systems. Add-ons are used to reduce emissions by either
recovering or destroying the solvents before they are emitted into the air. Such
techniques include thermal and catalytic incinerators and carbon adsorbers. New
coatings refers to application methods which use coating materials containing
relatively low levels of organic solvents. Such methods include electrodeposition,
spray, dip or flow coating of water-borne paints and electrostatic spray of high solids
and powder coatings. Because of the lower solvent content of the "new" coating
materials, these application methods are inherently less polluting than processes
which use "conventional" organic solvent-borne coatings.
The following discussion characterizes the control techniques and defines the
emission reduction performance associated with each technique as applied to the
metal furniture industry.
4.1. THE ALTERNATIVE EMISSION CONTROL TECHNIQUES
4.1. L Powder Coating
On the control techniques presently in use in the metal furniture finishing
industry, powder coating is the most common. Most of the powder is being used for
outdoor furniture with lesser amounts being applied to shelves, bed and chair frames
and miscellaneous parts.
4-1
-------
While powder is generally suitable for painting metal furniture, there can be
problems of color matching. For example, there can be difficulties where
merchandise is made for resale from one manufacturer to another, particularly if one
is using a solvent-borne paint. This problem may not exist, however, where both
finishers are using the same coating.
Powder coating, although considered here as a new coating method, has been
in use for decades , fluidized-bed coating beginning in the early 1950's and
electrostatic spray in the early 1960's. Powder coating, regardless of process,
involves the application of nearly 100 percent solid materials in dry powder form: no
solvents are used, although small percentages of organics can be driven off from the
resins during curing.
Powder coating is being used throughout the industrial finishing industry for
such diverse painting applications as wire goods (baskets, racks, and shelves), piping
2 34
and tubing, fencing and posts , garden tractors, lawn equipment , and bicycles ; in
c C <7
the automotive industry powder coating is being used for topcoats ' ' , under-the-
8 9
hood parts such as oil filters and air cleaners ' as well as bumpers, trailer hitches,
and emergency brake cable guides ' ' .
Powder coating has made significant penetration into the metal furniture
finishing industry primarily in outdoor and patio furniture. One industry expert
estimates that approximately 60 companies in the metal furniture, display shelving
and office equipment industries are presently using electrostatically sprayed powder
13
for finishing , representing approximately 15 percent of the total number of powder
14
spray installations . It has been estimated that by 1980, the metal furniture and
architectural metal industries will consume approximately 12 percent of the 113
million kilograms (250 million pounds) of powdered resin that will be used annually for
13
both fluidized bed and electrostatic spray coating .
The use of powder in the metal furniture finishing industry can in general be
divided into two categories: thin-film thermosetting polymers applied from
electrostatic spray and to a lesser extent, thick-film thermoplastic materials
deposited by the fluidized bed technique.
The leading thermoset powder coating materials, are the epoxies and
14 15
polyesters ' . these materials provide hard, smooth surfaces that have excellent
adhesion to most metallic substrates. The coatings are tough, with good resistance to
abrasion and chemicals. Thermosetting acrylic is of lesser importance but is growing
in usage.
4-2
-------
These powdered thermosets are used in the metal furniture industry for such
general decorative applications as chair and bed frames, tubular metal furniture,
patio and casual furniture, office furniture, and shelving. Examples of the use of
powder in the furniture industry appear in Table 4-1.
Thermoplastic powders comprise polymers such as polyvinyl chloride ("vinyl"),
various nylons, and cellulose acetate butyrate. These materials are normally applied
in thick films typically 5 to 15 mils to heavy wear areas such as chair legs, bases and
arms; and miscellaneous parts such as springs and handles.
The three significant application techniques in use commercially for powder
coatings are: electrostatic spray, fluidized bed, electrostatic fluidized bed; the first
two are in evidence in the metal furniture industry.
4.1.1.1. Electrostatic Spray
The electrostatic powder spray process is shown schematically in Figure 4-1
35
and can be described as follows :
Powder is drawn from the hopper and carried to the gun by
compressed air. As the powder passes through the gun, it picks up an
electrostatic charge from the electrodes in the tip of the gun. The
part to be coated is grounded and at a lower potential than the
powder particles. When an electrostatic field is generated between
the tip of the gun and the part, the powder particles are attracted to
the part and adhere. As the coating forms, the part becomes
insulated and the deposited powder begins to repel additional
particles. The result is a uniform film relatively free of voids.
The powder adheres to the part until it is fused to the surface
and heat-cured in the oven. Film thickness normally varies from 1.5
to 6 mils (0.038 to 0.127 mm), depending on the preheated
temperature of the part, the particle size of the powder, the
oc
electrical potential, and the duration of the spray .
Electrostatic spray units range from relatively small manually operated job-
shop, touchup models up to large production units with several automatic reciprocat-
ing guns and complex powder recovery systems. The basic components of all units are
37
as follows :
4-3
-------
Figure 4-1 SCHEMATIC OF ELECTROSTATIC POWDER SPRAY PROCESS
38
d.
a. Powder hopper
b. Compressed air control
c. Powder injector and tube
d. Spray gun with integral high-
voltage generator
e. Deflector plate
f. Part to be coated
g. Ground
h. Power supply
i. Electrode
-------
Table 4-1. EXAMPLES OF METAL FURNITURE FINISHING
WITH POWDER COATINGS
Product Process
Stadium seating
Hospital beds
Indoor and outdoor
furniture
Hospital bed
frames and parts
Chair frames
Tubular metal
furniture
Steel tubing for
furniture
Library shelves
Metal chairs
Dinette tables
Metal furnishing parts
Patio and casual
furniture
Hospital beds
Office furniture
Shop furniture
Chair base and arms
Chairs
Hospital furnishing parts
Hospital bed handles
Process
Manual ESa
ES
Automatic
ES
Automatic
ES
Automatic
Manual
ES
Automatic
ES
Automatic
ES
Automatic
ES
ES
Manual
ES
Automatic
ES
ES
Automatic
ES
ES
FBb
FB
FB
FB
Type of Powder Reference
Thermoplastic
polyester
Nylon 11
Epoxy and Poly- 18
ester
Epoxy
Epoxy
Epoxy and thermo-
plastic polyester
Polyvinyl chloride
thermosetting polyester
Epoxy
Polyester 25
Cellulose acetate
butyrate
Epoxy 27
Polyester
Epoxy
Epoxy
Cellulose acetate
butyrate
Nylon 66
Polyvinyl chloride/
polyester
Nylon
Polyvinyl chloride
163
17
, 19
20
21
22
23
24
, 26
19
,28
29
30
31
51
21
32
28
33
Thickness
3 mils
—
1-3 mils
2-4 mils
2-3 mils
1.5 mils
2.5 mils
1.0 mils
2.2 mils
1.5 mils
—
2.5-4.0 mils
1-5 mils
—
3-8 mils
3.5-4.0 mils
6-7 mils
15 mils total
—
—
a ES - electrostatic spray
b FB- fluidized bed
4-5
-------
(a) Basic Console
The console or cabinet contains the power supply which converts
line current to high-voltage direct current; the air supply with drier;
the powder reservoir with vibrator and air fluidizer to keep the
powder fluidized so that it will flow through the hose to the gun; and
the control module for regulating air volume and pressure, voltage,
amperage, vibrator frequency in the powder reservoir, and powder
flow rate.
(b) Powder Spray Gun
A trigger switch on the gun activates both powder flow and
transfer of voltage. A deflector mounted in the nozzle of the gun
controls the spray pattern. Connected to the gun are the material
hose and high-voltage cable.
Automatic guns are similar in design construction and operation,
but are turned on and off by a master switch on the control panel.
Automatic guns are often mounted on variable-speed/variable-stroke
39
vertical reciprocators .
The number of guns in a unit generally varies from one to twelve,
and is dependent on the size and complexity of the parts to be coated,
the extent and rate of travel of the reciprocating guns, and the
conveyor speed. It is better to use several guns at a moderate output
since excessive output from a gun will lower deposition efficiency,
40
increase overspray, and clog the guns .
(c) Spray Booth
Powder spray booths are much simpler in design than normal
paint booths with floors sloped in order to recover oversprayed
powder. Guns are normally mounted in the side walls of the booth;
openings are kept small to minimize powder loss. The interior walls
are vertical and free of projections in order to minimize hang-up of
powder .
The dimensions of the booth are governed by the part size,
conveyor size, conveyor speed, and the number of guns.
4-6
-------
Figure 4-2. shows a typical booth with recovery system and
reciprocating gun. Air flow from top to bottom in the booth helps
scavenge oversprayed powder and carry it through the bottom of the
booth.
(d) Recovery System
A recovery system is also shown in Figure 4-2. Recovery of
oversprayed powder is the key to economical powder coating. Most
systems comprise a bag or tube filter, with or without one or more
cyclones. The powder goes through the cyclones first, where the
centrifugal action spins the heavier particles to the outside and
recovers them. Recovery in the cyclone is often in the range of 75 to
n be
,186
185
85 weight percent, but can be as high as 90 to 95 weight percent if
high efficiency units are used
Powder which passes through the cyclone contains primarily
smaller particles which are collected on the filter. The filter plus
cyclone remove a total of greater than 99 weight percent of the
oversprayed powder. If an additional "absolute" filter is used, a total
of approximately 99.97 percent of the powder can be removed from
186
the air stream
In paint operations where a single color is used, powder from
both the cyclone and bag filter can be reused and overall powder
42
utilization for such operations is 98 percent or better . Where color
changes are occasionally made, however, powder from the filters
must be discarded in order to prevent color contamination. For such
operations overall powder utilization is dependent on a combination
of the efficiency of the powder recovery unit and the initial transfer
efficiency of powder from the gun to the part. The effect of these
two variables on powder utilization has been shown in Table 4-2.
4-7
-------
Figure 4-2. SOPHISTICATED RECOVERY SYSTEM41
a. Reservoir and controls
b. Elevator-mounted industrial spray gun
c. High-voltage electrode and deflector plate
d. Part being coated
e. Grounded conveyor
£. Powder tube and high-voltage cable
g. Spray booth
h. Powder recovery unit
i. Exhaust fan
j. Exhaust line for powder recovery
k. Clean air returned to booth
1. Clean air exhausted to atmosphere
4-8
-------
Table 4-2. OVERALL WEIGHT PERCENT OF POWDER UTILIZED
a
Weight Fraction
Powder Recovery
a
Weight Fraction Transfer
50
65
80
80
85
90
82.5
85.7
89.2
90.1
91.8
94.6
95.2
96.4
97.5
Assuming color changes, with powder in bag filters discarded
Weight fraction deposited on the part to be painted
Normal operating parameters for powder spray units used for
49 41 4.4 4"; 4.R
metal furniture finishing are as foUows ' ' ' ' :
Preheat
Conveyor speed
Electrical output
Polarity
Compressed air output
Powder output
Powder cure
None
1.52-13.7 meters/minute
(5-45 feet/minute)26'34'22'20'18
70-90 KV DC (maxiumum)
Positive or negative
1416-7080 cu cm/sec at 146-488 kg/sq
meters (30-100 psig)
0-36 KG (0-80 lb)/hour/gun
171-232°C (340-450°F) for 4-30
minutes18'20*22'24'26
4-9
-------
The voltage on most units is variable up to 90 KV, which permits control of
42
film thickness . A low voltage will allow penetration into holes and recesses.
Although polarity is often variable, most powders are sprayed successfully with a
negative charge. An adjustable deflector on the gun also controls the spray pattern.
A narrow pattern aids penetration while broad clouds are useful for large flat
47
areas .
Powder deposition on the parts can reach 85 percent on large flat surfaces,
40
but irregularly shaped objects result in reduced transfer efficiency . Deposition can
be as low as 30 percent on wire products such as racks and baskets, but of course this
40
overspray is almost always recovered .
The following is a generalized process description based on an investigation of
several lines presently in operation in the metal furniture finishing in-
dustry18'20'24'26'28'29'31. Such systems are used for finishing metal shelves, bed
frames, chairs, springs, etc.
Most systems are nearly fully automated with the exception of loading and
unloading of conveyors, and occasional manual-spray touchup.
(1) Conveyor
All electrostatic powder spray systems investigated use con-
veyors, generally overhead types, which carry the parts to be painted
through the pretreatment and dry-off sections, paint booth, and bake
oven to the unload area. Although conveyors are used at speeds of
from 1.52 to 13.7 meters per minute (5 to 45 feet per minute) they
generally travel in the range of from 3.05 to 4.57 meters per minute
(10 to 15 feet per minute). Parts are hung on hooks at uniform
intervals as governed by the size of the parts; 0.305 or 0.610 meter
(one or two foot) spacing is common. Conveyors are normally loaded
24
by hand, but automatic loaders are in use .
(2) Pretreatment
The metal parts are generally cleaned and phosphated in a three
stage washer. The treatment is normally done by spraying the parts,
as they are conveyed, but batch type pretreatment can be used prior
29
to placing the parts on the conveyor . For heavy-duty cleaning a
wheel-o-brator can be used prior to conventional treatment.
4-10
-------
The first stage is a phosphate wash, followed by a water rinse,
and then an acid rinse, generally chromic. The wet parts are run
through a "dry-off oven for 5 to 15 minutes at temperatures of from
93 to 260°C (200 to 500°F), followed by a cool-off period. The parts
are cooled by allowing them to travel along the conveyor in the open
room for 5 to 15 minutes.
(3) Powder Spray
After the cool-off period, the parts are conveyed through the
spray booth where the powder is applied from spray guns. The spray
booths, sometimes called tunnels or chambers depending on their size
and shape, are often designed especially to accommodate the type of
part to be coated. Long booths with large wide openings are used to
coat large items with complicated shapes or are used where the mix
of part sizes and shapes varies. Where the parts are narrow, such as
in the case of metal shelves, the booth can be correspondingly narrow
(e.g. 3.65 meters long by 3.05 meters high by one meter wide or 12
O-l
feet by 10 feet by 3 feet, 4 inches wide ).
Powder coating is best suited to the finishing of flat exterior
surfaces or open frames. Due to a Faraday caging phenomenon, it is
often difficult to coat parts with recesses which are surrounded by
metal, such as interior corners of desks or cabinets. This problem can
be overcome in part by preheating the substrate, coating at a reduced
voltage, or focusing the spray directly at the problem recess.
The powder is normally applied with from two to six guns; but
04
booths with as many as 16 guns are in use . Automatic guns are the
most common, often mounted on verticle reciprocaters.
Some operations use a smaller touchup booth after the main
18 29
booth where unpainted areas are covered by manual spray ' .
Most operations recover oversprayed powder for reuse, using
cyclones and bag filters. One rather unique booth draws the exhaust
air from the top of the booth rather than from the bottom as is
commonly done. This exhaust system plus electrically charged
precipitator plates which repel powder away from the booth walls
24
permit an overall 85 per cent transfer efficiency . No powder is
recovered on this powder spray line.
4-11
-------
(4) Baking
Baking time and temperature are governed by the mass of the
coated part and the nature of the powdered polymer. Baking
schedules vary from 4 to 30 minutes at temperatures of from 171 to
232°C (340 to 450°F).
4.1.1.2. Fluidized Bed
Fluidized bed coating involves the dipping of a preheated metal part into a
tank of powder which has been intimately mixed with air to a relatively low bulk
density. The process is analogous to the conventional organic solvent-borne paint
dipping technique.
The powder is kept fluidized by passing a stream of air up through the bottom
of the tank. The bed when fluidized has the appearance of boiling water, and if the
tank is tipped, the powder bed flows like a liquid .
The powdered resin fuses and adheres to the heated part; coating thickness is
governed by the temperature and mass of the part and the dwell time in the bed.
Fluidized bed coating is generally used where a heavy durable coating is
desired with thicknesses between 6 and 60 mils. Typical applications include chain
link fence; wire baskets and shelves for use in appliances such as freezers,
refrigerators and dish washers; handles for tools and small appliances; and
48
furniture .
With the exception of the bed itself, fluidized bed powder coating is done
with conventional finishing equipment. The bed is a relatively simple apparatus as
illustrated in Figure 4-3, consisting of a tank of suitable size separated into an upper
and lower chamber by a porous divider. Air generally from a compressor or blower, is
introduced into the lower chamber where it passes uniformly through the porous
divider and into the powder bed. The powder in the upper chamber is aerated and
suspended into a "fluidized bed".
Air flow through the bed is approximately 15.2 to 61.0 cubic meters per hour
49
per square meter of plate (50 to 200 cubic feet per hour per square foot of plate). A
vibrator is generally used to keep the expansion of the bed uniform and to prevent air
from channeling through the powder.
The tank should be of sufficient size so that the parts to be coated can be
dipped below the level of the expanded powder.
4-12
-------
PREHEATED ,—L
PART TO BE
COATED
POROUS
PLATE
f I
J
R.UIOSED «S«.
-t < '
•or
AIR CHAMBER
LOW PRESSURE AIR
Figure 4-3. SCHEMATIC OF FLUIDIZED BED APPARATUS
49
4-13
-------
As with most metal finishing, the process begins with a thorough cleaning and
phosphating as described on page 4-10 after which parts are normally hung on an
overhead conveyor. For some applications requiring high adhesion with the use of
thermoplastic powders, primers are employed. These are generally organic solven-
52
borne materials applied either by dip, spray or flow coating . After leaving the
pretreatment section parts enter a dry-off/preheat oven, where the metal is heated
approximately 40 C above the melting point of the polymer, or higher if the part has
a small mass and is apt to cool rapidly between preheat and dipping . The time and
temperature of the preheat are dependent on the polymer being used and the mass of
the part. A heavy cast iron valve to be coated with epoxy might require 45 minutes
at 200°C , while a chair arm might require only 4.5 minutes at 330°C to fuse a
21
nylon coating .
To apply the powder, the preheated part is dipped into the fluidized bed; this
is done as soon as the part exists the oven in order to minimize heat losses.
Adequate dwell time and motion of the part in the bed are required in order
to obtain a satisfactory coating, free from pin holes and an "orange peel-like"
surface. Coating thickness is goverened by the dwell time in the bed; the longer the
dwell time, the thicker the coating. Typical immersion times range from 3 to 20
. 53
seconds .
Depending on the size of the operation, parts are dipped either automatically
or are removed from the conveyor on exiting the oven and dipped manually. Excess
powder is often removed from the coated parts by a blast of air, prior to post-
49
heating, or cooling of the part .
If the powder is a thermoset, or if a more uniform coating is desired with a
thermoplastic powder, the part is given a final bake.
4.1.2. Water-Borne Coatings
Of the control techniques presently in use in the metal furniture industry,
water-borne coatings next to powder are the most common. Most of the water-
bornes for furniture are being applied by electrodeposition (ED or EDP) for use as
one-coat finishes. Water-borne spray is being used to a lesser extent.
The terminology for water-borne coatings tends to be confusing; the names of
the various coating types are often misused or used synonymously. The term water-
bornes as discussed here refers to any coating material which uses water primarily as
the carrier, and is meant to distinguish such coatings from organic solvent-borne
paints.
4-14
-------
There are three types of water-borne coating materials: latex or emulsion
paints, partially solubilized dispersions, and water-soluble coatings. Table 4-3 lists
the significant characteristics of these three types of coating materials.
The majority of water-borne industrial finishes are based on partially
4 54
solubilized resins in the 3.5 to 8.0 x 10 molecular weight range and are applied by
electrodeposition (EDP). Emulsions are growing in interest for some applications,
however, because of their ability to build relatively thick films without causing
e c ec
blister . They also require no noxious amine solubilizers and no solvents .
Most of the solubilized water-borne coatings used are based on alkyd,
polyester, acrylic, modified silicone, and epoxy resins - often made crosslinkable with
57
amine resins such as hexamethoxymethyl melamine . A common method of
solubilizing is to incorporate carboxyl-containing materials such as maleic anhydride
and acrylic acid into the polymer backbone. The acids are then "solubilized" with low
molecular weight amines such as triethylamine, or to a lesser extent with potassium
57
hydroxide .
After application, solubilized coatings are baked and the amine, solvent, and
water evaporate to leave a cured film that closely resembles an organic solvent-borne
finish58.
Although the use of water-borne coatings in the metal furniture industry is
limited at this time it will probably increase. One industry consultant feels that the
market for water-borne finishes for office, home, and institutional furniture "should
59
grow well - both as ED coatings and as sprayedor dipped coatings" .
Current usage in the metal furniture and related fields includes office and shop
fifl fi1 fil fi9 fi1^ fifi R7
furniture '', shelving , computer cabinets ' , metal doors , card table legs
55 68
and chairs , and other tubular folding table frameworks .
4.1.2.1. Electrodeposition
Many of the finishes used for institutional and office furniture are applied in
_o ce CQ
very thin coats, generally 2.5 x 10 cm (1 mil) or less ' . The fact that
electrodeposition is limited to one coat application of thin films in one color makes it
an attractive finishing method for certain products in the metal furniture industry.
Examples where EDP is in use on metal furniture finishing lines can be found in Table
4-4.
4-15
-------
Table 4-3. WATER-BORNE COATINGS
Properties
Resin particle size
Molecular weight
Viscosity
Viscosity control
Solids at application
Gloss
Chemical resistance
Exterior durability
Impact resistance
Stain resistance
Color retention on
oven bake
Reducer
Washup
Latex or Emulsion
Paints
0.1 micron
up to 1 million
Partially Solubilized
Dispersions
Ultrafine
50,000 - 200,000
Low-not dependent Somewhat dependent
on molecular weight on molecular weight
Require thickeners Thickened by addition
of cosolvent
High
Low
Excellent
Excellent
Excellent
Excellent
Excellent
Water
Difficult
Intermediate
Low to medium-high
Good to excellent
Excellent
Excellent
Good
Excellent to good
Water
Water-Soluble
Coatings
20,000-50,000
Very dependent
on molecular weight
Governed by molecu-
lar weight and solvent
percent
Low
Low to highest
Fair to good
Very good
Good to excellent
Fair to good
Good to Fair
Water or water/
solvent mix
Moderately difficult Easy
Source: Industrial Finishing (July 1973) p 13
4-16
-------
Table 4-4. ELECTRODEPOSITION IN THE METAL FURNITURE INDUSTRY
Application/Product
Topcoat/shop
furniture
Topcoat/shelves
Topcoat/shop
furniture
Topcoat/institu-
tional furniture
Primer/outdoor
furniture
Topcoat/office
furniture
Tank
Capacity Paint
Liters Concentration
(Gallons) Percent Solids
37,900 10
(10,000)
53,000 7.5-8.0
(14,000)
106,000 —
(28,000)
68,100 7.9-8.1
(18,000)
79,500 —
(21,000)
9,500 —
(2,500)
Dwell Time Film Thickness
Min. cm x 10~3(mils)
2 2.54-3.05
(1.0-1.2)
2 2.54-3.05
(1.0-1.2)
3.5 2.54 (1)
— 1.78-2.03
(0.7-0.8)
— —
— —
Reference
60, 61
62
63
64
60
60
4-17
-------
Autophoretic coating, similar in nature to EDP, is not being used for metal
furniture, since the color for this paint technique is limited to black at the present
time193.
Electrodepostion is limited to waterborne coatings. During application, the
parts are immersed in a bath of low-solids water-borne coating solution; the tank or
grids on the periphery of the tank are subjected to a negative charge while the parts
are grounded. The process is analogous to electroplating; negatively charged polymer
70
is attracted to the metal item and is deposited as a highly uniform coating .
Systems of the opposite polarity can also be used.
Figure 4-4 shows a typical closed-loop electrocoating line.
In a typical EDP operation, parts are loaded on a conveyor which carries them
first through a conventional cleaning and pretreating section. An additional rinse
with deionized water is often used, but since EDP is an aqueous system dry-off
between pretreatment and finishing is not required. The washed and treated parts are
lowered automatically into the EDP tank containing the water-borne paint, normally
71 62 64
a 7 to 10 percent dispersion of a colloidal polymer ' ' . The body or part becomes
the anode of the electrical system while the tank or grids mounted in the tank
become the cathode. To avoid stripping the coating the DC current is not applied
until the part is totally submerged. Current flow through the bath causes the paint
"particles" to be attracted to the metal surface, where they deposit as a uniform
film. The polymer film that builds up tends to insulate the part and prevent further
R1 B2 71 72
deposition. Dwell time in the tank is typically li to 2 minutes ' ' ' .
The current is then shut off and the parts are raised out of the bath, allowed
to drain, rinsed in deionized water to remove "dragout", and then baked. Solids from
the dragout are collected in the rinse water and usually are returned to the EDP tank.
67 73
This recovery can result in a paint savings of from 17 to 30 percent ' , with paint
74
solids utilization approaching 100 percent . Excess water removed from the paint
74
bath with an ultrafilter , is generally used for rinsing and eventually dumped to the
sewer to control the buildup of impurities.
The conveyors, pretreatment section, and bake oven used for EDP are
70 75
conventional items; the critical components of the system are ' :
4-18
-------
Figure 4-4. TYPICAL ELECTRODEPOSITION SYSTEM DIAGRAM 159
>**.
t-1
CO
Deionized Water
Llectrodeposition
Dip Tank
Paint Supply
Rinse Tank »2
Rinse Tank S3
Paint Return
I— Ultrafiltration
Ultrafiltrate
Holding Tank
h-€T
Drain
-------
(1) Dip Tank
The dip tank is a large rectangular container generally with a
capacity of 37,850 to 113,550 liters (10,000 to 30,000 gallons),
61 fi2 fi"? fi4
depending on part size ' ' ' . The tanks are coated internally
with a dielectric material such as epoxy and are electrically grounded
CO "71 <7C
for safety ' ' . Shielded cathodes are submerged and usually run
along both sides of the tank.
(2) Power Supply
Direct current electrical power is supplied by a rectifier with a
capacity of approximately 30 to 300 volts and 300 to 750 amperes,
depending on the number of square feet per minute to be finish-
ed62'63'64.
(3) Heat Exchangers
Paint drawn from the dip tank is passed through a heat exchanger
to dissipate heat which is developed during the "painting" operation.
The temperature is normally main
24°C (+ 2°F of 68 to 75°F)62'71'76.
The temperature is normally maintained at within + 1°C of 20 to
(4) Filters
An "in-line" filter is also placed in the recirculating system to
remove dirt and polymer agglomerates from the paint.
(5) Pumps
Circulating pumps are used to keep the paint solution moving.
(6) Paint Mixing Tanks
Paint mixing tanks are used to premix and store paint solids for
addition to the dip tank as needed.
(7) Control Panel
The electrodeposition process is generally controlled from a
central control console. This panel contains all start-stop switches
plus instruments for monitoring voltage, amperage, paint tempera-
ture, and pH.
4-20
-------
Proper pretreatment can be critical to paint performance - particularly if the
substrate has grease or oil on the surface. Solvent-borne paints will generally
77 78
"dislodge" an occasional oil spot, but water-bornes will not ' . Cleaners developed
for conventional systems are generally adequate for EDP, however.
Painting in the dip tank is affected by voltage, current density, temperature,
79
dwell time, pH, and solids content .
By increasing the voltage or the temperature in the bath, the film thickness
can be increased. Excessively high voltage will cause holes in the films due to
gassing, however. Too high a temperature is also undesirable; some paints will
flocculate at temperatures approaching 90°C.
At high pH, there is a reduction in the depostion; if the pH drops below the
isoelectric point, the entire tank of paint can coagulate.
If the solids content in the tank is too high, the voltage cannot "wring" the
moisture from the deposited film; if the bath is too dilute, then the film will be thin,
_o
below 2.54x10 mm (one mil).
For successful operation of an EDP system it is necessary to monitor on a
regular basis: voltage, amperage, pH, temperature, and solids and organic solvents.
For satisfactory appearance of the final finish, it is important to rinse the parts
thoroughly after painting; the final rinse should be with deionized water.
Ultrafiltration Rinsing
A portion of the bath is pumped through an Ultrafiltration
membrane to provide permeate for rinsing of parts emerging
from the tank. The permeate collects into a tank of suitable
capacity. Permeate is delivered from the holding tank #3 for a
final rinse.
Waste Treatment
The liquid in the waste treatment tank is monitored for pH.
Such a system treats accumulated wastes from the ultrafilter
rinses and drains and raises their pH to precipitate the resin prior
to dischaging to drain. The precipitate forms a rubber-like
material in a chamber that is readily cleaned. The remaining
solution passes into the plant's waste system.
4-21
-------
Furniture parts painted with EDP are normally baked from 15 to 30 minutes
at 135 to 205°C (275 to 400°F).
Solvent emissions are related to both paint composition and production rate.
The greater the quantity of solvent in the water-borne coating, the greater the air
emissions. Solvents used are high molecular weight alcohols, added to aid in fusing
the paint particles into a continuous film.
Production in terms of square meters per hour has an influence on emissions:
the higher the rate, the greater the emissions. This rate depends on the area of the
parts, their spacing on the conveyor, and the conveyor speed.
Emissions are also influenced by coating thickness; thicker coatings will carry
a greater amount of solvent. The thickness depends on the "throwing power" used
during the deposition - i.e., the voltage and amperage applied across the electrodes.
Normally there are no transfer efficiency problems with electrodeposition; with the
74
use of ultrafilters nearly all of the paint solids are transferred to the part . There
can be dripping associated with dragout, but this material is recovered in the rinse
water and returned to the dip tank.
The emission reduction capacity of EDP is related to the solvent content of
the paint, and the percent solids of the paint as the part emerges from the bath, both
of which influence the weight of solvent associated with applying a given weight of
dry paint solids. Of course the percent emission reduction is also related to the
emission level for the solvent-borne paint being replaced, which can also vary,
depending on the percent solvent in the paint and the transfer efficiency.
4.1.2.2. Water-Borne Spray
While spray painting with water-bomes has found relatively little use in the
metal furniture industry to date, there is fairly widespread use of this technology
throughout much of the industrial finishing industry. Typical applications include
. , ^ . , . ,.80 .., ,. ^ 81.82,83 • 84 j . 85,86 .
industrial equipment ; automobile topcoats ' ' , engines , and parts ' ; farm
87 88 89 90 91
machinery ; cans ; computer cabinets ' ; business machines ; and air con-
92 68
ditioners ; as well as metal furniture .
A recent survey of 100 major appliance; air conditioner; and business,
vending, and commercial machinery firms indicates that, 15 were using water-borne
93
spray painting , compared to 11 using electrodeposition and 8 using either flow or
dip coating.
4-22
-------
Most of the solvent-borne paint presently being used for indoor home, office,
94 95
and institutional furniture is alkyd and to a lesser extent acrylic and polyester ' .
It is likely that in converting to water-borne finishes, these same binders will
continue to be used.
Since water-borne paints are readily atomized, they can be applied by air,
airless, or electrostatic spray or electrostatic disc, using either manually operated or
93 96
automatic guns ' . With both water-borne and solvent-borne paints, being
relatively low viscosity fluid systems with approximately the same solids content, few
if any modifications are generally required in order to convert from the use of one
paint to the other. Some water-bornes are corrosive due to high pH, requiring the use
of stainless steel or plastic pipes and pumps ' , and stainless steel or aluminum
spray nozzles.
Electrostatic spray presents no problems, but for safety reasons because a
highly conductive fluid is being used, pumps, lines, guns and paint supply tanks must
54
generally be insulated or isolated . One unique gun design allows for changing of the
paint particles at the gun, obviating the need for isolation of the rest of the
system
Water-borne paints are generally water-reducible coatings with some emul-
sions being used. The water reducible materials are thermosetting paints with 25 to
54 57
40 volume percent solids ' and a ratio of 82/8 to 88/12 water to organic solvent in
the volatile portion of the paint.
With water-borne paints, as with any solvent containing paint, the emission of
volatile organics into the air is dependent on the percent solvent in the paint and the
thickness of the coating that is applied.
In addition, the emissions are influenced by the number of units produced per
hour and the surface area of each unit.
One critical factor in any spray operation, a factor that can have a serious
effect not only on emissions but on cost and secondary pollutants, is transfer
efficiency - that percentage of the spray paint that actually deposits on the part.
With conventional spray being used, transfer efficiencies are normally in the range of
30 to 60 percent. If electrostatic spray is used, transfer can increase to 70 to 90
29
percent . The variation in percent transfer for a given spray technique is influenced
by part geometry and in the case of manual spray, by the spray gun operator.
4-23
-------
4.1.2.3 Water-Borne Dip
Water-borne dip coating has also found relatively little use in the metal
furniture industry to date, but as with water-borne spray coating there is increasing
use of this technology throughout the industrial finishing industry. Reports from a
recent symposium on water-borne coating systems indicate that water-borne dipping
enamels are finding use as primers and one coat finishes in industrial finishing
-3 98
applications where a nominal 2.5 x 10 cm (1 mil) thick finish is desired . Present
use of dip coating includes applications such as primers for bicycles and au-
,. 99,100,101 ^ x . . ,. ,93
tos ' ' , topcoats for major appliances, etc. .
Most of the solvent-borne finishes for metal furniture are applied by either
£C
spray or dip coating . Therefore for a finisher already applying dip coatings,
conversion to water-borne paint should be relatively simple, requiring the replace-
ment of the dip tank with a tank of stainless steel or other inert material.
One industry expert feels that water-borne dip coats should make good
59
penetration into the metal furniture and fixture market , but the occasional problem
1 no
of poor appearance due to runs and drips may slow this penetration .
The water-borne dip process is nearly identical to that for solvent-borne
materials, the major difference coming in the dry and bake schedule. As with water-
bornes applied by other methods a longer slower drying schedule is required in order
to prevent blistering of the coatings.
The factors governing emission of solvents are the same as for spray coatings
discussed above. In the case of dip coating, the transfer efficiency is nearly 100
percent with only some small losses due to dripping in some operations.
4.1.2.4. Water-Borne Flow Coating
Flow coating is a finishing technique that is used for painting a wide variety
of products including, farm equipment, appliances, machinery, electrical equipment,
93 189 190
and air conditioners ' ' , as well as furniture.
In flow coating, paint is made to flow or cascade over the part to be painted,
by squirting the paint onto the part through small nozzles. These nozzles are often
mounted in the bottom of the coating cabinet, where they create a column of paint
through which the parts must pass. Excess paint flows to the bottom of the cabinet
where it is collected and reused.
4-24
-------
Since flow coating involves the use of a fluid paint, conversion from organic
solvent-borne to water-borne materials is logical; such conversions have been made in
92 93 187
the major appliance, air conditioner ' , and trailer industries , as well as in the
188
metal furniture industry
Once again, the factors governing emission of solvent vapors to the air are
the same as for spray coating discussed above. In the case of flow coating, the
transfer efficiency is in the range of 75 to 90 percent. Hollow articles may receive a
coating inside where it is unnecessary - and therefore result in low effective transfer
efficiency.
4.1.3. Higher Solids Coatings
Higher solids coatings hold the potential of being able to apply the same
weight of paint solids with reduced emissions of volatile organic solvent. Such
coatings fall in the general categories of radiation curable systems, "high-solids
coatings", and powder coatings. Powder coatings have already been discussed
(Section 4.1.1. - page 4-1). Radiation-cured coating involves the photocuring of
mixtures of low molecular weight polymers or oligomers dissolved in low molecular
weight acrylic monomers. These formulations contain no solvent carriers and can
cure using either electron beam or ultraviolet light sources to essentially 100 percent
solids coatings ' ' . These coatings have generated little interest in the metal
furniture industry, presumably because of the health hazard associated with the spray
application of these relatively toxic monomer mixtures and the difficulties involved
in obtaining adequate cure of the paint when applied to irregularly shaped substrates.
High-solids coatings are a relatively new family of materials that is currently
being developed and investigated in the automotive, can, coil, appliance, and metal
furniture industries. The attraction of such coatings seems based on a low solvent
content, the promise of application with modified conventional finishing equipment,
and the promise of energy savings through the use of more reactive systems.
Although the traditional definition of high solids as specified in "Rule 66" indicates no
less than 80 volume percent solids , most of the people in industry are considering
everything from 50 percent to 100 percent.
There will very likely be no radically new resin binders associated with high-
solids coatings; most are modifications of their low-solids counterparts. The coatings
can be categorized as either two-component/ambient-curing or single-com-
ponent/heat-converted materials.
4-25
-------
The coatings that are of the most immediate interest are the two-
component/ambient-cure materials; they offer not only a reduced solvent content but
also a tremendous energy savings since they require little or no baking. Resin
systems being investigated include epoxy-amine, acrylic-ure thane, and ure-
thane106'107'108'109.
The heat-converted, high-solids coatings being developed include epoxy,
acrylic, polyester, and alkyd . Most contain reactive hydroxyls or carboxyls which
allow crosslinking with amino compounds such as hexamethoxy methylmelamine.
There coatings are baked at temperatures similar to low-solids counterparts -
nominally 150 to 175°C (300 to 350°F).
The most significant problem with high-solids coatings is the high working
108
viscosity of the high-solids solution (i.e., 60 to 80 volume percent) . The viscosity
can be controlled to some degree by reducing the molecular weight of the base
polymer or by using reactive diluents, but these techniques can result in a greatly
altered product with inferior properties. A more effective means of reducing
108
viscosity is to heat the coating during the application
Heated high solids can be applied as airless, air, or electrostatically sprayed
1 C A
finishes from heated equipment , and can be roll-coated. One new type of coating
apparatus, the high-speed turbine disc or bell, seems particularly well suited to the
application of high-solids coatings since the coatings can be applied without heating
of the paint160'161.
While it is generally agreed that high-solids coatings hold a great deal of
promise, they are still an emerging technology and must be considered to be still in
on §
163
1 fi2
their infancy . Of the approximately 1514 million liters (400 million gallons) of
industrial finishes consumed in 1975, less than 1 percent were high solids
Principal uses for high-solids coatings are presently in coil and can
coating . While there has been a great deal of interest in high-solids coatings in
95
the industrial finishing industry , there are only a f
furniture industry at the present tjme95.160>165'166.
95
the industrial finishing industry , there are only a few production lines in the metal
The current usage of high solids paints in the industrial finishing industry,
including the metal furniture industry, generally involves the application of "higher
i fis
solids" or intermediate solids materials, that is 40 to 55 volume percent solids
While the use of high solids coatings (i.e. 70 to 80 volume percent solids) is feasible
and has been demonstrated on at least one institutional metal furniture finishing
4-26
-------
166
line , "higher solids" coatings of 65 volume percent solids are generally considered
to be the practical upper limit at the present time for industrial finishes. For
materials above 65 volume percent solids there are often adhesion and application
problems resulting from the high viscosity and low solvent content of these paints.
4.1.4. Carbon Adsorption
Carbon adsorption as a technique for solvent recovery has been in use
commercially for several decades. Applications include recovery of solvent from dry
cleaning, metal degreasing, printing operations, and rayon manufacture . While
adsorbers have not been used in the metal furniture finishing industry they have been
used in other industrial finishing industries ' ' , and although the recovery of
coating solvents from industrial finishing operations using adsorption is not without
some technical problems, the process is essentially no different from any other being
used for solvent recovery.
The adsorption process is made possible through the use of specially
"activated" carbon, which has a fine pore structure and therefore a tremendous
surface area per unit weight - as great as 1,000,000 square meters per kilogram .
Through secondary bonding and capillary action, this carbon can adsorb onto its
surface large quantities of volatile organics.
A typical adsorption unit is shown in Figure 4-5. Air containing the organic
vapors is passed through a filter to remove particulates and then through a cooler to
reduce the temperature of the gas to no greater than 38°C. A blower forces the
vapors through one of two adsorbers, packed with activated carbon. Two units are
normally adequate for continuous operation; one unit can be operated while the other
is being regenerated.
During the course of operation, the carbon becomes saturated with organics,
and it is necessary to regenerate. The organics are desorbed from the carbon by
11B
passing either steam or hot gases through the bed . The revolatilized organics are
then recovered downstream in a condenser. The regenerated gas can also be directly
incinerated, which is always the case for hot gas regeneration.
For most industrial applications, adsorption is used to recover solvents for
reuse. Coating solvents used in industrial finishing, however, are normally complex
118 119
mixtures of aliphatics, aromatics, esters, ketones, alcohols, ect. ' . To recover
such solvents with sufficient purity for reuse would require costly fractional
4-27
-------
Figure 4-5. DIAGRAM OF AN ACTIVATED-CARBON ADSORBER SYSTEM
to
oo
Vapor laden
air inlet
Stripped air
to atmosphere
Condenser
Decanter
Filter
and
Cooler
Recovered
solvent
Water
Stripped air
to atmosphere
Low-pressure
steam
From Adsorption, by Mantell. Copyright 1945, 1951 by the
McGraw-Hill Book Company, Inc. Used with permission of the
McGraw-Hill Book Company.
-------
distillation, which is probably not economically feasible. The most practical use for
these solvents, since they are all flammable, is incineration. The heat generated can
120
be used to produce some of the steam necessary for regeneration of the adsorber
There are several variables which effect the performance of carbon adsorbers
and most are related to the adsorptive capacity of the carbon. This adsorptive
capacity, the weight of solvent that can be retained on a given weight of carbon, can
121 122
be expressed as follows ' :
V
Adsorptive capacity -
g solvent
in —
g carbon
Where V = liquid molar volume of pollutant at normal boiling point
T = absolute temperature
CQ = concentration of saturated vapor
C. = initial pollutant vapor concentration into adsorber
The liquid molar volume of a given solvent is related to both its molecular
weight and density at the boiling point. In general, the greater the V of the solvent
the higher the molecular weight and therefore the boiling point. In other words,
carbon will generally have a greater adsorptive capacity for higher boiling solvents.
For these compounds with relatively high V , adsorption will occur, but
because of their low vapor pressures desorption becomes difficult. Generally,
3
solvents with a molar volume of between 80 and 190 cm /mole present no problems
123
with adsorption and regeneration . Fortunately most of the solvents used in
industrial finishing fall within this range. Table 4-5 lists some of the problem
solvents for carbon adsorption. Of the solvents listed, nonane (a component of most
grades of mineral spirits) is commonly used in metal furniture finishing. Mineral
spirits are used in substantial proportions in many alkyd and acrylic enamels but
124
should be effectively desorbed with either super heated steam or hot gas
4-29
-------
Table 4-5. PROBLEM SOLVENTS FOR CARBON ADSORPTION
Boiling Point
Solvent Vmcm3/mo1 F
Dodecane 274 421 (216)
Undecane 251 383 (195)
2-ethylhexyl acetate 238 390 (199)
Decane 229 345 (174)
Butyl carbitol 213 448 (231)
Nonane 207 302 (150)
2,6-dimethyl4-heptanone 207 345 (174)
Diethyl cyclohexane 207
Butyl cyclohexane 207 345 (174)
1-methyl pentyl acetate 194
Diethyl cyclopentane 192 307 (152)
Nitroe thane 75 239 (116)
Propanone 74 133 ( 56)
Dichloromethane 65 104 ( 40)
Ethanol 61 173 ( 78)
Nitromethane 53 214 (101)
Methanol 42 149 ( 66)
Source: Stern, A.C. Air Pollution. Academic Press, New
York. Vol. II, Second Edition, Chapter 16 (1968)
4-30
-------
Temperature of the inlet gas stream also affects adsorptive capacity; the
higher the temperature the lower the adsorptive capacity. At temperatures in excess
of approximately 38°C, solvents which are normally adsorbed and desorbed with no
difficulty will be poorly retained by the carbon ' . Low inlet vapor concentra-
127
tion also has an adverse effect on adsorptive capacity , and of course capacity is
also affected by the surface area of the carbon as influenced by particle size and
degree of porosity.
Although adsorption will generally remove 90 percent or more of the volatile
organics from a gas stream, this performance tends to deteriorate with time as the
active sites on the carbon surface are depleted. This is shown graphically in Figure 4-
6. Although the performance begins to deteriorate after 500 minutes (i.e., effluent
concentration starts to increase), the carbon is not completely exhausted until 1000
minutes have elapsed. The overall performance of an adsorber, then, is largely
dependent on when and how completely the unit is regenerated. If the unit in the
example given is regenerated after every 500 minutes, the overall performance will
be quite high, but the cost of treatment will also be higher than with longer cycle
times as a result of more frequent regeneration. Normally there will be some trade-
off between cost and performance.
The size of a given adsorber is determined by the adsorptive capacity of the
carbon and the quantity of volatile organic to be removed. Of course the adsorptive
capacity will depend on the V of the solvent or solvent blend. In the case of mixed
solvents, the bed depth necessary to adsorb each of the vapors can be estimated from
the sun-
stream
the sum of the bed depths necessary to remove each vapor if it were alone in the air
.128
The cross-sectional area of each bed is determined from the volume of air
that must flow through the unit. A face velocity (defined as flow rate in CFM or
cubic meters per minute divided by the cross-sectional area) of 9.1 to 30 meters per
minute (30 to 100 feet per minute) is normally used to avoid excessive pressure drop
1 the
,130
129
through the bed and to get an effective utilization of the equilibrium capacity of
the bed
In the metal furniture industry the solvent emissions of greatest concern
come from two general areas, the application and flash-off area, and the bake oven.
4-31
-------
Figure 4-6. EFFLUENT CONCENTRATION CURVE OF BUTANE VAPOR
FROM AN ACTIVATED CARBON BED AS FUNCTION OF TIME
135
100
80
CO
to
a
a
c
o
•l-t
-p
n)
M
4J
c
-------
In the case of spray booths, adsorbers must be designed to handle air with a
high water vapor content. This high humidity results from the use of water curtains
on both sides of the spray booths to capture overspray. Although carbon
preferentially adsorbs organics, water will compete for available sites on the carbon
surface. Generally the relative humidity should be kept below 80 percent to minimize
131
the problem
The exhaust from the spray booths, particularly during periods of cool
132
ambient temperatures, can reach saturation with moisture . One solution to this
problem would be to preheat the moisture-laden air to lower the relative humidity to
_ 1 ^1
below 80 percent; a 4 to 5 C heating would be sufficient
Prior to adsorption, particulates from oversprayed paint have to be removed
from the air streams, since this material will coat the carbon or plug the interstices
between carbon particles. Such plugging will destroy efficiency and increase pressure
drop through the bed. Such particulates can be removed by using either a fabric
131
filter or the combination of a centrifugal wet separator plus prefilter and bag
filter134.
Another variable which should be considered in designing an adsorber for
metal furniture finishing application is the potential variability of the solvent
systems between different grades or types of paint. Although all conventional low
solids paints contain the same families of solvents (i.e., glycol ethers, esters, C0 and
o
Cg aliphatics, etc.), the various paints employed can differ widely with regard to
specific compounds and relative proportions. Solvent systems therefore could differ
in their adsorptive capacity and, as a result, their ability to be removed by the
adsorber. On lines where different grades of paint are used from time to time,
adsorbers will probably have to be over designed in adsorptive capacity.
Ovens are the second important source of solvent emissions; it has been
estimated that approximately 10 percent of the volatiles from a solvent-based paint
132
are emitted in the oven ; the remaining 90 percent goes off in the application area.
The individual solvents in an application area tend to evaporate at different
rates. The 90 percent of the solvent that is emitted in the application area will
comprise a large percentage of 'low boilers" such as acetone, butanol, toluene, etc.
The 10 percent which remains in the film as it enters the oven contains primarily less
volatile solvents. Therefore, adsorbers for ovens will have to be designed to handle a
different solvent mix than is found with the application areas. High-boiling solvents
4-33
-------
may not be consistently and completely stripped during regeneration, in which case
more frequent replacement of the carbon would be likely. In any case, hot gas or
124
super heated steam regeneration would probably be required
In the oven, high temperatures and flame contact with the volatiles can cause
polymerization of degradation products into high molecular weight resinous materials
which can deposit on and foul the carbon bed. Various high molecular weight volatiles
in the coatings such as oligomers, curing agents, or plasticizers could cause a similar
problem. Filtration and/or condensation of the oven exhaust air would be necessary
prior to adsorption in order to remove these materials.
In order to get satisfactory performance, it will also be necessary to cool the
oven exhaust to a temperature no greater than 38°C. Without cooling, many of the
125 126
more volatile organics will not adsorb but will pass through the adsorber '
4.1.5. Incineration
Incineration is the most universally suitable technique for reducing the
emission of volatile organics from industrial processes; in the industrial finishing
industry these volatile organic emissions consist mostly of solvents made up of
carbon, hydrogen, and oxygen, which can be burned or oxidized in specially
constructed incinerators into carbon dioxide and water vapor.
Industrial incinerators or afterburners are either noncatalytic (commonly
136
called thermal or direct fired) or catalytic , with sufficient differences between
the two to warrant a separate discussion for each.
4.1.5.1. Thermal Incinerators
Direct-fired units operate by heating the solvent-laden air to near its
combustion temperature and then bringing it in direct contact with a flame. A
typical unit is shown schematically in Figure 4-7. In general, high temperature and
organic concentration favor combustion; a temperature of 760°C (1400°F) is
generally sufficient for near complete combustion.
To prevent a fire hazard, industrial finishing ovens are seldom operated with
a concentration of solvent vapor in the air greater than 25 percent LEL, and some
operations - particularly ovens - in the automobile and light duty truck industry can
achieve concentrations of only 5 to 10 percent LEL. These low concentrations are
the result of high air flows necessary in order to prevent escape of oven gas at oven
openings and to prevent condensation of high-boiling organics on the inner surfaces of
137
the oven
4-34
-------
Figure 4-7.. FORCED-DRAFT SYSTEM ELIMINATING SOLVENT VAPORS
FROM SURFACE COATING PROCESS140
Process
Fumes
Coicbustor
Fan
Hot Clean
Gas
\
Cooled
Clean
Gas
I
Single-Pass
Heat Exchanger
Stack
Preheated Process Fumes
4-35
-------
Since the solvent emissions are below the combustible limit, auxilliary
heating of the air is necessary for incineration. The quantity of heat to be supplied is
dependent on the concentration of the organic in the air stream; the higher the
concentration the lower the auxiliary heat requirement because of the fuel value of
the organic.
For most solvents, the fuel value is equivalent to 4.45 gram-kilocalories per
cubic meter (0.5 BTU/scf), which translates into a temperature rise of approximately
15.3°C (27.5°F) for every percentage point of LEL that is incinerated. For an air
stream with an organic solvent content of 25 percent of LEL, the contribution from
the heat of combustion of the solvent would be approximately 115 gram-kilocalories
per cubic meter (13 BTU/scf) , equivalent to a temperature rise of 345°C (620°F).
If the desired exhaust temperature is 816°C (1500°F), then the inlet air
stream would have to be heated to only 471°C (880°F). On the other hand, if the
process air contains only 10 percent LEL, as is the case with the exhaust from
automobile bake ovens, then the solvent would contribute only 135°C (275 F) and the
air entering the incinerator would have to be preheated to 681 C (1225 F) in order to
attain the same final temperature, 816°C (1500°F).
To make thermal incineration less costly, heat transfer devices are often used
to recover some of this heat of combustion. Primary heat recovery is often in the
form of a recuperative heat exchanger, either tube or plate type, which is used to
140
preheat the incoming process fumes as illustrated in Figure 4-7 . Units of this type
are capable of recovering 50 to 70 percent of the heat from the original fuel
input140'141.
A more satisfactory type of heat recovery device and one that finds wide use
in fume incineration equipment is the regenerative heat exchanger, both refractory
140
and rotary plate types . Units of this type are capable of heat recoveries of 75 to
142 143 144
90 percent ' ' . In some cases secondary recovery is also used to convert
140
additional exhaust heat into process steam or to warm "make-up" air for the plant
There are several operating parameters which affect the emission reduction
potential of thermal incinerators; following are the most significant ones:
4-36
-------
For efficient combustion of the hydrocarbons in the air stream it
is necessary to have sufficient temperature and residence time in the
incinerator. Figure 4-8. shows the combined effect of these two
parameters. Insufficient residence time results in incomplete combus-
tion and the generation of carbon monoxide. A residence time of 0.3
to 1.0 seconds is typical.
If the air stream to the incinerator contains sulfur-, nitrogen-or
halogen-containing organics there will be a secondary pollution
problem. Incineration of these materials will produce sulfur and
nitrous oxides and acids such as hydrochloric and hydrobromic.
Fortunately none of the solvents used for metal furniture finishing
contain these elements.
Solvent type can also influence incinerator performance. While
593 to 677°C (110-1250°F) is adequate to combust most solvent
vapors, certain organics require temperatures of 760 to 816°C (1400 to
s\ 1 Q C
1500 F) for nearly complete oxidation
On a finishing line in the metal furniture industry, the two potential areas for
the use of incinerators are again on the application section and on the ovens used for
baking.
Although a survey of the metal furniture finishing industry found no
incinerators in use on bake ovens, such an application presents no significant problem.
Thermal incinerators are in place on ovens in several automotive assembly plants,
145 146 147 148 149
particularly in California ' ' , as well as in plants in the paper , can , and
coil coating industries ' . Typical emission reductions with such units is over 90
percent. Since the air exiting the ovens is generally at a temperature of 120 to
150°C (250 to 300°F), the air preheating requirements are less than they would be for
incoming air at ambient temperature.
Incinerators on the bake ovens are controlling approximately 10 percent of
the solvent emissions; the remaining 90 percent of the volatiles are emitted in the
application and flash-off areas.
Although incineration of the air from application areas is possible, our survey
revealed no applications in the metal furniture finishing industry. Because of the
relatively large air flow in spray booths, and the resulting low solvent concentration
4-37
-------
CO
oo
•M
C
0)
o
M
0)
cm
o
•H
-p
o
en
at
a
-p
c
o
CM
Figure 4-8. COUPLED EFFECTS OF TEMPERATURE AND TIME ON RATE OF POLLUTANT .OXIDATION 135
100
80
60
40
20
0
Increasing
Residence
Time
600
800
1000
Increasi
1200 1400
mperature,
1600
1800
2000
nagBte
-------
of the air stream, large quantities of natural gas or equivalent fuel would be required
to heat the vapor-laden air from near ambient to the 700 to 760°C (1300 to 1400°F)
necessary to effect near complete combustion.
4.1.5.2. Catalytic Incineration
This add-on control method makes use of a metal catalyst to promote or
speed combustion of volatile organics. Oxidation takes place at the surface of the
1 *^fi
catalyst to convert organics into carbon dioxide and water; no flame is required
A schematic of a typical catalytic afterburner is shown in Figure 4-9. The
catalysts, usually noble metals such as platinum and palladium, are supported in the
hot gas stream in such a way that a high surface area is presented to the waste
organics. A variety of designs are available for the catalyst, but most units use a
noble metal electrodeposited on a high area support such as ceramic rods or
136 152
honeycomb or alumina pellet '
As with thermal incinerators, the performance of the catalytic unit is
dependent on the temperature of the gas passing across the catalyst and the residence
time. In addition, the efficiency of the afterburners varies with the type of organic
152
being oxidized . These effects of temperature and organic type are illustrated
graphically in Figure 4-10. While high temperatures are desirable for good emission
3 649°C (
,136,152
reduction, temperatures in excess of 593 to 649°C (1100 to 1200°F) can cause serious
erosion of the catalyst through vaporization
The use of a catalyst permits lower operating temperatures than are used in
direct-fired units; temperatures are normally in the range of 260 to 316°C (500 to
600°F) for the incoming air stream and 399 to 538°C (750-1000°F) for the exhaust.
The exit temperature from the catalyst depends on the inlet temperature, the
concentration of organic, and the percent combustion. The increase in temperature
results from the heat of combustion of the organics being oxidized.
As with thermal incinerators, primary and secondary heat recovery can be
used to minimize auxiliary heating requirements for the inlet air stream and to
reduce the overall energy needs for the plant (see page 4-36. Although catalysts are
not consumed during chemical reaction, they do tend to deteriorate with time,
causing a gradual loss of effectiveness in burning the organics. This deterioration is
caused by poisoning with chemicals such as phosphorous and arsenic, which react with
the catalyst; by coating the catalyst with particulates or condensates; and by high
4-39
-------
Figure 4-9.
SCHEMATIC DIAGRAM OF CATALYTIC AFTERBURNER USING
TORCH-TYPE PREHEAT BURNER WITH FLOW OF PREHEAT
WASTE STREAM THROUGH FAN TO PROMOTE MIXING 135
Clean Hot Gases
Catalyst
Elements
Oven Fumes
Preheater
4-40
-------
Figure 4-10. EFFECT OF TEMPERATURE ON
OXIDATIVE CONVERSION OF ORGANIC VAPORS
IN A CATALYTIC INCINERATOR
135
100
Temperature, C ( F)
4-41
-------
operating temperatures, which tend to vaporize the noble metal. In most cases
153
catalysts are guaranteed for one year by the equipment supplier , but with proper
filtration, cleaning, and attention to moderate operating temperatures the catalyst
should have a useful life of two to three years ''.
Although catalytic incineration has the potential for reducing volatile organic
emissions, our survey found no units in regular use in the metal furniture finishing
industry.
While catalytic incinerators can probably be adapted to baking ovens with
relatively little difficulty, the use of these add-ons for controlling spray booth
emissions will present the same design considerations that were discussed for thermal
incinerators. These factors include high air flow, low vapor concentration, and the
need to incorporate a highly efficient heat recovery system in order to minimize the
need for auxiliary heating of inlet air.
4.2. EMISSION REDUCTION PERFORMANCE OF CONTROL TECHNIQUES
Emissions can be controlled either through the use of "new coatings" or "add-
on" control devices. The emission reduction associated with add-ons is related to the
ability of the technique to either capture or destroy the organic solvent emissions.
The emission reduction potential for new coatings, however, is related to the
quantity of volatile organic material in the "paint" before application and cure. The
emissions of any paint can be expressed quantitatively in terms of the amount of
solvent or other volatile organic emitted per unit of dry coating resin applied to the
substrate. These relative solvent emissions (RSE) can be derived from the weight
108
percent solids of the coating materials as follows :
RSE = % Organic Solvent/% Solids
It can be shown that the relative organic solvent emissions are not only
dependent on the solids content of the paint but rise exponentially as the solids
108
content is lowered
The RSE of any paint/application method is also related to the deposition or
transfer efficiency; that is, the percentage of the paint used that actually deposits on
the substrate. For spray application, 30 to 60 percent is normal when using air or
airless spray, while the electrostatic spray techniques will permit depositions of 60 to
90 percent. The RSE then can be expressed as:
RSE = % Organic Solvent/(% Solids) (% Deposition)
4-42
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4.2.1. Powder Coating - Electrostatic Spray
There is a tremendous emission reduction potential associated with the use of
powder coating materials which are nearly 100 percent solids.
Some powders emit small percentages of volatile organics during fusion or
cure, and the type and amount tends to vary with the generic type of binder used.
For thermosetting powders, the emission of organic volatiles for various resins in
weight percent is as follows: Epoxy - 0.5% to 3.0%; polyester (urethane type) 2.0% to
4.0%; polyesters (other types) - generally less than 1%; and acrylics - 0.5% to
1.0% ' . For thermoplastic powders such as polyvinyl chloride and cellulose
acetate butyrate, organic volatile emissions can run as high as 5 to 10% due to
184
evaporation of plasticizers from the powders during cure
With electrostatic spray of powder coatings, the powder which does not
deposit on the part to be painted is mostly contained in the spray booth. With
properly designed equipment, the oversprayed powder can be recovered, providing
overall transfer efficiencies in the range of 83 to 98 percent. See Table 4-2, page
9. The RSE when adjusted for transfer efficiency becomes 0.021 to 0.134; and
when compared against conventional solvent-borne lacquers and enamels, there is a
potential emission reduction in the range of 94 to 99%.
4.2.2. Powder Coating - Fluidized Bed
The same basic emission reduction considerations that were presented for
electrostatic spray of powder coatings apply to fluidized bed coating.
In general, the powder, other than that deposited on the parts, is contained in
the bed. A small amount of unfused powder is generally carried with the coated part,
however. This powder is usually blown-off and recovered.
Overall emission reduction then is again high, in the range of 94 to 99
percent.
4.2.3. Electrodeposition of Water-Bornes
The electrodeposition process, as described on page 4-15 has three possible
sources of organic solvent emission: the painted substrate as it is baked, evaporation
from the surface of the EDP tank, and evaporation of organic solvent from the
cascading rinse water and the drain.
4-43
-------
The paint films on the substrates are approximately 95 percent solids as they
emerge from the bath. The remaining 5 percent is primarily water with only 3 to 5
1 *\fi
percent of the volatiles as organic solvent
Another more likely source of fugitive emissions is escape of the organic
solvent into the rinse water. During operation, a portion of the paint from the EDP
tank is pumped through an ultrafilter; the permeate is generally is used for rinsing
purposes, while the paint concentrate is returned to the tank. Since ultrafiltration
157 158
will remove nothing smaller than 500 molecular weight ' , a portion of the
1 ^fi
water-miscible organic solvents such as alcohols and glycol ethers , which have
molecular weights under 150, will likely end up in the permeate.
The permeate is then used for spray rinsing where the high surface area of
the spray is conducive to evaporation. Depending on the water requirements for the
closed loop system, some of the permeate is sent to the drain. It is possible that
much of the organic solvent may be lost in this manner.
Since the quantities of organic solvent involved with EDP are quite small by
comparison with organic solvent-borne finishes, there has been no effort to our
knowledge to quantify these fugitive emissions.
The RSE, regardless of the source of the emissions, can be related to the
organic solvent content of the paint. Most EDP paints are supplied with an organic
solvent to solids ratio of 0.06 to 0.12 by weight. Since transfer efficiency is
essentially 100 percent, the RSE is also 0.06 to 0.12. These RSE translate into
percent emission reductions of 97.7 to 98.8 percent when compared against
conventional enamels.
4.2.4. Water-Borne Spray
In considering emission reduction for water-borne spray coatings, it is
necessary to assess the effect of organic solvent content and solids content of the
paint as well as transfer efficiency for not only the water-borne but also the organic
solvent-borne paint which it is replacing.
For spray painting the transfer efficiencies cover a broad spectrum, going
191
from 30 to 95 percent . These efficiencies are influenced by the type of spray
method; i.e. conventional air or airless spray, electrostatic air or airless spray or
centrifugally atomized electrostatic spray using either a disc or bell, with
electrostatic techniques giving much greater transfer efficiencies than the conventio-
nal techniques. Transfer is also influenced by the geometry of the parts to be coated,
4-44
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with higher efficiencies for large flat surfaces and lower efficiencies for open
structures such as chairs or bed frames. Finally, the efficiency can be influenced by
the individual operator in those cases where manual spray is employed.
Table 4-6 shows the combined effects of solids content, transfer efficiency
and solvent content of the paint on the emission reduction potential of water-borne
spray coatings when compared against their organic solvent-borne counterparts.
Emission reductions are shown for two types of water-bornes, containing a volume
ratio of either 88/12 or 82/18 water to solvent in the volatile portion of the paint.
These paints are compared against a 35 volume percent solids content organic
solvent-borne paint applied at both 65 and 80 percent transfer efficiency. In the case
of both the water-borne and solvent-borne paints, a solids content of 35 volume
percent as applied from the gun was assumed.
Table 4-6.PERCENT EMISSION REDUCTION FOR
WATER-BORNE COATINGS APPLIED BY SPRAY TECHNIQUES
Percent Emission Reduction by Type of Water-Borne Coating
Versus Organic Solvent-Borne Versus Organic Solvent-Borne
Paint at 65% Paint at 80%
Water-Borne Transfer Efficiency Transfer Efficiency
Transfer Efficiency 88/12 (1) 82/18 (1) 88/12 (1) 82/18 (1)
% Water/Solvent Water/Solvent Water/Solvent Water/Solvent
50 84.4 76.6 80.8 71.3
65 88.0 82.0 85.2 77.9
80 90.2 85.4 88.0 82.0
90 91.3 87.0 89.3 84.0
(1) Volume ratio of water to solvent in the volatile portion of the paint with 35 volume
percent solids as applied in both water-borne paints.
One paint supplier estimates that an emission reduction in the range of 72 to
84 percent will result from substituting water-bornes for organic solvent-borne
enamels in spray applications. See Table 4-7.
4-45
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Table 4-7. REDUCTION OF ORGANIC SOLVENT EMISSIONS
92,400 Square Meters (1,000,000 Square Feet)
Sprayed at 65 Percent Efficiency
Approximately 30 Percent Volume Solids
Liters (Gallons) of
Organic Solvent Percent
Coating Type Emitted Reduction
Convention enamel 10,931 (2,888)
Water base, 33 percent
organic solvent 2,861 ( 756) 72
Water base, 18 percent
organic solvent 1,560 ( 412) 84
Source: SME Technical Paper FC74-639, 1974. Page 3
4.2.5. Water-Borne Dip and Flow Coatings
As with water-borne spray coatings, the emission reduction potential is
influenced by the solids content and solvent content of both the water-borne paint
and the solvent-borne material which it is replacing as well as the transfer
efficiences for both.
The transfer efficiencies for dip coating are in the range of 70 to 80 percent
191 192
compared to 90 to 95 percent for flow coating . The effect of these transfer
efficiences on emission reduction for two types of water-borne coatings compared
against an organic-solvent-borne paint, is shown in Table 4-8. For both water-borne
and solvent-borne paints, we have assumed 25 volume percent solids as applied. We
have also assumed 80 percent transfer efficiency for solvent-borne dip coating and 95
percent efficiency for solvent-borne flow coating.
4-46
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Transfer
Efficiency
%
70
80
90
95
88/12 (2)
Water/Solvent
86.3
88.0
87.3
88.0
82/18 (2)
Water/Solvent
79.4
82.0
81.0
82.0
Table 4-8. PERCENT EMISSION REDUCTION FOR
WATER-BORNE COATINGS APPLIED BY DIP AND FLOW COATING
Percent Emission
Reduction by Coating Type (1)
Coating Process
Dip
Flow
(1) Compared against a 25 volume percent solids organic solvent-borne
enamel at 80 percent transfer efficiency for dip and 95 percent for
flow coating.
(2) Volume ratio of water to solvent in the volatile portion of the paint
with 25 volume percent solids in both water-borne paints.
4.2.6. Higher Solids Coatings
To determine the emission reduction potential associated with higher solids
coatings, the RSE of various solids content paints in the range of 30 to 80 volume
percent were compared against the RSE organic solvent-borne paint with 28 volume
percent solids. In preparing these estimates, the deposition or transfer efficiency was
also taken into consideration. Application by air spray (50 percent deposition) and
electrostatic spray (80 percent deposition) was compared against application of
conventional solvent-borne paints with air spray.
Figure 4-11 shows that if 28 volume percent solvent-borne coatings were
replaced by higher solids coatings of 60 volume percent solids, then an emission
reduction of 74 to 84 percent would be possible.
If the same 28 volume percent paint were replaced by an 80 volume percent
solids high solids coating then there would be an emission reduction of greater than 90
percent.
4-47
-------
Figure 4-11. EMISSION REDUCTION POTENTIAL (PERCENT) WITH USE OF
HIGHER SOLIDS COATINGS IN PLACE OF 28 VOLUME PERCENT SOLVENT-BORNE PAINT
(50 PERCENT DEPOSITION EFFICIENCY)
100
rfk
oo
C
O
•H
•P
O
3
•O
c
O
•H
Ul
01
•H
a
(U
O
M
0)
a.
80 -
% Deposition Efficitincy
30 40 50 60 70 80
Volume Percent Solids Content of Paints
-------
4.2.7. Incineration
Incineration is currently being used to control solvent emissions in such
finishing industries as paper148, fabric174, wire175' 176, can149'177, coil150'151
coating, and auto finishing 5»146. Field investigations indicate that incineration,
both thermal and catalytic, is capable of removing at least 90 percent of the solvents
from exhaust air streams142'146'175'176'178'179'180.
4.2.8. Carbon Adsorption
169 170 171
Carbon adsorption is being used successfully in the paper ' ' and
172
fabric industries for controlling solvent emissions, and has been evaluated on a
pilot scale in the automobile industry where is is acknowledged to be capable of 85
percent or greater emission reduction when used for solvent emissions from spray
booths181'182'183.
4-49
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4-53
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84. Schrantz, J. Water-Reducible Electrostatic Spray Brings Cost Reduction.
Industrial Finishing. 50(7):26, July 1974.
85. Electric Wheel Converts to Water-Borne Alkyd Enamel. Industrial Finishing.
52(12):50, December 1976.
86. Schrantz, J. Truck Wheels Get Water-Base Aluminum-Colored Coating.
Industrial Finishing. 50(10):44, October 1974.
87. Thompson, M.S. Trip Report - J.I. Case Division, Tenneco, Racine, Wisconsin.
Springborn Laboratories (formerly DeBell & Richardson) Enfield, Connecticut.
Trip Report 98, April 2, 1976.
88. Strand, R.C. Water-Borne Coatings In Metal Packaging. Preprints, NPCA
Chemical Coatings Conference, Water-Borne Session, 17-42, April 23, 1976.
89. Kloppenburg, W.B. Trip Report-Control Data Corp., Arden Hill, Minnesota.
Springborn Laboratories (formerly DeBell <5c Richardson) Enfield, Connecticut.
Trip Report 136, May 26, 1976.
90. Vierling. E.J. Conversion to Water-Reducible Paint. Preprints, NPCA Chemical
Coatings Conference, Water-Borne Session, 51-61, April 23, 1976.
91. Heffron, W.H. Conversion To Water-Borne Coatings At Pitney-Bowes. Preprint
NPCA Chemical Coatings Conference, Water-Borne Session, 63-69, April 23,
1976.
92. Kloppenburg, W.B. Trip Report - Singer Company, Auburn, New York.
Springborn Laboratories (formerly DeBell <5c Richardson) Enfield, Connecticut.
Trip Report 144, July 21, 1976.
93. Consdorf ,A.P. Which Way Will You Go On Finishing? Appliance Manufacturer.
25(6):43-49, April 1977.
94. Holley, William, H. Springborn Laboratories, Inc., Enfield, Connecticut. Memo
to Robert Diehl covering phone conversation with J.J. Bracco, Mobay
Chemical Company, August 23, 1977.
95. Holley, William H. Springborn Laboratories, Inc., Enfield, Connecticut. Memo
to Robert Diehl Springborn Laboratories covering phone conversation with L.
LeBras, PPG Industries, Inc. August 24, 1977.
96. The Latest in Water-Borne Coatings Technology. Industrial Finishing. 51(9):48,
September 1975.
4-55
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97. Waste Disposal from Paint Systems Discussed at Detroit Meeting. American
Paint and Coatings Journal. 6£(37):35-36, February 23, 1976.
98. Water-Borne Coating Systems Are Maturing. Industrial Finishing. 53(5):41.
99. Oge.M.T. Trip Report-Schwinn Bicycle Company, Chicago, Illinois. Springborn
Laboratories, (formerly DeBell
-------
113. Elliott, J.H., N. Kayne, and M.F. Leduc. Experimental Program for the Control
of Organic Emissions from Protective Coating Operations. Report No. 7. Los
Angeles APCD, 1961.
114. Lud, H.F. Industrial Pollution Control Handbook. New York. McGraw-Hill,
1971. 13-13 and 19-10.
115. Mantel, C.L. Adsorption. New York. McGraw-Hill, 1951. 9-10.
116. Danielson, J.A. Air Pollution Engineering Manual. Cincinnati, Ohio. Public
Health Service Publication 999-AP-40, 1967. 196.
117. Mantell, C.L. Adsorption. New York. McGraw-HilL 1951. 232.
118. Larson, E.C. and H.E. Sipple. Los Angeles Rule 66 and Exempt Solvents.
Journal of Paint Technology. 39(508):258-264, May 1967.
119. Ellis, W.H., et al. Formulation of Exempt Replacements for Aromatic Solvents.
Journal of Paint Technology. 41(531):249-258, April 1969.
120. Mattia, M.M. Process for Solvent Pollution Control. Chemical Engineering
Progress. 66(12):74-79, 1970.
121. Grant, R.M., M.Manes, and S.B. Smith. Adsorption of Normal Paraffins and
Sulfur Compounds on Activated Carbon. AIChE Journal. 8(3):403,1962.
122. Robell, A.J., E.V. Hallow, and F.G. Borgardt. Basic Studies of Gas-Solid
Interactions. Lockheed Missiles and Space Company. Report 6-75-65-22, 1965.
123. Cavanaugh, E.G., G.M. Clancy, and R.G. Wetherold. Evaluation of a Carbon
Adsorption/Incineration Control System for Auto Assembly Plants. Radian
Corporation; Austin, Texas. EPA Contract 68-02-1319, Task 46. May, 1976, 26.
124. Cavanaugh, E.G., G.M. Clancy, and R.G. Wetherold. Evaluation of a Carbon
Adsorption/Incineration Control System for Auto Assembly Plants. Radian
Corporation; Austin, Texas. EPA Contract 68-02-1319, Task 46. May 1976. 27.
125. Grandjacques, B. Air Pollution Control and Energy Savings with Carbon
Adsorption Systems. Calgon Corporation Report APC 12-A, July 19, 1975.
126. Lee, D.R. Activated Charcoal in Air Pollution Control. Heating, Piping and Air
Conditioning. 76-79, April 1970.
127. Lund, H.F. Industrial Pollution Control Handbook. New York. McGraw-Hill,
1971, 5-20.
128. Cavanaugh, E.G., G.M. Clancy, and R.G. Wetherold. Evaluation of a Carbon
Adsorption/Incineration Control System for Auto Assembly Plants. Radian
Corporation; Austin, Texas. EPA Contract 68-02-1319, Task 46. May 1976. 28-
29.
4-57
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129. Package Sorption Device Systems Study. MSA Research Corporation; Evans
City, Pennsylvania. EPA-R2-73-202. April 1973.
130. Lund, H.F. Industrial Pullution Control Handbook. New York. McGraw-Hill,
1971, 5-21.
131. Cavanaugh, E.G., G.M.Clancy, and R.G. Wetherold. Evaluation of a Carbon
Adsorption/Incineration Control System for Auto Assembly Plants. Radian
Corporation; Austin, Texas. EPA Contract 68-02-1319, Task 46. May 1976. 32.
132. Sussman, Victor H. Ford Motor Company, Dearborn, Michigan. Letter to R.G.
Wetherold, Radian Corporation, dated March 15, 1976.
133. Handbook of Chemistry and Physics. Weast, R.C. (ed.) Cleveland, The
Chemical Rubber Company. 1964. E-26.
134. Roberts, R.E. and J.B. Roberts. An Engineering Approach to Emission
Reduction in Automotive Spray Painting. Proceedings of the 57th APCA
Annual Meeting. 26(4):353, June 1974.
135. Stern, A.C. Air Pollution. New York. Academic Press. Volume II, Second
Edition, Chapter 16, 1968.
136. Lund, H.F. Industrial Pollution Control Handbook. New York. McGraw-Hill,
1971, 5-27 to 5-32.
137. Conversation between Fred Porter, Ford Motor Company, Dearborn, Michigan,
and EPA-CTO, Research Triangle Park, North Carolina.
138. Stern, A.C. Air Pollution; Vol. Ill, Sources of Air Pollution and Their Control.
New York. Academic Press, 1968.
139. Benforado, D.M. Air Pollution Control by Direct Flame Incineration in The
Paint Industry. Jurnal of Paint Technology. 39_(508):265, May 1967.
140. Lund, H.F. Industrial Pollution Control Handbook. New York. McGraw-Hill,
1971, 7-8, to 7-11.
141. Heat Recovery Combined with Oven Exhaust Incineration. Industrial Finishing.
52(6): 26-27.
142. Re-Therm Thermal Oxidation Equipment. Product Bulletin REE-1051-975-15M.
Reeco Regenerative Environmental Equipment Company, Inc., Morris Plains,
New Jersey.
143. Young, R.A. Heat Recovery: Pays for Air Incineration and Process Drying.
Pollution Egineering. 7X9):60-61, September 1975.
144. Can Ceramic Heat Wheels Do Industry a Turn? Process Engineering. 42-43,
August 1975.
4-58
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145. Gabris, T. Trip Report - Ford Motor Company, Truck Plant, Milpitas,
California. Springborn Laboratories (formerly DeBell
-------
159. Loop, P.M. Automotive Electrocoat. Preprints, NPCA Chemical Coatings
Conference, Electrocoat Session. 81, April 22, 1976.
160. Holley, William H., Springborn Laboratories, Inc. (formerly DeBell & Richard-
son, Inc.), Enfield, Connecticut. Memo to Robert Diehl, Springborn Labora-
tories, covering phone conversation with J.A. Scharfenberger, Ransburg
Corporation, Indianapolis, Indiana, August 29, 1977.
161. Sames Discatron PPH 405, Technical Leaflet PPH 405, Interred Corporation,
Stamford, Connecticut, February 1977.
162. Price, M.B. High Solids Coatings - Where Can They Be Used. Preprints, NPCA
Chemical Coatings Conference, High Solids Session. 37, April 22, 1976.
163. Mazia, J. Technical Developments in 1976. Metal Finishing. 75(2):74-75,
February 1977.
164. Scharfenberger, J.A. New High Solids Coating Equipment Offers Ecolo-
gy/Energy Advantages. Modern Plastics. 53(2):52-53, February 1976.
165. LeBras, L.R. - PPG Industries Inc., Pittsburgh, Pennsylvania. Letter to W.H.
Holley, Springborn Laboratories, Inc. (formerly DeBell & Richardson), dated
September 16, 1977.
166. Oge, M.T. - Trip Report - Simmons Company, Munster, Indiana. Springborn
Laboratories, Inc. (formerly DeBell <5c Richardson, Inc.), Enfield, Connecticut.
Trip Report 41. January 28, 1976.
167. Holley, William H. - Springborn Laboratories, Inc. (formerly DeBell &
Richardson, Inc.), Enfield, Connecticut. Memo to Robert Diehl, Springborn
Laboratories, Inc., covering phone conversation with George Wilhelm, Ashland
Chemical Company, Columbus Ohio, August 24,1977.
168. Holley, W.H. Springborn Laboratories, Inc. (formerly DeBell
-------
172. McCarthy, R.A. Trip Report - Raybestos-Manhattan, Inc., Mannheim,
Pennsylvania. Springborn Laboratories, Inc. (formerly DeBell <5c Richardson,
Inc.), Enfield, Connecticut. Trip Report 77. February 26, 1976.
173. Gabris, T. Trip Report - American Can Company, Lemoyne, Pennsylvania.
Springborn Laboratories, Inc. (formerly DeBell & Richardson, Inc.), Enfield,
Connecticut. Trip Report 89. March 11, 1976.
174. McCarthy, R.A. Trip Report - DuPont Corporation, Fabric and Finishes
Department; Fairfield, Connecticut. Trip Report 130. April 30, 1976.
175. Kloppenburg, W.B. Trip Report - Phelps Dodge Magnet Wire; Fort Wayne,
Indiana. Springborn Laboratories, Inc. (formerly DeBell & Richardson, Inc.),
Enfield, Connecticut. Trip Report 113. April 7, 1976.
176. Kloppenburg, W.B. Trip Report - General Electric Company; Schenectady,
New York. Springborn Laboratories, Inc. (formerly DeBell
-------
184. Holley, William H. - Springborn Laboratories, Inc. (formerly DeBell &
Richardson, Inc.). Enfield Connecticut. Memo to Robert Diehl, Springborn
Laboratories, Inc., covering telephone conversations with Jim Pfeifer, Pratt
and Lambert, Buffalo, New York and Tim Birdsall, Warsaw Indiana. October
18, 1977.
185. Miller, E.P. and Taft, D. D. Fundamentals of Powder Coating. Dearborn,
Society of Manufacturing Engineers, 1974. p 95.
186. Holley, William H. - Springborn Laboratories, Inc. (formerly DeBell <5c
Richardson, Inc.). Enfield, Connecticut. Memo to Robert Diehl, Spingborn
Laboratories, Covering conversation with Richard Hammel. Interred
Corporation. Stamford Connecticut. November 1, 1977.
187. Switching to a Water-Borne Flow Coat System. Finishing Highlights, p 16-19,
March/April 1976.
188. Flow Coating Water Base Paint. Data Sheet F-52. George Koch Sons, Inc.
Evansville, Indiana.
189. Oscicator Flow Coating System. Data Sheet F-27. George Koch Sons, Inc.
Evansville, Indiana.
190. Flow-Coating Process of Paint Application. Data Sheet F-24. George Koch
Sons, Inc. Evansville, Indiana.
191. Brewer, G.E.F. Painting Waste Loads Associated with Metal Finishing.
Journal of Coatings Technology. 49(625) : 50, February 1977.
192. Automatic Air Electrostatic Gun For Applying Water-Borne Coatings—Without
System Isolation. Products Finishing. 39(11): 98, August 1975.
193. Gabris, T. Springborn Laboratories, Inc. (formerly DeBell <3c Richardson, Inc.),
Enfield, Connecticut. Memo to Robert Diehl, Springborn Laboratories
covering phone conversation with Fred Henning, Amchem Products, Inc.
November 15, 1977.
4-62
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5. MODIFICATION AND RECONSTRUCTION
Proposed standards apply to all affected facilities constructed or modified
after the date of proposal of the proposed standards. Provisions applying to
modification and reconstruction were originally published in the Federal Register on
December 23, 1971. Clarifying amendments were proposed in the Federal Register on
October 15, 1974 (39 FR 36946), and final regulations were promulgated in the
Federal Register on December 16, 1975 (40 FR 58416).
Modification is defined as "any physical change in, or change in the method of
operation of, an existing facility which increases the amount of any air pollutant (to
which a standard applies) emitted into the atmosphere by that facility or which
results in the emission of any air pollutant (to which a standard applies) into the
atmosphere not previously emitted". Reconstruction occurs when components of an
existing facility are replaced to such an extent that:
(1) The fixed capital cost of the new components exceeds 50
percent of the fixed capital cost that would be required to
construct a comparable entirely new facility, and
(2) It is technologically and economically feasible to meet the
applicable standards.
There are certain circumstances under which an increase in emissions does not
result in a modification. If a capital expenditure that is less than the most recent
annual asset guideline repair allowance published by the Internal Revenue Service
(Publication 534) is made to increase capacity at an existing facility and also results
in an increase in emissions to the atmosphere of a regulated pollutant, a modification
is not considered to have occurred.
An increase in working hours - i.e., from one to two-shift operation - or an
extension from 8 hours to 10 hours per shift would also increase solvent emissions per
day. This situation, however, is also not considered a modification under the
definitions set forth in 40 FR 58416, December 16, 1975.
5-1
-------
The purpose of this chapter is to identify potential modifications and
reconstructions of affected facilities, and any exemptions or special allowances
covering changes in existing facilities that should be considered. Exemptions from
the regulations may be based on availability of technology and economic con-
siderations.
As will be seen, many of the possible changes do not qualify as modifications
by strict definition. They are, however, potential causes of increased solvent
emission and as such should be discussed.
5.1. POTENTIAL MODIFICATIONS
The following changes in materials or formulations could cause increased
solvent emissions but would qualify primarily as alternate raw materials, not as
modifications, under the above definition unless capital expenditures are required to
effect the change so as to qualify as a reconstruction.
(1) Lower Solids Coatings
If a change is made from a higher solids to a lower solids coating-
e.g., from an enamel to a lacquer - more material, hence more solvent,
will be used to maintain the same dry coating thickness. While a change
in the direction of lower solids is unlikely; it could occur in any one
plant as a result of changing paint systems or colors. It is unlikely,
however, that any major capital expenditures to equipment would be
required.
(2) Use of Higher Density Solvent
Regulations normally restrict the number of pounds of solvent
which can be emitted. A change in the density of the solvents used,
even if the volumetric amounts used were the same, would result in
more pounds or kilograms being emitted. Again, this could be construed
as a raw-material substitution and hence not a modification, as no
major capital expenditures would be involved. Such substitutions might
come about as a result of solvent shortages, attempts to cut paint costs,
or efforts to incorporate less photoreactive solvents.
5-2
-------
(3) Increased Thinning of Coatings
A change to a higher viscosity coating could result in an increased
use of solvents for thinning the coating to proper application consis-
tency.
While these three cases can be considered as raw material substitutions, they
are not of themselves considered to be modifications. The phrase "bubble concept"
has been used in Title 40 FR 58416, to refer to a trade-off of emission increases from
one facility undergoing a physical or operational change with emission reductions
from another facility in order to achieve no net increase in the amount of any air
pollutant (to which a standard applies) emitted into the atmosphere by the stationary
source as a whole.
Title 40 FR 58416 states: "In those cases where utilization of the exemptions
under Paragraph 60.14 (e) (2), (3), or (4) as promulgated herein would effectively
negate the compliance measures originally adopted, use of those exemptions will not
be permitted."
Other changes that could be made that could result in increased solvent
emission include:
(4) Change to Larger Parts
If part sizes were increased and the same production rates were
maintained, more coating materials would be used. With the diversity
of products produced by the metal furniture industry, it is somewhat
difficult to see why this could occur unless a manufacturer began
production of large parts such as desks or panels that he had not
produced before.
Coating lines in this industry, however, are generally equipped to
handle many size parts hence such a change would not qualify as a
modification per se. If extensive capital expenditures were involved,
such a change could be classified as a reconstruction.
(5) Change to Thicker Coatings
A change to a thicker coating, other factors remaining constant,
could result in increased solvent emission. Such a change could result
from a desire to increase durability or resistance to outdoor exposure.
Most metal furniture manufacturers, especially of office furniture,
apply as thin a coating as possible, however.
5-3
-------
(6) Reduced Deposition Efficiency
Increased overspray because of a process modification such as a
switch from electrostatic spray to conventional spray would result in
increased emission. For economic reasons if for nothing else, however,
a switch in such a direction is unlikely except possibly as a temporary
measure.
(7) Additional Coating Stations
If for any reason additional coating stations were added, emissions
would be increased. It is possible that new paint systems could result in
such a change. This could involve a reconstruction or a new facility
and, as such, would be subject to regulation.
(8) Substitution of Equipment
There can be cases where in existing sources, coating line
configurations are of a temporary nature to perform a custom coating
job. Certain custom coaters in the metal furniture industry perform
metal coating services only. These services are offered to metal
furniture manufacturers on a contract basis. In the course of this type
of business, the coating line configuration may be changed to meet
requirements of a specific job. For example, existing line components
such as spray booths and dip tanks may be interchanged to accomodate
different jobs. As another example, existing ovens may be lengthened
or shortened for each job. The aforementioned changes will not be
considered to constitute a modification. It is the intent to allow the
custom coater to make changes of this nature for short-term contract
business without invoking compliance with new source performance
standards.
Installation of a line or affected facility previously used at another
plant site, however, will require compliance with new source perfor-
mance standards.
5-4
-------
5.2. RECONSTRUCTION
Spray booths and bake ovens used in coating metal furniture last ten to twenty
o
years and are not replaced before that time unless process changes dictate it. In
some cases a line may be moved to another location within the plant and booths or
ovens may fall apart necessitating some rebuilding.
Reconstructions would include replacement of spray booths either because of
deterioration or because of more advanced design such as the addition of more
automatic spraying or electrostatic spraying, if not already being used.
A line could be made longer or faster to permit increased production. This
would be considered a reconstruction as long as the requirements outlined in the
beginning of this chapter are met.
Ovens could be replaced with more efficient models or to accomodate new
energy sources such as electricity.
Changing coating application methods such as from dip coating to electrostatic
spray would qualify as a reconstruction, again if requirements were met.
It should be noted that according to 40 FR 58416 that an existing facility, upon
reconstruction becomes an affected facility and hence subject to regulation
irrespective of any change in emission rate.
It should also be noted that according to 40 FR 58416, Part 60, the decision as
to whether a reconstructed facility can meet applicable standards both technologic-
ally and economically rests with the EPA Administrator. For example, if the
equipment being replaced does not emit air pollutants, it may be determined that
controlling the components that do emit air pollutants is not reasonable considering
cost, and standards of performance for new sources should not be applied. As another
example, if there is insufficient space after the replacements at an existing facility
to install the necessary air pollution control system to comply with standards of
performance, then reconstruction would not be determined to have occurred.
5.3. CONSTRAINTS
Probably the greatest physical constraint to switching to new coating systems
with lower solvent emissions in existing facilities is the added space requirements of
some of the systems. The seriousness of this constraint will, of course, vary from line
to line or plant to plant. Plants with very tight space requirements might find it
difficult to fit in the longer oven and flash-off area required by water-borne spray
systems. Electrodeposition tanks are long to allow the necessary immersion time and
rinse area.
5-5
-------
Add-on controls for controlling bake oven emissions such as incinerators or
carbon adsorbers are relatively small and usually can be mounted on top of the oven.
It could be difficult if space were tight to find room for a large carbon adsorber to
handle spray booth emissions.
Incinerators, especially if used for controlling spray booth emissions, use a
great deal of fuel even with heat recovery in many cases. This constraint is
considered very sensitive in this era of energy shortages.
5-6
-------
5.4- REFERENCES
1. Holley, W. Springborn Laboratories, Inc. (formerly DeBell & Richardson, Inc.),
phone call to PPG Industries, Inc. August 25, 1977.
2. Oge, M.T. Springborn Laboratories, Inc. (formerly DeBell <5c Richardson, Inc.),
Trip Reports and Guidelines 41,72,86,100,103, and 108.
5-7
-------
6. EMISSION CONTROL SYSTEMS
The purpose of this chapter is to identify alternative emission control systems
and finishing processes for typical metal furniture finishing lines. In Chapter 4 the
performance of available emission control technology for coating operations in the
metal furniture industry was discussed and evaluated.
Eleven alternatives (A-2 through A-7, and B-2 through B-6) for controlling or
reducing emissions for metal furniture coating operations have been identified and
are listed in Tables 6-1 and 6-2.
There are a variety of sizes of coating lines used in the metal furniture
industry and therefore it would be impossible to show these systems in place for all
sizes of lines. To illustrate the application of these systems it was necessary to
design model coating lines where emission reductions could be quantified in terms of
percent relative to base cases using organic solvent-borne coatings. In one base case
a solvent-borne coating spray method was used and in another base case a solvent-
borne coating dip method was used.
The two model lines discussed in this chapter are; a line with a yearly output
of 333,333 metal shelves, spray coated, and another line with a yearly output of
2,496,000 metal shelves dip coated. The 333,333 metal shelves represent a yearly
coated surface area of 3,000,000 square feet (278,707 square meters), the 2,496,000
metal shelves represent 22,464,000 square feet of coated area.
It was assumed for all cases that the coating lines for metal shelves were
operating 1920 hours per year (240 days, 1 shift).
It is the task of this chapter to select a realistic .number of alternative
emission control systems in order to analyze the range of environmental (Chapter 7)
and economic (Chapter 8) impacts associated with various alternative controls. For
this reason, several of the most viable of the various alternatives have been selected
for further consideration. These are presented - in order of decreasing emission
reduction -in Table 6-1 for the smaller line producing 333,333 metal shelves per
annum, and in Table 6-2 for the line with an output of 2,496,000 metal shelves per
year.
6-1
-------
Table 6-1. METAL FURNITURE EMISSION CONTROL SYSTEMS
Size of Line: 3,000,000 Square Feet Coated Area Per Year
Process
Powder coating, electrostatic spray
Conventional solvent-borne coating,
electrostatic spray
Carbon adsorber on spray booth,
and incinerator on cure oven (in-
cinerator with primary heat re-
covery)
High solids coating, electrostatic spray
Water-borne coating, electrostatic spray
Conventional solvent-borne coating
electrostatic spray
Carbon adsorber on spray booth
Incinerator on cure oven
(with primary heat recovery)
No control (base case)
Alternative
(Case)
Number
A-5
a
A-3
A-2
A-l
Solvent
Emitted
Metric
Tons/Year
5.5
13.2
17.1
Reduction
Percent
95-991
a
A-7"
A-4
A-6
1.7
2.8
3.6
90
83
79
68
22
0
a
With the add-on controls it was assumed that all the solvents emitted
from the application areas and flash-off and ovens went through the control unit.
For practical purposes, emission can be considered as zero; however,
minute emissions can be caused (0.5 to 3.0 percent) by plasticizers from
vinyl materials, and by curing agents used in conjunction with thermo-
setting type resins.
This is actually a combination of A-2 and A-3.
6-2
-------
With the add-on controls it was assumed that all the solvents emitted
from application areas and ovens went through the control unit. Most water wash
spray booths have recirculating water systems. Any solvent from overspray that is
34
captured by the water curtain is eventually evaporated into the air exhaust system .
Both incinerators and carbon adsorbers were figured as operating at an average
efficiency of 90 percent.
Table 6-2. METAL FURNITURE EMISSION CONTROL SYSTEMS
Size of Line: 22,464,000 Square Feet coated Area Per Year
Process
Water-borne electrodeposition
Solvent-borne dip coating with carbon
adsorber on dip tank, and incinerator
on cure oven
Water-borne dip coating
Solvent-borne dip coating
Carbon adsorber on dip tank
Incinerator on cure oven
(with primary heat recovery)
No control (base case)
Solvent
Alternative
(Case)
Number
B-2
B-5
B-6
B-3
B-4
B-l
Solvent
Emitted*
Metric
Tons/Year
6.24
9.18
18.40
42.23
58.75
91.80
Reduction
Percent
93
90
80
54
36
0
a
a
With the add-on controls it was assumed that all the solvents emitted
from the application areas and flash-off and ovens went through the con-
trol unit.
This is actually a combination of B-3 and B-4.
6-3
-------
The decreased emissions and percent reduction are from the base cases (A-l
and B-l respectively), which are uncontrolled organic solvent-borne coating systems.
6.1. ALTERNATIVE A-2
In this system, emissions from the curing oven of the model line (which
amount to only about 20 to 30 percent of the total emissions) are discharged to an
incinerator. Incineration is a process where compounds are combusted and reduced to
other compounds. Organic solvents used in the industrial finishing industry, in
general, can be converted by the incinerator into carbon dioxide and water vapor.
Incineration is the most universally accepted technique for reducing solvent
emissions from industrial processes. The value of this technology has been
1234
demonstrated in the can manufacturing industry ' ' ' , in the coil coating in-
56789 10 11
dustry ' ' ' ' and the automotive industry ' , etc.
By discharging the emissions of the curing oven to an incinerator, the
emissions of the model line A-l can be reduced to 13.2 metric tons per year - a
reduction of 22 percent.
A flow diagram of this system is shown in Figure 6-1.
6.2. ALTERNATIVE A-3
Activated carbon gained some attention mostly in the paper and fabric
coating industry for the removal of organic compounds from gaseous streams by
adsorption12'13'14'15.
In alternative system A-3, emissions from the spray booth and flash-off of the
model line (which amount to about 70 to 80 percent of the total emissions and flash-
off) are discharged to a carbon adsorption unit. A flow diagram of this system is
presented in Figure 6-2.
By the use of this technology, the emissions of the model line are reduced
from 17.1 metric tons per year to 2.8 tons - a reduction of 68 percent.
6.3. ALTERNATIVE A-4
In this alternative, the conventional solvent-borne paint is replaced with a
high solids coating material. Otherwise, the process is identical with the base case
(A-l). Due to the high solids content of the coating composition (therefore, low
solvent content) the emissions are reduced.
6-4
-------
Figure 6- 1. FLOW DIAGRAM - ALTERNATIVE A-2
APPLICATION OF SOLVENT-BORNE COATING BY ELECTROSTATIC SPRAY
BASE CASE WITH INCINERATOR ON OVEN
Stack
Overspray
(Solvent)
Ware
Paint,
Spray Booth
Thinner
Stack
Solvent Emission
Flashoff
of
Solvents
Overspray
(Solids and Organic Solvent)
Stack
I
Incinerator
90 Percent
Efficient
Evaporation Loss
(Solvent)
Cure
Oven
Coated
Product
-------
Figure 6- 2 . FLOW DIAGRAM - ALTERNATIVE A-3
APPLICATION OF SOLVENT-BORNE COATING BY ELECTROSTATIC SPRAY
BASE CASE WITH CARBON ADSORBER ON SPRAY BOOTH
Ware-
Paint,
Thinner
Stack
I
Carbon Adsorber
90 Percent
Efficient
Evaporation
(Solvent)
Spray Booth
J
Stack
Solvent Emission
Flashoff
of
Solvents
Evaporation
(Solvent)
Cure
Oven
Coated
Product
Overspray
(Solids and Organic Solvent)
-------
High solids coatings are currently investigated in the coating industry,
(including the metal furniture industry, for the reasons of energy savings and pollution
control)16'17.
By the use of high solids coating material, the emission of the model line (A-
1) can be reduced from 17.1 metric tons per year to 2.8 tons - a reduction of 83
percent.
A flow diagram of this process (see base case) is shown in Figure 6-3.
6.4. ALTERNATIVE A-5
In this alternative the solvent-borne coating material is replaced on the
model line by powder coating. The reduction is 95 to 99 percent with a minimum emis-
sion (minute emissions can be caused by plasticizers from vinyl materials, and by
some of the curing agents used in conjunction with thermosetting resins).
Of the control techniques presently in use in the metal furniture finishing
18 19 20 21 22 23 24
industry, powder coating is the most common '''' »*"»*' on outdoor and
institutional furniture. Also, other coating industries, like the automobile industry
25
investigate this technology on large scale production .
A flow diagram of this process is shown in Figure 6-4.
6.5. ALTERNATIVE B-2
Of the control techniques presently in use in the metal furniture industry,
water-borne coatings are in widespread use. Most of the water-borne coatings are
applied by electrodeposition (EDP)26.27,28,29,30,31,32,33<
Changing from an uncontrolled organic solvent-borne coat to an EDP system
for the metal furniture model line (base case or case B-l) would reduce the solvent
emissions from 91.8 metric tons per year to 6.24 tons - a reduction of 93 percent.
A typical electrodeposition system diagram is shown in Figure 4-4 of Chapter
4. A simplified flow diagram of this system is presented in Figure 6-5.
6-7
-------
Figure 6- 3. FLOW DIAGRAM - BASE CASE, ALTERNATIVES A-4 AND A-6
APPLICATION OF COATING BY ELECTROSTATIC SPRAY CONVENTIONAL (BASE CASE),
OR HIGH SOLIDS (A-4) SOLVENT-BORNE COATINGS OR WATER-BORNE COATINGS (A-6)
01
CO
st
Ware ^ Spray
Paint, 1
Thinner
ick St
Evaporation
(Solvent)
Flas
ack
Solvent Emission
hoff
»f
/ents
Overspray
(Solids and Solvent)
Sta
i
ck
Evaporation
(Solvent)
Cure (
Oven ^ 1
Coated
Product
-------
Figure 6- 4 . FLOW DIAGRAM - ALTERNATIVE A-5
APPLICATION OF POWDER COATING - ELECTROSTATIC SPRAY
en
to
Ware
Booth to Apply
Electrostatic
Powder Spray
Powder
I
Cure
Oven
Coated Product
Overspray
(Solids)
-------
Figure 6-5. FLOW DIAGRAM - ALTERNATIVE B-2
APPLICATION OF WATER-BORNE COATING BY ELECTRODEPOSITION (EDP)
Stack
Stack
Stack
I—'
o
Ware
EDP Coating
1
i
Transfer Loss
(Solvent)
EDP Dip Tank
•
*
Rinse
Solvent Loss
1 Evaporation Loss
1 (Solvent, Water)
Cure
Oven
^ Coated
Product
*Lose solvents into the sewer through
purging the ultrafiltrate liquid residue
-------
6.6. ALTERNATIVE B-3
Activated carbon is used in paper and fabric coating industries for the
removal of organic compounds from gaseous streams by adsorption. Applications
include recovery of solvent from various industrial operations, including industrial
finishing operations (see Chapter 4 and also the references listed under A-3).
In this system, emissions (which amount to approximately 50 percent of the
line) from the dip tank and flash-off of the model line are discharged to a carbon
adsorption unit. A flow diagram is shown in Figure 6-6.
This control system reduces dip tank emissions of the metal furniture model
line (B-l) from 91.8 metric tons per year to 42.23 metric tons - a reduction of 54
percent.
6.7. ALTERNATIVE B-4
In this system, emissions from the curing oven of the model line (which
amount to about 40 to 50 percent of the total line emissions) are discharged to an
incinerator. Incineration process was already discussed under alternative A-2.
Therefore, no details are discussed here.
By discharging the emissions of the curing oven to an incinerator, the
emissions of the model line B-l can be reduced to 58.75 metric tons per year - a
reduction of 36 percent.
A flow diagram illustrating this system is shown in Figure 6-7.
6.8. ALTERNATIVE B-5
This alternative is actually a combination of alternatives B-3 and B-4: the
emissions from the dip tank and flash-off are discharged to a carbon adsorption unit,
and the emissions of the curing oven are chanelled to an incinerator. This combined
carbon adsorber/incinerator system reduces total emissions from the model line (B-l)
to 9.18 metric tons per year - a reduction of 90 percent.
6.9. ALTERNATIVE B-6
In this system, the solvent-borne dip coating material is replaced by a water-
borne composition. By this, the emissions of the model line B-l can be reduced to
18.4 metric tons per year - a reduction of 80 percent.
6-11
-------
Figure 6-6. FLOW DIAGRAM - ALTERNATIVE B-3
APPLICATION OF SOLVENT-BORNE DIP COATING
BASE CASE WITH CARBON ADSORBER ON DIP TANK
Stack
to
Ware
Paint,
Thinner
t
Carbon Adsorber
90 Percent
Efficient
Stack
Evaporation
(Solvent)
Dip Tank
J
Solvent Emission
Flashoff
of
Solvents
Evaporation
(Solvent)
Cure
Oven
Coated
Product
-------
Figure 6-7. FLOW DIAGRAM - ALTERNATIVE B-4
APPLICATION OF SOLVENT-BORNE DIP COATING
BASE CASE WITH INCINERATOR ON OVEN
Stack
Stack
Ware
Paint,
Thinner
Evaporation
(Solvent)
Dip Tank
J
Solvent Emission
Flashoff
of
Solvents
Stack
Incinerator
90 Percent
Efficient
Evaporation Loss
(Solvent)
Cure
Oven
Coated
Product
-------
6.10. REFERENCES
1. Gabris, T. Springborn Laboratories, Inc. (formerly DeBell <5c Richardson,
Inc.). Trip Report 5. December 2, 1975.
2. Gabris, T. Springborn Laboratories, Inc. Enfield, Connecticut. Trip Report
6. December 2, 1975.
3. Gabris, T. Springborn Laboratories, Inc. Enfield, Connecticut. Trip Report
80. February 24, 1976.
4. Gabris, T. Springborn Laboratories, Inc. Enfield, Connecticut. Trip Report
128. March 24, 1976.
5. Gabris, T. Springborn Laboratories, Inc. Enfield, Connecticut. Trip Report
16. December 18, 1975.
6. Fisher, R. Springborn Laboratories, Inc. Enfield, Connecticut. Trip Report
27. December 12, 1975
7. Fisher, R. Springborn Laboratories, Inc. Enfield, Connecticut. Trip Report
31. December 12, 1975
8. Gabris, T. Springborn Laboratories, Inc. Enfield, Connecticut. Trip Report
35. January 8, 1976.
9. Gabris, T. Springborn Laboratories, Inc. Enfield, Connecticut. Trip Report
76. February 9, 1976.
10. Gabris, T. Springborn Laboratories, Inc. Enfield, Connecticut. Trip Report
112. March 12, 1976.
11. Gabris, T. Springborn Laboratories, Inc. Enfield, Connecticut. Trip Report
120. March 12,1976.
12. Gabris, T. Springborn Laboratories, Inc. Enfield, Connecticut. Trip Report
89. February 27, 1976.
13. Oge, M. Springborn Laboratories, Inc. Enfield, Connecticut. Trip Report
139. July 19, 1976.
14. Oge, M. Springborn Laboratories, Inc. Enfield, Connecticut. Trip Report
140. July 20, 1976.
15. Oge, M. Springborn Laboratories, Inc. Enfield, Connecticut. Trip Report
141. July 21, 1976.
16. Oge, M. Springborn Laboratories, Inc. Enfield, Connecticut. Trip Report
41. January 14, 1976.
17. Gabris, T. Springborn Laboratories, Inc. Enfield, Connecticut. Trip Report
36. January 16, 1976.
6-14
-------
18. Schrantz, J. Automatic powder systems coat lawn furniture. Industrial
Finishing. April 1975, pp 32-38.
19. Oge, M. Springborn Laboratories, Inc. Enfield, Connecticut. Trip Report
86. February 25, 1976.
20. Oge, M. Springborn Laboratories, Inc. Enfield, Connecticut. Trip Report
57. December 10, 1975.
21. Oge, M. Springborn Laboratories, Inc. Enfield, Connecticut. Trip Report
108. March 8,1976.
22. Oge, M. Springborn Laboratories, Inc. Enfield, Connecticut. Trip Report
72. February 4,1976.
23. Oge, M. Springborn Laboratories, Inc. Enfield, Connecticut. Trip Report
85. February 25, 1976.
24. Oge, M. Springborn Laboratories, Inc. Enfield, Connecticut. Trip Report
100. March 23, 1976.
25. Gabris, T. Springborn Laboratories, Inc. Enfield, Connecticut. Trip Report
38. January 15, 1976.
26. Oge, M. Springborn Laboratories, Inc. Enfield, Connecticut. Trip Report
103. March 9,1976.
27= Gabris, T. Springborn Laboratories, Inc. Enfield, Connecticut, Trip Report
9. December 9, 1975.
28. Gabris, T. Springborn Laboratories, Inc. Enfield, Connecticut. Trip Report
102. March 10, 1976.
29. Gabris, T. Springborn Laboratories, Inc. Enfield, Connecticut. Trip Report
110. March 11, 1976.
30. Gabris, T. Springborn Laboratories, Inc. Enfield, Connecticut. Trip Report
112. March 12, 1976.
31. Gabris, T. Springborn Laboratories, Inc. Enfield, Connecticut. Trip Report
120. March 12, 1976.
32. Gabris, T. Springborn Laboratories, Inc. Enfield, Connecticut. Trip Report
13. December 12, 1975.
33. Gabris, T. Springborn Laboratories, Inc. Enfield, Connecticut. Trip Report
73. February 10, 1976.
34. Holley, W.H. Springborn Laboratories, Inc. Enfield, Connecticut. Telephone
conversation with Binks Manufacturing Co., New Jersey, November?, 1977
6-15
-------
7. ENVIRONMENTAL IMPACT
7.1. AIR POLLUTION IMPACT
Metal furniture manufacturing lines are sources of organic solvent emissions.
The bulk of these emissions is due to the solvent-borne coating materials used to
protect and decorate the low carbon steel sheets, strips and tubings used in the
manufacture of the furniture.
Coatings for metal furniture must resist abrasion scuffing and maintain good
appearance. Institutional furniture is subjected to a more abusive environment and in
addition must withstand regular cleaning with alkali type cleansers.
Presently, the metal furniture industry employs mostly organic solvent-borne
coatings for spray, dip and flow coating processes. However, different techniques are
available today for reducing organic solvent emissions from metal furniture coating
facilities.
As an example for the use of conventional organic solvent-borne coating
material, the following figures are of interest. A metal furniture line producing
22,464,000 square feet coated area per year, and applying said coating material by dip
coating, causes an uncontrolled emission of approximately 92 metric tons per year. A
line producing 3,000,000 square feet of coated areas per year, and using the
electrostatic spray technique to apply the coating material, causes an uncontrolled
emission of approximately 17 metric tons per year.
In 1973 (a very high production year), United States consumption of solvents
1 2
in paints and coatings was 1,902,273 metric tons or 4,185,000,000 pounds ' . From
these 4,185 million pounds, 805 million were used directly in the manufacture of the
coating materials, while 1,365 million pounds of solvents were used as thinners and
2
for some other miscellaneous uses .
In 1973, the metal furniture industry (including fixtures) consumed 71,136
2
metric tons or 156.5 million pounds of organic solvents . These 156.5 million pounds
2
of organic solvents were used with 79.4 million pounds of resins and 56 million
o
pounds of pigments to make coating materials. Thus, the total paint consumption of
the metal furniture (and fixtures) industry in 1973 must have been 291.9 million
pounds or 132,681 metric tons (a total of the solvent, resins and pigment
consumption).
7-1
-------
If we examine these figures, the average organic solvent content as computed
is 54 percent by weight or 36 percent by volume. (We used 35 percent by volume for
our base case).
o
According to a recent survey of the National Paint and Coating Association ,
the metal furniture (and fixture) industry consumed 116 million pounds of organic
solvents in 1975. The 116 million pounds exclude thinners. The survey also states
that the solvent/resin weight ratio of these coating materials was 1.8.
It is also apparent from said survey that thinner and miscellaneous solvents
accounted to 32 percent of total solvents consumed. According to this, the total
solvent consumption of the 1975 metal furniture industry must have been close to 170
million pounds.
Based on the earlier cited solvent/resin weight ratio of 1.8, the 170 million
pounds of solvent should have required some 94 million pounds of resin as
compounding ingredients. Based on the 1973 consumption figures of the metal
o
furniture industry , the pigment/resin ratio was 0.7. This ratio is now used for
estimating the 1975 consumption.
In view of the above, the 1975 consumption of the metal furniture industry is
estimated as follows:
Millions Percent by Percent by
of Pounds Weight Volume
Organic
Solvent 170 52 62
Resin 94 28 > 38
Pigment 66 20 J included in resin
Total 330 100 100
The estimates for 1976, our base year for this study, are discussed under 7.1.2.3.
Estimated Hydrocarbon Emission Reduction in Future Years.
7-2
-------
The objectives of New Source Performance Standards are to limit the
emission of organics by imposing standards which reflect the degree of emission
reduction achievable through the application of the best adequately demonstrated
system(s) of emission reduction, taking into consideration the cost of achieving such
reduction. Several alternative organic solvent emission control systems (hereinafter
referred to as "Alternative") have been identified as candidates for the best system of
emission reduction.
In assessing the environmental impact and the degree of emission control
achieved by each alternative which could serve as the basis for standards, these
alternatives need to be compared. Also, other facets of environmental impact -such
as potential water pollution and solid waste generation - needed to be assessed.
Similarly, state regulations and controlled emissions should be considered. These are
discussed in the following sections.
7.1.1. State Regulations and Controlled Emissions
In August of 1971, Los Angeles County in California adopted Rule 66, Section
C, specifying that effective August 31, 1974, the maximum allowable organic
nonphotochemical emissions per paint facility was to be 3,000 pounds per day. The
rule allows only 40 pounds per day from sources using photoehemically reactive
solvent and 15 pounds per day from ovens. Emissions beyond this limit would require
control.
The regulations also provided an exemption for water-borne coatings where
the volatile content consists of 80 percent water and the organic solvent was a non-
photochemically reactive solvent.
There are very few coating users other than automobile and some truck
assembly plants which could consume enough coating product to aggregate 3,000
pounds of total organic solvent emission in a day. This is the reason why the Air
Resources Board of the State of California scheduled some consultation meetings for
4
October 1976 to gather information for developing a model rule to limit emissions of
volatile organic compounds from automotive coating operations.
7-3
-------
Based on preliminary discussions with coating manufacturers, the Organic
Solvent Regulation Study Group, composed of staff members of the California Air
Resources Board and several local Air Pollution Control Districts has developed for
discussion purposes, the following organic solvent content limits to be effective by
October 1, 1980:
Maximum Organic
Solvent Content
As Applied
Coating Use (by Volume)
Original Equipment Manufacture
Undercoats
(primer, primer-surfacer, sealer, etc.) 30%
Top coat
(by October 1, 1980) 37.5%
(by October 1, 1982) 30%
Final Repair
Metallic Color 55%
Solid Color 45%
These specifications are proposed for automotive coating lines only. However,
this thinking could serve as the guide line for the other industries.
Today only thirteen states have statewide regulations covering hydrocarbon
emissions. Approximately half of these states have regulations that are the same as,
or similar to, Rule 66 of Los Angeles. Such standards carefully limit the amount of
photochemically reactive (PCR) solvent volatiles which may be emitted within a
given time period from both baking ovens and curing operations and from coating
applications in any plant.
There are difficulties in understanding and interpreting Rule 66. While many
states have Rule 66 regulations, many have variations such as no maximum limit per
day. Even those states that have the same regulation seem to interpret it differently.
The interpretation of the definition of the affected facility has a great impact on the
stringency of the standard. The situation is complicated even more by the current
activity in rewriting state regulations.
As to stringency, the Connecticut regulation is the most stringent in terms of
total daily organic solvent emission restrictions. The oven discharges of organic
materials are limited to 15 pounds per day, unless the discharge of the oven has been
reduced by at least 85 percent.
7-4
-------
There are ten states in which state regulations are in force in designated
counties only. There twenty-two states where no hydrocarbon emission controls are
required on stationary sources. And, there are five states in which state regulations
are in the process of formulation.
7.1.2. Uncontrolled and Controlled Emissions (Alternatives)
The objective of this chapter is to discuss and determine what control methods
coupled with which processes will allow substantial reductions in solvent emissions
over the base line situation without an extreme adverse effect on secondary pollution
such as water and solid waste. This chapter should help to identify those control
methods/processes which can result in significant emission reduction and should guide
the selecting of candidates for NSPS.
7.1.2.1. Spray Coating
For our base case, we have assumed that the coating line, which produces
metal shelves, has a yearly output of 3 million square feet coated area. It was also
assumed that the coating line was operating 1920 hours per year by being on one shift
(8-hour shift, 240 work days per year). The base case is representative of what might
be found in the industry. This model line is using traditional organic solvent-borne
finishes.
Our base case indicates that the uncontrolled organic solvent-borne coating
operation results in a yearly emission of 17.1 metric tons (37,620 pounds). This
translates into 157 pounds per day.
The following alternatives represent control technologies that could be used to
reduce the emission of volatile organic solvents. Typical emissions from such
alternative lines have been discussed and have been compared against the base case.
With the add-on controls it was assumed that all the solvents emitted from the
application areas and ovens went through the control unit.
(1) Incinerator on Cure Oven
Alternative A-2 (Table 7-1)
In this case an incinerator is treating the emissions from the cure oven (which
amount to about 25 percent of the total line emissions) of the model line, which can
reduce the yearly emission (17.1 metric tons) by 22 percent, yielding a yearly
emission of 13.2 tons or 29,040 pounds. Converting this into daily emissions, the
result is 121 pounds per day.
(2) Carbon Adsorber on Spray Booth and Flash-off
Alternative A-3 (Table 7-1)
7-5
-------
In this Alternative a carbon adsorber is put on the spray booth and flash-off
area of the model line. A reduction of 68 percent in emission is observed, bringing
the 17.1 metric tons of emission down to 5.5 tons. This amounts to 50 pounds per day.
(3) High Solids Coating
Alternative A-4 (Table 7-1)
In this Alternative, the conventional solvent-borne paint is replaced
with a high solids coating material. Due to the high solids content of the coating
composition (therefore, low solvent content) the emissions are reduced by 83 percent,
yielding a yearly emission of 2.8 metric tons or 25 pounds per day.
(4) Powder Coating
Alternative A-5 (Table 7-1)
In this Alternative the solvent-borne coating material is replaced on the
model line by powder coat. The reduction is 95 to 99 percent with an emission of 1 to
5 percent.
(5) Water-Borne Coating
Alternative A-6 (Table 7-1)
In this example, a water-borne coating material is substituted for the
solvent-borne coating. This Alternative reduces the emission by 79 percent to 3.6
metric tons per year, or 33 pounds per day.
(6) Carbon Adsorber on Spray Booth and Flash-off
and Incinerator on Cure Oven
Alternative A-7 (Table 7-1)
This is a combination of Alternatives A-2 and A-3. The reduction is 90
percent (22 percent for A-2 and 68 percent for A-3 or 90 percent total). The
emissions are reduced from the uncontrolled 17.1 metric tons to 1.7 tons. Converting
this into daily emissions, the model line has an emission of 16 pounds per day.
7.1.2.2. Dip Coating
For our base case, we have assumed that the coating line has a yearly output
of 22,464,000 square feet coated area. Similarly to the spray coating line (7.1.2.1),
the line operates on one (8-hour) shift, 240 days per year. This amounts to 1920 work
hours per annum.
7-6
-------
Table 7-1. METAL FURNITURE PAINTING OPERATION
SPRAY COATING HYDROCARBON EMISSION FACTORS AND
CONTROLLED AND UNCONTROLLED MODEL PLANTS
Percent
Model Plant Alternative Tons/Year Reduction
Uncontrolled (A-l) 17.1 (19.2)
Controlled
Incinerator on cure oven A-2 13.2 (14.5) 22
Carbon adsorber on spray booth A-3 5.5 ( 6.0) 68
High solids coating A-4 2.8 ( 3.0) 83
Powder coating A-5 Ob 95 - 99
Water-borne coating A-6 3.6 ( 3.9) 79
Carbon adsorber on spray
booth and flash-off and in-
cinerator on cure oven A-7 1.7(1.9) 90
a Units are metric tons; U.S. tons shown in parentheses. With add-on controls
it was assumed that all the solvents emitted from the application areas and
ovens went through the control unit.
For practical purposes, emission can be considered as zero; however, minute
emissions (0.5 to 3.0 percent) can be caused by plasticizers from vinyl materials
and by curing agents used in conjunction with thermosetting type resins.
7-7
-------
Our base case (B-l) indicates that the uncontrolled organic solvent-borne
coating operation results in a yearly emission of 91.8 metric tons (201,960 pounds).
This amounts to 841 pounds per day.
The following alternatives represent control technologies that could be used to
reduce the emission of this line. Typical emissions from such alternative lines are
compared against the base case and presented in Table 7-2.
(1) Water-Borne - Electrodeposition
Alternative B-2 (Table 7-2)
In this Alternative, a water-borne coating material is applied by
electrostatic deposition. By using this technology, the emission of the line is reduced
by 93 percent. Thus, from the 91.8 metric tons of yearly emission to 6.24 tons. This
amounts to 57 pounds per day. (The uncontrolled line produces an emission of 841
pounds per day).
(2) Carbon Adsorber on Dip Tank and Flash-off
Alternative B-3 (Table 7-2)
In this system, emissions from the dip tank of the model line are
discharged to a carbon adsorber unit. Emissions of the line are reduced by 54
percent, or to 42.2 metric tons per year. This corresponds to 387 pounds per day.
(3) Incinerator on Cure Oven
Alternative B-4 (Table 7-2)
In this example, an incinerator is treating the emissions from the cure
oven (approximately 40 percent of the total line) of the model line. This can reduce
the emission by 36 percent. Thus the yearly emissions are reduced to 58.75 metric
tons, or 538 pounds per day.
(4) Carbon Adsorber on Dip Tank and Flash-off
and Incinerator on Cure Oven
Alternative B-5 (Table 7-2)
This is a combination of Alternatives B-3 and Alternative B-4. The
achievable emission reduction is 90 percent. The yearly emission of the line is
reduced to 9.1 metric tons, or 83 pounds per day.
(5) Water-Borne Dip Coating
Alternative B-6 (Table 7-2)
A water-borne coating material is replacing the solvent-borne material in the
dip tank. The achievable emission reduction is 80 percent. The yearly emission of
the line is reduced to 18.4 metric tons, or 168 pounds per day.
7-8
-------
Table 7-2. METAL FURNITURE PAINTING OPERATION
DIP COATING HYDROCARBON EMISSION FACTORS AND CONTROL EFFICIENCY
CONTROLLED AND UNCONTROLLED MODEL PLANTS
Percent
Model Plant Alternative Tons/Year Reduction
Uncontrolled (B-l) 91.8 (100.9)
Controlled
Water-borne - electrodeposition B-2 6.2 ( 6.8) 93
Solvent-borne dip coating
Carbon adsorber on dip tank B-3 42.2 ( 46.4) 54
Incinerator on cure oven
and flash-off B-4 58.7 ( 64.6) 36
Carbon adsorber on dip tank
and incinerator on cure oven B-5 9.1 ( 10.0) 90
Water-borne dip coating B-6 18.4 ( 20.2) 80
a Units are metric tons; U.S. tons shown in parentheses.
With the add-on controls it was assumed that all the solvents emitted from the
application areas and ovens went through the control unit.
7-9
-------
7.1.2.3. Estimated Hydrocarbon Emission Reduction in Future Years
The household furniture industry from 1973 to 1980 is expected to grow at an
annual rate of 2.4 percent . Other branches of the furniture industry, like office
metal furniture, public building furniture, and metal partitions and fixtures, expect to
grow at a rate of 4.4 percent . Growth rates predicted for the period of 1980 to 1985
are 3.9 percent for household furniture , and 3.0 percent per annum for other
furniture .
Employment statistics, and sales projections presented in Chapter 3, indicate
that approximately 30 percent of the total furniture industry is constituted by
household furniture. The remaining 70 percent are made up from furniture sold to
offices, public buildings, and sold as partitions and fixtures. Since the predicted
growth rates for these industries are not significantly different, it is reasonable to
take proportional averages for our work.
In view of the above, the metal furniture industry in the period of 1973 to 1980
is expected to grow at a rate of 3.8 percent per year (0.3 times 2.4 plus 0.7 times
4.4), and from 1980 to 1985, at an average rate of 3.3 percent.
We have estimated (see earlier pages of this chapter) that the solvent
consumption of the metal furniture industry in 1975 was 170 million pounds (77,272
metric tons). Based on this figure, and the discussed estimated growth rates, the
hypothetical emissions from uncontrolled metal furniture coating operations in the
United States are estimated under A-l in the tables which follow.
The adoption by the metal furniture industry of programs for the reduction of
emissions is a long-range consideration. In 1973, from the 79.4 million pounds of
resins consumed by the metal furniture industry, only 2 percent was used of new
technology coating materials: 0.5 million pounds in water-borne, and 1.1 million
o
pounds in powder coats .
Six control options for spray coating, and five options for dip coating are
available to the industry to control emissions over a projected growth period up to the
year 1985. Tables 7-3 and 7-4 encompasses the effectiveness of alternate control
options on the reduction of annual emissions assuming that each year 5 percent of the
industry would be affected by the use of pollution control systems. Tables 7-5 and 7-
6 show the effectiveness at 10 percent yearly penetration.
7-10
-------
Table 7-3. COMPARATIVE EFFECTIVENESS OF ALTERNATE CONTROL SYSTEMS
EXPRESSED IN ANNUAL ORGANIC EMISSIONS
CONTROLS ON A SPRAY COATING OPERATION
ASSUMED ANNUAL PENETRATION: 5 PERCENT
Emissions, Metric Tons/Year
Year
1976
1977
1978
1979
1980
1981
1982
1983
1984
1985
A-l
Uncontrolled
Emissions
80,208
83,256
86,420
89,704
93,113
96,186
99,360
102,639
106,026
109,525
A-2
Incinerator
on Cure Oven
80,208
82,339
84,518
86,742
89,016
90,894
92,802
94,734
96,694
98,681
A-3
Carbon Adsorber
on Spray Booth
and Flash-off
80,208
80,425
80,543
80,553
80,449
79,834
79,090
78,210
77,186
76,009
A-4
High Solids
Coating
80,208
79,800
79,247
78,535
77,655
76,226
74,619
72,882
70,824
68,616
A-5
Powder
Coating
80,208
79,093
77,778
76,248
74,490
72,139
69,552
66,715
63,615
60,238
A-6
Water-Borne
Coating
80,208
79,967
79,593
79,073
78,400
77,188
75,811
74,259
72,521
70,588
A-7
Carbon Adsorber
on Spray Booth
_ and Flash-off
Incinerator on Oven
80,208
79,509
78,642
77,593
76,352
74,543
72,532
70,307
67,856
65,166
-------
Table 7-4. COMPARATIVE EFFECTIVENESS OF ALTERNATE CONTROL SYSTEMS EXPRESSED
IN ANNUAL ORGANIC EMISSIONS CONTROLS ON A DIP COATING OPERATION
ASSUMED ANNUAL PENETRATION: 5 PERCENT
Emissions, Metric Tons/Year
B-l
B-2
B-3
Carbon Adsorber
B-4
B-5
Carbon Adsorber on
Dip Tank
B-6
Year
1976
1977
1978
1979
1980
1981
1982
1983
1984
1985
Uncontrolled
Emissions
80,208
83,256
86,420
89,704
93,113
96,186
99,360
102,639
106,026
109,525
Water-Borne
Electrodeposition
80,208
79,384
78,383
77,190
75,793
73,822
71,638
69,229
66,584
63,688
on Dip Tank
and Flash-off
80,208
81,007
81,753
82,437
83,056
83,200
83,263
83,239
83,123
82,909
Incinerator
on Cure Oven
80,208
81,756
83,309
84,859
86,408
87,528
88,629
89,706
90,757
91,781
and Flash-off
Incinerator on Oven
80,208
79,509
78,642
77,593
76,352
74,543
72,532
70,307
67,856
65,166
Water-Borne
Dip Coat
80,208
79,925
79,506
78,939
78,214
76,948
75,513
73,899
72,097
70,095
-------
Table 7-5. COMPARATIVE EFFECTIVENESS OF ALTERNATE CONTROL SYSTEMS
EXPRESSED IN ANNUAL ORGANIC EMISSIONS
CONTROLS ON A SPRAY COATING OPERATION
ASSUMED ANNUAL PENETRATION: 10 PERCENT
Emissions, Metric Tons/Year
Year
1976
1977
1979
1981
1983
1985
A-l
Uncontrolled
Emissions
80,208
83,256
89,704
96,186
102,639
109,525
A-2
Incinerator
on Cure Oven
80,208
81,423
83,783
85,605
86,832
87,838
A-3
Carbon Adsorber
on Spray Booth
and Flash-off
80,208
77,602
71,404
63,482
53,783
42,495
A-4
High Solids
Coating
80,208
76,345
67,368
56,269
43,006
27,709
A-5
Powder
Coating
80,208
72,187
58,471
47,362
38,363
31,073
A-6
Water-Borne
Coating
80,208
76,678
68,444
58,192
45,880
31,652
A-7
Carbon Adsorber
on Spray Booth
and Flash-off
Incinerator on Oven
80,208
75,762
65,484
52,902
37,976
20,809
-------
Table 7-6. COMPARATIVE EFFECTIVENESS OF ALTERNATE CONTROL SYSTEMS EXPRESSED
IN ANNUAL ORGANIC EMISSIONS CONTROLS ON A DIP COATING OPERATION
ASSUMED ANNUAL PENETRATION: 10 PERCENT
Emissions, Metric Tons Per Year
Year
1976
1977
1979
1981
1983
1985
B-l
Uncontrolled
Emissions
80,208
83,256
89,704
96,186
102,639
109,525
B-2
Water-Borne
Electrodeposition
80,208
75,512
64,677
51,459
35,801
17,852
B-3
Carbon Adsorber
on Dip Tank
and Flash-off
80,208
78,759
75,172
70,216
63,841
56,295
B-4
Incinerator
on Cure Oven
80,208
80,258
80,016
78,872
76,774
74,038
B-5
Carbon Adsorber on
Dip Tank
and Flash-off
Incinerator on Oven
80,208
75,762
65,484
52,902
37,976
20,809
B-6
Water-Borne
Dip Coat
80,208
76,595
68,175
57,711
45,161
30,666
-------
Table 7-7. EFFECTIVENESS OF ALTERNATE CONTROL SYSTEMS - YEAR 1985
EXPRESSED IN ANNUAL ORGANIC EMISSIONS
CONTROLS ON A DIP COATING OPERATION
COMPARATIVE ANNUAL PENETRATION: 5 AND 10 PERCENT
Emissions, Metric Tons/Year
Control System
By Add-On Equipment
Carbon adsorber on dip tank
and flash-off
Incinerator on cure oven
Carbon adsorber on dip tank
and flash-off and incinera-
tor on cure oven
By Coating Composition
Alternative
Number Uncontrolled
a
B-3
B-4
B-5
Annual Annual
Penetration Penetration
5% 10%
109,525
109,525
109,525
82,909
91,781
65,166
56,295
74,038
20,809
Water-borne coating
electrodeposition
Water-borne dip coating
B-2
B-6
109,525
109,525
63,688
70,095
17,852
30,666
a
No add-on equipment with conventional solvent-borne coating material.
7-15
-------
Table 7-8. EFFECTIVENESS OF ALTERNATIVE CONTROL SYSTEMS - YEAR 1985
EXPRESSED IN ANNUAL ORGANIC EMISSIONS
CONTROLS ON A SPRAY COATING OPERATION
COMPARATIVE ANNUAL PENETRATION: 5 AND 10 PERCENT
Emissions, Metric Tons/Year
Control System
By Add-On Equipment
Incinerator on cure oven
Carbon adsorber on
spray booth and flash-off
Carbon adsorber on spray
booth and flash-off and
incinerator on cure oven
By Coating Composition
High solids coating
Powder coating
Water-borne coating
Alternative
Number Uncontrolled
a
A-7
A-4
A-5
A-6
Annual
Penetration
5%
A-2 109,525
A-3 109,525
109,525
109,525
109,525
109,525
65,166
68,616
60,238
70,588
Annual
Penetration
10%
98,681 87,838
76,009 42,495
20,809
27,709
31,073
31,652
No add-on equipment with conventional solvent-borne coating material
7-16
-------
7.2. WATER POLLUTION IMPACT
When solvent-borne coatings are applied by spraying, the spraying operation is
carried out in the spray booth. With the increased attention to air pollution, the
efficiency of particulate removal from the spray booth is of great importance to the
metal furniture coating lines. As a result, water-wash spray booths of advanced
design are coming into use. These booths have a grid in the floor through which the
overspray is drawn before being exhausted.
In a spray booth, typically used in the industrial finishing industry, 95 percent
of the paint participates are captured by the water curtain, but most of the solvent
escapes to the atmosphere, either up the stack due to evaporation from the water
>7
curtain, or as fugitive emissions by evaporation from the water collection tank . For
most paints used, the solvents are immiscible in the water which facilitates their
7
discharge into the air .
Water-borne electrodeposition coats are prepared by neutralizing highly
acidic polymers with an alkali (like amines) so that these polymers can be dissolved or
suspended in water. Small amounts of solvents are also added to increase the water
g
dispersibility .
In the coating process the paint solids coat the metal ware, leaving alkali
coalescing solvents behind in the tank. These products must be removed. In modern
installations, ultrafiltration is used to automatically remove the water-solubles and
chemical agents which are left behind during the process (see details in Section 7.3. -
Solid Waste Disposal).
If the effluent water originates from properly operating ultrafiltration only
and is treated properly, it can be adequately handled in municipal or in-house sewage
treatment facilities. On the other hand, if the electrocoating systems allows rinse
water and/or paint to drip or be spilled on the floor and the rinsing and clean-up
water is not automatically placed in a reservoir for treatment, this painting operation
could cause pollution.
Especially important in this instance is the matter of "dragout." At the end
of the coating operation the dipped ware becomes coated with an additional film of
adhering paint called dragout. This film is more porous than the plated coating;
therefore, it is usually rinsed off. Also, a dragout takes place as the ware leaves the
tank for the next location. This dragout is reclaimed through an ultrafiltration
system.
7-17
-------
Water-borne spray-coating materials, in the metal furniture industry, do not
represent demonstrated technology as yet. Nevertheless, water-borne coating
8 9 10
materials are used by spraying both in the automotive industry ' ' . and in the can
industry . Water-borne spray-coat materials, however, are made with water-
miscible solvents to assure good suspension of the resin binder in the water phase of
the coating material. These various water-miscible solvents (glycols, and certain
esters and alcohols) found in the water-borne coating materials are extremely
miscible with water wash and actually act as coupling agents between the suspended
particles and the water.
The problem with organic solvent in effluent water is the chemical oxygen
demand (COD). COD is not a pollutant in itself; it is a problem only if it is
discharged to a stream in sufficient concentration and quantity to deplete the oxygen
in the stream and thereby affect fish life and other water life.
There are no water pollution impacts associated with the other alternative
emission control systems; however, incineration or adsorption of spray booth exhaust
- although technically feasible - have not been used at any plant. As far as carbon
adsorption is concerned, it is to be noted that some solvents used in solvent-borne
coating systems are sufficiently water-miscible to pose a water pollution problem if
regeneration steam is condensed and discharged without being treated.
7.3. SOLID WASTE DISPOSAL IMPACT
Water-borne electrodeposition operations can have an impact on solid waste
disposal. In older installations the dragout and rinse were discarded, resulting in a
waste disposal problem. This also causes a paint loss. Improvements have been made,
however, to reduce paint cost through the inclusion of some means of reusing this
paint by returning it to the tank.
In modern operations, ultrafiltration is used to automatically remove the
amine(s), solvents, and water-solubles which are left behind during the electrocoating.
Consequently, it is possible to set up a completely closed system with practically no
waste problem.
Once a year there is a regular cleaning of the filter system. Otherwise
cleaning is not needed except on occasions such as, for example, when a paper cup or
other foreign object is accidently dropped into the tank. Such a minor cleaning job,
however, does not involve more paint than a few gallons.
7-18
-------
There are no serious solids waste disposal problems associated with
electrocoating. Sludge may develop in the tank, leading to a minor solid waste
disposal problem; however, sludge is generally a result of improperly controlled
chemistry of the electrocoating tank or poor housekeeping (such as allowing parts to
accumulate in the tank). In any case, the amount of such solid waste is not excessive.
While water-borne electrodeposition type coatings no longer present any
serious sludge and solid waste problems, water-borne spray coats are more prone to
do so. Water-borne spray coat materials, because they are partial or full suspension
systems just as are dispersions and/or emulsions, display considerably less mechanical
and storage stability than do organic solvent-borne topcoat materials, which are often
actually true solutions. In a dispersion, fine particles (of the binder) are suspended in
a continuous liquid phase, like water. In an emulsion the solids are liquified with the
help of solvent(s), and droplets of this are suspended in a continuous liquid phase like
water.
The stability of these suspension (also referred to as colloidal) systems is
much dependent on the water-to-sol vent ratio used. This is especially true when the
water-to-solvent ratio of the water-borne topcoat material is disturbed, as it is when
the overspray of the water-borne topcoat material hits the water wash. In the water
wash the major portion of the water-borne topcoat overspray is thrown out of
suspension, forming lumps consisting of agglomerated solids with locked-in water.
9 10
This can seriously increase the amount of sludge formed in a plant ' .
For example, an automobile plant reported that the sludge tank had to be
cleaned only once a year when using solvent-borne topcoats, and as the plant switched
12
to water-borne topcoats, the sludge tank had to be cleaned every three months .
As a result of the above situations - the water being filtered at and
recirculated from the sludge tanks to the spray booths of coating lines - the water
must contain significant amounts of water-miscible solvents as well as colloidal
particles of the coagulated binder and pigment. Particles which are of ultrafine size
are impossible to filter out by conventional filtering methods.
As to the exact amounts and compositions of the sludge, estimates of the
various industry spokesmen vary over a wide spectrum.
7-19
-------
There are some basic differences between the treatment of sludge from
solvent-based coatings and that of water-borne spray coating materials. Sludge from
water-based spray coat materials, in order to break the suspension system and to
remove the particles, is treated with slightly acidic compounds like calcium acetate
13
at an actual pH of 3-4 . Ultrafiltration could be used eventually to remove the
colloidal particles; but this method is labeled as an expensive approach to the
problem .
There is little solid waste impact associated with alternatives other than
water-borne coatings. In the case of carbon adsorption (because of the high cost of
the carbon), the carbon is returned to the supplier for regeneration. In the case of
powder coats (because of the high cost of the powder), the oversprayed powder is
recovered by means of cyclone(s) - with the possible additional help of tube or bag
filters. Virtually no solid by-product is produced by incineration.
7.4. ENERGY IMPACT
With the exception of high solids, powder and water-borne spray-coat systems
- all alternative emission control systems require some additional energy.
In contrast to the necessary exhausting method used for solvent-borne paint
systems, the exhaust from a powder coating application booth usually can be filtered
and returned to the room. This makes possible a considerable energy reduction -
attributable to less makeup air, less oven exhaust no flashoff zone, and the
14
elimination of heat-up zones in the oven .
The energy impact associated with each of the alternative emission control
systems outlined in Chapter 6 and discussed in this chapter is summarized in Tables 7-
9 and 7-10; these tables are a compact representation and summary of energy
balances prepared for the purpose of comparing the energy required for a base case
finishing model with the energy required when pollution reduction coatings or add-on
emission controls are utilized.
7-20
-------
Table 7-9. ENERGY BALANCE - ON A SPRAY COATING OPERATION
Energy Requirements Per Line
Model Description
Base case
Incinerator on cure
oven
Carbon adsorber on
spray booth and flash-off
High solids coating
Powder coating
Water-borne coating
Carbon adsorber on
spray booth and flash-
off and incinerator on
cure oven
Total Energy
Alternative
Number
A-l
A-2
f A-3
A-4
A-5
A-6
Electricity a
KWH/Year
192,000
203,500
306,600
192,000
192,000
230,400
Gasb
MCF/Year
3,840
6,048
3,820C
2,690
2,400
2,572
PerRYear
10° BTU
4,495
6,743
4,867
3,345
3,055
3,359
A-7
318,100
6,331
7,417
a
Conversion factor: KWH = 3,415 BTU
Conversion factor: 1 cubic foot = 1,000 BTU
Adjusted for energy credit (303 MCF/year) due to solvent recovery
7-21
-------
Table 7-10. ENERGY BALANCE ON A DIP COATING OPERATION
Energy Requirements Per Line
Model Description
a
Alternative Electricity Gas
Number KWH/Year MCF/Year 10" BTU
Total Energy
Per Year
Base Case B-l
Water-borne coating
electrodeposition B-2
Solvent-borne dip
coating -
Carbon adsorber on
dip tank and flash-off B-3
153,600
960,000
210,900
6,720
4,500
6,670
7,244
7,778
7,390
Incinerator on
cure oven
B-4
176,640 10,560
11,163
Carbon adsorber on
dip tank and flash-off
and incinerator on
cure oven B-5
233,940
11,320
12,119
Water-borne dip
coating
B-6
153,600
4,503
5,027
a
Conversion factor: KWH - 3,415 BTU
Conversion factor: 1 cubic foot = 1,000 BTU
Adjusted for energy credit (810 MCF/year) due to solvent recovery
7-22
-------
7.5. OTHER ENVIRONMENTAL IMPACTS
Electrodeposition (EDP) coatings contain amines that are driven off during
the curing step. Some plants have found it necessary to incinerate the oven exhaust
gas to eliminate the visible emission and mal odors associated with these amines ;
1 fi
some other plants have installed scrubbers for the same purpose .
No environmental impacts other than those discussed above are likely to arise
from standards of performance for metal furniture painting (coating) operations,
regardless of which alternative emission control system is selected as the basis for
standards.
7.6. OTHER ENVIRONMENTAL CONCERNS
7.6.1. Irreversible and Irretrievable Commitment of Resources
The alternative control systems will require the installation of additional
equipment, regardless of which alternative emission control system is selected. This
will require the additional use of steel and other resources. This commitment of
resources is small compared to the national usage of each resource. A good quantity
of these resources will ultimately be salvaged and recycled. With the exception of
carbon adsorption, there are not expected to be significant amounts of space (or land)
required for the installation of control equipment and/or new coating technology
because all control systems can be located with little additional space required.
Therefore, the commitment of land on which to locate additional control devices
and/or application equipment is expected to be minor.
The increase in the use of activated carbon is also expected to be
insignificant. In many cases the carbon can be regenerated and reused.
As can be noted, the use of primary and secondary heat recovery would
enhance the value of incineration; here it is reasoned that without heat recovery,
significant energy would be lost.
7.6.2. Environmental Impact of Delayed Standards
Delay of proposal of standards for the metal furniture industry will have
major negative environmental effects on emission of hydrocarbon to the atmosphere
and minor or no positive impacts on water and solid waste. Furthermore, there does
not appear to be any emerging emission control technology on the horizon that could
achieve greater emission reductions or result in lower costs than that represented by
7-23
-------
the emission control alternatives under consideration here. Consequently, delaying
standards to allow further technical developments appears to present no "trade-off"
of higher solvent emissions in the near future against lower emissions in the distant
future.
7.6.3. Environmental Impact of No Standards
Growth projections have been presented in earlier sections. It is obvious that
the increased production of metal furniture will add to the national solvent emissions.
There are essentially no adverse water and solid waste disposal impacts
associated with either of the alternative emission control systems proposed in this
chapter. Therefore, as in the case of delayed standards, there is no trade-off of
potentially adverse impacts in these areas against the negative result on air quality
which would be inherent with not setting standards.
7-24
-------
7.7 REFERENCES
1. Tess, Roy W. Chemistry and Technology of Solvents; Chapter 44 in Applied
Polymer Science. American Chemical Society, Organic Coatings and Plastics
Division. 1975.
2. Sources and Consumption of Chemical Raw Materials in Paints and Coatings -
by Type and End-Use. Stanford Research Institute. November 1974.
3. Bruce Ocko. Modern Paint and Coating Magazine. March 1977. p 61.
4. Air Resources Board, State of California, Sacramento, California 95812.
Ronald A. Friesen, Chief Industrial Project Evaluation and Control Strategy
Development Branch. Public Consultation Meeting on Methods to Reduce
Solvent Emissions from Automotive Coatings. Meeting announcement,
September 16, 1977.
5. Monthly Labor Review, U.S. Department of Labor. November 1976. p 5.
6. Jones, F.N. What Properties Can You Expect from Aqueous Solution Coatings.
SME Technical Paper, FC74-641:3-4, 1974.
7. Holley, William H. Springborn Laboratories, Inc. (formerly DeBell <5c
Richardson, Inc.) and Andreola, M., Binks Manufacturing Company. Telephone
conversation.
November 7, 1977.
8. Gabris, T. Springborn Laboratories, Inc. (formerly DeBell & Richardson, Inc.)
Trip Report 56. February 5, 1976
9. Gabris, T. Springborn Laboratories Inc. (formerly DeBell <5c Richardson, Inc.).
Trip Report 102. March 10, 1976.
10. Gabris, T. Springborn Laboratories, Inc. (formerly DeBell & Richardson, Inc.).
Trip Report 110. March 11, 1976.
11. Gabris, T. Springborn Laboratories, Inc. (formerly DeBell & Richardson, Inc.)
Trip Teport 5. December 2, 1975.
12. Gabris, T. Telephone conversation with one of the California General Motors
plants. October 29,1976.
13. Gabris, T. Telephone conversation with Gerwert, Phil. General Motors Water
Pollution Section. November 2, 1976.
14. Product Finishing. June 1976. p 166
15. Gabris, T. Springborn Laboratories, Inc. (formerly DeBell & Richardson, Inc.).
Trip Report 112. March 12, 1976.
16. Gabris, T. Springborn Laboratories, Inc. (formerly DeBell
-------
8. ECONOMIC IMPACT
8.1. INDUSTRY ECONOMIC PROFILE
8.1.1 Introduction
The metal furniture industry as defined here includes all establishments
engaged in the manufacture of metal household furniture.
1. Metal Household Furniture SIC 2514
2. Metal Office Furniture SIC 2522
3. Public Building and
Related Furniture SIC 2531
4. Metal Partitions and Fixtures SIC 2542
Major products in the metal household classification include indoor dining and
breakfast furniture, and porch, patio and outdoor seating and tables; main office
furniture products are chairs, desks, and filing and storage cabinets. Public building
and related furniture covers furnishings purchased by schools and institutions such as
hospitals. Room dividers, shelves, lockers and storage bins are classified under metal
partitions and fixtures.
8.1.2. Industry Size
Tables 8.1-1 through 8.1-5 present a time series of basic statistics on the indus-
try stretching from 1958 to 1975.a fables 8.1-1 through 8.1-4 include metal
household furniture, metal office furniture, public building and related furniture, and
metal partitions and fixtures, respectively. Table 8.1-5 presents total statistics for
the four classifications.
In 1975, the industry shipped products worth $3.4 billion, employing 71,400
production workers and 22,900 other employees. Production workers earned an
average annual salary of $8,209 in 1975 or $4.21 per hour for an average work week of
38 hours. Other employees earned an average annual wage of $13,332.
a Data for 1958 is not available for metal partitions and fixtures, until 1963 metal
and wood partitions and fixtures were classified as one industry.
8-1
-------
Table 8.1-1. BASIC INDUSTRY STATISTICS
METAL HOUSEHOLD FURNITURE
(SIC 2514)
oo
I
to
All Employees
Year
1975
1974
1973
1972
1971
1970
1969
1968
1967
1963
1958
Establish-
ments
(Number)
NA
NA
NA
467
NA
NA
NA
NA
486
517
626
Number
(Thousands)
28.1
35.4
36.9
34.4
31.5
32.4
32.8
32.1
31.0
29.3
30.3
Payroll
(Million
Dollars)
233.5
257.5
253.6
222.5
194.2
188.1
181.4
169.4
155.5
128.8
124.6
Production Workers
Number
(Thousands)
22.5
28.8
30.6
28.6
25.8
26.7
27.6
26.5
25.8
24.3
24.6
Man-Hours
(Millions)
41.5
53.8
58.9
53.7
49.7
50.4
52.4
51.2
50.3
47.9
48.2
Wages
(Million
Dollars)
155.4
176.9
177.9
157.6
133.7
131.3
132.6
120.5
109.6
92.0
89.2
Value
Added by
Manu-
facture
(Million
Dollars)
436.6
483.6
508.8
447.2
386.3
365.8
346.2
333.9
291.3
247.0
218.7
Cost of
Materials,
Fuel
(Million
Dollars)
478.2
529.4
506.6
452.4
380.4
360.7
352.8
333.2
312.0
280.7
274.7
Value of
Industry
Shipments
(Million
Dollars)
930.6
1,003.0
999.8
890.4
763.9
724.9
697.1
664.3
605.3
524.3
496.1
Gross
Capital Value of
Expendi- Fixed
tures, New Assets
(Million
Dollars)
14.7
18.2
25.5
16.9
10.8
13.8
12.9
10.1
10.1
6.8
6.3
(Million
Dollars)
NA
199.2
193.7
174.3
146.6
148.6
129.2
127.6
125.8
91.7
NA
Source: U.S. Census of Manufacturers, 1972: Annual Survey of Manufactures, 1973, 1974, and 1975.
NA - - Not Available
-------
Table 8.1-2. BASIC INDUSTRY STATISTICS
METAL OFFICE FURNITURE
(SIC 2522)
All Employees
Year
1975
1974
1973
1972
1971
1970
1969
1968
1967
1963
1958
Establish-
ments
(Number)
NA
NA
NA
192
NA
NA
NA
NA
187
170
151
Number
(Thousands)
25.2
31.1
30.1
27.6
25.0
27.6
30.5
27.1
27.0
19.9
17.5
Payroll
(Million
Dollars)
272.0
313.3
286.4
248.2
201.8
205.6
219.4
186.3
178.5
112.1
86.0
Production Workers
Number
(Thousands)
18.5
24.1
22.7
20.6
18.1
20.4
23.1
20.9
21.1
15.8
13.9
Man-Hours
(Millions)
36.5
49.0
46.5
42.6
37.5
42.4
46.5
42.7
42.9
31.5
26.9
Wages
(Million
Dollars)
183.1
221.1
192.4
166.7
134.2
136.3
151.7
128.3
125.3
81.4
62.7
Value
Added by
Manu-
facture
(Million
Dollars)
589.5
645.2
638.9
508.6
415.5
425.2
478.6
398.9
389.3
228.3
173.7
Cost of
Materials,
Fuel
(Million
Dollars)
399.4
436.4
394.8
349.8
263.7
254.2
304.2
262.6
239.5
160.1
109.7
Value of
Industry
Shipments
(Million
Dollars)
981.9
1,069.4
1,023.7
853.7
682.5
682.1
764.5
654.2
622.9
390.0
286.0
Gross
Capital Value of
Expendi- Fixed
tures, New Assets
(Million
Dollars)
23.9
25.2
39.6
24.5
14.2
14.2
20.3
32.6
31.5
14.2
5.3
(Million
Dollars)
NA
304.4
302.4
261.5
251.2
248.8
252.9
231.4
207.7
151.5
NA
Source: U.S. Census of Manufacturers, 1972; Annual Survey of Manufactures, 1973, 1974, and 1975
NA - - Not Available
-------
Table 8.1-3. BASIC INDUSTRY STATISTICS
PUBLIC BUILDING AND RELATED FURNITURE
(SIC 2531)
All Employees
Year
1975
1974
1973
1972
1971
1970
1969
1968
1967
1963
1958
Establish-
ments
(Number)
NA
NA
NA
422
NA
NA
NA
NA
438
429
390
Number
(Thousands)
20.0
21.6
22.2
21.4
21.0
23.1
23.4
21.0
22.6
16.9
16.0
Payroll
(Million
Dollars)
173.6
186.1
169.1
157.8
135.5
149.9
154.5
127.7
132.2
83.4
69.3
Production Workers
Number
(Thousands)
15.6
16.9
17.4
16.3
16.3
18.2
18.3
16.4
17.5
13.3
12.6
Man-Hours
(Millions)
28.0
31.7
33.0
31.6
30.9
36.0
37.0
33.1
36.3
26.8
25.8
Wages
(Million
Dollars)
115.8
124.5
112.0
103.8
89.0
101.2
104.6
83.1
89.2
57.4
48.4
Value
Added by
Manu-
facture
(Million
Dollars)
330.3
338.7
299.6
295.9
254.5
255.3
267.4
241.3
233.6
141.8
112.9
Cost of
Materials,
Fuel
(Million
Dollars)
317.1
305.8
265.6
245.9
218.5
214.2
214.2
191.3
194.7
127.9
98.0
Value of
Industry
Shipments
(Million
Dollars)
657.5
643.1
564.9
535.3
471.8
462.6
468.5
432.3
421.2
268.6
208.4
Gross
Capital Value of
Expendi- Fixed
tures, New Assets
(Million
Dollars)
15.8
15.6
13.0
13.0
8.8
18.1
12.1
7.6
10.0
4.4
4.9
(Million
Dollars)
NA
154.8
150.5
143.6
121.3
126.5
109.5
96.4
94.5
66.3
NA
Source: U.S. Census of Manufactures, 1972; Annual Survey of Manufactures, 1973, 1974, and 1975
NA - - Not Available
-------
Table 8.1-4. BASIC INDUSTRY STATISTICS
METAL PARTITIONS AND FIXTURES
(SIC 2542)
oo
All Employees
Year
1975
1974
1973
1972
1971
1970
1969
1968
1967
1963
1958
Establish-
ments
(Number)
NA
NA
NA
507
NA
NA
NA
NA
500
513
NA
Number
(Thousands)
21.0
25.6
26.3
26.2
22.2
22.7
25.2
23.4
22.7
20.3
NA
Payroll
(Million
Dollars)
212.3
237.9
231.3
215.7
167.7
166.0
177.4
163.9
152.9
119.3
NA
Production Workers
Number
(Thousands)
14.8
18.4
19.5
19.9
16.7
16.8
18.8
17.6
17.0
14.9
NA
Man-Hours
(Millions)
29.6
37.6
38.7
38.5
30.9
32.7
37.5
35.7
35.1
31.7
NA
Wages
(Million
Dollars)
131.8
150.1
149.1
143.1
107.0
105.8
110.1
102.0
96.0
79.2
NA
Value
Added by
Manu-
facture
(Million
Dollars)
448.2
546.8
444.8
412.4
328.5
324.9
334.6
309.6
302.5
214.3
NA
Cost of
Materials,
Fuel
(Million
Dollars)
406.2
458.3
367.8
326.3
256.8
.257.4
251.0
220.2
213.0
165.7
NA
Value of
Industry
Shipments
(Million
Dollars)
868.3
987.6
805.6
734.5
580.1
579.0
583.8
524.1
512.0
377.8
NA
Gross
Capital Value of
Expendi- Fixed
tures, New Assets
(Million
Dollars)
21.6
22.2
22.7
19.4
13.3
14.9
12.5
13.4
19.9
8.5
NA
(Million
Dollars)
NA
239.3
242.7
237.5
NA
NA
172.5
156.6
150.6
117.8
NA
Source: U.S. Census of Manufactures, 1972; Annual Survey of Manufactures, 1973, 1974, and 1975
NA - - Not Available
-------
Table 8.1-5. BASIC INDUSTRY STATISTICS
METAL FURNITURE INDUSTRY
(TOTAL FIGURES FOR SIC 2514, 2522, 2531, 2542)
All Employees
Year
1975
1974
1973
1972
1971
1970
1969
1968
1967
1963
1958
Establish-
ments
(Number)
NA
NA
NA
1,588
NA
NA
NA
NA
1,611
1,629
NA
Number
(Thousands)
94.3
113.7
115.5
109.6
99.7
105.8
111.9
103.6
103.3
86.4
NA
Payroll
(Million
Dollars)
891.4
994.8
940.4
844.2
699.2
709.6
732.7
647.3
619.1
443.6
NA
Production Workers
Number
(Thousands)
71.4
88.2
90.2
85.4
76.9
82.1
87.8
81.4
81.4
68.3
NA
Man-Hours
(Millions)
135.6
172.1
177.1
166.4
149.0
161.5
173.4
162.7
164.6
137.9
NA
Wages
(Million
Dollars)
586.1
672.6
631.4
571.2
463.9
474.6
499.0
433.9
420.1
310.0
NA
Value
Added by
Manu-
facture
(Million
Dollars)
1,804.6
2,014.3
1,892,1
1,664.1
1,384.8
1,371.2
1,426.8
1,283.7
1,216.7
831.4
NA
Cost of
Materials,
Fuel
(Million
Dollars)
1,600.9
1,729.9
1,534.8
1,374.4
1,119.4
1,086.5
1,122.2
1,007.3
959.2
734.4
NA
Value of
Industry
Shipments
(Million
Dollars)
3,438.3
3,703.1
3,394.0
3,013.9
2,498.3
2,448.6
2,513.9
2,274.9
2,161.4
1,560.7
NA
Gross
Capital Value of
Expendi- Fixed
tures, New Assets
(Million
Dollars)
76.0
81.2
100.8
73.8
47.1
61.0
57.8
63.7
71.5
33.9
NA
(Million
Dollars)
NA
897.7
889.3
816.9
NA
NA
664.1
612.0
578.6
427.3
NA
Source: Derived From Data in U.S. Census of Manufactures, 1972, and in Annual Survey of Manufactures,
1973, 1974, and 1975.
NA - - Not Available
-------
In 1972, the last year for which data is available, 1,588 establishments were
listed by the U.S. .Census of Manufacturers as engaged in metal furniture
manufacturing. The number of establishments devoted to metal furniture manufactu-
ring has declined, but only slightly, from the 1967 level of 1,611 establishments for
the industry as a whole. The number of establishments involved in metal household
and public building and related furniture manufacturing decreased slightly from 1967
to 1972, and increased slightly for metal office furniture and metal partitions and
fixtures. Generally, the number of establishments in the metal furniture industry has
been relatively stable with only moderate rates of exit and new entry.
8.1.3. Industry Growth: Past and Projected
The metal furniture industry, as a manufacturer of capital goods and consumer
durable goods, is quite volatile relative to changes in the United States economy as a
whole. Table 8.1-6 presents the value of metal furniture industry shipments in
current and constant 1972 dollars, as well as real gross national product, also
expressed in 1972 dollars. Figure 8.1-1 presents the industry's shipments in constant
dollars and real GNP graphically. As is readily evident, activity in the metal
furniture industry expands more rapidly than GNP during the growth phase of the
business cycle, and contracts more quickly during a period of decline (or even slow
growth). Figure 8.1-2 presents a graph of a more direct measure of this phenomenon:
annual percentage changes in real GNP and real shipment of metal furniture.
In addition to the volatility of the metal furniture industry, Figure 8.1-2 also
illustrates a lag in the industry's reaction to shifts in the economy. In 1971, GNP
grew at a real rate of increase of 3.0 percent, but metal furniture shipments
continued the decline of the economic downturn in 1970; in 1972, however, the
industry made up for lost time by growing by almost 19 percent over 1971. The
industry did not lag the arrival of the recession of 1974 to 1975, however, as
shipments dropped by more than 7 percent in 1974.
8-7
-------
Table 8.1-6. VALUE OF METAL FURNITURE INDUSTRY
SHIPMENTS IN CURRENT AND CONSTANT DOLLARS,
1967 - 1975
Value of Industry Wholesale Price Value of Industry Gross National
Shipments Index for Com- Shipments Product
(Millions of Cur- mercial Furniture (Millions of 1972 (Billions of 1372
Year rent Dollarsa (1972=100)° Dollars)6 Dollarsr
1975
1974
1973
1972
1971
1970
1969
1968
1967
3,438.3
3,703.1
3,394.0
3,013.9
2,498.3
2,448.3
2,513.9
2,274.9
2,161.4
138.7
126.8
107.7
100.0
98.3
95.3
89.9
86.4
83.2
2,478.9
2,920.4
3,151.3
3,013.9
2,541.5
2,569.4
2,796.3
2,633.0
2,597.8
1,191.7
1,210.7
1,233.4
1,171.1
1,107.5
1,075.3
1,078.8
1,051.8
1,007.7
a
b
c
d
Source: Table 8.1-5.
Source: U.S. Bureau of Labor Statistics, Wholesale Prices and Price Indexes.
Note: This index is published with 1967=100. It has been converted
to 1972=100 to facilitate comparison with constant dollar GNP.
Equals value in current dollars divided by (Index '- 100).
Source: Statistical Abstracts of the United States, 1976.
8-8
-------
Figure 8.1-1. REAL GROSS NATIONAL PRODUCT AND METAL
FURNITURE INDUSTRY SHIPMENTS IN CONSTANT DOLLARS,
1967 - 1975
1500 -
Gross National
Product (Billions
of 1972'Dollars)
1000 -
I I I I I I I I I
1967 1968 1969 1970 1971 1972 1973 1974 1975
3000 H
Value of Metal
Furniture Industry
Shipments (Millions
of 1972 Dollars)
2500 -
2000 -
I 1 I I I I I I I
1967 1968 1969 1970 1971 1972 1973 1974 1975
Source: Table 8.1-6.
8-9
-------
Figure 8.1-2. PERCENT CHANGE FROM PREVIOUS YEAR
IN REAL GROSS NATIONAL PRODUCT AND CONSTANT
DOLLAR METAL FURNITURE INDUSTRY SHIPMENTS
20 -
10 -
Percent 0 -
GNP
Metal Furniture
Shipments
-10 -
\
\
I I I i i > i i
1968 1969 1970 1971 1972 1973 1974 1975
8-10
-------
In an industry which exhibits such volatility, calculating historic growth rates
can yield vastly different results depending on the span of years chosen for analysis.
Specifically, growth correlations for the most recent available data for 1974 and 1975
probably understates the secular growth trend.a To avoid this difficulty, the annual
compound growth rate may be calculated between the two most recent shipment
peaks, 1969 and 1973. During those four years, real shipments growth averaged 3.0
percent per year.
We estimate long-term growth of real industry shipments will average 2 to 3
percent per year. While data for the entire industry is not yet available for 1976,
statistics for one segment of the industry indicate the industry is repeating its
traditional pattern of recovering from a dip in the economy with growth faster than
the economy as a whole, and in line with historic growth rates.
According to the Business and Institutional Furniture Manufacturer's Associa-
tion, office furniture shipments increased at a real rate of 12 percent in 1976 over
the 1975 level. And during the first eight months of 1977, shipments in real terms
were 24 percent above 1976 levels. Applying those growth rates to the industry as a
whole for 1976 and 1977 implies shipments for 1977 (in 1972 dollars) of $3,443
million. Growth of shipments from the 1973 peak to 1977, using that assumption,
averaged 2.2 percent per year. Thus the recovery of the metal furniture industry
sales from the most recent recession tends to support a secular growth trend of 2 to 3
percent, following the trends of the last decade.
For example, a least squares fit of real industry shipments versus time, using a
constant growth rate model, results in a 1.4 percent annual real growth rate from
1967 to 1975. The latest years are heavily weighted in this model.
From 1969 to 1973, metal office furniture shipments grew at almost exactly the
same rate as the metal furniture industry as a whole.
8-11
-------
8.1.4. Industry Structure
The metal furniture industry is quite fragmented. Table 8.1-7 presents
concentration ratios for the four appropriate SIC classifications and none of the four
shows enough concentration in the top four firms to indicate market dominance by
one or even a few firms.
Metal office furniture (SIC 2522) is the most concentrated of the four
classifications, with the top four firms having accounted for 37 percent of the value
of shipments in 1972. Concentration increased slightly from 1967 to 1972, but not
enough to imply a trend.
Some increase in concentration has also occurred in metal household furniture,
but the increase is very small. In public building and related furniture and in metal
partitions and fixtures, concentration has actually decreased.
Table 8.1-8 offers a look at the role of small firms in the metal furniture
industry. In the economy as a whole, single-unit firmsa accounted for only 19 percent
of the value of shipments by all manufacturing establishments. But in metal
household furniture, public building and related furniture, and metal partitions and
fixtures, single-unit firms accounted for at least double that proportion of the value
of shipments, 38, 44 and 42 percent respectively. Only in metal office furniture did
the 17 percent of single-unit firms fall near the level of single-unit firms in the
economy as a whole. Small manufacturers play a more important role in the metal
furniture industry than in the economy as a whole.
A view of the economics of plant size in the metal furniture industry can be
obtained from Table 8.1-9, which lists the percent of number of establishments,
production worker man-hours, and value added by manufacture for establishments of
various sizes, classified by the number of employees per establishment. Establish-
ments with less than 20 employees account for more than 50 percent of the number of
establishments in metal household furniture, public building and related furniture, and
metal partitions and fixtures. The smaller establishments, of course, account for a
much lower percentage of the value added by manufacture by the industry than for
the number of establishments.
The U.S. Bureau of the Census defines single-unit firms as one with a single
establishment for both manufacturing and administration.
8-12
-------
Table 8.1-7. CONCENTRATION RATIOS IN
METAL FURNITURE MANUFACTURING
Percent of Value of Shipments
Accounted for by;
4 Largest 8 Largest 20 Largest 50 Largest
Companies Companies Companies Companies
Metal Household Furniture
(SIC 2514)
1972 14
1967 12
1963 12
1958 12
Metal Office Furniture
(SIC 2522)
1972 37
1967 32
1963 29
1958 33
Public Building and Re-
lated Furniture
(SIC 2531)
1972 18
1967 18
1963 21
1958 24
Metal Partitions and Fixtures
(SIC 2542)
1972 13
1967 19
1963 19
1958 (NA)
23
21
18
19
49
45
45
49
26
30
32
34
22
27
26
(NA)
41
35
31
33
70
69
69
73
40
46
45
47
39
43
41
(NA)
65
56
53
52
88
88
88
89
59
64
62
65
59
64
61
(NA)
Source: U.S. Census of Manufactures, 1972, Concentration Ratios in Manufacturing.
NA — Not Available
8-13
-------
Table 8.1-8. PERCENT OF VALUE ADDED IN METAL
FURNITURE MANUFACTURING BY MULTI-UNIT AND
SINGLE-UNIT COMPANIES, 1972
Multi-Unit
Companies
Single-Unit
Companies
Percent
All Manufacturing Establishments
Metal Household Furniture
(SIC 2514)
Metal Office Furniture
(SIC 2522)
Public Building and Related
Furniture (SIC 2531)
Metal Partitions and Fixtures
(SIC 2542)
81
62
83
56
58
19
38
17
44
42
Source: U.S. Census of Manufactures, 1972, Type of Organization.
8-14
-------
Table 8.1-9. DISTRIBUTION BY FIRM SIZE IN THE METAL FURNITURE INDUSTRY
OF ESTABLISHMENTS, PRODUCTION WORKERS AND VALUE ADDED
BY MANUFACTURE, 1972
(Share of Total, Percent)
Metal Household Furniture
(SIC 2514)
Metal Office Furniture
(SIC 2522)
oo
I
Firm Size
(Number of
Employees per
Establishment)
1 to 19
20 to 49
50 to 99
100 to 249
250 to 499
500 to 999
1,000 to 2,499
2,500 or More
1 to 19
20 to 49
50 to 99
100 to 249
250 to 499
500 to 999
1,000 to 2,499
2,500 or More
Number of
Establishments
(Percent)
50.7
18.0
10.3
13.1
6.2
1.3
0.4
53.8
20.9
11.4
10.2
2.8
0.7
0.2
Production Value Added
Worker by
Man-hours Manufacture
(Percent) (Percent)
4.9 5.0
8.2 7.3
10.3 10.6
29.7 30.5
31.3 29.2
15.7 17.5
(NA) (NA)
Public Building and Related
Furniture
(SIC 2531)
6.6 6.8
13.6 11.1
18.0 16.2
30.9 31.1
18.3 19.0
12.6 15.7
(NA) (NA)
Production
Number of
Establishments
(Percent)
39.1
14.1
15.6
18.2
6.3
4.2
2.1
0.5
Metal
52.3
22.5
12.0
8.9
2.4
1.4
Worker
Man-hours
(Percent)
1.3
3.5
7.7
19.7
16.9
21.5
29.3
(NA)
Partitions
Fixtures
(SIC 2542)
7.3
14.0
17.7
31.2
13.8
16.1
Value Added
by
Manufacture
(Percent)
1.3
2.7
7.4
16.2
17.7
20.6
34.1
(NA)
and
7.1
13.3
14.6
29.4
16.5
19.2
Source: U.S. Census of Manufactures, 1972
NA = Not Available
-------
In the case of all four industry segments, the very largest plants in the industry
have the greatest labor productivity. For instance, in metal office furniture, in the
largest plants, 29.5 percent of production workers man-hours are able to produce 34.1
percent of the value added by manufacture. (See Table 8.1-9.) However, just because
one plant is larger than another does not necessarily mean that the larger plant is
more efficient; a threshold effect is evident. Some intermediate sizes of
establishments, for example, those with 100 to 249 or 500 to 999 employees in metal
office furniture, account for a lower percentage of value added by manufacture than
of production worker man-hours. At present, no economies of scale are evident in the
metal furniture industry which prohibit a small manufacturer from competing,
especially in regional markets where lower labor productivity may be overcome by
lower distribution costs.
8.1.5. Channels of Distribution
The four segments of the industry market through different outlets; the one
common denominator is that a large number of outlets sell to end-users. The 1972
Census of Retail Trade reported that 32,987 establishments marketed furniture and
sleep equipment. One manufacturer estimated that 25,000 outlets handle metal office
furniture; another manufacturer of outdoor furniture estimated that 30,000 to 60,000
retail outlets offer outdoor furniture. No single manufacturer is represented in the
majority of end-user outlets.
Furniture marts play a major role in the marketing of metal household, metal
office and public building and related furniture. At these martsa buyers gather to
examine the products of a large number of manufacturers. Such marts are extremely
competitive. The furniture mart provides a mechanism for smaller manufacturers to
compete without maintaining regional showrooms which are characteristic of some
larger manufacturers.
Metal partitions and fixtures are marketed primarily through locally owned
distributors who usually carry or offer the products of a large number of
manufacturers. Price competition in this market is therefore particularly keen, as
end-users can compare prices of various manufacturers in one location. The number
of such distributors is quite large; in addition to shelves, lockers, storage bins and
other fixtures, such outlets often carry related products such as material handling
equipment.
a Two key marts are in Chicago and High Point, North Carolina.
8-16
-------
8.1.6. Industry Markets
Table 8.1-10 presents the product mix of the metal furniture industry as a
percent of the value of total industry shipments. No major changes in product mix
have occurred since 1967.
The most important development in metal furniture marketing of the last
decade has occurred in the office furniture market, which includes not only metal
office furniture (SIC 2522) but also metal partitions and fixtures (SIC 2542). With the
growing importance of white collar and service workers in the American economy,
managers have turned their attention more and more to white collar productivity. A
major issue has been, of course, the office environment. Metal furniture
manufacturers have responded to this change in the marketing environment with
increased attention to the need for systems — not just desks and chairs and room
dividers, but modular units that can be fitted together in a number of ways. As
Hauserman Inc., stated in its 1977 annual report, "Our strategy has been to broaden
our opportunities in the office furniture market by improving user productivity. We
accomplish this through easy movability, our ability to reorganize the wiring, lighting,
communications, and other services of the building, and our accommodating individual
furniture needs of office people." Herman Miller Inc., in its 1977 10-K report to the
Securities and Exchange Commission, also address the issue of systems marketing:
"The principal business of the company is the research, design, development,
manufacture and sale of modular space division, storage and materials handling
furniture systems and other furniture products such as chairs, tables, desks and
general purpose seating. Most of these products and systems are coordinated in
design so that they may be used together and interchangeably."
8.1.7. Labor and Materials Costs
Labor and materials and fuel costs have represented roughly constant share of
the value of industry shipments during the past decade.a No major changes in the
industry's cost structure are apparent. Table 8.1-12 offers a detailed view of labor
productivity in the industry. With one exception - - the most recent period in the
metal household furniture industry - - labor productivity has grown more rapidly than
the average hourly earnings of production workers during the periods analyzed. The
productivity gains in metal office furniture and metal partitions and fixtures in the
1972 to 1975 period are particularly noticeable.
p
Table 8.1-11 reveals a decline in labor costs to 1975, but this is difficult to
interpret correctly due to the recession of that year.
8-17
-------
Table 8.1-10. METAL FURNITURE PRODUCT MIX, 1963 - 1975
(As Percent of Value of Total Industry Shipments)
Metal Household Furniture
(SIC 2514)
Dining, breakfast
Kitchen
Porch, lawn, outdoor
Other
Metal Office Furniture
(SIC 2522)
Office seating
Desks
Cabinets, cases
Other
Public Building and Related
Furniture (SIC 2531)
School furniture
Non-school furniture
Other
Metal Partitions and Fixtures
(SIC 2542)
Partitions
Shelving and lockers
Storage racks, accessories
Fixtures
Other
1975 1974 1973 1972 1967 1963
28.1 28.1 29.9 30.1 28.3 33.9
9.2
1.7
6.8
10.5
27.8
7.0
4.5
10.9
5.4
19.5
7.2
11.8
0.5
24.7
3.4
8.0
4.7
6.6
1.9
8.9
1.7
6.8
10.7
29.5
7.7
5.5
11.2
5.1
17.4
6.7
10.1
0.6
25.0
3.1
7.8
5.5
6.6
2.1
8.5
2.7
6.1
12.5
28.9
7.5
5.5
11.4
4.5
17.3
6.3
9.7
1.3
24.0
2.5
8.2
3.4
8.3
1.5
8.6
2.5
6.2
12.8
27.4
6.8
5.4
10.5
4.8
17.4
6.4
9.8
1.2
25.0
2.8
8.3
3.3
7.6
3.0
7.9
2.7
5.3
12.4
28.2
6.4
7.3
9.6
4.9
18.8
7.6
10.1
1.0
24.7
(NA)
(NA)
(NA)
(NA)
(NA)
9.4
4.2
6.8
13.5
23.9
4.9
5.9
9.6
3.6
17.6
7.9
9.0
0.7
24.6
(NA)
(NA)
(NA)
(NA)
(NA)
Source: Annual Survey of Manufactures, U.S. Census of Manufactures.
NA — Not Available
8-18
-------
Table 8.1-11. LABOR AND MATERIALS COSTS IN METAL
FURNITURE MANUFACTURING RELATIVE TO VALUE OF
INDUSTRY SHIPMENTS
As % of Value of Shipments
Year
1975
1974
1973
1972
1971
1970
1969
1968
1967
1963
1958
Production
Workers'
Wages
17.0
18.2
18.6
19.0
18.6
19.4
19.8
19.1
19.4
19.9
20.2
Cost of
Materials,
Fuel
46.6
46.7
45.2
45.6
44.8
44.4
44.6
44.3
44.4
47.1
48.7
Source: Derived from Table 8.1-5.
8-19
-------
Table 8.1-12. TRENDS IN WAGES AND PRODUCTIVITY
IN THE METAL FURNITURE INDUSTRY,
1958 - 1975
oo
Metal Household Furniture
(SIC 2514)
Metal Office Furniture
(SIC 2522)
Public Building and
Related Furniture
(SIC 2531)
Metal Partitions and Fixtures
(SIC 2542)
Average
Hourly
Earnings of
Production
Year
1975
1974
1973
1972
1967
1963
1958
Average
Annual
Compound
Growth
Rates from:
Percent
1958-1975
1967-1975
1972-1975
Workers
3.74
3.29
3.02
2.93
2.18
1.92
1.85
4.20
7.00
8.50
Value Added
per Man-hour
of Production
Workers
10.52
8.99
8.64
8.32
5.79
5.16
4.54
5.10
7.70
8.10
Average
Hourly
Earnings of
Production
Workers
5.02
4.51
4.14
3.91
2.92
2.58
2.33
4.60
7.00
8.70
Value Added
per Man-hour
of Production
Workers
(Dollars)
16.15
13.17
13.74
11.94
9.08
7.24
6.45
5.50
7.50
10.60
Average
Hourly
Earnings of
Production
Workers
4.14
3.93
3.39
3.28
2.46
2.14
1.88
4.80
6.70
8.10
Value Added
per Man-hour
of Production
Workers
11.80
10.68
9.08
9.36
6.44
5.29
4.38
6.00
7.90
8.00
Average
Hourly
Earnings of
Production
Workers
4.45
3.99
3.85
3.72
2.73
2.50
(NA)
(NA)
6.30
6.20
Value Added
per Man-hour
of Production
Workers
15.14
14.54
11.49
10.71
8.61
6.77
(NA)
(NA)
7.30
12.20
NA -
of Manufactures, Annual Survey of
Available
-------
Coating materials cost varies in importance among the four segments analyzed
here, as shown in Table 8.1-13. Cost is relatively higher for metal office furniture
and metal partitions and fixtures, as it to be expected, for in major, high-volume
products in these segments, e.g., file and storage cabinets and industrial shelving,
coating is more important in the manufacturing process, and metal processing is less
important than in the production of, for example, wrought iron lawn chairs.
The relative importance of coating material costs detailed in Table 8.1-13 is
borne out by direct industry estimates of total coating costs as a percentage of total
manufacturing costs. A manufacturer of hospital beds (public building and related
furniture) reports that coating costs, including both materials and the cost of their
application, run about 4 percent of total manufacturing costs; a company specializing
in industrial shelving, office desks and file cabinets reports that total coating costs
average 10 to 12 percent of total manufacturing costs.
8.1.8. Financial Performance
A wide range of financial performance is to be expected in an industry as
fragmented as metal furniture. Table 8.1-14 bears out this expectation for some of
the largest manufacturers' of metal furniture. There is a wide range of profitability
even among these firms.
8.1.9. Imports and Exports
Imports and exports are extremely small in the metal furniture industry, and
do not play a significant role in industry conduct in the United States.
8-21
-------
Table 8.1-13. METAL FURNITURE COATING MATERIALS COST
VS. TOTAL MATERIALS COST AND VALUE OF SHIPMENTS,
1972 AND 1967
Coating Materials Costs
1972
Percent of
Cost of
Materials
Percent of
Value of
Industry
Shipments
1967
Percent of
Cost of
Materials
Percent of
Value of
Industry
Shipments
Metal Household Furniture
(SIC 2514)
Metal Office Furniture
(SIC 2522)
1.7
3.2
0.8
1.0
2.1
4.1
1.0
1.3
Public Building and
Related Furniture
(SIC 2531)
1.9
0.8
1.9
0.8
Metal Partitions and Fixtures
(SIC 2542)
3.6
1.4
4.7
1.8
Source: Census of Manufactures
8-22
-------
to
GO
Table 8.1-14. FINANCIAL RATIOS FOR SELECTED METAL FURNITURE MANUFACTURERS
(Date Indicates End of Fiscal Year)
G. F. Business Lyon Metal Virco
Equipment Inc. Hauserman Inc. Herman Miller Inc. Hon Industries Inc. Products Inc. Manufacturing Corp.
12/76 12/75 6/77 6/76 5/77 5/76 12/76 12/75 12/76 12/75 1/77 1/76
Cost of Sales
as Percent of
Net Sales 83.4 80.1 77.3 77.9 59.2 56.5 65.0 66.2 68.5 69.5 71.1 69.2
Net Income
as Percent of
Net Sales 0.0 0.8 1.7 4.1 5.1 5.3 7.2 6.6 5.0 4.2 2.4 2.7
Return on
Equity
Percent 0.0 1.8 5.9 14.3 19.6 15.5 23.3 20.6 7.5 6.0 14.9 15.9
Source: Annual reports, 10-K filings with the Securities and Exchange Commission.
-------
8.1.10. Geographic Distribution
The metal furniture industry is not concentrated in any single area of the
country, as Table 8.1-15 indicates. It should be noted that for metal office furniture,
public building and related furniture, and metal partitions and fixtures, a preponder-
ance of larger establishments are located in the North Central states. These states
account for a much larger share of the value added by manufacture than for number
of establishments. These states contain the largest manufacturing plants. Table 8.1-
16 presents a more detailed breakdown on the location of establishments throughout
the United States.a
a Data in Table 8.1-16 on the geographical distribution of the establishments must
be used with care; as data in Table 8.1-15 on the North Central states indicates,
percent of establishments do not necessarily coincide with percent of value
added by manufacture (and thus with percent of employment). Due to the need
to maintain confidentiality from census surveys, data on value added by
manufacture and percentage of production workers is often not available for the
finer geographic breakdowns in Table 8.1-16.
8-24
-------
Table 8.1-15. GEOGRAPHICAL DISTRIBUTION OF
ESTABLISHMENTS AND VALUE ADDED BY MANUFACTURE,
METAL FURNITURE INDUSTRY, 1972
Share of
Establishments
(Percent)
Share of
Value Added
by Manufacture
(Percent)
Metal Household Furniture
(SIC 2514)
North East
North Central
South
West
Metal Office Furniture
(SIC 2522)
North East
North Central
South
West
Public Building and Related Furniture
(SIC 2531)
North East
North Central
South
West
Metal Partitions and Fixtures
(SIC 2542)
North East
North Central
South
West
33.8
19.1
28.5
18.6
33.2
32.6
15.8
18.4
19.0
32.5
30.6
18.0
39.3
30.0
16.6
14.2
(NA)
(NA)
35.2
17.2
27.7
51.8
12.6
7.9
14.7
43.5
28.7
13.0
27.5
49.5
15.3
7.7
Source: Derived from U.S. Census of Manufactures, 1972.
Note: North East includes New England and Middle Atlantic states; North Central
states in East North Central and West North Central; South states in the
South Atlantic, East South Central, and West South Central; and West states
in the Mountain and Pacific regions. Individual states within the divisions are
listed in Table 8.1-16.
NA - - Not Available
8-25
-------
Table 8.1-16. GEOGRAPHICAL DISTRIBUTION OF METAL
FURNITURE INDUSTRY ESTABLISHMENTS, 1972
(In Percent of Number of Establishments)
New England
Middle Atlantic
East North Central
West North Central
South Atlantic
East South Central
West South Central
Mountain
Pacific
Metal
Household
Furniture
SIC 2514
(Percent)
Metal
Office
Furniture
SIC 2522
(Percent)
Public Building
and Related
Furniture
SIC 2531
(Percent)
5.1
28.7
16.3
2.8
16.1
7.1
5.4
1.5
17.1
3.1
28.6
25.0
8.9
7.3
4.7
4.2
0.5
17.7
4.5
14.5
24.9
7.6
11.4
8.5
10.7
4.0
14.0
Metal
Partitions
and Fixtures
SIC 2542
(Percent)
Total
Industry
SIC 2514,
2522,
2531,
2442
(Percent)
4.3
34.9
23.3
6.7
6.9
4.1
5.5
1.0
13.2
4.5
26.9
21.9
6.0
10.8
6.2
6.7
1.9
15.1
Total Establishments
(Number)
467
192
422
507
1,588
Source: 1972 Census of Manufactures.
Note: The above classifications contain the states indicated below:
New England: Main, New Hampshire, Vermont, Massachusetts, Rhode Island,
Connecticut; Middle Atlantic: New York, New Jersey, Pennsylvania; East North
Central: Ohio, Indiana, Illinois, Michigan, Wisconsin; West North Central:
Minnesota, Iowa, Missouri, North Dakota, South Dakota, Nebraska, Kansas; South
Atlantic: Delaware, Maryland, District of Columbia, Virginia, West Virginia, North
Carolina, South Carolina, Georgia, Florida; East South Central: Kentucky,
Tennessee, Alabama, Mississippi; West South Central: Arkansas, Louisiana,
Oklahoma, Texas; Mountain: Montana, Idaho, Wyoming, Colorado, New Mexico,
Arizona, Utah, Nevada; Pacific: Washington, Oregon, California, Alaska, Hawaii.
8-26
-------
8.2. COST ANALYSIS OF ALTERNATIVE EMISSION CONTROL SYSTEMS
Cost models were prepared as guides to show average costs for coating lines
subject to new source performance regulations. A wide variety of coating line sizes
and outputs are used in the metal furniture industry. To adequately cover this
industry it was decided to construct two basic and distinct cost models. A relatively
small line coating 3000,000 square feet per year (278,707 square meters), was chosen
to compare solvent-borne, water-borne, high solids and powder coating all by
electrostatic spray, and add-on controls. A larger output line capable of coating
approximately 23,000,000 square feet per year (2,086,957 square meters) was selected
to compare solvent-borne and water-borne dip coatings, electrodeposition and
appropriate add-on controls. Such lines are used for high volume coating where high
quality is not a prerequisite and where few colors are involved or for long runs of a
single color . It is not the intent to show any cross comparisons between these two
line sizes but to compare each on its own merits on a separate basis. The choice of
lines should not be construed as limiting spray coating only to small lines or dip
coating to very large lines. It is merely an attempt to show actual production
situations.
Metal furniture manufacturers normally apply only one coat varying in
thickness from .005" to .0015" depending on the product and the color -lighter colors
tend to be applied thicker because of less hiding power. It is difficult to apply powder
coatings much less than .002" in commercial production and get an acceptable finish.
(See Table 4-1, Chapter 4 for typical thicknesses.) High solids coatings, because of
their higher viscosities, also tend toward thicker coatings and are normally applied in
o
the .001" to .0015" range . For the smaller electrostatic spray lines, a dry coating
thickness of .001" was assumed for the conventional solvent-borne and water-borne
coating models. For high solids coating, a thickness of .00125" was assumed and for
powder coating, a thickness of .002" was assumed. For the dip coat and EDP lines, a
coating thickness of .001" was assumed for the costing models. The majority of firms
visited worked only one shift. The costing models, therefore, were based on one 8
hour shift, 240 days per year or 1920 hours per year. Capital costs include all
equipment used in the coating operations except washing or other metal pretreatment
equipment. Building space is included at 30
-------
Capital costs used in the models reflect a typical installation where normal
color changes are programed within the production cycle for efficient operation.
Facilities requiring rapid color changes would have to be treated on an individual
basis.
With the add-on controls it was assumed that all the solvents emitted from
application areas and ovens went through the control unit. Most water wash spray
booths have recirculating water systems. Any solvent from overspray that is
3
captured by the water curtain is eventually evaporated into the air exhaust system .
Both incinerators and carbon adsorbers were figured as operating at an average
efficiency of 90 percent.
For the smaller line, two add-on controls and three alternative painting
methods were considered. Cost models are as follows:
Table 8.2-1. CASE CODES A-l - A-7
Code
A-l Base Case - Solvent-borne coating
electrostatic spray - no controls
A-2 Base Case - thermal incinerator on oven only
A-3 Base Case - carbon adsorber on spray booth
and flash-off area
A-4 High solids coating - electrostatic spray
A-5 Powder coating - electrostatic spray
A-6 Water-borne coating - electrostatic spray
A-7 Base Case - carbon adsorber on spray booth
and flash-off area and incinerator on oven
For the larger line, two add-on controls and two alternative coating methods
were selected as follows:
8-28
-------
Table 8.2-2. CASE CODES B-l - B-6
Code
B-l Base Case - solvent-borne coating - dip coat
B-2 Water-borne coating - electrodeposition (EDP)
B-3 Solvent-borne dip coat - carbon adsorber on dip
tank exhaust and flash-off area
B-4 Solvent-borne dip coat - thermal incinerator on
oven exhaust. Primary heat recovery.
B-5 Solvent-borne dip coat - carbon adsorber on dip
tank and flash-off area and incinerator on oven.
B-6 Water-borne coating - dip coat
Pertinent cost and emission data as developed from the cost models are shown
in Table 8.2-3, Part I and Table 8.2-4, Part II, in order of increasing emission.
8.2.1. Cost Effectiveness Summarized -New Facilities
For new facilities the two most cost effective systems for the lower output
lines are powder coating and high solids coating. The latter system achieves high
emission reduction with no annual cost penalties in the model costed. The powder
coating showed only a modest increase in annual costs (about 2 percent) over the
conventional solvent-borne base case.
Powder coating of metal furniture is already an accepted practice, being used
by many manufacturers for applying coating thicknesses of .0015" and above. Six of
the metal furniture companies visited by Springborn Laboratories in the course of this
study used powder coating for at least part of their coating operations. The majority
of applications were by electrostatic spray although fluidized beds were also used for
smaller parts and where heavy coating thicknesses (.006" and over) were desired.
High solids coatings also show potential as a non-polluting, cost saving alternative to
conventional coating methods. Although most work has been done in the medium
solids range of 50 to 60 percent NVV, higher solids coatings are in use. The costing
model was based on 80 percent solids. While considered high by many in the industry,
8-29
-------
a major company visited by Springborn Laboratories is commercially applying an
2 4
alkyd based coating at 80 percent solids after several years of development ' .
Despite considerable interest in high solids coatings, there are very few lines in the
c c
metal furniture industry in commercial operation ' . Materials and application
techniques are still undergoing development.
Water-borne coatings applied by electrostatic spray achieve a high emission
reduction but are potentially more expensive than conventional solvent-borne
coatings. Typical alkyd coatings in a water-borne formulation cost about $1.00 per
7
gallon more than their solvent-borne counterparts . Coating lines are also more
expensive as stainless steel is used in some areas to prevent rusting. There is very
B 8 9
little action in the metal furniture industry with water-borne spray coatings ' ' .
As for control equipment, both carbon adsorption and incineration are
expensive in proportion to amount of emission reduction and are more likely to be
used in retrofit situations than in new facilities.
For the larger output line models, electrodeposition (EDP) is considerably more
cost effective in terms of dollars per ton of reduced emissions than control options
such as incineration or carbon adsorption. It is also more cost effective than water-
borne dip coating primarily because of the cost of coating materials. Capital
investment for EDP is higher than for dip coating, however. It should be noted that
no water-borne dip coating operations were observed by Springborn Laboratories
during industry visits. Water-borne coating materials suitable for dip coating,
however, are available from major suppliers. Costs range 10 to 15 percent higher
than for solvent-borne counterparts.
In the case of both the large and small lines controlling emissions by
incineration on the oven is more expensive than by carbon adsorption on application
and flash-off areas on a cost per ton of solvent removed basis.
Although both spray booth and dip tank emissions are below the 3000 pounds
per day (assuming exempt solvents) allowed by the Los Angeles Rule 66 type
regulations adopted by many states (as long as oven emissions are controlled), cost
models were prepared controlling both application emissions and oven emissions of
the solvent-borne spray line and dip coating line. As can be seen from Table 8.2-3,
Case A-7 and B-5, emissions going into the control device can be reduced by 90
percent by these combinations but costs per ton of emissions reduced is considerably
more than alternative coating methods.
8-30
-------
EraSI
oo
CO
Case
No.
A-5 Powder coating
A-7 Base - adsorber on
spray booth, in-
cinerator on oven
A-4 High solids
A-6 Water-borne
A-3 Adsorber on spray
booth
A-2 Incinerator on oven
A-l Base case - solvent
spray
B-2 EDP dip
B-5 Base - adsorber on
application, incinera-
tor on oven
B-6 Water-born dip
B-3 Adsorber on
application
B-4 Incinerator on oven
B-l
Base case - solvent
dip
Table 8.2-3. ALTERNATIVE C^SES - NEW FACILITIES
METAL FURNITURE - PART I
Model Size - Coating Capacity 3000,000 Square Feet
(278,707 square meters) Per Year
Incremental
KG VOC
Annual Cost Total Coating Increased Cost Emitted Per
Total Annual Over Base Cost Over Base Case Liter Coating
Cost Case $/Sq. Meter $/Sq. Meter (minus water)
2S3.070
288.280
243,810
278.080
276. ISO
260.740
248,610
Model
517.200
572,940
559.590
538,180
548,060
4,460
39,670
(4,800)
29,470
27.540
12,130
—
.910
1.03
.870
.997
.990
.935
.892
.02
.14
(.02)
.11
.10
.04
—
.01*
.0545
.1678
.2272
.1773
.4226
.5457
Cost Per
Metric Ton
of VOC
Percent Controlled
Reduction $/Metric Ton
99* 261
90 2,576
83 0
79 2,195
68 2,347
22 3.110
—
Size - Coating Capacity 22,464,000 Square Feet
(2,086,957 square meters) Per Year
3,900
59,640
46,270
24,880
34,760
.248
.275
.268
.258
.263
.002
.029
.022
.012
.017
.0987
.0348
.2272
.2508
.3490
93 45
90 722
80 630
54 502
36 1,052
513,300
.246
.5457
a
Some volatile organics can be emitted on the order of 0.5 to 3 percent from plasticizers or other
additives. Thermoset resins which comprise the bulk of the market generally emit less than 1 percent.
-------
Table 8.2-4. ALTERNATIVE CASES - NEW FACILITIES
METAL FURNITURE - PART II
Model Size: Coating Capacity 3000,000 Square Feet
(278.707 square meters) Per Year
Case
A-5
A-7
A-4
A-6
A-3
A-2
A-l
Total Capital
Investment
370,000
531,410
350,000
496,000
495,750
439,410
403,750
Increased Capital
Over Base
(33,750)
127,660
(53,750)
92,250
92,000
35,660
—
Solvent
Metric Tons
Per Year
<0.19a
1.7
2.86
3.67
5.5
13.22
17.1
Emitted
Pounds
Per Day
<1.7a
15
26
34
51
121
157
Model Size: Coating Capacity 22,464,000 Square Feet
(2,086,957 square meters) Per Year
B-2
B-5
B-6
B-3
B-4
B-l
629,200
689,420
525,000
570,420
670,420
488,420
140,780
201,000
36,580
82,000
119,000
—
6.2
9.18
18.4
42.23
58.75
91.8
57
84.3
169
388
540
843
Cases correspond to codes on Tables 8.2-1 and 8.2-2
a See footnote on Table 8.2-3
8-32
-------
Only thirteen states currently have statewide regulations controlling organic
solvent emissions from stationary sources, but eight other states with a total of
twelve districts within these states have promulgated individual, non-statewide
regulations. Most of these regulations are based on or are similar to Rule 66 of the
Los Angeles Country Air Pollution Control District.
This regulation limits oven emissions to 15 pounds per day per oven and all
emissions of photoreactive solvents from any machine, equipment, or other
contrivance to 40 pounds per day. The limit on "exempt" solvents is 3000 pounds per
day. The law permits, however, these limits to be exceeded if the total emissions
have been reduced by 85 percent or more. Most of the state and local regulations
follow these limits closely.
The affected facilities in the coating line are assumed to be the application
and flash-off area and the oven. As can be seen from Table 8.2-5 oven emissions
from the smaller line are controlled to below the 15 pounds per day limit by
incineration, high-solids coating and powder coating. Water-borne spray coatings
exceed the 15 pound limit if one assumes that 50 percent of the solvents are emitted
from the oven. This has found to be so in other industries (automotive) because
higher boiling solvents are generally used in water-borne coatings than in convention-
al solvent-borne coatings where 10 to 30 percent of emissions are from the oven .
The use of water-borne coatings with a solvent content of not over 20 percent of the
liquid contents, however, provides exemption from most state and local emission
control laws.
For the large dip coat line only EDP coatings fall below the 15 pound level. As
stated above, however, the Rule 66 type laws allow this limit to be exceeded provided
emissions are reduced by at least 85 percent which is the case with incineration.
Four states and four districts have upper limits on the amounts of exempt
(non-photoreactive) solvents emitted from sources other than ovens. These generally
follow Rule 66, which places a limit of 3000 pounds per day - except for Connecticut,
which has a limit of 800 pounds per day. In all of the model cases shown, these limits
were not exceeded even with no controls, assuming of course, that exempt solvents
are being used. It is the latest EPA purpose, however, to place limits on all solvent
11 12
emissions not just those that are avtively photoreactive ' .
8-33
-------
Table 8.2-5. METAL FURNITURE COATING
SOLVENT EMISSIONS FROM AFFECTED FACILITIES
Model Size: Capacity 3,000 Square Feet
278,707 square meters) Per Year
Model Case No.
A-l
A-2
A-3
A-4
A-5
A-6
A-7
Application Area
Metric Tons
Per Year
12.83
12.83
1.28
2.15
0
1.84
1.28
Pounds
Per Day
118
118
11.8
19.7
0
16.87
11.8
Oven
Metric Tons
Per Year
4.27
.43
4.27
0.72
<0.19a
1.84
.43
Pounds
Per Day
39
3.9
39
6.6
<1.7f
16.9
4
a
Model Size: Coating Capacity 22,464,000 Square Feet
(2,086,957 square meters) Per Year
B-l
B-2
B-3
B-4
B-5
B-6
55.08
5.62
5.51
55.08
5.51
11.04
506
52
51
506
51
101
36.72
0.62
36.72
3.67
3.67
7.36
337
6
337
34
34
68
Cases correspond to codes on Tables 8.2-1. and 8.2-2.
a
See footnote on Table 8.2-3.
8-34
-------
8.2.2. Reconstructed Facilities
Add-on controls for all intents and purposes will cost about the same as on new
facilities providing space is available especially for large carbon adsorbers on spray
booths and providing emissions are similar to a new facility using solvent-borne spray
or dip coating. Since the latter could vary depending on the coating system chosen, it
was assumed for costing purposes that the reconstructed lines had the same outputs
and solvent emissions as the new facilities in Cases A-l and B-l.
Add-on controls used are the same as those used in the new facilities as shown
in Tables 8.2-6 and 8.2-7.
As for alternative coating systems such, as water-borne or high solids, it is
possible that a reconstructed facility could be altered to accomodate these. Each
case will be different, however, depending on the degree of reconstruction. For
example, it might be possible to switch to a high solids coating just by adding new
guns at a cost of $10,000 to $20,000. A switch to powder coating on the other hand
would require a recovery system as well as a new spray booth at considerable
expense. Since costs to convert to a different coating system will be so variable only
the add-on controls will be considered in this analysis.
Table 8.2-6. CODES A.l-1 - A.l-3
For smaller line:
Code
A.l-1 Thermal incinerator on oven exhaust
A.l-2 Carbon adsorber on spray booth exhaust
A.l-3 Incinerator on oven plus carbon adsorber
on spray booth
For larger line:
Table 8.2-7. CODES B.l-1 - B.l-3
Code
B.l-1 Carbon adsorber on dip tank exhaust
B.l-2 Thermal incinerator on oven exhaust
B.l-3 Carbon adsorber on dip tank plus incin-
erator on oven
Pertinent cost and emission data as developed from cost models are shown in
Tables 8.2-8 and 8.2-9. Costs shown are those for the control option only and are
incremental to the cost of reconstructing the facility.
8-35
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Table 8.2-8. ALTERNATIVE CASES - RECONSTRUCTED FACILITIES
METAL FURNITURE - PART I
Model Size: Coating Capacity 3000,000 Square Feet
(278,707 square meters ) Per Year
Case
A.l-3
A. 1-2
A.l-1
Incremental Incremental Kg VOC Percent
Annual Cost Emitted Per Reduction
Cost $/Sq. Meter Liter Coating Total VOC
39,670 .14
27,542 .10
12,130 .04
.0545 90
.1773 68
.4226 22
Cost Per
Metric Ton
of VOC
Controlled
2,560
2,374
3,110
Model Size: Coating Capacity 22,464,000 Square Feet
(2,086,975 square meters) Per Year
B.l-3
B.l-1
B.l-2
59,640 .03
24,880 .01
34,760 .02
.0348 90
.2508 54
.3490 36
722
502
1,052
Cases correspond to codes on Tables 8.2-6 and 8.2-7
8-36
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Table 8.2-9. ALTERNATIVE CASES - RECONSTRUCTED FACILITIES
METAL FURNITURE - PART II
Model Size: Coating Capacity 3000,000 Square Feet
(278.707 square meters) Per Year
Case
A. 1-3
A. 1-2
A. 1-1
Capital Investment
of Add-on Controls
92,000
56,340
35,660
Solvent
Metric Tons
Per Year
1.7
5.5
13.22
Emited
Pounds Per
15
50
121
Day
Model Size: Coating Capacity 22,864,000 Square Feet
(2,086,957 square meters) Per Year
B.l-3 201,000 9.18 84
B.l-1 82,000 42.23 388
B.l-2 119,000 58.75 540
Cases correspond to codes on Tables 8.2-6 and 8.2-7
8-37
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8.2.3. Water Pollution and Solid Waste Disposal
Control measures such as incineration and carbon adsorption do not contribute
to solid waste disposal problems. Spent carbon is usually returned to the
manufactures and reprocessed. If steam is used to regenerate the carbon bed in the
adsorber unit, any water miscible solvents remaining in the water can be dumped into
the sewer. This can be avoided by incinerating the steam-solvent mixture.
In the electrodeposition process, water pollution and waste disposal of sludge
was initially a problem but in today's modern operation a closed loop recirculating
system is used whereby paint is filtered out using ultrafiltration methods and returned
to the tank. The filtrate is used to rinse off excess paint from the part. A small
amount of filtrate containing excess salts and solubilizers is normally dumped to the
sewer and replaced with deionized water to keep the bath chemistry in balance. In a
13
typical installation, this can amount to around 0.5 gallons per minute
With water-borne spray coatings sludge disposal problems increase compared
to solvent-borne coatings. In the water wash the major portion of the overspray is
thrown out of suspension forming gummy agglomerates requiring more frequent and
more difficult cleaning of settling tanks. Based on information from the automotive
industry, tanks had to be cleaned four times as often compared to solvent-borne
coatings. In the cost model, liquid and sludge disposal costs were increased by 50
percent to reflect this. Disposal costs, however, play a relatively small part in the
overall coating operation costs.
8-38
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8.3. REFERENCES
1. Oge, M.T. Trip Report - Lyon Metal Products, Inc., Aurora, Illinois. Springborn
Laboratories, Inc. (formerly DeBell & Richardson, Inc.). Enfield, Connecticut.
Trip Report 91. March 12, 1976.
2. Oge, M.T. Springborn Laboratories, Inc., Enfield, Connecticut. Telephone
Conversation with Simmons Company, Charlotte, North Carolona. October
1977.
3. Holley, W.H. Springborn Laboratories, Inc. Telephone conversation with Binks
Manufacturing, New Jersey. November 7,1977.
4. Oge, M.T. Trip Report - Guidelines. Springborn Laboratories, Inc. Simmons
Co., Munster, Indiana. Trip Report 41. January 28, 1976.
5. Holley, W.H. Springborn Laboratories, Inc. Telephone conversation with
Ashland Chemical, Columbus, Ohio. August 24,1977.
6. Holley, W.H. Springborn Laboratories, Inc. Telephone conversation with
Hanna Chemical Coatings, Columbus, Ohio. August 25, 1977.
7. Holley, W.H. Springborn Laboratories, Inc. Telephone conversation with Lilly
Industrial Coating, Indianapolis, Indiana. August 20, 1977.
8. Holley, W.H. Springborn Laboratories, Inc. Telephone conversation with
Ransburg Corporation. Indianapolis, Indiana. August 29, 1977.
9. Holley, W.H. Springborn Laboratories, Inc. Telephone conversation with Lilly
Industrial Coatings, Indianapolis, Indiana. August 24, 1977.
10. Air Pollution Engineering Manual, U.S. Department HEW 1967, p 711.
11. EPA declares exempt solvents will not be solution to air pollution. Industrial
Finishing (magazine) April 1976, p 20.
12. EPA Solvent Game Plan, Industrial Finishing. December 1976, p 20.
13. Schrantz, W. UF Benfits Conveyorized Batch-Type EDP Systems, Industrial
Finishing (magazine). November 1972, p 26.
8-39
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9. RATIONALE FOR THE PROPOSED STANDARDS
This chapter presents the rationale for the selection of the emission sources,
pollutants, and emission control systems for use in recommendations for an air quality
standard for stationary sources in the metal furniture industry. Also discussed are
modification and reconstruction considerations. The references for much of the data
contained here are included in Chapters 3 through 8, which chapters develop the data
for these recommendations.
9.1. SELECTION OF SOURCE FOR CONTROL
Section III of the Clean Air Act of 1970 and 1974 extends authority to EPA to
regulate emissions by developing standards of performance for new stationary sources
based on the degree of emission limitations achievable through the application of the
best systems of emission reduction.
Section III (b), which allows EPA to limit emission of pollutants for which air
quality criteria have been prescribed, is appropriate for the metal furniture industry a
major source of hydrocarbon (HC) emissions. Hydrocarbon emissions from metal
furniture finishing lines depend on the ratios of organic solvents to nonvolatile solids
in the coatings used, the transfer efficiency of the method of applying the coatings
and the quantities of coating materials used on the products. For example, lacquers
having 15 to 17 volume percent solids are higher in organic solvents than enamels
consisting of 30 to 35 volume percent solids. Powder coatings have volume percent
volatiles ranging from less than 1 percent to 5 percent and water-borne coatings
contain organic solvents in the range of 12 to 15 percent.
The sources studied are metal furniture and fixture assembly plants where the
products of production are coated in a finishing operation. The coatings are applied
to metal furniture or fixture pieces which will be assembled with other metal, wood,
fabric, plastic or glass parts to form a furniture or fixture assembly. Included in this
category are household furniture, office furniture, institutional furniture and fixtures.
Household and office furniture includes tables, chairs, beds, desks, lockers, benches,
shelving, file cabinets, lamps, room dividers and others. Institutional furniture is
made for hospitals, schools, athletic fields, restaurants, governments offices,
laboratories and other types of institutions.
9-1
-------
Metal furniture assembly plants are generally medium to small in size with
most of the companies employing 100 employees or less. The categories household,
office furniture, institutional and fixtures employ nearly equal numbers of people. In
terms of value of shipments, 50 largest companies had 65 percent of the metal
household furniture market and in the metal office furniture 50 largest companies had
88 percent of the market. The location of about 3000 plants is distributed in the
continental United States in this proportion: 43 percent in the East, 29 percent in the
East Central Region, 12 percent in the West Central Region and 16 percent in the
West and Pacific Coast Regions. Figure 9.1-1 shows this distribution.
The markets of the metal furniture industry are varied. Some companies sell
directly to consumers through retail stores. Other companies do contract jobs for
other manufacturers. Some companies specialize in certain functional furniture and
purchase other pieces from outside sources which they provide to customers as an
integrated suite of furniture.
Typical coating lines operate at speeds of 8 to 24 feet per minute at a
continuous rate or intermittently. A plant may have more than one line. Plants
operate single and multiple shifts depending on work loadings. Applications of
coatings is done by the techniques of spray, dipping and flow coating which are
described in detail in Chapter 4.
The major objective of new source performance standards is to obviate future
air pollution problems rather than to correct them after the fact. The most practical
time, from both an economic and technical viewpoint, to install pollution control
equipment is during the construction phase of a new facility. Add-on systems or
devices are more costly than those incorporated in the plant design, and they may not
represent the application of the best technology due to constraints placed on them by
existing structures and process considerations. Pollution control equipment, designed
as an integral part of a process or operation, is the most effective means of reducing
emissions at the least possible expense over add-on controls. New sources planned for
the use of coatings low in organic solvents will avoid delays in production as the
result of change-over from higher solvent systems avoiding economic benefits.
9.2. SELECTION OF POLLUTANTS AND AFFECTED FACILITIES
The pollutants for which New Source Performance Standards are being
prepared are airborne organic solvents emitted from stationary sources such as metal
furniture and fixture finishing lines.
9-2
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100% = 3,036 Plants
Percent
50
25 -
CD
I
CO
Figure 9-1. DISTRIBUTION OF 3000 PLANTS
MANUFACTURING METAL FURNITURE
-------
The metal furniture industry uses two types or organic solvent-borne
coatings: enamels and lacquers. Enamel is a type of paint consisting of an intricate
dispersion of pigments in a varnish or resin vehicle. The vehicle may be an oil-resin
mixture, or an entirely synthetic resin. The enamels containing drying oils are
converted to film by oxidation; those comprised wholly of synthetic resins may be
converted by either heat or oxygen or both.
Lacquers in contrast to enamels, do not undergo a chemical reaction when
exposed to heat. Applied lacquers are dried by evaporation of the solvent to form the
coating film.
The metal furniture industry uses organic solvent-borne coatings of quantity
estimated to be 279 million pounds in 1975. The most widely used resins in these
coatings are alkyd, others include acrylics, epoxies, polyesters, amines, vinyls and
cellulosics. The use of powder coatings is relatively small at this time. The organic
solvents used in coatings for metal furniture are aliphatics, xylene, toluene ketones,
and other aromatics. Solvents consumption of 170 million pounds annually in this
industry amounts to 6 percent of the total industrial coating solvent usage.
The functions of coatings in the metal furniture industry are corrosion
protection for the metal and esthetic decoration of the product. To provide these
functions, coating films must be continuous with good adherence to the surface and
they must be available in a variety of colors and glosses.
The process of finishing metal furniture may vary in detail from one plant to
another, however, there are many features common to all plants. The application of
coatings is done by spray coating, dip coating or flow coating. The process usually
involves the following steps. The parts to be coated, unassembled, sub-assemblies
and/or total assemblies, are loaded on a conveyor as they leave the metal fabricating
shop. The parts are conveyed through a cleansing and degreasing station to prepare
the surface for coating. These preparation steps are alkaline cleaning to remove light
mill scale and oils, hot water rinsing, iron phosphatizing bath or spray to improve
coating adhesion and prevent rusting during the process, and cold water rinsing. The
parts are dried by passing them through an oven at temperatures of 121 C to 177 C
(250°F to 350°C).
Some operations use a sandblasting chamber to remove mill scale, rust and
other dirt and do not use the washing step.
9-4
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The parts are next conveyed to the coating stations. Some parts, when
required, are prime coated by one of the spray techniques applied in a spray booth or
by dip or flow coating techniques. The spray booth, dip tank or flow coat nozzle
enclosure are vented to the atmosphere to eliminate accumulation of organic solvents
released from the coating.
The part is conveyed from the application station through an open area on its
way to the bake oven. The area called the flash-off area is often necessary to allow
time for the solvents in the coating to escape slowly from the wet film before it is
cured. This step in the process avoids blistering the film from entrapped solvents
during the bake cycle. This area is usually vented through roof fans.
The part is baked in an oven at temperatures ranging from 149°C to 204°C
(300°F to 400°F).
The topcoating is applied next. In some cases this coating is the only coating
applied when prime coats are not required. The topcoat is applied in a preferred
color and in some plants many color changes are made which are best applied by one
of the spray techniques. Flow coating and dip coating is usually restricted to the use
of one or two colors where changes are infrequent.
The part to be topcoated is conveyed through the spray booth as described in
the prime coat. In the case of dip coating and flow coating, conveyors carry multiple
parts on holding fixtures through the application station at high unit rates of
production.
Flash-off areas are in the process stream as previously described. The coated
parts are baked in an oven at temperature ranges of 149° C to 232°C (300°F to 450°F).
A touch-up area may be located at the end of a line where repair of coatings
is made. This work is usually done by spray application and air drying.
The affected facilities in the metal furniture coating lines are the coating
application station such as a spray booth, dip tank or flow coating station which
includes the flash-off area, and the curing station or bake oven or air drying location.
The latter is used when ovens are not required. The touch-up area may not be
considered an affected facility as the volume of solvents involved is expected to be
very low.
9-5
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The technology for controlling emissions at affected facilities was studied by
visiting plant sites and gathering information from other metal coating operations.
Emission reduction capabilities of various techniques and systems were compared for
cost effectiveness. These systems are tabulated in Chapter 8.2. Such systems were
selected for study on the basis that the technology to implement them was available
or demonstrated to be in use in the industry or related metal fabricating industries.
Emission reduction capability of add-on controls or coating systems, when compared
to a model base case plant using organic solvent-borne coatings, ranges from 22
percent to nearly 100 percent.
The cost analysis of systems with these capabilities of emission reduction
included all direct and indirect manufacturing costs, including an allowance for
capital investment depreciation with interest charges on the capital. These emission
reduction systems are based on two model plants scaled to produce, at an annual rate,
3,000,000 square feet and 22.4 million square feet of coated furniture. The smaller
capacity plant model utilizes a spray application system and the larger plant model is
a dip coating operation.
Cost effectiveness is measured in terms of annulized cost per metric ton of
organic solvent emissions controlled. Energy effectiveness is measured in terms of
British Thermal Units (BTUs) per metric ton of reduced emissions. Comparative
values for control options studied are shown in Table 9.2-1 for a model operation
using spray coatings and in Table 9.2-2 for a model operation using dip coatings.
The metal furniture industry organic solvent usage is estimated to be 80
thousand metric tons in 1976. The protected industry growth rate average per year is
3.8 percent for the period 1973 to 1980 and 3.3 percent for the period 1980 to 1985.
If no controls on the discharge of organic solvents in the air are used over the growth
forecast the organic solvent discharge could increase by approximately 37 percent in
1985 over the base year 1976. Fortunately, technology does exist that offers a means
to reduce these emissions over the years to be applied to new or significantly
modified sources as they become available each year in the industry.
9-6
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Table 9.2-1. COMPARATIVE ENERGY AND COSTS
OF POLLUTION CONTROL SYSTEMS
FOR SPRAY COATING OPERATION
Code
A-5
A-4
A-6
A-3
A-2
Case
Powder coating
High solids coatinga
Water-borne coating
Base
Carbon adsorber
on spray booth
Incinerator on cure
oven
Total
Energy Usage
106BTU
3,055
3,345
3,359
4,495
4,867
6,743
Percent
Increase or
(Decrease)
Over Base
(32)
(26)
(25)
—
8
50
Ratio BTUxlO"
Per Metric Ton
of Reduced
Emissions
178
235
251
—
420
1,728
Cost
$/Metric Ton
Reduced
Emissions
261
nil
2,195
—
2,374
3,110
A-7 Carbon adsorber on
spray booth and in-
cinerator on oven
7,417
65
482
2,576
Estimated on high solids, 80 percent solids/volume coating used in a metal furniture.
Reference 1 in Chapter 8.2. Costs are lower in energy use and floor space.
9-7
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Table 9.2-2. COMPARATIVE ENERGY AND COSTS
OF POLLUTION CONTROL SYSTEMS
FOR DIP COATING OPERATION
Code
Case
Percent
Total Increase or
Energy Usage (Decrease)
106BTU Over Base
Ratio BTUxlO
Per Metric Ton
of Reduced
Emissions
Cost
$/Metric Ton
Reduced
Emissions
B-6 Water-borne dip
coating 5,027
B-l Base 7,244
B-3 Solvent-borne dip
coating, carbon ad-
sorber on dip tank
B-2 Water-borne coating
electrodeposition
B-4 Incinerator on
cure oven
B-5 Carbon adsorber on
dip tank and in-
cinerator on oven 12,119
(31)
68
630
7,390
7,778
11,163
2
7
54
149
91
338
502
45
1,052
67
147
722
9-8
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9.3. SELECTION OF THE BEST SYSTEM OF EMISSION
REDUCTION CONSIDERING COSTS
(To be prepared by EPA.)
9-9
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9.4. SELECTION OF THE FORMAT OF THE PROPOSED STANDARD
The format for writing a standard is needed to uniformly measure
performance of compliance to that standard. The term "format" is defined, for the
purposed ot this Chapter, as a ratio of emissions to a prescribed unit. The format
could be chosen from any of the following approaches: concentration, mass/time,
mass/unit of production, equipment standard, or mass/unit of coating material
consumption. Each of these approaches has advantages as well as some disad-
vantages; however, most provide no long-range incentive to the user for energy
reduction as required to abate emissions.
A brief discussion of each of these approaches will indicate why the best format
for a standard is based on the mass/unit of coating material consumption.
9.4.1. Concentration - Airborne Emissions
The standards written in terms of concentration allowable in parts per million
or whatever units by definition would govern the quantity of organic emissions
discharged from the affected facility in terms of the quantity of air exhausted to the
atmosphere from the affected facility. To enforce this format-standard would
require constant monitoring of the discharge, which can be done with present
technology. However, to reduce significantly the organic emissions from solvent-
borne coatings, the use of add-on control equipment such as carbon adsorbers or
incinerators is required. This is also possible within the present technology.
For compliance, another alternative would be to change coating formulation;
but unless organic solvents were significantly reduced, the emission problem would
persist.
The reduction in the use of energy by means of add-on controls required to
abate organic emissions would most likely take place over a long period of time. This
constitutes an indirect approach to the long-range solution of the organic emission
problem.
9.4.2. Mass/Time - Airborne Emissions
This format suggests that a limitation be placed on the mass of organic
emissions from an affected facility within a time period which is now in use within
many states and localities within the states. The format is enforceable and requires
monitoring equipment, as stated above. Also, add-on equipment involving the same
9-10
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energy excesses for total abatement will be required to abate emissions from organic
solvent-borne coatings. This format, as with the previous one, does not get at the
root of the problem of providing an incentive to reduce the use of organic solvents
and thinners in the coating.
9.4.3. Equipment Standard - Airborne Emissions
This format suggests that equipment used in the coating process be designed
to meet an emission limitation. The burden of this requirement would fall on the
equipment manufacturer, who probably could not comply without qualifying the type
of coatings to be used with such equipment. The performance of the coating would
dictate its selection by the end user, and the equipment manufacturer would want to
place restrictions that would probably not be compatible with the performance of the
coating. An unwieldy situation would develop and, as in the previous formats
discussed, the long-range aspects of energy reduction in emission abatement would
not be directly approached.
9.4.4. Mass of Emissions/Unit of Coating Material Consumed
The standards written in the format of liters or kilograms of organic
emissions per liter of coating materials used by an affected facility is the most direct
approach to a long-range solution to the problem of control of organic emissions from
stationary sources. A programed approach to the 'application of this format to the
industry will consider present technology availability in coatings. Each year or
designated period the emission standards may be made more stringent according to a
program for the industry to reduce emissions over a reasonable length of time. As a
matter of interest graphic presentation of the effect on emission reduction through
the use of higher solids coatings will be found in Chapter 4 - Emission Control
Techniques - Figure 4-11, page 4-48
The energy consumption for emission abatement from present organic
solvent-borne coatings will increase over the short-term in new stationary sources
that must comply with performance standards. The use of incineration or adsorption
techniques may have to be considered until higher solids coatings are used. The
pressure to provide high solids coatings will be on the coating manufacturer who will
respond to the industry. In the long-term, there will be in effect the incentive to use
coatings with less volatiles in order to reduce energy costs of emission abatement.
9-11
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There are some areas where some interpretation will be required in the use of
this format. Also the format does not take into account volatile organic emissions
caused by the reaction products during the curing of the coating, however, coating
manufacturers may be able to supply this data.
A limitation of this format is possible under conditions where a coating
facility is converted from, as an example, a conventional spray system to an
electrostatic spray system improving transfer efficiency of the coating operation
thereby using less coating material over a time interval resulting in less emissions.
Another example of a limitation of this format would be when a different coating is
used having better hiding power resulting in the use of thinner coating say changing
1.2 mils to 0.8 mils thickness. There is definitely a percentage reduction of organic
emissions possible in these two examples that would not be recognized in this format.
The latter case may be more prevelant in the modified or reconstructed facilities.
For the cases found in new sources and the majority of modifications
reconstructions, the format will provide a straight forward means of measuring
organic solvent emissions. The format will be easily measurable at the source, and
the quantities of coating, volatiles, or organic solvents used per time period can be
reported by the user and trade organizations. Routine monitoring tests and plant
surveys will confirm compliance with new source performance standards.
9-12
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9.5. SELECTION OF EMISSION LIMITS
(To be prepared by EPA.)
9.6. VISIBLE EMISSION STANDARDS
(To be prepared by EPA.)
9-13
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9.7. MODIFICATION/RECONSTRUCTION CONSIDERATION
Modifications and reconstructions are discussed in Chapter 5 and are repeated
here.
Proposed standards apply to all affected facilities constructed or modified
after the date of proposal of the proposed standards. Provisions applying to
modification and reconstruction were originally published in the Federal Register on
December 23, 1971. Clarifying amendments were proposed in the Federal Register on
October 15, 1974 (39 FR 36946), and final regulations were promulgated in the
Federal Register on December 16, 1975 (40 FR 58416).
Modification is defined as "any physical change in, or change in the method of
operation of, an existing facility which increases the amount of any air pollutant (to
which a standard applies) emitted into the atmosphere by that facility or which
results in the emission of any air pollutant (to which a standard applies) into the
atmosphere not previously emitted". Reconstruction occurs when components of an
existing facility are replaced to such an extent that:
(1) The fixed capital cost of the new components exceeds 50
percent of the fixed capital cost that would be required to
construct a comparable entirely new facility, and
(2) It is technologically and economically feasible to meet the
applicable standards.
There are certain circumstances under which an increase in emissions does not
result in a modification. If a capital expenditure that is less than the most recent
annual asset guideline repair allowance published by the Internal Revenue Service
(Publication 534) is made to increase capacity at an existing facility and also results
in an increase in emissions to the atmosphere of a regulated pollutant, a modification
is not considered to have occurred.
An increase in working hours - i.e., from one to two-shift operation - or an
extension from 8 hours to 10 hours per shift would also increase solvent emissions per
day. This situation, however, is also not considered a modification under the
definitions set forth in 40 FR 58416, December 16, 1975.
9-14
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The purpose of this Chapter is to identify potential modifications and
reconstructions of affected facilities, and any exemptions or special allowances
covering changes in existing facilities that should be considered. Exemptions from
the regulations may be based on availability of technology and economic considera-
tions.
As will be seen, many of the possible changes do not qualify as modifications
by strict definition. They are, however, potential causes of increased solvent
emission and as such should be discussed.
9.7.1. Potential Modifications
The following changes in materials or formulations could cause increased
solvent emissions but would qualify primarily as alternate raw materials, not as
modifications, under the above definition unless capital expenditures are required to
effect the change so as to qualify as a reconstruction.
(1) Lower Solids Coatings
If a change is made from a higher solids to a lower solids coating-
e.g., from an enamel to a lacquer - more material, hence more solvent,
will be used to maintain the same dry coating thickness. While a change
in the direction of lower solids is unlikely, it could occur in any one
plant as a result of changing paint systems or colors. It is unlikely,
however, that any major capital expenditures to equipment would be
required.
(2) Use of Higher Density Solvent
Regulations normally restrict the number of pounds of solvent
which can be emitted. A change in the density of the solvents used,
even if the volumetric amounts used were the same, would result in
more pounds or kilograms being emitted. Again, this could be construed
as a raw-material substitution and hence not a modification, as no
major capital expenditures would be involved. Such substitutions might
come about as a result of solvent shortages, attempts to cut paint costs,
or efforts to incorporate less photoreactive solvents.
9-15
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(3) Increased Thinning of Coatings
A change to a higher viscosity coating could result in an increased
use of solvents for thinning the coating to proper application consis-
tency.
While these three cases can be considered as raw material substitutions, they
are not of themselves considered to be modifications. The phrase "bubble concept"
has been used in Title 40 FR 58416, to refer to a trade-off of emission increases from
one facility undergoing a physical or operational change with emission reductions
from another facility in order to achieve no net increase in the amount of any air
pollutant (to which a standard applies) emitted into the atmosphere by the stationary
source as a whole.
Title 40 FR 58416 states: "In those cases where utilization of the exemptions
under Paragraph 60.14 (e) (2), (3), or (4) as promulgated herein would effectively
negate the compliance measures originally adopted, use of those exemptions will not
be permitted."
Other changes that could be made that could result in increased solvent
emission include:
(4) Change to Larger Parts
If part sizes were increased and the same production rates were
maintained, more coating materials would be used. With the diversity
of products produced by the metal furniture industry, it is somewhat
difficult to see why this could occur unless a manufacturer began
production of large parts such as desks or panels that he had not
produced before.
Coating lines in this industry, however, are generally equipped to
handle many size parts hence such a change would not qualify as a
modification per se. If extensive capital expenditures were involved,
such a change could be classified as a reconstruction.
9-16
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(5) Change to Thicker Coatings
A change to a thicker coating, other factors remaining constant,
could result in increased solvent emission. Such a change could result
from a desire to increase durability or resistance to outdoor exposure.
Most metal furniture manufacturers, especially of office furniture,
apply as thin a coating as possible, however.a
(6) Reduced Deposition Efficiency
Increased overspray because of a process modification such as a
switch from electrostatic spray to conventional spray would result in
increased emission. For economic reasons if for nothing else, however,
a switch in such a direction is unlikely except possibly as a temporary
measure.
(7) Additional Coating Stations
If for any reason additional coating stations were added, emissions
would be increased. It is possible that new paint systems could result in
such a change. This could involve a reconstruction or a new facility
and, as such, would be subject to regulation.
9.7.2. Substitution of Equipment
There can be cases where in existing sources coating line configurations are of
a temporary nature to perform custom jobs. Certain custom coaters in this metal
furniture industry perform metal coating services only. These services are offered to
metal furniture manufacturers on a contract basis. In the course of this type of
business the coating line configuration may be changed to meet requirements of a
specific contract job. For example, existing coating line components such as spray
booths and dip tanks may be interchanged to accomodate different jobs. Another
example, existing ovens may be lengthened or shortened for each job. The
aforementioned changes do not constitute a modification. It is the intent to allow the
custom coater to make changes of this nature for short-term contract business
without invoking compliance with new source performance standards.
Installation of a line or affected facility previously used at another plant site
however will require compliance to new source performance standards.
a Chapter 5
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9.7.3. Reconstruction
Spray booths and bake ovens used in coating metal furniture last ten to twenty
2
years and are not replaced before that time unless process changes dictate it. In
some cases a line may be moved to another location within the plant and booths or
ovens may fall apart necessitating some rebuilding.
Reconstructions would include replacement of spray booths either because of
deterioration or because of more advanced design such as the addition of more
automatic spraying or electrostatic spraying, if not already being used.
A line could be made longer or faster to permit increased production. This
would be considered a reconstruction as long as the requirements outlined in the
beginning of this chapter are met.
Ovens could be replaced with more efficient models or to accomodate new
energy sources such as electricity.
Changing coating application methods such as from dip coating to electrostatic
spray would qualify as a reconstruction, again if requirements were met.
It should be noted that according to 40 FR 58416 that an existing facility, upon
reconstruction becomes an affected facility and hence subject to regulation
irrespective of any change in emission rate.
It should also be noted that according to 40 FR 58416, Part 60, the decision as
to whether a reconstructed facility can meet applicable standards both technologic-
ally and economically rests with the EPA Administrator. For example, if the
equipment being replaced does not emit air pollutants, it may be determined that
controlling the components that do emit air pollutants is not reasonable considering
cost, and standards of performance for new sources should not be applied. As another
example, if there is insufficient space after the replacements at an existing facility
to install the necessary air pollution control system to comply with standards of
performance, then reconstruction would not be determined to have occurred.
9.7.4. Constraints
Probably the greatest physical constraint to switching to new coating systems
with lower solvent emissions is the added space requirements of some of the systems.
The seriousness of this constraint will, of course, vary from line to line or plant to
9-18
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plant. Plants with very tight space requirements might find it difficult to fit in the
longer oven and flash-off area required by water-borne spray systems. Electrodeposi-
tion tanks are long to allow the necessary immersion time and rinse area.
Add-on controls for controlling bake oven emissions such as incinerators are
relatively small and usually can be mounted on top of the oven. It could be difficult
if space were tight to find room for a large carbon adsorber to handle spray booth
emissions.
Incinerators, especially if used for controlling spray booth emissions, use a
great deal of fuel even with heat recovery. This constraint is considered very
sensitive in this era of energy shortages.
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9.8. SELECTION OF MONITORING REQUIREMENTS
(To be prepared by EPA.)
9.9. SELECTION OF PERFORMANCE TEST METHODS
(To be prepared by EPA.)
9-20
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APPENDIX A. EVOLUTION OF PROPOSED STANDARDS
June 27. 1975
EPA authorized Springborn Laboratories, Inc. (formerly DeBell <5c Richardson,
Inc.) to conduct an Air Pollution Control Engineering and Cost Study on the General
Surface Coating Industry including the Metal Furniture Industry. Springborn
Laboratories Program Manager: Dr. Bernard Baum. EPA Contract Project Officer:
David Patrick.
August 11, 15, 20, 1975
Springborn Laboratories conducted an equipment survey to review coating
equipment, contacting manufacturers by telephone.
August 25, 1975
Springborn Laboratories visited Nordson Corporation in Amherst, Ohio to
discuss powder coating application in the industrial coating industry.
August 27, 1975
Springborn Laboratories visited Interred Corporation in Stamford, Connecti-
cut to discuss powder coating technology and equipment.
August 28, 1975
Springborn Laboratories met with EPA representatives in Durham, North
Carolina, to discuss progress of the study.
September 26. 1975
Office of Management and Budget approved the EPA questionnaire for
distribution in the industrial finishing industry.
January 28, 1976
Springborn Laboratories visited the Simmons Company plant in Munster,
Indiana to observe the high solids coating operation and to obtain related data.
February 11, 1976
Springborn Laboratories visited Virco Manufacturing Corporation plant in
Gardena, California. The purpose of the visit was to observe a powder coating metal
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furniture line and a solvent coating metal furniture line with an incinerator. Data on
powder coating operations were obtained.
February 24, 1976
Springborn Laboratories visited the Steelcase Company plant in Grand Rapids,
Michigan to observe the metal furniture coating operation. Information on powder
coating was obtained.
March 8, 1976
Springborn Laboratories visited Goodman Brothers Manufacturing Company
plant in Philadelphia, Pennsylvania to observe the powder coating operation.
March 8, 1976
Springborn Laboratories visited the Bunting Company plant in Philadelphia,
Pennsylvania to observe the powder coating of outdoor household furniture.
Information on powder coating was obtained.
March 12, 1976
Springborn Laboratories visited Lyon Metal Products, Inc. plant in Aurora,
Illinois to observe the solvent-borne coating of metal office furniture and to collect
related data.
April 2, 1976
Springborn Laboratories visited Herman Miller, Inc. plant in Zeeland,
Michigan. The purpose of the visit was to observe the powder coating operation of
metal furniture and to obtain related data.
April 5, 1976
Springborn Laboratories visited Angel Steel Company plant in Plainwell,
Michigan to observe the electrodeposition coating operation for metal furniture and
to obtain related data.
April 6, 1976
Springborn Laboratories visited U.S. Furniture Industries, Blacksmith Shop
Division in Highpoint, North Carolina to observe the powder coating operation of
metal furniture.
A-2
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April 21, 22, 23. 1976
Springborn Laboratories attended Chemical Coatings Conference in Cincin-
nati, Ohio.
September 26. 1976
Springborn Laboratories visited Georg Koch <5c Sons, Inc., Evansville, Indiana
to review available finishing technology.
July 15, 1976
The first interim report on Air Pollution Control Engineering and Cost Study
of the Surface Coating Industry was sent to EPA, Triangle Park, North Carolina.
Metal Furniture Coating Industry was included.
August 23, 1976
The second interim report on Air Pollution Control Engineering and last study
of the Surface Coating Industry was sent to EPA, Triangle Park, North Carolina.
Metal Furniture Coating Industry was included.
May 19, 1977
Springborn Laboratories met with EPA in Triangle Park, North Carolina to
discuss general surface coating projects.
June 14, 1977
Springborn Laboratories was authorized to continue and complete the study to
support New Source Performance Standards for metal furniture coating.
August 23, 1977
Springborn Laboratories made a telephone survey to resin suppliers to discuss
present status of high solids coating for metal furniture.
August 25, 1977
Springbom Laboratories made a telephone survey to resin suppliers to discuss
present status of powder coatings and water-borne coatings for metal furniture.
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APPENDIX B. INDEX TO ENVIRONMENTAL IMPACT CONSIDERATIONS
Agency Guidelines for Preparing Regulatory
Action Environmental Impact Statements
(39 FR 37419)
Location Within the Standards Support
and Environmental Impact Statement
Background description of the domestic
metal furniture industry (number of plants,
location, production, trends, etc.).
General procedures, basic processes.
Processes or facilities and their emissions
Affected facilities and types of sources.
Modifications and reconstructions.
Emission control technology.
Environmental impacts of suggested alterna-
tive control systems.
Chapter 3, pages 3-1 through 3-4. Data
are found also on pages 7-1 and 7-2.
Chapter 3, Sections 3.2.1.1 and 3.2.1.2;
pages 3-5 through 3-13.
Chapter 3, Section 3.2.3; pages 3-15
through 3-16.
Chapter 4, Sections 4.1.1 through 4.2.8;
pages 4-1 through 4-49. Chapter 9,
Section 9.1. and 9.2; pages 9-1 through 9-8.
Chapter 5, pages 5-1 through 5-5.
A discussion of the alternative emission
control systems and their effectiveness
is presented in Chapter 6; pages 6-1
through 6-13.
The various relationships between these
alternatives are tabulated in Tables 6-1,
and 6-2; pages 6-2 and 6-3.
Flow diagrams illustrating these alterna-
tive systems are presented in Figures 6-1
through 6-7; pages 6-5, 6-6, 6-8 through
6-10, 6-12 and 6-13.
A discussion of the suggested alternative
control systems is presented in Chapter 7.
Estimated hydrocarbon emission reduction
in future years is discussed in Section 7.1.3.
These are shown also in a tabulated form for
1976 through 1985 in Tables 7-3 through 7-8;
pages 7-11 through 7-16.
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Agency Guidelines for Preparing Regulatory
Action Environmental Impact Statements
(39 FR 37419)
Location Within the Standards Support
and Environmental Impact Statement
Secondary impacts associated with the
suggested alternative control systems.
Other environmental impacts and concerns.
Extension of time and effective date of
standards.
Energy requirements for alternative
control systems.
Economic impacts of alternative control
systems.
Capital and operating costs for alternate
control systems
Affected facilities and energy requirements.
Cost effectiveness for emission reduction
State regulations and controlled emissions.
Uncontrolled emissions.
Secondary impacts are discussed under
Chapter 7, Section 7.2 (water); pages 7-17
through 7-18. Section 7.3. (solid waste dis-
posal); pages 7-18 through 7-20. Section 7.4.
(energy); pages 7-20 through 7-22.
Tables 7-9 and 7-10 show energy balances and
energy requirements of the various suggested
alternative control systems.
Chapter 7, Sections 7.5 and 7-6 discuss impacts
other than primary and secondary impacts
associated with the suggested alternative con-
trol systems; pages 7-23 and 7-24.
Chapter 7, Sections 7.6.2 and 7.6.3, deal with
impacts of delayed and no standards; pages
7-23 and 7-24.
Chapter 7, Section 7.4, Tables 7-9 and 7-10
show energy balances in tabulated form;
pages 7-21 and 7-22.
Chapter 8, Section 8.1 and 8.2; pages 8-1
through 8-38.
Chapter 8, Section 8.1 and 8.2; pages 8-1
through 8-38.
Chapter 9, Section 9.2; pages 9-2 through
9-8.
Chapter 9, Section 9.
Chapter 7, Section 7.1.1, pages 7-3 through
7-5.
Chapter 7, Section 7.1.2; page 7-5.
B-2
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TECHNICAL REPORT DATA
(Please read Instructions on the reverse before completing)
1. REPORT NO.
EPA-450/3-78-006
2.
3. RECIPIENT'S ACCESSION* NO.
TITLE ANOSUBTITLE
tudy to Support New Source Performance Standards for
iurface Coating of Metal Furniture
5. REPORT DATE
April 1978
6. PERFORMING ORGANIZATION CODE
7. AUTHOR(S)
8. PERFORMING ORGANIZATION REPORT NO.
Springborn Laboratories, Inc.
9. PERFORMING ORGANIZATION NAME AND ADDRESS
Springborn Laboratories, Inc.
Enfield, Connecticut 06080
(Formerly DeBell & Richardson. Inc.}
10. PROGRAM ELEMENT NO.
11. CONTRACT/GRANT NO.
EPA 68-02-2075
12. SPONSORING AGENCY NAME AND ADDRESS
Environmental Protection Agency
Office of Air Quality Planning & Standards
Emission Standards & Engineering Division
Research Triangle Park. N.C. 27711
13. TYPE OF REPORT AND PERIOD COVERED
Final
14. SPONSORING AGENCY CODE
200/04
15. SUPPLEMENTARY NOTES
16. ABSTRACT
The purpose of this report is to provide the information for EPA to establish
Standards of Performance for New Stationary Sources under Section 111 of the
Clean ^Air Act as amended. Included are descriptions of the industry, organic
emission control techniques and their costs.
17.
KEY WORDS AND DOCUMENT ANALYSIS
DESCRIPTORS
b. IDENTIFIERS/OPEN ENDED TERMS
c. COSATI Field/Group
Air Pollution Control Equipment
Hydrocarbons
Organic Solvents
New Source Performance Standard
Metal Furniture, Surface Coating
Paint
Air Pollution Control
Stationary Sources
Hydrocarbons
Organic Solvent Emission
Control
t
DISTRIBUTION STATEMENT
Unlimited
19. SECURITY CLASS (ThisReport)
Unclassified
21. NO. OF PAGES
212
20. SECURITY CLASS (Thispage)
Unclassified
22. PRICE
EPA Form 2220-1 (9-73)
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