i453R98009D
National Emission Standards for Hazardous Air Pollutants
(NESHAP) for the Aerospace Manufacturing and Rework Industry
Background Information for Promulgated Standards
ADDENDUM
Julv 1998
NESHAP
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National Emission Standards For Hazardous Air Pollutants
(NESHAP) for the Aerospace Manufacturing and Rework Industry
Background Information for Promulgated Standards
ADDENDUM
Emission Standards Division
U S ENVIRONMENTAL PROTECTION AGENCY
Office of Air and Radiation
Office of Air Quality Planning and Standards
Research Triangle Park, North Carolina 27711
July 1998
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ENVIRONMENTAL PROTECTION AGENCY
National Emission Standards for Hazardous Air Pollutants from
the Aerospace Manufacturing and Rework Industry —
Background Information for Promulgated Standards
Prepared by:
Bruce C. Jordan (Date)
Director, Emission Standards Division
U. S. Environmental Protection Agency
Research Triangle Park, NC 27711
1. The final National Emission Standards for Hazardous Air Pollutants (NESHAP) will regulate
emissions of hazardous air pollutants from cleaning operations; primer, topcoat, and chemical
milling maskant application operations; depainting operations; and handling and storage of
waste at aerospace manufacturing and rework facilities. Only those operations that are part of
major sources under section 112(d) of the Clean Air Act as amended in 1990 will be
regulated.
2. Copies of this document have been sent to the following Federal Departments: Labor, Health
and Human Services, Defense, Transportation, Agriculture, Commerce, Interior, and Energy;
the National Science Foundation; and the Council on Environmental Quality; members of the
State and Territorial Air Pollution Program Administrators; the Association of Local Air
Pollution Control Officials; EPA Regional Administrators; and other interested parties.
3. For additional information contact:
Ms. Barbara Driscoll
Policy Planning and Standards Group (MD-13)
U.S. Environmental Protection Agency
Research Triangle Park, NC 27711
Telephone: (919) 541 -0164
4. Paper copies of this document may be obtained from:
National Technical Information Service (NTIS)
5285 Port Royal Road
Springfield, VA 22161
Telephone: (703) 487-4650
U. S. EPA Library Services Office (MD-35)
U. S. Environmental Protection Agency
Research Triangle Park, N.C. 277111
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5. Electronic copies of this document may be obtained from the EPA Technology Transfer
Network (TTN). The TIN is an electronic bulletin board system which is free, except for the
normal long distance charges. To access the aerospace BID
Set software to data bits: 8, N, stop bits 1
Use access number (919) 541-5742 for 1200, 2400, or 9600 bps modems [access
problems should be directed to the system operator at (919) 541-5384].
Specify TTN Bulletin Board: Clean Air Act Amendments
• Select menu item: Recently Signed Rules
IV
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TABLE OF CONTENTS
Page
1 0 SUMMARY 1-1
2 0 COMMENTS 2-1
2 1 DEFINITION OF GENERAL AVIATION 2-1
2 2 STANDARDS FOR PRIMERS AND TOPCOATS 2-1
2 3 DEPAINTING STANDARDS 2-4
2 4 CLARIFICATION OF RELATIONSHIP BETWEEN
NESHAP AND FAA REGULATIONS 2-6
2 5 EXEMPTION FOR CLEANING OF AUTOMATED SPRAY
EQUIPMENT NOZZLE TIPS 2-9
2 6 MONITORING PARAMETERS FOR PUMPLESS WATERWASH
SYSTEMS 2-9
2 7 EXCLUSION OF CHARGED MEDIA CERTIFICATION
USING TEST METHOD 310 . . . ... 2-9
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1.0 SUMMARY
On September 1, 1995, the U. S Environmental Protection Agency (EPA) promulgated
national emission standards for hazardous air pollutant (HAP) emissions from major sources in
the aerospace industry (60 FR 45948). These final standards implemented Section 112(d) of the
Clean Air Act as amended in 1990 (the Act) Amendments to the final rule were promulgated on
March 27, 1998 (63 FR 15006). Also on March 27, 1998, the EPA proposed additional
amendments to the final rule (63 FR 15034) Nineteen comment letters (see Table 1-1) were
submitted by representatives from fifteen companies or organizations, consisting of general
aviation rework and manufacturing facilities, paint arrestor and filtration product manufacturers.
filter testing laboratories, major aerospace (equipment) manufacturers, and industry trade
associations Table 1-1 lists the commenters and their respective affiliations Summaries of the
comments and the EPA's responses are presented in this document, which serves as the basis for
the revisions (amendments) made to the final NESHAP This document is an addendum to
Volume II of "National Emission Standard for Hazardous Air Pollutants (NESHAP) for the
Aerospace Industry - Background Information for Promulgated Standards," July 1995, EPA
Document No EPA/R-97-003b (Docket A-92-20, item III-B-1)
The proposed amendments requested comments regarding the addition of definitions for
"General Aviation (GA)," and "general aviation rework facility"; a revised definition for
"waterwash system", alternative emission limits for topcoat and primer applications for GA
rework facilities; clarification of the relationship between NESHAP and Federal Aviation
Administration (FAA) regulations, removal of references to Section 112(1) of the Act for hand-
wipe cleaning and the equipment volume reduction demonstration, an exemption for cleaning of
automated spray equipment nozzle tips; clarification of the monitoring requirements for pumpless
waterwash systems, and the exclusion of charged media certification using Test Method 319.
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TABLE 1-1 LIST OF COMMENTERS ON THE PROPOSED AMENDMENTS TO
THE AEROSPACE NESHAP (63 FR 15034)
Item No. in
Docket A-92-20
Vl-D-01
VI-D-02
VI-D-03
VI-D-04
VI-D-05
VI-D-06
VI-D-07
VI-D-08
VI-D-09
VI-D-10
VI-D-11
VI-G-01
VI-G-02
VI-G-03
VI-G-04
VI-G-05
VI-G-06
VI-G-07
VI-G-08
Commenter, affiliation, and date
Keith P. Gutreuter, Air Technologies, Inc., Ottawa, KS. April 28, 1998.
George H Southland, Hazardous Material/Safety Specialist, Kal-Aero, Duncan Aviation,
Battle Creek, MI May 1 3, 1 998
James E Clifford, Vice President and Senior Executive Assistant, Kal-Aero, Duncan Aviation,
Battle Creek, MI. May 13, 1998
John M Ellis, III, President, Kal-Aero, Duncan Aviation, Battle Creek. MI May 13, 1998
Michael K Haufe, P.E , Columbus Industries, Inc., Asheville, OH Ma> 1 1, 1998
Tom Justice, Vice President of Operations, Purolator Products Air Filtration Company,
Henderson, NC May 21,1998
Glvnn Rountree, Director, Environment, Safety, and Health, Aerospace Industries Association,
Washington, D C May 26, 1 998
Cheryl Russell, Federal Affairs Director, Boeing Company, Arlington, VA Ma) 26, 1998
Charlie Johnson, President and COO, Cessna Aircraft Company, Wichita. KS Mav 19, 1998
Stephen P Risotto, E\ecuti\e Director. Halogenated Solvents Industry Alliance (HSIA), (via
e-mail) Ma\ 26. 1998
Andrew V Cebula. Vice President, National Air Transportation Association (NATA),
Alexandria, VA (\ia e-mail) May 25, 1998
Walter L Desrosier. Manager. Maintenance and Engmeenng, General Aviation Manufacturers
Association, Washington. D C Mav 26, 1998
Mark A Thompson. Environmental Specialist, Bombardier Aerospace Learjet Inc , Wichita.
KS Ma> 22. 1998
Al Vatine, Technical Representative, LMS Technologies, Inc , Edina. MN Mav 22, 1998
Gan G Maxwell. Division Administrative Coordinator, Atlantic Aviation Corporation.
Wilmington. DE Ma\ 27. 1998
Mark J Matthes, Vice President - Operations. Duncan A\iation, Lincoln. NE Ma\ 22, 1 998
Gan- Hartwig, General Manager, K-C Aviation, Appleton. WI. May 26, 1998
Duplicate entry of VI-D-10 (hardcopy of previously submitted e-mail comments)
Jim Burress, Paint Shop Crew Chief, Garrett Aviation, Springfield, IL Ma} 26, 1998
Comments were received on all of these issues except on the definition of "general aviation
rework facility", the removal of references to Section 112(1) of the Act for hand-wipe cleaning,
and the equipment volume reduction demonstration
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2.0 COMMENTS
2 1 DEFINITION OF GENERAL AVIATION
Comment Eight commenters (VI-D-02, VI-D-03, VI-D-04, VI-D-11, VI-G-04,
VI-G-05, VI-G-06, and VI-G-08) suggested that the definition of general aviation be changed to
read as follows "General Aviation (GA) means that segment of civil aviation that encompasses
all facets of aviation except air carriers, commuters, and military General Aviation includes
charter and corporate-executive transportation, instruction, rental, aerial application, aerial
observation, business, pleasure and other special uses " (Reference EPA Air Transportation
Industry Sector Notebook, EPA/310-R-97-001) Two commenters (IV-G-01 and VI-G-02)
agreed with the definition of general aviation provided in the proposed amendments. Commenter
IV-G-02 also agreed with EPA's statement that "the Agency believes that the proposed definition
for GA will accurately describe the segment of the aerospace industry servicing those smaller
aircraft for which the alternative primer and topcoat standards are intended "
Response The Agency has decided to change the definition of General Aviation as
suggested by the group of eight commenters The revised definition still accurately describes the
segment of the aerospace industry involving smaller aircraft for which the alternative primer and
topcoat standards are intended (See following Section 2 2 for specific comments and responses
related to the alternative standards for primer and topcoat application operations used at GA
rework facilities.) The revised definition also has the advantage (as noted by the commenters) of
being consistent with another recent EPA document addressing and describing this same segment
of the aerospace industry
2.2 STANDARDS FOR PRIMERS AND TOPCOATS
Comment Seven commenters (VI-D-02, VI-D-03, VI-D-04, VI-G-04, VI-G-05,
VI-G-06, and VI-G-08) agreed with the proposed alternative volatile organic compound (VOC)
limits for primer and topcoat applications on GA aircraft because they lift the restraints of the
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coating limitations The commenters noted that GA aviation aircraft rework is based on the
customer, the owner/operator specifies the acceptable quality, not the rework facility They
stated that the higher VOC limits are acceptable and encourage paint manufacturers to provide
quality primers and topcoats that give a quality finish acceptable to the owners/operators of the
aircraft
Commenter VI-G-04 noted that the higher VOC limits will have a minimal effect on the
total emissions from a facility, but will have a dramatic effect on the final aircraft topcoat finish.
The commenter noted that coating manufacturers have developed and are commercializing
excellent high solids products; however all technologies have their limits The commenter's field
experience indicates that this small VOC change will hasten the acceptance of superior coatings,
increased application latitude and efficiency and ultimately customer satisfaction and regulatory
compliance Although the commenter is not directly covered by the NESHAP, VOC/HAP
standards established in the NESHAP and control techniques guideline (CTG) and adopted by
their state limit the commenter's operations now The commenter currently complies with VOC
limits at 2 8 and 3 5 for primers and coatings, respectively The facility has been using compliant
primers (corrosion and sanding) applied with high-volume low-pressure (HVLP) equipment for
nearly a year with excellent results after a 2 to 3 month learning/training period However, the
commenter stated that compliant topcoat application has been more difficult, and a small increase
in the VOC limit will open the solvent combinations available and help to consistently produce a
beautiful finish for which the coatings are designed
Response The Agency appreciates the commenters' support on this issue and has
decided to finalize the alternative primer and topcoat limits as proposed.
Comment: Four commenters (Vl-D-07, VI-D-08, VI-G-01, and VI-G-02) agreed with
the increased VOC limits for primer and topcoat applications for general aviation (GA) rework
facilities, but the commenters suggested that these limits be extended to GA manufacturers as
well Commenter VI-D-07 argued that manufacturers have the same need for high quality finish
and may be put at a competitive disadvantage without the benefit of the higher limits
Manufacturers, if forced to abide with lower VOC and HAP limits for their paints, would lack the
increased painting operations flexibility that rework facilities would have and would not be able to
offer the best appearance available from their painting operations. Commenter VI-D-08 argued
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that differentiation between rework facilities and manufacturing facilities would establish an
obviously unfair business climate, with the advantage given to rework facilities in the case where a
manufacturer returns customer aircraft to the manufacturing factory for rework.
Commenter VI-D-07 noted that the number of GA manufacturing facilities that are
major sources for HAPs are less than the number of rework facilities that are major sources;
extending the higher limits to GA manufacturers should not greatly increase emissions and would
eliminate the competitive business advantage afforded to GA rework facilities under the proposed
amendment
Commenter VI-D-09 stated that the task of developing compliant coatings and strippers
has challenged manufacturers of GA aircraft who must find materials compliant with the
NESHAP, while enhancing the appearance of the aircraft and not jeopardizing the airworthiness
of the aircraft The commenter expressed concern that if rework facilities are allowed an alternate
standard as proposed, airworthiness certificates would be meaningless following rework of GA
aircraft
Commenter VI-D-02 stated that it would be a burden to expect their company to
differentiate between production and rework painting operations and to use different types of
coating for each operation The commenter stated that including manufacturing facilities would
more accurately reflect the Agency's stated intent to allow GA facilities to continue to provide the
type of world-class paint systems that their customers expect
Commenter VI-G-01 argued that the necessity to provide customer-specified coatings is
applicable for all stages of aircraft exterior finishing, both the first completing/outfitting paint job
as well as subsequent service depaint and repaint jobs It is not unusual for an aircraft to be
painted five to seven times during its lifetime, and the implication of the present definition is that
the first paint job on new U. S. manufactured GA aircraft cannot provide the appearance and
finish customers require The commenter stated that customers of GA aircraft manufacturers
deserve and pay for the same, if not better, quality than work performed at a rework facility; and,
differentiation between rework and manufacturing facilities would establish an unfair business
climate, with the advantage given to foreign aircraft manufacturers and rework facilities The
commenter noted that there are fewer than 10 GA manufacturers that would be considered major
sources
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Response: In considering these comments from GA manufacturers, the Agency noted
that such comments were not provided during the regulatory development process, nor were they
raised during any of the industry roundtable discussions During the last industry roundtable
discussions and prior to the proposed amendments, GA rework industry representatives stated
that rework facilities have to deal with a wide variety of coatings and aircraft (from all of the
different GA manufacturers), and client requirements on a time-critical basis. In comparing GA
manufacturing and GA rework painting operations, the Agency found that manufacturing facilities
typically deal with fewer types of coatings and fewer types of aircraft Each manufacturer
produces a limited subset of the planes on the market The GA manufacturers generally perform
rework only on planes that they manufacture; GA rework facilities, in contrast, may work on
planes from a variety of manufacturers Thus, unlike GA rework facilities, GA manufacturing
facilities have fairly predictable coating needs This allows manufacturers to be more proficient in
coating application and minimizes the variability of coating-related issues in their day-to-day
operations Because of these factors, GA manufacturers are better able than GA rework facilities
to comply with the coating limits in the NESHAP as originally promulgated The data collected
from the GA manufacturers during the past 2 years of the project indicated that several, if not
most, of the GA manufacturers are already using compliant coatings as part of their standard
manufacturing processes No additional technical data has been submitted to support the
commenters' argument for extending the alternative coating standards to GA manufacturers
Based on these comments and the information provided by the various industry segments
involving GA aircraft, the Agency has decided to finalize the primer and topcoat requirements as
proposed
2.3 DEPAINTING STANDARDS
Comment: Commenter VI-D-11 stated that the rework of GA aircraft is uniquely
customer driven The commenter noted that in the industry segment most affected by the
NESHAP, the owner/operator of the aircraft develops and maintains their own FAA-approved
maintenance instructions. In general aviation, the facility must follow the aircraft manufacturer's
instructions. The owner/operator of GA aircraft specifies the coating and acceptable quality of
the finish, not the owner/operator of the rework facility. The manufacturer of the aircraft
specifies what materials may be used to remove the coatings The commenter stated that the
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proposed amendments must address the manufacturer's prohibition against using NESHAP
compliant chemicals in the rework of GA aircraft.
Response The Agency does not believe that this issue is unique to the GA segment of
the aerospace industry. See Section 2.4 for additional discussion of the alternative solutions to
any aircraft manufacturer's prohibition against using NESHAP compliant materials for depainting
operations.
Comment Commenter VI-D-10 expressed concern that EPA has not proposed to
establish a separate MACT floor for depainting operations at GA maintenance facilities. The
commenter supported the Agency's proposal to establish separate VOC content limits for primer
and topcoat applications at GA rework facilities. However, in the absence of separate HAP limits
for depainting of these same GA aircraft, the commenter stated that EPA will be creating a "Catch
22" situation for rework facilities The commenter argues that the higher MACT floor for primers
and topcoats for GA maintenance is based on the application of thicker coatings on many GA
aircraft, yet. it is these thicker coatings that have severely limited the success of non-HAP
strippers in the GA market The commenter stated that the halogenated solvents industry has
submitted a significant amount of information to the Agency indicating that the alternative
strippers are not effective on coatings that are greater than 3 or 4 mils thick. In fact, the use of
non-HAP chemical strippers may make these coatings even more difficult to remove The
commenter argued that incomplete removal may create significant safety issues by preventing
thorough inspection of the aircraft surface
Because the coating that EPA is proposing to allow on GA will have to be removed, the
commenter suggested that EPA establish a separate MACT floor for depainting operations at GA
rework facilities Without a separate, more appropriate limit, those facilities subject to MACT
requirements for depainting may be put at a significant disadvantage when competing with the
majority of the industry that will not be required to comply with the NESHAP. Since these
smaller aircraft require considerably less stripper than commercial jets, the commenter suggested
that establishing a MACT floor for depainting of GA aircraft may be as simple as removing the
limitation on the use of HAP-based stripper formulations for spot stripping and decal removal
only
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Response The Agency does not agree with the commenter's argument. The final rule
as promulgated and subsequently amended includes a great deal of flexibility in the depainting
requirements. The alternative primer and topcoat limits for GA rework facilities allow different
coating formulations to be used in achieving the type of finish required by their customers on a
variety of aircraft from different manufacturers Manufacturers and rework operators are not
limited by the NESHAP in any way with regards to coating thickness.
The commenter's assertion that the alternative strippers are not effective on coatings that
are greater than 3 or 4 mils thick has also been argued against by several technical studies
documented during the development of the NESHAP where non-HAP and low-HAP chemical
strippers have been used effectively on GA and/or military aircraft with coating thicknesses in
excess of 10 mils The Agency has no technical justification for establishing a separate MACT
floor for depainting operations at GA rework facilities The compliance options for the spot
stripping and decal removal allowance are based on an average "per aircraft" annual HAP
(stripper) usage and provide additional flexibility to all depainting operations As defined in the
final rule, "spot stripping" means the depainting of an area where it is not technically feasible to
use a nonchemical depainting technique
2 4 CLARIFICATION OF RELATIONSHIP BETWEEN NESHAP AND FAA
REGULATIONS
Comment Seven commenters (VI-D-02, VI-D-03, VI-D-04, VI-D-11, VI-G-05;
Vl-G-06, and YI-G-08) suggested that chemicals that contain HAP required by the FAA
Airworthiness Directives (AD's) should be exempt The commenters stated that if, because of
aviation safety, the FAA cannot eliminate the use of a HAP in an AD, the use should be
considered exempt. Commenter VI-D-11 believes that the protection of the flying public must
take precedence over the minimal use of chemicals containing HAP's when used to correct a
known aviation hazard. Commenter VI-G-04 stated that airworthiness concerns should continue
to be foremost in all change evaluations This commenter encouraged continued cooperation
between the FAA and the EPA to resolve conflicting directives and regulations. One commenter
(VI-G-01) strongly suggested that the process to be identified by the FAA for the substantiation
of alternative means of compliance by repair stations and mechanics be addressed to specific
products. The commenter stated that the long-term impact of alternative chemical usage on
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various aircraft structures is not consistent across various products and manufacturers. A clear
statement is needed stating that an alternative to a HAP-restricted chemical identified by one
organization or manufacturer is not acceptable for use on another aircraft or product without
specific approval The commenter noted that this process is identical to that available to
certificate holders and is necessary to preserve safety and establish a commercial level playing
field
Response The EPA has continued to work closely with the FAA during the development
of the final NESHAP and the amendments to the NESHAP for the aerospace manufacturing and
rework source category. Both agencies recognize the importance of continuing airworthiness and
the safety of the flying public as repair facilities modify their procedures to comply with the
NESHAP The EPA is committed to minimizing the impact on airworthiness while maximizing
the reduction of HAP emissions under the NESHAP
Since promulgation of the NESHAP on September 1, 1995, many of the aircraft
manufacturers (principally those manufacturing transport category aircraft) have made the
necessary revisions to their maintenance manuals to provide for non-HAP materials (chemical
strippers) to be used for depainting Those revisions have been FAA approved or will be
submitted for FAA approval, when required For the other manufacturers (principally General
Aviation manufacturers), once the necessary information (revised/updated maintenance manuals,
service bulletins, and/or advisory circulars) is approved by the FAA and is distributed to the
regulated community, the potential regulatory conflict should be at a minimum, and aerospace
rework facilities will be able to use various products to comply with most EPA and FAA
requirements The EPA and FAA have agreed that the potential problems and issues raised by the
commenters can be and, in many cases already have been, resolved through the procedures
established in the existing regulations, and no further changes are needed to the NESHAP (except
for the exemption for those GA aircraft where the manufacturer is out of business which is being
addressed in these amendments — see following comment/response)
Should any manufacturers still in business not revise their maintenance instructions to
allow use of NESHAP-compliant materials, the FAA has committed to issue an advisory circular
publicizing the process by which repair facilities can request approval for alternatives. In addition,
many existing Airworthiness Directives (AD's), issued under part 39 of Title 14 of the CFR,
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specify the use of HAP (AD's are regulations addressing safety of flight, and compliance with
them is mandatory.) However, most AD's contain a provision for requesting an alternative means
of compliance. The FAA Notice N8100.13, "Alternative Means of Compliance (AMOC) for
Airworthiness Directives that Require the Use of Volatile Organic Compounds and/or Hazardous
Air Pollutants," (dated January 26, 1998), addresses the process by which repair stations,
mechanics and operators can obtain alternative means of compliance for other AD's for the
purpose of approving substitution of non-HAP materials.
Comment Commenter VI-D-10 agreed with EPA's proposal to exempt rework of
aircraft whose manufacturers are out of business and to provide a process for addressing existing
AD's The commenter noted that the AD's specify the use of methylene chloride-based strippers
for one reason—their proven effectiveness at removing built-up coatings and for allowing visual
inspection of aircraft skins for cracks or fissures The commenter stated that until alternatives
have been tested and proven to be at least equally effective, the EPA and the FAA should be
extremely cautious in approving any alternative means for compliance with existing AD's
requiring the use of methylene chloride-based strippers The commenter expressed concern over
the potential conflict if EPA prohibits methylene chloride-based strippers when the maintenance
manuals for those aircraft specify that only methylene chloride-based strippers may be used, this
conflict could jeopardize aircraft airworthiness.
Response The EPA has coordinated efforts with the FAA to identify other alternatives
that can be used and define those types of aircraft where the existing procedures (e g .
changes/revisions to maintenance manuals or AD's) would be difficult and/or burdensome to
implement. The resulting exemption for those aircraft where the manufacturer is no longer in
business addresses the only concern identified not adequately addressed by existing regulations
Since promulgation of the NESHAP, many of the aircraft manufacturers have made the necessary-
revisions to their maintenance manuals to provide for non-HAP chemical strippers to be used for
depainting Those revisions have been FAA approved or will be submitted for FAA approval,
when required. Because of the small numbers of aircraft affected and the considerable expense of
testing alternative materials for use on aircraft whose manufacturers are out of business, the
Agency decided to finalize the exemption for rework of aircraft whose manufacturers are out of
business—see § 63 741(f) of the amended final rule.
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2 5 EXEMPTION FOR CLEANING OF AUTOMATED SPRAY EQUIPMENT NOZZLE
TIPS
Comment Commenter VI-D-08 agreed with the proposed exemption for cleaning of
automated spray equipment nozzle tips. The commenter stated that under the present NESHAP
language, owners or operators are forced to disassemble the equipment for cleaning, which is
economically unreasonable
Response The Agency appreciates the commenter's support on this issue
2 6 MONITORING PARAMETERS FOR PUMPLESS WATERWASH SYSTEMS
Comment' Commenter VI-D-08 stated that it would be impossible for pumpless
waterwash systems to comply with the monitoring requirements of the NESHAP as currently
written. The commenter fully supported EPA's effort to address the unique challenges presented
by pumpless waterwash systems and encouraged EPA to adopt the proposed language changes as
soon as possible
Response The Agency appreciates the commenter's support on this issue and decided to
finalize the additional and revised recordkeeping and monitoring requirements as proposed.
2 7 EXCLUSION OF CHARGED MEDIA CERTIFICATION USING TEST METHOD 319
Comment In regard to the proposed exclusion of charged media certification under Test
Method 319, two commenters (VI-D-01 and VI-D-05) concurred with the proposed exclusion,
two commenters (VI-D-06 and VI-D-08) opposed the exclusion, and one commenter (VI-G-03)
suggested the Agency re-visit the issue and consider adding a new mechanism within Method 319
to evaluate paint arrestor performance after loading (and over a given time period) Due to the
technical arguments associated with the comments involving Method 319, most of the summary
comments from the individual commenters are included in the following paragraphs As a
manufacturer of paint arresters, as well as air filters and other filtration products, commenter VI-
D-05 does not believe that charged-fiber media are appropriate for use in aerospace MACT
filtration products for the following reasons. Typically, charged-fiber media display a higher
initial (i e., clean filter) efficiency than similar media not composed of charged fiber However,
the efficiency of charged-fiber media often decreases upon filter loading as the charged fibers
themselves become coated with paint, defeating their electrostatic feature. With some paints (i.e.,
those that hit the filter "wet"), this charge-dampening effect may be even more pronounced
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Conversely, noncharged-fiber media are generally at lowest efficiency when clean (i e., this
medium becomes more efficient as it is loaded with paint) Method 319 evaluates the initial
particle size dependent filtration efficiency of paint arresters over the particle diameter range from
0.3 to 10 micron. Therefore, noncharged-fiber media evaluated by Method 319 and found to
meet the fractional efficiency requirements (when clean) will probably also meet these standards in
the field during paint loading However, charged-fiber media that is evaluated by Method 319 and
found to meet the fractional efficiency requirements (when clean), may or may not meet these
standards in the field during paint loading.
Commenter IV-D-01 also supported the proposed amendment to exclude charged media
from certification based on factual test data which show that charged media has a high initial
atmospheric dust spot efficiency but decreases in efficiency as the filter is loaded with
contaminant The commenter enclosed copies of test reports on two pleated type air filters, one
using Electrete charged media and the other using a cotton/polyester blend of media. The test on
the charged media was discontinued due to rapid efficiency decline after loading 30 grams of test
dust into the filter The cotton/polyester filter showed an increase in efficiency as the filter was
loaded with dust, which is typical for noncharged media
Commenter VI-D-08 disagreed with the proposal to eliminate the use of Test
Method 319 to approve charged media filters The commenter argued that a decision by EPA to
withdraw Test Method 319, without a valid replacement or test results that prove the method is
invalid, is inappropriate and unfounded The commemer's company has invested roughlv Haifa
million dollars installing over 100 Purolator charged media filters in keeping with the 1996
proposal to use Test Method 319 to approve filters Replacement of these filters would be a
costly and time-consuming process Many of the filters are in specially designed booths used to
paint central fuel tanks, wings, radomes, or other odd-shaped pieces. The filter systems have
already been modified to accommodate the Purolator filters, and additional modifications would
be needed to accommodate other types of filters
The commenter also noted that test data from the only existing methods that measure
particle size, Test Method 319 and the proposed ASHRAE 52.2, show that the Purolator charged
media filter(s) meet the efficiency curves. The commenter noted that although the ASHRAE 52 2
test is only a proposal and is designed for a different type of filter, it is the only test available that
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is designed to demonstrate how filters perform for different particle sizes after multiple loadings
The commenter stated that the Purolator filters not only passed the test but showed increased
efficiency with additional loadings; furthermore, the pressure resistance differential in the test
indicated that the filters would have to be changed out before loadings could occur beyond the
parameters of the ASHRAE test.
Commenter VI-D-08 disagreed with the basis for EPA's decision—an indoor air ventilation
type filter designed to capture air particulates, not paint. The commenter believed that these
filters are not designed to capture paint and should not be used to determine whether filters
designed for paints will perform in the same fashion
Commenter VI-D-06 also opposed the exclusion of charged media certification under Test
Method 319 The commenter stated that charged media are currently in use in numerous
applications worldwide both for HVAC and paint arrestance The increased use of these media in
recent years is a result of improved "fine fiber" technology, as well as more economic methods of
production
As a manufacturer of both charged-fiber and conventional media filters, commenter
VI-D-06 stated that charged-fiber filters are preferred in applications where
1 High initial efficiencies and low pressure drops are required The commenter enclosed
a test report for a conventional uncharged product that was performance tested in accordance
with ASHRAE Standard 52 1 An 85 percent bag filter started out at a 62.1 percent efficiency,
climbing to 85 percent at the end of the life cycle, which is a typical scenario for a fibrous filter
relying on aerodynamic particle capture The problem of low initial efficiencies has been
overcome to a degree by using charged fibers to enhance filtration early in the life cycle of the
system until enough paniculate loading has occurred that conventional aerodynamic capture or
mechanical loading becomes the primary mechanism driving the efficiency. The commenter also
enclosed efficiency curves showing that this charged-fiber filter overcame much of the early
inefficiencies raising the initial efficiency to 83 7 percent However, after 1/4 to 1/3 of the useful
life, the same aerodynamic mechanisms are dominating the performance of this media as seen in
the uncharged filter, the efficiency curves at this point are very similar.
2 Coarser fibers are required to support heavy paniculate loading as in the case of a paint
over spray filter. The commenter enclosed copies of test results from four separate manufacturers
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showing that the performance of uncharged filters exhibit either a drop in the dust spot efficiency
(ASHRAE 52 1) and/or arrestance from the initial measurement of the clean filter. The
commenter attributed these results to weak fibers, poor fiber bonding, or a combination of both.
The result is a media web that is structurally unable to support the accumulated paniculate, hence
a drop in the efficiency or arrestance. In the case of some charged media, there may also be a
sudden drop in efficiency early in the life cycle of the filter; however, the deterioration in the
efficiency was more likely the result of the weak web structure, not the charge
3. Energy consumption or low initial pressure drops are critical factors in the design
and/or operation of a system. By starting out at a lower initial pressure drop, the charged-fiber
filter results in higher efficiencies within the operating parameters of certain critical systems.
The commenter's greatest concern is that one unsubstantiated comment has led to the
proposal to exclude charged-fiber arresters from Method 319 certification The commenter
believed that the conclusions in this case may have been made prior to complete substantiating
data to support such a statement The commenter noted the following problems associated with
these preconceptions
1. There is currently no test protocol for comparing the "nontypical filtration efficiency
curves" of charged media Nontypical performance would have to be defined as higher initial
efficiencies at lower pressure drops, which is the primary goal of those who design filtration
systems
2 The position favoring exclusion assumes that all charged medias perform similar!)
This commenter's experience is that several charged media have exhibited consistent premature
failure or unloading while others have performed exceptionally well (The commenter enclosed
test reports supporting this claim )
3. In almost all cases, the failures of charged-media filters could be pinpointed to weak
fiber structure and/or poor fiber bonding This type of failure or drop in efficiency can be seen in
charged medias, as well as conventional uncharged filters. (The commenter enclosed test reports
supporting this claim.)
4. A major issue not yet resolved by the broad exclusion of charge media is: How much
charge warrants exclusion? And, what is the proposed technique for measuring this charge? The
charge in this case is a static charge, which is applied as either a permanent charge during fiber
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formation or as a corona charge applied to the formed media web. The commenter noted that all
synthetic medias exhibit some static charge
5. The commenter that objected to charged media pointed to "the rapid accumulation of
paint over spray" as creating "nontypical filtration efficiency curves over short time periods."
Theoretically, if a scenario were to be presented to support performance degradation in charged
media it would be on an extended life filter of about 6 to 12 months in an application of extremely
small particle concentrations. However, in the specific application of paint arrestance, there are
high concentrations of larger particles (than typical ambient) and short life cycles The rapid
loading of the filters accelerate the aerodynamic or mechanical mechanisms of particle entrainment
as the fibers are being coated
6 The opposing comment refers to "nontypical filtration efficiency curves over short time
periods " Method 319 however does not deal with "short time periods" or any other time
periods It only measures the initial or "clean" efficiency of the filter and does not reflect what
occurs during the life of the product ASHRAE 52 2P and SAE 1669 measure performance over
the effective life of the filter
Commenter VI-D-06 stated that development of an extended Method 319, which would
measure performance at different points over the life of the filter, is critical The commenter
enclosed results from several tests that were initiated to ensure that the company's products were
performing to actual conditions in these applications, including products tested for two-stage and
three-stage compliance with Method 319 under worse-case scenarios Commenter VI-D-06
stated that any new technology is likely to represent "nontypicaF" performance if measured against
conventional products rather than written performance requirements The commenter suggested
that "nontypicaF in the case of charged-fiber media for paint over spray applications could be
defined as an improvement in performance, and exclusion of this or any other new technology
would relegate this industry to a selection of media that have essentially remained unchanged for
over twenty years
Commenter VI-G-03, an independent filter and paniculate testing firm with experience in
paint overspray filtration tests and full-scale Method 319 tests, stated that there are some new
hybrid types of media and filters that possess both mechanical and electrostatic properties which
generally have better filtration characteristics than other single- and multi-stage filters that are
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promoted only as either "mechanical" filters or "electrostatic" filters. The commenter believes
that the filtration and filter-life efficiencies of these hybrid "mechano-electrostatic" filters are
substantial enough that the Agency may do well to re-visit the issue of whether or not to test and
certify electrostatic filters under the protocol of Method 319.
The commenter stated that these new hybrid media are basically mechanical media with a
small amount of electrostatic charging of the media fibers, not so strongly charged as in standard
electrostatic media (filters). The commenter is aware of at least two competing, independent
manufacturing firms that have developed this type of product, made typically as second-stage or
third-stage filters With the new hybrid media, removal of paint and dust particles is accomplished
mainly by mechanical (physical) action, but when tested with KC1, electrostatic charge plays a
somewhat greater role that is most operative in the earliest phases of filter life The commenter
offered the following explanation
Typical "mechanical" filters get better with time, filtration (fractional efficiency) starts out
low, but as challenge particulates such as paint or dust build up on the fibers, the fractional
efficiency increases because the size of air passages between fibers is decreased With
conventional "electrostatic" filters, the opposite occurs, fractional efficiency starts out high, but as
challenge particles coat the fibers, fractional efficiency actually decreases because the static
charges are blinded and not enough particle coating has accumulated to restrict the air passage
ways Now, however, with hybrid "mechano-electrostatic" media, fractional efficiency starts out
high, increases over time, and has not been found to decrease What apparently occurs is thai
when new hybrid filters are first challenged with aerosols, the electrostatic charges readily attract
and trap the particles, quickly reducing the inter-fiber airways. Then, as particles build up on the
fibers and the charges are masked, the amount of coating already built up on the fibers is sufficient
to permit the filter to act chiefly as a mechanical filter with high particle removal characteristics.
While the data obtained in both Method 319 and chromate paint loading tests are
confidential, the commenter stated that both the multistage 319 fractional efficiency and the paint
removal efficiency results using these new hybrid filters are better than that obtained for several of
the more conventional "mechanical" two- and three-stage filter systems currently qualifying by
Method 319. Accordingly, the commenter recommended that the Agency make an allowance for
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these hybrid "mechano-electrostatic" filters (and, for that matter, any future filter system yet to be
developed) to be tested by Method 319 procedures, and to be certified as such if they pass.
To satisfy the concerns of those who would want to be certain that any prospective hybrid
filter system must never decrease in fractional efficiency over time, the commenter recommended
that the complete test of a prospective filter system, such as one of these hybrid mechano-
electrostatic filters, should not only include the full Method 319 analysis but also a standard dust-
loading-efficiency test, or an additional fractional efficiency test using actual paint. Adding one of
these additional tests would demonstrate whether the filter in question continues to increase in
efficiency over time or not One approach would be that the additional test could be done once
on a mechano-electrostatic filter (set) and once on an identical uncharged mechanical filter (which
should be readily provided by the manufacturer), both of which had been tested by Method 319.
If dust loading is used, then a loading-efficiency test similar to the ASHRAE 52 2 procedure used
for HVAC filters would show whether efficiency decreases by loading to mimic the paint loading
condition If the test for fractional efficiency with actual paint is used, this would provide
comparative data of both mechano-electrostatic and mechanical conditions and authenticate
whether these filters are good for use as paint overspray filters
The commenter noted that, if the proposed amendment were finalized, Method 319 would
exclude electrostatic filters from testing However, when the method was first written, the
working definition of electrostatic media did not take into consideration or anticipate these newer
hybrid media because they were not yet available at that time The commenter believed that new
inventions that fully meet Method 319 testing requirements and improve upon conventional
filtration technologies would be automatically excluded from testing and certification under
Method 319 Assuming the goal of Method 319 testing is not only to approve certain filters
under certain conditions but also to reduce the amount of hazardous particles impacting the
environment and workers' health, the EPA should allow and even encourage the testing and
utilization of best available technologies to accomplish these goals At a minimum, a mechanism
within Method 319, such as the dust-loading or paint fractional efficiency test described above,
should be available for new alternative technologies to be tested and given certification if they
truly accomplish what Method 319 requires them to do
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Response The Agency has decided that the proposed amendment to exclude
electrostatically-charged filter media from Method 319 testing (based on the possibility that their
efficiency in use will drop below that measured in Method 319 testing) will not be finalized based
on the fact that there are insufficient data at this time to warrant this exclusion. No data were
submitted illustrating that electrostatically charged filter media will actually drop in efficiency
during use in aerospace painting and depainting facilities. Furthermore, no data were submitted
showing that, even if such drops in efficiency do occur, similar drops would not also occur in
uncharged media (i.e., the drop in efficiency may not be solely due to a loss of electrostatic
enhancement but may also be due to other physical changes in the media, which occur over time).
The Agency recognizes that this is an area of current, active, and ongoing research The Agency
is also aware of studies conducted on electrostatically charged filters used in general ventilation
that do, for some charged-fiber filters under certain operating/exposure conditions, show drops in
efficiency for electrostatically-charged media However, the relevance of these findings to
arresters used in aerospace painting and depainting facilities is uncertain and is, therefore,
insufficient to exclude, as a category of arresters, electrostatically charged media from
Method 319 testing
Two commenters suggested expanding Method 319 to include not only the initial
efficiency, but also one or more steps of paint loading followed by a repeated filtration efficiency
measurement after each step, by doing so, changes in electrostatically charged filtration
efficiencies, if present, would be measured One of the commenters recommended that
Method 319 be expanded to include standard dust loading efficiency tests, or an additional
fractional efficiency test using actual paint. These type of tests would need to account for the
replacement frequency of the various stages in a multistage system, and load the filter with
representative paint oversprays, as well as depainting-generated aerosols and ambient aerosols
which may be drawn into a spray booth, perhaps with some level of prefiltration There are no
standardized methods that adequately address these issues relative to conditioning or aerosol-
loading of multistaged arrestors for the purposes of quantifying potential changes in fractional
efficiency with use. In light of the Aerospace NESHAP compliance date of September 1, 1998, it
is beyond the scope of this project at this time to continue modifications to Method 319. Thus,
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use of Method 319, as stated in the final amendments to the aerospace rule published in the
Federal Register on March 27, 1998, is retained.
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1 REPORT NO
F.PA-453/R-98-009d
TECHNICAL REPORT DATA
(Please read Instructions on reverse before completing)
2
4 TITLE AND SUBTITLE
Aerospace Manufacturing and Rework Industry-
Background Information and Promulgated Standards
ADDENDUM
7 AUTHOR(S)
9 PERFORMING ORGANIZATION NAME AND ADDRESS
Emission Standards Division (Mail Drop 13)
U. S. Environmental Protection Agency
Research Triangle Park, NC 27711
12 SPONSORING AGENCY NAME AND ADDRESS
Office of Air Quality Planning and Standards
U.S. Environmental Protection Agency
Research Triangle Park. NC 27711
3 RECIPIENT'S ACCESSION NO.
5. REPORT DATE
July 1998
6 PERFORMING ORGANIZATION CODE
8 PERFORMING ORGANIZATION REPORT NO
10. PROGRAM ELEMENT NO
Task Order No. 0012
1 1 CONTRACT/GRANT NO
68-D6-0012
13 TYPE OF REPORT AND PERIOD COVERED
Final
14 SPONSORING AGENCY CODE
EPA/200/04
15 SUPPLEMENTARY NOTES
EPA Task Order Project Officer: Barbara Driscoll. ESD/PPSG
16 ABSTRACT
National emission standards for control of HAP emissions from aerospace manufacturing and rework
facilities were published in 60 FR 45948, September 1, 1995. Proposed amendments to the final rule were
published in 63 FR 15034, March 27, 1998. This addendum to the background information document
provides: the basis for the revisions (amendments) made to the standards since promulgation; a summary
of the comments submitted and the responses to these comments; and a summary of the changes made
since promulgation.
17
a DESCRIPTORS
KEY WORDS AND DOCUMENT ANALYSIS
b IDENTIFIERS/OPEN ENDED TERMS c COSATI Field'Grour
Air Pollution Cleaning Operations Air Pollution Control
Aerospace Manufacturing Surface Coating MACT
and Rework (Painting) Coating Operations
Hazardous Air Pollutants Depainting Cleaning Operations
18 DISTRIBUTION STATEMENT
Release Unlimited
19 SECURITY CLASS (Kepun) 21 NO OF PACES
Unclassified 24
20 SECl'RITY CLASS /Page) 22 PRICE
Unclassified
EPA Form 2220-1 (Rev. 4-77)
PREVIOUS ED1TIOS IS OBSOLETE
4SOOQyfiiul/trd
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U.S. Environmental Protection Agency
Region 5, Library (PL-12J)
77 West Jackson Boulevard, 12th Float
Chicago, !L 60604-3590
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