United States Office of Air Quality EPA-450/3-82-025
Environmental Protection Planning and Standards October 1982
Agency Research Triangle Park NC 27711
Air ~
Performance
Specification 1 -
Specifications
and Test Procedures
for Opacity
Continuous Emissions
Monitoring Systems
in Stationary Sources -
Summary of Comments
and Responses
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EPA-450/3-82-025
Performance Specification 1 - Specifications
and Test Procedures for Opacity Continuous
Emissions Monitoring Systems in Stationary
Sources - Summary of Comments and Responses
Emission Measurement Branch
Emission Standards and Engineering Division
U.S. ENVIRONMENTAL PROTECTION AGENCY
Office of Air, Nosie, and Radiation
Office of Air Qualty Planning and Standards
Research Triangle Park, North Carolina 27711
October 1982
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This report has been reviewed by the Emission Standards and Engineering Division of the Office of Air
Quality Planning and Standards, EPA, and approved for publication. Mention of trade names or
commercial products is not intended to constitute endorsement or recommendation for use. Copies of
this report are available through the Library Services Office (MD-35), U.S. Environmental Protection
Agency, Research Triangle Park, N.C. 27711, or from National Technical Information Services, 5285
Port Royal Road, Springfield, Virginia 22161.
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TABLE OF CONTENTS
Page
Chapter 1. INTRODUCTION '
Chapter 2. SUMMARY OF CHANGES SINCE PROPOSAL 1
Chapter 3. SUMMARY OF COMMENTS AND RESPONSES 9
TABLE 2-1. LIST OF COMMENTERS ON
PROPOSED PERFORMANCE
SPECIFICATION 30
m
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CHAPTER 1
Introduction
Performance Specification 1 - Specifications and Test Procedures
for Opacity Continuous Emission Monitoring Systems in Stationary
Sources - was first promulgated in the Federal Register (40 FR 64250)
on October 6, 1975. Revisions to this specification were proposed
on October 10, 1979, in the Federal Register (44 FR 58602). Prior
to the proposal of the revisions, copies of the proposal were
distributed for comment to the Environmental Protection Agency (EPA)
regional offices, State and local air pollution control agencies,
manufacturers of continuous emission monitoring equipment, and concerned
industries. Comments from these sources were considered, and amendments
were made before the proposal.
A public comment period from October 10, 1979, to December 10,
1979, was originally set following the proposal. The deadline for
public comments was extended to February 11, 1980. In all, 23 comment
letters were received. The comments received along with EPA's responses
are summarized in this document. The summary of comments and responses
serves as a basis for most of the revisions that have been made to the
test methods between proposal and promulgation. Some changes to the
proposed Performance Specification (PS) 1 are based on information obtained
by EPA from additional experience with the procedures.
CHAPTER 2
Summary of Changes Since Proposal
Several significant changes to Section 60.13 have been included
since proposal of the revisions to PS 1. One of the more important
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of these concerns the applicability of the new PS 1. Section 60.13
of 40 CFR Part 60 has been revised to specify that PS 1 applies
to all new monitors installed on or after the promulgation date and
further specifies which sections do not apply to existing monitors.
If an existing monitor is modified or moved, the revision notes how
the new PS shoald be applied.
Other changes to Section 60.13 clarify the reporting requirements
for multiple monitors and for the number of values used in the
average.
Several changes have been made to PS 1 since proposal. Most of
the changes were made to clarify procedural and design specification
issues raised by commenters following proposal. One significant
change involves the location requirements. More flexibility
in the location of transmissometers in horizontal ducts is permitted.
Figures have been added to the method to clarify the specifications as
to location of transmissometers in most conceivable situations.
Procedures for determining alternative locations were clarified,
and the limit for acceptance was modified to allow for this
determination under conditions of very low opacity.
Some of the design specifications that had been made more restrictive
in the proposed revisions were returned to the original values.
For example, the spectral response of between 515 and 586 nm
in the proposal was returned to the 500- to 600-nrn range found in the
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original PS 1. The Agency reviewed this proposed change and the ones
for angles of view and projection, and determined that little increase
in data accuracy or reliability was gained with the more restrictive
limits. In addition, some presently available transmissometers would fail to
meet some or all of the more restrictive limits.
An external calibration filter access has been added to
PS 1 as an option. The Agency is developing quality assurance procedures
for continuous monitors that will contain periodic audits for accuracy
with external filters. A transmissometer equipped with access for
external calibration filters will greatly facilitate this type of
assessment.
Specific changes to PS 1 made since proposal are listed by section
number below:
1. Section 2.7. Mean Spectral Response. The definition of
the mean spectral response was changed to be consistent
with the calculating procedure.
2. Section 2.18.2. Emission Outlet Path Length. The procedure
for calculating the equivalent outlet path length for noncircular
stacks was added to this section.
3. Section 3.2. Calibration Attenuators. This section was
revised to specify attenuators of sufficient size to attenuate the
entire received beam, instead of the entire projected beam.
4. Section 3.3. Upscale Calibration Value Attenuator. The
required range for the filter was changed to a value greater than
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or equal to the applicable opacity standard, but less than or equal
to one-half the instrument span Vclue.
5. Section 3.4. Calibration Spectrophotometer. The accuracy
of the spectrophotometer specified as <0.5 percent transmittance
has been-retained, but the provision that the instrument calibration
be National Bureau of Standards traceable was added.
6. Section 4. Installation Specifications. This section was
edited to delete the specific requirement that "A measurement path
that represents the average opacity over the cross section" is used.
The specifications still require an installation where the opacity
measurements are "representative" of the total emissions.
7. Section 4.2. Measurement. Path. This section was changed
to require a measurement path passing through the centroidal area
comprising 25 percent of the total cross-sectional area of the
duct. Figures 1-1 to 1-5 were added to clarify measurement path
requirements.
8. Section 4.2.1. Locating Requirements. This section was
divided into two separate sections.
9. Section 4.2.4. Horizontal ducts. This section was changed
to require the monitor to be located in a position between one-third
and one-half the distance up the vertical axis. Previously, the monitor
was required to be mounted one-third the distance up the vertical axis.
10. Section 4.2.5. Horizontal Ducts (multiple bends). Same
as Section 1.3, above.
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11. Section 4.3. Alternate Locations and Measurement Paths.
Previously, this section stated that the average opacity at an
alternative location should be within +_10 percent of the average
opacity value measured at an acceptable location. This criterion
has been modified to +_10 percent or 2 percent opacity, whichever is
greater. This section now specifically states that alternative
procedures for determining acceptable measurement locations may be
used, if approved by the Administrator.
12. Section 5. Design Specifications. Section 5 (Design
Specifications) and Section 7 (Performance Specifications) have been
combined into a single section.
13. Section 5.1.1. Spectral Response. The design specification
for the mean and peak spectral responses has been changed to between
500 and 600 nm (from between 515 and 585 nm).
14. Section 5.1.2. Angle of View. The design specification
for the angle of view has been changed from 4 to 5 degrees.
15. Section 5.1.3. Angle of Projection. The design
specification for the angle of projection has been changed from
4 to 5 degrees.
16. Section 5.1.4. Optical Alignment Sight. The requirement
for an optical alignment sight for "zero pipe" systems was deleted,
where these systems are capable of an absolute across stack zero
while maintaining the same optical alignment during the measurement
and calibration.
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17. Section 5.1.7. Automatic Zero Compensation Indicator.
The requirement for an indicator to show that a condensation of
4 +_ 0.5 percent opacity is exceeded was revised to require an
indicator to show when 4 percent opacity has been exceeded.
18. Section 5.1.9. External Calibration Filter Access
(optional). An additional design specification has been recommended
to permit external checks in order to assess the precision and accuracy
of the monitoring data.
19. Table 1-1. Performance Specifications. The specification
for the recorder resolution was changed to less than or equal to
0.5 percent opacity.
20. Section 6. Design Specifications Verification Procedures.
The calculation instructions (Section 9) were combined with the
appropriate paragraphs in Section 6.
21. Section 6.2. Angle of View. In order to be consistent
with the change in design specification (4 to 5 degrees), the
performance specification procedures have been slightly changed; the
specified 4 and 24 centimeters jsed during the procedures have been
changed to 5 and 30 centimeters, respectively.
22. Section 6.3. Angle of Projection. Same changes as 1.19,
above.
23. Section 7. Performance Specification Verification
Procedure. This section has been clarified to specify that the
verification tests are conducted with the data recording system to
be used during monitoring.
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24. Section 7.1.1. Equipment Preparation. A requirement
has been added for actually measuring the monitor path length to be
used in the installation (the distance calculated from drawings
is not sufficient). Additional criteria for aligning the instrument
during the preliminary adjustments are added; i.e., the instrument
is to be aligned so that maximum instrument response is obtained
prior to zero alignment.
25. Table 1-2. Required Calibration Attenuator Values. This
table has been expanded to include span values of 40 percent opacity.
26. Section 7.1.3. Attenuator Calibration. The requirement
for checking 75 percent of the attenuator area was deleted; checking
several different portions of the attenuator is required.
27. Section 7.1.4. Calibration Error Test. This section was
revised to require that only the entire beam received by the detector
must pass through the calibration attenuator (instead of the entire
projected beam). Additionally, the specification that the attenuators
be placed in the measurement beam was clarified. Measurements taken in
the instrument housing are not permitted unless the manufacturer
receives prior approval from the Administrator.
28. Section 7.2.1. Optical and Zero Alignment. A recommendation
was added suggesting that a "clear stack" condition be verified prior
to conducting the zero alignment.
29. Section 7.4. Operational Test Period. This section was
reworded to clarify that all adjustments, realignments, and lens
cleanings during the operational test period must be logged.
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30. Section 7.4.1. Zero Drift Test. The calculating
procedures from Section 9 were combined with this section.
31. Section 7.4.2. Upscale Drift Test. The calculating
procedures from Section 9 v/ere combined with this section.
32. Table 1-3, t Values. The t value for n=8 has been
corrected (correct value is 2.36i5).
33. Section 8.4, Equation 15. Equation 15 has been corrected.
The correct equation is D~ = D, (Lp/U).
34. Section 9.1(f). General Information. This section,
requiring the date of monitor manufacture to be reported, has been
added.
35. Section 9.2(h). Design Specification Test Results.
This section has been added, requiring reporting of the serial
number and date of manufacture of the monitor tested to show compliance
with the design specifications when a manufacturer's certificate of
conformance was provided.
36. Section 10. Retest. This section was rewritten to
clarify what portion(s) of the performance test must be repeated when
the instrument fails the test.
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CHAPTER 3
Summary of Comments and Responses •
The list of commenting organizations is shown in Table 2-1
of this chapter. Twenty-three letters contained comments on proposed
Performance Specification 1. The comments and issues and the
responses to them are discussed in this chapter.
Commenters IV-D-1, et al.
1.1 Comment: The requirement of 0.5 percent full-scale
resolutions for the recording system is ambiguous, since no criteria
were given for measuring this value, and it is overly restrictive.
Is the correct value 5.0 as stated in the preamble or 0.5 as stated
in the regulation?
Response: The requirement has been clarified to specify a
resolution of 0.5 percent opacity. This means that for an application
using a strip chart recorder with a 100 percent opacity span value on
the instrument, the recorder would be required to have 100 division
so that the operator could extrapolate to 0.5 division (0.5 percent
opacity).
Commenter IV-D-3
3.1 Comment: Equation 1-5 is incorrect and should be written
as D2 = D1 (Lg/l^).
Response: This equation was corrected.
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3.2 Comment: Sections 4.2.1 and 4.2.2 (monitor locations)
are redundant.
Response: Although these sections are similar, Section 4.2.1
gives the appropriate monitor location when a single bend is involved,
whereas Section 4.2.2 gives the appropriate location for a monitor
between two bends.
3.3 Comment: The transmissometer used for comparison testing
to determine alternate locations must be specified to meet the
requirements of the specification. Would a portable monitor which
does not measure the full stack diameter be acceptable for comparison
testing?
Response: The transmissometers should meet the design criteria
of this specification and should be properly calibrated. The
requirement for 24-hour calibration systems is unnecessary. With the
portable unit, one must consider the application,. Use of a transmissometer,
which does not measure the entire diameter of a circular duct, is
inappropriate for determining whether stratification exists across a
particular location of that duct. On the other hand, if the portable
transmissometer is used in a horizontal duct where stratification is
expected only along the vertical axis, it may not be necessary to measure
completely across the duct to determine whether stratification exists.
Good engineering judgment should be used when determining the test criteria.
10.
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Commenter IV-D-5, et al.
5.1 Comment: As stated in the summary of the proposed
regulation, PS 1 would apply to instruments already installed. This
would mean relocating and changing monitors because of the location
specifications and additional requirements (e.g., alignment sight,
upscale calibration values). This will result in significant expendi-
tures with no improvement in accuracy, reliability, or
enforcement capability of those instruments.
Response: The Agency (EPA) agrees with this comment. Paragraph
60.13 of 40 CFR 60 has been changed stating that transmissometers prior
to the promulgation date of this revised PS 1 will be exempted from certain
specifications. Upon replacement of an existing monitor with a new system,
the revised PS will apply except the new monitor may be located at the
old measurement location, regardless of whether that location meets the
new requirements. If a new location is determined in such a case, the
new location must also meet the new specifications.
5.2 Comment: There is no justification for requiring monitoring
in the lower or upper portions of horizontal ducts. Locating the
monitor at the midpoint should be permitted. This will allow
measurement of opacity and gaseous pollutant concentrations from
the same location.
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Response: EPA changed the specification for horizontal ducts to
locate the monitor somewhere between the midpoint and upper (or lower)
third of the duct. This change will provide greater flexibility.
5.3 Comment: The proposed criteria for demonstrating acceptable
alternate locations are not stringent enough and additional information
(e.g., effect of temporal and process changes) must be taken into
consideration.
Response: The overall purpose of the monitor location
specifications is to provide some basic requirement to simplify the
task of locating the monitor. In like manner, the procedure for
determining alternative locations is to provide guidelines for determining
that a gross stratification problem does not exist in an alternative
location requested by the source or by the Agency. As such, EPA
feels this procedure is adequate for determining whether an alternative
location is acceptable.
5.4 Comment: The requirement for an alignment sight should be
deleted on zero pipe units since an absolute zero is checked.
Response: The Agency agrees that an alignment sight for some
zero pipe models would not be necessary when the instrument is
capable of providing an absolute zero check with effluent present
while maintaining the same optical alignment during measurement and
calibration. Section 5.1.4 has been revised to reflect this change.
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5.5 Comment: The 90 percent requirement for slotted tubes
is restrictive; 66 percent is sufficient. The 90 percent requirement
is ambiguous, since the technical definition of "monitor path length"
indicates that the slotted length for a purged slotted tube system
would always be 100 percent of the depth of the effluent.
Response: The Agency does not have sufficient data comparing
measurements over short and total path lengths. The responsibility
lies with the facility to show that a shortened path length is
adequate. The intent of the provision is to require 90 percent of
the effluent stream (as measured between duct walls) to be monitored.
Section 5.1.8 has been reworded to properly reflect this intent.
Commenter IV-D-6, et al.
6.1 Comment: Which of the two different angles of
view/projection - 3 or 4 degrees - is correct? An angle of 3 degrees
would cause a large portion of the existing monitors not to meet this
specification and would cause alignment problems.
Response: A 4-degree value was intended for proposal. After
reconsideration, the advantage gained by tightening this specification
from 5 to 4 degrees was deemed to be small; therefore, the Agency
has decided to retain the present 5-degree values for the angle of
view and angle of projection.
6.2 Comment: The amount of automatic zero compensation should
not be included in the calculation of zero drift. This is no more
1 "5
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valid than requiring the reporting of automatic compensation for
other drift factors such as temperatures and voltages.
Response: The amount of automatic zero compensation (for dirt
accumulation) must be taken into account during the zero drift
calculation. Measurement of zero drift after compensation would be
inappropriate since the drift would always appear to be zero. The.basic
operating principle of the automatic zero compensation is simply to
reset the instrument response to zero if a nonzero value is obtained
during zero calibration. For dual pass instruments this compensation
is based on "dirt accumulation" on the transmitter/receiver unit and
assumes the dirt accumulation on the reflector unit to be equal;
therefore, this correction may lot be accurate. On the other hand,
other automatic compensations (line voltage drifts, etc.) are normally
handled by balancing electronic signals in the operating unit. If
incorrect compensation is made, this would show up as zero drift
during the zero calibration check (in the same manner as if no correction
were made for drift).
6.3 Comment: Provisions should be made to accept measured
instead of calculated spectral response data to determine compliance
with the spectral response design specification.
Response: Section 1.1 of PS 1 allows alternative procedures.
There should be no problem with receiving permission to use this approach.
Nonetheless, Section 6.1 has been revised to state explicitly that
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the monitor spectral response characteristics may be determined
by laboratory measurement.
6.4 Comment: The requirement for an alignment sight needs to
be clarified. The requirement is inadequate and must include testing
both lateral and rotational misalignment for both the transceiver
and reflector units.
Response: The specification has been clarified. Since no units
currently provide means for checking rotational misalignment on the
reflector end, EPA feels that it is not practical to require an
indicator to be provided for this type of misalignment. If the unit
is properly calibrated and installed, any bias due to rotational
misalignment would be positive. Therefore, proper procedures during
calibration and installation will be required in order to reduce the
effects of rotational misalignment. Section 7.1.1 requires that
during the preliminary equipment setup the rotational alignment is
adjusted to produce the maximum instrument output.
6.5 Comment: The calibration error test should permit placing
the calibration attenuators inside the instrument housing.
Response: The Agency feels the attenuators should be placed
in the actual effluent measurement path in order to assure accurate
results. Alternative procedures are acceptable upon approval of
the Administrator.
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6.6 Comment: Including the calibration error test and response
test as part of the operational test period implies these tests
should be conducted during the 168-hour test period. It is better
to conduct these tests off the stack at the manufacturer's facility.
Response: The calibration error and response tests are not
included as part of the operational test period, but as part of the
preliminary adjustments and tests. The introduction to this section
specifically states that these tests may be conducted at the
manufacturer's facility.
6.7 Comment: Sections 9.10.3(g) on lens cleaning clock time
and 9.10.3(h) on optical alignment adjustment clock time are not
clear.
Response: These sections simply mean that if any lens cleaning
or alignments are made during the performance test, the time the
action was taken is to be reported.
6.3 Comment: The "retest" requirements are unclear and could
be misinterpreted as to what tests must actually be repeated if the
monitor fails the 168-hour operational test period.
Response: This section was reworded to indicate that, in
general, only the 168-hour operational test period should be repeated
(after corrective measures have been taken) if the monitor fails the
initial operational test period. However, if significant changes are
made to the monitoring system (e.g., light source, photodetector, major
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electronic components), it may be necessary to repeat the preliminary
performance tests. Judgment must be used in determining which tests
are to be repeated.
Commenter VI-D-9
9.1 Comment: Section 7.2.2 (optical and zero alignment--
alternative procedure) should refer to the optical alignment sight
for verifying proper alignment.
Response: This section has been reworded to clarify the
importance of proper alignment. Reference has been made to use of
the optical alignment sight.
9.2 Comment: The optical alignment of the instrument should
be performed during the initial equipment preparation (Section 7.1.1)
and prior to the initial zero alignment.
Response: This comment is correct. This instruction has been added
to the procedure.
9.3 Comment: The recorder system to be used during monitoring
•is often not used with the monitor during the performance test.
Procedures should be established for handling this situation when
it occurs, or this situation should be specifically prohibited.
Response: The definition of the continuous emission monitoring
system (CEMS) (Section 2.1) implies that the data recorder is
to be included in the performance testing. This is
certainly the intent of the specification; however, the Agency
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feels it is impractical to prohibit specifically the use of a
substitute data recorder. Section 7 has been revised to state explicitly
that prior approval of the Administrator is required if
different data systems are used during the performance test and
monitoring.
9.4 Comment: The manufacture date of the affected monitor
should be reported; in addition, if a manufacturer's certificate
of conformance is used to show compliance with design specifications,
the serial number and date of manufacture of the monitor actually
tested should be reported.
Response: The suggested information has been added to the
reporting requirements (Section 9).
9.5 Comment: The correct monitor path length is critical to
the proper zero alignment of the instrument when the final zero
alignment is conducted off-stack (alternative procedure).
Consequently, the monitor path length should be measured, rather than
estimated from plant drawings.
Response: The Agency agrees. A requirement: that the monitor
path length be measured prior to conducting an off-stack zero
alignment has been added to Section 7.1.1.
Commenter VI-D-14
14.1 Comment: The allowable misalignment should be specified
in Table 1.1 as a performance specification.
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Response: The criterion for an alignment sight is a design
specification. The intent is to provide a quality control check
for the facilities to determine if and when alignment might be a
problem at a specific source. Note that any misalignment will cause
a positive bias. The Agency does not feel it is necessary to require
an alignment specification for the 168-hour operational test period.
14.2 Comment: Table 1-2 lists the calibration filters to be
used for span values of 50 percent or greater. Since, at least one
regulation has been proposed with a 40 percent span value, the table
should be expanded.
Response: The table has been expanded.
14.3 Comment: An additional performance specification should be
added to assess the relative accuracy of the CEMS as compared to EPA
Method 9. This is appropriate since the CEMS is designed to substitute-
for the visible emission observer.
Response: This comment is not appropriate because the opacity CEMS is
intended as a tool for continuously assessing the effectiveness of
operation and maintenance practices of the control system and
not as a substitute for visual observations, which are used to determine
compliance with opacity standards.
14.4 Comment: Equations 1-2 and 1-3 are incorrectly labeled
as 2-1 and 2-2.
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Response: The equations' identifications have been corrected.
Commenter IV-D-17
17.1 Comment: How is the outlet path length calculated for
noncircular stacks?
Response: The calculation is for the hydraulic diameter,
i.e.,
_ 2LW
This equation has been added to Section 2.18.2.
17.2 Comment: Specifications must be written for determining
whether an instrument responds to ambient light.
Response: The Agency feels that sound judgment based on an
analysis of the instrument design, location, and operation is
sufficient to determine if an instrument output is affected by
ambient light.
17.3 Comment: The criterion of +_10 percent for determining
acceptable alternative locations is too restrictive for low level
opacities. A minimum acceptable difference of 1 percent opacity
is suggested.
Response: The Agency agrees. The specification has been
rewritten with a criteria of +10 percent or 2 percent opacity,
whichever is greater.
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17.4 Comment: The angle of view/projection procedure does
not provide adequate measurement precision.
Response: The Agency feels the procedure is adequate, but
alternative procedures may be approved, if requested.
17.5 Comment: No specifications are provided for the photode-
tector used in the angle of projection test (e.g., detector
linearity). Since photodetectors can be extremely nonlinear,
the angle of projection test can have erroneous results.
Response: Again, the Agency feels details of this sort should
be left up to the manufacturer. Note that photovoltaic cells are
generally linear in the range of low-level illumination, but become
nonlinear as the illumination level increases (cell saturation).
Consequently, use of a cell in the nonlinear range would be to the
manufacturer's disadvantage since the output at wider angles would
appear as a greater percentage of the maximum output, resulting in
an apparent larger angle of view.
17.6 Comment: Alternative angle of view test procedures should
be written for instruments using modulated light sources since the
photodetector will not respond to a nonmodulated light source.
Response: The Agency position is that design test procedures
are best handled by the manufacturer of the instrument. The purpose
of the procedure in PS 1 is to provide basic guidelines.
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17.7 Comment: The optical alignment specification test
should allow the option of performing the design test at the
installed path length, rather than at 8 meters; 8 meters is
excessively restrictive for short path lengths.
Response: The specification is intended as an instrument
design specification, not as a performance specification; therefore,
a standard criterion for all instruments is inappropriate. In fact,
this approach should simplify matters for the affected facilities
since the instrument vendor can conduct this test at its
laboratory and can certify that the design criterion is met.
17.8 Comment: Is the upscale calibration attenuator subject
to the attenuator calibration procedures (Section 8.1.3, proposed
regulation)? The upscale calibration attenuator does not provide
the fundamental calibration of the instrument and, therefore, should
not need to meet the stringent ca'ibration procedure; it serves as
a stability check providing a means of checking instrument response
once the unit is in operation. The 3-month recertification
requirement of the calibration procedures should specifically not
apply to the upscale attenuator, since this would require the
attenuator be removed from the monitoring unit at 3-month intervals.
Response: The Agency agrees. The fundamental calibration (and
linearity) of the instrument is determined by the calibration
attenuators (low, medium, and high range). The upscale calibration
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value is provided as a means of assuring the instrument response
(calibration) remains constant over an extended time period.
Consequently, once the instrument has been properly calibrated,
the upscale calibration value can -be measured by the calibrated
monitoring system and recorded. This value then becomes the
reference by which the calibration drift is measured. Note, however,
that this procedure requires the upscale calibration value to be
established on an instrument that is properly calibrated with the
certified attenuators. Furthermore, the specification requires that
these calibrations be conducted on a path-corrected basis and with the
actual monitoring system data recorder.
17.9 Comment: The definition of the mean spectral response
does not support the normal procedures used for calculating this
value; i.e., the calculation normally used actually determines the
first moment of the spectral response distribution, not the wavelength
which bisects the total area under the effective spectral response
curve.
Response: The definition of the mean spectral response has
been changed to be consistent with the calculations normally used
(i.e., calculation of the arithmetic mean value).
Commenter IV-D-19
19.1 Comment: The indicator for the amount of automatic zero
compensation (dirt accumulation) should not be required since the
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initial operational test period adequately defines the required
cleaning frequency.
Response: The Agency position is that if automatic compensation for
dirt accumulation is permitted, it is reasonable to require some
form of indicator to assure that the compensation does not become
excessive.
Commenter IV-D-20
20.1 Comment: The upscale calibration attenuator value should
be specified at the level of the standard instead of a level higher
than the standard. This better quantifies the accuracy near the
value of the standard.
Response: The criteria have been changed to require an upscale
calibration value equal to or greater than the opacity standard,
but less than or equal to one-half the instrument span value. Stipulating
a calibration value at the level of the standard might pose a problem
in cases of a low standard, i.e., accurate attenuators may not be
available. The range permitted by the specification will provide
a reasonable amount of flexibility in choosing the calibration value.
20.2 Comment: An additional performance specification should be
added to assess the accuracy of the transmlssometer relative to EPA
Method 9 as the transmissometer is designed to substitute for the visible
emission observer.
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Response: See response 14.3.
20.3 Comment: The t value for N=8 in Table 1-3 should
be 2.365, not 2.385.
Response: The value has been corrected.
Commenter IV-D-22
22.1 Comment: Requiring the monitor to be placed downstream
of all particulate control systems except where condensed water
vapor is not present may preclude installation after scrubbers
where supersaturated conditions exist. Furthermore, 40 CFR 60.47a(a)
(Subpart Da) requires the monitor to be installed upstream of the
flue gas desulfurization (FGD). Yet, in this case the opacity monitor
would provide no value in determining compliance with the particulate
opacity standard of Section 60.42a(b).
Response: It is true that monitors may be precluded from use
after scrubbers when condensed water vapor is present. Regarding the
provisions of subpart Da, the monitor is not intended to be used
for determining compliance with the particulate opacity standard;
EPA Method 9 is the reference test method. The purpose of the monitor
placed before the FGD but after the primary particulate control system
is to determine the effectiveness of control system operation and
maintenance practices.
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22.2 Comment: The calibration procedure for the attenuators
is not adequate; the calibration must be traceable to NBS standards.
Response: The specified accuracy of the calibration
spectrophotometer of +2 percent opacity implies some standard is
used for instrument calibration. The specification has been changed
to require spectrophotometer calibration that is NBS traceable.
Commenter IV-D-27
27.1 Comment: The optical sight indicator is riot required on
transmissometers that use a zero-pipe in determining zero and
calibration conditions.
Response: See Response 5.4.,
27.2 Comment: The requirement for a 90 percent: or greater optical
path for systems with slotted tubes should be reduced to 67 percent.
Response: See Response 5.5.
Commenter IV-D-29
29.1 Comment: The 3-month recalibration requirement for
calibration attenuators is excessive and not necessary. The
requirement for checking 75 percent of the filter surface area is
excessive.
Response: The Agency does riot feel 3 months is excessive;
the need for recalibration probably depends heavily on the type of
26
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attenuator, frequency of use, and care in handling. If data are
available to show less frequent calibrations are required, a change
in procedure could be requested from the Administrator. The criterion
for measuring 75 percent of the surface area has been deleted from the
specification, and the requirement for checking several quadrants has
been added.
Commenter IV-D-31
31.1 Comment: Why was the zero offset deleted?
Response: The zero offset was deleted because some monitoring
CEMS cannot be offset because of the electronics of the system. The
Agency felt the offset was not required because any negative zero
drift that does not show up when an offset is not being used will
appear as a negative span drift.
31.2 Comment: There should be some criteria for determining
whether a clear stack condition exists prior to conducting an in-situ
zero alignment, e.g., using an instantaneous mode of data output and
noting whether fluctuations occur in the measured values.
Response: The Agency does not feel it is necessary to require
specific criteria for a clear stack determination; however, a
suggestion that careful thought be given to assuring that a zero stack
condition exists has been added to this section.
31.3 Comment: Why was the requirement for a 1-year zero
realignment deleted?
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Response: The 1-year zero realignment is actually a quality
assurance procedure and not a system performance specification. For
this reason, the requirement was deleted from the specification. The
requirement for a routine check of zero alignment will be considered
for inclusion in quality assurance guidelines for monitors.
Commenter IV-D-33
33.1 Comment: Opacity monitors (transmissometers;) may not be
the best instrument for certain monitoring application (e.g., baghouses).
PS 1 should include provisions for allowing other types of monitors
such as light backscattering, laser, and beta-ray absorption instruments.
Response: The purpose of PS 1 is to provide performance and
design specifications for transmissometers. It is true that transmissometers
may not provide the best monitoring data for certain types of facilities.
The EPA Office of Research and Development is currently evaluating
different types of instrumentation. Once these monitors have been
evaluated and it is determined that they provide adequate monitoring
data, specifications for the new irstrumentation will be written.
It should be noted that Section 60.13(g)(8) of the regulation
40 CFR 60 states that alternative monitoring systems (not meeting
PS 1) may be used if the system is "adequately demonstrated to show
a definite and consistent relationship between its measurements and
the measurement of opacity by a system complying with Performance
Specification 1."
?q
_o
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TABLE 2-1. LIST OF COMMENTERS ON PROPOSED
PERFORMANCE SPECIFICATION 1
DOCKET OAQPS 79-4
(Continued)
Document Number
IV D-20
22
24
25
27
28
29
31
33
34
Commenter
John D. Janak
Texas Utilities Services
Herbert Wortreich
State of New Jersey
Department of Environmental
Protection
William 0. Parker, Jr.
Duke Power Company
James H. Rathlesberger
U.S. Department of Interior
Alan E. Opel
Environmental Data Corporation
Neil S. Grigg
North Carolina Department of
Natural Resources and Community
Development
Mohamed T. El-Ashry
Tennessee Valley Authority
John W. Prohaska
South Carolina Department of
Health and Environmental Control
Ralph D. Grotelveschen
Deere and Company
Richard J. Wyers
Contraves-Goerz Corporation
31
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TECHViCAL «E?C" O
EPA-450/3-32-025
T _ c A M Q 5 ._, 3 7 . 7 L E
Performance Specification I - Specifications and Test
Procedures for Opacity Continuous Emission Monitoring
Systems in Stationary Sources - Summary of Comments
October 1982
Emission Standards and Engineering Division
JE~ = ~i=MI- ~ ORGANIZAT CM NAME ANO ADDRESS
Emission Measurements Branch.(MD-19)
Emission Standards ana Engineering Division
U.S. Environmental Protection Agency
Research Triangle Park, NC 27711
'2 SPOMSCB'.VG AG£MCV NAME A/VJO ADDRESS
OAA for Air Quality Planning and Standards (MO-10;
Office of Air, Noise, and Radiation
j.S. Environmental Protection Agency
Research Triangle Park, NC 27711
IT TYP£ O<= REPORT AiND PERIOD CC'-'SnSD
1^ SPONSORING AGENCY COCE
EPA 200/04
NCTES
This document addresses the public comments submitted after proposal
of Performance Specification 1 in the Federal Register. Changes made as
the result of these comments are included.This document serves as the basis
for the revisions made in Specification 1 between proposal and promulgation.
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