217. In Part 60, Appendix B is amended by revising

Performance Specifications 2, 3, 4, 4A, 5, 6, 7, 8, and 9 to read as follows: 1535

PERFORMANCE SPECIFICATION 2 - SPECIFICATIONS AND TEST PROCEDURES FOR SO 2AND NOXCONTINUOUS EMISSION MONITORING

SYSTEMS IN STATIONARY SOURCES 1.0 Scope and Application. 1.1 Analytes.

Analyte CAS Nos. Sulfur Dioxide (SO 2 ) 7449-09-5 Nitrogen Oxides (NO x ) 10102-44-0 (NO 2 ),

10024-97-2 (NO) 1.2 Applicability. 1.2.1 This specification is for evaluating the acceptability of SO 2and NO xcontinuous emission monitoring systems (CEMS) at the time of installation or soon after and whenever specified in the regulations. The CEMS may include, for certain stationary sources, a diluent (O 2or CO 2 ) monitor. 1.2.2 This specification is not designed to evaluate the installed CEMS performance over an extended period of time nor does it identify specific calibration techniques and other auxiliary procedures to assess the CEMS performance. The source owner or operator is responsible to calibrate, maintain, and operate the CEMS properly. The1536

Administrator may require, under Section 114 of the Act, the operator to conduct CEMS performance evaluations at other times besides the initial test to evaluate the CEMS performance. See 40 CFR Part 60, §60.13(c). 2.0 Summary of Performance Specification. Procedures for measuring CEMS relative accuracy and calibration drift are outlined. CEMS installation and measurement location specifications, equipment specifications, performance specifications, and data reduction procedures are included. Conformance of the CEMS with the Performance Specification is determined. 3.0 Definitions. 3.1 Calibration Drift (CD) means the difference in the CEMS output readings from the established reference value after a stated period of operation during which no unscheduled maintenance, repair, or adjustment took place. 3.2 Centroidal Areameans a concentric area that is geometrically similar to the stack or duct cross section andis no greater than l percent of the stack or duct crosssectional area. 3.3 Continuous Emission Monitoring Systemmeans the total equipment required for the determination of a gas concentration or emission rate. The sample interface,1537

pollutant analyzer, diluent analyzer, and data recorder are the major subsystems of the CEMS. 3.4 Data Recordermeans that portion of the CEMS that provides a permanent record of the analyzer output. The data recorder may include automatic data reduction capabilities. 3.5 Diluent Analyzermeans that portion of the CEMS that senses the diluent gas ( i.e. , CO 2or O 2 ) and generates an output proportional to the gas concentration. 3.6 Path CEMSmeans a CEMS that measures the gas concentration along a path greater than 10 percent of the equivalent diameter of the stack or duct cross section. 3.7 Point CEMSmeans a CEMS that measures the gas concentration either at a single point or along a path equal to or less than 10 percent of the equivalent diameter of the stack or duct cross section. 3.8 Pollutant Analyzermeans that portion of the CEMS that senses the pollutant gas and generates an output proportional to the gas concentration. 3.9 Relative Accuracy (RA) means the absolute mean difference between the gas concentration or emission rate determined by the CEMS and the value determined by the reference method (RM), plus the 2.5 percent error confidence1538

coefficient of a series of tests, divided by the mean of the RM tests or the applicable emission limit. 3.10 Sample Interface means that portion of the CEMS used for one or more of the following: sample acquisition, sample delivery, sample conditioning, or protection of the monitor from the effects of the stack effluent. 3.11 Span Value means the concentration specified for the affected source category in an applicable subpart of the regulations that is used to set the calibration gas concentration and in determining calibration drift. 4.0 Interferences. [Reserved] 5.0 Safety. The procedures required under this performance specification may involve hazardous materials, operations, and equipment. This performance specification may not address all of the safety problems associated with these procedures. It is the responsibility of the user to establish appropriate safety and health practices and determine the applicable regulatory limitations prior to performing these procedures. The CEMS user's manual and materials recommended by the reference method should be consulted for specific precautions to be taken. 6.0 Equipment and Supplies. 6.1 CEMS Equipment Specifications.1539 6.1.1 Data Recorder Scale. The CEMS data recorder output range must include zero and a high-level value. The high-level value is chosen by the source owner or operator and is defined as follows: 6.1.1.1 For a CEMS intended to measure an uncontrolled emission ( e.g. , SO 2measurements at the inlet of a flue gas desulfurization unit), the high-level value should be between 1.25 and 2 times the maximum potential emission level over the appropriate averaging time, unless otherwise specified in an applicable subpart of the regulations. 6.1.1.2 For a CEMS installed to measure controlled emissions or emissions that are in compliance with an applicable regulation, the high-level value between 1.5 times the pollutant concentration corresponding to the emission standard level and the span value given in the applicable regulations is adequate. 6.1.1.3 Alternative high-level values may be used, provided the source can measure emissions which exceed the full-scale limit in accordance with the requirements of applicable regulations. 6.1.1.4 If an analog data recorder is used, the data recorder output must be established so that the high-level value would read between 90 and 100 percent of the data1540

recorder full scale. (This scale requirement may not be applicable to digital data recorders.) The zero and high level calibration gas, optical filter, or cell values should be used to establish the data recorder scale. 6.1.2 The CEMS design should also allow thedetermination of calibration drift at the zero and highlevel values. If this is not possible or practical, the design must allow these determinations to be conducted at a low-level value (zero to 20 percent of the high-level value) and at a value between 50 and 100 percent of the high-level value. In special cases, the Administrator may approve a single-point calibration-drift determination. 6.2 Other equipment and supplies, as needed by the applicable reference method(s) (see Section 8.4.2 of this Performance Specification), may be required. 7.0 Reagents and Standards. 7.1 Reference Gases, Gas Cells, or Optical Filters. As specified by the CEMS manufacturer for calibration of the CEMS (these need not be certified). 7.2 Reagents and Standards. May be required as needed by the applicable reference method(s) (see Section 8.4.2 of this Performance Specification). 8.0 Performance Specification Test Procedure.1541 8.1 Installation and Measurement Location Specifications. 8.1.1 CEMS Installation. Install the CEMS at an accessible location where the pollutant concentration or emission rate measurements are directly representative or can be corrected so as to be representative of the total emissions from the affected facility or at the measurement location cross section. Then select representative measurement points or paths for monitoring in locations that the CEMS will pass the RA test (see Section 8.4). If the cause of failure to meet the RA test is determined to be the measurement location and a satisfactory correction technique cannot be established, the Administrator may require the CEMS to be relocated. Suggested measurement locations and points or paths that are most likely to provide data that will meet the RA requirements are listed below. 8.1.2 CEMS Measurement Location. It is suggested that the measurement location be (1) at least two equivalent diameters downstream from the nearest control device, the point of pollutant generation, or other point at which a change in the pollutant concentration or emission rate may occur and (2) at least a half equivalent diameter upstream from the effluent exhaust or control device. 8.1.2.1 Point CEMS. It is suggested that the measurement point be (1) no less than 1.0 meter (3.3 ft)1542

from the stack or duct wall or (2) within or centrally located over the centroidal area of the stack or duct cross section. 8.1.2.2 Path CEMS. It is suggested that the effective measurement path (1) be totally within the inner area bounded by a line 1.0 meter (3.3 ft) from the stack or duct wall, or (2) have at least 70 percent of the pathwithin the inner 50 percent of the stack or duct crosssectional area, or (3) be centrally located over any part of the centroidal area. 8.1.3 Reference Method Measurement Location and Traverse Points. 8.1.3.1 Select, as appropriate, an accessible RM measurement point at least two equivalent diameters downstream from the nearest control device, the point of pollutant generation, or other point at which a change in the pollutant concentration or emission rate may occur, and at least a half equivalent diameter upstream from the effluent exhaust or control device. When pollutant concentration changes are due solely to diluent leakage ( e.g. , air heater leakages) and pollutants and diluents are simultaneously measured at the same location, a half diameter may be used in lieu of two equivalent diameters. The CEMS and RM locations need not be the same.1543 8.1.3.2 Select traverse points that assure acquisition of representative samples over the stack or duct cross section. The minimum requirements are as follows: Establish a "measurement line" that passes through the centroidal area and in the direction of any expected stratification. If this line interferes with the CEMS measurements, displace the line up to 30 cm (12 in.) (or 5 percent of the equivalent diameter of the cross section, whichever is less) from the centroidal area. Locate three traverse points at 16.7, 50.0, and 83.3 percent of the measurement line. If the measurement line is longer than 2.4 meters (7.8 ft) and pollutant stratification is not expected, the three traverse points may be located on the line at 0.4, 1.2, and 2.0 meters from the stack or duct wall. This option must not be used after wet scrubbers or at points where two streams with different pollutant concentrations are combined. If stratification is suspected, the following procedure is suggested. For rectangular ducts, locate at least nine sample points in the cross section such that sample points are the centroids of similarly-shaped, equal area divisions of the cross section. Measure the pollutant concentration, and, if applicable, the diluent concentration at each point using appropriate reference methods or other appropriate instrument methods that give responses relative to pollutant concentrations.1544

Then calculate the mean value for all sample points. For circular ducts, conduct a 12-point traverse (i.e., six points on each of the two perpendicular diameters) locating the sample points as described in 40 CFR 60, Appendix A, Method 1. Perform the measurements and calculations as described above. Determine if the mean pollutant concentration is more than 10% different from any single point. If so, the cross section is considered to be stratified, and the tester may not use the alternative traverse point locations (...0.4, 1.2, and 2.0 meters from the stack or duct wall.) but must use the three traverse points at 16.7, 50.0, and 83.3 percent of the entire measurement line. Other traverse points may be selected, provided that they can be shown to the satisfaction of the Administrator to provide a representative sample over the stack or duct cross section. Conduct all necessary RM tests within 3 cm (1.2 in.) of the traverse points, but no closer than 3 cm (1.2 in.) to the stack or duct wall. 8.2 Pretest Preparation. Install the CEMS, prepare the RM test site according to the specifications in Section 8.1, and prepare the CEMS for operation according to the manufacturer's written instructions. 8.3 Calibration Drift Test Procedure. 8.3.1 CD Test Period. While the affected facility is operating at more than 50 percent of normal load, or as1545

specified in an applicable subpart, determine the magnitude of the CD once each day (at 24-hour intervals) for 7 consecutive days according to the procedure given in Sections 8.3.2 through 8.3.4. 8.3.2 The purpose of the CD measurement is to verify the ability of the CEMS to conform to the established CEMS calibration used for determining the emission concentration or emission rate. Therefore, if periodic automatic or manual adjustments are made to the CEMS zero and calibration settings, conduct the CD test immediately before these adjustments, or conduct it in such a way that the CD can be determined. 8.3.3 Conduct the CD test at the two points specified in Section 6.1.2. Introduce to the CEMS the reference gases, gas cells, or optical filters (these need not be certified). Record the CEMS response and subtract this value from the reference value (see example data sheet in Figure 2-1). 8.4 Relative Accuracy Test Procedure. 8.4.1 RA Test Period. Conduct the RA test according to the procedure given in Sections 8.4.2 through 8.4.6 while the affected facility is operating at more than 50 percent of normal load, or as specified in an applicable subpart. The RA test may be conducted during the CD test period.1546 8.4.2 Reference Methods. Unless otherwise specified in an applicable subpart of the regulations, Methods 3B, 4, 6, and 7, or their approved alternatives, are the reference methods for diluent (O 2and CO 2 ), moisture, SO 2 , and NO x , respectively. 8.4.3 Sampling Strategy for RM Tests. Conduct the RM tests in such a way that they will yield results representative of the emissions from the source and can be correlated to the CEMS data. It is preferable to conduct the diluent (if applicable), moisture (if needed), and pollutant measurements simultaneously. However, diluent and moisture measurements that are taken within an hour of the pollutant measurements may be used to calculate dry pollutant concentration and emission rates. In order to correlate the CEMS and RM data properly, note the beginning and end of each RM test period of each run (including the exact time of day) on the CEMS chart recordings or other permanent record of output. Use the following strategies for the RM tests: 8.4.3.1 For integrated samples ( e.g. , Methods 6 and Method 4), make a sample traverse of at least 21 minutes, sampling for an equal time at each traverse point (see Section 8.1.3.2 for discussion of traverse points.1547 8.4.3.2 For grab samples ( e.g. , Method 7), take one sample at each traverse point, scheduling the grab samples so that they are taken simultaneously (within a 3-minute period) or at an equal interval of time apart over the span of time the CEM pollutant is measured. A test run for grab samples must be made up of at least three separate
measurements. NOTE: At times, CEMS RA tests are conducted during new source performance standards performance tests. In these cases, RM results obtained during CEMS RA tests may be used to determine compliance as long as the source and test conditions are consistent with the applicable regulations. 8.4.4 Number of RM Tests. Conduct a minimum of nine sets of all necessary RM test runs.
NOTE: More than nine sets of RM tests may be performed. If this option is chosen, a maximum of three sets of the test results may be rejected so long as the total number of test results used to determine the RA is greater than or equal to nine. However, all data must be reported, including the rejected data. 8.4.5 Correlation of RM and CEMS Data. Correlate the CEMS and the RM test data as to the time and duration by first determining from the CEMS final output (the one used for reporting) the integrated average pollutant1548

concentration or emission rate for each pollutant RM test period. Consider system response time, if important, and confirm that the pair of results are on a consistent moisture, temperature, and diluent concentration basis. Then, compare each integrated CEMS value against the corresponding average RM value. Use the following guidelines to make these comparisons. 8.4.5.1 If the RM has an integrated sampling technique, make a direct comparison of the RM results and CEMS integrated average value. 8.4.5.2 If the RM has a grab sampling technique, first average the results from all grab samples taken during the test run, and then compare this average value against the integrated value obtained from the CEMS chart recording or output during the run. If the pollutant concentration is varying with time over the run, the arithmetic average of the CEMS value recorded at the time of each grab sample may be used. 8.4.6 Calculate the mean difference between the RM and CEMS values in the units of the emission standard, the standard deviation, the confidence coefficient, and the relative accuracy according to the procedures in Section 12.0. 8.5 Reporting. At a minimum (check with the appropriate regional office, State, or Local agency for1549

additional requirements, if any), summarize in tabular form the results of the CD tests and the RA tests or alternative RA procedure, as appropriate. Include all data sheets, calculations, charts (records of CEMS responses), cylinder gas concentration certifications, and calibration cell response certifications (if applicable) necessary to confirm that the performance of the CEMS met the performance specifications. 9.0 Quality Control. [Reserved] 10.0 Calibration and Standardization. [Reserved] 11.0 Analytical Procedure. Sample collection and analysis are concurrent for this Performance Specification (see Section 8.0). Refer to the RM for specific analytical procedures. 12.0 Calculations and Data Analysis. Summarize the results on a data sheet similar to that shown in Figure 2-2 (in Section 18.0). 12.1 All data from the RM and CEMS must be on a consistent dry basis and, as applicable, on a consistent diluent basis and in the units of the emission standard. Correct the RM and CEMS data for moisture and diluent as follows: 12.1.1 Moisture Correction (as applicable). Correct each wet RM run for moisture with the corresponding Method 41550

Concentration ( dry ) ' Concentration ( wet ) ( 1

& B ws ) Eq. 2-1

ppm ( corr ) ' ppm ( uncorr ) [ 20

. 9

& 7

. 0 20

. 9

& % O 2 ( dry ) ] Eq. 2-2

d ' 1 n j n
i ' 1 d i Eq. 2-3

j n
i ' 1 d i ' Algebraic summation of the individual differences d i . data; correct each wet CEMS run using the corresponding CEMS moisture monitor date using Equation 2-1.

12.1.2 Correction to Units of Standard (as applicable). Correct each dry RM run to the units of the emission standard with the corresponding Method 3B data; correct each dry CEMS run using the corresponding CEMS diluent monitor data as follows: 12.1.2.1 Correct to Diluent Basis. The following is an example of concentration (ppm) correction to 7% oxygen.

The following is an example of mass/gross calorific value (lbs/million Btu) correction.

lbs/MMBtu = Conc (dry) (F-factor) (20.9/20.9- %0 2 ) 12.2 Arithmetic Mean. Calculate the arithmetic mean of the difference, d, of a data set as follows:

where: n = Number of data points.1551

S d ' j

n
i ' 1 d 2 i & j n
i ' 1 d i 2

n n
& 1 1

2 Eq. 2-4

CC ' t 0

. 975 S d

n Eq. 2-5

RA ' d % CC

RM x 100 Eq. 2-6 12.3 Standard Deviation. Calculate the standard deviation, S d , as follows:

12.4 Confidence Coefficient. Calculate the 2.5 percent error confidence coefficient (one-tailed), CC, as follows:

where: t 0.975= t-value (see Table 2-1). 12.5 Relative Accuracy. Calculate the RA of a set of data as follows:

where: | d b | = Absolute value of the mean differences (from

Equation 2-3). |CC|= Absolute value of the confidence coefficient

(from Equation 2-3).1552
R  ̄ M  ̄ = Average RM value. In cases where the

average emissions for the test are less than 50 percent of the applicable standard, substitute the emission standard value in the denominator of Eq. 2-6 in place of R  ̄ M  ̄
. In all other cases, use R  ̄ M  ̄
. 13.0 Method Performance. 13.1 Calibration Drift Performance Specification. The CEMS calibration must not drift or deviate from the reference value of the gas cylinder, gas cell, or optical filter by more than 2.5 percent of the span value. If the CEMS includes pollutant and diluent monitors, the CD must be determined separately for each in terms of concentrations (See Performance Specification 3 for the diluent specifications), and none of the CDs may exceed the specification. 13.2 Relative Accuracy Performance Specification. The RA of the CEMS must be no greater than 20 percent when
R  ̄ M  ̄ is used in the denominator of Eq. 2-6 (average emissions during test are greater than 50 percent of the emission standard) or 10 percent when the applicable emission standard is used in the denominator of Eq. 2-6 (average emissions during test are less than 50 percent of the emission standard).1553 13.3 For instruments that use common components to measure more than one effluent gas constituent, all channels must simultaneously pass the RA requirement, unless it can be demonstrated that any adjustments made to one channel did not affect the others. 14.0 Pollution Prevention. [Reserved] 15.0 Waste Management. [Reserved] 16.0 Alternative Procedures. Paragraphs 60.13(j)(1) and (2) of 40 CFR part 60 contain criteria for which the reference method procedure for determining relative accuracy (see Section 8.4 of this Performance Specification) may be waived and the following procedure substituted. 16.1 Conduct a complete CEMS status check following the manufacturer's written instructions. The check should include operation of the light source, signal receiver, timing mechanism functions, data acquisition and data reduction functions, data recorders, mechanically operated functions (mirror movements, zero pipe operation, calibration gas valve operations, etc.), sample filters, sample line heaters, moisture traps, and other related functions of the CEMS, as applicable. All parts of the CEMS shall be functioning properly before proceeding to the alternative RA procedure.1554 16.2 Alternative RA Procedure. 16.2.1 Challenge each monitor (both pollutant and diluent, if applicable) with cylinder gases of known concentrations or calibration cells that produce known responses at two measurement points within the ranges shown in Table 2-2 (Section 18). 16.2.2 Use a separate cylinder gas (for point CEMS only) or calibration cell (for path CEMS or where compressed gas cylinders can not be used) for measurement points 1 and 2. Challenge the CEMS and record the responses three times at each measurement point. The Administrator may allow dilution of cylinder gas using the performance criteria in Test Method 205, 40 CFR Part 51, Appendix M. Use the average of the three responses in determining relative
accuracy. 16.2.3 Operate each monitor in its normal sampling mode as nearly as possible. When using cylinder gases, pass the cylinder gas through all filters, scrubbers, conditioners, and other monitor components used during normal sampling and as much of the sampling probe as practical. When using calibration cells, the CEMS components used in the normal sampling mode should not be by-passed during the RA determination. These include light sources, lenses, detectors, and reference cells. The CEMS should be challenged at each measurement point for a1555

sufficient period of time to assure adsorption-desorption reactions on the CEMS surfaces have stabilized. 16.2.4 Use cylinder gases that have been certified by comparison to National Institute of Standards and Technology (NIST) gaseous standard reference material (SRM) or NIST/EPA approved gas manufacturer's certified reference material (CRM) (See Reference 2 in Section 17.0) following EPA Traceability Protocol Number 1 (See Reference 3 in Section 17.0). As an alternative to Protocol Number 1 gases, CRM's may be used directly as alternative RA cylinder gases. A list of gas manufacturers that have prepared approved CRM's is available from EPA at the address shown in Reference 2. Procedures for preparation of CRM's are described in Reference 2. 16.2.5 Use calibration cells certified by the manufacturer to produce a known response in the CEMS. The cell certification procedure shall include determination of CEMS response produced by the calibration cell in direct comparison with measurement of gases of known concentration. This can be accomplished using SRM or CRM gases in a laboratory source simulator or through extended tests using reference methods at the CEMS location in the exhaust stack. These procedures are discussed in Reference 4 in Section 17.0. The calibration cell certification procedure is subject to approval of the Administrator.1556

RA ' /

0 0 0 /

0 0 0 d AC 100 # 15 percent Eq. 2-7 16.3 The differences between the known concentrations of the cylinder gases and the concentrations indicated by the CEMS are used to assess the accuracy of the CEMS. The calculations and limits of acceptable relative accuracy are as follows: 16.3.1 For pollutant CEMS:

where: d b = Average difference between responses and the

concentration/responses (see Section 16.2.2). AC = The known concentration/response of the

cylinder gas or calibration cell. 16.3.2 For diluent CEMS: RA = | d b | < O.7 percent O 2or CO 2 , as applicable.
NOTE: Waiver of the relative accuracy test in favor of the alternative RA procedure does not preclude the requirements to complete the CD tests nor any other requirements specified in an applicable subpart for reporting CEMS data and performing CEMS drift checks or audits. 17.0 References.1557 1. Department of Commerce. Experimental Statistics. Handbook 91. Washington, D.C. p. 3-31, paragraphs

3-3.1.4. 2. "A Procedure for Establishing Traceability of Gas Mixtures to Certain National Bureau of Standards Standard Reference Materials." Joint publication by NBS and EPA. EPA 600/7-81-010. Available from U.S. Environmental Protection Agency, Quality Assurance Division (MD-77), Research Triangle Park, North Carolina 27711. 3. "Traceability Protocol for Establishing True Concentrations of Gases Used for Calibration and Audits of Continuous Source Emission Monitors. (Protocol Number 1)." June 1978. Protocol Number 1 is included in the Quality Assurance Handbook for Air Pollution Measurement Systems, Volume III, Stationary Source Specific Methods . EPA-600/4- 77-027b. August 1977. 4. "Gaseous Continuous Emission Monitoring Systems - Performance Specification Guidelines for SO 2 , NO x , CO 2 , O 2 , and TRS." EPA-450/3-82-026. Available from the U.S. EPA, Emission Measurement Center, Emission Monitoring and Data Analysis Division (MD-19), Research Triangle Park, North Carolina 27711. 18.0 Tables, Diagrams, Flowcharts, and Validation Data.1558 TABLE 2-1. t-VALUES.

n a t 0.975 n a t 0.975 n a t 0.975 2 12.706 7 2.447 12 2.201 3 4.303 8 2.365 13 2.179 4 3.182 9 2.306 14 2.160 5 2.776 10 2.262 15 2.145 6 2.571 11 2.228 16 2.131

a The values in this table are already corrected for n-1 degrees of

freedom. Use n equal to the number of individual values.1559 Table 2-2. Measurement Range. Measurement Point Pollutant

Monitor Diluent Monitor for CO 2 O 2 1 20-30% of

span value 5-8% by volume 4-6% by

volume 2 50-60% of

span value 10-14% by volume 8-12% by

volume

Lowlevel Day Date

and Time Calibration

Value (C) Monitor

Value (M) Difference

(C-M) Percent of

span value (C-M)/Span Value x 100

Highlevel

Figure 2-1. Calibration Drift Determination

.1560

Run No. Date

and Time SO 2 b NO x a

CO 2or O 2 a SO 2 a NO x

RM CEMS Diff RM CEMS Diff RM CEMS RM CEM S Diff RM CEMS Diff

ppmc ppmc % c % c mass/GCV mass/GCV

1 2 3 4 5 6 7 8 9 10 11 12 Average Confidence Interval Accuracy aFor steam generators bAverage of three samples

cMake sure that RM and CEMS data are on a consistent basis, either wet or dry. Figure 2-2. Relative Accuracy Determination.