2.1.4.7 Calibration Error. The mean difference between the CEMS and reference values at all 3 test points (see Table 2.1-3) shall be no greater than 5% of span value for CO monitors (i.e., 10 ppm CO for low range Tier I CO analyzers and 150 ppm CO for high range CO analyzers) and 0.5% for O2 analyzers.
2.1.4.8 Measurement and Recording Frequency. The sample to be analyzed shall pass through the measurement section of the analyzer without interruption. The detector shall measure the sample concentration at least once every 15 seconds. An average emission rate shall be computed and recorded at least once every 60 seconds.
2.1.4.9 Hourly Rolling Average Calculation. The CEMS shall calculate every minute an hourly rolling average, which is the arithmetic mean of the 60 most recent one-minute average values.
2.1.4.10 Retest. If the CEMS produces results within the specified criteria, the test is successful. If the CEMS does not meet one or more of the criteria, the necessary corrections shall be made and the performance tests repeated.
2.1.5 Test Periods
2.1.5.1 Pretest Preparation Period. Install the CEMS, prepare the PTM test site according to the specifications in section 2.1.3, and prepare the CEMS for operation and calibration according to the manufacturer’s written instructions. A pretest conditioning period similar to that of the 7-day CD test is recommended to verify the operational status of the CEMS.
2.1.5.2 Calibration Drift Test Period. While the facility is operating under normal conditions, determine the CD at 24-hour intervals for 7 consecutive days according to the procedure given in section 2.1.6.1. All CD determinations shall be made following a 24-hour period during which no unscheduled maintenance, repair, or adjustment takes place. If the combustion unit is taken out of service during the test period, record the onset and duration of the downtime and continue the calibration drift test when the unit resumes operation.
2.1.5.3 Relative Accuracy Test Period. Conduct the RA test according to the procedure in section 2.1.6.4 while the facility is operating under normal conditions. RA testing for CO and O2 shall be conducted simultaneously so that the results can be calculated for CO corrected to 7% O2. The RA test shall be conducted during the CD test period. It is emphasized that during the CD test period, no adjustments or repairs may be made to the CEMS other than routine calibration adjustments performed immediately following the daily CD determination.
2.1.5.4 Calibration Error Test and Response Time Test Periods. Conduct the CE and response time tests during the CD test period.
2.1.6 Performance Specification Test Procedures
2.1.6.1 Calibration Drift Test.
2.1.6.1.1 Sampling Strategy. Conduct the CD test for all monitors at 24-hour intervals for 7 consecutive days using calibration gases at the 2 (or 3, if applicable) concentration levels specified in section 2.1.4.2. Introduce the calibration gases into the sampling system as close to the sampling probe outlet as practical. The gas shall pass through all filters, scrubbers, conditioners, and other CEMS components used during normal sampling. 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. Record the CEMS response and subtract this value from the reference (calibration gas) value. To meet the specification, none of the differences shall exceed the limits specified in Table 2.1-1.
2.1.6.1.2 Calculations. Summarize the results on a data sheet. An example is shown in Figure 2.1-1. Calculate the differences between the CEMS responses and the reference values.
2.1.6.2 Response Time. Check the entire CEMS including sample extraction and transport, sample conditioning, gas analyses, and the data recording.
2.1.6.2.1 Introduce zero gas into the system. For extractive systems, introduce the calibration gases at the probe as near to the sample location as possible. For in-situ system, introduce the zero gas at a point such that all components active in the analysis are tested. When the system output has stabilized (no change greater than one percent of full scale for 30 seconds), switch to monitor stack effluent and wait for a stable value. Record the time (upscale response time) required to reach 95% of the final stable value.
2.1.6.2.2 Next, introduce a high-level calibration gas and repeat the above procedure. Repeat the entire procedure 3 times and determine the mean upscale and downscale response times. The longer of the 2 means is the system response time.
2.1.6.3 Calibration Error Test Procedure.
2.1.6.3.1 Sampling Strategy. Challenge each monitor (both low- and high-range CO and O2) with zero gas and EPA Protocol 1, incorporated by reference in s. NR 660.11, cylinder gases at 3 measurement points within the ranges specified in Table 2.1-3. 1For Tier II, the CE specifications for the low-range CO CEMS are 0-20%, 30-40%, and 70-80% of twice the license limit.
2.1.6.3.1.1 If a single measurement range is used, the calibration gases used in the daily CD checks (if they are Protocol 1 cylinder gases and meet the criteria in section 2.1.6.3.1) may be used for determining CE.
2.1.6.3.1.2 Operate each monitor in its normal sampling mode as nearly as possible. The calibration gas shall be injected into the sample system as close to the sampling probe outlet as practical and should pass through all CEMS components used during normal sampling. Challenge the CEMS 3 non-consecutive times at each measurement point and record the responses. The duration of each gas injection should be sufficient to ensure that the CEMS surfaces are conditioned.
2.1.6.3.2 Calculations. Summarize the results on a data sheet. An example data sheet is shown in Figure 2.1-2. Average the differences between the instrument response and the certified cylinder gas value for each gas. Calculate 3 CE results (5 CE results for a single-range CO CEMS) according to Equation 5 (section 2.1.7.5). No confidence coefficient is used in CE calculations.
2.1.6.4 Relative Accuracy Test Procedure.
2.1.6.4.1 Sampling Strategy for PTM tests. Conduct the PTM tests in such a way that they will yield measurements representative of the emissions from the source and can be correlated to the CEMS data. Although it is preferable to conduct the CO, diluent, and moisture (if needed) simultaneously, moisture measurements that are taken within a 60-minute period which includes the simultaneous CO and O2 measurements may be used to calculate the dry CO concentration.
Note: At times, CEMS RA tests may be conducted during incinerator performance tests. In these cases, PTM results obtained during CEMS RA tests may be used to determine compliance with incinerator emissions limits as long as the source and test conditions are consistent with the applicable regulations.
2.1.6.4.2 Performance Test Methods.
2.1.6.4.2.1 Unless otherwise specified in the regulations, method 3 or 3A and method 10, 10A, or 10B (40 CFR part 60, Appendix A, incorporated by reference in s. NR 660.11) are the test methods for O2 and CO, respectively. Make a sample traverse of at least 21 minutes, sampling for 7 minutes at each of 3 traverse points (see section 3.2). 2.1.6.4.2.2 When the installed CEMS uses a nondispersive infrared (NDIR) analyzer, method 10 shall use the alternative interference trap specified in section 10.1 of the method. An option, which may be approved by the department in certain cases, would allow the test to be conducted using method 10 without the interference trap. Under this option, a laboratory interference test is performed for the analyzer prior to the field test. The laboratory interference test includes the analysis of SO, NO, and CO calibration gases over the range of expected effluent concentrations. Acceptable performance is indicated if the CO analyzer response to each of the gases is less than one percent of the applicable measurement range of the analyzer.
2.1.6.4.3 Number of PTM Tests. Conduct a minimum of 9 sets of all necessary PTM tests. If more than 9 sets are conducted, a maximum of 3 sets may be rejected at the tester’s discretion. The total number of sets used to determine the RA shall be greater than or equal to 9. All data, including the rejected data, shall be reported.
2.1.6.4.4 Correlation of PTM and CEMS Data. The time and duration of each PTM test run and the CEMS response time should be considered in correlating the data. Use the CEMS final output (the one used for reporting) to determine an integrated average CO concentration for each PTM test run. Confirm that the pair of results are on a consistent moisture and O2 concentration basis. Each integrated CEMS value should then be compared against the corresponding average PTM value. If the CO concentration measured by the CEMS is normalized to a specified diluent concentration, the PTM results shall be normalized to the same value.
2.1.6.4.5 Calculations. Summarize the results on a data sheet. Calculate the mean of the PTM values and calculate the arithmetic differences between the PTM and the CEMS data sets. The mean of the differences, standard deviation, confidence coefficient, and CEMS RA should be calculated using Equations one through 4.
2.1.7 Equations
2.1.7.1 Arithmetic Mean (). Calculate of the difference of a data set using Equation one. where:
n = Number of data points.
= Algebraic sum of the individual differences di. When the mean of the differences of pairs of data is calculated, correct the data for moisture, if applicable.
2.1.7.2 Standard Deviation (Sd). Calculate Sd using Equation 2.
2.1.7.3 Confidence Coefficient (CC). Calculate the 2.5% error CC (one-tailed) using Equation 3.
where:
t0.975=t-value (see Table 2.1-4).
a The values in this table are already corrected for n-1 degrees of freedom. Use n equal to the number of individual values.
2.1.7.4 Relative Accuracy. Calculate the RA of a set of data using Equation 4.
where:
= Absolute value of the mean of the differences
(Equation one). = Absolute value of the confidence coefficient (Equation 3). = Average reference value. 2.1.7.5 Calibration Error. Calculate CE using Equation 5.
where:
= Mean difference between CEMS response and the known reference concentration. 2.1.8 Reporting
At a minimum, summarize in tabular form the results of the CD, RA, response time, and CE test, as appropriate. Include all data sheets, calculations, CEMS data records, and cylinder gas or reference material certifications.
2.1.9 Alternative Procedure
2.1.9.1 Alternative RA Procedure Rationale. Under some operating conditions, it may not be possible to obtain meaningful results using the RA test procedure. This includes conditions where consistent, very low CO emissions or low CO emissions interrupted periodically by short duration, high level spikes are observed. It may be appropriate in these circumstances to waive the PTM RA test and substitute the following procedure.
2.1.9.2 Alternative RA Procedure. 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, 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 the RA requirement can be waived. The instruments shall also have successfully passed the CE and CD requirements of the performance specifications. Substitution of the alternative procedure requires approval of the department.
2.1.10 Quality Assurance (QA)
Proper calibration, maintenance, and operation of the CEMS is the responsibility of the owner or operator. The owner or operator shall establish a QA program to evaluate and monitor CEMS performance. As a minimum, the QA program shall include:
2.1.10.1 A daily calibration check for each monitor. The calibration shall be adjusted if the check indicates the instrument’s CD exceeds the specification established in section 2.1.4.5. The gases shall be injected as close to the probe as possible to provide a check of the entire sampling system. If an alternative calibration procedure is desired (e.g., direct injections or gas cells), subject to department approval, the adequacy of this alternative procedure may be demonstrated during the initial 7-day CD test. Periodic comparisons of the 2 procedures are suggested.
2.1.10.2 A daily system audit. The audit shall include a review of the calibration check data, an inspection of the recording system, an inspection of the control panel warning lights, and an inspection of the sample transport and interface system (e.g., flowmeters, filters), as appropriate.
2.1.10.3 A quarterly calibration error (CE) test. Quarterly RA tests may be substituted for the CE test when approved by the department on a case-by-case basis.
2.1.10.4 An annual performance specification test.
2.1.11 References
1. Jahnke, James A. and G.J. Aldina, “Handbook: Continuous Air Pollution Source Monitoring Systems,” U.S. Environmental Protection Agency Technology Transfer, Cincinnati, Ohio 45268, EPA-625/6-79-005, June 1979.
2. “Gaseous Continuous Emissions Monitoring Systems-Performance Specification Guidelines for SO, NOx, CO, O, and TRS.” U.S. Environmental Protection Agency OAQPS, ESED, Research Triangle Park, North Carolina 27711, EPA-450/3-82-026, October 1982.
3. “Quality Assurance Handbook for Air Pollution Measurement Systems: Volume I. Principles.” U.S. Environmental Protection Agency ORD/EMSL, Research Triangle Park, North Carolina, 27711, EPA-600/9-76-006, December 1984.
4. Michie, Raymond, M. Jr., et. al., “Performance Test Results and Comparative Data for Designated Reference Methods for Carbon Monoxide,” U.S. Environmental Protection Agency ORD/EMSL, Research Triangle Park, North Carolina, 27711, EPA-600/S4-83-013, September 1982.
5. Ferguson, B.B., R.E. Lester, and W.J. Mitchell, “Field Evaluation of Carbon Monoxide and Hydrogen Sulfide Continuous Emission Monitors at an Oil Refinery,” U.S. Environmental Protection Agency, Research Triangle Park, North Carolina, 27711, EPA-600/4-82-054, August 1982.
2.2 Performance Specifications for Continuous Emission Monitoring of Hydrocarbons for Incinerators, Boilers,
and Industrial Furnaces Burning Hazardous Waste
2.2.1 Applicability and Principle
2.2.1.1 Applicability. These performance specifications apply to hydrocarbon (HC) continuous emission monitoring systems (CEMSs) installed on incinerators, boilers, and industrial furnaces burning hazardous waste. The specifications include procedures which are intended to be used to evaluate the acceptability of the CEMS at the time of its installation or whenever specified in regulations or licenses. The procedures are not designed to evaluate CEMS performance over an extended period of time. The source owner or operator is responsible for the proper calibration, maintenance, and operation of the CEMS at all times.
2.2.1.2 Principle. A gas sample is extracted from the source through a heated sample line and heated filter (except as provided by section 2.2.10) to a flame ionization detector (FID). Results are reported as volume concentration equivalents of propane. Installation and measurement location specifications, performance and equipment specifications, test and data reduction procedures, and brief quality assurance guidelines are included in the specifications. Calibration drift, calibration error, and response time tests are conducted to determine conformance of the CEMS with the specifications.
2.2.2 Definitions
2.2.2.1 Continuous Emission Monitoring System (CEMS). The total equipment used to acquire data, which includes sample extraction and transport hardware, analyzer, data recording and processing hardware, and software. The system consists of the following major subsystems:
2.2.2.1.1 Sample Interface. That portion of the system that is used for one or more of the following: Sample acquisition, sample transportation, sample conditioning, or protection of the analyzer from the effects of the stack effluent.
2.2.2.1.2 Organic Analyzer. That portion of the system that senses organic concentration and generates an output proportional to the gas concentration.
2.2.2.1.3 Data Recorder. That portion of the system that records a permanent record of the measurement values. The data recorder may include automatic data reduction capabilities.
2.2.2.2 Instrument Measurement Range. The difference between the minimum and maximum concentration that can be measured by a specific instrument. The minimum is often stated or assumed to be 0 and the range expressed only as the maximum.
2.2.2.3 Span or Span Value. Full scale instrument measurement range.
2.2.2.4 Calibration Gas. A known concentration of a gas in an appropriate diluent gas.
2.2.2.5 Calibration Drift (CD). 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 takes place. A CD test is performed to demonstrate the stability of the CEMS calibration over time.
