where:
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:
2.1.7.5 Calibration Error. Calculate CE using Equation 5.
where:
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.
2.2.2.6 Response Time. The time interval between the start of a step change in the system input (e.g., change of calibration gas) and the time when the data recorder displays 95% of the final value.
2.2.2.7 Accuracy. A measurement of agreement between a measured value and an accepted or true value, expressed as the percentage difference between the true and measured values relative to the true value. For these performance specifications, accuracy is checked by conducting a calibration error (CE) test.
2.2.2.8 Calibration Error (CE). The difference between the concentration indicated by the CEMS and the known concentration of the cylinder gas. A CE test procedure is performed to document the accuracy and linearity of the monitoring equipment over the entire measurement range.
2.2.2.9 Performance Specification Test (PST) Period. The period during which CD, CE, and response time tests are conducted.
2.2.2.10 Centroidal Area. A concentric area that is geometrically similar to the stack or duct cross section and is no greater than one percent of the stack or duct cross-sectional area.
2.2.3 Installation and Measurement Location
Specifications
2.2.3.1 CEMS Installation and Measurement Locations. The CEMS shall be installed in a location in which measurements representative of the source's emissions can be obtained. The optimum location of the sample interface for the CEMS is determined by a number of factors, including ease of access for calibration and maintenance, the degree to which sample conditioning will be required, the degree to which it represents total emissions, and the degree to which it represents the combustion situation in the firebox. The location should be as free from in-leakage influences as possible and reasonably free from severe flow disturbances. The sample location should be at least 2 equivalent duct diameters downstream from the nearest control device, point of pollutant generation, or other point at which a change in the pollutant concentration or emission rate occurs and at least 0.5 diameter upstream from the exhaust or control device. The equivalent duct diameter is calculated as per
40 CFR part 60, Appendix A, method 1, section 2.1, incorporated by reference in s.
NR 660.11. If these criteria are not achievable or if the location is otherwise less than optimum, the possibility of stratification should be investigated as described in section 2.2.3.2. The measurement point shall be within the centroidal area of the stack or duct cross section.
2.2.3.2 Stratification Test Procedure. Stratification is defined as a difference in excess of 10% between the average concentration in the duct or stack and the concentration at any point more than 1.0 meter from the duct or stack wall. To determine whether effluent stratification exists, a dual probe system should be used to determine the average effluent concentration while measurements at each traverse point are being made. One probe, located at the stack or duct centroid, is used as a stationary reference point to indicate the change in effluent concentration over time. The second probe is used for sampling at the traverse points specified in
40 CFR part 60 Appendix A, method 1, incorporated by reference in s.
NR 660.11. The monitoring system samples sequentially at the reference and traverse points throughout the testing period for 5 minutes at each point.
2.2.4 CEMS Performance and Equipment Specifications
If this method is applied in highly explosive areas, caution and care shall be exercised in choice of equipment and installation.
2.2.4.1 Flame Ionization Detector (FID) Analyzer. A heated FID analyzer capable of meeting or exceeding these specifications. Heated systems shall maintain the temperature of the sample gas between 150 °C (300 °F) and 175 °C (350 °F) throughout the system. This requires all system components such as the probe, calibration valve, filter, sample lines, pump, and the FID to be kept heated at all times such that no moisture is condensed out of the system.
Note: As specified in the regulations, unheated HC CEMs may be considered an acceptable interim alternative monitoring technique. For additional notes, see section 2.2.10. The essential components of the measurement system are described below:
2.2.4.1.1 Sample Probe. Stainless steel, or equivalent, to collect a gas sample from the centroidal area of the stack cross-section.
2.2.4.1.2 Sample Line. Stainless steel or Teflon tubing to transport the sample to the analyzer.
Note: Mention of trade names or specific products does not constitute endorsement by the department.
2.2.4.1.3 Calibration Valve Assembly. A heated 3-way valve assembly to direct the zero and calibration gases to the analyzer is recommended. Other methods, such as quick-connect lines, to route calibration gas to the analyzers are applicable.
2.2.4.1.4 Particulate Filter. An in-stack or out-of-stack sintered stainless steel filter is recommended if exhaust gas particulate loading is significant. An out-of-stack filter shall be heated.
2.2.4.1.5 Fuel. The fuel specified by the manufacturer (e.g., 40% hydrogen/60% helium, 40% hydrogen/60% nitrogen gas mixtures, or pure hydrogen) should be used.
2.2.4.1.6 Zero Gas. High purity air with less than 0.1 parts per million by volume (ppm) HC as methane or carbon equivalent or less than 0.1% of the span value, whichever is greater.
2.2.4.1.7 Calibration Gases. Appropriate concentrations of propane gas (in air or nitrogen). Preparation of the calibration gases should be done according to the procedures in EPA Protocol 1, incorporated by reference in s.
NR 660.11. In addition, the manufacturer of the cylinder gas should provide a recommended shelf life for each calibration gas cylinder over which the concentration does not change by more than
±2% from the certified value.
2.2.4.2 CEMS Span Value. 100 ppm propane.
2.2.4.3 Daily Calibration Gas Values. The owner or operator shall choose calibration gas concentrations that include zero and high-level calibration values.
2.2.4.3.1 The zero level may be between 0 and 20 ppm (0 and 20% of the span value).
2.2.4.3.2 The high-level concentration shall be between 50 and 90 ppm (50 and 90% of the span value).
2.2.4.4 Data Recorder Scale. The strip chart recorder, computer, or digital recorder shall be capable of recording all readings within the CEMS's measurement range and shall have a resolution of 0.5 ppm (0.5% of span value).
2.2.4.5 Response Time. The response time for the CEMS may not exceed 2 minutes to achieve 95% of the final stable value.
2.2.4.6 Calibration Drift. The CEMS shall allow the determination of CD at the zero and high-level values. The CEMS calibration response may not differ by more than ±3 ppm (±3% of the span value) after each 24-hour period of the 7-day test at both zero and high levels.
2.2.4.7 Calibration Error. The mean difference between the CEMS and reference values at all 3 test points listed below shall be no greater than 5 ppm (±5% of the span value).
2.2.4.7.1 Zero Level. Zero to 20 ppm (0 to 20% of span value).
2.2.4.7.2 Mid-Level. 30 to 40 ppm (30 to 40% of span value).
2.2.4.7.3 High-Level. 70 to 80 ppm (70 to 80% of span value).
2.2.4.8 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.
2.2.4.9 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.
2.2.4.10 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, necessary corrections shall be made and the performance tests repeated.
2.2.5 Performance Specification Test (PST) Periods
2.2.5.1 Pretest Preparation Period. Install the CEMS, prepare the PTM test site according to the specifications in section 2.2.3, 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.
2.2.5.2 Calibration Drift Test Period. While the facility is operating under normal conditions, determine the magnitude of the CD at 24-hour intervals for 7 consecutive days according to the procedure given in section 2.2.6.1. 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 CD test when the unit resumes operation.
2.2.5.3 Calibration Error Test and Response Time Test Periods. Conduct the CE and response time tests during the CD test period.
2.2.6 Performance Specification Test Procedures
2.2.6.1 Calibration Drift Test.
2.2.6.1.1 Sampling Strategy. Conduct the CD test at 24-hour intervals for 7 consecutive days using calibration gases at the 2 daily concentration levels specified in section 2.2.4.3. Introduce the 2 calibration gases into the sampling system as close to the sampling probe outlet as practical. The gas shall pass through all CEM 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 3 ppm.
2.2.6.1.2 Calculations. Summarize the results on a data sheet. An example is shown in Figure 2.2-1. Calculate the differences between the CEMS responses and the reference values.
2.2.6.2 Response Time. The entire system including sample extraction and transport, sample conditioning, gas analyses, and the data recording is checked with this procedure.
2.2.6.2.1 Introduce the calibration gases at the probe as near to the sample location as possible. Introduce the zero gas into the system. When the system output has stabilized (no change greater than 1 percent of full scale for 30 sec), 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.
2.2.6.2.2 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.
