Method 7E—Determination of Nitrogen Oxides Emissions
Contents
1. 13 2 System Bias This specification is applicable to both the system bias and 2 point system calibration error tests described in Section 8 2 5 and 8 5 The pre and post run system bias or system calibration error must be within 5 0 percent of the calibration span for the low level and upscale calibration gases Alternatively the results are acceptable if Cs Cair is lt 0 5 ppmv or if cs Cy is lt 0 5 ppmv as applicable 13 3 Drift For each run the low level and upscale drift must be less than or equal to 3 0 percent of the calibration span The drift is also acceptable if the pre and post run bias or the pre and post run system calibration error responses do not differ by more than 0 5 ppmv at each gas concentration i e fomerrerans Cages lt 0 5 ppmv 13 4 Interference Check The total interference response i e the sum of the interference responses of all tested gaseous components must not be greater than 2 50 percent of the calibration span for the analyzer tested In summing the interferences use the larger of the absolute values obtained for the interferent tested with and without the pollutant present The results are also acceptable if the sum of the responses does not exceed 0 5 ppmv for a calibration span of 5 to 10 ppmv or 0 2 ppmv for a calibration span lt 5 ppmv LS 5 NOz to NO Conversion Efficiency Test as applicable T2. concentration for the run 22 times system response time Two times the system response time Within 10 of flow rate established during system response time check All points within 5 of mean for 1 point sampling 10 of mean for 3 point Alternatively all points within 0 5 ppm of mean for 1l point sampling 1 0 ppm of mean for 3 point sampling Multi hole probe with verifiable constant flow through all holes within 10 of mean flow rate requires Administrative All 1 minute averages within calibration span Run average Scalibration span Calibration and Standardization first run and when probe is removed from and re inserted into Each sample Prior to first run Each run What measurement system calibrations are required 1 The initial 3 point calibration error test as described in Section 8 2 3 and the system bias or system calibration error checks described in Section 8 2 5 are required and must meet the specifications in Section 13 before you start the test Make all necessary adjustments to calibrate the gas analyzer and data recorder Then after the test commences the system bias or system calibration error checks described in Section 8 5 are required before and after each run Your analyzer must be calibrated for all species of NOx that it detects Analyzers that measure NO and NO2 separately without using a converter must be calib
3. the targe t sampling rate or ratio between the end of the run and the bias or system t for all post run system point system calibration error checks you may the upscale gas last or a You may risk sampling for multiple runs before tem calibration error test at the conclusion of the runs A failed final test in this case will e all runs subsequent to the last passed test 1 If you do not pass the post run system bias or system on error check then the run is invalid You must diagnose and fix the problem and pass another calibration t Section 8 2 3 and system bias system calibration error check calibrati error tes repeating the run calibrati 2 After each run drift us low and checks are passed but or 2 point Section 8 2 5 before Record the system bias or system on error results on a form similar to Table 7E 2 specifica a 3 point tion in Section 13 3 calibration error test point sys tem calibration error calculate the low l ing Equation 7E 4 in Section upscale bias or 2 point system calibration error the low or upscale drift exceeds the ta are valid but t and a system bias or 2 t be performed and level and upscale A D0 If the post run the run dat check must passed before any more test runs are done 3 For dilution systems data from a 3 point system cal
4. y as practicable gas concentrations should be the highest expected at test sites Table 7E 4 Interference Response Date of Test Analyzer Type Model No Serial No Calibration Span Concentration Analyzer Test gas type ppm response of Calibration Span fF Table 7E 5 Manufacturer Stability Test Acceptance criteria Test description note 1 exceed 3 0 of analyzer range over a 12 hour run when measured with NOx present 80 of calibration span Fault Conditions Identify conditions which when they occur result in performance which is in compliance with the Manufacturer s Stability Test criteria These are to ted visually or electrically to the operator of the problem Insensitivity to 10 0 or manufacturers alternative Supply Voltage variation from nominal voltage must Variations produce a drift of lt 2 0 of calibration span for either zero or concentration 2 80 NOx present For a low medium and high calibration gas the difference between th manufacturer certified value and the analyzer response in direct calibration mode no more than 2 0 of calibration span Note 1 If the instrument is to be used as a Low Range analyzer all tests must be performed at a calibration span of 20 ppm or less
5. criteria in Section 13 0 are met 6 2 8 1 Dual Range Analyzers For certain applications a wide range of gas concentrations may be encountered necessitating the use of two measurement ranges Dual range analyzers are readily available for these applications These analyzers are often equipped with automated range switching capability so that when readings exceed the full scale of the low measurement range they ar recorded on the high range As an alternative to using a dual range analyzer you may use two segments of a single large measurement scale to serve as the low and high ranges In all cases when two ranges are used you must quality assure both ranges using the proper sets of calibration gases You must also meet the interference calibration error system bias and drift checks However we caution that when you use two segments of a large measurement scale for dual range purposes it may be difficult to meet the performance specifications on the low range due to signal to noise ratio considerations 6 2 8 2 Low Concentration Analyzer When an analyzer is routinely calibrated with a calibration span of 20 ppmv or less the manufacturer s stability test MST is required See Table 7E 5 for test parameters 6 2 9 Data Recording A strip chart recorder computerized data acquisition system digital recorder or data logger for recording
6. 3 Low Level Gas Less than 20 percent of the calibration span 7 1 4 Converter Efficiency Gas What reagents do I need for the converter efficiency test The converter efficiency gas is a manufacturer certified gas with a concentration sufficient to show NO2conversion at the concentrations encountered in the source A test gas concentration in the 40 to 60 ppm range is suggested but other concentrations may be more appropriate to specific sources For the test described in Section 8 2 4 1 NO2is required For the alternative converter efficiency tests in Section 16 2 NO is required 7 2 Interference Check What reagents do I need for the interference check Use the appropriate test gases listed in Table 7E 3 or others not listed that can potentially interfere as indicated by the test facility type instrument manufacturer etc to conduct the interferenc check These gases should be manufacturer certified but do not have to be prepared by the EPA traceability protocol 8 0 Sample Collection Preservation Storage and Transport Emission Test Procedure Since you are allowed to choose different options to comply with some of the performance criteria it is your responsibility to identify the specific options you have chosen to document that the performance criteria for that option have been met and to identify any deviations from the method 8 1 What sampling site and sampling points
7. The following is an updated copy of Method 7E after the 5 22 08 and 5 29 09 technical corrections Method 7E Determination of Nitrogen Oxides Emissions From Stationary Sources Instrumental Analyzer Procedure 1 0 Scope and Application What is Method 7E Method 7E is a procedure for measuring nitrogen oxides NOx in stationary source emissions using a continuous instrumental analyzer Quality assurance and quality control requirements are included to assure that you the tester collect data of known quality You must document your adherence to these specific requirements for equipment supplies sample collection and analysis calculations and data analysis This method does not completely describe all equipment supplies and sampling and analytical procedures you will need but refers to other methods for some of the details Therefore to obtain reliable results you should also have a thorough knowledge of these additional test methods which are found in appendix A to this part a Method 1 Sample and Velocity Traverses for Stationary Sources b Method 4 Determination of Moisture Content in Stack Gases 1 1 Analytes What does this method determine This method measures the concentration of nitrogen oxides as NO2 Sensitivity Nitric oxide NO 10102 43 9 Typically lt 2 of Nitrogen dioxide NO2 10102 44 0 Calibration Span 1 2 Applicability When is this method required The use o
8. interference test gases that are potentially encountered during a test see examples in Table 7E 3 into the analyzer separately or as mixtures Test the analyzer with the interference gas alone at the highest concentration expected at a test source and again with the interference gas and NOx at a representative NOx test concentration For analyzers measuring NOx greater than 20 ppm use a calibration gas with an NOx concentration of 80 to 100 ppm and set this concentration equal to the calibration span For analyzers measuring less than 20 ppm NOx select an NO concentration for the calibration span that reflects the emission levels at the sources to be tested and perform the interference check at that level Measure the total interference response of the analyzer to these gases in ppmv Record the responses and determine th interference using Table 7E 4 The specification in Section 13 4 must be met 2 A copy of this data including the date completed and Signed certification must be available for inspection at the test site and included with each test report This interference test is valid for the life of the instrument unless major analytical components e g the detector are replaced with different model parts If major components are replaced with different model parts the interference gas check must be repeated before returning the analyzer to s
9. me a condenser dryer or other suitable device is remove moisture continuously from the sample ga equipment needed to heat the probe or sample li condensation prior to the sample conditioning c also required For wet basis systems you must keep the sample dew point either by 1 Heating the sample lin sample transport components up to the inlet of and for hot wet extractive systems also heat analyzer or 2 by diluting the sample prior t using a dilution probe system The components r do either of the above are considered to be con equipment asurements required to s Any ne to avoid omponent is above its e and all the analyzer ing the o analysis equired to ditioning 6 2 5 Sampling Pump For systems similar to the one shown in Figure 7E 1 a leak free pump is needed to pull the sample gas through the system at a flow rate su minimize the response time of the measurement s pump may be constructed of any material that is reactive to the gas being sampled For dilution measurement systems an ejector pump eductor fficient to ystem The non type is used to create a vacuum that draws the sample through a critical orifice at a constant rate 6 2 6 Calibration Gas Manifold Prepare a system to allow the introduction of calibration gases either directly to the gas analyzer in direct calibration mode or into the measurement system at the probe in syste
10. measurement data may be used 7 0 Reagents and Standards 7 1 Calibration Gas What calibration gases do I need Your calibration gas must be NO in nitrogen and certified or recertified within an uncertainty of 2 0 percent in accordance with EPA Traceability Protocol for Assay and Certification of Gaseous Calibration Standards September 1997 as amended August 25 1999 EPA 600 R 97 121 Blended gases meeting the Traceability Protocol are allowed if the additional gas components are shown not to interfere with the analysis If a zero gas is used for the low level gas it must meet the requirements under the definition for zero air material in 40 CFR 72 2 The calibration gas must not be used after its expiration date Except for applications under part 75 of this chapter it is acceptable to prepare calibration gas mixtures from EPA Traceability Protocol gases in accordance with Method 205 in M to part 51 of this chapter For part 75 applications the use of Method 205 is subject to the approval of the Administrator The goal and recommendation for selecting calibration gases is to bracket the sample concentrations The following calibration gas concentrations are required 7 1 1 High Level Gas This concentration sets the calibration span and results in measurements being 20 to 100 percent of the calibration span 7 1 2 Mid Level Gas 40 to 60 percent of the calibration span 7 1
11. the MST requirements of Section 16 3 A copy of this information must be included in each test report Table 7E 5 lists the criteria to be met 3 13 Measurement System means all of the equipment used to determine the NOx concentration The measurement system comprises six major subsystems Sample acquisition sample transport sample conditioning calibration gas manifold gas analyzer and data recorder 3 14 Response Time means the time it takes the measurement system to respond to a change in gas concentration occurring at the sampling point when the system is operating normally at its target sample flow rate or dilution ratio 3 15 Run means a series of gas samples taken successively from the stack or duct A test normally consists of a specific number of runs 3 16 System Bias means the difference between a calibration gas measured in direct calibration mode and in system calibration mode System bias is determined befor and after each run at the low and mid or high concentration levels For dilution type systems pre and post run system calibration error is measured rather than system bias 3 17 System Calibration Error applies to dilution type systems and means the difference between the measured concentration of low mid or high level calibration gas and the certified concentration for each gas when introduced in system calibration mode For
12. as Mid level calibration GES ssssssssssssssso High level calibration GAS s ssissssssss t 2 View or download PDF Table 7E 2 System Bias Data Seurce Identification Test personnel Date Analyzer Model No Manufacturer Certified Cylinder Value indicate units Initial values Analyzer or System calibration error data for Sampling runs Analyzer Model No Serial No Calibration Span CS Analyzer calibrati on response indicate units Calibration Error percent of calibration span Absolute difference indicate units aefers to data from the analyzer calibration error test of a non dilution system Refers to data from a 3 point system calibration error test of a dilution system or System Calibration Error and Drift Run Number Calibration Span Response Time Serial No Final values Refers to the pre and post run system bias checks of a non dilution system 2 system View or download PDF Refers to the pre and post ron system calibration error checks of a dilution Table 7E 3 Example Interference Check Gas Concentrations Concentrations sample conditioning Potential interferent type 1 ol N gt gt any applicable gas may be eliminated or tested at a reduced level if the manufacturer has provided reliable means for limiting or scrubbing that gas to a specified level
13. calibration gases certifications have not expired This documentation should be available on site for inspection To the extent practicable select a high level gas concentration that will result in the measured emissions being between 20 and 100 percent of the calibration span 8 2 2 Measurement System Preparation How do I prepare my measurement system Assemble prepare and precondition the measurement system according to your standard operating procedure Adjust the system to achieve the correct sampling rate or dilution ratio as applicable 8 2 3 Calibration Error Test How do I confirm my analyzer calibration is correct After you have assembled prepared and calibrated your sampling system and analyzer you must conduct a 3 point analyzer calibration error test or a 3 point system calibration error test for dilution systems before the first run and again after any failed system bias test or 2 point system calibration error test for dilution systems or failed drift test Introduce the low mid and high level calibration gases sequentially For non dilution type measurement systems introduce the gases in direct calibration mode For dilution type measurement systems introduce the gases in system calibration mode 1 For non dilution systems you may adjust the system to maintain the correct flow rate at the analyzer during the test but you may
14. dilution type systems a 3 point system calibration error test is conducted in lieu of the analyzer calibration error test and 2 point system calibration error tests are conducted in lieu of system bias tests 3 18 System Calibration Mode means introducing the calibration gases into the measurement system at the probe upstream of the filter and all sample conditioning components 3 19 Test refers to the series of runs required by the applicable regulation 4 0 Interferences Note that interferences may vary among instruments and that instrument specific interferences must be evaluated through the interference test 5 0 Safety What safety measures should I consider when using this method This method may require you to work with hazardous materials and in hazardous conditions We encourage you to establish safety procedures before using the method Among other precautions you should become familiar with the safety recommendations in the gas analyzer user s manual Occupational Safety and Health Administration OSHA regulations concerning cylinder and noxious gases may apply Nitric oxide and NOzare toxic and dangerous gases Nitric oxide is immediately converted to NOs upon reaction with air Nitrogen dioxide is a highly poisonous and insidious gas Inflammation of the lungs from exposure may cause only slight pain or pass unnoticed but the resulting edema sev
15. do I select 8 1 1 Unless otherwise specified in an applicable regulation or by the Administrator when this method is used to determine compliance with an emission standard conduct a stratification test as described in Section 8 1 2 to determine the sampling traverse points to be used For performance testing of continuous emission monitoring systems follow the sampling site selection and traverse point layout procedures described in the appropriate performance specificat Performance Specifica 8 1 2 Determination of Stratification stratification tes appropriate number for multiple pollu tion or applicable regulation tion 2 t a of tan stratifica satisfies diameter appropriate leng interest Alterna at 16 7 Sample for a minimum of twice at each traverse point and mean NOx concentrations Section 8 individua tion tes To test for th tra concen you may 50 0 s246 1 point concentra tion at each concentra 5 0 per whicheve con sin percent o sidered unstrat gle point that most closely mat tion for all cent of tion at according to Table 1 1 or Table 1 2 tively passing through the centroidal and 83 3 percent the system response e g in appendix B to this part Perform a t each test site to determin sample traverse points ts or diluents at th t using
16. eral days later may cause death A concentration of 100 ppm is dangerous for even a short exposure and 200 ppm may be fatal Calibration gases must be handled with utmost care and with adequate ventilation Emission level exposure to these gases should be avoided 6 0 Equipment and Supplies The performance criteria in this method will be met or exceeded if you are properly using equipment designed for this application 6 1 What do I need for the measurement system You may use any equipment and supplies meeting the following specifications 1 Sampling system components that are not evaluated in the system bias or system calibration error test must be glass Teflon or stainless steel Other materials are potentially acceptable subject to approval by the Administrator 2 The interference calibration error and system bias criteria must be met 3 Sample flow rate must be maintained within 10 percent of the flow rate at which the system response time was measured 4 All system components excluding sample conditioning components if used must maintain the sample temperature above the moisture dew point Section 6 2 provides example equipment specifications for a NOx measurement system Figure 7E 1 is a diagram of an example dry basis measurement system that is likely to meet the method requirements and is provided as guidance For wet basis systems you may use alterna
17. ervice If major components are replaced the interference gas check must be repeated befor returning the analyzer to service The tester must ensure that any specific technology equipment or procedures that are intended to remove interferenc ffects are operating properly during testing 8 3 Dilution Type Systems Special Considerations When a dilution type measurement system is used there are thr important considerations that must be taken into account to ensure the quality of the emissions data First the critical orifice size and dilution ratio must be selected properly so that the sample dew point will be below the sample line and analyzer temperatures Second a high quality accurate probe controller must be used to maintain the dilution ratio during the test The probe controller should be capable of monitoring the dilution air pressure eductor vacuum and sample flow rates Third differences between the molecular weight of calibration gas mixtures and the stack gas molecular weight must be addressed because these can affect the dilution ratio and introduce measurement bias 8 4 Sample Collection 1 Position the probe at the first sampling point Purge the system for at least two times the response time befor recording any data Then traverse all required sampling points sampling at each point for an equal length of time and main
18. f Method 7E may be required by specific New Source Performance Standards Clean Air Marketing rules State Implementation Plans and permits where measurement of NOx concentrations in stationary source emissions is required either to determine compliance with an applicable emissions standard or to conduct performance testing of a continuous monitoring system CEMS Other regulations may also require the use of Method 7E 1 3 Data Quality Objectives DQO How good must my collected data be Method 7E is designed to provide high quality data for determining compliance with Federal and State emission standards and for relative accuracy testing of CEMS In these and other applications the principal objective is to ensure the accuracy of the data at the actual emission levels encountered To meet this objective the use of EPA traceability protocol calibration gases and measurement system performance tests are required 1 4 Data Quality Assessment for Low Emitters Is performance relief granted when testing low emission units Yes For low emitting sources there are alternative performance specifications for analyzer calibration error system bias drift and response time Also the alternative dynamic spiking procedure in Section 16 may provide performance relief for certain low emitting units 2 0 Summary of Method In this method a sample of the effluent gas is continuously sa
19. he NO2 to NO conversion efficiency calculated according to Equation 7E 7 must be greater than or equal to 90 percent The alternative conversion efficiency check described in Section 16 2 2 and calculated according to Equation 7E 9 must not result in a decrease from NOxpear by more than 2 0 percent 13 6 Alternative Dynamic Spike Procedure Recoveries of both pre test spikes and post test spikes must be within 100 10 percent If the absolute difference between th calculated spike value and measured spike value is equal to or less than 0 20 ppmv then the requirements of the ADSC are met 14 0 Pollution Prevention Reserved 15 0 Waste Management Reserved 16 0 Alternative Procedures 16 1 Dynamic Spike Procedure Except for applications under part 75 of this chapter you may use a dynamic spiking procedure to validate your test data for a specific test matrix in place of the interference check and pre and post run system bias checks For part 75 applications use of this procedure is subject to the approval of the Administrator Best results are obtained for this procedure when source emissions are steady and not varying Fluctuating emissions may render this alternative procedure difficult to pass To use this alternative you must meet the following requirements 16 1 1 Procedure Documentation You must detail the procedure you followed in the test report including how the spike was mea
20. ibration error test may be used to m tem calibration error requirement test sequence Also the post run bias or 2 point on error check data may be used as the pre run the next run in the test sequence at the point sys run ina calibrati data for discretion of the tester the pre run 2 for the first 8 6 Alternative Interference and System Bias Checks Dynamic Spike Procedure If I want to use the dynamic spike procedure to validate my data what procedure should I follow Except for applications under part 75 of this chapter you may use the dynamic spiking procedure and requirements provided in Section 16 1 during each test as an alternative to the interference check and the pre and post run system bias checks The calibration error test is still required under this option Use of the dynamic spiking procedure for Part 75 applications is subject to the approval of the Administrator 8 7 Moisture correction You must determine the moisture content of the flue gas and correct the measured gas concentrations to a dry basis using Method 4 or other appropriate methods subject to the approval of the Administrator when the moisture basis wet or dry of the measurements made with this method is different from the moisture basis of either 1 the applicable emissions limit or 2 the CEMS being evaluated for relative accuracy Moisture correction is also required if the appl
21. icable limit is in lb mmBtu and the moisture basis of the Method 7E NOx analyzer is different from the moisture basis of the Method 3A diluent gas COz0r Oz analyzer 9 0 Quality Control What quality control measures must I take The following table is a summary of the mandatory suggested and alternative quality assurance and quality control measures and the associated frequency and acceptance criteria All of the QC data along with the sample run data must be documented and included in the test report Summary Table of QA QC Process or QA OC Acceptance Checking element specification criteria frequency Identify Data User Regulatory Agency or other primary end user of data Analyzer resolution or sensitivity Interference gas check of responses lt 0 5 ppmv for calibration spans of 5 to 10 ppmv lt 0 2 ppmv for calibration spans lt 5 ppmv of certified Before or test gas after each concentration test Calibration on ili Valid certificate required Uncertainty 2 0 of tag value 40 to 60 ee calibration span lt 20 of Each test calibration span anufacturer design Extraction Probe filter and For dry basis Each run sample line analyzers temperature sample above the dew point by j prior to conditioning For wet basis analyzers z n n z z z n n tp ct w ct e an Analyzer amp Calibration Gas Performa
22. ilar to Table 7E 2 1 Next introduce the low level gas in system calibration mode and record the time required for the concentration response to decrease to a value that is within 5 0 percent or 0 5 ppm whichever is less restrictive of the certified low range gas concentration If the low level gas is a zero gas use the procedures described above and observe the change in concentration until the response is 0 5 ppm or 5 0 percent of the upscale gas concentration whichever is less restrictive 2 Continue to observe the low level gas reading until it has reached a final stable value and record the result on a form similar to Table 7E 2 Operate the measurement system at the normal sampling rate during all system bias checks Make only the adjustments necessary to achieve proper calibration gas flow rates at the analyzer 3 From these data calculate the measurement system response time s Section 8 2 6 and then calculate the initial system bias using Equation 7E 2 in Section 12 3 For dilution systems calculate the system calibration error in lieu of system bias using equation 7E 3 in Section 12 4 See Section 13 2 for acceptable performance criteria for system bias and system calibration error If the initial system bias or system calibration error specification is not met take corrective action Then you must repeat the applicable calibration error test from Secti
23. ion gas with a concentration that is less than 20 percent of the calibration span and may be a zero gas 3 3 2 Mid Level Gas means a calibration gas with a concentration that is 40 to 60 percent of the calibration span 3 3 3 High Level Gas means a calibration gas with a concentration that is equal to the calibration span S24 Calibration Span means the upper limit of the analyzer s calibration that is set by the choice of high level calibration gas No valid run average concentration may exceed the calibration span To the extent practicable the measured emissions should be between 20 to 100 percent of the selected calibration span This may not be practicable in some cases of low concentration measurements or testing for compliance with an emission limit when emissions are substantially less than the limit In such cases calibration spans that are practicable to achieving the data quality objectives without being excessively high should be chosen 3 5 Centroidal Area means the central area of the stack or duct that is no greater than 1 percent of the stack or duct cross section This area has the same geometric shape as the stack or duct 3 6 Converter Efficiency Gas means a calibration gas with a known NO or NOgconcentration and of Traceability Protocol quality 3 7 Data Recorder means the equipment that permanently records the concentrations reported by the anal
24. lculate the system calibration error for dilution systems Equation 7E 3 applies to both the initial 3 point system calibration error test and the subsequent 2 point calibration error checks between test runs In this equation the term Cs refers to the diluted calibration gas concentration measured by the analyzer c x DF C SCE 100 Eq 7E 3 ce 12 5 Drift Assessment Use Equation 7E 4 to separately calculate the low level and upscale drift over each test run For dilution systems replace SBrinai and SBi with SCEfinal and SCE respectively to calculate and evaluate drift D B 4 5B Eq 7E 4 fod 12 6 Effluent Gas Concentration For each test run calculate Cayg the arithmetic average of all valid NOx concentration values e g 1l minute averages Then adjust the value of Cay for bias using Equation 7E 5a if you use a non zero gas as your low level calibration gas or Equation 7E 5b if you use a zero gas as your low level calibration gas Case Cae Cay a Eq7E 3a di a Ca Cae Cie Eq 7E 3b Ca T Co 12 7 NO NO Conversion Efficiency If the NOx converter efficiency test described in Section 8 2 4 1 is performed calculate the efficiency using Equation 7E 7 om x100 Eq TE 7 Efan 5 cam 12 8 NO NO Conversion Efficiency Correction If desired calculate the total NOx concentration with a c
25. m calibration mode or both depending upon the type of system used In system calibration mode the system should be able to flood the sampling probe and vent excess gas Alternatively calibration gases may be introduced at the calibration valve following the probe Maintain a constant pressure in the gas manifold For in stack dilution type systems a gas dilution subsystem is required to transport large volumes of purified air to the sample probe and a probe controller is needed to maintain the proper dilution ratio 6 2 7 Sample Gas Manifold Figure 7E 1 the sample gas the sample to the analyzer by pass discharge vent The introduce calibration gases For the type of system shown in manifold diverts a portion of delivering the remainder to the manifold should also be able to directly to the analyzer except for dilution type systems The manifold must be made of material that is non reactive to the gas sampled or the bypass gas the calibration gas and be configured to safely discharge 6 2 8 NO X Analyzer An instrument that continuously measures NOx in the gas stream and meets the applicable specifications in Section 13 0 An analyzer that operates on the principle of chemiluminescence with an NO2 to NO converter is one example of an analyzer that has been used successfully in the past Analyzers operating on other principles may also be used provided the performance
26. may be used to correct the test results for converter efficiency if the NOosfraction in the measured test gas is known Use Equation 7E 8 in Section 12 8 for this correction 8 2 4 1 Introduce NOzsconverter efficiency gas to the analyzer in direct calibration mode and record the NOxconcentration displayed by the analyzer Calculate the converter efficiency Using Equation 7E 7 in Section 12 7 The specification for converter efficiency in Section 13 5 must be met The user is cautioned that state of the art NO2calibration gases may have limited shelf lives and this could affect the ability to pass the 90 percent conversion efficiency requirement 8 2 4 2 Alternatively either of the procedures for determining conversion efficiency using NO in Section 16 2 may be used 8 2 5 Initial System Bias and System Calibration Error Checks Before sampling begins determine whether the high level or mid level calibration gas best approximates the emissions and use it as the upscale gas Introduce the upscale gas at the probe upstream of all sample conditioning components in system calibration mode Record the time it takes for the measured concentration to increase to a value that is within 95 percent or 0 5 ppm whichever is less restrictive of the certified gas concentration Continue to observe the gas concentration reading until it has reached a final stable value Record this value on a form sim
27. mpled and conveyed to the analyzer for measuring the concentration of NOx You may measure NO and NOzseparately or simultaneously together but for the purposes of this method NOx is the sum of NO and NO2 You must meet the performance requirements of this method to validate your data 3 0 Definitions 3 1 Analyzer Calibration Error for non dilution systems means the difference between the manufacturer certified concentration of a calibration gas and the measured concentration of the same gas when it is introduced into the analyzer in direct calibration mode 3 2 Calibration Curve means the relationship between an analyzer s response to the injection of a series of calibration gases and the actual concentrations of those gases 3 3 Calibration Gas means the gas mixture containing NOxat a known concentration and produced and certified in accordance with EPA Traceability Protocol for Assay and Certification of Gaseous Calibration Standards September 1997 as amended August 25 1999 EPA 600 R 97 121 or more recent updates The tests for analyzer calibration error drift and system bias require the use of calibration gas prepared according to this protocol If a zero gas is used for the low level gas it must meet the requirements under the definition for zero air material in 40 CFR 72 2 in place of being prepared by the traceability protocol 3 3 1 Low Level Gas means a calibrat
28. nce System Performance System Performanc anifolding material Equipment efficiency Analyzer calibration error or 3 point system calibration error for dilution systems or System bias pre and post run 2 point system calibration error for dilution systems System Performance System Performance System respons time NO2 NO conversion Verified through system bias check lt 5 target compound removal Within 2 0 of the calibration Before initial run and after a failed system bias test or dilution drift calibration gases Itest Alternative specification ppmv absolute difference 0 55 for low scale and upscale calibration gases Alternative specification ppmv absolute difference 0 5 Determines minimum sampling time per point During initial sampling system bias 3 0 of calibration span for low level and mid or high level gases Alternative specification ppmv absolute difference 0 5 n ll ES D 10 0 Suggested Mandatory Alternative System Performance System Performance Sample Point Selection Multiple sample points simultaneously Data Parameters Data Parameters System Performance Purge time Minimum sample time at each point Stable sample flow rate surrogate for maintaining system response time Stratification test No of openings in probe Sample concentration range Average
29. not make adjustments for any other purpose For dilution systems you must operate the measurement system at the appropriate dilution ratio during all system calibration error checks and may make only the adjustments necessary to maintain the proper ratio 2 Record the analyzer s response to each calibration gas on a form similar to Table 7E 1 For each calibration gas calculate the analyzer calibration error using Equation 7E 1 in Section 12 2 or the system calibration error using Equation 7E 3 in Section 12 4 as applicable The calibration error specification in Section 13 1 must be met for the low mid and high level gases If the calibration error specification is not met take corrective action and repeat the test until an acceptable 3 point calibration is achieved 8 2 4 NO 2 to NO Conversion Efficiency Test Before or after each field test you must conduct an NO2to NO conversion efficiency test if your system converts NO2to NO before analyzing for NOx You may risk testing multiple facilities before performing this test provided you pass this test at the conclusion of the final facility test A failed final conversion efficiency test in this case will invalidate all tests performed subsequent to the test in which the converter efficiency test was passed Follow the procedures in Section 8 2 4 or 8 2 4 2 If desired the converter efficiency factor derived from this test
30. ntration indicated by data recorder for the test run ppmv Pollutant concentration adjusted to dry conditions ppmv Measured concentration of a calibration gas low mid or high when introduced in direct calibration mode ppmv Averag ffluent gas concentration adjusted for bias ppmv Average of initial and final system calibration bias or 2 point system calibration error check responses for the upscale calibration gas ppmv Actual concentration of the upscale calibration gas ppmv NOx concentration in the stack gas as calculated in Section 12 6 ppmv Average of the initial and final system calibration bias or 2 point system calibration error check responses from the low level or zero calibration gas ppmv Actual concentration of the low level calibration gas ppmv Measured concentration of a calibration gas low mid or high when introduced in system calibration mode ppmv Concentration of NOx measured in the spiked sample ppmv Concentration of NOxin the undiluted spike gas ppmv Calculated concentration of NOxin the spike gas diluted in the sample ppmv Cy Cw CS DF Ef fno2 NOxcorr NOxFinal NOxpeak Qspike Qrotal SB SBi SBfinal SCE SCEi Manufacturer certified concentration of a calibration gas low mid or high ppmv Pollutant concentration measured under moist sample conditions wet basis ppm
31. on 8 2 3 and the initial system bias or 2 point system calibration error check until acceptable results are achieved after which you may begin sampling Note For dilution type systems data from the 3 point system calibration error test described in Section 8 2 3 may be used to meet the initial 2 point system calibration error test requirement of this section if the calibration gases were injected as described in this section and if response time data were recorded 8 2 6 Measurement System Response Time As described in section 8 2 5 you must determine the measurement system response time during the initial system bias or 2 point system calibration error check Observe the times required to achieve 95 percent of a stable response for both the low level and upscale gases The longer interval is the response time 8 2 7 Interference Check Conduct an interference response test of the gas analyzer prior to its initial use in the field If you have multiple analyzers of the same make and model you need only perform this alternative interference check on one analyzer You may also meet the interferenc check requirement if the instrument manufacturer performs this or similar check on the same make and model of analyzer that you use and provides you with documented results 1 You may introduce the appropriate
32. on as the average stack concentration Cag for the first spike level or if desired for both pre test spike levels Introduce the first level spike gas into the system in system calibration mode and begin sample collection Wait for at least two times the system response time before measuring the spiked sample concentration Then record at least five successive l minute averages of the spiked sample gas Monitor the spike gas flow rate and maintain at the determined addition rate Average the fiv l minute averages and determine the spike recovery using Equation 7E 12 Repeat this procedure for the other pre test spike level The recovery at each level must be within the limits in Section 13 6 before proceeding with the test 2 Conduct the number of runs required for the test Then repeat the above procedure for the post test spike evaluation The last run of the test may serve as the average stack concentration for the post test spike test calculations The results of the post test spikes must meet the limits in Section 13 6 16 2 Alternative NO 2 to NO Conversion Efficiency Procedures You may use either of the following procedures to determine converter efficiency in place of the procedure in Section 8 2 4 1 16 2 1 The procedure for determining conversion efficiency using NO in 40 CFR 86 123 78 16 2 2 Tedlar Bag Procedure Perform the analyzer calibra
33. only one pollutant or diluent this requirement A stratification test is not required for small stacks that are less stratification to measure the NOxy or pollutant of traverse points located twelve measure at area traverse point traverse point t of the measurement th If testing sit a sam A than 4 inches in use a probe of of Method 1 three points on a line the thr points line time s Calculate the If the differs from the mean s by no more than a Spac e the mean concentrat r is less rest r 0 5 ppm crit concentra tion at each trictive tion or b 0 5 ppm the gas stream is tified and you may collec tches the samples froma mean If the 5 0 terion is not traverse point concentra 10 0 percent of the mean less rest minimally s Space points tion for all rictive the tratified met but the t differs from the mean traverse point 1 0 ppm or b ts by no more than a whichever is gas stream is considered to be percent o f the three points at the measurement line A and you may take samples from three PGs lternatively and 83 3 if a twelve 50 0 point stratification test was performed and the emissions shown EO be percent o S S th tack diameter tack or duct yo
34. orrection for converter efficiency using Equation 7E 8 HO HO HO a NO x100 Eg 7E B Eff LZ 9 Alternative NO 2 Converter Efficiency If the alternative procedure of Section 16 2 2 is used determin the NOx concentration decrease from NOxpea x after the minimum 30 minute test interval using Equation 7E 9 This decrease from NOxypeax must meet the requirement in Section 13 5 for the converter to be acceptable NG eran NO rat y 100 Eq 7E 9 No AP ht 90 Decrease 12 10 Moisture Correction Use Equation 7E 10 if your measurements need to be corrected to a dry basis Cw 4B Eq TE 10 pg 12 11 Calculated Spike Gas Concentration and Spike Recovery for the Example Alternative Dynamic Spiking Procedure in Section 16 1 3 Use Equation 7E 11 to determine the calculated spike gas concentration Use Equation 7E 12 to calculate the spike recovery Cx Os ite Calc Q ori Eq 7E 11 DF ee E Cas Hi C piste C pte R x100 Eq TE 12 13 0 Method Performance 13 1 Calibration Error This specification is applicable to both the analyzer calibration error and the 3 point system calibration error tests described in Section 8 2 3 At each calibration gas level low mid and high the calibration error must either be within 2 0 percent of the calibration span Alternatively the results are acceptable if Cair on or cs Cy as applicable is lt 0 5 ppmv
35. rated with both NO and NO2 2 You must include a copy of the manufacturer s certification of the calibration gases used in the testing as part of the test report This certification must include the 13 documentation requirements in the EPA Traceability Protocol For Assay and Certification of Gaseous Calibration Standards September 1997 as amended August 25 1999 When Method 205 is used to produce diluted calibration gases you must document that the specifications for the gas dilution system are met for the test You must also include the date of the most recent dilution system calibration against flow standards and the name of the person or manufacturer who carried out the calibration in the test report 11 0 Analytical Procedures Because sample collection and analysis are performed together s Section 8 additional discussion of the analytical procedure is not necessary 12 0 Calculations and Data Analysis You must follow the procedures for calculations and data analysis listed in this section Zai Nomenclature The terms used in the equations are defined as follows ACE Analyzer calibration error percent of calibration span Bus Cavg Cp Cpir Ceas Cm Cuma Cyative Co Coa Cs Cspike Ccalc Moisture content of sample gas as measured by Method 4 or other approved method percent 100 Average unadjusted gas conce
36. subjecting it to the tests listed in Table 7E 5 following procedures similar to those in 40 CFR 53 23 for thermal stability and insensitivity to supply voltage variations If the analyzer will be used under temperature conditions that are outside the test conditions in Table B 4 of Part 53 23 alternative test temperatures that better reflect the analyzer field environment should be used Alternative procedures or documentation that establish the analyzer s stability over the appropriate line voltages and temperatures are acceptable 17 0 References 1 EPA Traceability Protocol for Assay and Certification of Gaseous Calibration Standards September 1997 as amended EPA 600 R 97 121 18 0 Tables Diagrams Flowcharts and Validation Data Figure 7E 1 Measurement System Sample By Pass Vent View or download PDF Figure 7E 2 Testing Flow Chart Calibration Gas Verification m e Analyzer z or 3 point System Calibration Error Initial System Bias Check or 2 point System Calibration Error Pass Post run System Bias Check or 2 point System Calibration Error For ditution type systems View or download PDF 2 Continue until test is completed Table 7E 1 Analyzer or System Calibration Error Data Source Identification Test personnel Date Time Low level or zero calibration g
37. sured added verified during the run and calculated after the test 16 1 2 Spiking Procedure Requirements The spikes must be prepared from EPA Traceability Protocol gases Your procedure must be designed to spike field samples at two target levels both before and after the test Your target spike levels should bracket the average sample NOx concentrations The higher target concentration must be less than the calibration span You must collect at least 5 data points for each target concentration The spiking procedure must be performed before the first run and repeated after the last run of the test program 16 1 3 Example Spiking Procedure Determine the NO concentration needed to generate concentrations that are 50 and 150 percent of the anticipated NOx concentration in the stack at the total sampling flow rate while keeping the spike flow rate at or below 10 percent of this total Use a mass flow meter accurate within 2 0 percent to generate these NO spike gas concentrations at a constant flow rate Use Equation 7E 11 in Section 12 11 to determine th calculated spike concentration in the collected sample 1 Prepare the measurement system and conduct the analyzer calibration error test as described in Sections 8 2 2 and 8 2 3 Following the sampling procedures in Section 8 1 determine the stack NOx concentration and use this concentrati
38. taining the appropriate sample flow rate or dilution ratio as applicable You must record at least one valid data point per minute during the test run 2 Each time the probe is removed from the stack and replaced you must recondition the sampling system for at least two times the system response time prior to your next recording If the average of any run exceeds the calibration span value that run is invalid 3 You may satisfy the multipoint traverse requirement by sampling sequentially using a single hole probe or a multi hole probe designed to sample at the prescribed points with a flow within 10 percent of mean flow rate Notwithst chapter approval anding for applications under part 75 of this the use of multi hole probes is subject to the of the Administrator 8 5 Post Run System Bias Check and Drift Assessment How do I each run calibrati the run confirm that each sampl e I collect is valid After repeat the system bias check or 2 point system on error check for dilution systems to validate Do not make adjustments other than to maintain dilution completion of the post run system on error check Note tha calibrati bias or 2 inject the low level gas first and vice vers performing the post run bias or syst check provided you pass this group of invalidat to the measurement system
39. tion error test to document the calibration both NO and NOx modes as applicable Fill a Tedlar bag approximately half full with either ambient air pure oxygen or an oxygen standard gas with at least 19 5 percent by volume oxygen content Fill the remainder of the bag with mid to high level NO in nitrogen or other appropriate concentration calibration gas Note that the concentration of the NO standard should be sufficiently high that the diluted concentration will be easily and accurately measured on the scale used The size of the bag should be large enough to accommodate the procedure and time required 1 Immediately attach the bag to the inlet of the NOx analyzer or external converter if used In the case of a dilution system introduce the gas at a point upstream of the dilution assembly Measure the NOx for a period of 30 minutes If the NOx concentration drops more than 2 percent absolute from the peak value observed then the NOsconverter has failed to meet the criteria of this test Take corrective action The highest NOx value observed is considered to be NOxpeax The final NOx value observed is considered to be NOx inai 2 Reserved 16 3 Manufacturer s Stability Test A manufacturer s stability test is required for all analyzers that routinely measure emissions below 20 ppmv and is optional but recommended for other analyzers This test evaluates each analyzer model by
40. tive equipment and supplies as needed some of which are described in Section 6 2 provided that the measurement system meets the applicable performance specifications of this method 6 2 Measurement System Components 6 2 1 Sample Probe Glass stainless steel or other approved material of sufficient length to traverse the sample points 6 2 2 Particulate Filter An in stack or out of stack filter The filter must be made of material that is non reactive to the gas being sampled The filter media for out of stack filters must be included in the system bias test The particulate filter requirement may be waived in applications where no significant particulate matter is expected e g for emission testing of a combustion turbine firing natural gas 6 2 3 Sample Line The sample line from the probe to the conditioning system sample pump should be made other material that does not absorb or otherwis of Teflon or alter th sample gas For a dry basis measurement system as shown in Figure 7E 1 the temperature of the sample line must be maintained at a sufficiently high level to prevent condensation before the sample conditioning components For wet basis measurement systems the temperature sample line must be maintained at a sufficient of the y high level to prevent condensation before the analyzer 6 2 4 Conditioning Equipment For dry basis
41. u may use 3 point sampling and loca f along minimally stratified their mean or within or equivalent diameter is greater than 2 4 meters all points within 1 0 ppm 10 0 and if the for a rectangular 7 8 ft then three points th Le measurement line exhibiting the highest average concen and 2 tration during O meters from the st tratification the stack or duct wall test TE stream is found to be strat or twe Tab tified becaus th 0 4 he gas a ale 10 0 percent 1 0 ppm criterion for a 3 point test is not met lve traverse points for the test in accordance with le 1 1 or Table 1 2 of Method 1 0 locate 8 2 Initial Measurement System Performance Tests What initial performance criteria must my system meet before I begin collecting samples Before measuring emissions perform the following procedures a Calibration gas verification b Measurement system preparation c Calibration error test d NOzto NO conversion efficiency test if applicable e System bias check f System response time test and g Interference check 8 2 1 Calibration Gas Verification How must I verify the concentrations of my calibration gases Obtain a certificate from the gas manufacturer documenting the quality of the gas Confirm that the manufacturer certification is complete and current Ensure that your
42. v Calibration span ppmv Drift assessment percent of calibration span Dilution system dilution factor or spike gas dilution factor dimensionless NO2to NO converter efficiency percent The NOx concentration corrected for the converter efficiency ppmv The final NOx concentration observed during the converter efficiency test in Section 16 2 2 ppmv The highest NOx concentration observed during the converter efficiency test in Section 16 2 2 ppmv Flow rate of spike gas introduced in system calibration mode L min Total sample flow rate during the spike test L min Spike recovery percent System bias percent of calibration span Pre run system bias percent of calibration span Post run system bias percent of calibration span System calibration error percent of calibration span Pre run system calibration error percent of calibration span SCErinal Post run system calibration error percent of calibration span 12 2 Analyzer Calibration Error For non dilution systems use Equation 7E 1 to calculate the analyzer calibration error for the low mid and high level calibration gases ACE Sn Cv x 199 Eq 7E 1 cs 12 3 System Bias For non dilution systems use Equation 7E 2 to calculate the system bias separately for the low level and upscale calibration gases gp fe One x100 Eq 7E 2 cs 12 4 System Calibration Error Use Equation 7E 3 to ca
43. yzer 3 8 Direct Calibration Mode means introducing the calibration gases directly into the analyzer or into the assembled measurement system at a point downstream of all sample conditioning equipment according to manufacturer s recommended calibration procedure This mode of calibration applies to non dilution type measurement systems 3 9 Drift means the difference between the pre and post run system bias or system calibration error checks at a specific calibration gas concentration level i e low mid or high 3 10 Gas Analyzer means the equipment being measured and generates an output concentration that senses the gas proportional to its 3 11 Interference Check means the test to detect analyzer responses to compounds other than the compound of interest usually a gas present in the measured gas stream that is not adequately accounted for in the calibration procedure and may cause measurement bias 3 12 Low Concentration Analyzer means any analyzer that operates with a calibration span of 20 ppm NOx or lower Each analyzer model used routinely to measure low NOx concentrations must pass a Manufacturer s Stability Test MST An MST subjects the analyzer to a range of line voltages and temperatures that reflect potential field conditions to demonstrate its stability following procedures similar to those provided in 40 CFR 53 23 Ambient level analyzers are exempt from
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