                            DRAFT VERSION 9-19-2012
                                       
                      DRAFT PERFORMANCE SPECIFICATION 18
PERFORMANCE SPECIFICATIONS AND TEST PROCEDURES FOR HCl CONTINUOUS EMISSION MONITORING SYSTEMS IN STATIONARY SOURCES

1.0 Scope and Application.
      
        1.1 Analyte. This performance specification is applicable for measuring gaseous concentrations of HCl (CAS: 7647-01-0) on a continuous basis in the units of the applicable standard or in units that can be converted to units of the applicable standard(s). 

        1.2 Applicability. 

            1.2.1 This specification is for evaluating the acceptability of Hydrogen Chloride (HCl) continuous emission monitoring systems (CEMS) at the time of installation or soon after and whenever specified in the regulations. The specification includes requirements for initial acceptance including (1) instrument accuracy and (2) stability assessments.

            1.2.2  This specification is not designed to evaluate the ongoing CEMS performance nor does it identify specific calibration techniques and auxiliary procedures to assess CEM performance over an extended period of time. The source owner or operator is responsible to calibrate, maintain, and operate the CEMS properly. The Administrator may require the operator under Section 114 of the Act, to conduct CEMS performance evaluations at other times besides the initial test to evaluate the CEMS performance. See 40 CFR Part 60, §60.13(c) and §63.8(e)(1).  

            1.2.3 A source that demonstrates their continuous emission monitoring system (CEMS) meets the criteria of this performance specification may use the system to continuously monitor gaseous hydrogen chloride (HCl). If your HCl CEMS is capable of reporting the HCl concentration in the units of the existing standard, no additional CEMS components are necessary. If your HCl CEMS does not report concentrations in the units of the existing standard, then other CEMS components (e.g., oxygen, temperature, stack gas flow, and pressure) are necessary to convert the units reported by your HCl CEMS to the units of the standard. 

            1.2.4 This specification test results are intended to be valid for the life of the system. As a result, the HCl measurement system must be tested and operated in a configuration consistent with the configuration that will be used for continuous emissions monitoring. Substantive changes to the system configuration require retesting according to this performance specification. Examples of such conditions include, but are not limited to: major changes in dilution ratio (for dilution based systems), changes in catalyst materials, changes in filtering device design or materials, changes in probe design or configuration, and changes in gas conditioning materials or approaches.


2.0 Summary of Performance Specification.

        2.1 This specification covers the procedures that each HCl CEMS must meet during the performance evaluation test. CEM installation and measurement location specifications, data reduction procedures and performance criteria are included. You must complete the following tests to meet the requirements of this Performance Specification.

            a. Interference Test; 
            b. Limit of Detection (LOD) Determination; 
            c. Response Time Test;
            d. Calibration Error Test;
            e. Calibration Drift Test; 
            f. Stratification Test and
            g. Relative Accuracy Test or Dynamic Spiking Test

        2.2 The technology used to measure gaseous HCl must provide a distinct response and address any appropriate interference correction(s). It must accurately measure gaseous HCl in a representative sample (path or point sampling) of stack effluent.

        2.3 Relative accuracy (RA) may be established either against a reference method (e.g., Method 26A, Method 320, ASTM D6348-12 including mandatory annexes, or Method 321, as appropriate for the source concentration and category) or by dynamic spiking a secondary source of EPA Protocol HCl or NIST traceable standard into the CEMS.

3.0 Definitions.

            3.1 Calibration Cell is a gas containment cell that remains in the optical measurement path of the cross stack or integrated path monitors to perform precision and bias checks. The cell can be evacuated and/or purged to remove calibration gas and substitute zero gas. When charged it contains a known concentration of HCl calibration gas.  The calibration cell is filled with zero gas or evacuated during stack gas measurement.

            3.2 Calibration Curve means the relationship between an analyzer's response to the addition of a series of calibration gases and the actual concentrations of those gases.

            3.3 Calibration Drift (CD) is the absolute value of the difference between the CEMS output response and an upscale reference gas or a zero-level reference gas, expressed as a percentage of the span value, when the CEMS is challenged after a stated period of operation during which no unscheduled maintenance or repair took place.  A separate CD determination must be performed for the pollutant and diluent analyzers.

            3.4 Calibration Error (CE) is the mean difference between the concentration measured by the CEMS and the known concentration from a calibration source, divided by the span, when the entire CEMS, including the sampling interface is challenged. 

            3.5 Calibration Span is the upper limit of valid instrument response during sampling. To the extent practicable the measured emissions are to be between 10 and 100 percent of the selected calibration span. The calibration span must accommodate the dynamic spiking procedure if that option is selected to determine relative accuracy. Span may be specified for the affected source category in an applicable subpart of the regulations.

            3.6 Centroidal Area means a central 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.

            3.7 Continuous Emission Monitoring System (CEMS) means all of the total equipment required to measure the pollutant concentration or emission rate as a continuous operation. 

            3.8 Continuous Operation is the time between periodic maintenance when an instrument and sampling system operates without user intervention, continuously samples flue gas, records measurement data, analyzes the data for HCl, and saves the results to a computer file. User intervention is permitted for initial set-up of sampling system, initial calibrations, and periodic maintenance.

            3.9 Data Recorder is the portion of the CEMS that provides a permanent record of analyzer output. The data recorder may record other pertinent data such as effluent flow rates, various instrument temperatures or abnormal CEMS operation.  The data recorder may also include automatic data reduction capabilities and CEMS control capabilities.

            3.10 Diluent Analyzer means that portion of the CEMS that senses the diluent gas (e.g., O2) and generates an output proportional to the gas concentration.

            3.11 Dynamic Spiking is the procedure where a known concentration of HCl gas is injected into the probe sample gas stream for extractive CEMS at a known flow rate, or spiked into a calibration cell for in-situ integrated path CEMS in order to assess the accuracy of the measurement system in the presence of the flue gas sample matrix.


            3.12 Independent Measurement(s) means one minute averages of CEMS data taken during sample gas analysis separated by a complete flush of the extractive measurement system or in-situ CEMS optical path. 

            3.13 Interference is a compound or material in the sample matrix other than HCl whose characteristics may bias the instrument signal (positively or negatively) once the HCl enters the CEMS. The interference may not prevent the sample measurement, but could increase the analytical uncertainty in the measured concentration through reaction with HCl or by changing the electronic signal generated during HCl measurement.

            3.14 Interference Test means the test to detect analyzer responses to compounds other than HCl, usually gases present in the measured gas stream, that are not adequately accounted for in the calibration procedure and may cause measurement bias.
      
            3.15 Integrated Path Sampling CEMS (IPS-CEMS) is a CEMS that measure the gas concentration along a path greater than 10 percent of the equivalent diameter of the stack or duct cross section.

            3.16 Limit of Detection (LOD) is the lowest level of pollutant the CEMS can detect with 99% confidence in the presence of typical interferents.

            3.17 Liquid Evaporative Calibration Material is produced by an evaporative HCl generator using liquid standards of known concentration by vaporizing aqueous solutions of HCl and quantitative mixing the resultant vapor with a diluent carrier gas.
      
            3.18 Optical Path is the route light travels from a light source to the receiver during an optical CEMS sample measurement. 

            3.19 Path Length for extractive optical CEMS is the distance in meters of the optical path within the gas measurement cell. For cross stack IPS-CEMS path length is the distance in meters of the optical path that passes through the sample gas.

            3.20 Point CEMS is a CEMS that measures the source gas concentration either at a single point or over a path less than 10 percent of the equivalent diameter of the stack or duct cross section.

            3.21 Pollutant Analyzer means that portion of the CEMS that senses, quantifies and generates an output proportional to the stack gas HCl concentration. 

            3.22 Protocol Gas Standard is an EPA protocol compressed gas standard with known concentration certified by the supplier to meet the requirements of EPA protocol gases.

            3.23 Reference Gas Value (R) is the certified or recertified concentration of a gas standard.  Note:  For in-situ integrated path (IP) CEMS, the reference value will be calculated as the equivalent concentration corresponding to the stack measurement path length, temperature and pressure. 

            3.24 Relative Accuracy is the absolute mean difference determined by the CEMS between either a) the reference method (RM) plus the 95 percent confidence coefficient divided by the average RM value or the applicable emission standard or b) the measured gas concentration dynamically spiked into the sampling system and the traceable concentration of the dynamically spiked gas divided by the traceable spiked gas concentration. 
      
            3.25 Response Time (RT) is the time it takes for the measurement system, while operating normally at its target sample flow rate, dilution ratio, or data collection rate to respond to a known step change in gas concentration from a low or zero level to a high-level gas and to read within five percent of the stable high-level gas response. 

            3.26 Sample Interface is the portion of the CEMS used for one or more of the following: sample acquisition, sample transport, sample conditioning, or protection of the analyzer from the effects of stack gas.

            3.27 Span Value means a conservatively high estimate of the range of HCl measurements expected as defined in the applicable regulation or other requirement.  The span value defines the calibration and quality assurance HCl concentrations. If the span is not defined in the applicable regulation or other requirement then it must be a value approximately equivalent to two times the emission standard.  
      
            3.28 Stratification means the difference in effluent concentration in a duct, when comparing a reference measurement at the centroid of the duct to traversed measurements.

            3.29 Zero Standard means a calibration gas or gaseous liquid spike with an HCl concentration that is below the LOD of the measurement system.
      
4.0 Interferences. Interferences will vary among instruments and potential instrument-specific matrix interferences.  Interferences must be evaluated through the interference test in this performance specification. Several compounds, including water, carbon monoxide, carbon dioxide, formaldehyde and methane are potential interferences with certain types of HCl monitoring technology. 

5.0 Safety. The procedures required under this performance specification may involve hazardous materials, operations, and equipment. This performance specification may not address all of the safety problems associated with these procedures. The user is responsible to establish appropriate safety and health practices and determine the applicable regulatory limitations prior to performing these procedures. The CEMS users should consult instrument operation manuals, compressed gas safety requirements such as Occupational Safety and Health Administration (OSHA) regulations and other material safety data sheets for specific precautions to be taken.

6.0 Equipment and Supplies. Equipment and supplies for HCl CEMS will vary depending on the measurement technology and equipment vendors. This section provides a description of the equipment and supplies typically found in one or more types of HCl CEMS.

       6.1 Sample Extraction System: The portion of an extractive CEMS that collects and transports the sample to the pressure regulation and sample conditioning module. The extraction system must deliver a representative sample to the measurement instrument. The sample extraction system typically consists of a sample probe and a heated umbilical line.

       6.2 Pressure Regulation and Sample Conditioning Module.
The Pressure regulation and sample conditioning module removes free particulates and moisture, as applicable, from the gas stream prior and provide a sample gas stream to the CEMS analysis module. You must keep the particle free gas sample above the dew point temperature of its components. 

       6.3 HCl Analyzer is the portion of the CEMS that detects, quantifies and generates an output proportional to the stack gas HCl concentration.

       6.4 Diluent analyzer is the portion of the CEMS that quantifies stack gas concentrations of oxygen or carbon dioxide (CO2).  For systems with a multi-component analyzer, the same analyzer may quantify for all measured gases.

       6.5 System Controller is the portion of the CEMS that provides control of the analyzer, sample extraction system including the probe, pressure regulation and sample conditioning module and the sample interface.

       6.6 Data recorder is the portion of the CEMS that provides a record of analyzer output. The data recorder may record other pertinent data such as effluent flow rates, various instrument temperatures or abnormal CEMS operation.  The data recorder output range must include the full range of expected HCl concentration values in the gas stream to be sampled including zero and span value. Multiple instrument ranges or extended calibration points to extend the measurement range may be necessary to measure concentrations encountered during normal process operation. 
 
       6.7 Reference Gas System(s).  One or more systems may be needed to introduce calibration gases into the measurement system.  A reference gas system must be able to introduce a known concentration of HCl gas into the measurement system in the same way that samples are analyzed.  For extractive CEMS, the system must be able to flood the sampling probe sufficiently to prevent entry of gas from the effluent stream.  For integrated path CEMS the system must be able to introduce a known concentration of HCl, at known pressure and temperature into the optical path used to measure sample gas HCl concentration.

       6.8 Moisture Measurement System.  If correction of the measured HCl emissions for moisture is required, either Method 4 in appendix A-3 of this part or other moisture measurement methods approved by the Administrator will be needed to measure stack gas moisture content.
 
            7.0 Reagents and Standards.

          8.1 Reference gases used to meet the performance specifications must meet EPA protocol gas requirements.

          8.2 Traceable gas and/or liquid standards must be used within their certification period.

          8.3 High concentration HCl standards may be diluted and used to measure high-level calibration drift. You must document the quantitative introduction of HCL standards into the system using Method 205 or similar procedure.

          8.4 Reference gas standards may also be required for diluent gas analysis.
            7.0 CEMS Measurement Location Specifications and Pretest Preparation

          8.5 Prior to the start of your initial performance specification tests, you must ensure that the HCl CEMS is installed according to the manufacturer's specifications and the requirements in this Section. You may use either point or integrated path sampling technology.

          8.6 Installation. Install the CEMS at an accessible location downstream of all pollution control equipment.  Place the probe outlet or other sampling interface at a point or location in the stack (or vent) representative of the stack gas concentration of HCl.  

          8.7 Stratification Restrictions. You must select a sampling point that meets the stratification restrictions in this performance specification. If you fail the relative accuracy requirements in this specification due to the measurement location and a satisfactory correction technique cannot be established, the Administrator may require the CEMS to be relocated.  Measurement locations and points or paths that are most likely to provide data that will meet the relative accuracy requirements are described in Sections 8.4 below.

          8.8 Measurement Location.  The measurement location should be (1) at least two equivalent diameters downstream of the nearest control device, point of pollution generation or other point at which a change of pollutant concentration may occur, and (2) at least half an equivalent diameter upstream from the effluent exhaust.  The equivalent duct diameter is calculated according to Method 1 in appendix A-1 to this part.

      0.6.1 Single point sample gas extraction should be (1) no less than 1.0 meter (3.3 ft) from the stack or duct wall or (2) within the centroidal velocity traverse area of the stack or duct cross section. 

      0.6.2 Path integrated measurements must (1) be conducted totally within the inner area bounded by a line 1.0 meter (3.3 ft) from the stack or duct wall, or (2) have at least 70 percent of the path within the inner 50 percent of the stack or duct cross-sectional area, or (3) be located over any part of the centroidal area.

          2.1 CEMS and Data Recorder Scale Check.  After CEMS installation, we recommend you check the calibration error as described in Section 11.4 to verify that the instrument is functioning properly. Record and document the measurement range of the HCl CEMS. The CEMS operating range (zero to span) and the range of the data collection device must encompass all expected HCl concentrations and the applicable emission limit, if practicable. The CEMS and data collection device output range must include zero and the span value.

            7.0 Quality Control. [Reserved] 

 
            8.0 Calibration and Standardization [Reserved]
 

            9.0 Performance Specification Test Procedure. After completing the CEMS installation, setup and calibration you must complete the performance evaluation test procedures in this section. The ultimate evaluation of the CEMS performance and accuracy is accomplished by using a RA test against a reference method or by dynamically spiking reference HCl gas standards through the sampling probe.  You must perform the following procedures to demonstrate initial performance of your HCl CEMS:
Interference Test:

            a. Interference Test
            b. Limit of Detection (LOD) Determination; 
            c. Response Time Test;
            d. Calibration Error Test;
            e. Calibration Drift Test; 
            f. Stratification Test and
            g. Relative Accuracy Test or Dynamic Spiking Test

          7.1 Interference Test

      0.6.3 You must conduct this interference test of your measurement system prior to its initial use in the field to verify that the candidate test instrument is free from inherent biases or interferences resulting from common emission constituents. It may be conducted in either a controlled environment or on site during initial setup and qualification of your CEMS. If you have multiple measurement systems with components of the same make and model numbers, you need only perform this interference check on one system and you may also rely on an interference test conducted by the manufacturer on a system having components of the same make and model(s) of the system that you use.

      0.6.4 Select an appropriate calibration span that reflects the source(s) to be tested and perform the interference check with the HCl concentration equivalent to 20 to 40 percent of the lowest calibration span value anticipated.  Alternatively, successfully conducting the interference test at the relevant regulatory standard may be used to demonstrate performance. 

      0.6.3 Introduce the interference test gases listed in Table 1 in Section 17.0 into the measurement system separately or in any combination.

                              0.6.3.1 For extractive CEMS the interference test gases must be introduced into the sampling system at the probe such that the interference gas mixtures pass through all filters, scrubbers, conditioners, and other components as would be configured for normal sampling.
  
                              0.6.3.2 For in-situ CEMS the interference test gases may be added with the HCl in a permanently installed calibration cell. Test gas concentration, (Cspike), and interference gas concentration is the effective concentration corrected for the nominal stack sampling path length of the CEMS.

      0.6.4 The interference test must be performed using HCl, and each interference test gas (or gas mixture) must be evaluated in triplicate. This is accomplished by measuring the HCl response first with only the HCl gas present and second when adding the interference test gas(es) while maintaining constant HCl concentration. You must assess the combined interference of all of the gases in Table 1. 

      0.6.5 You must document the quality of the gas volume/rate used to conduct the interference test to be able to establish the error of blending the HCl and interference gases while maintaining a known HCl concentration. A gas blending system or manifolds may be used.

      0.6.6 The duration of each test should be for a sufficient period of time to ensure the HCl measurement system surfaces are conditioned and a stable output is obtained. Measure the HCl response of the analyzer to these gases in ppm. Record the responses and determine the overall interference response using Table 2 in Section 17.0. 

      0.6.3 For each interference gas (or mixture), calculate the mean difference between the measurement system responses with and without the interference test gas(es) using Equation 1 in Section 12.  Summarize the results following the format contained in Table 2 in Section 17.

      0.6.4 Calculate the total interference for the gases runs using Equation 2 in Section 12.  The combined interference response for the analyzer that was used for the test must not be greater than 3.0 percent of the calibration span used for the interference test.

          4.1 Limit of Detection (LOD) Determination.
 
      0.6.5 You must determine the minimum amount of HCl that can be detected (LOD) above the background in a representative gas matrix.

      0.6.6 You may perform the LOD determination as part of the interference test in Section 11.1, in either a controlled environment or on site during initial setup and qualification of your CEMS. 

      0.6.7 The challenge standard used to determine LOD must consist of the interferences listed in Table 1 and HCl at a concentration within two to five times the estimated limit of detection.

      0.6.8 For extractive CEMS, spike this mixture into the CEMS at the probe prior to all filters and sample conditioning elements. For integrated path CEMS, spike this mixture into the system calibration cell.  Collect seven (7) independent measurements under these conditions. LOD for integrated path units must be determined and reported on a ppm-meter basis and site or installation specific LOD must be calculated based on the actual measurement path length of the specific site installation. 

      0.6.9 Calculate the standard deviation of the measured values and estimate the LOD as 3 times the standard deviation of these measurements. 

          9.3 Response Time Determination

       6.9.1 Determine the average upscale and downscale response times from three repetitions of each test. You will report the greater of the average upscale or average downscale response times as the response time for the system.

       6.9.2 Determine the upscale response time by injecting zero gas into the measurement system at the extractive probe or integrated path calibration cell inlet. You may use humidified zero gas.

       6.9.3 When the system output has stabilized (no change greater than 1 percent of full scale for 30 sec), introduce an upscale reference gas and take repetitive measurements until you obtain a stable value at 95 percent or greater than the expected calibration gas response. You may use humidified calibration gas.
 
       6.9.4 Record the time (upscale response time) required to reach 95 percent of the final stable value. 

       6.9.5 Next, reintroduce the zero gas and record the time required to reach 5 percent of the upscale gas reading.  This time is the downscale response time. 

Note: For CEMS that perform a series of operations, (purge-blow back, sample integration, analyze, etc.) you must start adding calibration gases immediately after filter blow back procedures are complete to produce the longest response time.

       6.9.6 Repeat the entire procedure three times and determine the mean upscale and downscale response times. The slower or longer of the two means is the system response time.

          6.3 Calibration Error Test.  The percent calibration error is the mean difference between the HCl reference gas value, (R), and the CEMS response at each calibration point (A), expressed as a percentage of the span.  Calibration Error must be less than 5 percent.

       6.9.7 Extractive CEMS calibration error check.

                              6.9.7.1 Conduct a 3-point system calibration error test by sequentially flooding the probe and instrument with different known concentrations of HCl gas so that no source gas is included in the measurement. HCl gases should be measured in the range of concentrations shown in Table 3. Introduce calibration standards in any order.  Do not introduce the same calibration standard twice in succession.

                              6.9.7.2 At each reference gas concentration, determine the average of the three CEMS responses and subtract the average response from the reference gas value.  Calculate the calibration error using Eq. 3 in Section 12.   

                              6.9.7.3 If you desire to determine the system response time during this test you may inject the low-level calibration standard immediately followed by the high-level standard.

                              6.9.7.4  For non-dilution systems, you may adjust the system to maintain the correct flow rate at the analyzer during the test, but you may 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 you may make only the adjustments necessary to maintain the proper ratio.

       6.9.8 Integrated path CEMS calibration error check:

                              6.9.8.1   Conduct a 3-point system calibration error test by sequential addition of  known concentrations of HCl standard followed by zero gas into an inline calibration cell of known volume, temperature, pressure and path length. Note: Zero gas measurements must include native stack concentration measurement.

                              6.9.8.2 Use HCl standards in a range of concentrations that produce response equivalent to the source concentrations shown in Table 3 for your integrated path length.

                              6.9.8.3  Introduce the low-, mid-, and high-level calibration standards in any order. Do not introduce the same gas concentration twice in succession. 

                              6.9.8.4 You must calculate the relative concentration of the traceable HCl calibration gas equivalent to the stack concentration by correcting for calibration cell temperature, pressure, and path length.

                              6.9.8.5 Verify that the measurement is stable by collecting three consecutive independent measurements for each calibration gas, at least 2 minutes apart. 

                              6.9.8.6 At each reference gas concentration, determine the average of the three independent CEMS measurement responses and subtract the average response of the zero and reference gas value.  Calculate the calibration error using Eq. 4 in Section 12.

       6.9.9 You may use Figure 2 to record and report your calibration error test results.

       6.9.10 If the calibration error specification is not met for all three standard concentrations, take corrective action and repeat the test until an acceptable 3-point calibration error test is achieved.

          10.3 Seven-Day Calibration Drift (CD) Test

       6.9.11 CD Test Period. Prior to the start of the relative accuracy tests, you must perform a calibration drift test at zero and span concentrations.  The purpose of the CD measurement is to verify the ability of the CEMS to maintain calibration for each of seven, 24 hour periods.  

       6.9.12 Conduct the calibration drift test during normal facility operations. 

       6.9.13 If periodic automatic or manual adjustments are made to the CEMS zero and upscale response settings, conduct the daily CE test immediately before these adjustments. Note: automatic signal or mathematical processing performed on all measurement data to determine emission results may be performed throughout the entire CD process.

       6.9.14 The calibration drift tests must be performed using the zero and either mid-level or high-level calibration standards as defined in Table 3. 

       6.9.15 Determine the magnitude of the CD once each day (at 24-hour intervals, to the extent practicable) for 7 consecutive unit operating days.  The 7 consecutive unit operating days need not be 7 consecutive calendar days. You may use Figure 1 to record and report the results of your calibration drift test.

       6.9.16 Extractive CEMS calibration drift checks:

                              6.9.16.1 Sequentially introduce the certified zero or calibration standard gases to the CEMS at the sample system immediately preceding the sample extraction filtration system. Gases should be added in sufficient flow rate to replace all of the source gas sample. Continue to add the drift check standard until two consecutive measurements are within 5 percent the record the CEMS response.

                              6.9.16.2 Record the CEMS response for each reference gas, (A), for each reference gas.  Calculate the calibration drift by subtracting the corresponding reference concentration value (Ri) from the measured CEMS value using Eq. 5 in Section 12.  Report the absolute value of the differences as a percentage of the span value.
 
       6.9.17 IP-CEMS calibration drift checks:

                              6.9.17.1  Sequentially introduce certified zero and calibration standards into a permanently mounted calibration cell located in the optical measurement path of the instrument. Continue to flush each drift check standard into the cell until two consecutive measurements taken at least 2 minutes apart are within 5 percent. Measured concentrations must be corrected for calibration cell temperature, pressure, and path length.  

                              6.9.17.2 Record the CEMS response for each reference gas, (A), for each reference gas.  Subtract the average ppm response of the zero and calibration standard gas from the  reference gas value.  Calculate the calibration drift using Eq. 6 in Section 12 and express the absolute value of the differences as a percentage of the span value.

       6.9.18 The zero-level and high-level drift for each day must be less than 5 percent of span. You must pass each day's drift check for seven days to meet this requirement. Each zero- and high-level drift check must be recorded and reported for the seven day drift check tests. 

          18.3 Stratification Test. A stratification test must be conducted during normal facility operating conditions. The purpose of this test is to verify that excess stratification of the target pollutant does not render sampling point of the CEMS non-representative.
 
       6.9.19 If an isokinetic reference method (RM) is used for the RA testing required in section 11.7 you may determine whether effluent stratification exists using an RM while traversing the stack following the requirements in 40 CFR Part 60 Method 1.

       6.9.20 You may substitute a stratification test for sulfur dioxide (SO2) for the HCl stratification test if you expect HCl concentration to be less than three times the LOD of your test procedure.  If you select this option follow the test procedures in Section 6.5.6.1 of appendix A to part 75 of this chapter.  

       6.9.21 You may substitute a stratification test for O2, CO2. CO or NOx if you anticipate the concentration of both SO2 and HCl is less than three times LOD.

       6.9.22 Calculate the mean measured concentration for all sampling points (Cave).
 
       6.9.23 Calculate the percent stratification as the difference between the stationary measurement point and each traverse point (taken simultaneously) using Eq. 7 in Section 12.
 
       6.9.24 If the mean pollutant concentration at each traverse point differs from the mean concentration by no more than 10 percent the gas stream is considered unstratified or minimally and you may collect samples from a single point that most closely matches the mean.

       6.9.25 If the mean pollutant concentration at each traverse point differs by more than 10 percent the gas stream is considered stratified and the tester must select another sampling location that meets the stratification criteria.
 
          25.3 Relative Accuracy Using a Reference Method

       6.9.26 Unless otherwise specified in an applicable subpart of the regulations, Method 26A, Method 320 or Method 321, are the reference methods for HCl measurement. Other reference methods for moisture, oxygen, etc. may be necessary. When Method 26A is used, conduct the RM test runs with paired or duplicate sampling systems and use the average of the HCl concentrations measured by the two trains.

       6.9.27 Conduct the RM tests in such a way that they will yield results representative of the emissions from the source and can be compared to the CEMS data. Method 320/321 must be conducted by collecting gas samples that are at stack conditions (hot and wet). Conduct the diluent (if applicable), moisture (if needed), and pollutant measurements simultaneously. However, diluent and moisture measurements that are taken within an hour of the pollutant measurements may be used to calculate dry pollutant concentration and emission rates. 

       6.9.28 In order to correlate the CEMS and RM data properly, record the beginning and end of each RM run (including the exact time of day) with the permanent record of CEMS output.
       6.9.29 Conduct the RA test at the affected facility during normal operation, or as specified in an applicable subpart. 

       6.9.30 Conduct a minimum of nine sets of all necessary RM test runs. When you use Method 26A, you must sample sufficient gas to reach your quantitation limit for Method 26A or for a minimum of one hour whichever is greater.

                              6.9.30.1 When Method 26A is used, outliers are identified in the paired data through determining the relative deviation (RD) for the paired RM tests.  Data that do not meet the RD criteria may not be used in the calculation of RA.  The primary reason for performing paired RM sampling is to ensure the quality of the RM data.  Determine the RD for paired data points using Eq. 8 in Section 12.

                              6.9.30.2 The minimum performance criteria for RM paired HCl data is an RD for any data pair of <= 10 percent.  Pairs of RM data exceeding these RD criteria must be eliminated from the data set used to develop the HCl RA assessment.

NOTE: More than nine sets of RM tests may be performed. If this option is chosen, a maximum of three sets of the test results may be rejected so long as the total number of test results used to determine the RA is greater than or equal to nine. However, all data must be reported, including the rejected data. 

       6.9.31 Analyze the results from the RM test runs using equations in Section 12.10 (Equations 9  -  14).  Calculate the RA between the CEMS results and the RM. The RA for the average of nine independent measurements may not exceed 20 percent of span.
      
          31.3  Relative Accuracy Determination Using Dynamic Spiking.  Dynamic spiking is a gas phase method of standard additions which includes adding a known quantity of HCl into the measurement system, similar to system calibration, except the CEMS measurement includes both the native sample and the spiked addition. You must measure the combination of a known quantity of calibration gas and sample gas with the CEMS during normal facility operation. You must calculate the mean and relative standard deviation for the six (or more) dynamic spiking measurements to determine CEMS accuracy and compare the average to the specifications in Section 13.

.1.1       Spiking Gas Requirements.  You must use HCl calibration gas certified by an EPA traceability protocol or traceable to an NIST standard.  For extractive CEMS, you must add no more than 10 percent of the total volumetric flow rate through the CEMS. 

.2.2       Target Spiking Level.  The target level for spiking that you measure must be 20 to 40 percent of span after addition into the CEMS. You may perform dynamic spiking with EPA protocol gas, humidified protocol gas, or liquid evaporative HCl gas generation.

.3.3       Spike Additions.
  
                  3.1.3.1  Your spike addition may not alter the total volumetric sample system flow rate for extractive CEMS or the optical path length for integrated path CEMS. 

                  3.2.3.2 You must collect at least 6 sets of measurements. Each measurement must be a minimum of at least a 1 minute average.

                  3.3.3.3 You must collect a pre and post-spike measurement of native HCl concentration for each spike measurement.

                  3.4.3.4 As an alternative you may use two independent CEMS, one temporary unit unspiked to measure background/native HCl while simultaneously using the permanent CEMS to measure the spike plus background/native concentration.

.4.4       Spike Dilution Factor (DF).  If you dilute your calibration gas or spike by means of liquid standard evaporation, you must determine the dilution factor for each dynamic spike.  DF is the ratio of the spiking standard concentration to the final concentration spiked into the CEMS.  Since the spiking mass balance calculation is directly dependent on the accuracy of the DF determination, high accuracy is required for the total volumetric flow rate and spike gas flow rate measurements.  NIST traceable flow meters, venturies, orifices accurate to within 2 percent or certified tracer gas measurements are required to make the necessary flow rate determination at the accuracy required for this performance specification. You must document the quantitative uncertainty of HCl spikes or calibration gas into the system using Method 205.

.5.5       Calibration Error Adjustment Option.  You may adjust the measurement data collected during dynamic spiking for the system calibration error using Eq. 15 in Section 12.  You may perform the calibration check prior to the dynamic spiking test, and perform another calibration check following the dynamic spiking test. If you choose this option, you must apply Eq. 15 to both the spiked sample concentration and the baseline or native concentration measurements each substituted in place of Cavg in the equation.

.6.6       Spike Recovery.  Compare the mass recoveries from stable CEMS responses based on spiked concentrations compared to known concentrations injected into the CEMS. Procedures to perform and assess the accuracy of either extractive or integrated path CEMS are included in this section and the calculation and data analysis requirements found in Section 12. 

Note: For cases where the emission standard is expressed in units of lb/MM Btu or corrected to a specified O2 or CO2 concentration, an absolute accuracy specification based on a span at stack conditions may be calculated using an average concentration and applicable conversion factors. The appropriate procedures for use in cases where a percent removal standard is more restrictive than the emission standard are the same as in PS-2, Section 12.5 and 13.2.

.7.7        Extractive CEMS Dynamic Spiking Procedure

                  7.1.7.1 For extractive CEMS you must introduce the spike gas into the permanent CEMS probe, upstream of the particulate filter or sample conditioning system and as close to the sampling head as practical.

                  7.2.7.2 You must monitor the spiking and measurement systems to ensure the total sampling system flow rate and sample dilution ratio (if applicable) are known and do not change during the spiking procedure.  Record all data on a data sheet similar to Table 4 in Section 17.  

                  7.3.7.3 You must either measure the spike gas flow and the total flow with a calibrated flow monitor capable of NIST traceable 2 percent accuracy or calculate the flow using an independent stable tracer included in your spike gas standard.

                        3.1.7.3.1 If you use flow measurements to determine the spike dilution then use Eq. 16 in Section 12 to calculate the dilution factor. Total probe flow measurement requires measurement of HCl spike flow (Qspike) plus total flow through the CEM sampling system (Qprobe). 

                        3.2.7.3.2 If your CEMS is capable of measuring an independent stable tracer you may use a spike gas that includes the tracer to determine the dilution factor using Equation 17 in Section 12. 

                  7.4.7.4 Begin collecting measurements of 2 independent unspiked samples. Measurements must agree within 5 percent to be valid. 
      
                  7.5.7.5 Introduce the HCl gas spike into the extractive probe, upstream of the particulate filter and any sample conditioning system.  Collect measurement data from the spiked gas stream until sequential measurements are within 5% of each other. 

                  7.6.7.6 Collect measurements of 2 independent spiked samples.  If the spikes persistently show poor repeatability, or if the recoveries are not within the range specified in Section 13 you must take corrective action and repeat the dynamic spiking accuracy procedure.

                  7.7.7.7 Repeat the collection of sample measurements in Section 11.8.6.1.1 through 11.8.6.1.6 until you have six sets of data.  Calculate the relative accuracy for extractive CEMS as described in Section 12.12.

                  7.8.7.8 Dynamic Spiking Procedure for Integrated Path CEMS.

                        8.1.7.8.1 For IP CEMS you must spike a known quantity of calibration gas into a calibration cell that is in the optical path used to make CEMS source measurements.

                        8.2.7.8.2 Use calibration gas at a concentration that produces a signal equivalent to 20 to 40% of the span.

                        8.3.7.8.3 Sequentially introduce certified zero and the calibration standard into a permanently mounted calibration cell located in the optical measurement path of the instrument. Continue to flush each standard into the cell until two consecutive measurements taken at least 2 minutes apart are within 5 percent. Then collect measurements of 2 independent sample measurements. 

                        8.4.7.8.4 Repeat the collection of sample measurements in Section 11.8.6.2.1 through 11.8.6.2.3 until you have six sets of data. Measured concentrations must be corrected for calibration cell temperature, pressure, and path length. Calculate the relative accuracy for extractive CEMS as described in Section 12.13.

                  7.9.7.9 If the spikes persistently show poor repeatability, or if the recoveries are not within the range specified in Section 13 you must take corrective action and repeat the dynamic spiking accuracy procedure.

 7.9 Reporting

1.7.1 At a minimum (check with the appropriate EPA Regional Office, State or local Agency for additional requirements, if any), record and summarize in tabular form the results of the calibration drift, the linearity tests, the response time, calibration error, and RA test or alternative spiking procedure, as appropriate. Include all data sheets, calculations, CEMS data records (i.e., charts, records of CEMS responses), and cylinder gas or reference material certifications necessary to confirm that the performance of the CEMS met the performance specifications.

2.7.2 Record and report supporting dilution system data including standard cylinder gas flow, total gas flow, and the results of the test measurements.

      11.0 Calculations and Data Analysis

 2.1 Nomenclature

Cdif avg	= average of the 3 absolute values of the difference between the measured HCl concentrations of the reference HCl calibration gas, with and without the individual or combined interference gases, ppmv.
Cma	= Actual concentration of the upscale calibration gas used for the calibration checks, ppmv.
CSpike	= Concentration of the spike gas (ppmv)
Cs	= measured concentration of a calibration gas (zero-, low-, mid-, or high-level), when introduced in system calibration mode, ppmv.
CTdir	= Tracer gas concentration injected with spike gas, ppm.
CTv	= Diluted tracer gas concentration measured in a spiked sample, ppmv.
CC 	= confidence coefficient,
CDcorr	= the calibration drift correction (ppmv)
CDextractive 	 = calibration drift for extractive CEMS (percent),
CDintegrated path	= calibration drift for integrated path CEMS (percent),
CEextractive	= calibration error for extractive CEMS (percent),
CEintegrated path	= calibration error for integrated path CEMS (percent),
Cspikei,eff	= Equivalent concentration of the reference value, Ri, at the specified conditions
davg 	= mean difference between CEMS response and the reference gas (ppmv),
di 	= difference of one minute average CEM response and the average reference method or the spiked reference gas concentration (ppmv),
DF	= spiked gas dilution factor
I	= total interference from major matrix stack gases
LSM	= Line strength factor, temperature dependent derivation from the HITRAN database. 
Mave 	= average concentration at all sampling points,
MC0	= average of pre- and post-run system calibration check from the zero gas, ppm
MCi 	= Measured average response of CEMS to calibration gas concentration i (ppmV),
MCint	 = measured HCl concentration of the reference HCl calibration gas plus the individual or combined interference gases, (ppmv).
MCm	= Average of pre- and post-run calibration check responses for high-level calibration gas, ppmv.
MCss	= Measured concentration of the spiked HCl sample gas(ppmv)
MCnative	= Average measured concentration of the native HCl (ppmv)
MCTnative	= Measured tracer gas concentration present in native effluent gas, ppm.
MCzero	= Measured response of CEMS to zero gas spike (ppmv),
MNi	= the measured native concentration for test or run i
MCbaseline 	= average HCl concentration measured before and after dynamic spiking injections, ppmV
MCi 	= measured concentration or velocity at sampling point I,
n 	= Number of measurements in an average value,
Qspike	= the flow rate of the dynamic spike gas (Lpm)
Qprobe	= Tflowavg	= Average Total flow through the system (Lpm),
Ra	= the HCl concentration measured by one of two reference method pairs
Rb	= the HCl concentration measured by the second of two reference method pairs
RA	= Relative accuracy of CEMS compared to a reference method
RD	= relative difference between paired reference method trains
Ri 	= Reference Method or spiked reference gas concentration (ppmv),
RMi	= reference method concentration for test i
RMave 	= The mean value measured by the reference method or the mean dynamic spike concentration.
S 	= Span of the instrument (ppmv)
SA	= relative spike recovery accuracy
Sd 	= the standard deviation of the differences,
SRave	= Mean dynamic spike recovery (percent)
SRi	= Dynamic spike recovery (percent)
St 	= percent stratification,
t0.975 	= the one sided t-value obtained from Table 5 for n-1 measurements,
Treference	= Temperature of the calibration cell
Tstack	= Temperature of the stack at the monitoring location for an IP-CEM
yi 	= One minute average value of the CEM response (in ppmv),



 2.2       Calculate the difference between the measured HCl spike concentration with and without interferents for each interference gas (or mixture) for your CEMS as:

		Cdifavg=13Ci-MCint3 	Eq. 1

 2.3       Calculate the total interference as:

I=CdifavgCi*100		Eq. 2


 2.4       Calculate the calibration error for extractive CEMS as:

CEextractive=Ri-MCi S*100		Eq. 3

 2.5       Calculate the calibration error for integrated path CEMS as:

CEIntegrated Path=Ri-MCi-MCzero S*100	Eq. 4

 2.6       Calculate the calibration drift for extractive CEMS using as:

CDextractive=Ri-MCi S*100		Eq. 5

 2.7       Calculate the calibration drift for integrated path CEMS as:

CDIntegrated Path=Ri-MCi-MCzero S*100	Eq. 6

 2.8       Calculate the percent stratification as:

St=MNi-MaveMave *100		Eq. 7

 2.9       Calculate the relative difference between paired reference method sampling train results as:

RD= Ra-RbRa+Rb*100  		Eq. 8

 2.10       Calculate the Relative Accuracy using RM and CEMS Data.
 
1.7.1  Determine the CEMS final integrated minute average pollutant concentration or emission rate for each RM test period. Consider system response time, if important, and confirm that the results have been corrected to the same moisture, temperature, and diluent concentration basis.
 
2.7.2  When Method 26A is used, compare each CEMS integrated average value against the corresponding average of the paired RM values.

3.7.3  If the RM is a time integrated sampling technique (e.g., Method 320/321), make a direct comparison of the RM results and CEMS integrated minute average value for each test period.

4.7.4   Calculate the arithmetic difference of the RA measurements to the CEMS one minute average results using equation 9.

	di= RMi-MNi 			Eq. 9

5.7.5   Calculate the standard deviation of the differences (Sd) of measured and reference method results using Eq. 10.

      Sd=1ndi2-1ndin2n-11/2		Eq. 10

6.7.6   Calculate the confidence coefficient, (CC) for the relative accuracy tests using Eq. 11.
CC=t0.975*Sdn1/2 		Eq. 11

7.7.7   Calculate the mean difference (davg) between the RM and CEMS values in the units of ppm or the emission standard using Eq. 12.

davg= 1ndi  				Eq. 12

8.7.8   Calculate the average reference method value using Eq. 13.

RMavg= 1n i=1nRMi			Eq. 13

9.7.9   Calculate the relative accuracy (RA) for the CEMS using equation 14.

RA=davg+CC/RMavg*100	Eq. 14

       
 9.2  Calculate the calibration drift correction as: 

       CDcorr=MCavg-MC0*CmaMCm-MC0		Eq. 15



    2.12 Relative Accuracy using Dynamic Spiking Test Data from Extractive CEMS. 

1.7.1  If you determine your spiking concentration on the basis of source gas and spike standard gas flow measurements, calculate the dilution factor for extractive dynamic spiking accuracy tests based using Equation 16: 

DF= QprobeQspike 		Eq. 16  

2.7.2  If you base your spiking concentration on tracer gas dilution, calculate the dilution factor for extractive dynamic spiking accuracy tests using Equation 17: 

DF = CTdir-MCTnativeCTv-MCtnative 		Eq. 17  

3.7.3  Calculate the average measured concentration of the native HCl in one of the following two ways: 

      1.7.3.1 For dynamic spiking procedures that include flushing the extractive measurement system at the spiking flow rate (Qspike) with zero gas between spike measurements use Equation 18.

	MCnative= MCbaselineDFDF-1  		Eq 18

      2.7.3.2 For dynamic spiking procedures that halt all addition of dynamic spike gas flow, between spike measurements, the native concentration equals the average baseline concentration (Equation 19) 

MCnative=MCbaseline 		Eq 19

4.7.4  Calculate the percent spike recovery (SRi) between the CEMS results and the reference concentration for each spiked sample measurement using Equation 20. 

SRi= DFMCss- MCnative+ MCnativeCSpike*100% 	Eq. 20

5.7.5  You must calculate the mean of the recovery for the six (or more) dynamic spikes using Equation 21.

SRavg= 1n i=1nSRi			Eq. 21


6.7.6  You must calculate the standard deviation for the six (or more) dynamic spiking measurements to determine CEMS accuracy using Eq. 22.  

	Sd= i=1n(SRi- SRavg) 2n-1			Eq.22 

7.7.7  Calculate the confidence coefficient, (CC) for the relative accuracy tests using Eq. 23.

	CC=t0.975*Sdn1/2 		Eq. 23

8.7.8  Calculate the relative spike recovery accuracy (SA) for the CEMS using equation 24.

SA=SRavg+CC/Cspike*100	Eq. 24

9.7.9  If the spike recovery analysis passes the validation criteria, then the accuracy evaluation is completed. 

Note: If the results do not pass the criteria, temporal variations in the sample gas may be excessive relative to the interval between measurements. Temporal variation may be reduced by:

::	Averaging the measurements over long sampling periods and using the averaged results in the statistical analysis,
::	Reducing the total system response time for extractive CEMS sampling systems, for example, using a smaller volume extractive cell or increasing the sample flow rate.
::	Using two separate sampling lines (and pumps) for extractive CEMS; one line to carry unspiked flue gas and the other line to carry spiked flue gas to decrease the equilibration time in the lines. Both sampling lines include independent flow measurement and are continuously purged.  Even with two sampling lines the variation in unspiked concentration may be fast compared to the interval between consecutive measurements.

    9.12       Relative Accuracy using Dynamic Spiking Test Data from Integrated Path CEMS.

10.7.10  If you use an in-situ IP-CEMS and a calibration cell, calculate and substitute the equivalent Ri using equation 25. 

C - Spike i,eff=CSpikexCalibration Cell PathlengthStack PathlengthxTstackTreferencexLSM		Eq. 25

11.7.11  Calculate the percent spike recovery (SRi) between the CEMS results and the reference concentration for each spiked sample measurement using Equation 26.

SRi= MCss- MCnative+ MCnativeCSpike i, eff*100% 	Eq. 26

12.7.12  Calculate the average spike recovery (SRavg) using Equation 21.

13.7.13  Calculate the standard deviation for the six (or more) dynamic spiking measurements to determine CEMS accuracy using Equation. 22.  

14.7.14  Calculate the confidence coefficient, (CC) for the spiking accuracy using Equation 23. 

      1.7.14.1 Calculate the relative spike recovery accuracy (SA) for the integrated path CEMS using Equation 27.

SA=SRavg+CC/Cspike i,eff*100		Eq. 27

      2.7.14.2  If the spike recovery analysis passes the validation criteria, then the accuracy evaluation is completed.

      12.0 Method Performance

7.1 The Calibration drift for the HCl CEMS must not drift or deviate from the reference gas value by more than 5 percent of the span value for 7 consecutive days (Eq. 2).

7.2 Calibration Error Check, (linear or quadratic) 

      1.7.2.1 The Calibration intercept must be equal to or less than 15% of the instrument's span. 
 
      2.7.2.2 The mean percent difference between the reference gas value and the CEMS measured concentration at each of the three points (Eq.7) must be less than 5 percent of span.

7.3  Relative Accuracy Check  -  Reference Method 

      1.7.3.1 The  RA of the CEMS compared to a reference method in the units of the emission standard, must be less than or equal to 20 percent of the reference method when RMavgis used in the denominator of Equation 14 or

      2.7.3.2 In cases where the average emissions for the test are less than 50 percent of the applicable standard, substitute the emission standard value in the denominator of Eq. 14 in place of RMavg and the  RA must be less than or equal to 15 percent of span. 

7.4 Spike Accuracy Check - Dynamic Spiking

1.7.1 The accuracy of the CEMS compared to a reference gas in the units of the emission standard must be less than or equal to 20 percent of spiked sample concentration.

2.7.2 The SA for the average of six (or more) independent measurements may not exceed 15 percent of span.

16.0 References.

1. Method 318, 40 CFR, Part 63, Appendix A (Draft), "Measurement of Gaseous Formaldehyde, Phenol and Methanol Emissions by FTIR Spectroscopy," EPA Contract No. 68D20163, Work Assignment 2-18, February, 1995.

2. "EPA Protocol for the Use of Extractive Fourier Transform Infrared (FTIR) Spectrometry in Analyses of Gaseous Emissions from Stationary Industrial Sources," February, 1995.

3. "Measurement of Gaseous Organic and Inorganic Emissions by Extractive FTIR Spectroscopy," EPA Contract No. 68-D2-0165, Work Assignment 3-08.

4. "Method 301 - Field Validation of Pollutant Measurement Methods from Various Waste Media," 40 CFR 63, App A.

5.  EPA Traceability Protocol for Assay and Certification of Gaseous Calibration Standards 2012. See www.epa.gov/ttn/emc.

17.0 Tables, Diagrams, Flowcharts, and Validation Data.

Table 1: Interference Check Gas Concentrations
Potential Interferent Gas [1]
Approximate Concentration (balance N2)
CO2 
15% +- 1% CO2
CO 
100 +- 20 ppm
CH4
100 +- 20 ppm
NO2
250 +- 50 ppm
SO2 
200 +- 20 ppm
O2 
3% +- 1% O2
H2O 
10% +- 1% H2O
Nitrogen 
Balance
Other


1 Any of these specific gases can be tested at a lower level if the manufacturer has provided reliable means for limiting or scrubbing that gas to a specified level.

Table 2: Example Interference Test Data Sheet

Date of Test: ____________________________________________
Analyzer Type: __________________________________________
Model No.: _____________________________________________
Serial No.: ______________________________________________
Calibration Span: ________________________________________
Test Organization: _______________________________________
Test Personnel: __________________________________________

                                 Interference
                            Gas or Gas Combination
                           HCl Concentration (ppmv)
                  HCl Concentration (ppmv) w/Interference Gas
                              Absolute Difference
                                    (ppmv)
                               Average Absolute
                                  Difference
                                    (ppmv)









































































































                                                               Sum of Responses

                                                          % of Calibration Span



Table 3. Performance Specification Test Calibration Gas Ranges



                  HCl Calibration Material Concentrations [a]
                                       
                                       
                                     Test
                                     Units
                                     Zero
                                   Low Level
                                   Mid Level
                                  High Level
                                    Section
Calibration Drift  
                                   % of Span
                                    <LOD
                                   10  -  50
                                      NA
                                   190 - 200
                                     11.5
Calibration Error Test 
                                  % of Span 
                                   <LOD 
                                   10  -  50
                                  80  -  100
                                  190  -  200
                                     11.4
Relative Accuracy Spiking 
                                  % of Span 
                                    <LOD
                                   10  -  50
                                  80  -  100
                                   190 - 200
                                     11.6
a  Reference calibration material concentration must meet EPA Protocol Gas requirements or be NIST traceable.
                                       
Table 4 Spike Recovery Work Sheet
Facility name:
Date:
Time:
Unit(s) tested:
Test personnel:
Analyzer make and model:
:
Serial number:

Calibration span:


Qprobe
(lpm)
Qspike
(lpm)
DF[1]
                                    Cnative
Actual Values
 SR
(% Spike Recovery)



Pre
Post
Avg.
Cspike
(ppm)
Css
(ppm)


































































































Avg








SD


1 DF must be <= 10
Cspike = Actual HCl concentration of the spike gas, ppmV.
Css = Measured HCl concentration of the spiked sample at the target level, ppmV.


                              
TABLE 5. t-VALUES

                                    n-1[a]
                                    t-value
                                     n-1 a
                                    t-value
                                     n-1 a
                                    t-value
                                     n-1 a
                                    t-value
                                       5
                                     2.571
                                      11
                                     2.201
                                      17
                                     2.110
                                      23
                                     2.069
                                       6
                                     2.447
                                      12
                                     2.179
                                      18
                                     2.101
                                      24
                                     2.064
                                       7
                                     2.365
                                      13
                                     2.160
                                      19
                                     2.093
                                      25
                                     2.060
                                       8
                                     2.306
                                      14
                                     2.145
                                      20
                                     2.086
                                      26
                                     2.056
                                       9
                                     2.262
                                      15
                                     2.131
                                      21
                                     2.080
                                      27
                                     2.052
                                      10
                                     2.228
                                      16
                                     2.120
                                      22
                                     2.074
                                      28
                                     2.048

 a The value n is the number of independent pairs of measurements (a pair consists of one spiked and its corresponding unspiked measurement). Either discreet (independent) measurements in a single run, or run averages can be used.

                                       


SOURCE:
DATE:
 CEMS:
LOCATION:
SERIAL NUMBER:
SPAN:


DAY
DATE
TIME
CALIBRATION
VALUE
 CEMS
RESPONSE
DIFFERENCE
PERCENT
OF SPAN
 ZERO/LOW LEVEL
1







2







3







4







5







6







7






 HIGH LEVEL
1







2







3







4







5







6







7






   1. Acceptance Criteria: <15% of span for seven days.

                   Figure 1 Calibration Drift Determination

SOURCE:
DATE:
 CEMS:
LOCATION:
SERIAL NUMBER:
SPAN:

                                      RUN
                                    NUMBER
                               CALIBRATION VALUE
                                      CEMS
                                   RESPONSE
                                  DIFFERENCE



                                   Zero/Low
                                      Mid
                                     High
1





2





3





4





5





6





7





8





9






                                                              Mean Difference =




                                                            Calibration Error =
                                                                              %
                                                                              %
                                                                              %


                   Figure 2: Calibration Error Determination

