LAWR

SOURCE TESTING ASSOCIATION | Annual Guide 2015 8 e criterion for selecting the calibration procedure (Method A, B or C) has changed. is was previously based on the SRM test data range (max – min) being less than 15% of ELV. It is now based on the data range being less than MPU. Valid Calibration Range (VCR) e VCR established under QAL2 continues to be defined as the highest, calibrated, AMS QAL2 concentration, at standard reporting conditions, plus 10%. If the emissions data, reported subsequently, lie outside of this range, for more than a specified proportion of the time, a repeat QAL2 is required. Industry has long argued that this range extension is insufficient to cover normal process variability. e VCR can now be extended using the highest AST data point (plus 10%) provided that the extension is less than 50% of ELV. e VCR can always now be extended to 20% of ELV (minimum VCR). As before, reference materials, e.g. test gases, can be used to improve confidence in data that lie beyond the VCR, although the emphasis is placed on concentrations close to the ELV rather than a wider extrapolation. e agreement between the high test gas concentration and the calibration line must be within the MPU. e agreement between the zero point and the calibration line must be within 10% of ELV. e competent authority must therefore determine if reference materials can be used to actually extend the VCR in addition to improving confidence. An extension to the short term ELV would be reasonable since this is the range across which the plant is expected to operate during normal operation. Weekly data inspection (Monday to Sunday), to check that reported data are within the VCR, can now be based on the most recent operational hours (168 hours), rather than a calendar week, when the plant is not run continuously. Also, exceedances of VCR caused by plant failures do not now trigger a QAL2. Quality Assurance Level 3 QAL3 requires operators to have a procedure that de- scribes the requirements for a) measuring zero and span values; b) plotting these values in control charts and c) using the control charts to determine if there is a system- atic deviation (drift). ere is an enhanced description of QAL3 requirements including the selection and use of control charts and the execution of zero and span measurements. ree examples of control chart are described in detail in Annex C of the Standard: Shewhart and CUSUM (included in EN 14181:2004) and an additional Exponentially Weighted Moving Average (EWMA) approach. In all cases, including dust monitors, alternative reference materials can be used, such as optical filters, provided that these are certified as being QAL3-compliant under EN 15267-3. ere is a new general requirement on the operator to ensure that AMS internal checks or compensation systems are active and operational and that AMS alarms are re- ceived by plant personnel so that corrective action can be taken at all times. Any type of manual or automated con- trol chart can be used. Built-in procedures are allowed as an alternative to an external QAL3, provided that the data is available to the operator to allow for annual auditing of the QAL3 data. e required frequency is at least once per maintenance interval and at least once per month for uncertified AMS. For maintenance intervals greater than one month, it is necessary to justify with internal checks and, for multi- component analysers, a monthly span check of at least one gas component is required. Hot spares (fully independent back-up AMS) can be used to extend QAL3 to an annual check provided that an alarm is raised when the difference between the two AMS is > 5% of the short-term ELV for more than five consecutive measurements. Control chart limits can be based on the MPU rather than a detailed uncertainty assessment. e alarm limit can- not be higher than 50% of MPU. e warning limit may be set at 25% MPU. For audit purposes, QAL3 documentation must include a history of the checks and the actions taken when exceed- ing control chart limits. Control charts should be stored for five years. Conclusions e amendment of EN 14181 clarifies and improves the applicability of this quality assurance Standard and this is a positive development that is welcomed by industry. ere are a few remaining issues, that have been identified pre- viously, that have not been addressed and that will require approval by the relevant competent authority for specific industrial sectors. ese include: i) not applying QAL2 calibration factors if the agreement between AMS and SRM is acceptable; ii) extending the Valid Calibration Range be- yond the Daily Emission Limit Value using reference mate- rials; iii) simplification of linearity test requirements for multi-component analysers. It should be noted that the progressive reduction of Emission Limit Values increases the difficulty of passing each of the QA requirements. Further details can be found in a related conference paper [9] . David Graham STA Chairman E.ON Technologies References 1. EN 14181, Stationary source emissions. Quality assurance of automated measuring systems. 2. Graham D P et al (2009), European Power Industry Experience of EN14181, CEM 2009: 9th International Conference on Emissions Monitoring, 23-25 September 2009, Stresa, Italy. 3. PD CEN/TR 15983:2010, Stationary source emissions. Guidance on the application of EN 14181:2004. 4. Directive 2010/75/EU of the European Parliament and of the Council of 24 November 2010 on industrial emissions (integrated pollution prevention and control). Official Journal of the European Union, L 334/17 to 119, 17/12/2010. 5. EN 15267-1:2009, Air quality. Certification of automated measuring systems. General principles. 6. EN 15267-2:2009, Air quality. Certification of automated measuring systems. Initial assessment of the AMS manufacturer's quality management system and post certification surveillance for the manufacturing process. 7. EN 15267-3:2007, Air quality. Certification of automated measuring systems. Performance criteria and test procedures for automated measuring systems for monitoring emissions from stationary sources. 8. EN 15259:2007, Air quality. Measurement of stationary source emissions. Requirements for measurement sections and sites and for the measurement objective, plan and report. 9. Graham D, Faniel N, et al, Changes to the Quality Assurance Standard EN14181, CEM 2014 International Conference on Emissions Monitoring, Istanbul, May 2014.

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