LAWR

SOURCE TESTING ASSOCIATION | Annual Guide 2015 6 maining QA requirements are satisfied (QAL2, AST and QAL3), noting that the pass criteria become more stringent as the daily ELV is reduced. Existing certified instruments that cannot meet the for- mal uncertainty requirements due to a reduction in the ELV, e.g. due to new IED requirements, may be approved by the competent authority, e.g. on the basis that the remaining QA requirements are satisfied (QAL2, QAL3, AST). For existing instruments that do not formally meet the certification requirements, the operator should consider measures to reduce the measurement uncertainty, e.g. air conditioning the AMS shelter. Normative reference to EN 15259 [8] has been added. Representative sampling points for AMS & SRM must be defined and there must be no interference or disturbance between the AMS & SRM. In some cases, the existing duct work may be horizontal and readily accessible (Figure 2). e Standard does not ad- dress the problems at existing plant where it can be imprac- tical to meet the full requirements of EN 15259 with re- gards to sample ports and sampling platforms and the operator will then need to agree alternative provisions with the competent authority, noting that the IED (Article 38) requires the competent authority to 'determine the location of the sampling or measurement points'. Quality Assurance Level 2 and the Annual Surveillance Test Functional tests: Functional tests are now identical for both QAL2 and AST testing and are also recommended for peripherals (O 2 , and H 2 O). It is recommended that functional checks are carried out not more than one month prior to the QAL2 or AST. Functional testing must be performed by an experienced testing laboratory that has been recognised by the compe- tent authority. e linearity test range is at 'least the short term ELV' rather than being 'two times the emission limit', thus pro- viding greater flexibility in the concentration range that can be considered in relation to concentration excursions. e response time of the AMS must continue to meet the EN 15267-3 performance criterion, rather than the historic actual QAL1 result, that is, degradation of the instrument in-service is now recognised along with the need to remove in-situ analysers from the stack to conduct a zero and span check. Documentation must now include details of the AMS certification. QAL2/AST testing An AST may replace a repeat QAL2 provided that the AST measured values and at least 95% of the AMS short term averages, reported since the previous AST, are both less than MPU. ere is a recommendation that QAL2 can be applied to peripherals (O 2 and H 2 O). However, the Stand- ard does not point out that there may be genuine differ- ences between peripheral measurements at two locations so it may not be appropriate or necessary to apply QAL2 factors under these circumstances. Water vapour values from a calibrated AMS or a calculated water vapour (for wet abatement systems) can be used to cor- rect SRM measurements to a wet or dry basis as required. Excluded outliers must be identified, reported and re- tained in data tables and calibration graphs, noting that the assessment method, and the justification for excluding out- liers, are to be documented in the QAL2/AST report. It is recommended that additional test points, beyond the mini- mum requirements, are obtained to allow for outliers. Figure 2: Horizontal flue gas duct Exclusion of invalid data from the initial data set, prior to the outlier analysis, must also be justified in the QAL2/AST report, e.g. it is easy to justify the exclusion of start-up or transient data but all stable operating data during normal operation should usually be included. QAL2 calibration function ere is a requirement that the QAL2 calibration shall be implemented within six months, rather than it simply being reported within six months. However, it is noted that the member states may allow the continued use of the previous calibration function if it can be proven by use of a specified statistical procedure that the new calibration function does not significantly differ from the previous one. A new analysis procedure is defined for the treatment of low level data clusters (Method C). (is is based on Op- tion 4 from B.3 of Annex B of EN/TR 15983 [3] .) A calibra- tion function is derived from a combination of data from the parallel reference tests and reference materials. Two reference points (at zero and close to ELV) are added to the QAL2 data set prior to deriving the calibration function. However, the reference points are not included in the varia- bility test. If appropriate reference materials, e .g. test gases, are not available, an alternative procedure can be approved by the competent authority and this must be fully docu- mented in the QAL2 report. »

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