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Stationary Source Emissions – Quality assurance of automated measuring systems (EN 14181)


  • Background
  • QAL1
  • QAL2
  • QAL3
  • AST
  • EmiDas and EN 14181


‘EN 14181 Stationary source emissions – Quality assurance of automated measuring systems (AMS)’ was first published in 2004 and was introduced by the Environmental Agency in the UK to ensure that sites which disperse emissions meet defined criteria by law.

EN 14181 refers to Automated Measuring Systems (AMS) which includes Continuous Emissions Monitoring Systems (CEMS).

EN 14181 supersedes the Large Combustion Plant Directive (LCPD) published in 2001 and the Waste Incineration Directive (WID) published in 2000.

As EmiDAS is MCERTS certified to Parts A,B,C1 and C2 of the EA Standard, it is also compliant for Continuous Emissions monitoring under the Automated Measuring Systems in BS EN 14181.

To comply with BS EN 14181, three Quality Assurance Levels (QAL) and one Annual Surveillance Test (AST) parts must be completed.

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QAL1 - Quality Assurance Level 1

QAL1 takes place pre installation and must show that the Automated Measurement System (AMS) / Continuous Emissions Monitoring System (CEMS) meets required performance standards and the uncertainty allowances specified in the WID and LPCD directives.

QAL2 - Quality Assurance Level 2

QAL2 is a real-time test to ensure that the CEM System is working in accordance with a set of expected results. For the tests to be valid the CEM system must run for a minimum of 3 days with each day being around 8 to 10 hours and must include a sample of at least 15 measurements. Standard Reference Methods (SRM) are run hourly to verify the performance of the CEMS and to trigger calibrations if required.

The results normally show:

  • A wide spread of data where the difference between the lowest and highest value is greater than 15% of the Emission Limit Value (ELV) (which is EN 14181 Method A).

  • A cluster of data, where the difference between the lowest and highest value is lower than 15% of the Emission Limit Value (ELV) (which is EN 14181 Method B).

  • A low level cluster of data, where the daily average for the Emission Limit Value (ELV) daily average is lower than the 95% confidence interval

EmiDAS allows for the input of QAL2 Calibration Functions where the CEMS readings are automatically corrected within the software in order to calibrate the readings to those obtained by the Test House during QAL2 testing using Standard Reference Methods (SRMs) as required by the Environment Agency.

QAL3 - Quality Assurance Level 3

QAL3 checks to ensure the continuous emissions monitoring system still meets the required conditions during actual day to day usage.

As required by EN 14181, EmiDAS allows the plant operator to regularly measure the drift and precision of the emissions data, either manually or via the instrument’s auto-calibration facilities. It is then possible to determine when the system still complies by using the Shewhart, CUSUM and EWMA Control Charts. If not, appropriate action must be taken.

AST - Annual Surveillance Test

The annual surveillance test (AST) is used to check that the findings from the QAL2 tests are still valid. The AST is a mini QAL2 test which consists of the same checks but on a smaller scale.

EmiDAS and EN 14181

EmiDAS is written to conform to BS EN 14181 and the European draft standard CEN/TC264 Stationary source emissions—Quality assurance of data obtained from automated measuring systems.

EmiDAS complies with BS EN 14181 and includes functionality to apply calibration functions generated by QAL2 testing and produce QAL3 control charts such as CUSUM, Shewhart and EWMA by storing the results of zero and span checks using certified test gases or reference materials.

The EmiDAS system has the optional ability to control the automatic injection of test gases using our Calibration Gas System (CGS).

EmiDAS offers all reports required by the regulations including: