The European Directives that limit industrial air emissions require quality assurance standards for Continuous Emissions Monitoring Systems to be implemented. EN 14181 is a European standard which details the quality assurance procedures which are required to ensure that the emissions monitoring systems meet the measurement uncertainty requirements.
The full title for EN 14181 is ‘EN 14181 Stationary Source Emissions – Quality assurance of automated measuring systems’. In this title, automated measuring systems (AMS) is used instead of the more common Continuous Emissions Monitoring System (CEMS).
EN 14181 was first published in 2004 and it outlined criteria which should be uniform throughout the EU, rather than each member state enforcing their own standards, resulting in a culture change for the majority of Europe.
When EN 14181 was first released, the power industry highlighted areas where further development was needed. A CEN technical report was then issued in order to provide guidance on its implementation. A new version of EN 14181 was published November 2014 to elaborate on this guidance.
An Overview of EN 14181
EN 14181 specifies procedures to establish three Quality Assurance Levels (QALs) and an Annual Surveillance Test (AST). It covers the approval, calibration, testing and monitoring of measuring systems to ensure emissions monitoring equipment meet the requirements of legislation.
QAL1 – Analyser suitability and assessment of AMS equipment
All new analysers should undergo certification with a field trial similar to the conditions and process that it will undergo when put in position. The monitoring equipment needs to be placed so that an appropriate, representative reading can be made.
QAL2 – In-situ calibration
Following installation, AMS monitors should be calibrated against analytical methods applied by an accredited test laboratory, to demonstrate their suitability for application
ASTs – Annual Surveillance Tests
AST’s are used to validate calibration from QAL2. This is done by taking a reduced number of parallel measurements and employing an accredited test laboratory. The tolerance level of the data scatter is widened and a further test will compare the mean deviation from the calibration line. If the calibration remains within tolerance, no further action is needed.
QAL3 – audited check of operational performance
Regular zero and span checks of the monitors are conducted and compared against pre-defined warning and action limits. The data collected is plotted using control charts and these are used to determine the frequency that the instruments/equipment require maintenance.
The overall aim is to reduce industrial air emissions by ensuring that Continuous Emission Monitoring Systems are functioning to a high quality standard. After the release of EN 14181 in 2004, problems were identified within this standard and therefore some changes have been made to improve its applicability.
Look out for our blog where will discuss the amendments that have been made for EN 14181:2014