Quality control of air quality monitoring equipment is necessary to ensure that the uncertainties of measured values remain within the established limits during periods of continuous measurement in the field.
To ensure that air quality data are accurate, reliable and traceable, it is crucial to carry out proper maintenance, verification and calibration procedures, but what are they consist about? and what importance and added value do they provide to the company?
Gas analyzers calibration, maintenance and verification definitions
In order to talk about calibration, verification and maintenance of gas analyzers, it is important to know what each of them consists of:
- Calibration: Calibration is the process of adjusting a measuring equipment to provide accurate and consistent readings. In this process, the output of the instrument is compared to a traceable reference standard. If any deviation is found, the necessary adjustment is made to correct the instrument reading.
- Verification: Verification involves checking that the analyzer measures accurately under normal operating conditions. This is done by comparing equipment readings with known reference values or standards. Verification is a fundamental step in ensuring the correct functioning of the analyzers.
- Maintenance: Maintenance of monitoring equipment refers to regular activities aimed at preventing deterioration and ensuring the proper functioning of the instruments. Maintenance can be corrective or preventive in nature and includes cleaning, replacement of worn parts and other adjustments necessary to maintain the accuracy and reliability of the equipment.
Maintenance, verification and calibration plan according to 2008/50/EC Directive
The European Directive 2015/1480/EC of 28 August 2015 that amends serveral annexes of 2004/107/EC and 2008/50/EC Directives, lays down rules on reference methods, data validation and the location of measurement points for ambient air assessment in EU member states.
In order to comply with the requirements of this directive with regard to maintenance, verification and calibration, it is necessary to implement continuous quality control and quality assurance procedures.
This procedures should include which parameters will be measured and monitored and on which equipment this will be carried out, including gas and particulate matter analyzers, weather stations…
Preventive and corrective maintenance plans must also be established for all measuring equipment, including:
- Regular check-ups and verifications
- Scheduled preventive maintenance
- Analyzers adjustment and repair procedures
Frecu3ency of calibrations, verifications and maintenances
The frequency of these procedur4es is directly linked to each parameter and each of them is determined in the corresponding UNE standard (the most commonly measured parameters are: CO, O3, SO2, NO, C6H6 and particulatte matter PM10 and PM 2.5).
However, as a general rule we can say:
Calibrations: calibration is essential to ensure the accuracy of the results. Calibration is generally carried out at least every 3 months to a year (depending on each parameter) and always after a repair that has been carried out.
Verifications: according to the different regulations, zero and span verifications must be performes at least every two weeks for gas concentrations. The outcome of these checks will determine if an immediate corrective action is required.
Checks for misadjustment of the analysers must also be carried out within one year after the initial installation test or after a repair.
Maintenance: preventive maintenance should be carried out regularly, following the manufacturer’s recommendations. This may be annual, semi-annual or even monthly depending on the application and environment of use.
On-site maintenance, verification and calibration service
To perform these maintenance, verification and calibration procedures on-site, it is very useful to have mobile calibration vehicles that allow these operations to be carried out in industrial environments where dismantling and sending instruments to a permanent laboratory is costly or unfeasible.
For this reason, on-site calibration laboratories provide comfort and minimise downtime, resulting in cost savings. They also allow calibrations to be performed under real conditions while the instruments are in their normal working and operating environment.
The combination of all the available resources, together with the technicians specialised in industrial maintenance, allows us to offer an agile, precise and effective gas analyzer calibration, verification and maintenance services.
Additionaly, Envira has a permanent laboratory and another on-site laboratory accredited by ENAC that work under the EN 17025 standard that offers a further guarantee in terms of calibration.
All this allows companies to guarantee accurate and reliable measurements that comply with the regulatory and legal requirements linked to each sector.
