Certification of in situ gas chromatographs measuring Benzene in compliance with EN 14662-3 under UK MCERTS scheme

Certification of in situ gas chromatographs measuring Benzene in compliance with EN 14662-3 under UK MCERTS scheme

MCERTS scheme under Environment Agency and SIRA certification service was chosen with NPL laboratory to operate the required tests. The choice criteria is almost the ISO 17025 accreditation that is the assurance of European acknowledgement. The MCERTS Scheme certifies that the CAMS (Continuous Ambient air Monitoring System) of a manufacturer complies with the performance criteria of EN 14662-part 3 (Ambient Air Quality) Standard method for the measurement of Benzene concentration - automated pumped sampling with in situ gas chromatography.

The substance tested is Benzene but the number of substances tested has been increased in reference to the 31 VOC on the European list. The measurement range is between 5 µg/m3 (and 1/10 of this limit value for several tests) and 45 µg/m3.

Chromatotec has decided to certify 2 types of analysers at same time which increases the challenge of the certification because one single sample or standard cylinder is analysed by 4 instruments at same time.

  • AirToxic (PID detector) for Benzene Toluène, Ethylbenzene, m&p-Xylene, o-Xylene
  • AirmoVOC C6C12 (FID detector) for 12 VOC from European VOC list ranging from C6 to C12

These CAMS are completely autonomous and automatics and are driven by an internal PC.

The price of such certification is a significative investment. It is necessary to manufacture two of each type of instrument and to organise preliminary tests, commissioning at the accredited laboratory. Six months are necessary to perform all the tests.

Even if it is a big investment, Instrument certification is very beneficial technically and commercially to continue to improve instrument quality in term of metrology and trueness. This certification allows validation of Chromatotec international experience and allows to improve current trueness from ± 8% to ± 5%.

There are eleven criteria for lab tests. All of them have been successful met as certify the NPL letter

1. Lack of fit
2. Repeatability at 0,5 µg/m3
3. Repeatability at limit value
4. Influence of the interference of ozone
5. Influence of the interference from the sum of possible interfering organic compounds at span value
6. Influence of interference from relative humidity
7. Influence of surrounding temperature at span value
8. Influence of ambient pressure
9. Influence of voltage
10. Short term drift over 24 hours at span value
11. Carry over

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