Calibration of opacity filters for exhaust measurement systems

Hellma calibrates opacity filters of different brand and design types according to DIN EN ISO/IEC 17025

The amendment of the EU Directive 2014/45/EU for exhaust emission tests specifies that for all vehicles subject to regular exhaust emission tests, exhaust pipe tests are now a general requirement. Since the amendment has come into force on January 1st, 2019, the limit values for exhaust emissions for Euro 6 cars have been reduced. This means that the requirements for the accuracy of exhaust emission testing devices have increased significantly.

Not only have the requirements for exhaust emission testing devices increased, furthermore, from January 1st, 2019, a periodic calibration of those devices is also obligatory. This means that car repair shops now have to prove that their devices are verified by the authority as well as calibrated.

In order to guarantee the measuring accuracy, conformity and traceability to primary standards, the opacity filters (calibration filters) used must be recalibrated every 12 months by a calibration laboratory which is accredited according to DIN EN ISO/IEC 17025.

Services provided by the Hellma Calibration laboratory

  • Checking and cleaning of the opacity filters (calibration filters)
  • Adding a unique serial number to the calibration filter (if absent)
  • Measurement of the optical density at a wavelength of 560 nm and calculation of the appropriate opacity rate N (%)
  • Issuance of the calibration certificate according to DIN EN ISO/IEC 17025

A service of


Hellma USA Inc.
120 Terminal Drive
11803 Plainview, NY
United States

Phone: +1 5169 3908 88


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