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Green light for exhaust gas particle counting in German PTIs

Annual Report 2021
14.04.2022

For the exhaust examination of Euro 6/IV diesel vehicles, counting particles in diesel exhaust gas will become mandatory as of 2023. Vehicle workshops must prepare for this new type of examination. (Photo: Matt Boitor / Unsplash)

Improved air quality in city centers and climate protection – counting soot particles is to become an integral part of the exhaust examination of diesel cars within the scope of mandatory vehicle inspections in Germany (HU/AU). Based on the particle number density in diesel exhaust gas, it is possible to check whether the particle filter of a car is still in working order, and if so, how well it works. To ensure uniform instrument quality, PTB has drawn up and published metrological requirements for the required type certification of such particle counters in cooperation with the bodies concerned. Manufacturers of such exhaust particle counters can now retrofit their instrument prototypes to meet the PTB requirements. Workshop owners offering mandatory, bi-annual vehicle emission tests (AU) can ensure that they are equipped with such instruments before 1 January 2023 – the date on which the requirements will go into force. And in Europe, Germany’s neighboring countries now have a blueprint for developing similar solutions of their own. Based on this blueprint, the EU could even develop a harmonized European vehicle emission test that is similar to the already harmonized type approval of motor vehicles.

Particle measuring instruments have existed for many years. They are used, for instance, in atmospheric research and to measure aerosols. However, the measurement results obtained by means of these instruments are often not metrologically traceable; for workshops, the costs of these highly specialized instruments are much too high for them to be used in PTI scenarios. The challenge PTB faced was to develop requirements that would make particle counters sufficiently accurate and reliable while also allowing such counters to remain affordable for workshops and to be much simpler to use and more robust than former laboratory instruments.