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Switzerland adopts PTI-PN test for DPF inspections

4 March 2022

Swiss Federal Department of the Environment, Transport, Energy and Communications (DETEC; German: UVEK) has adopted a new, particle number (PN) based test for periodic technical inspections (PTI) of diesel vehicles equipped with diesel particulate filters (DPF).

The new PTI testing requirements come into effect on 1 January 2023. They have been published as amendments to the regulation on maintenance and follow-up inspections of motor vehicles.

The PN limit values are 2.5×105 #/cm3 at high idle and no load, or 1×105 #/cm3 at low idle condition. The measurement must be conducted using a particle counter approved under Swiss Regulation SR 941.242. The regulation, adopted in 2012, was originally developed for PN testers for nonroad mobile machinery in Switzerland.

The PTI-PN test involves the use of a particle counting instrument to detect particulate filter removal/tampering or other DPF malfunctions. The new test will replace older PTI methods based on smoke measurement that are not sensitive enough for modern diesel engines.

Switzerland is the fourth country to officially adopt PTI-PN testing requirements, after the Netherlands, Belgium, and Germany.

The initiative to develop and introduce PN tests for DPF checks during PTI inspections, known as new PTI (NPTI), was launched by VERT in 2016, and the PTI-PN test was developed at TNO [4763][4767].

Gerrit Kadijk, who was at the time a key TNO researcher working on the NPTI project, has written a book that covers PTI-PN testing and the related technical background in great detail. The book, titled Particles Matter, is now also available in English translation [5419].

Source: Bundesamt für Strassen (ASTRA)