This explanatory note by IWG PMP, updates on the proposals for solid particle number (SPN) measurements for the type approval of heavy-duty engines. The explanatory note addresses (i) the changes to the current SPN23 methodology, (ii) the proposed changes for the second alternative option to extend the particle size detection range to 10 nm particles, (iii) the proposed changes to allow direct SPN sampling with fixed dilution ratio.

This proposal from IWG PMP is based on the PN measurement procedure laid down in UN R49 but should be considered exclusively a technical working document. The purpose of this document is only to discuss within the PMP group the changes/additions needed to modify the PN cut-off size from 23 to approximately 10 nm and to include raw exhaust sampling

Status report from IWG PMP