Document ID: chunk:federal_register_of_legislation:F2023L00129:reg:13:p7
Version: federal_register_of_legislation:F2023L00129
Segment Type: reg
Provision Reference: reg 13 (pt 7/27)
Character Range: 568305–571343

be measured and reported for the purposes of correcting particle concentration measurements to standard conditions.
              A.8.1.3.6. The sum of the residence time of the PTS, VPR and OT plus the t90 response time of the PNC shall be no greater than 20 s.
              A.8.1.3.7. The transformation time of the entire particle number sampling system (PTS, VPR, OT and PNC) shall be determined by aerosol switching directly at the inlet of the PTS. The aerosol switching shall be done in less than 0.1 s. The aerosol used for the test shall cause a concentration change of at least 60 per cent full scale (FS).
               The concentration trace shall be recorded. For time alignment of the particle number concentration and exhaust flow signals, the transformation time is defined as the time from the change (t0) until the response is 50 per cent of the final reading (t50).
              A.8.1.4. Recommended system description
               The following paragraph contains the recommended practice for measurement of particle number. However, any system meeting the performance specifications in paragraphs A.8.1.2. and A.8.1.3. is acceptable.
               Figures 19 and 20 are schematic drawings of the recommended particle sampling system configures for partial and full flow dilution systems respectively.
       Figure 19
       Schematic of recommended particle sampling system – Partial flow sampling
       Figure 20
       Schematic of recommended particle sampling system – Full flow sampling
              A.8.1.4.1. Sampling system description
               The particle sampling system shall consist of a sampling probe tip or particle sampling point in the dilution system, a particle transfer tube (PTT), a particle pre-classifier (PCF) and a volatile particle remover (VPR) upstream of the particle number concentration measurement (PNC) unit. The VPR shall include devices for sample dilution (particle number diluters: PND1 and PND2) and particle evaporation (Evaporation tube, ET). The sampling probe or sampling point for the test gas flow shall be so arranged within the dilution tract that a representative sample gas flow is taken from a homogeneous diluent/exhaust mixture. The sum of the residence time of the system plus the t90 response time of the PNC shall be no greater than 20 s.
              A.8.1.4.2. Particle transfer system
               The sampling probe tip or particle sampling point and Particle Transfer Tube (PTT) together comprise the Particle Transfer System (PTS). The PTS conducts the sample from the dilution tunnel to the entrance to the first particle number diluter. The PTS shall meet the following conditions:
               In the case of full flow dilution systems and partial flow dilution systems of the fractional sampling type (as described in Appendix 2 to this annex, paragraph A.2.2.1.) the sampling probe shall be installed near the tunnel centre line, 10 to 20 tunnel diameters downstream of the gas inlet, facing upstream into the tunnel gas flow with