Document ID: chunk:federal_register_of_legislation:F2023L00129:reg:13:p4
Version: federal_register_of_legislation:F2023L00129
Segment Type: reg
Provision Reference: reg 13 (pt 4/27)
Character Range: 560067–563080

equipment
A.8.1. Specification
              A.8.1.1. System overview
              A.8.1.1.1. The particle sampling system shall consist of a probe or sampling point extracting a sample from a homogenously mixed flow in a dilution system as described in Appendix 2 to this annex, paragraph A.2.2.1. and A.2.2.2. or A.2.2.3. and A.2.2.4., a volatile particle remover (VPR) upstream of a particle number counter (PNC) and suitable transfer tubing.
              A.8.1.1.2. It is recommended that a particle size pre-classifier (e.g. cyclone, impactor, etc.) be located prior to the inlet of the VPR. However, a sample probe acting as an appropriate size-classification device, such as that shown in Appendix 2 to this annex, Figure 14, is an acceptable alternative to the use of a particle size pre-classifier. In the case of partial flow dilution systems it is acceptable to use the same pre-classifier for particulate mass and particle number sampling, extracting the particle number sample from the dilution system downstream of the pre-classifier. Alternatively separate pre-classifiers may be used, extracting the particle number sample from the dilution system upstream of the particulate mass pre-classifier.
A.8.1.2. General requirements
              A.8.1.2.1. The particle sampling point shall be located within a dilution 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 of the VPR. 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 its axis at the tip parallel to that of the dilution tunnel. The sampling probe shall be positioned within the dilution tract so that the sample is taken from a homogeneous diluent/exhaust mixture.
               In the case of partial flow dilution systems of the total sampling type (as described in Appendix 2 to this annex, paragraph A.2.2.1.) the particle sampling point or sampling probe shall be located in the particulate transfer tube, upstream of the particulate filter holder, flow measurement device and any sample/bypass bifurcation point. The sampling point or sampling probe shall be positioned so that the sample is taken from a homogeneous diluent/exhaust mixture. The dimensions of the particle sampling probe should be sized not to interfere with the operation of the partial flow dilution system.
               Sample gas drawn through the PTS shall meet the following conditions:
               In the case of full flow dilution systems, it shall have a flow Reynolds number (Re) of < 1,700;
               In the case