Document ID: chunk:federal_register_of_legislation:F2024C00356:reg:21:p24
Version: federal_register_of_legislation:F2024C00356
Segment Type: reg
Provision Reference: reg 21 (pt 24/35)
Character Range: 354001–356937

30 days.
               Multiple reconditioning and reweighings of the sample and reference filters are permitted until a period of 80 h has elapsed following the measurement of gases from the emissions test.
               If, prior to or at the 80 h point, more than half the number of reference filters meet the ±5 µg criterion, then the sample filter weighing can be considered valid.
               If, at the 80 h point, two reference filters are employed and one filter fails the ±5 µg criterion, the sample filter weighing can be considered valid under the condition that the sum of the absolute differences between specific and rolling averages from the two reference filters must be less than or equal to 10 µg.
               In case less than half of the reference filters meet the ±5 µg criterion the sample filter shall be discarded, and the emissions test repeated. All reference filters must be discarded and replaced within 48 hours.
               In all other cases, reference filters must be replaced at least every 30 days and in such a manner that no sample filter is weighed without comparison to a reference filter that has been present in the weighing room for at least 1 day.
               If the weighing room stability criteria outlined in paragraph 1.3.4. are not met, but the reference filter weighings meet the above criteria, the vehicle manufacturer has the option of accepting the sample filter weights or voiding the tests, fixing the weighing room control system and re-running the test.

Figure 13
Particulate sampling probe configuration

Annexe 4a -Appendix 5
  Particle number emissions measurement equipment
              1. Specification
              1.1. System Overview
              1.1.1. The particle sampling system shall consist of a dilution tunnel, a sampling probe and a volatile particle remover (VPR) upstream of a particle number counter (PNC) and suitable transfer tubing.
              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 Figure 13, is an acceptable alternative to the use of a particle size pre-classifier.
              1.2. General Requirements
              1.2.1. The particle sampling point shall be located within a dilution tunnel.
               The sampling probe tip (PSP) 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:
               It 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.
               It shall have an internal diameter of ≥ 8