Document ID: chunk:federal_register_of_legislation:F2024L00446:reg:16:p56
Version: federal_register_of_legislation:F2024L00446
Segment Type: reg
Provision Reference: reg 16 (pt 56/108)
Character Range: 1041956–1045003

that a double dilution system is used, it shall have a flow Reynolds number Re lower than 1,700 in the PTT i.e. downstream of the sampling probe or point;
                  (c) Shall have a residence time ≤ 3 seconds.
              4.3.1.2.1.3. Any other sampling configuration for the PTS for which equivalent solid particle penetration at 30 nm can be demonstrated shall be considered acceptable.
              4.3.1.2.1.4. The outlet tube (OT), conducting the diluted sample from the VPR to the inlet of the PNC, shall have the following properties:
              (a) An internal diameter ≥ 4mm;
              (b) A sample gas flow residence time of ≤ 0.8 seconds.
              4.3.1.2.1.5. Any other sampling configuration for the OT for which equivalent solid particle penetration at 30 nm can be demonstrated shall be considered acceptable.
              4.3.1.2.2. The VPR shall include devices for sample dilution and for volatile particle removal.
              4.3.1.2.3. All parts of the dilution system and the sampling system from the exhaust pipe up to the PNC, which are in contact with raw and diluted exhaust gas, shall be made of electrically conductive materials, shall be electrically grounded to prevent electrostatic effects and shall be designed to minimize deposition of the particles.
              4.3.1.2.4. The particle sampling system shall incorporate good aerosol sampling practice that includes the avoidance of sharp bends and abrupt changes in cross-section, the use of smooth internal surfaces and the minimization of the length of the sampling line. Gradual changes in the cross-section are permitted.
              4.3.1.3. Specific requirements
              4.3.1.3.1. The particle sample shall not pass through a pump before passing through the PNC.
              4.3.1.3.2. A sample pre-classifier is recommended.
              4.3.1.3.3. The VPR shall:
                  (a) Be capable of diluting the sample in one or more stages to achieve a particle number concentration below the upper threshold of the single particle count mode of the PNC;
                  (b) Have a gas temperature at the inlet to the PNC below the maximum allowed inlet temperature specified by the PNC manufacturer;
                  (c)  Include an initial heated dilution stage that outputs a sample at a temperature of  150 °C and ≤ 350 °C ±10 °C, and dilutes by a factor of at least 10;
                  (d) Control heated stages to constant nominal operating temperatures, within the range ≥ 150 °C and ≤ 400 °C ±10 °C;
                  (e) Provide an indication of whether or not heated stages are at their correct operating temperatures;
                  (f) Achieve a solid particle penetration efficiency of at least 70 per cent for particles of 100 nm electrical mobility diameter;
                  (g) Achieve a particle concentration reduction factor fr(di) for particles of 30 nm and 50 nm electrical mobility diameters that is no more than 30 per cent and 20 per cent respectively higher, and no more than 5