Document ID: chunk:federal_register_of_legislation:F2023L00129:reg:13:p5
Version: federal_register_of_legislation:F2023L00129
Segment Type: reg
Provision Reference: reg 13 (pt 5/27)
Character Range: 562810–565872

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 of partial flow dilution systems, it shall have a flow Reynolds number (Re) of < 1,700 in the PTT i.e. downstream of the sampling probe or point;
               It shall have a residence time in the PTS of ≤ 3 seconds.
               Any other sampling configuration for the PTS for which equivalent particle penetration at 30 nm can be demonstrated will be considered acceptable.
               The outlet tube (OT) conducting the diluted sample from the VPR to the inlet of the PNC shall have the following properties:
               It shall have an internal diameter of ≥ 4 mm;
               Sample Gas flow through the OT shall have a residence time of ≤ 0.8 second.
               Any other sampling configuration for the OT for which equivalent particle penetration at 30 nm can be demonstrated will be considered acceptable.
              A.8.1.2.2. The VPR shall include devices for sample dilution and for volatile particle removal.
              A.8.1.2.3. 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 designed to minimize deposition of the particles. All parts shall be made of electrically conductive materials that do not react with exhaust gas components, and shall be electrically grounded to prevent electrostatic effects.
              A.8.1.2.4. The particle sampling system shall incorporate good aerosol sampling practice that includes the avoidance of sharp bends and abrupt changes in cross-paragraph, the use of smooth internal surfaces and the minimisation of the length of the sampling line. Gradual changes in the cross-section are permissible.
              A.8.1.3. Specific requirements
              A.8.1.3.1. The particle sample shall not pass through a pump before passing through the PNC.
              A.8.1.3.2. A sample pre-classifier is recommended.
              A.8.1.3.3. The sample preconditioning unit shall:
              A.8.1.3.3.1. 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 and a gas temperature below 35 °C at the inlet to the PNC;
              A.8.1.3.3.2. Include an initial heated dilution stage which outputs a sample at a temperature of   150 °C and ≤ 400 °C, and dilutes by a factor of at least 10;
              A.8.1.3.3.3. Control heated stages to constant nominal operating temperatures, within the range specified in paragraph A.8.1.3.3.2., to a tolerance of ±10 °C. Provide an indication of whether or not heated stages are at their correct operating temperatures;
              A.8.1.3.3.4. Achieve a particle concentration reduction factor (fr(di)), as defined in paragraph A.8.2.2.2.