Document ID: chunk:federal_register_of_legislation:F2012C00283:reg:21:p28
Version: federal_register_of_legislation:F2012C00283
Segment Type: reg
Provision Reference: reg 21 (pt 28/39)
Character Range: 334047–336984

following properties:
               It shall have an internal diameter of ≥ 4 mm;
               Sample Gas flow through the POT shall have a residence time of ≤ 0.8 seconds.
               Any other sampling configuration for the OT for which equivalent particle penetration for particles of 30 nm electrical mobility diameter can be demonstrated will be considered acceptable.
              1.4.3. Particle Pre-classifier
               The recommended particle pre-classifier shall be located upstream of the VPR. The pre-classifier 50 per cent cut point particle diameter shall be between 2.5 µm and 10 µm at the volumetric flow rate selected for sampling particle number emissions. The pre-classifier shall allow at least 99 per cent of the mass concentration of 1 µm particles entering the pre-classifier to pass through the exit of the pre-classifier at the volumetric flow rate selected for sampling particle number emissions.
              1.4.4. Volatile Particle Remover (VPR)
               The VPR shall comprise one particle number diluter (PND1), an evaporation tube and a second diluter (PND2) in series. This dilution function is to reduce the number concentration of the sample entering the particle concentration measurement unit to less than the upper threshold of the single particle count mode of the PNC and to suppress nucleation within the sample. The VPR shall provide an indication of whether or not PND1 and the evaporation tube are at their correct operating temperatures.
               The VPR shall achieve > 99.0 per cent vaporisation of 30 nm tetracontane (CH3(CH2)38CH3) particles, with an inlet concentration of ≥ 10,000 cm-3, by means of heating and reduction of partial pressures of the tetracontane. It shall also achieve a particle concentration reduction factor (fr) 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 per cent lower than that for particles of 100 nm electrical mobility diameter for the VPR as a whole.
              1.4.4.1. First Particle Number Dilution Device (PND1)
               The first particle number dilution device shall be specifically designed to dilute particle number concentration and operate at a (wall) temperature of 150 °C ‑ 400 °C. The wall temperature setpoint should be held at a constant nominal operating temperature, within this range, to a tolerance of ±10 °C and not exceed the wall temperature of the ET (paragraph 1.4.4.2.). The diluter should be supplied with HEPA filtered dilution air and be capable of a dilution factor of 10 to 200 times.
              1.4.4.2. Evaporation Tube
               The entire length of the ET shall be controlled to a wall temperature greater than or equal to that of the first particle number dilution device and the wall temperature held at a fixed nominal operating temperature between 300 °C and 400 °C, to