Document ID: chunk:federal_register_of_legislation:F2023L00129:reg:13:p9
Version: federal_register_of_legislation:F2023L00129
Segment Type: reg
Provision Reference: reg 13 (pt 9/27)
Character Range: 573854–576807

upstream of the particulate mass pre-classifier.
              A.8.1.4.4. 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.
              A.8.1.4.4.1. 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 to 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 A.8.1.4.4.2.). The diluter should be supplied with HEPA filtered dilution air and be capable of a dilution factor of 10 to 200 times.
              A.8.1.4.4.2. Evaporation Tube (ET)
               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 a tolerance of ±10 °C.
              A.8.1.4.4.3. Second particle number dilution device (PND2)
               PND2 shall be specifically designed to dilute particle number concentration. The diluter shall be supplied with HEPA filtered dilution air and be capable of maintaining a single dilution factor within a range of 10 to 30 times. The dilution factor of PND2 shall be selected in the range between 10 and 15 such that particle number concentration downstream of the second diluter is less than the upper threshold of the single particle count mode of the PNC and the gas temperature prior to entry to the PNC is < 35 °C.
              A.8.1.4.5. Particle number counter (PNC)
               The PNC shall meet the requirements of paragraph A.8.1.3.4.
              A.8.2. Calibration/Validation of the particle sampling system[28]
              A.8.2.1. Calibration of the