Document ID: chunk:federal_register_of_legislation:F2024L00446:reg:16:p64
Version: federal_register_of_legislation:F2024L00446
Segment Type: reg
Provision Reference: reg 16 (pt 64/108)
Character Range: 1067024–1070298

electrical mobility diameters shall be within ±10 per cent of the arithmetic average particle concentration reduction factor determined during the latest complete calibration of the VPR.
              5.7.2.2. The test aerosol for these measurements shall be solid particles of 30, 50 and 100 nm electrical mobility diameter and a minimum concentration of 5,000 particles per cm³ at the VPR inlet. As an option, a polydisperse aerosol with an electrical mobility median diameter of 50 nm may be used for validation. The test aerosol shall be thermally stable at the VPR operating temperatures. Particle number concentrations shall be measured upstream and downstream of the components.
              The particle concentration reduction factor for each monodisperse particle size, fr(di), shall be calculated using the following equation:
              where:
                     Nin(di) is the upstream particle number concentration for particles of diameter di;
                     Nout(di) is the downstream particle number concentration for particles of diameter di;
              di is the particle electrical mobility diameter (30, 50 or 100 nm).
              Nin(di) and Nout(di) shall be corrected to the same conditions.
              The arithmetic average particle concentration reduction factor  at a given dilution setting shall be calculated using the following equation:
              Where a polydisperse 50 nm aerosol is used for validation, the arithmetic average particle concentration reduction factor  at the dilution setting used for validation shall be calculated using the following equation:
              where:
              Nin is the upstream particle number concentration;
              Nout is the downstream particle number concentration.
              5.7.2.3. The VPR shall demonstrate greater than 99.0 per cent removal of tetracontane (CH3(CH2)38CH3) particles of at least 30 nm electrical mobility diameter with an inlet concentration ≥ 10,000 per cm³ when operated at its minimum dilution setting and manufacturer's recommended operating temperature.
              5.7.2.4. The instrument manufacturer shall provide the maintenance or replacement interval that ensures that the removal efficiency of the VPR does not drop below the technical requirements. If such information is not provided, the volatile removal efficiency shall be checked yearly for each instrument.

              5.7.2.5. The instrument manufacturer shall prove the solid particle penetration Pr(di) by testing one unit for each PN-system model. A PN-system model here covers all PN-systems with the same hardware, i.e. same geometry, conduit materials, flows and temperature profiles in the aerosol path. Pr(di) at a particle size, di, shall be calculated using the equation specified in paragraph 4.3.1.3.3.1.

              5.7.3. PN measurement system check procedures
              On a monthly basis, the flow into the PNC shall have a measured value within 5 per cent of the PNC nominal flow rate when checked with a calibrated flow meter. Here the term 'nominal flow rate' refers to the flow rate stated in the last calibration for the PNC by the instrument manufacturer.
              5.8. Accuracy of the mixing device
              In the case that a