Document ID: chunk:federal_register_of_legislation:F2023L00129:reg:13:p52
Version: federal_register_of_legislation:F2023L00129
Segment Type: reg
Provision Reference: reg 13 (pt 52/56)
Character Range: 435891–439024

A.2.2.2. or a full flow dilution system as described in Appendix 2 to this annex, paragraph A.2.2.3. and A.2.2.4.
              10.1.1. Diluent filtration
               Diluent used for both the primary and, where applicable, secondary dilution of the exhaust in the dilution system shall be passed through filters meeting the High-Efficiency Particulate Air (HEPA) filter requirements defined in Appendix 2 to this annex, paragraphs A.2.2.2. or A.2.2.4. The diluent may optionally be charcoal scrubbed before being passed to the HEPA filter to reduce and stabilize the hydrocarbon concentrations in the diluent. It is recommended that an additional coarse particle filter is situated before the HEPA filter and after the charcoal scrubber, if used.
              10.2. Compensating for particle number sample flow – full flow dilution systems
               To compensate for the mass flow extracted from the dilution system for particle number sampling the extracted mass flow (filtered) shall be returned to the dilution system. Alternatively, the total mass flow in the dilution system may be mathematically corrected for the particle number sample flow extracted. Where the total mass flow extracted from the dilution system for the sum of particle number sampling and particulate mass sampling is less than 0.5 per cent of the total dilute exhaust gas flow in the dilution tunnel (med) this correction, or flow return, may be neglected.
              10.3. Compensating for particle number sample flow – partial flow dilution systems
              10.3.1. For partial flow dilution systems the mass flow extracted from the dilution system for particle number sampling shall be accounted for in controlling the proportionality of sampling. This shall be achieved either by feeding the particle number sample flow back into the dilution system upstream of the flow measuring device or by mathematical correction as outlined in paragraph 10.3.2. In the case of total sampling type partial flow dilution systems, the mass flow extracted for particle number sampling shall also be corrected for in the particulate mass calculation as outlined in paragraph 10.3.3.
              10.3.2. The instantaneous exhaust gas flow rate into the dilution system (qmp), used for controlling the proportionality of sampling, shall be corrected according to one of the following methods:
                   (a) In the case where the extracted particle number sample flow is discarded, equation 83 in paragraph 9.4.6.2. shall be replaced by the following:
                             (92)
                 Where:
                          qmp = sample flow of exhaust gas into partial flow dilution system, kg/s,
                          qmdew = diluted exhaust mass flow rate, kg/s,
                          qmdw = dilution air mass flow rate, kg/s,
                          qex = particle number sample mass flow rate, kg/s.
                    The qex signal sent to the partial flow system controller shall be accurate to within 0.1 per cent of qmdew at all times and should be sent with frequency of at least 1 Hz.
                   (b)