Document ID: chunk:federal_register_of_legislation:F2024L00447:reg:0:p32
Version: federal_register_of_legislation:F2024L00447
Segment Type: reg
Provision Reference: reg 0 (pt 32/57)
Character Range: 179817–182985

15 per cent of their mean value. At least 5 points equally distributed (plus the zero) shall be checked. The maximum checked concentration shall be > 90 per cent of the PN analyser nominal measurement range.

              If the PN analyser is calibrated in parts, then the linearity can be checked only for the PN detector, but the efficiencies of the rest parts and the sampling line shall be considered in the slope calculation.

              6.4. Volatile removal efficiency

              The system shall achieve > 99 per cent removal of ≥ 30 nm tetracontane (CH3(CH2)38CH3) particles with an inlet concentration of ≥ 10000 particles per cubic-centimetre at the minimum dilution.

              The system shall also achieve a > 99 per cent removal efficiency of tetracontane with count median diameter > 50 nm and mass > 1 mg/m3.

              The volatile removal efficiency with tetracontane shall be proven only once for the instrument family. The instrument manufacturer though shall provide the maintenance or replacement interval that ensures that the removal efficiency does not drop below the technical requirements. If such information is not provided, the volatile removal efficiency shall be checked yearly for each instrument.

              7. Instruments for measuring exhaust mass flow

              7.1. General

              Instruments or signals for measuring the exhaust mass flow rate shall have a measuring range and response time appropriate for the accuracy required to measure the exhaust mass flow rate under transient and steady state conditions. The sensitivity of instruments and signals to shocks, vibration, aging, variability in temperature, ambient air pressure, electromagnetic interferences and other impacts related to vehicle and instrument operation shall be on a level as to eliminate additional errors.

              7.2. Instrument specifications

              The exhaust mass flow rate shall be determined by a direct measurement method applied in either of the following instruments:

               (a) Pitot-based flow devices;

               (b) Pressure differential devices like flow nozzle (details see ISO 5167);

               (c) Ultrasonic flow meter;

               (d) Vortex flow meter.

              Each individual exhaust mass flow meter shall fulfil the linearity requirements set out in paragraph 3. Furthermore, the instrument manufacturer shall demonstrate the compliance of each type of exhaust mass flow meter with the specifications in paragraphs 7.2.3. to 7.2.9.

              It is permissible to calculate the exhaust mass flow rate based on air flow and fuel flow measurements obtained from sensors with traceable calibration if these fulfil the linearity requirements of paragraph 3., the accuracy requirements of paragraph 8. and if the resulting exhaust mass flow rate is validated according to paragraph 4. of Annex 6.

              In addition, other methods that determine the exhaust mass flow rate based on non-traceable instruments and signals, such as simplified exhaust mass flow meters or ECU signals, are permissible if the resulting exhaust mass flow rate fulfils