Document ID: chunk:federal_register_of_legislation:F2024L00446:reg:16:p73
Version: federal_register_of_legislation:F2024L00446
Segment Type: reg
Provision Reference: reg 16 (pt 73/108)
Character Range: 1095058–1098046

to be zero.
              2.1.3.2.2. The dilution air background particle number level shall be determined by sampling filtered dilution air. This shall be drawn from a point immediately downstream of the dilution air filters into the PN measurement system. Background levels in particles per cm³ shall be determined as a rolling arithmetic average of least 14 measurements with at least one measurement per week.
              2.1.3.2.3. The dilution tunnel background particle number level shall be determined by sampling filtered dilution air. This shall be drawn from the same point as the PN sample. Where secondary dilution is used for the test the secondary dilution system shall be active for the purposes of background measurement. One measurement may be performed on the day of test, either prior to or after the test using the actual PCRF and the CVS flow rate utilised during the test.
              2.2. General test cell equipment
              2.2.1. Parameters to be measured
              2.2.1.1. The following temperatures shall be measured with an accuracy of ±1.5 °C:
              (a) Test cell ambient air;
                  (b) Dilution and sampling system temperatures as required for emissions measurement systems defined in Annex B5.
              2.2.1.2. Atmospheric pressure shall be measurable with a precision of ±0.1 kPa.
              2.2.1.3. Specific humidity H shall be measurable with a precision of ±1 g H2O/kg dry air.
              2.2.2. Test cell and soak area
              2.2.2.1. Test cell
              2.2.2.1.1. The test cell shall have a temperature set point of 23 °C. The tolerance of the actual value shall be within ±5 °C. The air temperature and humidity shall be measured at the test cell's cooling fan outlet at a minimum frequency of 0.1 Hz. For the temperature at the start of the test, see paragraph 2.8.1. of this annex.
              2.2.2.1.2. The specific humidity H of either the air in the test cell or the intake air of the engine shall be such that:
               (g H2O/kg dry air)
              2.2.2.1.3. Humidity shall be measured continuously at a minimum frequency of 0.1 Hz.
              2.2.2.2. Soak area
              The soak area shall have a temperature set point of 23 °C and the tolerance of the actual value shall be within ±3 °C on a 5-minute running arithmetic average and shall not show a systematic deviation from the set point. The temperature shall be measured continuously at a minimum frequency of 0.033 Hz (every 30 s).
              2.3. Test vehicle
              2.3.1. General
              The test vehicle shall conform in all its components with the production series, or, if the vehicle is different from the production series (e.g. for worst case testing), a full description shall be recorded. In selecting the test vehicle, the manufacturer and the responsible authority shall agree which vehicle model is representative for the interpolation family.
              In the case that