Document ID: chunk:federal_register_of_legislation:F2023L00129:reg:13:p47
Version: federal_register_of_legislation:F2023L00129
Segment Type: reg
Provision Reference: reg 13 (pt 47/56)
Character Range: 423329–425956

least five values corresponding to dilution ratios between 3 and 50. Alternatively, a special calibration flow path may be provided, in which the tunnel is bypassed, but the total and diluent flow through the corresponding meters as in the actual test;
(d) A tracer gas shall be fed into the exhaust transfer tube TT. This tracer gas may be a component of the exhaust gas, like CO2 or NOx. After dilution in the tunnel the tracer gas component shall be measured. This shall be carried out for five dilution ratios between 3 and 50. The accuracy of the sample flow shall be determined from the dilution ratio rd:
  qmp = qmdew /rd (84)
The accuracies of the gas analyzers shall be taken into account to guarantee the accuracy of qmp.
9.4.6.4. Carbon flow check
 A carbon flow check using actual exhaust is strongly recommended for detecting measurement and control problems and verifying the proper operation of the partial flow system. The carbon flow check should be run at least each time a new engine is installed, or something significant is changed in the test cell configuration.
 The engine shall be operated at peak torque load and speed or any other steady state mode that produces 5 per cent or more of CO2. The partial flow sampling system shall be operated with a dilution factor of about 15 to 1.
 If a carbon flow check is conducted, the procedure given in Appendix 4 shall be applied. The carbon flow rates shall be calculated according to equations 112 to 114 in Appendix 4 to this annex. All carbon flow rates should agree to within 3 per cent.
9.4.6.5. Pre-test check
 A pre-test check shall be performed within 2 hours before the test run in the following way.
 The accuracy of the flowmeters shall be checked by the same method as used for calibration (see paragraph 9.4.6.2.) for at least two points, including flow values of qmdw that correspond to dilution ratios between 5 and 15 for the qmdew value used during the test.
 If it can be demonstrated by records of the calibration procedure under paragraph 9.4.6.2. that the flowmeter calibration is stable over a longer period of time, the pre-test check may be omitted.
9.4.6.6. Determination of the transformation time
 The system settings for the transformation time evaluation shall be exactly the same as during measurement of the test run. The transformation time shall be determined by the following method.
 An independent reference flowmeter with a measurement range appropriate for the probe flow shall be put in series with and closely coupled to the probe. This flowmeter shall have a transformation time of less than 100 ms for the flow step