Document ID: chunk:federal_register_of_legislation:F2011C00805:reg:20:p14
Version: federal_register_of_legislation:F2011C00805
Segment Type: reg
Provision Reference: reg 20 (pt 14/23)
Character Range: 181844–184788

of the roller (the front roller in the case of a two-roller dynamometer).

           4.1.5.   Load and inertia setting

           4.1.5.1.   Dynamometer with fixed load curve: the load simulator shall be adjusted to absorb the power exerted on the driving wheels at a steady speed of 80 km/h and the absorbed power at 50 km/h shall be noted. The means by which this load is determined and set are described in Appendix 3 to this Annex.

           4.1.5.2.   Dynamometer with adjustable load curve: the load simulator shall be adjusted in order to absorb the power exerted on the driving wheels at steady speeds of 120, 100, 80, 60 and 40 and 20 km/h. The means by which these loads are determined and set are described in Appendix 3 to this Annex.

           4.1.5.3.   Inertia

           Dynamometers with electric inertia simulation shall be demonstrated to be equivalent to mechanical inertia systems. The means by which equivalence is established are described in Appendix 4 to this Annex.

           4.2.   Exhaust gas-sampling system

           4.2.1.   The exhaust gas sampling system shall be able to measure the actual quantities of pollutants emitted in the exhaust gases to be measured. The system that shall be used is the constant volume sampler (CVS) system. This requires that the vehicle exhaust be continuously diluted with ambient air under controlled conditions. In the constant volume sampler concept of measuring mass emissions, two conditions shall be satisfied, the total volume of the mixture of exhaust and dilution air shall be measured and a continuously proportional sample of the volume shall be collected for analysis. The quantities of pollutants are determined from the sample concentrations, corrected for the pollutant content of the ambient air and the totalised flow over the test period.

           The particulate pollutant emission level is determined by using suitable filters to collect the particulates from a proportional part flow throughout the test and determining the quantity thereof gravimetrically in accordance with paragraph 4.3.1.1.

           4.2.2.   The flow through the system shall be sufficient to eliminate water condensation at all conditions which may occur during a test, as defined in Appendix 5 to this Annex.

           4.2.3.  Appendix 5 gives examples of three types of constant volume sampler system which satisfy the requirements of this Annex.

           4.2.4.  The gas and air mixture shall be homogeneous at point S2 of the sampling probe.

           4.2.5.   The probe shall extract a true sample of the diluted exhaust gases.

           4.2.6.   The system shall be free of gas leaks. The design and materials shall be such that the system does not influence the pollutant concentration in the diluted exhaust gas. Should any component (heat exchanger, blower, etc.) change the concentration of any pollutant gas in the diluted gas, the sampling for that