Document ID: chunk:federal_register_of_legislation:F2023L00129:reg:13:p41
Version: federal_register_of_legislation:F2023L00129
Segment Type: reg
Provision Reference: reg 13 (pt 41/56)
Character Range: 407918–410899

the average exhaust emissions from all cylinders. In multi-cylinder engines having distinct groups of manifolds, such as in a "Vee" engine configuration, it is recommended to combine the manifolds upstream of the sampling probe. If this is not practical, it is permissible to acquire a sample from the group with the highest CO2 emission. For exhaust emission calculation the total exhaust mass flow shall be used.
 If the engine is equipped with an exhaust after-treatment system, the exhaust sample shall be taken downstream of the exhaust after-treatment system.
9.3.11. Sampling for dilute gaseous emissions, if applicable
 The exhaust pipe between the engine and the full flow dilution system shall conform to the requirements laid down in Appendix 2 to this annex. The gaseous emissions sample probe(s) shall be installed in the dilution tunnel at a point where the diluent and exhaust gas are well mixed, and in close proximity to the particulates sampling probe.
 Sampling can generally be done in two ways:
(a) The emissions are sampled into a sampling bag over the cycle and measured after completion of the test; for HC, the sample bag shall be heated to 464  11 K (191  11°C), for NOx, the sample bag temperature shall be above the dew point temperature;
(b) The emissions are sampled continuously and integrated over the cycle.
 The background concentration shall be determined upstream of the dilution tunnel according to (a) or (b), and shall be subtracted from the emissions concentration according to paragraph 8.5.2.3.2.
9.4. Particulate measurement and sampling system
9.4.1. General specifications
 To determine the mass of the particulates, a particulate dilution and sampling system, a particulate sampling filter, a microgram balance, and a temperature and humidity controlled weighing chamber, are required. The particulate sampling system shall be designed to ensure a representative sample of the particulates proportional to the exhaust flow.
              9.4.2. General requirements of the dilution system

               The determination of the particulates requires dilution of the sample with filtered ambient air, synthetic air or nitrogen (the diluent). The dilution system shall be set as follows:

                  (a)            Completely eliminate water condensation in the dilution and sampling systems;

                  (b)           Maintain the temperature of the diluted exhaust gas between 315 K (42 °C) and 325 K (52 °C) within 20 cm upstream or downstream of the filter holder(s);

                  (c)            The diluent temperature shall be between 293 K and 325 K (20 °C to 52 °C) in close proximity to the entrance into the dilution tunnel;

                  (d)           The minimum dilution ratio shall be within the range of 5:1 to 7:1 and at least 2:1 for the primary dilution stage based on the maximum engine exhaust flow rate;

                  (e)            For a partial flow dilution system, the residence