Document ID: chunk:federal_register_of_legislation:F2024L00447:reg:0:p11
Version: federal_register_of_legislation:F2024L00447
Segment Type: reg
Provision Reference: reg 0 (pt 11/57)
Character Range: 122272–125221

measurement device not part of the vehicle shall be installed to measure the parameter under consideration in a representative, reliable and accurate manner without unduly interfering with the vehicle operation and the functioning of other analysers, flow-measuring instruments, sensors and signals. Sensors and auxiliary equipment shall be powered independently of the vehicle. It is permitted to power any safety-related illumination of fixtures and installations of PEMS components outside of the vehicle's cabin by the vehicle's battery.

              3.5. Emissions sampling

              Emissions sampling shall be representative and conducted at locations of well-mixed exhaust, where the influence of ambient air downstream of the sampling point is minimal. If applicable, emissions shall be sampled downstream of the exhaust mass flow meter, respecting a distance of at least 150 mm to the flow sensing element. The sampling probes shall be fitted at least 200 mm or three times the inner diameter of the exhaust pipe, whichever is larger, upstream of the point at which the exhaust gas exits the PEMS sampling installation into the environment.

              If the PEMS feeds part of the sample back to the exhaust flow, this shall occur downstream of the sampling probe in a manner that does not affect the nature of the exhaust gas at the sampling point(s). If the length of the sampling line is changed, the system transport times shall be verified and, if necessary, corrected. If the vehicle is equipped with more than one tailpipe then all functioning tailpipes shall be connected before sampling and measuring exhaust flow.

              If the engine is equipped with an exhaust after-treatment system, the exhaust sample shall be taken downstream of the exhaust after-treatment system. When testing a vehicle with a branched exhaust manifold, the inlet of the sampling probe shall be located sufficiently far downstream so as to ensure that the sample is representative of the average exhaust emissions of all cylinders. In multi-cylinder engines, having distinct groups of manifolds, such as in a 'V' engine configuration, the sampling probe shall be positioned downstream of where the manifolds combine. If this is technically not feasible, multi-point sampling at locations of well-mixed exhaust may be used. In this case, the number and location of sampling probes shall match as far as possible those of the exhaust mass flow meters. In case of unequal exhaust flows, proportional sampling or sampling with multiple analysers shall be considered.

              If particles are measured, they shall be sampled from the centre of the exhaust stream. If several probes are used for emissions sampling, the particle sampling probe should be placed upstream of the other sampling probes. The particle sampling probe should not interfere with the sampling of gaseous pollutants. The type and specifications of the probe and