Document ID: chunk:federal_register_of_legislation:F2024L00446:reg:16:p35
Version: federal_register_of_legislation:F2024L00446
Segment Type: reg
Provision Reference: reg 16 (pt 35/108)
Character Range: 983091–985944

components, and shall be electrically grounded to prevent electrostatic effects.
              3.2.6. If the vehicle being tested is equipped with an exhaust pipe comprising several branches, the connecting tubes shall be connected as near as possible to the vehicle without adversely affecting their operation.
              3.3. Specific requirements
              3.3.1. Connection to vehicle exhaust
              3.3.1.1. The start of the connecting tube is the exit of the tailpipe. The end of the connecting tube is the sample point, or first point of dilution.
              For multiple tailpipe configurations where all the tailpipes are combined, the start of the connecting tube shall be taken at the last joint of where all the tailpipes are combined. In this case, the tube between the exit of the tailpipe and the start of the connecting tube may or may not be insulated or heated.
              3.3.1.2. The connecting tube between the vehicle and dilution system shall be designed so as to minimize heat loss.
              3.3.1.3. The connecting tube shall satisfy the following requirements:
                  (a) Be less than 3.6 metres long, or less than 6.1 metres long if heat-insulated. Its internal diameter shall not exceed 105 mm; the insulating materials shall have a thickness of at least 25 mm and thermal conductivity shall not exceed 0.1 W/m-1K-1 at 400 °C. Optionally, the tube may be heated to a temperature above the dew point. This may be assumed to be achieved if the tube is heated to 70 °C;
                  (b) Not cause the static pressure at the exhaust outlets on the vehicle being tested to differ by more than 0.75 kPa at 50 km/h, or more than 1.25 kPa for the duration of the test from the static pressures recorded when nothing is connected to the vehicle exhaust pipes. The pressure shall be measured in the exhaust outlet or in an extension having the same diameter and as near as possible to the end of the tailpipe. Sampling systems capable of maintaining the static pressure to within 0.25 kPa may be used if a written request from a manufacturer to the responsible authority substantiates the need for the tighter tolerance;
                  (c) No component of the connecting tube shall be of a material that might affect the gaseous or solid composition of the exhaust gas. To avoid generation of any particles from elastomer connectors, elastomers employed shall be as thermally stable as possible and have minimum exposure to the exhaust gas. It is recommended not to use elastomer connectors to bridge the connection between the vehicle exhaust and the connecting tube.
              3.3.2. Dilution air conditioning
              3.3.2.1. The dilution air used for the primary dilution of the exhaust in the CVS tunnel shall pass through a medium capable of reducing particles of the most