Document ID: chunk:federal_register_of_legislation:F2023C00229:reg:9:p52
Version: federal_register_of_legislation:F2023C00229
Segment Type: reg
Provision Reference: reg 9 (pt 52/71)
Character Range: 356640–359429

of the raw exhaust gas. A control system consisting of two pressure control valves PCV1 and PCV2 is necessary for proportional splitting by controlling the pressures in EP and DT.

              FD3 Flow divider (Figure 17)

              A set of tubes (multiple tube unit) is installed in the exhaust pipe EP to provide a proportional sample of the raw exhaust gas. One of the tubes feeds exhaust gas to the dilution tunnel DT, whereas the other tubes exit exhaust gas to a damping chamber DC. The tubes must have the same dimensions (same diameter, length, bend radius), so that the exhaust split depends on the total number of tubes. A control system is necessary for proportional splitting by maintaining a differential pressure of zero between the exit of the multiple tube unit into DC and the exit of TT. Under these conditions, exhaust gas velocities in EP and FD3 are proportional, and the flow TT is a constant fraction of the exhaust gas flow. The two points have to be connected to a differential pressure transducer DPT. The control to provide a differential pressure of zero is done with the flow controller FC1.

              EGA Exhaust gas analyser (Figures 13, 14, 15, 16, 17)

              CO2 or NOx analysers may be used (with carbon balance method CO2 only). The analysers shall be calibrated like the analysers for the measurement of the gaseous emissions. One or several analysers may be used to determine the concentration differences. The accuracy of the measuring systems has to be such that the accuracy of GEDFW,i is within ± 4 %.

              TT Transfer tube (Figures 11 to 19)

              The transfer tube shall be:
                —    as short as possible, but not more than 5 m in length,

                —    equal to or greater than the probe diameter, but not more than 25 mm in diameter,

                —    exiting on the centreline of the dilution tunnel and pointing downstream.

              If the tube is 1 meter or less in length, it shall be insulated with material with a maximum thermal conductivity of 0,05 W/m*K with a radial insulation thickness corresponding to the diameter of the probe. If the tube is longer than 1 meter, it must be insulated and heated to a minimum wall temperature of 523 K (250 °C).

              DPT Differential pressure transducer (Figures 11, 12, 17)

              The differential pressure transducer shall have a range of ± 500 Pa or less.

              FC1 Flow controller (Figures 11, 12, 17)

              For isokinetic systems (Figures 11,12), a flow controller is necessary to maintain a differential pressure of zero between EP and ISP. The adjustment can be done by:

                (a)    controlling the speed or flow of the suction blower SB and keeping the speed or flow of the