Document ID: chunk:federal_register_of_legislation:F2008C00323:reg:120:p7
Version: federal_register_of_legislation:F2008C00323
Segment Type: reg
Provision Reference: reg 120 (pt 7/23)
Character Range: 254988–257947

mm in diameter and the system shall be earthed.

         2.4.4. The particulate sampling system shall consist of a sampling probe in the dilution tunnel and two series-mounted filters. Quick-acting valves shall be located both up and downstream of the two filters in the direction of flow.

         The configuration of the sample probe shall be as indicated in Figure 5/2.

         2.4.5. The particulate sampling probe shall meet the following conditions:

         It shall be installed near the tunnel centreline, roughly ten tunnel diameters downstream of the gas inlet, and have an internal diameter of at least 12 mm.

         The distance from the sampling tip to the filter mount shall be at least five probe diameters, but shall not exceed 1,020 mm.

         2.4.6. The sample gas flow measuring unit shall consist of pumps, gas flow regulators and flow measuring units.

         2.4.7. The hydrocarbon sampling system shall consist of a heated sampling probe, line, filter and pump. The sampling probe shall be installed at the same distance from the exhaust gas inlet as the particulate sampling probe, in such a way that neither interferes with samples taken by the other. It shall have a minimum internal diameter of 4 mm.

         2.4.8. All heated parts shall be maintained at a temperature of 463 K (190 C)  10 K by the heating system.

         2.4.9. If it is not possible to compensate for variations in the flow rate provision shall be made for a heat exchanger and a temperature control device as specified in paragraph 2.3.3.1. so as to ensure that the flow rate in the system is constant and the sampling rate accordingly proportional.

Figure 5/2

Particulate sampling probe configuration

         3.  DESCRIPTION OF THE DEVICES

         3.1.  Variable dilution device with positive displacement pump
         (PDP-CVS) (Figure 5/3)

         3.1.1.  The positive displacement pump - constant volume sampler (PDP-CVS) satisfies the requirements of this annex by metering the flow of gas through the pump at constant temperature and pressure. The total volume is measured by counting the revolutions made by the calibrated positive displacement pump. The proportional sample is achieved by sampling with pump, flow-meter and flow control valve at a constant flow rate.

         3.1.2. Figure 5/3 is a schematic drawing of such a sampling system. Since various configurations can produce accurate results, exact conformity with the drawing is not essential. Additional components such as instruments, valves, solenoids and switches may be used to provide additional information and co-ordinate the functions of the component system.

         3.1.3. The sampling equipment consists of:

         3.1.3.1. a filter (D) for the dilution air, which can be preheated if necessary. This filter shall consist of activated charcoal sandwiched between two layers of paper, and shall be used to reduce and stabilise the hydrocarbon