Document ID: chunk:federal_register_of_legislation:F2023L00129:reg:1800:p6
Version: federal_register_of_legislation:F2023L00129
Segment Type: reg
Provision Reference: reg 1800 (pt 6/12)
Character Range: 518878–521571

the end of the probe and the dilution stage;
 or
(b) Not more than 1 m in length, if heated above 150 °C for 90 per cent of the total length, as measured between the end of the probe and the dilution stage.
 It shall be equal to or greater than the probe diameter, but not more than 25 mm in diameter, and exiting on the centreline of the dilution tunnel and pointing downstream.
 With respect to point (a) above, insulation shall be done with material with a maximum thermal conductivity of 0.05 W/mK with a radial insulation thickness corresponding to the diameter of the probe.
 FC1 Flow controller
 A flow controller shall be used to control the diluent flow through the pressure blower PB and/or the suction blower SB. It may be connected to the exhaust flow sensor signals specified in paragraph 8.4.1. of this annex. The flow controller may be installed upstream or downstream of the respective blower. When using a pressurized air supply, FC1 directly controls the airflow.
 FM1 Flow measurement device
 Gas meter or other flow instrumentation to measure the diluent flow. FM1 is optional if the pressure blower PB is calibrated to measure the flow.
DAF Diluent filter
 The diluent (ambient air, synthetic air, or nitrogen) shall be filtered with a high-efficiency (HEPA) filter that has an initial minimum collection efficiency of 99.97 per cent according to EN 1822-1 (filter class H14 or better), ASTM F 1471‑93 or equivalent standard.
 FM2 Flow measurement device (fractional sampling type, Figure 13 only)
 Gas meter or other flow instrumentation to measure the diluted exhaust gas flow. FM2 is optional if the suction blower SB is calibrated to measure the flow.
 PB Pressure blower (fractional sampling type, Figure 13 only)
 To control the diluent flow rate, PB may be connected to the flow controllers FC1 or FC2. PB is not required when using a butterfly valve. PB may be used to measure the diluent flow, if calibrated.
 SB Suction blower (fractional sampling type, Figure 13 only)
 SB may be used to measure the diluted exhaust gas flow, if calibrated.
 DT Dilution tunnel (partial flow)
 The dilution tunnel:
(a) Shall be of a sufficient length to cause complete mixing of the exhaust and diluent under turbulent flow conditions (Reynolds number, Re, greater than 4,000, where Re is based on the inside diameter of the dilution tunnel) for a fractional sampling system, i.e. complete mixing is not required for a total sampling system;
(b) Shall be constructed of stainless steel;
(c) May be heated to no greater than 325 K (52 °C) wall temperature;
(d) May be insulated.
 PSP Particulate sampling probe (fractional sampling type, Figure 13 only)
 The particulate sampling