Document ID: chunk:federal_register_of_legislation:F2023L00129:reg:1800:p9
Version: federal_register_of_legislation:F2023L00129
Segment Type: reg
Provision Reference: reg 1800 (pt 9/12)
Character Range: 526321–529093

EFC Electronic flow compensation (optional)
 If the temperature at the inlet to the PDP, CFV or SSV is not kept within the limits stated above, a flow compensation system is required for continuous measurement of the flow rate and control of the proportional sampling into the double dilution system. For that purpose, the continuously measured flow rate signals are used to maintain the proportionality of the sample flow rate through the particulate filters of the double dilution system (see Figure 17) within 2.5 per cent.
 DT Dilution tunnel (full flow)
 The dilution tunnel:
(a) Shall be small enough in diameter to cause turbulent flow (Reynolds number, Re, greater than 4,000, where Re is based on the inside diameter of the dilution tunnel) and of sufficient length to cause complete mixing of the exhaust and diluent;
(b) May be insulated;
(c) May be heated up to a wall temperature sufficient to eliminate aqueous condensation.
 The engine exhaust shall be directed downstream at the point where it is introduced into the dilution tunnel, and thoroughly mixed. A mixing orifice may be used.
 For the double dilution system, a sample from the dilution tunnel is transferred to the secondary dilution tunnel where it is further diluted, and then passed through the sampling filters (Figure 17). The secondary dilution system shall provide sufficient secondary diluent to maintain the doubly diluted exhaust stream at a temperature between 315 K (42 °C) and 325 K (52 °C) immediately before the particulate filter.
 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.
 PSP Particulate sampling probe
 The probe is the leading section of PTT and:
(a) Shall be installed facing upstream at a point where the diluent and exhaust gases are well mixed, i.e. on the dilution tunnel DT centreline of the dilution systems, approximately 10 tunnel diameters downstream of the point where the exhaust enters the dilution tunnel;
(b) Shall be of 8 mm minimum inside diameter;
(c) May be heated to no greater than 325 K (52 °C) wall temperature by direct heating or by diluent pre-heating, provided the air temperature does not exceed 325 K (52 °C) prior to the introduction of the exhaust in the dilution tunnel;
(d) May be insulated.
A.2.2.5. Description of particulate sampling system
 The particulate sampling system is required for collecting the particulates on the particulate filter and is shown in Figures 16 and 17. In the case of total sampling partial flow dilution, which consists of passing the entire diluted exhaust sample