Division 3.3.6 Recommended system description

Figure A5/3 is a schematic drawing of exhaust dilution systems that meet the requirements of this Sub-Annex.

The following components are recommended:

1. (a)

   A dilution air filter, which may be pre-heated if necessary. This filter shall consist of the following filters in sequence: an optional activated charcoal filter (inlet side), and a HEPA filter (outlet side). It is recommended that an additional coarse particle filter be situated before the HEPA filter and after the charcoal filter, if used. The purpose of the charcoal filter is to reduce and stabilize the hydrocarbon concentrations of ambient emissions in the dilution air;

2. (b)

   A connecting tube by which vehicle exhaust is admitted into a dilution tunnel;

3. (c)

   An optional heat exchanger as described in paragraph 3.3.5.1. of this Sub-Annex;

4. (d)

   A mixing device in which exhaust gas and dilution air are mixed homogeneously, and which may be located close to the vehicle so that the length of the connecting tube is minimized;

5. (e)

   A dilution tunnel from which particulate and particles are sampled;

6. (f)

   Some form of protection for the measurement system may be used e.g. a cyclone separator, bulk stream filter, etc.;

7. (g)

   A suction device of sufficient capacity to handle the total volume of diluted exhaust gas.

Exact conformity with these figures 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.