Document ID: chunk:federal_register_of_legislation:F2008C00323:reg:20:p15
Version: federal_register_of_legislation:F2008C00323
Segment Type: reg
Provision Reference: reg 20 (pt 15/23)
Character Range: 187144–190394

materials shall be such that the system does not influence the pollutant concentration in the diluted exhaust gas. Should any component (heat exchanger, blower, etc.) change the concentration of any pollutant gas in the diluted gas, the sampling for that pollutant shall be carried out before that component if the problem cannot be corrected.

           4.2.7.   If the vehicle being tested is equipped with an exhaust pipe comprising several branches, the connecting tubes shall be connected as near as possible to the vehicle without adversely affecting his operation.

           4.2.8.   Static pressure variations at the exhaust(s) of the vehicle shall remain within  1.25 kPa of the static pressure variations measured during the dynamometer driving cycle and with no connection to the exhaust(s). Sampling systems capable of maintaining the static pressure to within  0.25 kPa are used if a written request from a manufacturer to the administration granting the approval substantiates the need for the closer tolerance. The back-pressure shall be measured in the exhaust pipe as near as possible to its end or in an extension having the same diameter.

           4.2.9.   The various valves used to direct the exhaust gases shall be of a quick-adjustment, quick-acting type.

           4.2.10.  The gas samples are collected in sample bags of adequate capacity. These bags shall be made of such materials as will not change the pollutant gas by more than  2 per cent after 20 minutes of storage.

           4.3.   Analytical equipment

           4.3.1.   Provisions

           4.3.1.1.  Pollutant gases shall be analysed with the following instruments:

           Carbon monoxide (CO) and carbon dioxide (CO2)analysis:
           Analysers shall be of the non-dispersive infra-red (NDIR) absorption type.

           Hydrocarbons (HC) analysis - spark-ignition engines:
           The analyser shall be of the flame ionisation (FID) type calibrated with propane gas expressed equivalent to carbon atoms (C1).

           Hydrocarbons (HC) analysis - compression-ignition engines:
           The analyser shall be of the flame ionisation type with detector, valves, pipework, etc., heated to 463 K (190 C)  10 K (HFID). It shall be calibrated with propane gas expressed equivalent to carbon atoms (C1).

           Nitrogen oxide (NOx) analysis:
           The analyser shall be either of the chemi-luminescent (CLA) or of the non-dispersive ultra-violet resonance absorption (NDUVR) type, both with an NOx-NO converter.

           Particulates - Gravimetric determination of the particulates collected:

           These particulates shall in each case be collected by two series-mounted filters in the sample gas flow. The quantity of particulates collected by each pair of filters shall be as follows:
           where:

                   Vep : flow through filters;

                   Vmix  : flow through tunnel;

                   M : particulate mass (g/km);

                   Mlimit  : limit mass of particulates (limit mass in force, g/km);

                   m : mass of particulates collected by filters (g);

                   d : distance corresponding to the operating cycle (km).

           The particulates