Document ID: chunk:federal_register_of_legislation:F2024L00447:reg:0:p23
Version: federal_register_of_legislation:F2024L00447
Segment Type: reg
Provision Reference: reg 0 (pt 23/57)
Character Range: 155563–158714

Exhaust gases may be measured wet or dry. A gas-drying device, if used, shall have a minimal effect on the composition of the measured gases. Chemical dryers are not permitted.

              4.3. Additional requirements

              4.3.1. General

              The provisions in paragraphs 4.3.2. to 4.3.5. define additional performance requirements for specific analyser types and apply only to cases in which the analyser under consideration is used for RDE emission measurements.

              4.3.2. Efficiency test for NOX converters

              If a NOX converter is applied, for example to convert NO2 into NO for analysis with a chemiluminescence analyser, its efficiency shall be tested by following the requirements in paragraph 5.5. of Annex B5 to UN Regulation No. 154 on WLTP. The efficiency of the NOX converter shall be verified no longer than one month before the emissions test.

              4.3.3. Adjustment of the Flame Ionisation Detector (FID)

              (a) Optimization of the detector response

                  If hydrocarbons are measured, the FID shall be adjusted as specified by the instrument manufacturer by following paragraph 5.4.1. of Annex B5 to UN Regulation No. 154 on WLTP. A propane-in-air or propane-in-nitrogen span gas shall be used to optimize the response in the most common operating range.

              (b) Hydrocarbon response factors

                  If hydrocarbons are measured, the hydrocarbon response factor of the FID shall be verified by following the provisions of paragraph 5.4.3. of Annex B5 to UN Regulation No. 154 on WLTP, using propane-in-air or propane-in-nitrogen as span gases and purified synthetic air or nitrogen as zero gases, respectively.

              (c) Oxygen interference check

                  The oxygen interference check shall be performed when introducing a FID into service and after major maintenance intervals. A measuring range shall be chosen in which the oxygen interference check gases fall in the upper 50 per cent. The test shall be conducted with the oven temperature set as required. The specifications of the oxygen interference check gases are described in paragraph 5.3.

                  The following procedure applies:

                     (i) The analyser shall be set at zero;

                     (ii) The analyser shall be spanned with a 0 per cent oxygen blend for positive ignition engines and a 21 per cent oxygen blend for compression ignition engines;

                     (iii) The zero response shall be rechecked. If it has changed by more than 0.5 per cent of full scale, steps (i) and (ii) shall be repeated;

                     (iv) The 5 per cent and 10 per cent oxygen interference check gases shall be introduced;

                     (v) The zero response shall be rechecked. If it has changed by more than ±1 per cent of full scale, the test shall be repeated;

                     (vi) The oxygen interference EO2 [%] shall be calculated for each oxygen interference check gas in step (iv) as follows:

                   where the analyser response is:

                   where:

cref,b  is the