Document ID: chunk:federal_register_of_legislation:F2021C00509:front:0:p26
Version: federal_register_of_legislation:F2021C00509
Segment Type: other
Provision Reference: 
Character Range: 77389–80245

1.2.1. Using standard parts and observing the vehicle manufacturer's instructions, the exhaust system or components thereof must be fitted to the vehicle referred to in paragraph 3.3. of this Regulation or the engine referred to in paragraph 3.4. of this Regulation. In the former case the vehicle must be mounted on a roller dynamometer. In the second case, the engine must be coupled to a dynamometer.

           1.2.2. The test must be conducted in six six-hour periods with a break of at least 12 hours between each period in order to reproduce the effects of cooling any condensation which may occur.

           1.2.3. During each six-hour period, the engine shall be run, under the following conditions in turn:
            (1) Five minutes at idling speed;
            (2) One-hour sequence under 1/4 load at 3/4 of rated maximum speed (S);
            (3) One-hour sequence under 1/2 load at 3/4 of rated maximum speed (S);
            (4) 10-minute sequence under full load at 3/4 of rated maximum speed (S);
            (5) 15-minute sequence under 1/2 load at rated maximum speed (S);
            (6) 30-minute sequence under 1/4 load at rated maximum speed (S);
            Total duration of the six sequences: three hours.
            Each period must comprise two sets of the six above-mentioned sequences.

           1.2.4. During the test, the silencer must not be cooled by a forced draught simulating normal airflow around the vehicle. Nevertheless, at the request of the manufacturer, the silencer may be cooled in order not to exceed the temperature recorded at its inlet when the vehicle is running at maximum speed.

           1.3. Conditioning by pulsation

           1.3.1. The exhaust system or components thereof must be fitted to the vehicle referred to in paragraph 3.3 of this Regulation or the engine referred to in paragraph 3.4 of this Regulation. In the former case the vehicle must be mounted on a roller dynamometer. In the second case, the engine must be mounted on a dynamometer. The test apparatus, a detailed diagram of which is shown in Figure 3 of the appendix to this annex must be fitted at the outlet of the exhaust system. Any other apparatus providing equivalent results is acceptable.

           1.3.2. The test apparatus must be adjusted in a such a way that the exhaust-gas flow is alternatively interrupted and re-established by the quick-action valve for 2,500 cycles.

           1.3.3. The valve must open when the exhaust-gas back pressure, measured at least 100 mm downstream of the intake flange, reaches a value of between 0.35 and 0.40 bar. It must close when this pressure does not differ by more than 10 %from its stabilized value with the valve open.

           1.3.4. The time-delay switch shall be set for the duration of gas exhaust resulting from the provisions laid down in paragraph