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TEST EQUIPMENT 3.1. Dynamometer brake No particular model is prescribed. However, its adjustment shall not be affected by the lapse of time. It shall not produce any perceptible vibrations in the vehicle likely to impair the latter's normal operation. It must be equipped with an inertia adapter enabling the operation of the vehicle on the road to be reproduced (equivalent inertias). 3.2. Gas-collection equipment 3.2.1. The connecting tubes shall be made of steel and shall, so far as possible, be provided with rigid connections. However, a completely gas-tight flexible ring element shall be used to isolate the device from the vehicle vibrations. Other materials may be used if they do not affect the composition of the gases. 3.2.2. If the vehicle being tested is equipped with an exhaust pipe comprising several branches, the branches shall be interlinked as near as possible to the vehicle. 3.2.3. The temperature of the gases in the collecting system shall be compatible with the correct operation of the engine, with maintenance of the sampling bags in good condition, with the hydrocarbon absorption level laid down in item 4.5.1 and with the reduction to a minimum of condensation on the sides of the sampling bag or bags. 3.2.4. The various valves used to direct the exhaust gases either to the atmosphere or to the sampling device shall be quickly adjustable and quick-acting. 3.2.5. The collecting device shall comprise one or more bags of adequate capacity. The bags shall be made of such materials as will not affect either the accuracy of the measurements or the conservation of the gases. 3.3. Analytical equipment 3.3.1. The sampling probe may consist of the sampling tube leading into the collecting device or of the bag-emptying tube. It may also be independent but in no case shall its opening be at the bottom of the bag. 3.3.2. Analysers shall be of the non-dispersive type with absorption in the infra-red. The hydrocarbons analyser shall be sensitised for n-hexane. 3.4. Volume-measuring equipment 3.4.1. A volumetric gauge shall be used. 3.4.2. Pressure and temperature measurements enabling the volume to be referred to standard conditions shall be carried out at points selected in the light of the type of gauge used. The laboratory shall specify their positions. 3.4.3. The gas-bleeding device may consist of a pump or of any other system which keeps the pressure measured at the gauge constant. 3.5. Accuracy of instruments 3.5.1. As the brake is calibrated in a separate test, the accuracy of the dynamometer is not indicated. The total inertia of the rotating masses, including that of the rollers and the rotating part of the brake (see item 4.2), shall be given to within ± 20 kg. 3.5.2. The speed of the vehicle shall be measured by the speed of rotation of the rollers connected to the brake flywheels. It shall be measurable to within ± 2 km/h in the speed range 0 to 10 km/h and to within ± 1 km/h for speeds above 10 km/h. 3.5.3. The temperatures considered in items 5.1.1 and 6.3.3 shall be measurable to within ± 2º C. 3.5.4. The atmospheric pressure shall be measurable to within ± 1 mm of mercury. 3.5.5. The vacuum in the vehicle's intake system shall be measurable to within ± 5 mm of mercury. The other pressures (backpressure in the sampling device, pressure for correction of volume etc.) must be measurable to within ± 5 mm water gauge. 3.5.6. The size and accuracy of the gauge shall be appropriate to the volume of gas to be measured, so that the measurement of volume is accurate to within ± 2 %. 3.5.7. The analysers shall have a measuring range compatible with the accuracy required to measure the content of the various constituents to within ± 3 %, disregarding the accuracy of the standard (calibration) gases. The overall response time of the analysing circuit shall be less than one minute. 3.5.8. The content of the standard gases shall not differ by more than ± 2 % from the reference value of each gas. The diluent shall be nitrogen.

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Source: EUR-Lex (Cellar) · retrieved 2026-11-01 · Text as adopted (Official Journal); later amendments are not incorporated in this text.