Council Directive of 2 August 1972 on the approximation of the laws of the Member States relating to the measures to be taken against the emission of pollutants from diesel engines for use in vehicles (72/306/EEC) (repealed)

ANNEX [F1 VII] U.K. INSTALLATION AND USE OF THE OPACIMETER

Textual Amendments

F1 Substituted by Commission Directive 2005/21/EC of 7 March 2005 adapting to technical progress Council Directive 72/306/EEC on the approximation of the laws of the Member States relating to the measures to be taken against the emission of pollutants from diesel engines for use in vehicles (Text with EEA relevance).

1. SCOPE U.K.

This annex specifies the installation and use of opacimeters for the tests described in Annexes III and IV.

2. SAMPLING OPACIMETER U.K.

2.1. Installation for steady-speed tests U.K.

2.1.1. The ratio of the cross-sectional area of the probe to that of the exhaust pipe shall not be less than 0·05. The back pressure measured in the exhaust pipe at the intake of the probe shall not exceed 75 mm (water gauge). U.K.

2.1.2. The probe shall be a tube with an open end facing forwards in the axis of the exhaust pipe, or of the extension pipe if one is required. It shall he situated in a section where the distribution of smoke is approximately uniform. To achieve this, the probe shall be placed as far downstream in the exhaust pipe as possible, or, if necessary, in an extension pipe so that, if D is the diameter of the exhaust pipe at the outlet, the end of the probe is situated in a straight portion at least 6 D in length upstream of the sampling point and 3 D in length downstream. If an extension pipe is used, no air shall be allowed to enter the joint. U.K.

2.1.3. The pressure in the exhaust pipe and the characteristics of the pressure drop in the sampling line shall be such that the probe collects a sample substantially equivalent to that which would be obtained by isokinetic sampling. U.K.

2.1.4. If necessary, an expansion tank of compact design and of sufficient capacity to damp the pulsations may be incorporated in the sampling line as near to the probe as possible. A cooler may also be fitted. U.K.

The design of the expansion tank and cooler shall not unduly disturb the composition of the exhaust gas.

2.1.5. A butterfly valve or other means of increasing the sampling pressure may be placed in the exhaust pipe at least three 3 D downstream from the sampling probe. U.K.

2.1.6. The connecting pipes between the probe, the cooling device, the expansion tank (if required) and the opacimeter shall be as short as possible while satisfying the pressure and temperature requirements described in [F1 Annex VI], items 3.8 and 3.9. The pipe shall be inclined upwards from the sampling point to the opacimeter, and sharp bends where soot might accumulate shall be avoided. If not embodied in the opacimeter, a bypass valve shall be provided upstream. U.K.

2.1.7. A check shall be carried out during the test to ensure that the requirements of [F1 Annex VI, item 3.8, concerning pressure and those of Annex VI], item 3.9, concerning the temperature in the measuring chamber are observed. U.K.

2.2. Installation for tests under free acceleration U.K.

2.2.1. The ratio of the cross-sectional area of the probe to that of the exhaust pipe shall not be less thas 0·05. The back pressure measured in the exhaust pipe at the intake of the probe shall not exceed 75 mm (water gauge). U.K.

2.2.2. The probe shall be a tube with an open end facing forwards in the axis of the exhaust pipe, or of the extension pipe if one is required. It shall be situated in a section where the distribution of smoke is approximately uniform. To achieve this, the probe shall be placed as far downstream in the exhaust pipe as possible or, if necessary, in an extension pipe so that, if D is the diameter of the exhaust pipe at the outlet, the end of the probe is situated in a straight portion at least 6 D in length upstream of the sampling point and 3 D in length downstream. If an extension pipe is used, no air shall be allowed to enter the joint. U.K.

2.2.3. The sampling system shall be such that at all engine speeds the pressure of the sample at the opacimeter is within the limits specified in [F1 Annex VI], item 3.8.2. This may be checked by noting the sample pressure at engine idling and maximum no-load speeds. Depending on the characteristics of the opacimeter, control of sample pressure can be achieved by a fixed restriction or a butterfly valve in the exhaust pipe or extension pipe. Whichever method is used, the back pressure measured in the exhaust pipe at the intake of the probe shall not exceed 75 mm (water gauge). U.K.

2.2.4. The pipes connecting with the opacimeter shall be as short as possible. The pipe shall be inclined upwards from the sampling point to the opacimeter, and sharp bends where soot might accumulate shall be avoided. A bypass valve may be provided upstream of the opacimeter to isolate it from the exhaust-gas flow when no measurement is being made. U.K.

3. FULL-FLOW OPACIMETER U.K.

The only general precautions to be observed in steady-speed and free-acceleration tests are the following:

3.1. Joints in the connecting pipes between the exhaust pipe and the opacimeter shall not allow air to enter from outside. U.K.

3.2. The pipes connecting with the opacimeter shall be as short as possible, as in the case of sampling opacimeters. The pipe system shall be inclined upwards from the exhaust pipe to the opacimeter, and sharp bends where soot might accumulate shall be avoided. A bypass valve may be provided upstream of the opacimeter to isolate it from the exhaust-gas flow when no measurement is being made. U.K.

3.3. A cooling system may also he required upstream of the opacimeter. U.K.