ANNEX [F1 VI] U.K. CHARACTERISTICS OF OPACIMETERS

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).

4. EFFECTIVE LENGTH ‘L’ OF THE OPACIMETER U.K.

4.1. General U.K.

4.1.1. In some types of opacimeter the gas between the light source and the photoelectric cell, or between transparent parts protecting the source and the photoelectric cell, is not of constant opacity. In such cases the effective length L shall be that of a column of gas of uniform opacity which gives the same absorption of light as that obtained when the gas is admitted in a normal way into the opacimeter. U.K.

4.1.2. The effective length of the light path is obtained by comparing the reading N of the opacimeter operating normally with the reading N_o obtained with the opacimeter modified so that the test gas fills a well defined length L_o. U.K.

4.1.3. It will be necessary to take comparative readings in quick succession to determine the correction to be made for shifts of zero. U.K.