Document ID: chunk:federal_register_of_legislation:F2023C00142:reg:21:p12
Version: federal_register_of_legislation:F2023C00142
Segment Type: reg
Provision Reference: reg 21 (pt 12/15)
Character Range: 63896–66704

left-hand traffic);
         Emax for the driving beam of a driving lamp or a passing/driving lamp.
         2.1.2.2. Results
         The variation between the photometric values measured on each sample before and after the test shall not exceed 10 % including the tolerances of the photometric procedure.
         2.2. Resistance to atmospheric and chemical agents
         2.2.1. Resistance to atmospheric agents
         Three new, samples (lenses or samples of material) shall be exposed to radiation from a source having a spectral energy distribution similar to that of a black body at a temperature between 5,500K and 6,000K.  Appropriate filters shall be placed between the source and the samples so as to reduce as far as .... possible radiations with wave lengths smaller, than 295 mm and greater than 2,500 mm.  The samples shall be exposed to an energetic illumination of 1,200 W/m2 +/- 200 W/m2 for a period such that the luminous energy that they receive is equal to 4,500 MJ/m2 +/- 200 MJ/m2.  Within the enclosure, the temperature measured on the black panel placed on a level with the samples shall be 50 degrees C+5 degrees C.  In order to ensure a regular exposure, the samples shall revolve around the source of radiation at a speed between 1 and 5 min-1.   The samples shall be sprayed with distilled water of conductivity lower than 1 mS/m at a temperature of 23 degrees C +/- 5 degrees C, in accordance with the following cycle: spraying: 5 minutes; drying:25 minutes.
         2.2.2. Resistance to chemical agents
         After the test described in paragraph 2.2.1. above and the measurement described in paragraph 2.2.3.1. below have been carried out, the outer face of the said three samples shall be treated as described in paragraph 2.2.2.2. with the mixture defined in paragraph 2.2.2.1. below.
         2.2.2.1. Test mixture
         The test mixture shall be composed of 61.5 % n-heptane, 12.5 % toluene, 7.5 % ethyl tetrachloride, 12.5 % trichloroethylene and 6 % xylene (volume %).

         2.2.2.2. Application of the test mixture
         Soak a piece of cotton cloth (as per ISO 105) until saturation with the mixture defined   in paragraph 2.2.2.1. above and, within 10 seconds, apply it for 10 minutes to the outer face of the sample at a pressure of 50 N/cm2, corresponding to an effort of 100 N applied on a test surface of 14 x 14 mm.
         During this 10-minute period, the cloth pad shall be soaked again with the mixture so that the composition of the liquid applied is continuously identical with that of the test mixture prescribed.
         During the period of application, it is permissible to compensate the pressure applied to the sample in order to prevent it from causing cracks.
         2.2.2.3. Cleaning
         At the end of the application of