Document ID: chunk:federal_register_of_legislation:F2023C00154:front:0:p34
Version: federal_register_of_legislation:F2023C00154
Segment Type: other
Provision Reference: 
Character Range: 88014–90609

periods of one hour at 23 °C ± 5 °C shall include the periods of transition from one temperature to another which are needed in order to avoid thermal shock effects.
2.1.2. Photometric measurements
2.1.2.1. Method
Photometric measurements shall be carried out on the samples before and after the test. These measurements shall be made under the conditions as specified in paragraph 6.3. or 6.4. of this Regulation, at the following points:
In the case of Class "B" front fog lamps:
(a) At point HV and
(b) Point h = 0, v = 2° D in zone D.
In the case of Class "F3" front fog lamps:
(a) Intersection VV line with line 6 and
(b) Intersection VV line with line 4.
2.1.2.2. Results
The variation between the photometric values measured on each sample before and after the test shall not exceed 10 per cent 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 5,500 K and 6,000 K. Appropriate filters shall be placed between the source and the samples so as to reduce as far as possible radiations with wavelengths smaller than 295 nm and greater than 2,500 nm. 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 °C ± 5 °C. In order to ensure a regular exposure, the samples shall revolve around the source of radiation at a speed between 1 and 5 1/min.
The samples shall be sprayed with distilled water of conductivity lower than 1 µS/m at a temperature of 23 °C ± 5 °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 per cent n-heptane, 12.5 per cent toluene, 7.5 per cent ethyl tetrachloride, 12.5 per cent trichlorethylene and 6 per cent xylene (volume per cent).
2.2.2.2. Application of the test mixture
Soak a piece of cotton cloth (as per ISO 105) until