1.4. However, if the lamp manufacturer can prove that the product has already passed the tests prescribed in paragraphs 2.1 to 2.5 below, or the equivalent tests pursuant to another Regulation, those tests need not be repeated; only the tests prescribed in Appendix 1, table B, shall be mandatory.
1.5. If the headlamps are designed for right-hand installation only, or for left-hand installation only, tests pursuant to this Annex may be done on one sample only, at the choice of the applicant.
2. TESTS
2.1. Resistance to temperature changes
2.1.1. Tests
Three new samples (lenses) shall be subjected to five cycles of temperature and humidity (RH = relative humidity) change in accordance with the following programme:
3 hours at 40 ± 2 °C and 85-95 per cent RH;
1 hour at 23 ± 5 °C and 60-75 per cent RH;
15 hours at – 30 ± 2 °C;
1 hour at 23 ± 5 °C and 60-75 per cent RH;
3 hours at 80 ± 2 °C;
1 hour at 23 ± 5 °C and 60-75 per cent RH;
Before this test, the samples shall be kept at 23 ± 5 °C and 60-75 per cent RH for at least four hours.
Note: The periods of one hour at 23 ± 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 using a standard lamp, at the following points:
B 50 L and 50 R for the passing beam of a passing lamp or a passing/driving lamp (B 50 R and 50 L in the case of headlamps intended for left-hand traffic);
E
max
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 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 wave lengths smaller than 295 nm and greater than 2 500 nm. The samples shall be exposed to an energetic illumination of 1 200 W/m
2
± 200 W/m
2
for a period such that the luminous energy that they receive is equal to 4 500 MJ/m
2
± 200 MJ/m
2
. Within the enclosure, the temperature measured on the black panel placed on a level with the samples shall be 50 ± 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 min
–1
.
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