Document ID: chunk:federal_register_of_legislation:F2023C00228:reg:1:p33
Version: federal_register_of_legislation:F2023C00228
Segment Type: reg
Provision Reference: reg 1 (pt 33/35)
Character Range: 531395–534173

the test, the samples shall be dried at 50°C + 5°C.

       The surface of the samples shall be cleaned with a moist cloth.

       2.3.2.  Resistance to hydrocarbons

       The outer face of these three samples shall then be lightly rubbed for one minute with a cotton cloth soaked in a mixture composed of 70 per cent n-heptane and 30 per cent toluene (volume per cent), and shall then be dried in the open air.

       2.3.3.  Results

       After the above two tests have been performed successively, the mean value of the variation in transmission  , measured on the three samples according to the procedure described in Appendix 2 to this annex shall not exceed 0.010 (Δtm < 0.010).

       2.4.  Resistance to mechanical deterioration

       2.4.1.  Mechanical deterioration method

       The outer face of the three new samples (lenses) shall be subjected to the uniform mechanical deterioration test by the method described in Appendix 3 to this annex.

       2.4.2.  Results

       After this test, the variations:

                       in transmission: ,

                       and in diffusion: ,

       shall be measured according to the procedure described in Appendix 2 in the area specified in paragraph 2.2.4.1.1. of this Regulation. The mean value of the three samples shall be such that:

 Δtm < 0.100;

 Δdm < 0.050.

       2.5.  Test of adherence of coatings, if any

       2.5.1.  Preparation of the sample

       A surface of 20 mm x 20 mm in area of the coating of a lens shall be cut with a razor blade or a needle into a grid of squares approximately 2 mm x 2 mm. The pressure on the blade or needle shall be sufficient to cut at least the coating.

       2.5.2.  Description of the test

       Use an adhesive tape with a force adhesion of 2 N/(cm of width)  20 per cent measured under the standardized conditions specified in Appendix 4 to this annex. This adhesive tape, which shall be at least 25 mm wide, shall be pressed for at least five minutes to the surface prepared as prescribed in paragraph 2.5.1.

       Then the end of the adhesive tape shall be loaded in such a way that the force of adhesion to the surface considered is balanced by a force perpendicular to that surface. At this stage, the tape shall be torn off at a constant speed of 1.5 m/s + 0.2 m/s.

       2.5.3.  Results

       There shall be no appreciable impairment of the gridded area.  Impairments at the intersections between squares or at the edges of the cuts shall be permitted, provided that the impaired area does not exceed 15 per cent of the gridded surface.

       2.6.  Tests of the complete headlamp incorporating a lens of plastic material

       2.6.1.  Resistance to mechanical deterioration of the lens surface

       2.6.1.1.  Tests