Document ID: chunk:federal_register_of_legislation:F2015C00542:reg:254:p3
Version: federal_register_of_legislation:F2015C00542
Segment Type: reg
Provision Reference: reg 254 (pt 3/18)
Character Range: 106059–108889

and corrected for chromatic aberrations. The full aperture of the lens shall not exceed f/20. The distance between the lens and the light source shall be adjusted in order to obtain a light beam which is substantially parallel. A diaphragm shall be inserted to limit the diameter of the light beam
              to 7 mm ± 1 mm. This diaphragm shall be situated at a distance of
              100 mm ± 50 mm from the lens on the side remote from the light source.

              4.1.5. Equipment for measuring scattered light (see Figure 5), consisting of a photoelectric cell with an integrating sphere 200 to 250 mm in diameter. The sphere shall be equipped with entrance and exit ports for the light. The entrance port shall be circular and have a diameter at least twice that of the light beam. The exit port of the sphere shall be provided with either a light trap or a reflectance standard, according to the procedure described in paragraph 4.4.3. below. The light trap shall absorb all the light when no test piece is inserted in the light beam.

               The axis of the light beam shall pass through the centre of the entrance and exit ports. The diameter b of the light-exit port shall be equal to 2 a.tan 4°, where a. is the diameter of the sphere. The photoelectric cell shall be mounted in such a way that it cannot be reached by light coming directly from the entrance port or from the reflectance standard.

               The surfaces of the interior of the integrating sphere and the reflectance standard shall be of substantially equal reflectance and shall be matt and non-selective.

               The output of the photoelectric cell shall be linear within ±2 per cent over the range of luminous intensities used. The design of the instrument shall be such that there is no galvanometer deflection when the sphere is dark.

               The whole apparatus shall be checked at regular intervals by means of calibration standards of defined haze.

               If haze measurements are made using equipment or methods differing from those defined above, the results shall be corrected, if necessary, to bring them into agreement with those obtained by the apparatus described above.

Figure 5

Hazemeter

       4.2. Test conditions

               Temperature:  20 °C ± 5 °C

               Pressure:  860 to 1,060 mbar

               Relative humidity: 60 ± 20 per cent.

              4.3. Test pieces

               The test pieces shall be flat squares of side 100 mm having both surfaces substantially plane and parallel and having a fixing hole 6.4           mm in diameter drilled in the center, if necessary.

              4.4. Procedure

               The abrasion test shall be carried out on that surface of the test piece which represents the outside face of the glazing when the