Document ID: chunk:federal_register_of_legislation:F2015C00542:reg:254:p8
Version: federal_register_of_legislation:F2015C00542
Segment Type: reg
Provision Reference: reg 254 (pt 8/18)
Character Range: 119806–122843

dimensions of the test pieces shall norma11y be those specified in the appropriate test method for the property or properties to be measured after exposure.

               The number of control and test pieces for each test condition or exposure stage shall be determined, in addition to those required for visual evaluations by the number required by the test methods.

               It is recommended that visual evaluations be conducted on the largest test pieces tested.

              6.4.1.3. Procedure

               Measure, according to paragraph 9.1. of this annex the luminous transmission of the test specimen(s) to be exposed. Measure, according to paragraph 4. of this annex, the resistance to abrasion of the surface(s) of the control piece(s). That face of each test pieces, which would represent the surface glazed to the exterior of the road vehicle, shall face the lamp. Other exposure conditions shall be as follows:

              6.4.1.3.1. The irradiance shall not vary more than ±10 per cent over the whole test specimen area.

              6.4.1.3.2. At appropriate intervals, clean lamp filters by washing with detergent and water. Xenon arc filters shall be replaced according to the recommendations of the equipment manufacturer.

              6.4.1.3.3. The temperature within the exposure apparatus during the dry portion of the cycle shall be controlled by circulation of sufficient air to maintain a constant black standard temperature.

               In the xenon arc exposure apparatus, this temperature shall be 70 °C ± 3 °C as indicated by a Black standard thermometer or equivalent.

               The black panel thermometer shall be mounted in the test specimen rack and readings shall be taken at the point where maximum heat is developed due to light exposure.

              6.4.1.3.4. The relative humidity within the exposure apparatus shall be controlled at
              50 ± 5 per cent during the dry portions of the cycle.

              6.4.1.3.5. The deionized water used in the spray cycle shall contain less than 1 ppm silicon dioxide solids and shall leave no permanent deposit or residue on the test specimens which would interfere with subsequent measurements.

              6.4.1.3.6. The pH of the water shall be between 6.0 and 8.0, and the conductivity shall be less than 5 microsiemens.

              6.4.1.3.7. The temperature of the water in the line where it enters the exposure apparatus shall be the ambient water temperature.

              6.4.1.3.8. The water shall strike the test specimens in the form of a fine spray in sufficient volume to wet the test specimens uniformly, immediately upon impact.

               Water spray will be directed only against the test specimen surface facing the light source. No recirculation of the spray water or immersion of the test specimens in the water shall be permitted.

              6.4.1.3.9. The test specimens shall be rotated about the arc in order to provide uniform distribution of the light. All positions