GB/T 31973-2015Natural weathering exposure tests for automotive non-metallic materials and parts (English PDF)

6.2.2 Direct exposure device

6.2.2.1 Open exposure frame (general method)

Open exposure frame is applicable to the exposure test for exterior materials, and various shapes and dimensions of specimens. Generally, it is made of aluminum alloy.

Aluminum alloy exposure frame is suitable for different climatic regions; iron and steel materials through proper painting treatment and wood materials without any treatment are suitable for desert region; copper-nickel alloy material is suitable for high corrosive regions. Exposure frame shall have sufficient length and width to install and fix the specimens, which are ensured not to influence each other. When installing the specimen, generally use porcelain insulation folder, plastic stopper pin, wooden frame, wire and lining plate through corrosion-resistant treatment, fastening screws and etc.

6.2.2.2 Exposure frame with backplane (coating system)

Backplane can be made of metal sheet and wooden plywood. When the fixed holder is made of plywood for directly installing the specimen, if the plywood occurs obvious layering or significant fiber releasing, then it shall be replaced timely. The plywood with medium and high density covering layer is more suitable than the plywood without covering layer to work as the backplane, so that reduce the replacing times of the backplane. In the dry climatic region, the thickness of applied plywood is generally no less than 13mm; while in the subtropical or tropical climatic regions, the thickness of applied plywood is generally no more than 19mm. Use good weather-resistance paint to seal the edges of plywood to prevent the delamination.

6.2.2.3 Exposure black box (only applicable to the coating system)

more solar radiation.

6.2.4 Other exposure device (such as shelter shed, immersion box, and etc.)

Shielding exposure test indicates place the specimen under the shield structure to avoid exposing under the direct exposure effect from sun, rain, snow. Shelter shed shall be made of corrosion-resistant and weather-resistant materials, such as aluminum alloy and others. Immersion exposure test indicates immerse part or entire specimen into the test solution to expose; the immersing device shall be made of corrosion-resistant and oil proof materials, or special product chamber. The structure and dimension of these special devices shall be confirmed as per the shape and dimension of the specimen, for the benefit of the installation and operation of the specimen, or as per the customer's requirements.

6.3 Measuring equipment

6.3.1 Equipment applicable to the direct exposure test include.

a) Air temperature (daily maximum or minimum value) measuring equipment;

b) Black panel temperature (daily maximum or minimum value) measuring equipment;

c) Relative humidity (daily maximum or minimum value) measuring equipment;

d) Wetting time measuring equipment;

e) Rainfall (mm) measuring equipment;

f) Measuring equipment of the total amount of solar radiation;

g) Measuring equipment of the amount of solar ultraviolet radiation (300nm ~385nm);

h) Other (such as wind direction, wind speed, and atmospheric pressure) measuring equipment.

6.3.2 Equipment applicable to the direct exposure test under the glass include.

a) Pyranometer. It shall be installed under the glass the same as the chamber body (the same exposure angle), the measured wavelength rang is within 295nm~2800nm, record and provide the hourly amount of radiation, and time domain above accumulated amount of radiation;

b) Ultraviolet radiation intensity meter. It shall be installed under the glass the same as the chamber body (the same exposure angle), the measured wavelength rang is within 295nm~385nm, record and provide the hourly amount of radiation, and time domain above accumulated amount of radiation;

c) Air temperature measuring equipment in the test chamber;

8.1 Setting method of test period

8.1.1 In addition to specimen types, uses, and test objectives, the setting of test period shall also consider correctly mastering the aging process of the specimen. […]