When purchasing cables, ensuring that the sheath materials can maintain their integrity under ultraviolet (UV) radiation is crucial. This guide provides a straightforward overview of the UV resistance test based on ISO 4892-2 and ISO 4892-3 standards.
Purpose
This test evaluates the ability of cable sheath materials to withstand UV radiation from sunlight or fluorescent light. It assesses the retention of tensile strength and elongation in the sheath of cable samples after UV exposure.
Sample Preparation
Prepare six test specimens and six control specimens according to the applicable ISO 4892-2 or ISO 4892-3 standard.
Equipment
Use the UV exposure apparatus as described in ISO 4892-2 or ISO 4892-3. Additionally, a tensile testing apparatus suitable for testing the sheath specimens is required.
Procedure
General Steps
Initial Measurement: Measure the tensile strength and elongation at break of the control specimens using a tensile testing machine before conditioning.
Conditioning: Prepare the test specimens as described. After exposure, test the specimens for tensile strength and elongation in the same manner as the control specimens.
For Outdoor Cables (Weatherometer Test)
Suspension: Suspend six test specimens vertically so their external surfaces are uniformly exposed to UV rays.
Testing Conditions: Maintain a black-panel or black-standard thermometer temperature of +60°C ± 3°C and a relative humidity of 50% ± 5% during dry periods.
Exposure Cycles: Cycle the specimens through periods of UV exposure and no radiation. Each cycle lasts 120 minutes: 102 minutes of dry UV exposure at +60°C ± 3°C, followed by 18 minutes of rain exposure at +50°C ± 5°C.
Duration: The test duration is 4000 hours (2000 cycles) unless specified otherwise in the relevant product standard.
Post-Exposure Conditioning: After exposure, condition the test specimens at ambient temperature for at least 16 hours. Keep the six control specimens at ambient temperature, protected from direct sunlight, and test them simultaneously with the exposed specimens.
For Indoor Cables (QUV Test)
Exposure: Follow the guidelines in ISO 4892-3. Expose the test specimens to UV radiation for a minimum of 720 hours.
Requirements
After exposure, the average tensile strength and elongation of the test specimens must be at least 80% of the original values.
Specification Details
The detailed specification should include:
The method to use: ISO 4892-2 for outdoor cables or ISO 4892-3 for indoor cables.
Any deviations in exposure conditions or duration from those specified.
Any different compliance requirements from those specified here.
By following these guidelines, you can ensure that the cables you purchase have excellent UV resistance, maintaining their performance under sunlight or fluorescent light exposure.