In the inspection of cable insulation and sheath materials, a heat aging test is commonly performed. The primary equipment used for this test is the ventilation-type aging chamber. The test temperature varies depending on the type of material being tested, typically ranging from 100°C to 200°C. While the ventilation-type aging chamber is classified as an environmental testing device, it has specific requirements that differ from general environmental testing equipment. Based on relevant regulations, standards, and practical calibration experiences, this article explores key aspects of the calibration process.
First, the measurement characteristics of the ventilation-type aging chamber include air exchange rates (8 to 20 times per hour), temperature deviation (±2°C), temperature uniformity (±2°C), and temperature fluctuation (±0.5°C). These parameters are critical for ensuring accurate and consistent test results.
Second, the calibration conditions require an ambient temperature between 15°C and 35°C, relative humidity between 30% and 85%, and atmospheric pressure between 86 kPa and 106 kPa. Calibration is usually performed under no-load conditions, but if required, it can also be done under load, provided the load is clearly specified.
Third, standard equipment and other instruments used during calibration include temperature sensors, display instruments, mercury thermometers, standard wattmeters, and stopwatches. Each instrument has specific technical requirements: the temperature sensor must be of work level I, the display instrument should have a time constant of less than 15 seconds, the mercury thermometer must be of second-class standard, the wattmeter should be of 0.5 accuracy class, and the stopwatch should have a division value of 0.1 seconds.
Proper calibration ensures that the ventilation-type aging chamber operates within acceptable tolerances, providing reliable data for evaluating the performance and durability of cable materials under thermal stress. This process is essential for maintaining quality control in the manufacturing and testing of electrical cables.
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