Plastic Dish Rack Without Cup Holder Plastic Dish Rack Without Cup Holder,Plate Drainer,Dish Drying Rack,Plastic Dish Tray Jiangmen Jianghai Jianshang Houseware Co.,LTD. , https://www.jm-jianshang.com
Xenon weathering test chambers, whether air-cooled or water-cooled, experience a gradual decline in the output of their xenon lamps over time. To maintain consistent irradiance levels, advanced models incorporate a feedback loop control system. This system allows operators to set a desired irradiance level, while sensors inside the chamber continuously monitor the light intensity. As the lamp ages and its output weakens, the system automatically adjusts by increasing the power supplied to the lamp, ensuring stable testing conditions.
In theory, light intensity can be measured across the entire xenon spectrum, but in practice, only specific wavelength bands are typically used for irradiance control. The choice of control band depends on the material being tested and the environmental conditions it's expected to endure. For example, materials sensitive to ultraviolet (UV) radiation will require monitoring in the UV range, while others may focus on visible or near-infrared wavelengths.
The 340nm control point is one of the most widely used in accelerated aging tests. This wavelength corresponds to the short-wave UV region, which is particularly harmful to many outdoor materials like coatings, plastics, and roofing materials. A specialized UV sensor with a narrow-band filter centered at 340nm is used to monitor this area. Typical irradiance settings for this control point are around 0.35 or 0.55 W/m²/nm at 340nm.
On the other hand, the 420nm control point is commonly used when simulating indoor lighting conditions, especially when window glass filters are involved. This wavelength represents the long-wave UV and visible light range, which can cause damage to materials exposed to sunlight through windows. A filter that allows only a narrow band around 420nm is used with the sensor. The standard irradiance setting for this control point is usually 1.10 W/m²/nm at 420nm.
Most air-cooled and water-cooled xenon weathering chambers come equipped with either a 340nm or 420nm narrow-band irradiance control system. However, some European test chambers may use broadband sensors, such as TUV (300-400 nm) or full-spectrum sensors (280-800 nm). While these sensors provide a broader measurement range, they are less sensitive to small changes in the UV spectrum, which can affect the accuracy of tests involving critical degradation mechanisms driven by short-wavelength UV light.
Modern xenon weathering test chambers feature efficient, closed-loop feedback systems that help maintain precise irradiance levels. Regular replacement of the xenon lamp is recommended to minimize the impact of aging on performance. Using a sensor that controls irradiance at 340nm or 420nm further reduces spectral variations in the targeted region, ensuring more reliable and repeatable test results.