How many hours of aging inside a UV aging tester is comparable to how long outdoor exposure takes?
1. This is a seemingly simple question with a complex answer. Theoretically, we cannot get a simple figure and multiply it with the test time of the UV weathering chamber to get the time of outdoor exposure. The reason for this is not that we have not developed a better UV weathering tester, but that no matter how advanced and expensive your UV weathering tester is, you still cannot find this figure. In fact, the big problem is that the outdoor exposure environment is complex and variable. Test times and outdoor exposure times in the chamber are related to the following factors.
2. The geographical latitude of the outdoor exposure site (the closer you are to the equator, the stronger the UV rays).
3. altitude (higher altitude means stronger UV rays)
4. the local geography, e.g. wind speed can affect the degree of air-drying of test samples or proximity to water sources can promote the formation of dew.
5. the weather in the same area may affect the sample twice as much as the previous year, as the climate varies from year to year
6. the effect of the season, for example, winter exposure has only 1/7 the damaging effect of summer
7. the orientation of the sample (5 degrees to the south is very different from due north)
8. Insulation of the sample (outdoor samples on an insulating carrier usually age 50% faster than those not on an insulating carrier)
9. the test cycle of the chamber (irradiation time and humidity time)
10. The operating temperature of the chamber (the higher the temperature, the faster the ageing)
Testing of special materials
Spectral distribution of laboratory light sources (SPD)
It is therefore logically meaningless to talk about the conversion factor between the artificially accelerated ageing time and the length of outdoor exposure. The reason for this is that one is a fairly constant environment, while the other is highly variable. Finding a conversion factor between the two is beyond the scope of variation.
In other words, weather data is relative data.
However, you can still get weathering test data from artificial accelerated weathering tests. But you have to recognise that that data is relative data, not data. The reliable data you get from laboratory tests is the relative rating of the material under test compared to other materials in terms of ageing
Can I put the UVA-340 lamp on one side of the QUV test chamber and the UVB-313 EL lamp on the other side?
A: Only the same type of lamp should be used in the QUV chamber for testing. Placing different lamps in the QUV at the same time will cause the UV light to interfere with each other on the sample. A small amount of UV light is reflected from each lamp in the back panel of the chamber and shone onto another sympathetic sample.
Because outdoor light is not only seasonal and geographically dependent, it is also closely related to temperature. The altitude varies from place to place and the light varies from season to season. So we can only estimate roughly.
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