400W mercury vapour blacklight

[@psirvent8]

Hello, Just out of curiosity did you protect your eyes during the video ? I also have a 400W mercury vapour blacklight and always put my ski goggles on before firing it up as it will otherwise cause me eyestrain and probably a cataract or macular degeneration later on.

[@lunchie80]

Fun fact, glass knocks UV transmission down a fair bit. Nearly all of UVB(not a huge issue here) and about 25% of UVA. So you're reducing output by a good 25%. Pro 400w UV cannons have mesh but no glass in the front for this reason.

[@psirvent8]

Since the lightbulb itself is made of glass it should already block all the UVB and most importantly UVC rays coming from the mercury arc tube and that will cause arc flash in seconds as well as ozone to form if they were allowed to pass through the bulb. UVA on the other hand isn't blocked by glass, which explains why white plastics turn yellow from sunlight behind windows as wallpapers and paintings fade over time for the same reason. I think the mesh instead of a window in front of blacklight cannons to allow the tremendous amount of heat the lamp produces to be more easily dissipated. Blacklight mercury vapor lamps actually run hotter than white ones meant for lighting gyms and warehouses because the dark purple glass not only gets hot from the infrared radiation coming off the arc tube but also from all the absorbed visible light as well.

[@Sparky-ww5re]

​@@psirvent8I have a BT37 400 watt mercury vapor blacklight that I use in a Hang-A-Light made by SouthWire, 400 watt PSMH ballast with ignitor disconnected. I mostly use it during Halloween week for the haunted house setup in the polebarn, and sometimes while hosting night time parties, and I can confirm it gets extremely hot, definitely hotter than the clear metal halide, which I used to use for temporary lighting on construction sites before I invested in a bunch of LED work lights with part of my end of the year bonus a couple years back.