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This topic comprises 2 pages: 1 2
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Author
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Topic: Xenon lamp cooling
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John Pytlak
Film God
Posts: 9987
From: Rochester, NY 14650-1922
Registered: Jan 2000
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posted 04-26-2001 08:33 AM
In a xenon lamp, ozone can be generated by the high voltage ignition (corona ionization) and by strong UV (ultraviolet) radiation breaking down oxygen molecules. "Ozone Free" xenon lamps have special additives in the quartz bulb to reduce the amount of short UV radiation, but still can produce some ozone. When you first come into a room where there is ozone, the pungent odor is unmistakable. (The nose is very sensitive to the smell of ozone). After breathing it for a while, you become desensitized and may not notice it anymore, but may have side-effects like a headache, sinus pain, or eye irritation. If there is enough ozone to notice the odor, better ventilation is needed. Ozone is good in the upper atmosphere because it helps shield the earth from excess ultraviolet radiation, but it is NOT good to breathe it. ------------------ John P. Pytlak, Senior Technical Specialist Worldwide Technical Services, Entertainment Imaging Eastman Kodak Company Research Labs, Building 69, Room 7419 Rochester, New York, 14650-1922 USA Tel: 716-477-5325 Cell: 716-781-4036 Fax: 716-722-7243 E-Mail: john.pytlak@kodak.com Web site: http://www.kodak.com/go/motion
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Randy Stankey
Film God
Posts: 6539
From: Erie, Pennsylvania
Registered: Jun 99
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posted 04-26-2001 09:03 AM
I 'd say that it's possible to OVER ventillate a lamphouse.I have been told that it's not a good idea to open the lamphouse right after running the lamp. The idea is that the rush of cold air can cause the lamp to crack and break. (Thermal shock) It then follows that if there's too much cool air comming into the lamphouse because you've beefed up the fans, you could cause the same thing to happen. I vote for leaving the lamphouse as it is and just getting some outside ventillation in the room. Maybe just some kind of exhaust fan? The booth at the college I worked at had an exhaust for the lamphouse itself AND an exhaust fan hooked up to a thermostat. The room is also used as a follow spot booth during stage shows. (Yes, they were carbon arc.)
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Aaron Sisemore
Flaming Ribs beat Reeses Peanut Butter Cups any day!
Posts: 3061
From: Rockwall TX USA
Registered: Sep 1999
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posted 04-26-2001 11:28 AM
Randy: why would ANYONE want to open a xenon lamphouse up right after turning it off? even in the most heinous of emergencies, i would wait at least ten minutes for the bulb to cool before even thinking of opening the door(s) to access the lamp.The only time I have seen a problem with there being too much ventilation to the point of affecting lamphouse operation was in one location with a CFS console that had its main cooling blower sieze (the one in the rear that is ducted directly to the bulb) and the exhaust was so good that the vane switch that normally cut the power when the fan stops was being held closed by the exhaust alone! Scott: its difficult to describe but ozone smells a little like a 'burnt mustiness' and is unmistakeable once you get a good whiff of the stuff. Malfunctioning neon gives off quite a bit of ozone as well, that is where I have received the best idea of what it smells like, especially when the neon is indoors and the ozone ends up in the projection booth :O Aaron
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John Pytlak
Film God
Posts: 9987
From: Rochester, NY 14650-1922
Registered: Jan 2000
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posted 04-26-2001 11:40 AM
Scott: Yes, the high voltages used to attract the toner in electrostatic copiers and laser printers do generate ozone. Likewise any AC corona discharge, as around an old TV high-voltage flyback transformer or neon sign. Sometimes, you can smell it outside during a lightning storm. If you ever built a Van De Graaf generator, Tesla Coil, Jacob's Ladder, or other high voltage electricity demonstrator for a science fair, you've probably smelled ozone."Mr. Wizard" says you can easily generate ozone by CAREFULLY (we're talking THOUSANDS of lethal volts here ) bringing the output leads of a neon transformer close together, until there is a corona discharge or "St. Elmo's Fire" between the two leads (be careful not to let an actual spark jump between the leads). The pungent smell of ozone will live in your mind forever! (But don't accidently kill yourself doing this experiment ). ------------------ John P. Pytlak, Senior Technical Specialist Worldwide Technical Services, Entertainment Imaging Eastman Kodak Company Research Labs, Building 69, Room 7419 Rochester, New York, 14650-1922 USA Tel: 716-477-5325 Cell: 716-781-4036 Fax: 716-722-7243 E-Mail: john.pytlak@kodak.com Web site: http://www.kodak.com/go/motion
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