Film-Tech Forum ARCHIVE: Xenon lamp cooling

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Posted by Josh Jones (Member # 447) on 04-25-2001, 10:03 PM:

here is the scoop...
I have a Kniesley L-100-3 lamphouse that I recently acquired. I ran it for a 3 hour period one night and the room became quite warm. would it be safe to flip the exhaust blower around so that it blows air out instead of in? I want to run the hot air up a hose and out of the room. A friend of mine I talked to said that should be ok so long as you blow a little air over the ends of the bulb, but never on the glass. A vision of a big muffin fan blowing on the cathode and reflector comes to mind.
what do you think?

Josh

Posted by Michael Cunningham (Member # 210) on 04-25-2001, 10:11 PM:

Um, I think your friend is a little off, unless I'm not understanding something... The way lamphouse cooling is supposed to work is that air is pulled from the booth, travels all around the bulb, and then is sucked out of the top of the lamphouse and exhausted to the roof. My Strong lamphouses have a top-mounted blower that pulls air down from the booth just behind the refelector where it travels throught the center hole, around the bulb. It also has an intake fan at the front which blows cool air onto the front of the bulb. Hot air is then piped to the roof through a vent rising from the center of the lamphouse, just above the center of the bulb. Hope this helps you.

-Mike

Posted by John Walsh (Member # 168) on 04-25-2001, 10:19 PM:

I would not advise doing that. Usually the air flow has been designed to go in a certain direction. Besides, do you really want to have to modify the lamphouse with a muffen fan? I assume the lamp is so small that there's not top exhaust.

Is there an air vent somewhere in the lamphouse? Maybe you could adapt a hose to fit there. Old lamps used to have a sort of large, upside funnel above them to gather heat and vent it outside.

Posted by Josh Jones (Member # 447) on 04-25-2001, 10:24 PM:

This is a 500 watt Kniesley l-100-3 lamphouse. It seams safe to me because the bulb never had any airflow on it before, and the only parts that were really air cooled were the reflector and the cathode stud. Besides, this way wont natural convection aid a little too? before air entered the top and exited the bottom, opposing natural convection. It was designed this way, but wouldn't my way run cooler?

Josh

Posted by Aaron Sisemore (Member # 145) on 04-25-2001, 10:49 PM:

You may also want to be concerned about running lamps not exhausted to the outside as some xenon bulbs can generate ozone in operation and its toxic when concentrated. Additionally, bulb life is lengthened greatly if the lamp is properly cooled and exhausted.

Aaron

Posted by Paul G. Thompson (Member # 655) on 04-26-2001, 01:47 AM:

Josh, John is right. So is Aaron about the exhaust.

Posted by Scott Norwood (Member # 30) on 04-26-2001, 07:52 AM:

Is outside exhaust really an issue with the smaller xenon lamps? I would think that it wouldn't be a major issue with 1kw and smaller. I never had a problem with heat or (I hope) ozone when running two 1kw 16mm projectors in a smallish booth, with no outside exhaust.

Posted by Jeff Taylor (Member # 443) on 04-26-2001, 08:06 AM:

IMHO, Scott's right. I know even "Ozone Free" xenon's generate some, but let's face it, LOTS of people run 500-550 watt xenons in portable machines with no outside venting. Furthermore, from what I've seen the forced cooling on these short arc horizontals is really directed at the anode and cathode and not "blanket cooling" of the entire envalope. Obviously the lamp and lamphouse manufacturers know best (I hope), but in this size range I don't think it's all that much of a problem.

Posted by John Pytlak (Member # 331) on 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

Posted by Randy Stankey (Member # 64) on 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.)

Posted by John Pytlak (Member # 331) on 04-26-2001, 09:18 AM:

Excessive or uneven cooling of the lamp can cause arc instabilities (flicker) and deposits to build up on the cooler areas of the quartz envelope of the lamp. Follow the lamphouse manufacturer's recommendations regarding venting. Keep all air intakes to the lamphouse clean and clear, and be careful not to misposition any baffles or ducts within the lamphouse.

Posted by Scott Norwood (Member # 30) on 04-26-2001, 10:52 AM:

What does ozone smell like? Is it the same kind of smell that is produced by xerox machines and laser printers (which also produce ozone)? If so, then I certainly didn't have any problems with it, even when running two 1kw lamps (probably the "ozone free" type) in a not-very-well-ventilated booth. I'm sure that lamp life probably would have been helped by better ventilation, but I wasn't in a position to make that decision.

Posted by Aaron Sisemore (Member # 145) on 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

Posted by John Pytlak (Member # 331) on 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 ).

Posted by Tom Sauter (Member # 616) on 04-26-2001, 12:36 PM:

Scott: all Eiki xenon lamps are listed as ozone-free so you can relax

That "copier smell" is ozone. Another way to smell it distinctly is to run your hand along the front of your TV while its on. You'll feel yourself pick up static, and after covering the entire screen you'll smell it on your hand.

The last time I smelled ozone after a thunderstorm was when lighting hit my house!

Posted by Jerry Chase (Member # 660) on 04-26-2001, 01:12 PM:

Burnt mustiness is an appropriate metaphor. That is exactly what the ozone is doing, "burning" or oxidizing the dust and mold in the air. I'm not sure that the actual pure ozone has an odor as much as an acrid sensation. I can verify the effects though. Most of the time when I visited the radio station (another ozone generator) as a kid, I'd smell the difference in the air and get a headache.

If trying John's transformer trick, keep one hand behind your back. I'm sure this goes without saying to the active participants, but you never know who could be lurking.

One of the _absolute dumbest_ tricks I ever heard of anyone pulling was one female projectionist, who decided that she looked a little pale and the xenon lamp would give her a quick tan. She got away with it, but she was the one who later had the low power bulb explode on her. I only learned of her "tanning booth" after the bulb explosion. Some people are accidents waiting to happen.

Posted by John Pytlak (Member # 331) on 04-26-2001, 01:46 PM:

Unprotected viewing of a xenon or carbon arc, even for a few seconds, is likely to permanently damage your eyes.

If you're lucky, you'll see the after-image of the arc that was burned into your retinas for the rest of your life. If you're unlucky, you could lose your eyesight entirely. NEVER open the lamphouse while the lamp is lit (or hot), and NEVER look directly into the "business end" (lens) of the running projector.

Posted by Gordon McLeod (Member # 33) on 04-26-2001, 08:05 PM:

Ozone is an unstable molicule it is O3
All Xenon lmaphouses produce some ozone on ignition from the spark gap. Even with Ozone free lamps
Some of the smaller compact ignitors have seal sparkgaps that help prevent ozone generation
I remember working in a small 5 screen booth with 700 watt lamps that were vented into the room and the lingering smell of ozone for about 1/2 after all 5 shows started
Small amounts of Ozone are helpfull as an air purifer

Posted by Chris Erwin (Member # 176) on 04-26-2001, 09:27 PM:

Ozone....memories of model train transformers come to mind. Some of the older ones...whoa, you get a whiff of ozone.

When I was really young, I just thought it was just a added feature of the train. (realistic smell choo-choo)

I'd figure a way to at least vent it away from the immediate operating area. (Dryer hose?) I've seen some places run the vent to the attic, or others into/through a wall. At 500w and you're not running a daily grind (4 or more shows per day) you shouldn't have any big problem...but it's a good way to save $$$ on lamps.

--Chris

Posted by Randy Stankey (Member # 64) on 04-27-2001, 01:11 AM:

I would describe the smell of ozone as that "electricity smell" you get after a good lightning storm.

I had a General Manager who opened the lamphouse door. The lamp failed during the show and he came running into the booth and opened her right up. Tha lamphouse hadn't even been off for a minute. The projectionist on duty was already at the machine. When that clown opened the door he just ran the other way! (I found out about this the next morning after it happened.)

When people ask me how bright the xenon lamp is I tell them, "Well I don't know for sure, I've never actually looked at it. That's why I'm not blind."
Kidding aside; I have always told people that it's something like ten times brighter than looking at the sun. Then I tell them that it's so bright that if you look at it (without protection) that you'll be blind even before you "see" the light... you'll just look in and the next thing you'll notice is that you can't see anymore.

Posted by Bernard Tonks (Member # 809) on 04-28-2001, 07:49 AM:

30 years ago I did a days relief projection at the old Classic Kilburn when xenon bulbs were not ozone free. The smell was most putrid and I did suffer from severe headache. How the chief operator coped with this I never did find out. I know I was glad to get back to my own show with Peerless carbon arcs.

Worthing beach in the UK can be extremely bad from ozone with the seaweed, the sort of place to go if you want the experience, and maybe good for your health as it is by the sea ?

I changed to xenons 19 years ago, first 1.6k, now 2k. Can someone please tell me the year ozone free lamps were first introduced, and was this a health and safety issue.

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Posted by Jan Hackett (Member # 1231) on 06-04-2002, 01:08 PM:

HELP... I am smelling a pungent odor in my booth right now. Is it my superior quartz bulb 7kw bulb leaking.?????

------------------
Jan Hackett
Theater Operations Manager
Extreme Screen Dynatheater
NM Museum of Natural History Foundation

Posted by John Pytlak (Member # 331) on 06-04-2002, 01:42 PM:

Jan said: "HELP... I am smelling a pungent odor in my booth right now. Is it my superior quartz bulb 7kw bulb leaking.?????"

AFAIK, xenon gas is odorless and would not have a "pungent" odor.

Here is an MSDS:
http://www.praxair.com/praxair.nsf/0/85a2707fb21e443c85256a86008221b2/$FILE/P4677C.pdf

Anyway, loss of xenon pressure would quickly cause lamp failure.

The odor may be ozone. In a xenon lamphouse, ozone may be generated by high voltage "corona" discharge (lamp ignition system) or by breakdown of oxygen molecules by intense ultraviolet energy from the lamp (not using an "ozone free" lamp that has additives to the quartz envelope to reduce ultraviolet energy). Are your lamps well vented to the outside?

Pungent odors could also be caused by excessive heating or burning of materials, such as plastic wire insulation. Obviously you need to find the source.

I assume you are familiar with the characteristic "pungent" odor of prints "rejuvenated" with UV-cured overcoats?

------------------
John P. Pytlak, Senior Technical Specialist
Worldwide Technical Services, Entertainment Imaging
Research Labs, Building 69, Room 7525A
Rochester, New York, 14650-1922 USA
Tel: +1 585 477 5325 Cell: +1 585 781 4036 Fax: +1 585 722 7243
e-mail: john.pytlak@kodak.com
Web site: http://www.kodak.com/go/motion

Posted by Frank Angel (Member # 248) on 06-05-2002, 05:02 AM:

But isn't ozone supposed to be a kind of air purifier? or disinfectant? I remember they used to sell these devices that had untraviolet bulbs in them and a small fan and supposidely this "cleaned" the air. I remember the hype on the box saying just what Tom said about the thunderstorm -- "You can smell the freshness it brings to the room because it smells just like country air after a thunderstorm." I always thought it was a good thing. Like it's bad when we deplete it, as in the hole in the ozone layer. Or am I confusing it with something else?

Posted by John Pytlak (Member # 331) on 06-05-2002, 06:11 AM:

Although upper atmosphere ozone helps protect the earth from excessive ultraviolet radiation, high levels of ozone at ground level are harmful to the health. Ozone is a major component of "smog" that pollutes the air of major cities.

Here is something I found on the Internet:

"OSHA regulates employee exposure to ozone gas through its Air Contaminants Standard, 29 CFR 1910.1000. The permissible exposure limit (PEL) is listed in Table Z-1 as an 8-hour, time-weighted average value of 0.1 part of ozone per million parts of air (ppm). Rule 29 CFR 1910.1000(e) requires that administrative or engineering controls must first be identified and implemented whenever feasible to achieve compliance with the PEL. When such controls are not feasible to achieve compliance, personal protective equipment, respirators, or any other protective measures shall be used to keep the exposure of employees to ozone gas within the PEL."
http://www.kesmist.com/oz1.htm

Here's the EPA word on ozone "air purifiers":
http://www.epa.gov/iaq/pubs/ozonegen.html

Health Canada agrees:
http://www.odatus.com/doc70.html

Posted by Brian Tristam Williams (Member # 1235) on 06-05-2002, 12:34 PM:

Just as I was about to ask, I read John's response. For ten years or more now, I've wondered if this was ozone, and I've just gotten my answer: A friend and I were having a look at a black-and-white TV that had lost its vertical retrace. While looking at the PCB, I accidentally touched the insulation on the cable from the flyback transformer to the tube. A purple plasma-like 'aura' glow connected my fingertip to the wire when my hand was an inch or so from the wire, but there was no touch sensation to it, and there definitely was a scent involved.

For some reason, I always thought that that must be ozone. As to whoever asked if their lamp was 'leaking', I don't think that ozone is something within the lamp that can leak out. It is something that is created, externally to the lamp.

[Edited because I read the answer in John's .PDF link. Xenon is not toxic, a gas, and almost totally inert, is the answer I sought.]

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"One man can make a difference."