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Topic: Lamp damage

Paul G. Thompson
The Weenie Man

Posts: 4718
From: Mount Vernon WA USA
Registered: Nov 2000

posted 03-25-2001 07:55 PM

Randy, my reference is what the Osram guys told me about 20 years ago...

Randy Stankey
Film God

Posts: 6539
From: Erie, Pennsylvania
Registered: Jun 99

posted 03-25-2001 09:27 PM

The only information I have is the "ten atmospheres factoid". The rest is calculated from the gas law.

If the lamp temp. went up to 400 deg. celsius then the pressure would go up to 335.36 psi.

I guess the answer would be for somebody to take one of those infrared thermometers and take a reading off a lamp that's just been turned off from running a show. That would give a pretty close estimate of the real temperature. If we could find out the actual cold pressure inside the lamp as well, then we could calculate the real pressure.

Even if my calculations aren't quite right, I know they are in the ballpark. It's still good enough to get the point across to the "popper jockeys".

Toby Dobson
Film Handler

Posts: 1
From: Anchorage, AK, USA
Registered: Feb 2001

posted 03-26-2001 07:10 AM

I have lurked here for a while now and would like to say hello to all. I have used both Christie and ORC bulbs in both Christie and Highlight II lamp houses. I have had christie bulbs mushroom out like Randy's a few times before, but not near that bad! They will be fine one day, three days later, they have the three pimples on them. this always seemed to happen rather quick. This also never happened with ORC, it will with extended use or current problems, but never consistently at the end of it's recommended life.

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Bruce McGee
Phenomenal Film Handler

Posts: 1776
From: Asheville, NC USA... Nowhere in Particular.
Registered: Aug 1999

posted 03-26-2001 09:31 AM

How about impurities in the metal being used in the lamp?

My xenon knowledge is limited to the 350 watt Ushio lamps that my Eiki 16's use. But, recently, I was able to repair the power supply (shorted diode) after reading a post here at FT.

I've had lots of TV/Radio repair experience. I would not advise doing anything otherwise. You could get hurt.

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Darryl Spicer
Film God

Posts: 3250
From: Lexington, KY, USA
Registered: Dec 2000

posted 03-26-2001 10:56 AM

Randy, Your theories are pretty accurate. Depending on the internal tempreture of the xenon gas will determin how much preasure is on the bulb. Internal preasure can get as high as three times the preasure as when it is cold.

During manufacturing the bulb is put thru stress tests. The xenon gases are added thru the same tube the glass blower uses to form the bulb. The bulb is then cooled to a state that freezes the xenon gases into crystals. The glass blower is then able to seal off and remove the blow tube. That is why there is a nipple on the bulb. The bulb then is allowed to warm back up to room tempreture. Everything is tested at maximum for a short period of time before it is passed on to shipping.

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John Pytlak
Film God

Posts: 9987
From: Rochester, NY 14650-1922
Registered: Jan 2000

posted 03-26-2001 11:03 AM

I recall that NASA did have a training film on the proper handling of xenon lamps that did show lamps exploding in slow motion. These lamps can be just about as lethal as a hand grenade.

Here again is the link to the NASA safety manual on proper handling of xenon lamps:
http://osat.grc.nasa.gov/GSM/GSM-26.htm

------------------
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

posted 03-26-2001 11:52 AM

One of my old college buddies used to be a lab assistant for Dr. Edgerton in the Strobe Lab at MIT. In the summer during heir "IAP Session" they have a courst in super-slo-mo photography. I always wanted to take an old lamp there and have pictures taken of one exploding. It would be cool!

PS: Doc Edgerton is the guy who took those stop-motion pictures of a bullet in flight, etc. If you've ever seen the one of the drop of milk shooting up like a fountain, that's one of his too. I met him once. He was a pretty cool guy. Even by MIT standards.

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John Pytlak
Film God

Posts: 9987
From: Rochester, NY 14650-1922
Registered: Jan 2000

posted 03-26-2001 12:08 PM

Harold E. Edgerton was the "founding father" of high speed photography and super slow motion, and is on the SMPTE "Honor Roll" of distinguished pioneers in motion-picture technology:
http://web.mit.edu/edgerton/main.html
http://www.hamilton.net/Aurora/City/edger7.htm
http://web.mit.edu/newsoffice/tt/1998/sep23/edgerton.html
http://salticus-peckhamae.mit.edu/afs/athena.mit.edu/org/m/museum/exhibits/doc2.html

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Evans A Criswell
Phenomenal Film Handler

Posts: 1579
From: Huntsville, AL, USA
Registered: Mar 2000

posted 03-26-2001 01:35 PM

Somewhere at home, I have a videotape of a 1 hour show about Edgerton that I taped off PBS back in 1987. I'd love to have a better copy of that with better picture quality (I lived 100 miles from any major city at the time and reception wasn't great). The name of the show was something like "Edgerton and his incredible seeing machines" and it may have been a "Nova" show, but I'm not sure.

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John Walsh
Film God

Posts: 2490
From: Connecticut, USA, Earth, Milky Way
Registered: Oct 1999

posted 03-26-2001 02:30 PM

If it's the Edgerton documentary I saw, it was pretty good. It showed him in front of a class, demonstrating a huge strobe lamp. The lamp was used for taking military aerial reconnaissance photos at night. He held a newspaper up in front of the strobe lamp and fired off one flash. The lamp was so powerful, that even with only a 1/10 sec flash, the newspaper caught fire.

Man, there is a lotta cool stuff in this world.....

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Greg Mueller
Phenomenal Film Handler

Posts: 1687
From: Port Gamble, WA
Registered: Jun 99

posted 03-26-2001 02:52 PM

"The lamp was so powerful, that even with only a 1/10 sec flash,the newspaper caught fire."

Good Lord!
What kind of electronics did he use to juice it with? What kind of lamp?

------------------
Greg Mueller
Amateur Astronomer, Machinist, Filmnut

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John Walsh
Film God

Posts: 2490
From: Connecticut, USA, Earth, Milky Way
Registered: Oct 1999

posted 03-26-2001 03:12 PM

They didn't say what electronics were used. If I remember, he was expaining that this lamp was used for the military during WW2, yet the documentary was shot much later. So, even though this bulb was that powerful, it was something like 30 year-old techonolgy.

The bulb was in a reflector- about the same size as a 4000 watt film lamphouse reflector. The newspaper was taped to a yardstick, held about 1 foot in front. I imagine the black printing on the paper helped it ignite. It was weird how there was a slight delay after the light went off... then the newspaper burst into flames.

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