Film-Tech Forum ARCHIVE: Depressurizing a Xenon Bulb

This is topic Depressurizing a Xenon Bulb in forum Film Handlers' Forum at Film-Tech Forum ARCHIVE.

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Posted by Bill Enos (Member # 440) on 07-24-2002, 08:20 AM:

Is there a practical, reasonably safe way to depressurize a decommissioned bulb? Otherwise, are demo bulbs available? I had considered wrapping a dead bulb in several layers of a quilted moving pad and drilling into one of the metal ends. Somebody is bound to have tried something. Any suggestions?

Posted by Paul Konen (Member # 41) on 07-24-2002, 08:51 AM:

Do what most of us do and that is keep it in it's protective shell, tape the box closed and then accelerate it to the floor. This will cause it to explode before disposing it's contents in the dumpster.

Posted by John Pytlak (Member # 331) on 07-24-2002, 09:14 AM:

Some lamp vendors are willing to supply depressurized "duds" for demo purposes, especially for theatres using the larger sizes (e.g., IMAX theatres) that have booth "show and tells".

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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 Jeff Taylor (Member # 443) on 07-24-2002, 09:40 AM:

A major exhibitor chain I work with has a deal with their suppliers where booth personnel are supposed to box 'em up and send them back. In reality the duds sit in a cabinet until someone gets brave and decides to play 4th of July in an empty dumpster with them.

Posted by Randy Stankey (Member # 64) on 07-24-2002, 10:31 AM:

Usually we put them back in the box, wrapped them up in a garbage bag and tossed them down onto the concret floor really hard. They would bust with a muted "POP!" and there would be nothing left but shattered glass and metal.

If you have a compactor style garbage dumpster at your theatre you MAY be able to put them in there and crush them. Some dumpsters don't "crush" the contents but "compress" the contents back into the larger compartment. If you have a "crush style" compactor-dumpster that would be the all-time safest way to dispose of them. All that metal enclosing the compartment would be imperviouse to even the largest xenon bulb's schrapnel.

If you want to put on a real show for yourself, take one out back to a desserted area, set one up on a tree stump and shoot it with a .22 cal. rifle from about 50 yards away. It's quite spectacular!
If you do this, take all appropriate firearms safety measures as well as all appropriate xenon bulb safety measures! (I live out in the country where people are used to hearing gunfire! )
The 50 yard shooting distance has two purposes. First it's safe. No schrapnel is going to fly that far... 10 or 20 feet, maybe but not 50 yards! Second, it's a more "manly" distance to shoot from.

I have been planning to make a movie about exploding xenon bulbs for some time, now. I'll put the camera behind a plexiglass shield, inside a wooden box and explode them in various interesting ways.
Considering the questions I've seen here over the years, I think I'll also include a segment on "safe" ways of destroying them.

What do y'all think?

Posted by John Pytlak (Member # 331) on 07-24-2002, 10:35 AM:

The original question was how do get a depressurized lamp for "show and tell".

Posted by Adam Martin (Member # 641) on 07-24-2002, 11:19 AM:

Gordon has a degassed 30K (!) lamp at Cinesphere. Something about liquid nitrogen at the local university ...

Posted by Randy Stankey (Member # 64) on 07-24-2002, 05:01 PM:

Honestly, I never considered letting the gas out of a xenon but keeping the rest of it intact.

Really, the only thing I can think of would be to freeze the lamp extremely cold. Liquid nitrogen would be the ultimate thing to use but I wonder if dry ice would be good enough.

Once it's sufficiently cold then I would think breaking off the "nipple" on the side of the bulb where the gas was put in.

Posted by Andy Muirhead (Member # 712) on 07-24-2002, 06:20 PM:

A few months ago we built a permanent display in our foyer with various old projection equipment, including a fully working 1950's Ross projector (it actually runs film, theres a red button for customers to press and it starts up and projects some trailers onto a small screen for about 10 seconds!)

Anyway we wanted some safe Xenon bulbs for the display, phoned our bulb distributor and they sent us 3 depressurised bulbs, a 1.6kw 2kw and 7kw. I don't know how they depressurise them but as Randy said previously the hole was in the 'nipple'

Posted by Gordon McLeod (Member # 33) on 07-25-2002, 07:33 PM:

The way that lamp was degassed it was submerged in to a tank of liquid nitrogen for a period of time and then the evacuation tit was sheared off and then it was slowly raised up out of the tank

Posted by John Moriarty (Member # 1153) on 07-26-2002, 02:26 PM:

Andy said:

quote:
I don't know how they depressurise them but as Randy said previously the hole was in the 'nipple'

Surely, it would make more sense for manufacturers just to omit to pressurise the bulb than go to the trouble of pressurising it and then depressurising it. Perhaps even they could use bulbs they don't pressurise for a reason (e.g. manufacturing fault with components).

John

Posted by Pete Naples (Member # 761) on 07-26-2002, 03:38 PM:

Andy that sounds quite interesting, I must pop in to your place and take a look the next time I'm passing.

One place I refurbushed were toying with the idea of doing something similar with a 35/70 Fedi XT. It sat in the foyer after being dragged outta the booth but simply took up too much room.

At one point the GFT were going to put one of their retiring DP70's on display, I don't know if they ever did.

Posted by Chad Souder (Member # 343) on 07-26-2002, 09:24 PM:

This is a piece of cake. I have done several of these for parting gifts for long-time projectionists of mine. Here's a basic step-by-step of what I do:

1. Put the bulb in whatever case it originally came in (although this may be sufficient, I tape a newspaper over it as well just to be on the safe side, leaving a space in the paper through which to drill).

2. With proper face and hand protection on, clamp the bulb into a vice or similar sturdy holder.

3. Get yourself a small bit from the hardware store that is sold for the specific purpose of glass and tile. I can't remember what size I bought, but it's quite small.

4. Drill through the plastic case into a part of the glass that is not rounded. Most bulbs I think are curved around the points, and then they straighten out for an inch or two before getting to the metal. This straight part is where you want to drill. Drill very slow, with little pressure, and take frequent breaks to allow the bit to cool. Do NOT push with much pressure, let the weight of the drill do the work.

5. As you drill, you will be able to see a divot forming in the glass. Eventually, when you finally drill through, you will see the glass shavings puff away as the air escapes. I would think that the older the bulb, the less pressure is left, but maybe not. When finished, you can see a tiny hole through the glass, and you will be left with a completely safe conversation piece. I usually leave the bulb in the case and then make some sort of pedestal out of whatever, and write the dates they worked on the pedestal. It makes a unique gift, that's for sure. If you want a picture, I could probably scrounge one up.

As a side note, I have never had one explode on me, and I have made 3 for different people, using a 1600w twice, and a 3000w once.

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"Asleep at the switch? I wasn't asleep, I was drunk!" - Homer Simpson

Posted by John Anastasio (Member # 607) on 07-27-2002, 06:20 AM:

Extreme low temperature is the key to how the lamps are originally pressurized. The xenon is introduced into the lamp in a frozen, solid form as a small "pellet". The lamp is quickly sealed and as the xenon sublimates back into a gaseous form, it pressurizes the lamp.

Posted by Aaron Sisemore (Member # 145) on 07-27-2002, 12:51 PM:

FWIW, I have a nice velvet-lined plexiglass case with several inert 'display' bulbs ranging in size from 150W to 3000W (there was a 4K in there too, but it broke in transit when I got the case)... I think Brad has a pic of them around here somewhere...

-Aaron

Posted by Mike Williams (Member # 1140) on 07-30-2002, 09:33 AM:

Chad,
If you were to depressurize a bulb at room temperature like that, wouldn't it cloud up?

Or is it that bulbs that have seal failures only cloud up because of the extreme heat produced by the arc?

Posted by Adam Martin (Member # 641) on 07-30-2002, 10:12 AM:

I think the clouding is a tungsten oxide formed when the super-heated tungsten cathode and anode react with oxygen. Sometimes it's white and sometimes blue, depending on how many oxygen molecules the tungsten molecules pick up.

Posted by Dave Macaulay (Member # 813) on 07-30-2002, 09:20 PM:

Ther are a few ways to depressurize the lapm. I'd never thought of drilling one though!
At Imax I used to depressurize 15kW water cooled lamps. The procedure was to put on the blast gear, evacuate the machine shop, and with the bare bulb wrapped in another "flak jacket" so the nipple sticks out, gently introduce said nipple to the fine grindstone wheel.
I had one blow up out of about 10, it really wasn't terrifically dramatic.
When it works properly the gas just hisses out.
There was no fogging or discoloration caused by the degassing.
Unfortunately we found that used lamps that have been depressurized tend to just shatter after a few minutes to a few years.Internal stress in the envelope causes it to shatter into tiny pieces similar to breaking a car door window.

Posted by Chad Souder (Member # 343) on 07-30-2002, 10:57 PM:

Don't know much about the science part of it, but I do know that the bulbs didn't cloud up. As far as I know, the bulbs didn't shatter either, but I'll have to check with the recipients for that.

Posted by Frank Angel (Member # 248) on 07-31-2002, 01:55 AM:

Chad,

That sure takes a set. You could wrap that thing in a mattress and there would be no way I would have the nerve to stand there and drill a hole in one. I mean, you might tell me a hundred times it won't explode, but man, I would wuss out on you every time. See....that's me handing the drill to the assistant manager and running to the parking lot, yelling behind me -- "Yah, kid, just drill into that bulb; take your time."

Posted by Dennis J. Losco (Member # 1374) on 07-31-2002, 07:35 AM:

If anybody is interested in display lamps please let me know, especially if you are using the Superior lamp. We can depresurize one of yours or send you one that has been returned for disposal. My suggestion is "don't do this at home". We have sizes from 150watt to 32,000 watt lamps available.
Thanks, Denny
denjr@sqpuv.com www.sqpuv.com

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Posted by Stephen Furley (Member # 1277) on 07-31-2002, 10:13 AM:

"We have sizes from 150watt to 32,000 watt lamps available"

What would you use a 32k lamp for? Can't be for film projectors, surely; searchlights maybe, or something similar? How big are they? Can I stand a long way away when you strike one? Can I stand even further away if someone tries drilling a hole in one!

Posted by Dennis J. Losco (Member # 1374) on 07-31-2002, 10:38 AM:

32,000 watt lamps are used by the government for solar simulation. They actually have 16 to 30 of these lamps burning at the same time, all focusing down to one beam which enters a vaccum chamber. They will then test precious metels etc. for space. The lamp is pretty much the same size as a 15kw used for the IMAX projectors. We have a safe mean of depressurizing these lamps but I wouldn't suggest drilling one of these lamps at home. It would make a really loud boom!!! I can email you pictures if you would like. Quick send me an email and I will send them to you.
Thanks,
Denny

------------------
Dennis J. Losco Jr
Superior Quartz Products, Inc.
404 County Road 519
Phillipsburg, NJ 08865
denjr@sqpuv.com http://www.sqpuv.com
Tele: 908-454-1700
Fax 908-454-4154

Posted by Paul G. Thompson (Member # 655) on 07-31-2002, 08:04 PM:

Dennis says "Don't do this at home." I recommend you heed to his advice.

Posted by Stephen Furley (Member # 1277) on 08-01-2002, 06:07 AM:

"Dennis says "Don't do this at home." I recommend you heed to his advice."

I'm about 6,000km away, and I think that's about as close as I would want to get to one of those things! I was in NJ just a few months ago, I don't think I would have wanted to get that close if I'd known they had things like that there

Dennis, is that thing water cooled, it looks like it has a double skin?

I,ve just had an evil thought; you could connect one of those things up in a room somewhere, wire up the control circuits to a normal light switch. You could give someone a heck of a shock when they turned the lights on!

The brightest lamp I have seen is a 18k HMI, how does this compare to that for light output?

Posted by David Rigby (Member # 1301) on 08-01-2002, 06:13 AM:

So I'm guessing the rectifier for those 32 bulbs isn't all that portable then?

David

Posted by Bernard Tonks (Member # 809) on 08-01-2002, 06:55 AM:

All very interesting Dennis, and the pictures.

Is it possible for you to tell us the average life of the 32kw bulb, and the cost. Also a 15kw used for Imax, as I have often wondered. Thanks.

Posted by Dennis J. Losco (Member # 1374) on 08-01-2002, 07:31 AM:

Yes, this is a liquid cooled lamp. Currently we manufacture a 12,15, 20 and a 32kw. And to give you an idea of how bright they are, the next time you see pictures of the space shuttle keep in mind that our 20 kw lamps are used to illuminate it. Recently they have been swaping them out for 10kw air cooled lamps though, but they have been giving up life. The 15kw lamps will last anywhere from 1000 hours to 1500 hours and the 32kw will last about 400-500 hours. Pricing!!!!! Well lets say they begin at $5600 each for the 15's and as much as $7000 for the 32's. All of this technology was gained when we purchased the liquid cooled division of Durotest. Yea it has been really exciting and really went nice with our xenon cinema line of air cooled lamps. Hey thanks for the interest guys!!
Denny

------------------
Dennis J. Losco Jr
Superior Quartz Products, Inc.
404 County Road 519
Phillipsburg, NJ 08865
denjr@sqpuv.com
http://www.sqpuv.com
Tele: 908-454-1700
Fax 908-454-4154