Film-Tech Forum ARCHIVE: Xenon Bulbs Exploding after about 1200 Hours

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Posted by Cary Neumann (Member # 1665) on 06-11-2003, 03:17 AM:

I have had problems the last few months with Xenon bulbs( 2 different manufacturers) exploding after about 1200 hours in 2 of our 6 lamphouses.
2 Bulbs in each of the 2 lamphouses.
Any ideas on what might be happening?
Thanks, CARY

Posted by Mike Pennell (Member # 1692) on 06-11-2003, 03:49 AM:

Are the blowers and the exhaust working properly? The squirrel cages get pretty cruddy sometimes. Fingerprints on bulbs? Are you letting the bulbs cool down long enough at the end of the nite before the power is turned off?

Posted by Andrew Duggan (Member # 1302) on 06-11-2003, 03:53 AM:

Hey Cary. Do you have any more information about this problem that you can provide? What kind of lamphouses and power supplies are being used? What kind of bulbs were these, both manufacturer and power rating (1600 watts, 2000 watts, etc.)? Did you take any actions since then, like opening the lamphouse with a multimeter to check and see if maybe you're running too much power to the bulb(s)? Any more info you can throw out there will probably help a lot in figuring out the problem.

It's a bit of a shot in the dark right now, but I'm going to go out on a limb and say that either
A)You are running too much current to the bulb (you should open up your lamphouse and test this manually with a decent ammeter, since many of the built-in meters on lamphouses are notorious for being horribly, terribly wrong....Lumex...I am looking in your direction...) or
B) The ventilation on your lamphouses is inadequate (Another baleful stare at Lumex...).

These are both easy problems to remedy, but like I said they are both just blind assumptions, and as we all know, assumption is the mother of all f*ckups...

Hope this helps a bit.

Posted by Dick Vaughan (Member # 540) on 06-11-2003, 05:48 AM:

More importantly what type of lamp are they and what are the manufacturers recommended maximum hours?

Is 1200 hours greater than 25% over this figure?

Posted by German Marin (Member # 918) on 06-11-2003, 07:05 AM:

Important: The way it were handling before and during its installation. I've seen bulbs horrible shipping and it cause the quarz break. One day my workmate took a lamp because he'd go to a booth to change it and sudendly it explode (It was lying on the desk). The bulbs explodes during it were running? or at night while nobody's there?

Posted by Randy Stankey (Member # 64) on 06-11-2003, 10:58 AM:

Let's assume that nothing visible has changed in your lamphouse. Nobody had tinkered with the current taps. Nobody is mis-installing or mis-handling the lamps. You do everything the way you used to do it, only now the lamps explode.

The VERY first thing I would do is check ALL of your ventillation pipes, inlets and outlets to make sure everything's working correctly. Check out your roof ventillator to see if it's running. Check the blower inside (or that blows inside) the lamphouse. Make sure all the duct work isn't clogged up with dust bunnies. Make sure that no birds have come along and built a nest in your ventillation pipes that go up to the roof.

Check the air flow to see if there is an air stream blowing right on (or right near) the lamp itself. Compare the results of the "suspect" lamphouse with the results of a test on an identical "known-good" lamphouse if you can.

I KNOW somebody is going to holler for this suggestion but here goes...

A lit cigarette makes a good "air flow tracker". When held near the exhaust duct, the smoke should almost instantly get sucked out and none of it should linger inside the cavity.

If you don't like the idea of cigarettes in your booth, even for the short time it takes you to do this test (then you put the cigarette out and throw it in the trash) you can use a candle or a wooden match. Just light it and let it burn for a short time then blow it out. It will produce 10 - 15 seconds worth of smoke that you can do the test with.

One dead give away that your lamps are overheating is when you look at the metal ends of the lamp that are left over after the explosion. IF they are darkened or even "rainbow" colored (Blue and yellow and orange, etc.) you KNOW that the lamp it getting too hot. The first likely cause of that is lack of ventillation. The second likely cause of that is putting too much current through them.

Like I said, though, I'm assuming that everything in your equipment looks the same as it was before and nobody has been tinkering. That puts the "too much current" theory into second place. Check your ventillation first and then check other things.

Posted by Tom Sauter (Member # 616) on 06-13-2003, 10:31 AM:

A third cause of overheating discoloration on the lamp ends is a poor electrical connection at the lamp. You may notice discoloration on the anode/cathode lead insulation.

Posted by Cary Neumann (Member # 1665) on 06-17-2003, 12:23 AM:

We are using; Perkin Elmer: XM 2000H/VC/G and LTI: LTIX 2000W-H XENON short arc lamps.
in Lamphouse Strong Lume-x; Model: 65001-1
I will check all your suggestions to check if we can see what's going on.
Everything appears to be working properly, and we always allow 20 minutes to cool down before shut down.
Thanks to all for your suggestions [Smile]

talk to you later, Cary

Posted by Dave Macaulay (Member # 813) on 06-17-2003, 10:16 PM:

The blower in the SLX is prone to clogging. If the rotor vanes are coated with grease and dust (the normal situation) take the blower right out and disassemble it, remove the rotor and then the motor. I usually use gunk and then hot soapy water plus a lot of scrubbing to get the rotor and housing clean. Oil the motor's bearings (don't wash the motor!) while you have it out out and the oil holes are accessible.
You need an exhaust fan, not just the internal blower. The internal fan should freewheel (without power) on the suction from your exhaust fan.
The quartz glass envelope of the lamp is happy at ridiculous temperatures, but the seal - the area where the glass attaches to the metal electrodes - must be kept relatively cool. Overheating the seal area can cause either a leak (which is boring but still kills the lamp) or an explosion. The problem is the difference in thermal expansion rates between quartz and metal. The seal is made of a special glass that has an expansion rate that's supposed to compensate but it only compensates up to a certain temperature, at which point something gives.
The cathode seal is usually not a problem, it's right in the airflow through the mirror hole and not in the light beam. The anode seal is not directly air-cooled and it's right out there in the centre of the light beam. If the alignment is correct it should be in a cone of low intensity light though. Misaligning the lamp can focus a LOT of heat on the anode end of the lamp. If the whole lamphouse is misaligned to the projector, the odd lamp alignment required to get decent light on the screen can do the same thing.
If you use heat filters make sure the glass is at a slight angle, the heat gets sent straight back to the lamp otherwise.

Most likely problems: either the cooling is insufficient or you are overdriving the lamp. Check the accuracy of the ammeter.

The rectifier you have is sensitive to input voltage fluctuations. Possibly your line voltage goes up occasionally and thus increases the current too much? This is fairly common where a major power user is nearby - industrial areas or entertainment districts, also in rural locations where a single power feed covers a large area. I've run into this where setting the lamp current during the day when a nearby industry is running led to very high operating current at night when the factory is shut down.

Posted by Jack Ondracek (Member # 1466) on 06-18-2003, 12:43 AM:

I got an email from one of my suppliers last night. He specifically mentioned Perkin Elmer bulbs, saying that they were getting their bulbs made in China and "they're popping like popcorn".

Posted by Gordon McLeod (Member # 33) on 06-21-2003, 03:54 PM:

I was told the PE has sold the xenon lamp division to a chineese business concern

Posted by Aaron Mehocic (Member # 15) on 06-21-2003, 10:09 PM:

Mark Gulbrandsen has mentioned this in a few of his posts in other threads. Once again quality goes down the shit shoot due to corporate sell outs and "realignments". ORC made a good lamp, but since Perkin-Elmer took over, there have been noticible shortcomings in their product to say the least.

The Soviets sold a lamp that would often explode prematurely. I wonder if this is the ChiCom's version. [Eek!]

Lets hope not.

Posted by Gracia L. Babbidge (Member # 582) on 06-23-2003, 11:56 AM:

One theatre I was at once purchased a few xenon lamps from a newer company that had 'Hollywood' in their name. And I'd advise against getting xenons from them.
We had one of the Hollywood lamps running on screen 9, and an Osram lamp on screen 8, and not only did the Osram put about twice as much light on-screen, it long out-lived the Hollywood piece of [bs]

- which blew up in the lamphouse somewhere between 800 and 1000 hours, whereas the Osram was at 5000+ hours when it got swapped out.
I know, I know, it should have been changed sooner, but things didn't work out that way... [Roll Eyes]

Posted by Scott Norwood (Member # 30) on 09-05-2003, 07:03 AM:

I just had my first bulb explosion last night. It was more of a "crash" (like a big plate glass window breaking) than a "boom." This was one of our kick-ass (not) LTI 2000 W/H bulbs--running at 75 amps and with a whopping (not) 1200 or so hours--in a Strong Highlight II lamphouse, and it happened mid-show. I was maybe twenty feet away (working at the rewind bench) when it happened.

The explosion was violent enough to crack the green window in the shutter guard (Simplex X-L PR1014 projector). It also caused visible damage to the (metal) reflector and left bits of quartz all of the lamphouse and shutter guard area of the projector.

The weird thing is that the positive (anode?) end of the dead lamp almost looked burned--not melted. Not sure if this happened as a result of the explosion or if it caused it. There wasn't any visible damage or charring to other parts of the bulb, and all connections appeared to be tight.

Obviously, we'll be sending the bulb (what's left of it, anyway) back to LTI to see what they say, but my current thinking is that this was a defective bulb. The lamphouse/rectifier is fairly new (five years old) and we were getting 4000+ hours with Osram bulbs and 2500 or so hours with LTI bulbs. I suppose that the ammeter might be defective, but that seems unlikely given the lifetimes that we were seeing with other bulbs and given that we have never run 2k bulbs at more than 80 amps.

We lost the rest of that show (platter house with one machine per screen), but the second show (with new LTI bulb) ran fine, and the damaged reflector didn't seem to affect image quality.

As a side note: are there any automation systems which use a photocell (or other device) inside the lamphouse and will kill the show if there is no light? If there hadn't been someone in the booth when this happened, the audience could easily have been left sitting in the dark until someone complained to an usher.

Posted by Dave Macaulay (Member # 813) on 09-05-2003, 07:22 AM:

The "burned" anode definitely points to a problem. There's no heat made after the explosion so either the heating caused the failure, or possibly the anode managed to short to ground after the explosion but that would show some arcing damage to the metal.

Automation-wise, I'm only familiar with the Strong CNA automation that has a lamp fail shutoff. They attach a magnetic sensor - identical to their newer door switch sensor that uses the little magnet on the door - to a lamp DC cable. This switches in the magnetic field from the lamp current in the wire. Undoubtedly some other automations have a similar feature.

Posted by Michael Gonzalez (Member # 593) on 09-05-2003, 11:33 AM:

Slightly off topic but I just received in 3 Xennon bulbs and one of them exploded inside the box in shipping. The interesting thing is that there is glass falling out of the sides of the unopened box (the bulb box not the shipping box)even though the bulbs are suppose to be in a plastic case to prevent this from happening. Even though I am really curious about it, I am smart enough to leave the box unopened so that they will KNOW that we got it in that condition.

Posted by Jeff Klump (Member # 1870) on 09-05-2003, 04:40 PM:

We must be lucky to be receiving Christie and Osram bulbs because none of ours have ever been dead on delivery. 3 of our 16 lamphouses have damages from explosions after only about 800 hrs. One of which blew after only 250. All three were 4000w ORC bulbs. Ever since I've been a Osram/Christie fan.

Posted by John Pytlak (Member # 331) on 09-06-2003, 06:09 AM:

quote:
The weird thing is that the positive (anode?) end of the dead lamp almost looked burned--not melted. Not sure if this happened as a result of the explosion or if it caused it. There wasn't any visible damage or charring to other parts of the bulb, and all connections appeared to be tight.

If the connection look "burned" or discolored, it's likely that a poor connection caused some localized heating, leading to the failure of the lamp.

Posted by Chris Hipp (Member # 1788) on 09-06-2003, 03:05 PM:

Have you guys ever seen the way the Fed ex guys handle the Xenon bulbs? I don't think they have any idea what they are.

As far as Osram, Usually Osram bulbs are great for a very long time, but lately I've been having problems with them. Two bulb explosions at low hours and a seal failure all in the past 6 months.

Some other theatres nearby have been having the same problems with them.

However, I still prefer Osram.

Posted by John Walsh (Member # 168) on 09-06-2003, 03:53 PM:

The old Cinemation had photocells to detect if the lamp was on.

Posted by Travis Hubrig (Member # 1745) on 09-06-2003, 08:46 PM:

Scott, It seems that you are getting your money's worth out of your bulbs... What is the warranty life of those bulbs? One major mistake that I have made in the past is not tightening the bulbs good enough. After the intial installation the bulb should be checked again for tightness within the first few days. Burnt or discolored ends on the bulb is an indicator that maybe there is a loose connection... I went through three bulbs until I discovered that I had a bad positive DC cable to my bulb.

Posted by Paul G. Thompson (Member # 655) on 09-07-2003, 02:01 PM:

Are you overdriving the lamps?

Posted by Leo Enticknap (Member # 534) on 09-08-2003, 01:49 AM:

quote:
The Soviets sold a lamp that would often explode prematurely.

So that's how they're getting rid of all those unused SS-20s... [Big Grin]

Posted by Ben Stephenson (Member # 741) on 09-17-2003, 08:01 PM:

Osram have just asked for all there 5K Xenons back in the UK, They are very quick to explode after very few hours.

Just have a batch of 4K Osram Xenons that fail to strike,

Good Job ......

Posted by Dennis M Dow Jr (Member # 1970) on 10-25-2003, 08:59 PM:

We have been very lucky with our osrams... only one explosion (new bulb first showing) in 5 yrs of operation....

Posted by Jean-Michel Grin (Member # 1360) on 10-25-2003, 09:11 PM:

One day, a customer asked to the aprentice projectionist: Your picture is verry dark, do something !
An then the projectionist raised up the currrent at the rectifier...
And of course the xenon lamp exploded [Eek!]

Posted by Michael Schaffer (Member # 1204) on 10-25-2003, 10:03 PM:

That leads me to a different but related questions: which face shield/mask really protects you from a xenon explosion? I never had a lamp blow up on me outside the projector, and I would tend to think that a sturdy plastic shield should be enough to protect you from a cold explosion, but...

Posted by Randy Stankey (Member # 64) on 10-25-2003, 10:38 PM:

I have done a few science experiments in this department.

I have dropped them from a second story balcony onto concrete. I have chucked them into dumpsters. I have shot them with a .22 cal. rifle.

They shatter pretty nicely. They give a good loud, "POP!" sound when they break. Chunks of glass up to a couple-three inches in diameter will fly as far as 10 to 20 feet. Shards of glass ranging from a milimeter to several centimeters in size fly in all directions. Anything within 10 feet of the exploding lamp will definately suffer damage. I'd estimate the "kill zone" to be a good 20 to 25 feet in diameter. Glass particles can also ricochet off objects.

If exploded inside the thin cardboard boxes like the Osrams come in (without the "clam shell" in place) some of the larger pieces may penetrate the box. If exploded in the same manner in a heavier box like the Christies come in pieces of glass may pierce the inner layer of the corrigated cardboard but none will penetrate.

Obviously, a heavy leather welders apron and gloves should be worn when working with xenon lamps but I would also advise a good pair of safety goggles be worn underneath the face shield. No glass particles will penetrate the Lexan® face shield but, because of the possibility of ricocheting glass, some of the particles may get under the bottom of the shield and into your face.

Hey, if you get a cut on your face from a riccochet it's no big deal. Cuts heal. You might end up with a scar on your face but when people ask you where you got the scar you can impress them by saying, "Oh, I got it in an explosion..." [Wink]

Not so with your eyes! A projectionist who can't see can't keep the picture in focus, can he? To be injured for life and permanently out of work is a really bad thing!

Just wear the goggles, dammitt!

I would say that goggles and gloves are manditory but you can save some money on the rest of the gear if you have a big, thick, heavy coat. Something like a Carhartt® coat should be sufficient. If you have an old, retired hunting jacket you could hang it up on a hook somewhere in your booth. Not only could you use it for lamp changing duty, you have something on hand to wear if you need to go outside in cold weather.

The goggles, shield and gloves are still mandatory!

Posted by Gordon McLeod (Member # 33) on 10-26-2003, 09:21 AM:

Often the anode in particular will oxidise after an explosion as it is red hot and look burnt

Posted by John Pytlak (Member # 331) on 10-27-2003, 11:30 AM:

Randy's suggestion of using "double protection" of both safety goggles and a full face shield is a good one. Your eyes are irreplaceable, and the flying quartz shards from an exploding lamp are unpredictable, and could get around just a face shield. Protect your hands and wrists too, as well as your torso and neck. [Eek!]

Posted by Timothy Eiler (Member # 383) on 10-27-2003, 12:34 PM:

I have seen a couple cases over the years where after an explosion The reflector directs light right back on the the bulb itself and causes overheating and premature failure.

Posted by John Pytlak (Member # 331) on 10-27-2003, 12:42 PM:

quote:
I have seen a couple cases over the years where after an explosion The reflector directs light right back on the the bulb itself and causes overheating and premature failure

Are you sure the explosion caused the reflector to change? I suspect if the heat is being reflected back onto the lamp, the problem was there all along. The IR heat energy removed by the heat filter(s) does have to go somewhere. Be sure that a metal mirror with a dichroic coating is well cooled by sufficient airflow, and that any additional heat filters reflect the infrared energy to a well-cooled heat sink, and not back into the optical system.

Posted by Gordon McLeod (Member # 33) on 10-27-2003, 01:06 PM:

In the older verticle lamphouses that had 2 reflectors it was possible to focus back on the lamp
The rear reflector is an ellipitacl one so its second focus is past the apperture plate but the front one was spherical and it reflected back on the lamp all the energy that was projecting forward directly from the lamp and being wasted on the interior of the lamphouse
The arc image was also inverted so it tended to smooth out the light field extensively
It was important to focus the secondary inverted image to be just inside the arc gap to prevent the reflected image burning the electrod or a hole in the quartz

Posted by Timothy Eiler (Member # 383) on 10-27-2003, 01:43 PM:

quote:
Are you sure the explosion caused the reflector to change?

As the reflector look perfect before the explosion and there several big dings in it afterwards I would say yes.
Running the xetron Lamp with 2k bulbs for 3,000 to 3,200 (per company policy) for 7 years With no problems. Then one explodes. The next 3 bulbs only get 700-800 hours with visable overheating. New Reflector is install and there are no more problems

Posted by John Pytlak (Member # 331) on 10-27-2003, 02:48 PM:

quote:
Running the xetron Lamp with 2k bulbs for 3,000 to 3,200 (per company policy) for 7 years With no problems. Then one explodes. The next 3 bulbs only get 700-800 hours with visable overheating. New Reflector is install and there are no more problems

Wow! Seems like a chance in a million that those "dings" would reshape the reflector to re-reflect the energy back to the lamp. Any chance the explosion did something else, like change the lamp mounts such that there was some physical stress being put on the lamp?