Film-Tech Forum ARCHIVE: What is the average life of a xenon bulb?

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Posted by Robert D. LaValley (Member # 1867) on 09-28-2003, 04:38 PM:

Seriously what is the average life of a xenon bulb?

I've gotten surprisingly alot of different answers to this question.. It all depends on the wattage of the bulb, the kind of bulb (oshram .. etc..), whether you rotate the bulb or not, whether your rectifier feels like pushing A/C or D/C today... Those are just some of the things that have been said.. I remember back when I was with regal we changed our bulbs pretty regularly and didn't rotate them.. How long should you run a bulb and should you or shouldn't you rotate them?

Posted by Adam Martin (Member # 641) on 09-28-2003, 05:07 PM:

All of the different answers you were given were all correct.

Posted by Michael Schaffer (Member # 1204) on 09-28-2003, 05:16 PM:

You only need to rotate the lamp after 1/2 of its warranted life span if the upper side of the bulb has darkened a bit.

Posted by Robert D. LaValley (Member # 1867) on 09-28-2003, 05:28 PM:

But does the rotation help?? I've heard it really doesn't add that much to the life span to be worth the hassel...

Posted by Gordon McLeod (Member # 33) on 09-28-2003, 05:45 PM:

It makes a big difference in the long term
Do a search and read the many times this subject has come up

Posted by Paul G. Thompson (Member # 655) on 09-29-2003, 01:08 AM:

There are so many factors involved. Lot of it depends on the manufacturer, lamphouse, power supply, ventilation, current, voltage, wattage of the bulb, how many ignitions and how good a shape the power supply is in.

The only time I rotate my bulbs is when they start to darken on the envelope. I can easily get anywhere from 2500 to 4500 hours on a Christie 2500 watt bulb used in a Strong Super Lumex.

In my opinion, Christie is the way to go. At one time the Osram was....but the last ones I used just didn't seem to give me the mileage like a Christie.

Posted by Michael Harlow (Member # 1353) on 09-29-2003, 05:06 AM:

Dont talk to me about xenon lamps [Confused]

Posted by Thomas Hauerslev (Member # 566) on 09-29-2003, 07:21 AM:

In the 1980s at ABCinema+D and Cinema 1-8 here in Copenhagen, I remember OSRAMs 1600 w were running more than 6000 hours. And the light was still good. True workhorses.

Posted by Paul G. Thompson (Member # 655) on 09-29-2003, 12:33 PM:

Thomas, that was the '80's. That was the time I was implying Osram was the best. In those days, I used nothing but Osram.

However, this is 2003.

Posted by Jeff Taylor (Member # 443) on 09-29-2003, 01:30 PM:

In the first place, "life" is a relative term when it comes to xenons, unless you measure it by a cataclysmic explosion at the end. Personally, I have NEVER replaced one that was totally dead...it's always been a question of how patient I could be in terms of hard striking when they pile up hours. In the end, I ususally change them long before they will absolutely refuse to strike.

Posted by German Marin (Member # 918) on 09-29-2003, 01:41 PM:

I say Xenon lamp's life is like our own life: If I smoke a lot, drink alcohol, don't sleep enough, etc. all these things make your life short

Posted by Jack Ondracek (Member # 1466) on 09-29-2003, 01:54 PM:

This is kicking an injured dog... but I still don't quite understand the value gained by rotating these bulbs... at least as it balances against the increased risk of problems.

A 7,000 watt bulb shows almost no discoloration at half-life, and not much more than that by the time you're 10% past warranty. By rights, it probably should be replaced, or at best, rotated to "emergency spare" status. 550 hours isn't a lot, but it gets us most of the way through a Summer drive-in season.

I get much the same from the 4kW bulbs I use. 1,500+ hours are common before they start looking like rotating might be a good idea. These things are out of pro-rated warranty by 1,200 hours, so I'm on my own when I keep them in the lamphouse... and I'm a whole lot more interested in keeping my glass X-60 reflector than trying to bleed a bulb until it won't light.

Same argument goes for smaller bulbs... 1,500 hours & you're on your own.

Over and above all that, I have yet to rotate an otherwise perfectly fine bulb and NOT have it go unstable on me. Trying to wait it out... or jacking up the juice for a while has had inconsistent results.

I know this is another of those personal preference issues... but I seem to get the best life out of my bulbs by leaving them the heck alone, other than opening up the housings occasionally for cleaning.

Aside from that: Having grown up with carbons, buying xenon bulbs has always been a "cost of business" issue for me. You can't "bleed" a carbon. When you're out, you've got no light until you buy another case. Considering the declining output of a xenon bulb, shooting for hour records just results in declining image quality for the sake of putting off what should be a planned cost of running the booth.

Posted by Brad Miller (Member # 2) on 09-29-2003, 03:52 PM:

For what it's worth, I have never had the need to rotate a bulb in a Christie SLC lamphouse and I get ridiculous lifespan out of bulbs used in those units. In all other lamphouses I have used (including older model Christies), the lifespan was never as good and some of them necessitated rotating the bulb due to darkening or arc wandering...but oddly enough not on every bulb.

The only exception to that is I never had the need to rotate a bulb in a vertically mounted lamphouse design. The problem was a matter of getting good light out of them.

Posted by Robert D. LaValley (Member # 1867) on 09-29-2003, 06:49 PM:

Hard strike? I run christie lamp house, kni-tron single phase recitifier, and the lamp is a 1k lamp oshram.. Brand new installed in july of 2003. Right now I have slight darking on the underside of the lamp, and I am getting a stobe effect very rarely but it does happen. More often I loose amperage, the lamp strikes a million times, or it just flashes like someone flipping a switch to a regular light bulb.

So these problems prompted me to ask the life span question. Since I did do bulb changes at regal pretty regularly I only came across a bad lamp once out of five years.. Could this be my second bad lamp?

I also have checked all the conections to make sure everything was tight. I don't know if the ventilation is that great either becuase both of my lamp houses do get awfully hot.

Posted by Mark Gulbrandsen (Member # 72) on 09-29-2003, 09:38 PM:

From a point of liability you guys all missed it. The life rating of a Xenon lamp is the manufacturers rated hours plus about 15% maximum. Past that you run it at your own risk. Many do [Roll Eyes]

.
Mark @ CLACO

Posted by Gordon McLeod (Member # 33) on 09-29-2003, 10:24 PM:

The reason you get multiple striking is the no load voltage of many Kniesly PS's is too low for a lamp with a few hours on it
THe ignitor will try to fire until the knowload voltage drops to the operating level
kniesley make boost supply booster kits for there rectifiers to help

Posted by Jack Ondracek (Member # 1466) on 09-29-2003, 11:00 PM:

quote:
From a point of liability you guys all missed it. The life rating of a Xenon lamp is the manufacturers rated hours plus about 15% maximum. Past that you run it at your own risk

...thought that's what I said... [eyes]

Posted by Paul G. Thompson (Member # 655) on 09-29-2003, 11:28 PM:

Brad said:

quote:
For what it's worth, I have never had the need to rotate a bulb in a Christie SLC lamphouse and I get ridiculous lifespan out of bulbs used in those units.

I have experienced the same thing. Getting 6,000 hours out of a Christie bulb (even the 4000 watt lamp) in the Christie SLC seems to be a normal occurrence.

Jack said:

quote:
Over and above all that, I have yet to rotate an otherwise perfectly fine bulb and NOT have it go unstable on me. Trying to wait it out... or jacking up the juice for a while has had inconsistent results.

That's about the same way I look at it. [Smile]

Posted by John Pytlak (Member # 331) on 09-29-2003, 11:38 PM:

As others have noted, risk of catastrophic explosion increases as lamps are run well beyond their warranteed life -- lost shows and damaged lamphouse components cost alot more than replacing a lamp before it becomes "iffy".

Likewise, unreliable ignition, flickering light output, and dim screens compromise presentation quality.

Posted by Jack Ondracek (Member # 1466) on 09-30-2003, 12:24 AM:

I'm wondering what it is about the SLC that works so well with the bulbs... above-average filtering?... better cooling?... lack of reflections back to the bulb?... all the above? I do know for a fact that you can't get anywhere near 6000 good hours out of a 4kW bulb in an X-60 or Ultra 80, even with a switcher.

Maybe you guys are just leaving these things on 24/7, eh????? [Cool]

Posted by Dustin Mitchell (Member # 372) on 09-30-2003, 12:37 AM:

In the six years that I have worked at this theatre we have had one bulb explode. It was still under warranty.

Bulbs should be changed when the envelope begins to show signs of age and/or the light it puts out is no longer at your presentation standards. I have run bulbs in Christie SLC lamphouses and Strong Super Lume-x's up to and over 4,000 with no visible signs of aging in the envelope and still putting 16fl on the screen (as measured by a light meter).

I understand that in the early days of xenon bulb usage they tended to 'catastrophicaly fail' much more often than they do today. Things have changed apparantly (I wouldn't know since I haven't been in this business that long). Automaticaly changing bulbs at 125% of warranty is usually a waste of money, period.

Posted by Michael Schaffer (Member # 1204) on 09-30-2003, 01:40 AM:

quote:
Right now I have slight darking on the underside of the lamp

Misaligned stabilizing magnet?

Posted by Manny Knowles (Member # 1171) on 10-01-2003, 12:45 PM:

Our projectors use 2kW or 1600W lamps and we run an average of three and a half shows a day. The lamps strike anew for each showing (not on all day). For lamp wear calculations, I use 2 hours as some movies are longer and some are shorter.

In one day, (3.5 showings x 2 hours) + 3.5 strikes = 10.5 hours. In 30 days that's 315 hours and in 6 months we're at 1890 hours, so I try to change all of the lamps in April (in time for summer releases) and October (just before Thanksgiving/Christmas).

Oh my! I guess this means I'm due!

We've had some premature bulb deaths but we have been using PerkinElmer lamps and quite a few Film-Techers have no faith in PE for this reason. I'm going to switch to Christie or Ushio for this next set of changes.

Aren't Christie and Ushio "one and the same" ?

[ 10-01-2003, 08:38 PM: Message edited by: Manny Knowles ]

Posted by Scott Norwood (Member # 30) on 10-01-2003, 06:02 PM:

The lamphouse (or at least the cooling provided by the lamphouse) seems to make a big difference in lamp life. I've gotten 4000 hours out of several 2kw Osram bulbs in Strong Highlight IIs; the same bulbs would barely go for 2000 hours before starting to flicker in Christie H20s.

At most theatres, bulbs usually get changed when they start to flicker or when they're obviously old (3500-4000 hours for 2kw; less for larger bulbs). Changeover houses should replace both bulbs at the same time. I've personally seen one explosion (presumably a defective bulb) and have heard about one depressurization (bulb was 15 years old with a few hundred hours; there was no noise, but the screen went dark and the bulb wouldn't re-strike). I also know of one lamphouse where 3kw bulbs only seem to last about 600 hours before either flickering badly or turning almost completely black.

For the most part, though, bulbs just start to flicker and get dimmer as they age.

Related question: how many spare bulbs do you keep on hand? Obviously, every theatre should have at least one new spare of every type of bulb that is in use, but how important is it to keep more than one?

Posted by Steve Kraus (Member # 476) on 10-01-2003, 07:54 PM:

A small theatre on a tight budget can probably get by with keeping a few old bulbs that were removed in good working order as spares rather than tying up a lot of cash on the shelf. But obviously at least one new spare is preferred.

Posted by Jack Ondracek (Member # 1466) on 10-01-2003, 08:24 PM:

I have one 7kW system... I keep one new lamp and one used spare.
I have 3 4kW systems, two in one location and one in the other. There's one new spare at that place, plus one used. At the location with two, the usage is very even, so I keep two new bulbs and two used spares.
Of the 3 2kW systems I have in one location, I keep two new lamps & two used spares. I don't really know why I keep the used bulbs... guess if all hell broke loose, I'd have replacements onhand for everything.

Lamp replacements occur between 6 & 12 months, so we don't really keep a lot of long-term stock onhand.

The 4 & 7kW lamps will eventually be running in the same model lamphouse. Once that's done, I'll keep a replacement reflector in stock (it's a glass dichroic). The smaller lamps are all metal Super Lume-X, so it doesn't seem to me that keeping a spare in the booth is that critical.

Posted by Manny Knowles (Member # 1171) on 10-01-2003, 08:36 PM:

If a lamp looks good when I remove it I will keep it as an emergency spare. I have several like that by now and I rarely have to use them.

I keep about 2 of each type on hand brand-new. Those are the real spares. As I mentioned, sometimes they have failed prematurely -- even right out of the box. This is where having a few "good used" spares comes in handy.

Having said that, I would not advise keeping the used ones as the main spares. I know of a theatre that did this -- and may still be doing it. Basically, if a lamp died or started acting up they would change it out with one of the used ones and wait for a new bulb to arrive. The reason I don't like this approach is that it means someone has to change a lamp twice. Not only is this double work, it also doubles the risk for possible injury during the change-out.

Posted by Aaron Sisemore (Member # 145) on 10-01-2003, 11:27 PM:

quote:
Aren't Christie and Ushio "one and the same" ?

Yes, except for the name engraved into the ends of the bulbs. Ushio is the parent company of Christie.

There is another bulb that looks very similar to a Christie/Ushio bulb, these are the 'Yumex' brand bulbs (designed by former Ushio engineers, thus the similarity) . I have tried a few in the past, and they were OK... Better than ORC/PerkinElmer and Chinese bulbs, but not as good as 'real' Christies or Osrams.

-Aaron