Super Trouper 1600w Lamp Shelf Life

[moveasidered]

Hello again,
We have a lot (around 8) spare Xenon 1600w lamps for our three Super Trouper followspots.
The oldest of these lamps were made in 1999, with the newest being from around 2002 or 2003 i think.
I have heard that they only have a shelf life of a few years- is that correct? Most of the advice i am getting is to put in the lamp and give it a try, but i was looking for something a little more like an actual guideline.
There are several different brands of bulb in there, one being Osram.
Any suggestions?
Thanks!

 

[FatherMurphy]

The general guideline I have been told by Strong is that the shelf life should be considered to be ten years. After that, the chances are getting greater that the lamp will have outgassed enough to lower the internal pressure sufficient to cause problems striking, or that surface stresses may make the lamp more prone to exploding during use, which usually damages the reflector along with scaring the operator.

Having said that, I do know of some 20+ year old lamps still in regular (annual) service without strike problems, and only one in-service failure.

It's a question for your budget - do you replace an $800 lamp that's never been used, or take the chance on later replacing a $2000 reflector?

Strong is currently supplying Philips lamps, iirc, Osram is a good name, anything marked 'Hanovia' is automatically old, they haven't made spot lamps for years.

 

[PeteEngel]

The shelf live question in regards to arc source lamps is an important issue. As a rule of thumb, I use 4 to 7 years as a guide (for HMI). The biggest failure area will be the ceramic (?) sealer where the quartz and the metal contacts meet at either end of the lamp. In a double ended, single envelope lamp this could mean the integrity (and pressure) of the envelope is no longer to specification and the lamp should not strike (???). I am not sure if this would cause an overpressure inside the lamp during the ignition process and a potential critical failure or not, and since when Xenon lamps blow they tend to damage the expensive reflector that surrounds the lamp, the "just try them" testing method may cause more harm than good. Mark D would have more info on this process though.

 

[DELO72]

The shelf live question in regards to arc source lamps is an important issue. As a rule of thumb, I use 4 to 7 years as a guide (for HMI). The biggest failure area will be the ceramic (?) sealer where the quartz and the metal contacts meet at either end of the lamp. In a double ended, single envelope lamp this could mean the integrity (and pressure) of the envelope is no longer to specification and the lamp should not strike (???). I am not sure if this would cause an overpressure inside the lamp during the ignition process and a potential critical failure or not, and since when Xenon lamps blow they tend to damage the expensive reflector that surrounds the lamp, the "just try them" testing method may cause more harm than good. Mark D would have more info on this process though.

Hi Folks,

I'll have to check with the factory and find out. Xenon isn't my product line, so my technical knowledge on it is minimal- but I'm happy to find out for you.

Pete is correct in that for lamps with potting cement (the "ceramic sealer" that fixes the quartz capusle into the base), that the cement can break down over time. A lot of it is based on the environment they are stored in. High humidity vs. very dry. I saw one instance of an unopened box of new HPLs from 1998, that a customer showed me where the lamp capsules wobbled in the heatsink because the potting cement had dried up and crumbled into dust on the shelf during that time.

NOW-- that said, XBO Xenon lamps (at least OSRAM ones- I don't know enough about the product line and our competitors' lamp design to speak to it) don't use potting cement. They use a high temperature teflon compression seal to fix the lamp burner into the end caps, so the "potting cement" issue doesn't factor into this particular scenario. I'll try to find out about the life/risk though and post what I learn.

Cheers,

Mark

 

[JD]

I know I had a 575 HMI from 1979 that I fired up last year. Worked fine. Same with PAR lamps, had a six pack from about the same time hiding in an attic eve and put them into service no problems. Still have some mercury rectifiers from antique battery chargers (1920?) that work. I don't think there is a specific problem with sealed glass.

That being said, xenon lamps are a bit different. They contain a pressure, and have a very complicated / layered seal. I would suspect if there had been an age related failure, it would be a lack-of-strike issue. Could there be a stress related failure due to age? Not aware of glass or quartz changing that much due to time, BUT, xenon lamps are like hand grenades right out of the box new, so anything goes!

You have 8 of them..... That's about $6,400 in lamps. Seams an incredible waste to throw them out.

 

[DELO72]

Hello again,
We have a lot (around 8) spare Xenon 1600w lamps for our three Super Trouper followspots.
The oldest of these lamps were made in 1999, with the newest being from around 2002 or 2003 i think.
I have heard that they only have a shelf life of a few years- is that correct? Most of the advice i am getting is to put in the lamp and give it a try, but i was looking for something a little more like an actual guideline.
There are several different brands of bulb in there, one being Osram.
Any suggestions?
Thanks!

So... the word from the factory is that while they do not know of any specific root cause that would lead to definitive failure due to time, we have absolutely no actual testing to support a claim one way or the other (we haven't kept lamps around for 10 years and then tested them), so we don't know. This would fall under the "Use at own risk" category. We make the lamps and ship them, so rarely see what happens years down the road under control group settings. (Ie. Have they been properly cared for, has the ignitor and ballast in the fixture been tested and maintained, etc.?)

Sorry to not be of better help on this one.

 

[FatherMurphy]

If I'm remembering my Strong training correctly, the lamps are pressurized at 150 psi when cold, increasing to around 300 psi at full operating temperature. Outgassing for any reason lowers the internal cold pressure, and fail-to-strike problems start happening. This can happen regardless of use or non-use, although the thermal cycling of use seems to speed the process.

The explosion issue is more debateable. Arguably, the stress of sitting in a box on a shelf is probably less than the thermal stresses of being heated and cooled in use, or of bouncing down the road in a truck, then again older lamps have been retaining their pressure for years, and a form of cyclic fatigue failure could possibly result, or at least start the lamp from a weaker point than a brand new one as the thermal cycles of being used begin.

As DELO72 points out, there hasn't been a lot of scientific testing on the matter, but Strong does know when people call in for replacement reflectors to repair lamp explosions, and they're of the opinion that old lamps can be a contributing factor. Jack Schimdt of Strong used to make something of a hobby of tracking down the root causes of odd failure modes, so I'd give a bit of weight to their thoughts on the matter. Then again, as my boss once pointed out, they're in the business of selling replacement lamps.

I'd be inclined to at least try them, but be ready to replace them at the first hint of trouble, including taking more than three or four pings to strike.

 

[DuckJordan]

My gut feeling is to sell them at a lower cost than new and only keep three spares in stock. The lamps in super troopers don't die to often and if you have a replacement lamp for each then why keep such an expensive lamp in stock. I work in a road house and the two years I've been here (with the troupers we have getting fairly regular usage) I've only seen one lamp die. It was catastrophic so no big explosions just un-struck and wouldn't re-strike.

 

[techieman33]

That is a total waste of money, it makes no sense to keep that many spare lamps on hand. I could maybe understand having 3 on hand but that's the most I could see. Our troopers see very little use, they get fired up about 15 times a year for maybe 50 hours total. We prefer to use our lycian midget 1209 hp's since the angle to the stage is much better and they are brighter since they have a much shorter throw. Anyway what we do when we replace trooper lamps (we always replace both of them) is keep the old ones as the spares. And should there be a failure we would replace with the old lamp, and then order new.

 

[JD]

The following is just my gut feeling as there has been no study on the subject. If they were mine, I would use them. Could they blow? Yes. Simply no data to say they would or would not. Again, with no information that backs my following statement up, I suspect they could be in a box for 100 years and still work, provided the seals were good.

One of the reasons I say this is my experience with antique vacuum tubes. Some of which are now nearing 100 years of age. For the most part, unless the seals were bad at manufacturer, I've never tried one that didn't work. Of course with tubes, they have a silver flash and getter that will turn to white powder if there is a leak, so you have a pretty good idea just from observing what it looks like.

Here's a nice video of a guy firing up a 100 year old 6 phase (you read that right) mercury arc rectifier tube. (about 100 pounds of glass!)

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[FMEng]

A lot of very old vacuum tubes do maintain their seal and work fine. I have boxes full that are 50+ years old that work like new. But, a few do go "gassy" from a bad seal. It is a fairly common failure mode, along with low cathode emission. So, I'm not sure the analogy is the best one.

I would look at it this way: Keep the money saved from not buying new spares and use it to self-insure for a replacement reflector if needed. If the lamps are worth $6,400 it is worth gambling on a damaged reflector, unless you just cannot risk the downtime to get one.

 

[DELO72]

That is a total waste of money, it makes no sense to keep that many spare lamps on hand..

What? I could not disagree more, and this isn't just the Light Bulb manufacturer part of me talking. [Read: yes it is.] You never know when a zombie apocalypse is going to happen and you find yourself trying to light Act 2 of The Music Man and you have no special for Mayor Shin in Shipoopi! You should always have at LEAST 20 spares of every lamp on hand--you know... just in case.



*smirk*

 

[derekleffew]

... Act 2 of The Music Man and you have no special for Mayor Shin in Shipoopi! ...

Marcellus sings Shipoopi; I don't recall Mayor Shin even being in that number.

I also don't remember it being during a football game, but I must be wrong on that one.

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