# whats the life of a stored bulb?



## benchmade_boy (Dec 2, 2006)

:thinking:hi all i am curius if i buy a couple of p60 bulbs right now just incase i need them how long will the shelf life be i mean will it still have the same perfomance in ten years as it would in a week?

Thanks, David


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## Illum (Dec 2, 2006)

I doubt theres a shelf life of bulbs, since they dont chemically react without power input, only thing I would worry is the spring and contact oxidation, but i doubt you will store that bulb in excess of 10 years...unless you forgot about it in a cigar box somewhere in the attic

say, thats a good idea, with the current inflation their not going to get any cheaper:goodjob:


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## benchmade_boy (Dec 2, 2006)

Illum_the_nation said:


> but i doubt you will store that bulb in excess of 10 years...unless you forgot about it in a cigar box somewhere in the attic
> 
> say, thats a good idea, with the current inflation their not going to get any cheaper:goodjob:


 yeah i knew i most likley wouldnt have them for ten years but 1 or 2 is a real possibility and i just wanted to make sure that if i did i wasnt wasting 20 bucks a pop just for them to go bad after 2 or 3 years.

and yes this is probably going to be the cheapist we see them cuz i remember a year and a half ago i was complaing cuz i bought 12 cr123 to go with my g2 and they were like $14.99 or somthing like that and know they are $25.99.


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## Illum (Dec 3, 2006)

benchmade_boy said:


> yeah i knew i most likley wouldnt have them for ten years but 1 or 2 is a real possibility and i just wanted to make sure that if i did i wasnt wasting 20 bucks a pop just for them to go bad after 2 or 3 years.
> 
> and yes this is probably going to be the cheapist we see them cuz i remember a year and a half ago i was complaing cuz i bought 12 cr123 to go with my g2 and they were like $14.99 or somthing like that and know they are $25.99.



I couldnt imagine prices for surefires lights a decade ago...before the inflation
$10 ish for a G2? 

well, $10 was alot back then.....


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## Knight Lights (Dec 3, 2006)

I came across some lamps that were more than 40 years old recently, They were for a 6 volt lantern light, and with our dry desert air in Eastern Washington they were looked new, (well, the lamps did, the boxes were basically only slightly more than dust!). 

They fired right up and looked great on 7.2 volts, nothing like a new 1111, but still pretty nice.

I gave them all to nephews, since even Mag lamps look whiter.

Bill


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## benchmade_boy (Dec 3, 2006)

so do you think it would make a differnce if the bulbs have a little runtime on them like 15-30 minuts do you think it would make a differnce after time or would it be the same as a mint bulb?

i wish size15 would chime in im sure he would know


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## leukos (Dec 4, 2006)

Illum_the_nation said:


> I couldnt imagine prices for surefires lights a decade ago...before the inflation
> $10 ish for a G2?
> 
> well, $10 was alot back then.....


 
Actually, the G2 retailed for over $50 when it first came out: http://candlepowerforums.com/vb/showthread.php?t=94&highlight=nitrolon


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## js (Dec 4, 2006)

All the SureFire, Welch Allyn, Carley, Osram, etc. modern lamps should have a practically infinite shelf life. Certainly a good 20 or 30 years. As long as they aren't stored in damp conditions, and aren't physically abused or vibrated or shocked, there is nothing to go bad. And it doesn't matter whether they have any runtime on them or not.

Lamps go bad for three reasons:

1. glass envelope is compromised/broken and fill gas leaks out and oxygen gets in.
2. Tunsgten atoms coat the interior of the glass and darken it to the point where there is significant light loss.
3. The tungsten filament gets thin at one or more points and burns out, and/or gets physically shocked and breaks.

And the contact points outside the bulb could also corrode, but a quick cleaning would restore that, so I didn't include it.

Anyway, as you can see, if the integrity of the glass envelope is good when put into storage, sitting around won't make it bad. It's freakin' glass after all.

And, tungsten atoms are only deposited on the inside of the glass while the filament is HOT, and not at any other time. So that's a non-issue for a storage situation.

And, if the filament is not shocked or knocked, storage will not cause it to break all on its own.

So, as I said, you should be fine if you store your LA's or bare lamps or whatever in a dry, stable/motionless place. Or encased in a shock absorbent material like foam.


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## idleprocess (Dec 4, 2006)

What js said. When not in use, incandescent bulbs are pretty much inert.

I'd guess that the main weak point for a bulb left on a shelf for years is whatever metal is protruding from the glass. It could corrode to near-total uselessness or maybe even to the point that the gas-metal seal is compromised.

A more remote possibility requiring _decades_ is for the glass to "flow" to the point that the envelope ruptures if a thin spot develops. This assumes that the glass used in the envelope is like plate glass which flows slowly downward.

I don't think that the fill gasses could diffuse through the glass over time or gradually get around the glass-metal seals.

If left in a place experiencing signifigant daily temperarture variations, the effects of regular expansion and contraction _might_ compromise the envelope after a _long_ time - probably multiple decades.

I'm just tossing out long-shot possibilities here. I'd think that the shelf-life of the average incandescent lamp would be greater than the average human lifespan.


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## matrixshaman (Dec 4, 2006)

I've got some small flashlight bulbs from 40 years ago at least and they still work! Not something to worry about - they'll likely outlast you


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## tron3 (Dec 4, 2006)

idleprocess said:


> ...
> 
> If left in a place experiencing signifigant daily temperarture variations, the effects of regular expansion and contraction _might_ compromise the envelope after a _long_ time - probably multiple decades.
> ...


 
My front house lights have been experiencing those temp variations for about 38 years. The lights are RARELY turned on, but when last turned on days ago, both lit up.

I am certain these lights have NEVER been replaced. Might be interesting to take them out and see if they become oblonged from hanging upside down all these years.

I have a 1939 flashlight, and as far as I know, it is the original bulb, and it still lights. Glass flow certainly takes MANY decades to become problematic - even with heat. Total mass and weight of the glass may also be a factor.


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## leukos (Dec 4, 2006)

So what is the shelf life of an LED in comparison?


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## Illum (Dec 4, 2006)

leukos said:


> So what is the shelf life of an LED in comparison?



leds can run 100,000 hours continuous...i really doubt the shelf life of the led is less than a couple decades...i mean gee, its under a plastic mold, so its waterproof, chemically stable, non reactive, etc

similarily, theres also the oxidation of contacts if your not storeing them in plastic bags


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## Icebreak (Dec 4, 2006)

Glass flow (I remember my 7th grade chemistry class teaching it) is a myth. Glasses are amorphous solids. That some old windows are thicker on the bottom is because the manufacturing process used didn't produce flat glass. Glaziers installed the panes heavy side down for stability.


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## Illum (Dec 4, 2006)

leukos said:


> Actually, the G2 retailed for over $50 when it first came out: http://candlepowerforums.com/vb/showthread.php?t=94&highlight=nitrolon


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## js (Dec 5, 2006)

Icebreak said:


> Glass flow (I remember my 7th grade chemistry class teaching it) is a myth. Glasses are amorphous solids. That some old windows are thicker on the bottom is because the manufacturing process used didn't produce flat glass. Glaziers installed the panes heavy side down for stability.



This is also my understanding from my Solid State physics class where this subject came up. But, I don't have any definitive answer. A web search might provide one.

In any case, even if glass flow isn't a myth, it wouldn't be a problem over the time spans we are considering.


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## jtr1962 (Dec 5, 2006)

leukos said:


> So what is the shelf life of an LED in comparison?


I'd say the shelf life of both incandescents and LEDs if properly stored is more like _centuries_, perhaps even millennia. There is that bulb in some firehouse which has been burning for over a century. Now if it can last that long being on, imagine how long it can last just being stored.


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## amlim (Dec 5, 2006)

i am glad to hear that the bulbs should last a long time coz my SFs are shelf queens.


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## bwaites (Dec 5, 2006)

Glass flow, if not a myth, is at least not going to be an issue with lamps!

The problem is defining glass as a solid or liquid, since it has properties of both at environmental temps. If it is a liquid, then flow becomes an issue, but experiments done by some scientists were unable to demonstrate either that glass would bend or flow over normal time frames and normal temps. 

I just love that old glass, it looks SO cool! The slight distortions, (well, sometimes they are more than slight!) give a neat outlook on normal things.

Bill


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## idleprocess (Dec 5, 2006)

I figure that glass flow - if it happens - is going to be a _very_ long shot, taking decades or even centuries to become a factor. For the sake of this discussion, if it's more than the average human lifespan it's just not an issue.


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## bfg9000 (Dec 5, 2006)

The only way glass might flow in those old buildings is from the sheer weight of all that glass. It would take more than a few millennia for gravity to affect something as lightweight as a bulb, and I'll wager we'd have something at least slightly better by then to replace them with anyway.

Of course if you are really concerned about it you could carefully rotate your lights when in storage


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## eebowler (Dec 6, 2006)

Actually, I'd think that the storage life of an LED would be less than that of an incandescent bulb because of degradation of the epoxy dome and the phosphor coating.


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## idleprocess (Dec 6, 2006)

eebowler said:


> Actually, I'd think that the storage life of an LED would be less than that of an incandescent bulb because of degradation of the epoxy dome and the phosphor coating.



Neither ought happen in storage uinless you store it at an unreasonably high temperature (phosphor degradation) and exposed to a good deal of UV (epoxy degradation).


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## Flummo (Dec 6, 2006)

A lamp that is turned on can obviously last 105 years, so one on the shelf should outlast you by a few milenniums or so as long as you store it the proper way. That is, unless your name is Duncan McLeod? :candle: (There can only be one )

http://www.centennialbulb.org/


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