Catastrophic lamp failures
- Thread startericewolf08
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I can just see that. (granted I'd be one of the people who wants to) Hi everybody, today we're going to tackle a myth that 70 percent of our viewers don't care about or don't understand! granted if they could actually make some bulb blow up and break things people would still be interested. It just seems like convincing them to do it would take a little work haha.
I remember when I was first getting involved in tech theater, we had a lamp blow. The LD was up on the genie focusing lights, and he asked me to go to the dimmer rack and bump the one he was working on. After doing so, I looked up just in time to see the thing explode, red-hot glass falling out of the front of the barrel. It gave the LD a pretty big scare.
The fixture in question is a source four. It was a new lamp, so we assumed that it had been accidentally touched. Until I saw that video, I always thought a touched lamp would explode immediately.
The fixture in question is a source four. It was a new lamp, so we assumed that it had been accidentally touched. Until I saw that video, I always thought a touched lamp would explode immediately.
techieman33
Well-Known Member
JD
Well-Known Member
Re: Suggestion for a replacement for FELs
Just looks like a regular filament sag blister pop to me. With age, the filament which is soft when on, sags due to gravity until it contacts the envelope. Envelope forms a blister where it touches. Sooner or later blister pops and filament squirts out. Saw this many times on VNSP par bulbs. Sometimes would take months before it actually went.
No idea about the yellow stuff, but it looks neat!
Not an FEL, in fact, only a 500W lamp, but of the same family and one of the most interesting lamp failures I've ever seen:
from Jim On Light .
One could speculate about this with many hypotheses.
- Since in a Fresnel, the lamp burns base down, all the heat is concentrated at the end of the envelope.
- Because of the spherical reflector, all the heat is concentrated on one side of the lamp.
- The coiled-coil filament geometry doesn't suit itself well to a spherical reflector. A planar filament, such as on the BTL family, makes much more sense. But using an EHD is not unique to Kliegl; Altman used the same lamp in some of their 6"FS (65Q) for a time.
- What chemical compound would cause the yellow powder on the inside of the envelope? Sulfur?
- What caused a portion of the filament to get sucked outside the envelope?
Just looks like a regular filament sag blister pop to me. With age, the filament which is soft when on, sags due to gravity until it contacts the envelope. Envelope forms a blister where it touches. Sooner or later blister pops and filament squirts out. Saw this many times on VNSP par bulbs. Sometimes would take months before it actually went.
No idea about the yellow stuff, but it looks neat!
Re: Suggestion for a replacement for FELs
I don't find the video very compelling. It seems to me there are a lot of variables that their tests didn't take into account. Everything from how clean his hands were, the heat dissipation of the particular lighting instrument, to the formulation of the glass, to the type and brand of the lamp. There are just a pile of factors that could affect the chances for catastrophic failure.
I think most people here would agree it's important to handle bulbs carefully to avoid problems.
I don't find the video very compelling. It seems to me there are a lot of variables that their tests didn't take into account. Everything from how clean his hands were, the heat dissipation of the particular lighting instrument, to the formulation of the glass, to the type and brand of the lamp. There are just a pile of factors that could affect the chances for catastrophic failure.
I think most people here would agree it's important to handle bulbs carefully to avoid problems.
Re: Suggestion for a replacement for FELs
I worked in my uncle's musical repair shop. When refinishing brass instruments the final step before laquer was coloring, polishing with jeweler's rouge. Most people, myself included, can't touch a colored piece of brass with causing it to turn. My uncle could handle barehanded with no problem.
Even the video agrees that it is less than conclusive but he certainly isn't advocating handling lamps barehanded. It may be as simple as he has very little oil/acid in his hands.
I worked in my uncle's musical repair shop. When refinishing brass instruments the final step before laquer was coloring, polishing with jeweler's rouge. Most people, myself included, can't touch a colored piece of brass with causing it to turn. My uncle could handle barehanded with no problem.
Gern
Active Member
Re: Suggestion for a replacement for FELs
When I got to Hollywood in the late 1980's, the first Gaffer I worked with told me his rendition of the Tungsten-Halogen cycle. He said the finger oils create a 'cooler' spot on the quartz envelope. The 'cooler' area allows the tungsten to stay on the envelope and over time less and less tungsten makes it back to the filament, finally causing the filament to break.
Around 2000, I was on a GE commercial for a month in Ohio and met some of the GE engineers who design the studio bulbs we use. I told them what I was told, and they said my version was way simplified, and that there was a lot more to it, but they agreed, it creates a 'cooler' area on the envelope.
Now, after seeing that video with him saying hotter, I did a small net search and everything I see calls it a 'hotter' area on the envelope. Hmm...
Either way, after all these years seeing globes with dark 'fingerprints' where the filament has stuck to the envelope, I 'believe' that human fingers on a halogen globe will, over time cause a globe to prematurely burn out.
When I got to Hollywood in the late 1980's, the first Gaffer I worked with told me his rendition of the Tungsten-Halogen cycle. He said the finger oils create a 'cooler' spot on the quartz envelope. The 'cooler' area allows the tungsten to stay on the envelope and over time less and less tungsten makes it back to the filament, finally causing the filament to break.
Around 2000, I was on a GE commercial for a month in Ohio and met some of the GE engineers who design the studio bulbs we use. I told them what I was told, and they said my version was way simplified, and that there was a lot more to it, but they agreed, it creates a 'cooler' area on the envelope.
Now, after seeing that video with him saying hotter, I did a small net search and everything I see calls it a 'hotter' area on the envelope. Hmm...
Either way, after all these years seeing globes with dark 'fingerprints' where the filament has stuck to the envelope, I 'believe' that human fingers on a halogen globe will, over time cause a globe to prematurely burn out.
Re: Suggestion for a replacement for FELs
Having worked in hardware for longer than I care to admit I can tell you that with consumer level halogens you can indeed get catastrophic failure by touching the lamp. I've seen more finger printed lamps come back to try and be returned because the consumer didn't follow directions.
Having worked in hardware for longer than I care to admit I can tell you that with consumer level halogens you can indeed get catastrophic failure by touching the lamp. I've seen more finger printed lamps come back to try and be returned because the consumer didn't follow directions.
JD
Well-Known Member
Ah, but the cooler area causes a hot spot! Once tungsten starts to deposit, light and heat are blocked from exiting the bulb so that area absorbs more and the envelope may fail.
Truth be known, the effect of touching a lamp may be overblown. However, with lamps costing what they do, why chance it. It just seams like good practice.
I have seen the same types of failures that are often blamed on bulb handling occur in sealed PAR64 lamps. One could postulate that the bulb was somehow handled at the factory, but I am pretty sure that is not the case.
Still, why chance it. Who wants a fingerprint on any of the optics of a fixture? Although the lamp envelope does not effect the focus of the beam, it can help scatter it.
Truth be known, the effect of touching a lamp may be overblown. However, with lamps costing what they do, why chance it. It just seams like good practice.
I have seen the same types of failures that are often blamed on bulb handling occur in sealed PAR64 lamps. One could postulate that the bulb was somehow handled at the factory, but I am pretty sure that is not the case.
Still, why chance it. Who wants a fingerprint on any of the optics of a fixture? Although the lamp envelope does not effect the focus of the beam, it can help scatter it.
Exploding 575 HPL
Had a 575 explode in one of my s4 pars. Ive had this happen before but it has never shot through the Lens. Ideas as to why this happened? We have about 20 of them hanging over our band and i can't have these lens raining down on the band. Was told that the lamp was a Pale Bright Blue right before it happened and was a loud pop then flaming glass...
Had a 575 explode in one of my s4 pars. Ive had this happen before but it has never shot through the Lens. Ideas as to why this happened? We have about 20 of them hanging over our band and i can't have these lens raining down on the band. Was told that the lamp was a Pale Bright Blue right before it happened and was a loud pop then flaming glass...
DuckJordan
Touring IATSE Member
Re: Exploding 575 HPL
it happens. if you feel uncomfortable about it put a metal screen in the gel slot. It will help keep large glass bits from coming down until you can maintenance the fixture. Honestly it happens so rarely that we even stopped doing it in our main stage space. Although we do put them in our 2k Fresnels the temperature drop from on for 20 mins to off in our space can cause our lenses to crack the screen helps the cooling curve of our lenses. Or so it seems.
it happens. if you feel uncomfortable about it put a metal screen in the gel slot. It will help keep large glass bits from coming down until you can maintenance the fixture. Honestly it happens so rarely that we even stopped doing it in our main stage space. Although we do put them in our 2k Fresnels the temperature drop from on for 20 mins to off in our space can cause our lenses to crack the screen helps the cooling curve of our lenses. Or so it seems.
JD
Well-Known Member
Re: Exploding 575 HPL
Funny how this thread comes back to life whenever there is a violent bulb blowout!
What happens is the filament sags, shorts, and the shortened section skyrockets in color temperature (and just plain temperature) before melting a section of the lamp envelope and then Ka-Boom! (under a nice high pressure.)
Most often, the failures are more of a sput-puff.... but when conditions are just right, Boom it is! That's the real thing, out of maybe a thousand failures, you may get two that actually cause something to leave the fixture. (Except for un-screened PAR lamps.)
Funny how this thread comes back to life whenever there is a violent bulb blowout!
What happens is the filament sags, shorts, and the shortened section skyrockets in color temperature (and just plain temperature) before melting a section of the lamp envelope and then Ka-Boom! (under a nice high pressure.)
Most often, the failures are more of a sput-puff.... but when conditions are just right, Boom it is! That's the real thing, out of maybe a thousand failures, you may get two that actually cause something to leave the fixture. (Except for un-screened PAR lamps.)
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