Catastrophic lamp failures

[icewolf08]

Last night during the show we heard an unusually loud gunshot like sound. It actually caused an actor to do a doubletake. It seemed too loud to be a lamp failure and we didn't notice any dark spots on stage. Well, guess what we found during channel check today:


This is the front of the lens tube and lamp from a Strand Century Axial 6x9


Here is the back of the lens tube


And the lamp

Needless to say, as the LD used every 6x9 and 36˚ unit in my inventory, we will have to come up with a solution for tomorrow's show.

[Wolf]

what would have cause the lamp to fail like that, simple as just someone had touched it?

[Spader]

Yeah...FELs go out with a bang. At our theatre here, we have an inventory of about 20 S4's and 30 Strand Lekos (Which use FEL lamps). Whenever the Lekos go out, everybody knows it. When the S4's go out, no flash, no sound, no nothing.

I just remembered:
I have a PAR64 lamp to replace this weekend because it went out this past weekend. It was really cool when it did go out, because suddenly this bright purple light filled the room.

[Footer]

I had one go out a few years ago in a 360q. It was during tech, so I was asleep in my office backstage. I hear the "shot", thought we were under attack. Then I get the page backstage saying we lost a lamp. I had to take the fixture down and completely tear it down to get all the glass out. We didn't break a lens though, thats a first time I have seen that. I have seen a Par56 explode... that was "cool"

[icewolf08]

Most of my FELs have been replaced with HX-755s, but apaprantly I missed a couple (or at least one).

[JD]

Odd that the shatter pattern is from the front of the lens inward... Sure it wasn't really a gunshot?

[icewolf08]

Odd that the shatter pattern is from the front of the lens inward... Sure it wasn't really a gunshot?

The shatter patter is on the inner of the two PC lenses in the tube, so it is from the back.

[JD]

The shatter patter is on the inner of the two PC lenses in the tube, so it is from the back.

Feisty little thing!!

[derekleffew]

Alex, why does there appear to be about a 1/8" hole in the lens tube's right colorframe clip? Picture #1 also shows the silicone lens mounts not properly evenly distributed around the circumference of the lens.

I've only cracked the rear lens in 4 1/2 x 6 1/2 fixtures using FELs. (And 360Q-6x9, but that's wrong in the first place.) Such a catastrophic failure was most likely due to an impurity in the envelope, and not an inherent flaw in the lamp design. I have had HPL575s and 750s exhibit a similar end of life, but no cracked lenses.

Needless to say, as the LD used every 6x9 and 36˚ unit in my inventory, we will have to come up with a solution for tomorrow's show.

Buy a new 6x9 lens for $65, or hang a 6x12 approximately 1.5 times further away.

[icewolf08]

Alex, why does there appear to be about a 1/8" hole in the lens tube's right colorframe clip? Picture #1 also shows the silicone lens mounts not properly evenly distributed around the circumference of the lens.

I've only cracked the rear lens in 4 1/2 x 6 1/2 fixtures using FELs. (And 360Q-6x9, but that's wrong in the first place.) Such a catastrophic failure was most likely due to an impurity in the envelope, and not an inherent flaw in the lamp design. I have had HPL575s and 750s exhibit a similar end of life, but no cracked lenses.

Buy a new 6x9 lens for $65, or hang a 6x12 approximately 1.5 times further away.

I never noticed the hole. I do the best I can with the manpower and budget I have to keep these fixtures running. They do pretty well, however, they have seen better days. I have done the best with the gear that I inherited when I took this job. Every year I take the worst of the fixtures out of service and replace them with Source Fours (about 4-10 each year depending on funds). Once out of my inventory, I give them to the Theatre Department here at the U. Most of them work very well despite the fact that they look like they have been Frankensteined together!

[ship]

Or at least take these photos to those that do the budget and say you would like to go GLC or GLD for high output or GLA or GLE for long life with similar ouput. It's a safety issue as long as you don't tell them it's more of a fluke of filament failure and rare.

That's an amazing "Kill Roy Was Here" failure as I named such a thing when the filament of the lamp explodes out the side of the globe as if gunshot with the glass lingering in cooling as if held in slow motion in how it bent out to reflect the escape of the filament.

Most likely on the opposing side of the lamp you will also see a puckering of the glass as the gasses in the lamp were sucked out. This shape of the puckered/sucked in glass in the case of an incandescent lamp I noted with a filament gunshot thru the globe, formed a "Kill Roy Was Here" shape on the sucked in side of the glass. Thus the name for it I have.

Most likely, it wasn't due to touching the lamp as initially assumed, just normal halogen cycle in depositing tungsten particles on the hottest part of the lamp - the center of the filament, and for some reason as opposed to a normal failure, that filament in where it broke and going arc lamp or as I call "super nova", it flying out the side of the globe in that instant of while it's super nova. Given a halogen effect, that doesn't mean that spent tungsten particles near the edges of the hangers or lead in part of the resistant filament gets a re-deposit of tungsten on it as spent, instead it often just goes to the center of the filament in while it takes longer on halogen lamps to wear out than on non-halogen, incandescent lamps to wear out, still towards the filament supports or lead in wires of a halogen lamp, it can still wear out without replentishment. This area in a micro second often is also in normal and not shock where is where once broken an arch of current will develop until the resistance to current flow is too much to continue with that much brighter now in being a arc light intensity.

Given the power of that instance of it being an arc light, there becomes at some point so much pressure that there can be a blow out of the filament given all support and lead in wires for it have not had sufficient replentishment of them so as to support them while going super nova arc lamp as it were. At that point that filament resistor following the arc of current no doubt starts flopping wildly in explosion and should it escape during this also period of intense heat, that's about the end result. If nothing else, that's a lamp that lived well past it's expected lamp life if not got a shot of voltage in failing. Normal failure just under conditions where the amperage applied to it was sufficient to continue completing the circuit even if no longer connected to power source. Bang! within a micro second that filament escaped and the light goes out.

Rare and wouldn't be worried about happening, nor in this case it would seem did the fixture other than protect the audience or talent below as designed should it happen. Wouldn't tell the management it's other than a problem and we need to change lamps given the lamp in use, but realistically there was no safety hazzard. More just an excuse used to change to a better lamp.

The FEL ain't rated for most fixtures and even if rated for it, your's ain't efficient in using them as opposed to other lamps more recent to the market. It's a selling point for more efficient lamps budgeted for next year.


Go with it in selling it even if not normal to be a problem. In the end... Killroy Visited You as it were. It's rare and spectacular ain't it.

Get rid of them FEL's for other reasons than this filament spectacular escape.

[mrb]

I bet this was a combination of factors, the lens not seated properly in the tube with the misplaced silicone pieces + tremendous heat from using 1K lamp = lens under stress, and the exploding lamp was enough to make the lens fracture. Kind of like how a piece of tempered glass under stress will explode with a gentle tap.

[church]

unusual failure because these fixtures use two lenses with the curved surface touching. The 6*9 barrel actually uses two 6*9 lenses which at their centre are approximately 1.75 inches thick. However lenses used in stage fixtures include voids from the manufacturing process which don't affect their performance in this application. these voids in conjunction with stress from uneven lens mounting and even micro stress cracks from the fixture being moved and knocked may create the conditions for this type of problem.

If I was doing a failure analysis on this my hypothesis would be that as the shock wavefront resulting from the expanding halogen gas released by the rupture in the quartz envelope expanded through the focal gate and reached the first lens causing this lens to shatter and because there is only about 1/8 of an inch between the lenses one or more bits of gllass hitting the second lens causing it also to shatter. I have seen this type of failure on optics before in optical instruments when we have applied accoustic shock waves to them.

Fortunately the reflector is metal - if this had been a S4 you would probably also need a new reflector.

This can happen with any halogen lamp - the manufacturers include a caution on the lamp failure in every box. A FEL, GLC, GLA, HPL and any other halogen lamp can all produce a failure like this - fortunately it is very rare. All the halogen lamps contain a gas at a similar pressure - if they don't they don't work because the halogen cycle controls this. The variables include the filament temperature, filament size, quartz envelope size

Replace the lenses and the lamp and return to service.

I recently cracked a lens in a colortran zoom using an FEL. Brought the fixture indoors after it had sat for a few days in my van at -20 degrees centigrade, clamped to a pipe and after 30 minutes turned it on and heard the crack after only five minutes of operation. Differential rates of expansion of materials cause real problems when fixtures are cold like the one I had. Normal room temperatures are not normally a problem. But the failure was caused by my not allowing enough time for the fixture to reach room temperature before turning it on - not that the FEL the fixture or the lens was faulty.

[icewolf08]

The FEL ain't rated for most fixtures and even if rated for it, your's ain't efficient in using them as opposed to other lamps more recent to the market. It's a selling point for more efficient lamps budgeted for next year.

Go with it in selling it even if not normal to be a problem. In the end... Killroy Visited You as it were. It's rare and spectacular ain't it.

Get rid of them FEL's for other reasons than this filament spectacular escape.

As I mentioned, it is probably a fluke that this unit still had an FEL in it. I have only stocked HX-755s for these fixtures for the past two seasons (mostly thanks to your recommendations). However, I would take this to management with the pitch that the fixture is at fault to see if they would give me the money to replace the last 45 in my inventory.

And yes, other than this being very cool and kinda pretty, it was certainly a great example to use as education for my crew. I have seen some pretty spectacular lamp failures, but most of my crew had never seen something like that. Par of my wants to fill the lens with epoxy and keep it as art (and an educational piece).

This can happen with any halogen lamp - the manufacturers include a caution on the lamp failure in every box. A FEL, GLC, GLA, HPL and any other halogen lamp can all produce a failure like this - fortunately it is very rare. All the halogen lamps contain a gas at a similar pressure - if they don't they don't work because the halogen cycle controls this. The variables include the filament temperature, filament size, quartz envelope size

Replace the lenses and the lamp and return to service.

I am aware that this can happen to any lamp, I have seen HPLs go out in some pretty spectacular ways. It is fortunate that it is rare, it just seems less rare in FELs. As for replacing the lens and returning to service, that is easier said than done on account of I have no more 6x9 lenses. It isn't worth me buying a lens for these fixtures as I am already planing to retire and replace 4 of them. I do have 6x12 lenses for them, so this unit will live to see another day. If this had happened to a source four, I would have a new lens here tomorrow, these fixtures just aren't worth much more than the time it takes us to service them each year.

[JD]

What I remember with those FELs is that the filament would sag until it was close to the quartz, which would start to bubble out. Use to see the same thing in some par bulbs that didn't use center supports. I used a lot of VNSPs where it is very visible because of the clear front. I can remember rotating lamps whenever I saw any sag starting. Can't be sure it ever extended any life and I never really kept track.

[cdub260]

Par of my wants to fill the lens with epoxy and keep it as art (and an educational piece).

Do it. This would be a cool thing to keep around, especially if you make the fixture a part of that art/educational piece.

[lieperjp]

Do it. This would be a cool thing to keep around, especially if you make the fixture a part of that art/educational piece.

Make it into a table lamp! Erm... maybe not.

[derekleffew]

Alex, you need to post your lens picture here.

[church]

When I was preping some fixtures to go out on rental I found a HPL 750 about to self destruct lloked very much like Derek's above but with a bubble in the side of the quartz envelope. The lamp was still working but I removed it and stuck it in the garbage before it destroyed a lens or reflector. As I pulled it out the envelope seperated from the base. This was a new lamp with less than 10 hours on it. When I checked the lampholder I found one of the contacts was also burned to a crisp.

[thatactorguy]

Alex, why does there appear to be about a 1/8" hole in the lens tube's right colorframe clip?

My guess is that the hole was for a self-threading screw or some sort of pin or clip to help hold the gelframe in place if the instrument were hung in such a manner that there was a chance of the frame coming out. Just a thought...

[Esoteric]

Well, I had that happen during a show. Only it totally blew the glass out and on to the actors who were having an intimate moment on stage, raining glass down on them. They didn't even flinch.

Mike

[venuetech]

I was doing a lamp check once when one foh unit failed just as i was about to move on to the next channel, it had burned around thirty seconds. i finished the check, got a spare FEL and went up to the catwalk. unplugged the unit pulled the head and inspected the lamp. just a normal blown lamp, slightly warm i just grabbed it and removed it from the socket, set it down on the deck, then turned around to get the spare that i had behind me, BAM!! the old lamp blew as i faced the other direction. the base was the only thing left of the lamp.

no more warm lamp changes for me.

[LeChivre]

Wow I had something like this happen to me last summer back at USF. I hate FEL's but no where near as much as I hate FLK's. Now those really fail!

[Edwinlq1go]

I have been trying to locate any info (IE: data-sheet, cut-list) for the unit pictured in the above post. I have 8-6x9 units and 8-4.5?x9? units. Any help would be greatly appreciated.

[llecount]

What's the word around here on SPH lamps as a replacement for FEL's? Our supplier recommended them to me for our Lekolite 10x23's.

[derekleffew]

Edwinlq1go, 4 1/2 x 6 1/2, ie., 50° units. Here's the cut sheet for the 1977 Strand Century Lekolite #2321, 6x9, (oops! wrong generation). See Strand Archive - Leko Range in the Strand Archive. 6x9 was SC#2209 and 4.5x6.5 was SC#2204.

[NevilleLighting]

Every once in a while a lamp blows, just does. That is why most PAR's have a screen. Technically every lamp is supposed to have something between it and the stage, even if the something is a clear gel, although I have no idea what a gel is going to do to stop glass shrapnel. Many PAR's predate the screen requirement and I did get to see one blow during an invited dress with about 800 people in the audience. It showered red hot glass down on to an actress. She kept going but we stopped the show to remove the rest of the broken glass.

[ship]

What's the word around here on SPH lamps as a replacement for FEL's? Our supplier recommended them to me for our Lekolite 10x23's.

Have not tried the SPH 575/115 lamp yet. Got them to play test but have not had time yet. A quick warning went out to me in that lamp's advertising on the other hand: "20% brighter in Par & some" Lekos. That beats the estimate of the now discontinued Osram HPR lamp in being 15-20% brighter in Lekos due to its internal reflector completing the ellipse of the reflector, but on the other hand look at the language Ushio uses. Brighter in PAR and "Some" Lekos. That's a red flag for me before testing in if it says "Some" Lekos... what brand of Leko is it brighter in?


Again have not tried it yet verses the GLC or GLA and what sock I still have in the HPR. This much less verses a GLD and GLE lamp. Could be great but on the other hand in a simple way if you insert a reflector so as to complete that black hole for light inside a reflector assembly I can see a boost in efficiency in the lamp's output. If my lamp specification says on some Lekos it's going to be brighter... my qestion is not as much about how now 20% brighter (fill in the blank as to what in comparison in me not remembering), more simply about that word "Some" as stated in the specification.

While the luminous output of the SPH lamp is 1,000 lumens more than a GLC lammp on paper, I would still ask the vendor to provide both lamps in shoot out with color meter to prove what the assurt given the specifications don't provide this info sufficiently to support their claim. In other words, make the sales person work for his or her profit margin.

Me, I don't know yet in not having tested such lamps. I do know that the Osram lamp now is supposted to be as good as the Philips GLC lamp in them having done an upgrade to it. GE/Thorn in specification seems low in what's published in output for the lamp.

Beyond all this, and way back on the forum back to HX-600 lamps as compared to FEL lamps, the HX-600 lamp at 575w/115v as compared to a FEL at 1Kw/120v is like a 800w lamp at a higher color temperature as compared to a 1Kw lamp at a lower color temperature.

Same though with better optics with a HPL lamp. Not persay more light and indeed a FEL was a terrible in efficiency lamp, more about that higher color temperature in making it seem brigher than the FEL.

For actual output one more would want to go with a 750w/115v lamp in getting close to output but with more refinened filament so the light produced gets out of the fixture in being brighter plus having that higher color temperature. On the other hand, if one can have less light and be satisfied, that's another fixture per dimmer you can install on it and go with the 575w lamps. Stages are too bright these days most often anyway. The FEL for instance is not designed for a 360Q, while it could be used in say a less efficient fixture so as to pump out enough light.... not for a 360Q and to some extent while it in a 360Q
did pump out a bit more light it also trashed more and more fixtures in doing so.

This heck, I got this 1.2Kw lamp that will function in a 360Q or other fixture for sheer output. Filament ain't very refined but one can use in in being powerful enough granny needs to wear shades when coming to the show.


So the above question of the SPH lamp... Go Ushio if it's better than a GLA in not having to go GLD in wattage, but on the other hand I would play test such a theory given the advertisement. Goal is more output and a higher color temperature and efficiency so as to make it seem more intense yet, but still get say four fixtures per dimmer. That's the goal in not having to exceed more and more in excess. Sure say a 750w lamp persay if competing with moving lights or 1Kw lamps in general but if on stage hopefully the 575w lamp if not the long life version of it is sufficient.

Compared to what often the qestion in "percieved" intensity.

[TimMiller]

whenever a lamp says its brighter 2 flags go off in my head. To actually make a lamp brighter, you produce more heat, or you shift the color temp to make it appear brighter. So which is it?

[derekleffew]

...To actually make a lamp brighter, you produce more heat, or you shift the color temp to make it appear brighter. So which is it?

OR, (hopefully as in the case of the SPH) the filament geometry more closely resembling the "theoretical point source" makes the fixture more efficient. That being said, I've yet to see a lamp beat an FEL in delivering footcandles to the stage in a Strand Lekolite 2123.

[ship]

whenever a lamp says its brighter 2 flags go off in my head. To actually make a lamp brighter, you produce more heat, or you shift the color temp to make it appear brighter. So which is it?

Balance in general between color temperature and luminous output in being more given voltage but lamp hours being less for the most part in concept in balance. Four things to balance for the most part in lamp design.

That's in general for lamp design on the other hand. When a lamp is designed for a lighting fixture on the other hand such as the HPL lamp or the new 1Kw AlumiPAR lamps designed for PAR 64 fixtures I was told are TBA to the market really soon, in those cases it's less about the above standards in a filament can only get up to like 3.5K or 3.6K in output before melting thru out of limitation before one considers, yes you have a filament and it has X amount of output as its own limitation before some liquid filled halogen/xenon fluid works with the filament lamp in allowing the filament to operate a higher color temperature and luminous intensity as per projector lamps already using such concepts.

What the HPL lamp and in general grid or stacked filaments allowed in given current limitations of the above voltage, output, colortemperature and lamp life did for the industry was an addition of smaller fillament cubic size needed for what was stable in design otherwise in working. Instead of a linear filament, we get a stacked filament or one on a grid that is designed with high technology so as to prevent arching between filament coils but also small enough in size that you get closer to that "Point source of light" design concept with any Leko ellipsoidal reflector spotlight.

That's the basics in lamp design. Lower the voltage of the lamp to more match that found at the fixture after voltage drop, lower the lamp life some and smaller the size of the filament and you get the HX-600/HPL lamp technology for the most part. More light gets out both by way of smaller cubic area of point source of light and operating voltage of the filament in operating at a closer voltage to what the fixture is seeing in reality.


The HPR lamp while a bad design in going FLK instead of more efficient filament GLC was an interesting design development none the less even if mistake. Such a lamp had a reflector inside of the lamp much like that of the FEL/R lamp that's long discontinued but also had an internal reflector. Such lamps and filaments were what they were but they had a reflector inside the lamp that sort of filled in that hole inside the reflector taken away from the reflector needed to insert the lamp within. It was in adding efficiency without heat if not even removing some lost heat, a more efficient but I'm told very difficult thing to do in adding this simple reflective plate into the lamp.

Still though there is ways to add to lamp efficiency.. Xenon gas goes further in allowing for a higher operating temperature within the lamp. Many halogen lamps already have the xenon gas within it. Some way of doing a liquid filled halogen/xenon filament lamp makes lamp makers sweat in their sleep in instantly asking about who is doint it already I think. Smaller filament cubic areas than next after completing the ellipse.

Found it fascinating recently an article about tubular lamps like work light T-3 4.11/16" lamps that instead of needing a bunch of filament hangers for them, they found a way to instead pinch the globe of the lamp to support the filament instead to support the filament. There is technology out there and no word on GE's appairent two year old upgrade to the HPL, but all is coming, much less many manufacturers count the days until the pattent on the HPL is gone before they both improve it and improve all lamps.


SPH potentially good. Try it. I don't know.

[llecount]

I've got 7 of them (SPH's) sitting in my office right now. I'm just as curious how they'll perform.
I can post pictures of the differences between the 2 lamps if I can get them to turn out decently.

[derekleffew]

Please do. We love pictures and shoot-outs. But it might be best to post your results to this thread: http://www.controlbooth.com/forums/l...volt-lamp.html.

[Drueke]

Hi,
I read this thread yesterday and joined today to get some advice.

I just purchased 2 (very used but in good condition) Strand 2212s that came with FELs. Their application will be front lighting in a music school performance space. The throw is probably about 20-25 ft. They will be mounted in the back corners of the room around 11ft off the floor. They will be gelled w. something like pale amber or pale pink.

500w would probably be enough and I could put them both on the same circuit (different dimmers) however 750w would give me some 'headroom.'

What is the recommendation for a replacement. Longer life is good.
Thanks,
Ray.

[derekleffew]

Either of these would be fine.
ANSI Watts Volts Temp Life Lumens Price
GLA 575 115 3050 1500 13000 $18.25
GLE 750 115 3050 1500 17400 $25.90
Compare with the first generation of this lamp family.
EHD 500 120 2950 2000 10450 $17.16
EHG 750 120 3000 2000 15000 $15.55

[gordonmcleod]

It was at one time recomended that axial lamps be rotated periodically 180 degrees to reduce filament sag
If you want to here a good bang be around a watercooled 15KW xenon when it decides to expire

[derekleffew]

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?

[zmb]

Consider that the lamp would contain a halogen (Flourine, Chlorine, Bromine, or Iodine), it could be a reaction between one of those with possible skin oils if someone did a bad job changing the lamp or some other foreign item that cause the yellowness to occur.

Indeed, a very strange lamp failure.

[Grog12]

[*] What caused a portion of the filament to get sucked outside the envelope?[/LIST]

Since explosive decompression has time and time again been disproved by Mythbusters one can assume that it was explosive compression that blew it out of the lamp as opposed to it being sucked out.

[derekleffew]

...has time and time again been disproved by Mythbusters ...

Speaking of the busting of myths, some may find this video enlightening.

stagelightinc's Channel - YouTube