Exploding Par Can...
- Thread starterchriskreidler
- Start date
So... let's turn this conversation toward safety.
Is there any way to know the lamp is about to go supernova?
How can you prevent injury?
Obviously, as has been mentioned several times in this thread, a safety screen in a PAR is a very good thing and will help. However, it will only catch the large chunks of glass. Is there anything we can do about the small chunks? Is the possibility of a supernova just a danger we have to live with? Is safety the best argument for dumping your old PAR cans and switching to S4 PARs instead?
Should we be installing safety screens in all our fixtures? Clearly, most of us assume that in fixtures like S4 Pars, Fresnels, and Ellipsoidals the lens in front of the lamp will contain the "supernova". I see very few safety screens on any of these fixtures. Is it wise or paranoid to put safety screens on fixtures with a lens?
Is there any way to know the lamp is about to go supernova?
How can you prevent injury?
Obviously, as has been mentioned several times in this thread, a safety screen in a PAR is a very good thing and will help. However, it will only catch the large chunks of glass. Is there anything we can do about the small chunks? Is the possibility of a supernova just a danger we have to live with? Is safety the best argument for dumping your old PAR cans and switching to S4 PARs instead?
Should we be installing safety screens in all our fixtures? Clearly, most of us assume that in fixtures like S4 Pars, Fresnels, and Ellipsoidals the lens in front of the lamp will contain the "supernova". I see very few safety screens on any of these fixtures. Is it wise or paranoid to put safety screens on fixtures with a lens?
ScaredOfHeightsLD
Active Member
We had one supernova during a performance last year. The lamp contained the explosion but the little tip shot through the gate...into the borrowed seachanger that was in the fixture, shattering the XG flag.
feedbackdj
Member
I had a Par 56 NSP 500 Watter blow on me just last week. The odd thing is that the filament kept burning... Just the front glass of the bulb. This was the first time this has ever happened in my 15 years in this auditorium.
Les
Well-Known Member
And why is it that the Altman 1K 6" fresnel comes with a safety screen designed to fit into the second color frame runner while the 65Q doesn't? Is the lack of color frame space in the 65Q the reason or does the lack of the extra 250 watts the 1K has make the 65Q less prone to lens breakage? Or maybe it has to do with the spring ring on the 65Q vs the clips on the 1K. This is going to bug me now!!!
JD
Well-Known Member
The quartz bulbs will keep working even when the outer glass cracks. I once had a GE 1000 watt VNSP do that on a show we had up for a season. It wasn't until the beam started to degrade that we noticed it. By that time, the aluminized coating had started to decay, so it had probably been cracked for a month! Just appeared to be something thermal in the glass. (one big crack across the front.) The old (80's) GE PAR64 VNSP lamps had a perfectly flat front.
Had quite a few lamps... 20 years now in using them out of school that worked even though the filament escaped its support and that filament was melting its way thru the outer globe of the lamp while still working.
Inspected a few arc light lamps today that had a failure by way of even if it had an inner lamp capsule, some sustained hard or local harder bump to the lamp in the support/lead in wire to the lamp was one movement in scratctching the outer globe too much that we now had a micro crack leak to the outside air. That micro crack in the outer globe was the cause of lamp failure in the end - and I inspect every lamp failure = about 0.5 million per yer in lamp failures.
Inspect thousands of failed both arc source and incandescent source lamps in their failure per yer and only seen a few of the filament type in say 20 years that say if they had an outer gobe had sufficient pressure so as to explode it if say filament and even at times arc source in being often less lamp than removal of lamp failure. Suppose in not seeing many failures in this concept I have never seen of showering glass one might expect it more common than norm. Lamp blows on your S-4 Leko and it showers glass onto the audience. Still have the 360Q on the other hand and it don't shower glass, or was that the Selcon that don't shower glass.
On the other hand, in reality should a lamp blow, the lenses and fixture and in general that fixture shoud retain all glass if it blows especially if a Leko over the audience. Minor particals excepted as per possibly coming off a damaged reflector.
Nope, never seen glass from a lamp escape and shower down on an audience. Been told about one or two PAR 38 thru 64 types that in the past have split but nothing beyond a bad lot number dangerou to who is below in hearing about.
Inspected a few arc light lamps today that had a failure by way of even if it had an inner lamp capsule, some sustained hard or local harder bump to the lamp in the support/lead in wire to the lamp was one movement in scratctching the outer globe too much that we now had a micro crack leak to the outside air. That micro crack in the outer globe was the cause of lamp failure in the end - and I inspect every lamp failure = about 0.5 million per yer in lamp failures.
Inspect thousands of failed both arc source and incandescent source lamps in their failure per yer and only seen a few of the filament type in say 20 years that say if they had an outer gobe had sufficient pressure so as to explode it if say filament and even at times arc source in being often less lamp than removal of lamp failure. Suppose in not seeing many failures in this concept I have never seen of showering glass one might expect it more common than norm. Lamp blows on your S-4 Leko and it showers glass onto the audience. Still have the 360Q on the other hand and it don't shower glass, or was that the Selcon that don't shower glass.
On the other hand, in reality should a lamp blow, the lenses and fixture and in general that fixture shoud retain all glass if it blows especially if a Leko over the audience. Minor particals excepted as per possibly coming off a damaged reflector.
Nope, never seen glass from a lamp escape and shower down on an audience. Been told about one or two PAR 38 thru 64 types that in the past have split but nothing beyond a bad lot number dangerou to who is below in hearing about.
tjrobb
Well-Known Member
Running an Altman Comet and noticed the beam going... strange. Killed the lamp mid-cue as the color went awry and noticed a crack in the 360W lamp; the lamp had nearly split in two (yes, the fans are running fine). Quite interesting, the crack runs from one side on the rim, through the base, and back up to the other side of the rim. Didn't actually fail, but I don't want to see what happens when an MR16 blows into two pieces.
waynehoskins
Active Member
experienced many lamp failures over the years but I can only remember one where the lamp shattered and it was contained in the fixture. It was caused by the fixture being bench focussed so that the reflector was touching the lamp. I am disregarding open incandescant floods where someone jammed a ladder into the lamp or droped a wrench into a ground row.
I have seen the lens come off of PAR 36 pinspots but the halogen bulb inside was fine and it kept working. The cement that held the lens to the reflector had failed but the design of the pin spot kept it all together.
I have seen the lens come off of PAR 36 pinspots but the halogen bulb inside was fine and it kept working. The cement that held the lens to the reflector had failed but the design of the pin spot kept it all together.
2 years ago this happened to me - in a ballroom for a wedding with the can used at uplight. Client seemed a little pissed and having to clean up shards of glass with guests around wasn't fun either. I was worried though because I didn't know what caused it, and realllly hoped it wasn't something I did. A phone call or 2 later no more worries.
JD
Well-Known Member
Lamps do fail, but I am surprised that the back would blow open! What type of latch or screw is used to close it?
Screens were added years ago to reduce large chunks of glass from falling out of the front. Most cans use a set screw or snap latch to lock the back. Dealt with thousands of pars over the years and never saw that happen. Although the quartz burner operates under pressure, the actual lamp envelope is usually a reduced pressure with an inert gas to preserve the reflector coating. Crack, yes. Shatter, yes. Explode with enough force to peal open the back, no, not yet.
Special Tannerite model?
Screens were added years ago to reduce large chunks of glass from falling out of the front. Most cans use a set screw or snap latch to lock the back. Dealt with thousands of pars over the years and never saw that happen. Although the quartz burner operates under pressure, the actual lamp envelope is usually a reduced pressure with an inert gas to preserve the reflector coating. Crack, yes. Shatter, yes. Explode with enough force to peal open the back, no, not yet.
Special Tannerite model?
EdSavoie
Well-Known Member
I haven't yet seen a bulb fail that violently, I've seen a number of 120v HPLs grow massive bulges from that time a teacher lamped a bunch of S4s with his bare hands... I've also seen (properly Lamped) bulbs where the filament touched the glass after failing and melted a nice bulge into it.
"It's not a tumor!"
"It's not a tumor!"
Judge
Active Member
I have seen a few PARS explode like that. No way to prevent it, it just happens. You can mitigate damage to some extent by using proper cans with safety mesh which will catch the big chunks, and always use some kind of color filter on the front which will catch most of the smaller shards.
I am sure they will be outlawed soon anyway.
If you want real fun you need to be around when a 400w UV bulb goes. They are more highly pressurized I think and literally sound like a bomb going off and spray horrible coated shards everywhere.
I am sure they will be outlawed soon anyway.
If you want real fun you need to be around when a 400w UV bulb goes. They are more highly pressurized I think and literally sound like a bomb going off and spray horrible coated shards everywhere.
Roger L. Lattin
Member
I work primarily in film and TV when a drop of liquid (sweat, water or something else) hits the lens or lamp globe it goes BOOM. For a long time when new designs were out in the field (4kW, 1kW2 HMI pars, 18kW HMI, 20kW & 24kW tungsten Fresnels) some times with just powering them down the cold night air would just cause them to blow up. There are safety screens in most of our lamps BUT, some times the globes/lenses sneak through. On some of the bigger lamps we have taken to putting doubles in them before sitting them down to allow them to cool more slowly and that usually stops the issue or contain it better;-) And some times they just go boom, we just try to make sure that even thing around them is fire retardant.
Similar threads
