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Author Topic: Xenon Bulb blowup damage the truth the myth? Randy Stankey Film God Posts: 6539 From: Erie, Pennsylvania Registered: Jun 99 posted 06-17-2005 04:15 PM                     I just kinda' figured that plastic condoms on xenon lamps worked because of our friend, Isaac Newton's laws. i.e.: If the pieces of glass are contained before they gain momentum AND if the force is spread out over a larger area, it takes a much less substantial piece of material to stop them. Thus, I never really spent much thought about the fact that a plastic wrapper APPEARS flimsier than a hard "clamshell". Furthermore, in my booth, if the xenon lamp isn't in its box, with all its packing materials and wrapped in its plastic cover (whatever form it takes) and placed securely on the shelf behind closed doors it will be actually INSIDE the lamphouse in operating configuration. Other than the actual process of replacing a a lamp, there IS NO in-between. I have seen a few xenon lamps break and have seen what they can do. No, they are NOT like hand grenades waiting to go off but shards of glass flying toward your face at supersonic speed is not a fun thing to think about, much less have happen to you. Just give them the respect they deserve.  |  IP: Logged Aaron Mehocic Jedi Master Film Handler Posts: 804 From: New Castle, PA, USA Registered: Jun 99 posted 06-17-2005 04:42 PM                     In 14 years I've only had two bulbs explode that I've installed, but neither went during my shifts. The worst explosion I've personally encountered was a ORC 2K that blew while I was removing it. Had I not been wearing my prescription eyeglass I think things would have been a lot worse. There were shards of glass from the bulb in my eyelashes. I've worn protective equipment during every bulb change since that night, and would you believe a former co-worker actually poked fun at me when I did. He went to another theatre and was eventually fired.  |  IP: Logged Andy Muirhead Master Film Handler Posts: 323 From: Galashiels, Scotland Registered: Dec 2000 posted 06-17-2005 06:44 PM                     Never actually been there when one went, in fact in 10 years I only had one explode, but it took out the mirror. quote: I can also see how removing it after the bulb is installed might lead to reflector damage (to say nothing of _not_ removing it prior to striking the bulb!). A long time ago, my chief at the time accidentally left the protective cover on after changing over a bulb, naturally enough killing it on striking! He said it was my fault as I should have noticed! He was joking (I think!). Funny now, and actually funny at the time, despite the fact it was £500 down the tube. A great man.  |  IP: Logged Frank Angel Film God Posts: 5305 From: Brooklyn NY USA Registered: Dec 1999 posted 06-18-2005 12:58 AM                        OK, I feel better about the saran wrap condom thing -- and yes, if it does hold, then great, I get that much more protection because it's between me and the bulb all the way into the lamphouse. I like that. I just have to get used to tugging at the show strings and having to peal the wrap off the bulb. Today I got the wrap unstuck before I got it into the lamphouse and it made it a bit easier. So now what about that extra fan on the exhaust? Could I be over-cooling it? I am thinking, no because nothing untoward has happened so far and they have been running for about 24 hours of film runtime and they the bulbs look fine. These bulbs have to come out and go back in to the lamphouse every summer when the projectors are installed and then taken town from the projection tower, so there is a lot of handling (hence my nervous concern as it is me who always has to do it.) Someone tell me I can stop worring about too much cooling.  |  IP: Logged Bernard Tonks Jedi Master Film Handler Posts: 619 From: Cranleigh, Surrey, England Registered: Apr 2001 posted 06-18-2005 04:30 AM                     Frank, As an extra precaution you could always make use of Christopher Duvall’s outfit. I think the visor would even fit over the helmet. Running magnetic could be a problem though, and you might have to visit a hospital first to get degaussed! Just a thought. A cinema I know well that runs with 2k xenon's, by overcooling reduced lamp life. Some Osram bulbs were only doing a few hundred hours until the problem was solved.  |  IP: Logged Jack Ondracek Film God Posts: 2348 From: Port Orchard, WA, USA Registered: Oct 2002 posted 06-18-2005 04:16 PM                        quote: Frank Angel Someone tell me I can stop worring about too much cooling. I never thought that cooling was that lamphouse's biggest problem. In any case... there were two models. One had a taller shroud on top, and a bigger squirrel-cage blower up there, which might be something to consider. Do you know what the cfm rating is on that stack blower you have? I rather doubt you could overcool an ORC lamp with anything you could insert in the stack.  |  IP: Logged Louis Bornwasser Film God Posts: 4441 From: prospect ky usa Registered: Mar 2005 posted 06-18-2005 04:49 PM                        My take on "overcooling" is that it is urban legend. I have seen so much cooling that turbulence is created near the bulb which is "unsuccessful" in bulb cooling. In any event, you must turn off the booth exhaust blower when you clean to keep the cleaning towel from being sucked from your hand in the theatres I equip and bulb life is very good (almost too good.) Louis Louis  |  IP: Logged Robert Harrison Expert Film Handler Posts: 239 From: Harwood Heights, Illinois, USA Registered: Jun 2005 posted 06-19-2005 03:14 PM                     I used to be so afraid of a bulb exploding that I had a tech do the bulb changes. He never used any protection, by the way. Perhaps because of that, I finally got comfortable with it, using only a face mask. Now, I'm thinking of getting a space suit because it's bulb changing time again! I must pass this on. I heard a story about a guy who decided he wanted to keep the ends of a bulb and proceeded to remove them with a HACKSAW! Yes, it blew up in his face. How badly he was hurt, I don't know. Also, one of techs from years back had one blow up on him when he wasn't using protection. He had some scars on his face.  |  IP: Logged Louis Bornwasser Film God Posts: 4441 From: prospect ky usa Registered: Mar 2005 posted 06-19-2005 08:34 PM                        I don't typically use protection either....this is a bad example. I am EXTREMELY careful not to put any stress on any part of the bulb. Obviously a hot bulb is more potent than a cold one. One war story: XBO-2500w/hs was thrown 75 feet against a block wall at a drive in; it did not break. I was afraid to disturb it so I hurled concrete blocks at it from a distance. When it finally blew, I was running away, and had gained some distance, maybe 45 feet. A large piece of quartz passed me by, still gaining altitude at 6 feet above the ground. Luckily it clearly missed me by AT LEAST 2-3 feet. louis  |  IP: Logged John Walsh Film God Posts: 2490 From: Connecticut, USA, Earth, Milky Way Registered: Oct 1999 posted 06-19-2005 09:28 PM                     You would have to be completely, totally, and absolutely crazy to not at least wear a face shield while changing a bulb. It makes no difference at all whether the bulb is hot or cold, new or old. Part of the problem with bulbs is that they are pretty good at not blowing up .. lulling people into a false sense of safety. I saw a guy once trying to get an adaptor off the anode end by twisting the whole thing, like you would to get a cork out of a bottle. A problem I've been seeing more often is where the heavy anode falls off the end. In the photo below, I think the anode actually wedged itself onto the "hole" it created when it fell off. This may have prevented the air from rushing out, and the bulb exploding.  |  IP: Logged Sam D. Chavez Film God Posts: 2153 From: Martinez, CA USA Registered: Aug 2003 posted 06-20-2005 12:15 AM                       The thought of Louis running is pretty funny in itself.  |  IP: Logged Monte L Fullmer Film God Posts: 8367 From: Nampa, Idaho, USA Registered: Nov 2004 posted 06-20-2005 12:35 AM                     quote: Louis Bornwasser Obviously a hot bulb is more potent than a cold one Yessir, they is. Especially when you bust a rather warm 6k that died during a soldout performance, even with letting the ends cool down for changeout. Put that bulb in it's clamshell protector and tossed it down the booth stairs to destroy. What a "Ka-BOOM" that big bulb made, plus the concussion shockwave coming from that explosion wasn't bad either. -Monte  |  IP: Logged Tommie Evans Expert Film Handler Posts: 116 From: Birmingham, West Midlands, UK Registered: Sep 2004 posted 09-17-2005 01:17 PM                     Here is Osram's new blast jacket covering a 4Kw lamp. It is strapped to the lamp by two velcro belts at each end. The jacket can be kept on during the whole changing process and gently removed once the bulb has been installing and both connections tightened. Due to the lack of space the jacket fills it will slide into most of the smallest reflector openings. During a training seminar the spokesperson dropped a used lamp from waist height - it made a pop similar to a paper drinks carton being stamped on (come on! everyones heard one as a kid ) but nothing got though the jacket. However, the bang it did make sure made me concentrate a lot harder the next time I changed one.  |  IP: Logged Marin Zorica Jedi Master Film Handler Posts: 671 From: Biograd na Moru, Croatia Registered: May 2003 posted 09-17-2005 02:01 PM                     Did you get that cover with new bulb or you get from osram??  |  IP: Logged Monte L Fullmer Film God Posts: 8367 From: Nampa, Idaho, USA Registered: Nov 2004 posted 09-17-2005 04:06 PM                     Wonder if that OSRAM cover has a Kelvar inner coating of sorts...especially, for a 4K bulb since they can be a bit nasty when they go. - Monte  |  IP: Logged

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