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This topic comprises 4 pages: 1 2 3 4
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Author
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Topic: Xenon Bulb blowup damage the truth the myth?
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Monte L Fullmer
Film God
Posts: 8367
From: Nampa, Idaho, USA
Registered: Nov 2004
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posted 06-16-2005 03:44 AM
Yes, it can be nerve wracking when handling a bulb -from a pencil 1k type to a good size 6k bulb. For you just don't know if the thing is going to go with just holding it or what.
I remember when I changed my first bulb and that was in a Cine 1600 vertical lamphouse. Bulb had 8700 hrs on it and dark as pitch. I've heard nasty stories of the dangers of bulb explosions, so dressed up with the protective garb (hotter'n hell in that thing as sweat running from the heat and with the nerves going full tilt...). Got the allens out to loosen up the connections, got the cover over that bulb, took it outside and threw it in the driveway to bust..and the danged thing didn't even pop...just shattered from age. I was disappointed on that one....lol.
One time when I was changing out a 2k in a X-90 "Wrong" unit, I bumped the envelope pretty good on the edge of the mirror as I was pulling it out (wasn't paying attention that time), but no "pop!" - just woke me quite suddenly on paying attention to what I'm doing when extracting a bulb from a small lamphouse area. For I was still used to CHR-SLC consoles with all the room those things had when changing bulbs...and no cables to worry about with those SLC(E) consoles...
I've only had one bulb (2k Osram) explode on me, and that was during a run in an Xetron-35 console back in 1980. The anode spider that supports the front end got tweaked solid somehow and when the bulb was getting hot, exploded when it couldn't expand.
That was a noisy one-the whole cinema heard that one go off.
Many bulbs that I've changed, from the first one that took almost a half hour to do, to where I can do one in 5 minutes..yet I still get nervous on what can happen....
-Monte
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Frank Angel
Film God
Posts: 5305
From: Brooklyn NY USA
Registered: Dec 1999
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posted 06-16-2005 10:28 AM
Pirate Phil sez: quote:
NEVER trust the published/manual specs for air flow for a lamphouse! While it is very important to cool a lamp properly (the envelope as well as the seals) it's equally important NOT to over-cool the lamp!
Which, I gotta tell ya, isn't the most comforting thing I've ever heard. I mean, first I was worried about everything getting too hot because this is an outdoor venue and typically the ambient temp in that booth is like 95-100 degrees on a hot August night. I stuck this Granger fan that is built into a 8" stove pipe on top of the ORC lamphouse (4500K bulb) as an extra bit of cooling "just in case." I figured sucking out more heat from the lamphouse can only be a good thing. But here's this over-cooling issue to give me more heartburn. Do I really have to worry about this too?
Welp, nothing has exploded yet, and the bulbs are in no way distorted -- I am assuming that if the additional cooling were adversly affecting the bulb (uneven temps on the envelope?), there would be some signs of it....or an explosion, or both, whichever comes first as they say. I've seen a bulb from a lamphouse that had faulty exhaust and it had a buldge in the envelope. Nothing like that so far.
And while we are at it, bulbs that I have seen in one of the theatres were all encased in a hard plastic hinged case. The Osram bulbs that we have are only wrapped in this kind of Seran wrap thing with shoe laces attached to hold it in place. To be honest, that looks pretty flimsy to me. Can that soft plastic wrap really be any help if the bulb decideds to become a grenade? The hard plastic case looks a lot more substantial. And further, that damn plastic wrap sticks like glue to the bulb, and me being the wimp that I am, I put the bulp in the lamphouse, wrap and all. The idea being, that I want to make that time the bulb and me are together without the added barrier as short as possible. Then, once it is in place in the lamphouse, I TRY to pull the wrap off, but it's not easy -- you have to pull and tug at it because it sticks like glue to the bulb, which, as I said, being the wimp I am, is pretty damn nerve-racking.
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