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Topic: Xenon off or on?

Matthew Nock
Film Handler

Posts: 82
From: Bairnsdale, Victoria, Australia
Registered: Jan 2003

posted 04-23-2003 09:15 AM

What is everyone's opinion on turning off their xenons between sessions? for example, if you have a 5 minute turn around, are you turning the lamps off? or leaving them on? how about 15 minutes? half an hour?

generally, at both theatres I am working at at present, we work on if its more than half an hour, the bulb is turned off, if not, then we leave it on.

Does continuously striking throughout the day shorten the life at all? obviously a better lamphouse (such as the nice ones on our Kinotons') will make the lamps last longer anyways...

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Ray Bernardi
Expert Film Handler

Posts: 120
From: Antrim, NH, USA
Registered: Feb 2003

posted 04-23-2003 09:33 AM

For better or worse, we shut down at the end of every run. Even if we are setting up and going again right away.

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John Hawkinson
Film God

Posts: 2273
From: Cambridge, MA, USA
Registered: Feb 2002

posted 04-23-2003 09:44 AM

This has been discussed a fair bit on these forums...it would be worth doing a search and digging up some pointers to other threads and linking to them. I don't have time right this moment to do that, but I can offer:

Over in Spots developing on Osram bulbs I cited Osram's publication Technology and Applications: XBO Theatre Lamps, which is a very good reference on the subject.

In reference to Matthew's question of how long to turn off,
Osram has this to say, on page 27 under "Operating Duty Cycle":

quote:

The average life specification for high-wattage XBO lamps refer to a burning time of 90 minutes per switching operation, in accordance with typical operating times in modern theatres. If intervals are short (less than 20-30 minutes) it is advisable to leave the lamps burning, or to operate them in standby mode at the current control range minimum in cases where the lamp current can be adjusted. See the previous section for relevent information. This type of operation also has the advantage that the greater arc instability ni the first minutes of operation of a still cold lamp does not occur, and that there is no possibility of ignition pulse interference in the sound equipment.

So, Ray, re-striking with a 5-minute turnaround is definitely a bad idea. I think you'll find everyone here who runs 2k changeovers on this site leaves lamps hot for the whole show, but there's some variation with respect to 6k changeovers. That's what you'd expect for a time of 30min.

In regards to Matthew's question, "Does continuously striking throughout the day shorten the life at all?" the answer is definitely. It's also more difficult to strike a warm bulb, though it may less bad for the bulb. Osram says (same section):

quote:
XBO lamps have their higehst life expectancy if once switched on they are not switched off again. Every additional startup, especially from cold, shortens lamp life. This is beacuse in cold ignition--and in this context this means everything more than 5 to 10 seconds after switching off the lamp--the high startup current needed to set up and ignition path must be handled by the cathode in its cold state when its emission capability is very limited. This torture erodes the cathode tip (tungest particles can be split off) thus altering its robust surface, and sudden local overheating can cause depletion of the doping material added to the tungsten in teh cathode to improve its emission capability. At an impoverished cathode the arc wnders restlesly to and fro searchnig for the lpace where emission cnoditions are best, without ever finding it.

Hope this is useful.

--jhawk

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Bill Gabel
Film God

Posts: 3873
From: Technicolor / Postworks NY, USA
Registered: Jan 2002

posted 04-23-2003 10:44 AM

I leave them on for the whole show, I run 2K change-overs. The
only time they go off is if I have over 70 minutes between shows.
Or when we run video. I'm in a Studio Post-Production operations.
Some days they stay on from 9am to 10pm. We have tobe ready if a
client books time.

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Mike Perju
Film Handler

Posts: 90
From: Toronto, Canada
Registered: Nov 2002

posted 04-23-2003 11:45 AM

The rule of thumb is that every strike shaves about 20mins. off a bulb's life... so if your intermission is anything under 30mins, it's really not worth killing the bulb.

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Sam Hunter
Jedi Master Film Handler

Posts: 779
From: West Monroe, LA, USA
Registered: Jan 2002

posted 04-23-2003 11:53 AM

So in my instance if I run a show at home and I using one projector with 6K reels then I would be better off closing the lamphouse dowser doing the new reel and starting up/ opening dowser. Guess I need to invest in a zipper so that my homemade automation will work.

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Michael Schaffer
"Where is the
Boardwalk Hotel?"

Posts: 4143
From: Boston, MA
Registered: Apr 2002

posted 04-23-2003 12:48 PM

I have thought for a long time that it might be a good idea to have the possibility to warm the cathode up before striking the lamp the first time every day or after a long break. But this would of course involve additional costs to the equipment - while it would probably save costs in the long perspective. And it would make operating it in a typical modern theater environment "more complicated" for those untrained freshly-in-from-the-street operators we have everywhere now.

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Paul G. Thompson
The Weenie Man

Posts: 4718
From: Mount Vernon WA USA
Registered: Nov 2000

posted 04-23-2003 02:23 PM

It depends. Electrical cost savings vs. lamp life. Unless you have quick turn-arounds, turn it off.

Remember one thing.....at the end of the show, the projector shuts down and the CO douser will close. However, if you do not have a device to automatically close the hand douser, you run the risk of damaging the projector shutter or the CO douser blade.

If there is a knucklehead running your equipment, it is just better to have the lamp shut down at the end of the show.

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Manny Knowles
"What are these things and WHY are they BLUE???"

Posts: 4247
From: Bloomington, IN, USA
Registered: Feb 2002

posted 04-23-2003 03:33 PM

For safety reasons our systems are set up to extinguish the lamp when the dowser closes just before tailout or, in some cases, when the motor cuts out after tailout.

From where I sit, the days of professional projectionists are over. The money saved by hiring one youngster to run half-a-dozen screens makes the "shortened lifespan" a non-issue.

As Paul G. mentioned above -- despite our efforts to attract and train good staff -- we do occasionally end up with a knucklehead in the booth.

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Dennis Udovich
Film Handler

Posts: 71
From: Sheboygan, WI, USA
Registered: Dec 2001

posted 04-23-2003 07:45 PM

The rule of thumb is that every strike shaves about 20mins. off a bulb's life... so if your intermission is anything under 30mins, it's really not worth killing the bulb
Guess I'm doing this all wrong..... We have Strong lamphouses, burn mostly 2000w Osram lamps, shut down between all showings, and most of my lamps last OVER 3000 HOURS! I don't think we'll change anything.

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Gordon McLeod
Film God

Posts: 9532
From: Toronto Ontario Canada
Registered: Jun 99

posted 04-23-2003 08:32 PM

Actually it is probably closer to 1 hr per ignition
I always leave the lamps lit between reels

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Matthew Peters
Expert Film Handler

Posts: 179
From: Glen Waverley, Melbourne, Australia
Registered: Nov 2002

posted 04-24-2003 06:09 AM

At the theatre I work for, the lamps are struck in the mornings prior to the first show for each cinema. They are left on virtually all day, until closing time. The average time between sessions is fifteen minutes, sometimes longer.

Even when a show has been cancelled because of nil audience, the lamps are left on. My last no-show was a few weeks ago – Standing in the Shadows of Motown. So the lamp would have been left burning for 2½ hours. (15 min pre show intermission + 2 hour feature + 15 min pre show intermission ≈ 2:30).

Turning off the lamp even when there is a no-show would cause complications because striking sometimes causes air-conditioning units and the dimmer unit to stop responding.

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Don Furr
Jedi Master Film Handler

Posts: 509
From: Sun City, Ca USA
Registered: Nov 2002

posted 04-24-2003 07:03 AM

I operate a pair of Super Lume-X's at the Rialto in downtown Atlanta....special screenings, film festivals, etc. Both lamps go on at showtime 1pm and go off at midnight (approx). Can you imagine shutting down the lamps between every changeover?? Last show I run 57 reels of films....let's see....57 bulb strikes!!!!
Leave the bulbs ON!

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Scott Norwood
Film God

Posts: 8146
From: Boston, MA. USA (1774.21 miles northeast of Dallas)
Registered: Jun 99

posted 04-24-2003 08:06 AM

I'll echo the other comments here.

For changeover shows with 2000' reels, I leave the bulbs on (except with Kinoton projectors where that's not possible in the standard configuration). I haven't run changeovers with 6000' reels for a while, but I usually turned the bulbs off between reels except for "important" shows.

For a single-screen house with platters, I'll leave the bulb on all day, too. I usually run this type of show manually, even if the theatre has some form of automation.

For a multiplex with platters, I let the automation turn off the bulbs at the end of each show. I'd rather lose some bulb life than melt a changeover blade or shutter because there was no operator to close the hand douser between shows. Also, having to close the hand douser between shows would make the use of start timers impossible.

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Ray Bernardi
Expert Film Handler

Posts: 120
From: Antrim, NH, USA
Registered: Feb 2003

posted 04-24-2003 08:07 AM

My gear is old to begin with, and there's nothing automatic about the dowser. My fear is that, being the knucklehead I am, I'll damage the equipment if I don't shut the damn thing off. I think it's okay for me, I run a pretty light schedule being a one screen small town operation. The only days we have more than one show are Saturday and Sunday. The time between shows just depends on how long the movie is.

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