Film-Tech Forum ARCHIVE: Xenon: Leave It On...Or Turn It Off?

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Posted by Manny Knowles (Member # 1171) on 04-27-2002, 06:38 PM:

I know that some projector systems are designed to keep the Xenon "warm" to save them from the "perils" of ignition.

But leaving them on full-bore doesn't seem like it would be the greatest idea in EVERY case.

For those who haven't read the first few posts...over in the "Misuse" thread...

I complained that a new projectionist had left a Xenon burning without rolling film. (Forget the fact that she was totally unaware that she had ignited the lamp by accident.)

Jan added that she left hers burning all the time...but she also added that she's running 10 shows a day.

I'm talking about a theatre that has three shows a day...and we were about 4 hours away from showtime when I noticed the lamp burning.

How does one decide when to leave xenons burning and when to extinguish them between shows?

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And, hey! Let's be careful out there.

~Manny.

Posted by Paul G. Thompson (Member # 655) on 04-27-2002, 07:00 PM:

This has been discussed at length in another tread. It has its pro's and con's.

Personally, I don't leave them on between shows. Runs the power bills up too high. That's the "Con". I discovered there was no real savings in the long run. It almost balances out.

There is also a possibility that if you leave them on and the operator forgets that the movie is over and does not close the hand douser, the flimsy shutter in some of today's machines could become warped or burned. I don't think anyone wants to blast a flimsy shutter with a 2.5kw or higher lamp, or any lamp for that matter.....

Posted by John T. Hendrickson, Jr (Member # 849) on 04-27-2002, 07:29 PM:

Leave it on in a multiplex and you are simply asking for trouble. Too many screens, shows ending at different times. Sooner or later there will be a big mistake that will result in a changeover plate or a lens being cooked. Is that worth the savings in bulb life or electricity? Don't think so.

Posted by Michael Rourke (Member # 1142) on 04-27-2002, 08:42 PM:

Whatever money was saved on bulbs would go right into the A/C bill, trying to cool a room with 7 xenons running for 16 hours.

I would think you would be risking heat damage to the print if the bulbs were left on continually, even with the little dowser plate or lamphouse shield blocking the light/heat wouldn't there be the matter of heat via conduction? I have trap cooled 3K's and the traps still get pretty hot while running because my ventilation is getting steadily worse. In fact, when the freon went out on the booth A/C we had a little heat damage to a print.

If you were to leave bulbs on all the time then you'd better have really good ventilation, trap coolers, and keep the booth really cold.

John made a good point, what if your dowser cue doesn't work and the lens gets wrecked because your operator was on the phone or dropping the kids off at the pool?

Posted by Richard Hamilton (Member # 321) on 04-27-2002, 09:05 PM:

AC in a booth? HAHAHAHAHAHHAHHA thats a good one...

Posted by Dave Williams (Member # 299) on 04-28-2002, 12:48 AM:

You can apply the same logic to your household lighting. Do you leave it on when you leave the house for work? For vacation? For a movie? Probably not. Sure you might save a light bulb by not exposing it to multiple ignitions, but the cost of the electricity bill would far outweight the cost of the bulbs in no time flat.

Take a look at how many amps these zenons run. Calculate that into cost of leaving it on all the time all day versus the cost of POSSIBLY shortening its life by starting it an extra four or five times a day. It just doesnt add up, and besides you wont actually know if you are saving the bulb or not until you wear it out or burn it out. In my experience, I have had bulbs last four weeks and I have had bulbs last 18 months. So it really is up to so many variables, that there would be no need to leave them on all damn day because you MIGHT save a few hours on the bulb, at the cost of astronomical light bills and possible equipment damage.

My advice, turn it off!!!

Dave

Posted by Steve Kraus (Member # 476) on 04-28-2002, 09:19 AM:

Running changeovers, I leave both on for the duration of the show and between screenings if a lamp will be used within 45 min to an hour otherwise I shut it off. This has gotten me high mileage on the bulbs but at a platter theatre I wouldn't see any reason to alter the normal practice of letting it run for the duration of the show only. One start per two hours or so of use is not so bad.

Posted by Jan Hackett (Member # 1231) on 04-28-2002, 09:34 AM:

10 shows a day....large format.....45 minutes per show. 15 minute intermissions. So I am not running 20 hours a day. My venue is a bit different. 7kw bulb. Only one projector. I have seen booths maintained both ways but my theory is think about when a lightbulb in your house ussually burns out...it burns out when you turn it on. The same discussion happens in computer circles with PC techs. Not about bulbs but computers. BTW I leave my computer on 24-7.

------------------
Jan Hackett
Theater Operations Manager
Extreme Screen Dynatheater
NM Museum of Natural History Foundation

Posted by Gordon McLeod (Member # 33) on 04-28-2002, 10:17 AM:

Almost all large format theatres leave the lamp lit all day.
Bulb life is greatly extended and usually with far less flicker and other abnormalities.
Current consumption and HVAC issues are really not a pricy issue in the longterm. But it does require that the dowser be closed when the machine is not running. Strong and others offer a motorized dowser option

Posted by Dave Williams (Member # 299) on 04-28-2002, 11:59 AM:

I should have said that my experience is with platter machines.

On the issue of leaving computers on 24/7, there is much discussion on this. If you do leave it on 24/7, you run a risk of total failure if you suffer a power outage. The reason is that with this practice the contacts on the board will expand so far that during a long power outage, the contraction of the contacts can cause a MB failure, which can also lead to other failures such as HD failure etc. If you leave it on 24/7, make sure you have a battery backup, as most power failures are short term.

Just a thought.

Dave

Posted by Manny Knowles (Member # 1171) on 04-28-2002, 11:59 AM:

Jan - I wondered how you managed to have so many shows...large format never occurred to me.

I agree with you...I don't think I've ever seen a household bulb expire while it's already turned on. Always when it's just turned on. So, I see your point.

But I think I'm going to go with shutting them down between shows...longer intermissions here.

BTW, I leave my computers on 24-7 too. I reboot once in a while out of superstition, though.

...and, yes, I have them all on UPS battery backups that offer about 10mins of power.

------------------
And, hey! Let's be careful out there.

~Manny.

Posted by Will Kutler (Member # 770) on 04-29-2002, 08:14 PM:

To leave it on, or leave it off....that is the question, ha ha!

I do think that it depends on your particular booth and equipment.
In a change-over booth, leave em on, but let them shut off after a show with a multi-plex/platter operation.

Here are some scenarios you may cover:

Think of your lense probles should your change over fail! Also, the bulb heat can cause change-over blades to warp such as the Christie. But Christie has attempted to solve this problem.

I have also seen some small independant houses where the lamphouses were in delipated condition and the lamp house dousers did not do much good! I have also seen some independant houses running platters without any kind of changeover or failsafe assembly!

If you do opt to keep lamps lit, is your "projection" staff intelligent enough to properly look after them?

I guess that the bottom line is that bulb wear can be reduced by keeping them lit for at least 1/2 hr before shut down...that frequent striking will lead to excessive wear, and this is covered in many bulb and lamphouse manuals! But keeping them lit for extra time will also wear them down.

I guess it is just common sense for your particular theater...

Posted by Gordon McLeod (Member # 33) on 04-29-2002, 09:00 PM:

Will your post didn't seem to make a lot of sense since it is advocated leaving them lit only if you can safely and properly do so and that is been continously mentioned.
Bottom line if you have the properly trained staff and equipment to do it you will relise lower operational osts if the lamps are left lit and since most places that can do so already do lets leave it at that

Posted by Richard Hamilton (Member # 321) on 04-29-2002, 09:01 PM:

The large format booths that I've been in "usually" have a full time projectionist with no other screens to watch, and are for the most part either experienced or trained in that booth and know how important the presentation is. Not to mention the cost of a replacement film, lens, shutter, etc.... unless the intermission is over an hour long, I instruct them to leave the lamp on.

Rick

Posted by Dave Macaulay (Member # 813) on 04-29-2002, 10:30 PM:

"AC in a booth? HAHAHAHAHAHHAHHA thats a good one..."

In our local AMC multis the booth is the return air duct... so they get second-hand air conditioning at least.There are filters where the auditorium air comes into the duct/booth but it's a constant battle to keep the equipment (and that plastic strip stuff rolled up on the platters) clean.

Posted by Mark Gulbrandsen (Member # 72) on 04-29-2002, 11:42 PM:

Hey Pat More,
This is a perfect place to post Jack Schmidt's list of reasons for leaving lamps lit a certain length of time(one hour min. I think). If you could get that list and post it here alot could be learned...or better yet get hime to register here and post it.
The best reason had something to do with the amount of shock a lamps quartz envelope gets when its been on for 15 or more min, turned off and then re-lit after just a few minuites(This is common in Spotlights). The amount of pressure on the envelope is unbelievable at this time as the Xenon gas is still very high in pressure, and any lamp(even new)is at its peak of possibly exploding at this point.
If you can get it, or if he could post this here it would be appreciated by all of us.
Mark @ GTS

Posted by Darryl Spicer (Member # 711) on 04-29-2002, 11:51 PM:

That is something that I have noticed when attending concerts that fifteen minutes before the first act hits the stage those spots are powered up and stay on until the end of the main acts performance.

Posted by Paul Mayer (Member # 355) on 04-30-2002, 12:49 AM:

As has already been stated, it depends on the situation. What I've seen over the years for different applications is:

For spotlights: Strike up early enough so that if there are problems, one has time to troubleshoot and replace stuff (15-20 minutes seems about nominal). Stay lit until the end of the show and shut down between shows. In 'Vegas we always seem to have at least an hour between shows. If the break is less than 30 minutes, leave 'em lit. Observe a few minutes cooling time with fans running after shutdown.

For IMAX: Same as above for strike up. Leave lit for the day, running at idle current between shows (assumes approx 40 minute shows with 20 minute breaks inbetween). Lamp cools after end of day shutdown and is cool enough by the time the print is rewound and covered, logs are done, field flattener cleaned, and the film path blown and brushed out.

For changeovers: Strike both and leave both lit for the show if running on 2k reels. If running 6k reels, killing the other lamp may be an option. I prefer to leave them both running though.

For platters: Again I like to strike early enough to have time to deal with any problems--which requires use of the hand dowser. Obviously this doesn't work for timer or remote starts unless one can automate the hand dowser. Whether to stay lit or not at the end depends on how long the break is--if it's less than 30 minutes, I like to leave 'em lit and use the hand dowser. Of course I return control of the lamp to the failsafe if I'm not going to be at the machine--a little CYA for unexpected stops or if I miss the end. Again a few minutes of cooling with fans at the end, during which time I wipe stuff down, do the logs and cover the print.

As always, just my 0.02USD.

Posted by Manny Knowles (Member # 1171) on 04-30-2002, 01:30 AM:

I'm curious if there is a maximum length of time you can leave xenons lit?

Typical day at one of these cinemas is three shows weekdays, 5 shows on Saturdays and during peak holiday periods.

Lamp types in use are...

XM1600HS
XM1600H/VC
XM2000H/VC
XM2000HTP

------------------
And, hey! Let's be careful out there.

~Manny.

Posted by David Favel (Member # 1125) on 04-30-2002, 01:42 AM:

The most I ever ran a xenon was from 1.00p.m. Saturday till 8.00a.m. Sunday for our marathon.

Today I installed a 2500 H/S lamp.
I was fine tuning with my left hand on the focus & looking thru the port at the picture when it exploded.

After 6 hours I can now hear in my left ear though my trousers are still a bit sticky.