This is topic Lamphouse w/o exhaust in forum Film Handlers' Forum at Film-Tech Forum ARCHIVE.


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Posted by Dominic Espinosa (Member # 2122) on 08-15-2007, 10:25 AM:
 
I wonder if you guys can give me confirmation on this...
It's my understanding that due to statutes regarding the radiation put off by the lamps a xenon lamphouse has to be vented to the outside, correct?

And in order to ensure proper cooling, the lamphouse (such as an LP with a 3k lamp) should have it's blower pulling in air from the booth and it's exhaust pulling air out of the lamp house, no?

I noticed one of my locations is doing exactly the oposite. We're blowing hot (~90F weather) air into the lamp house instead of exhausting.
Thoughts?
 

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Posted by Gordon McLeod (Member # 33) on 08-15-2007, 10:35 AM:
 
In some locations codes require that the lamphouse be vented to the outside
Normally the internal blower of the lamphouse should draw in cool room air and the vent pipe on the top should be connected to a blower to provide sufficient suction to maintain a negative pressure inside the lamphouse
 

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Posted by Ken McFall (Member # 845) on 08-15-2007, 03:02 PM:
 
I so wish there were some tighter guidelines here in the UK.

I look after a small four screen that had lamphouses which were not ducted and you could look in and see the xenon lamp when it was running!! This was more of a concern as the projectors, vic 5's, were at floor level so when standing you looked directly into the lamphouse vent. The lamp houses are 1600w vertical cinemeccanica. Needles to say I have changed this.

ALL lamphouses should be ducted and vented outside. Projection rooms get hot enought without all that extra heat to deal with.
 

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Posted by Rick Deleau (Member # 4212) on 08-15-2007, 03:31 PM:
 
Unrelated to this topic.

I would like to contact me in regards to buying up some equipment at

ps sorry for butting in.

Thanks Rick

Edit - I would like for Rick Deleau to read the rules page before he posts further. -Brad

[ 08-15-2007, 07:02 PM: Message edited by: Brad Miller ]
 

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Posted by John Pytlak (Member # 331) on 08-15-2007, 04:57 PM:
 
Because dangerous ozone may be formed by either the high voltage ignition or by the UV from the xenon lamp, lamps should be vented to the outside.
 

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Posted by Michael Moore (Member # 3867) on 08-15-2007, 05:46 PM:
 
Because of the Renovation to the building I'm in, we have no way to truly vent to the outside without making some major architectural changes, however I have been running now almost every Sunday and Wednesday night by venting to the air return of the booth form the AC. It is the only way vent it out. It's all I have been able to do, The AC Unit is right above the Lamp house, Also even after a long movie 2 hours or more the room never gets over 80F

Mike
 

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Posted by Scott Norwood (Member # 30) on 08-15-2007, 05:55 PM:
 
I've seen lamps up to 2kw vented into the booth (see photos of the Wellesley College cinema). It is also common for 16mm and video projectors (with xenon lamps from 350w to 2kw) to not have outside exhaust. It doesn't seem to cause any major issues, but it is probably a) not very good for bulb life and b) probably not a good idea for a venue that would run film every day.
 

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Posted by Mark Gulbrandsen (Member # 72) on 08-15-2007, 06:39 PM:
 
I have run 3kw exhaust into the room for portable work. Its only for the duration of one or two showings though.

Mark
 

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Posted by Dominic Espinosa (Member # 2122) on 08-15-2007, 06:55 PM:
 
Hey, Mr. P! Long time no see, probably since I've been running around all this time. Good to see you though.

The question I really have is this: if I have NO outside exhaust BUT I'm blowing hot, dirty air, from the outside of the building am I reducing the life of the lamp?
 

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Posted by John Hawkinson (Member # 1135) on 08-15-2007, 10:31 PM:
 
So, the questions are: 1) is the bulb getting adequate cooling 2) is the contaminated air from outside causing a problem?

For (1), what it really comes down to is how much air is moving over the envelope of the bulb. Lamphouses are generally designed to pull air past the bulb envelope, and I wouldn't think reversing the direction of the exhaust fan would have that effect. None of the measurements are easy to do; probably your best bet is to measure the temperature of the air coming out of the lamphouse, and perhaps of the lamphouse and projector itself. Also, how much airflow are you getting?

For (2), well, how dirty is your air? If you don't get particles of crap that touch the bulb or reflector and stick to it, then it's probably fine. And I'd be surprised if your air was that dirty.

You should be able to answer some of this empirically -- how much life are you getting out of these bulbs? All 3 of the intake fan on the lamphouse, the exhaust fan on the lamphouse, and the main exhaust fan are all running backwards? How did it end up this way?

Modern bulbs are "Ozone-free" (OFR), meaning that, once struck, their glass filters out the ionizing radiation that makes ozone. So theoretically you only get ozone at ignition time, when the wavelength of light is different. So it probably not a major issue to have OFR lamps exhausing into the booth, but it is certainly not the right way to engineer the system.

--jhawk
 

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Posted by Bryan M. Montgomery (Member # 4412) on 08-16-2007, 12:46 AM:
 
If you have no lamphouse ventilation, the forced air system will be rendered nearly useless after a while, which in my experience leads to excessive heat build-up and premature seal failure on the bulbs. Venting to the air return ducting may work as long as your HVAC is running. I've had roof fans fail many,many times and have come up with an excelent emergency fan that I place between the lamphouse and the flexible ducting we have. Be creative and come up with a solution.
 

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Posted by Jeremy Weigel (Member # 4208) on 08-16-2007, 09:51 AM:
 

quote: Dominic Espinosa

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I noticed one of my locations is doing exactly the oposite. We're blowing hot (~90F weather) air into the lamp house instead of exhausting.

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quote: Louis Bornwasser

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I once found 12 of 16 exhaust blowers wired to run backwards, even though the HVAC guy "inspected" each one monthly for .....17 years. Even single phase fans will run backwards if wired that way. "Universal" motors require the installer to check the direction. The problem is that the HVAC guy installs and the electrician wires. There is no power when the HVAC guy works.

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quote: Michael Moore

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Ozone has not been shown to be a carcinogen; however it has been shown to act synergistically with gamma rays in – vitro to be a co-carcinogen. But only after the cells were damaged by the gamma rays, there was no indication of cancer with cells pretreated with ozone. I would be much more concerned with the powerful oxidative state that ozone is in. Ozone is a powerful oxidizing agent and It reacts with organic compounds to produce ozonides, which are unstable and may decompose with explosive violence. Ozone is an unstable gas which, at normal temperatures, decomposes to diatomic oxygen very rapidly, so as soon as the ozone is made It decomposes just as fast. Now if one were to bottle it up in a room with no ventilation at a rapid rate then there might be an issue if a bottle of acetone or either is open.

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Now lets not be too paranoid about running a simple Xenon lamp .

Unless you get a very old xenon lamp that is not ozone free you are not going to have any problems from ozone. Having had portable systems for dailies (2X 2kw lamps) set up in small usually 10X10 "boxes" all over the place for many years with no ozone or ill effects were ever noticed.

I think Michaels posted refrence would be considered more towards workers that re-fuel or work with nuclear reactors since there are both ozone and gamma rays emitted by a reactor weather its running or not.

When the first large scale nuclear reactor was brought on line at Hanford it shut itself down after about 12 hours of running because of the poisioning effects of Xenon Gas that built up inside the reactor. Another 12 hours later and it came back up all by itself because of Xenon Gas 's short half life. The reactor had to be loaded with more fuel than was thought necessary to overcome that poisioning effect.

Mark
 

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Posted by Dave Macaulay (Member # 813) on 08-20-2007, 11:57 AM:
 
Don't worry about the xenon disapeearing from your lamps.
Xenon has 7 stable isotopes and 6 known radioactive ones. The lamps use a stable isotope, hopefully! Xe135 is the one that poisons reactors. This isotope absorbs neutrons nicely and has a half-life of about 9 hours, decaying (through beta emission) to Cesium 135 which has a half-life of a few million years.
 

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Posted by Michael Moore (Member # 3867) on 08-20-2007, 05:03 PM:
 
Mark
True, it has been showed many times now that ozone by itself has no known carcinogenic effects but it does have effects if cells are compromised due to radiation.

Also it is important to know that if Ozone was a carcinogen then why is it that Welders, particularly welders who use TIG (heli-arc) do not have much higher rates of cancer then any other welder and they are breathing larger quantities of Ozone.
 

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Posted by Gordon McLeod (Member # 33) on 08-20-2007, 06:55 PM:
 
In modern systems the majority of the ozone is emitted during ignition and I can remember working in several cramped multiplex unvented booths were after all the shows started the smell of ozone lingered for 10 -15 min.
 

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Posted by Frank Angel (Member # 248) on 08-21-2007, 01:56 AM:
 
But back to the air flow around Dominic's lamp and how hot the projector gate is getting -- seems the easiest thing would be to try to reverse the air flow out of the lamphouse stack (instead of having it flow in -- very counter intuitive, but may possibly been done not by accident but by someone's design for a reason lost in antiquity) and see if this reduces the heat issue. If that temp goes down significantly, make the motor reverse change permanent. If it gets worse, then go back to what you found.

What I can't understand is, since proper airflow and air cooling is so essential to the life of the lamp as well as to its structural integrity, and since knowing if the airflow is doing what it's supposed to be doing, why can't the manufacturers situate one or more heat sensors near the bulb with a readout on the panel so you could know definitively if the cooling system is actually cooling the bulb properly. That floppy air vane is a pretty crude and primitive indicator of what the cooling system is actually doing to the bulb -- all it can possibly tell you is if the fan is turning. Especially that some have pointed out elsewhere that you can put a fan in the stack thinking that it will enhance the internal fan, only to that that auxiliary fan's air-flow can in fact counteract the proper flow around the bulb and actually reduce the cooling action of the system or worse, cause the bulb to be cooled unevenly.

Thermometers are not all that new nor that expensive. Or if that is too high-tech for the manufactures, then how about simply indicating in the manual what the correct air temp should read at the stack or at some specific metal part of lamphouse body. This way an operator can check the lamphouse with his own thermometer and get a little more accuracy than just his touching with his fingers and having to take some wild guess whether it is hotter than "normal." At least tell him what normal is supposed to be. Or is that beyond the pale?
 

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Posted by Bastiaan Fleerkate (Member # 3826) on 08-21-2007, 05:03 AM:
 
So... is it a bad idea to vent the warmth of the lamps trough ducts that end into the foyer to save money on the heating bill?
 

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