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Topic: Lamphouse w/o exhaust

Dave Macaulay
Film God

Posts: 2321
From: Toronto, Canada
Registered: Apr 2001

posted 08-17-2007 09:10 PM

It is completely wrong to blow outside air into the lamphouse. Either someone misunderstood the specifications and did it on purpose, or the blower is either installed backwards accidentally or miswired to run in reverse.
Many types of exhaust fans will blow backwards if the motor rotation is reversed. Checking this is always on my list for new installs... with 3 phase blowers it is very easy to have a reversed fan, and even single phase blower motors are occasionally - fairly often actually - wired up for the wrong direction.

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Dominic Espinosa
Phenomenal Film Handler

Posts: 1172
From: California, U.S.A.
Registered: Jan 2004

posted 08-18-2007 10:16 AM

As I understand the booth is how we inherited it many many moons ago so it's possible (I doubt a motor would last this long ~20 years) that it was pre-existing.

After being run this way for so long wouldn't I run the risk of damaging brushes and or bearings by reversing it since it's all worn in the other direction already?

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Jeremy Weigel
Phenomenal Film Handler

Posts: 1062
From: Edmond, OK, USA
Registered: Mar 2007

posted 08-18-2007 10:40 PM

It could be that someone maybe replaced the motor and put the blower wheel on the motor shaft in the wrong direction. Unless there is a directional switch (like a ceiling fan) I doubt reversing the wiring will have any effect since it is more than likely running on 120v AC.

[ 08-19-2007, 12:34 AM: Message edited by: Jeremy Weigel ]

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Louis Bornwasser
Film God

Posts: 4441
From: prospect ky usa
Registered: Mar 2005

posted 08-19-2007 06:39 AM

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.

Inside the connection lid usually there are instructions on which 2 wires to reverse. No harm was done, since there are no brushes in an AC motor and bearings don't care. (If a 3 phase motor, reverse any 2 of the 3 wires.)

The reason this has to go "outside" is that ozone is cancer-causing. If you store it in an attic or outside, it will rapidly become oxygen and then be harmless. Louis

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Mark Gulbrandsen
Resident Trollmaster

Posts: 16657
From: Music City
Registered: Jun 99

posted 08-19-2007 09:45 AM

quote: Louis Bornwasser
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.

That was a very common problem around my service paths for a while. They are all going the correct direction now! Add to this problem the fact that many Dayton blowers can have the blower wheel inserted into either side of the cage and this further adds to the problems. This is also the equivelent of having the blower run backwards.... thay HAVE TO be assembled with the vanes in the right direction on the correct side of the housing! Reversing the motor with the blower wheel inserted in the wrong side of the cage won't fix the problem...

Mark

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Michael Moore
Expert Film Handler

Posts: 188
From: Dover, DE / USA
Registered: Jun 2006

posted 08-19-2007 07:40 PM

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.
Mike

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Gordon McLeod
Film God

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

posted 08-19-2007 08:04 PM

OSHA requirements for ozone exposure
http://www.osha.gov/pls/oshaweb/owadisp.show_document?p_id=21606&p_table=INTERPRETATIONS

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Mark Gulbrandsen
Resident Trollmaster

Posts: 16657
From: Music City
Registered: Jun 99

posted 08-20-2007 10:08 AM

quote: Michael Moore
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.

Now lets not be too paranoid about running a simple Xenon lamp [Roll Eyes]

.

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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Dave Macaulay
Film God

Posts: 2321
From: Toronto, Canada
Registered: Apr 2001

posted 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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Michael Moore
Expert Film Handler

Posts: 188
From: Dover, DE / USA
Registered: Jun 2006

posted 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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Gordon McLeod
Film God

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

posted 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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Frank Angel
Film God

Posts: 5305
From: Brooklyn NY USA
Registered: Dec 1999

posted 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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Bastiaan Fleerkate
Film Handler

Posts: 85
From: Linschoten, Utrecht, The Netherlands
Registered: Jun 2006

posted 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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