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» Film-Tech Forum   » Operations   » Film Handlers' Forum   » Stack Blowers (Page 1)

 
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Author Topic: Stack Blowers
Paul G. Thompson
The Weenie Man

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


 - posted 04-15-2002 01:09 AM      Profile for Paul G. Thompson   Email Paul G. Thompson   Send New Private Message       Edit/Delete Post 
To help with xenon bulb cooling in the Strong Super Lumex, I have inserted 5C964 325CFM duct blowers from Grainger in the exhaust run.

I also stuck some meat thermometers in the stack ductwork to monitor the air temperature. Without the blowers, the air temp was hovering around 130 degrees....Way too hot!

With the blowers installed, it brought it down to about 120 degrees....still too hot.

I throttled the xenon bulb current down from 95 amps to 85 amps, and the temperature dropped to about 100 degrees. Finally, I almost rest my arm on the front top of the lamphouse without saying, "Damn!"

I also sent one of the kids up in the attic to find out what in the devil is up there for stack blowers. They looked like toilet bowls to me.....He will provide me with the make and model of the blowers that are up there, and maybe I can finally find what the rating is. I'll bet they are about 200cfm's.....with an additional 10 feet of stack on the output end, which will derate them to about 175 or so.

Are the temperatures within parameters?

I hope so....I have nothing to compare it with....What do you think?

PS - I am running 2500-watt lamps. 85 amps at 26 volts = 2210 watts.


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Rick Long
Jedi Master Film Handler

Posts: 759
From: Toronto, Ontario, Canada
Registered: Nov 1999


 - posted 04-15-2002 01:15 AM      Profile for Rick Long   Email Rick Long   Send New Private Message       Edit/Delete Post 
Paul, what size bulb are you burning in this lamphouse? O.K., I didn't see the 2500-watt rating the first time i looked.


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Paul G. Thompson
The Weenie Man

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


 - posted 04-15-2002 01:23 AM      Profile for Paul G. Thompson   Email Paul G. Thompson   Send New Private Message       Edit/Delete Post 
Rick, you beat me to the edit. They are 2500 HS lamps.

The installer of the equipment outfitted the lamps with Q-Arc 3000's, and set them up to 100 amps. All of the Q-Arc lamps failed.

I am now burning LTI's in No. 1 and 2, and a Christie in No. 3. The Christie just went out of warrenty, but it is about shot. It was running too hot, and that is what ruined it.


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Rick Long
Jedi Master Film Handler

Posts: 759
From: Toronto, Ontario, Canada
Registered: Nov 1999


 - posted 04-15-2002 01:36 AM      Profile for Rick Long   Email Rick Long   Send New Private Message       Edit/Delete Post 
Paul, I know you already know this, but Strong calls for 300 cfm exhaust on this lamp. In addittion I remember a bulletin ( in the 80's) from Strong stating that this lamp was not designed to be used with a bulb higher than 2500-watt.

Couple of obvious questions again; is the incoming air system (the intake fan on the side of the lamphouse) operating properly? Is the ammeter lying to you?

I have a couple of situations with this lamp/bulb combination. I will take your ingenious idea of the meat thermometer along with a millivolt measurement across the lamphouse meter shunt and report them at my earliest opportunity.


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Paul G. Thompson
The Weenie Man

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


 - posted 04-15-2002 01:47 AM      Profile for Paul G. Thompson   Email Paul G. Thompson   Send New Private Message       Edit/Delete Post 
Thanks, Rick.

Yes, the intake blower is running properly, and it is the right ones in these lamphouses. I have thought the ammeter might be lying to me for quite some time, but I never checked it that closely. I think it is within at least 10%, though. I'll "clamp" it next week to see how far it is off. Since I only run that booth once a week, my time is limited and have to do one thing at a time.


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Wes Hughes
Expert Film Handler

Posts: 175
From: Raleigh, NC, USA
Registered: Aug 2001


 - posted 04-15-2002 04:56 PM      Profile for Wes Hughes   Email Wes Hughes   Send New Private Message       Edit/Delete Post 
120 degrees in the stack is TOO hot???!!!

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Paul G. Thompson
The Weenie Man

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


 - posted 04-15-2002 06:25 PM      Profile for Paul G. Thompson   Email Paul G. Thompson   Send New Private Message       Edit/Delete Post 
Yup!

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Paul G. Thompson
The Weenie Man

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


 - posted 04-20-2002 04:22 PM      Profile for Paul G. Thompson   Email Paul G. Thompson   Send New Private Message       Edit/Delete Post 
Bringing this back to the top.

OK, here is the scoop. I have inspected the duct work we are using with our Strong Super Lumex Lamps, and here is what we have.

Sitting on top the lamp house, I have a Grainger EF-8 325 CFM Booster fan. The output end of the fan is reduced to 6 inches, and proceeds up to the ceiling (about a 4-foot run to the ceiling.)

There are two 6 inch 90-degree elbows, one below the ceiling, and one above. Continuing up from the attic-side of the ceiling is another booster fan manufactured by Fan Tech, which is a Model No. FR-200 rated at 360 CFM. The output side of that unit is stacked out an additional 12 feet through the roof, with a diffuser/blast defector to keep the rain out of the ductwork. To my knowledge, all ductwork in the attic is 8 inch in diameter, but I can’t be absolutely sure since it is insulation rapped.

With 2500 watt xenon lamps running at 80 to 85 amps, my exhaust temperatures are running around 115 degrees F.

A question for the ductwork engineers……does this make sense? I still think the temps are too high. Seems to me that if I increase the size of the booster blower on the lamp house to the next Grainger size of 475 CFM, it would be fighting the booster fan in the attic.

Any comments, caustic or otherwise, would be greatly appreciated.

Thanks, guys.

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Rick Long
Jedi Master Film Handler

Posts: 759
From: Toronto, Ontario, Canada
Registered: Nov 1999


 - posted 04-20-2002 08:34 PM      Profile for Rick Long   Email Rick Long   Send New Private Message       Edit/Delete Post 
Paul, those right-angle bends have got to be costing you a lot of air-flow (I forget the percentage). Perhaps an inexpensive way around this is to replace it with flexible metal duct.

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Stephen Jones
Master Film Handler

Posts: 314
From: Geelong Victoria Australia
Registered: Jun 99


 - posted 04-20-2002 09:08 PM      Profile for Stephen Jones   Email Stephen Jones   Send New Private Message       Edit/Delete Post 
Is the exhaust fan unit operating ok with no faults etc,also are the blades clean with no build up of dirt dust etc as this will restrict the units exhaust capacity.Also check the ducting for any blockage etc.Is the exhaust unit single or 3 phase if its 3 you may also have lost a phase?
just my thoughts.
Steve

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Paul G. Thompson
The Weenie Man

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


 - posted 04-20-2002 09:58 PM      Profile for Paul G. Thompson   Email Paul G. Thompson   Send New Private Message       Edit/Delete Post 
Stephen, thank you for your thoughts. All our stack blowers are single phase. I installed the 325CFM boosters because the exhaust temp was well into the 130's. By hand feel, it felt comparable to a 200CFM suction in the stack.

This problem was from day one of this new theater. I want to make it clear I had nothing to do with it's design.

Rick: Yes, you are right. The 90-degree elbows are partially the cause of the problem. Each 90 degree elbow is equivalent to what one would lose in a 10 foot straight duct. That comes close to 20 CFM for both joints.

Unfortunately, there is not much I can do about eliminating the 90 degree elbows because the way they were built into the building's ceiling. The way the ductwork is designed, I am certain I am losing at least 40 to 50 CFM including the loss across the elbows. It is a guess, because I don't know how to calculate the loss exactly.

What is up in the attic looks like public outhouse fans that you would expect to see in a two-hole low usage outhouse. That's the best description I can give right now.

It sure gives me the impression that if I want to get good milage from the xenon bulbs, I am going to have to re-do the whole kit and cabootle as money becomes available.

Furthermore, I might have to check with the city to see if we can do it right. Our building is a peaked roof, and that's what the city wanted so I have been told. Now it becomes an issue to how much more junk we can put up on the roof to without compromising the city's beautification rules.



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Rick Long
Jedi Master Film Handler

Posts: 759
From: Toronto, Ontario, Canada
Registered: Nov 1999


 - posted 04-20-2002 11:48 PM      Profile for Rick Long   Email Rick Long   Send New Private Message       Edit/Delete Post 
What about going the other way round and mounting a stack fan on top of the lamphouse? Get rid of the blades in the old one.

Only problem I can think of that may happen is higher booth noise and possible vibration issues.

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Paul G. Thompson
The Weenie Man

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


 - posted 04-21-2002 12:31 AM      Profile for Paul G. Thompson   Email Paul G. Thompson   Send New Private Message       Edit/Delete Post 
Rick, that is a possibility. It is going to have to be a big one - the duct run is long because of the peak roof. Thanks

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Jerry Chase
Phenomenal Film Handler

Posts: 1068
From: Margate, FL, USA
Registered: Nov 2000


 - posted 04-21-2002 01:10 AM      Profile for Jerry Chase   Author's Homepage     Send New Private Message       Edit/Delete Post 
Drop ceiling or fire rated ceiling? Pipe is cheap. Can you replace the 6" with 8" and do a gentler angle from the top of the lamphouse to the connection above the ceiling? A diagram or photo could be helpful in seeing what is going on.


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Paul G. Thompson
The Weenie Man

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


 - posted 04-21-2002 02:21 AM      Profile for Paul G. Thompson   Email Paul G. Thompson   Send New Private Message       Edit/Delete Post 
Jerry, it is a fire-rated ceiling. 2 slabs of 5/8 sheetrock. Metal ductwork box through the ceiling, with at least 6 inches if insulation.

If I can obtain the plans for the building, I can draw a picture of it for posting. But for me to get up there and measure and see just exactly what it is really like, is physically impossible for me because age-related problems.

I had to send one of my kids up there just to find out what kind of blowers were up there. About as far as I could go safely because of my condition is to stick my head up through the ceiling hatch.

I am afraid my days of bouncing around in attics and climbing latters, snaking around things, and balancing on ceiling trusses are over.


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