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» Film-Tech Forum   » Operations   » Film Handlers' Forum   » How to best increase the exhaust stack diameter?

   
Author Topic: How to best increase the exhaust stack diameter?
Jeremy Weigel
Phenomenal Film Handler

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


 - posted 12-21-2008 07:08 PM      Profile for Jeremy Weigel   Email Jeremy Weigel   Send New Private Message       Edit/Delete Post 
What would be the best way to increase the 6" diameter exhaust to an 8" diameter on our Super Highlight consoles?

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Monte L Fullmer
Film God

Posts: 8353
From: Nampa, Idaho, USA
Registered: Nov 2004


 - posted 12-21-2008 07:22 PM      Profile for Monte L Fullmer   Email Monte L Fullmer   Send New Private Message       Edit/Delete Post 
You can get a 8" to 6" reducer that would mount on top of the console exhaust opening..then hook up the 8inch stack to this reducer.

 -

How this 8" flex exhaust is hooked up to this X-90 console using this reducer.

-Monte

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Jeremy Weigel
Phenomenal Film Handler

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


 - posted 12-21-2008 08:41 PM      Profile for Jeremy Weigel   Email Jeremy Weigel   Send New Private Message       Edit/Delete Post 
That's what we have now. I'm just looking to make it a straight 8" all the way to maximize air flow.

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Monte L Fullmer
Film God

Posts: 8353
From: Nampa, Idaho, USA
Registered: Nov 2004


 - posted 12-21-2008 10:04 PM      Profile for Monte L Fullmer   Email Monte L Fullmer   Send New Private Message       Edit/Delete Post 
Actually doing the reducer does increase air flow since the smaller diameter is actually making the air move faster - like blowing out air with your mouth open against blowing with lips partically closed - air moves faster through smaller openings.

If you're after an increase of volume of air, then you need to incease your fan's CFM up on the roof almost double if you want to open to an 8 inch at the top of the console to keep the same air speed.

If you have exhaust problems, remedy the problems on the roof and not down at the intake.

You could put a booster fan in the booth above the console in the stack to enhance air flow if your draft going up the stack is weak..

-Monte

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Mark Gulbrandsen
Resident Trollmaster

Posts: 16269
From: Bountiful, Utah
Registered: Jun 99


 - posted 12-22-2008 08:03 AM      Profile for Mark Gulbrandsen   Email Mark Gulbrandsen   Send New Private Message       Edit/Delete Post 
Heck ... Wrong International ALWAYS puts too small of flange on their consoles! If you want 8 " all the way down then remove the 6" flange open up the hole and install an 8" flange... That should go obvious though. Also be sure your air flow is at least 750 vfm up to 2kw lamps and at least 1200 for 3kw and up. Also be sure your blower is turning in the correct direction and if you're at high altitude you will have to have a larger blower than normal!!!
Mark

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Monte L Fullmer
Film God

Posts: 8353
From: Nampa, Idaho, USA
Registered: Nov 2004


 - posted 12-22-2008 01:10 PM      Profile for Monte L Fullmer   Email Monte L Fullmer   Send New Private Message       Edit/Delete Post 
quote: Mark Gulbrandsen
Wrong International
..what have they done RIGHT? .. [Big Grin]

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Bruce McGee
Phenomenal Film Handler

Posts: 1776
From: Asheville, NC USA... Nowhere in Particular.
Registered: Aug 1999


 - posted 12-22-2008 05:58 PM      Profile for Bruce McGee   Email Bruce McGee   Send New Private Message       Edit/Delete Post 
Jeremy,

Is there a problem with you current draft? Have you checked out the blower itself for a clogged fan?

I have 7 fans on the roof. I cleaned all of them just last week before it got so COLD here in western NC. All of them were filthy and clogged.

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Gordon McLeod
Film God

Posts: 9470
From: Toronto Ontario Canada
Registered: Jun 99


 - posted 12-22-2008 07:33 PM      Profile for Gordon McLeod   Email Gordon McLeod   Send New Private Message       Edit/Delete Post 
You know Strong has done many things right The Super Lumex and the X60 for starters
cleaning up the casting issues with the XL
They maintain parts for discontinued product
So give them a break
If you don't like there equipment don't sell it or don't service it and if you work at a theatre with it go somewhere else as that is what the owner chose
Strong has been good to the industry not perfect they have had lots of oopps but this phrase "wrong international" just doesn't fit them

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Mark Gulbrandsen
Resident Trollmaster

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From: Bountiful, Utah
Registered: Jun 99


 - posted 12-22-2008 09:06 PM      Profile for Mark Gulbrandsen   Email Mark Gulbrandsen   Send New Private Message       Edit/Delete Post 
quote: Gordon McLeod
They maintain parts for discontinued product

Ha! Thats a big laugh. In fact thats one of their worst aspects. Try getting parts for a 70mm JJ trap sometime or Ballantyne gate or trap parts... they're non-existant. Prices are through the roof on the things that are left... as much as 400%! Of course there is LaVezzi and Wolk to help keep that under control. Try finding someone that actually knows a thing or two about their automations of the past...
And another thing Gordo... The Super Lum-Ex and X-60 were not designed by Strong International... those were inherited designs done by wise people and built by wise people back when Strong was in Toledo. I will give them credit for the better X-L castings and the switching power supplies though... I make a gob of money repairing the latter.

Sorry, but only a thing or two right still keeps em Wrong for most of us here on this forum.

Mark

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Gordon McLeod
Film God

Posts: 9470
From: Toronto Ontario Canada
Registered: Jun 99


 - posted 12-22-2008 10:18 PM      Profile for Gordon McLeod   Email Gordon McLeod   Send New Private Message       Edit/Delete Post 
funny I just got delivery of a lot of ballantyne pro 35 parts last week

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Jeremy Weigel
Phenomenal Film Handler

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


 - posted 12-23-2008 01:04 AM      Profile for Jeremy Weigel   Email Jeremy Weigel   Send New Private Message       Edit/Delete Post 
quote: Mark Gulbrandsen
If you want 8 " all the way down then remove the 6" flange open up the hole and install an 8" flange...
Ya nailed it Mark, but what is the best way to enlarge the hole?

quote: Bruce McGee
Jeremy,

Is there a problem with you current draft? Have you checked out the blower itself for a clogged fan?

I have 7 fans on the roof. I cleaned all of them just last week before it got so COLD here in western NC. All of them were filthy and clogged.

No problems per se. All the blower fins are fairly clean considering they are right at 20 years in service and have never been cleaned or serviced. Hell they even still have the original motors! [Eek!]

It was just after reading many posts about getting the CFM up near the 700-800 range for 2K's to help maximize lamp life, that it would be a good start to have an 8" diameter all the way instead of having a bottle neck in the system with the reducer.

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Monte L Fullmer
Film God

Posts: 8353
From: Nampa, Idaho, USA
Registered: Nov 2004


 - posted 12-23-2008 02:02 AM      Profile for Monte L Fullmer   Email Monte L Fullmer   Send New Private Message       Edit/Delete Post 
quote: Jeremy Weigel
getting the CFM up near the 700-800 range for 2K's to help maximize lamp life
...but, that's using stock 6" exhaust. You're gonna need to dbl that CFM draw out of the ceiling if you're changing to a full 8" exhaust.

You're missing the boat with this reducer thing: Try this trick then - take a newspaper with and hold it against the 6" opening with your EXH fan on. That paper should be well stick to the entrance of the stack. Now, disconnect the 8" from the reducer and do the same trick and I bet the newspaper will not hold to the 8" exhaust since the vacuum is much less since you reduce the vacuum by adding more volume of air.

..same as a garden hose: how much water pressure do you have compared to a 5/8"x 25ft hose to a 1 inch hose of the same length when the water comes out of the end? You've added volume of water since more water per sq.feet comes out, but the pressure is reduced at the same water per sq.feet.

With that pict setup that I added above, I'm getting 1400CFM's going up that stack .. with a single turbine roof fan! For what this 8plex has is a unique single EXH fan setup: All the machines have the reducer to 8 inch flex with each flex heading into 12 inch round duct. Then the 12 inch heads into a 18inch round plenun, which in turns heads into them main 10x14 plenun where the fan is mounted on.

In the main plenum, the vacuum isn't really all that much-maybe 1 inch of vacuum. Yet, with the stepped lines, the vacuum increases at each step by a decent margin to where the 8inch flex is almost drawing 700CFM, and at the mouth of the 6inch on the console, the CFM's almost triple to 1500CFM's.

6 consoles are running the 2k bulbs and I can avg 4 to 6k hours on Christie CXL-20r bulbs. the other two houses - one running a Christie 30SC and the other one running a Christie 25SC .. and both consoles aren't even warm to the touch (course I cheated a bit here: took out the muffin fan that rests below the anode and put in a small squirrel cage fan to have more direct air flow to keep the anode seals cooler with these bigger bulbs..and it works wonders-since the consoles are empty where the amp rack is separate from the console due to THX requirements in these two houses)...and they have the reducers on the stack on this exhaust system.

..just trying to help.... - Monte

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Steve Guttag
We forgot the crackers Gromit!!!

Posts: 12295
From: Annapolis, MD
Registered: Dec 1999


 - posted 12-23-2008 06:07 AM      Profile for Steve Guttag   Email Steve Guttag   Send New Private Message       Edit/Delete Post 
Oh Pepermint Pattie....er Monte...you are quite mistaken on your theroies of air flow...

CFM or cubic feet per minute measures VOLUME...you are mistaking that with lineal air speed, or how fast the air is moving by a point.

To use your water hose analogy...take your hose and fill a bucket and time how long it takes to fill the bucket....now take the same hose and bucket and use your thumb to put a restriction in the water exiting the hose to increase the water pressure exiting the hose and fill the same bucket....I can guarantee you it will take longer to fill the bucket with water even though it will be going into the bucket more violently due to your restriction.....why? The VOLUME of water has been reduced. If you think about it...a faucet would be a very scary thing if when you closed it off...the water volume INCREASED up until the point it stopped!

Each restriction reduces air flow...NEVER increases it. While yes the speed has been increased for what air is allowed to remain flowing (at the point of restriction), the total amount of air flowing is less.

I wonder how many people here actually own (and use, or know how to use) an anemometer. 700-800cfm on a 6" stack is very hard to obtain and will whistle horribly and, depending on the construction of the system, try to collapse. Even 500-700cfm on a 6" stack will whistle pretty well and you'll often hear the duct work pop once the air is removed.

In terms of heat...at around 1000-1200cfm...even a 7KW lamphouse should feel cool to the touch or maybe just a tad warm. Most every lamphouse I've encountered, with 1500cfm (or more) will start to have issues with the air currents inside...dousers, heat filters...you name it will start to rattle, flap and even air vains will false trip as the swirling air currents occasionally cause a revrse flow around the switch. Just because you start with a 2000cfm or more fan doesn't mean you'll get that at the other end of the duct...each restriction comes off of that.

Steve

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Mark Gulbrandsen
Resident Trollmaster

Posts: 16269
From: Bountiful, Utah
Registered: Jun 99


 - posted 12-23-2008 08:22 AM      Profile for Mark Gulbrandsen   Email Mark Gulbrandsen   Send New Private Message       Edit/Delete Post 
Jeremy,
Basically remove the existing one and cut an 8" hole with a sabre saw as cleanly as you can. 8" flanges can be had from many sources... possibly even Home Depot. Place a drop cloth inside the unit to catch any filings that will drop down and run a vaccum cleaner whilst cutting the hole. Have some assistance to do the job.

Steve is absolutely correct on every point he makes. The anamometer I reccomend is the type that only requires a small 1/8" hole be drilled in the pipe... its the only type that will give you a true reading on airflow because it allow the door to be closed while taking the reading. The propellor type are just really meaning less and will only give you a basic idea of how much airflow you have as you have to have the door open to get the reading.

Mark

P.S. Gord, We have been retiring Ballantynes in this neck of the woods. They have seen better days... and it's just one of many reasons that Strong discintinued the product in the first place. Please come down and fill your pickup with them and haul them back to Canada!

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Louis Bornwasser
Film God

Posts: 4435
From: prospect ky usa
Registered: Mar 2005


 - posted 12-23-2008 10:17 AM      Profile for Louis Bornwasser   Author's Homepage   Email Louis Bornwasser   Send New Private Message       Edit/Delete Post 
Give me a big enough fan and I'll pull the 1000 cfm through a McDonalds straw! (I'm only kidding a little bit!)

We have a surface mount circuit board oven here that has 2-3" exhausts with a 7.5Hp motor. It came that way, was designed that way and, with a bit of effort, it works.

I would not cut the lamp. I would run 8" as far as possible, and live with the small 6" restriction at the lamp. 30 years experience says it's not worth butchering the lamp. Perhaps you need a redesigned pipe or a larger blower? Louis

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