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Topic: Christie bulb spacer question

Brad Allen
Jedi Master Film Handler

Posts: 688
From: Evansville, IN, USA
Registered: May 2000

posted 05-11-2005 06:38 PM

Monte, The SLH is the lamphouse (two piece) version of the SLC console according to Christies web site.

Yeah, me too, how many CFM's would be considered an overkill exhaust system?

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Mark Gulbrandsen
Resident Trollmaster

Posts: 16657
From: Music City
Registered: Jun 99

posted 05-11-2005 07:53 PM

Brad,
For one 2 to 3kw lamphouse I spec in a Grainger blower # 7C038, direct drive blower. I've been using these for years. you can buy the motors and blower seperate! but the pisser is that in the last year Grainger has discontinued their ball bearing motor that fit that unit. Now all thats available is the standard sleeve bearing motor and they need to be oiled twice a year. Emerson does make a ball bearing motor that will fit it but they are hard to find........ You will have less trouble with the ball bearing motors over the life of the blower unit.
7C038 Blower

With a 6" duct which is typical in a 2 to 3 kw lamphouse we typically shoot for the 765 cfm figure but in your area which is lower altitude the air movement will just be greater than it is out here. If your lamphouse is set for 8" duct then by all means use that! If you use these be sure to check the rotation of the thing after assembly..... they are always set to run backwards.... the rotation direction difference effects air movement by about 6 fold.

Check the local codes about installation! There are equivelent roof top "mushroom" blowers that have similar ratings and these are required in some areas.

Mark

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Bevan Wright
Expert Film Handler

Posts: 176
From: Fountain Valley, CA, USA
Registered: Sep 2003

posted 05-11-2005 10:44 PM

I've always been a believer in the 'Cat Test' rule for roof extraction. If you can suck a small cat up your roof exhaust it is about right. [Wink]

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Mark Gulbrandsen
Resident Trollmaster

Posts: 16657
From: Music City
Registered: Jun 99

posted 05-11-2005 11:41 PM

Yea Bevan..... that blower I posted above will then grind that cat into dog food [thumbsup]

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Brad Allen
Jedi Master Film Handler

Posts: 688
From: Evansville, IN, USA
Registered: May 2000

posted 05-12-2005 01:57 PM

So, I'm assuming that this blower would be suitable to use on my Ancient Kneisley Kni-tron Xenex Mod L2000's?

I remember now having experience elsewhere with this blower. What I have now is not even close to amount of air flow that blower provides.

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John Pytlak
Film God

Posts: 9987
From: Rochester, NY 14650-1922
Registered: Jan 2000

posted 05-12-2005 02:21 PM

Air flow meters:

Air Flow Meter

quote:
The CFM Master II provides simultaneous display of air velocity and temperature in an easy-to-read LCD screen. It provides minimum and maximum values and measurement of up to eight multi-point readings. The data hold function is ideal for transient readings, and the auto power off function conserves battery life.

Air velocity readings are displayed in any of the common scales in use: FPM, MPH, KPM, Knots, MPS and CFM. Temperature scale switches between °F and °C.

Other Meters

Contracting Guidelines

Measuring Air Movement

quote:
Measuring Air Movement (October 1999)
Providing the right amount of air to ensure occupant comfort requires a thorough knowledge of the instruments used to measure air volume and velocity in duct systems. It's information engineers should know.

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Gordon McLeod
Film God

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

posted 05-12-2005 11:04 PM

just rememebr it is possible to over cool a xenon lamp

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Fabrice Dubourg
Film Handler

Posts: 43
From: Granville, France
Registered: Feb 2003

posted 05-13-2005 04:12 PM

no,no, : do not over cool a lamp!!!! [Eek!]

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Dustin Mitchell
Phenomenal Film Handler

Posts: 1865
From: Mondovi, WI, USA
Registered: Mar 2000

posted 05-14-2005 10:19 AM

To answer your question (sort of question I guess) about who could look at your blower for you, if you are unwilling or unable to do it yourself your local HVAC service can look at it for you, that's who we have do maintenance on our rooftop exhaust systems.

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Louis Bornwasser
Film God

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

posted 05-14-2005 08:06 PM

We use the blower Mark suggests. In my experience it is not possible to overcool. (BTW hold onto the cleaning rag with both hands!)

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Brad Miller
Administrator

Posts: 17775
From: Plano, TX (36.2 miles NW of Rockwall)
Registered: May 99

posted 05-14-2005 08:37 PM

Agreed here with Louis, I have yet to find a situation where I can overcool a bulb. I've got 900CFM exhaust on a 2K lamp, but BOY OH BOY is it stable and lasts FOREVER!!! I wouldn't consider anything less than 900CFM on a 3k though as bare minimum. Best to hit 1200CFM for that and 1500CFM for a 4k, etc. [Cool]

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Gordon McLeod
Film God

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

posted 05-14-2005 08:48 PM

hmm 1500cfm through a 6" round duct
I think the linear air speed and static pressure would make that almost impossible

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Brad Miller
Administrator

Posts: 17775
From: Plano, TX (36.2 miles NW of Rockwall)
Registered: May 99

posted 05-15-2005 01:36 AM

SLCs have 8" openings, the duct is much larger to the roof, so it is pretty much maximizing the possible airflow.

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Gordon McLeod
Film God

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

posted 05-15-2005 09:57 AM

Based on a 8' diameter opening with a static pressure of 203" water for the use of a flexible duct connecting to the lamphouse to get 1500cfm of air the linear speed is 4299 feet per minute
hmm that would draw up a small dog not just a cat
One could have a 1500 cfm fan on the roof but with the effect of the flex and smallest opening I doubt it is actually drawing more than 750-800 cubic feet per minute through the lamphouse vent

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Steve Guttag
We forgot the crackers Gromit!!!

Posts: 12814
From: Annapolis, MD
Registered: Dec 1999

posted 05-15-2005 10:14 AM

Gordon,

I have measured in excess of 1200cfm on 8" ducts. However it is true that with smaller ducts it gets progressively much harder to attain higher cfm ratings. Typically the ducting system is 10" or larger than transitioning to 8" just above the projector with a flexible duct to allow for projector positioning. It is best to have a rigid duct attached directly to the lamphouse/console and a small section (3-feet or so) of flexible duct (I prefer insulated) to attached to rigid duct above the projector.

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