Film-Tech Forum ARCHIVE: Christie Lamphouse Ventilation Question

This is topic Christie Lamphouse Ventilation Question in forum Film Handlers' Forum at Film-Tech Forum ARCHIVE.

To visit this topic, use this URL:
https://ft-forum.com/ft/cgi-bin/ubb/ultimatebb.cgi?ubb=get_topic;f=1;t=008213

Posted by Gary Crawford (Member # 2038) on 08-22-2006, 12:14 PM:

Christie Xenolite K30 lamphouses, late 1960s vintage. Looking to replace the old roof-mounted squirrel cage exhaust blower, used back in the days of arc lamps, with in-line fans like you have in forced-air heating systems.

I have the manuals from the Christies but nowhere does it list a recommended CFM / air flow requirement. Do any of you folks have this info?

Thanks!

Posted by Dustin Mitchell (Member # 372) on 08-22-2006, 12:44 PM:

The amount of airflow required will depend on the size of your lamp. I've heard on this site the rule of thumb 'if it can suck the Sunday paper up the stack then you have enough airflow.'

Posted by Monte L Fullmer (Member # 2797) on 08-22-2006, 12:44 PM:

Definitely -

Good luck - Monte

Posted by Gary Crawford (Member # 2038) on 08-22-2006, 12:53 PM:

If by size you mean wattage...2000. If you mean the size of the lamphouse...oh, I'd say...about a cubit-and-three-quarters long, a cubit wide and a cubit tall, give or take...

I've seen some posts in here that claim improper CFM can make the lamp run too hot, or too cool, and the bulb life will suffer, etc etc etc, so was just wondering if anyone had some historic Christie ventilation info that might be important.

Don't think the Sunday paper will fit into the lamphouse, and if it did fit, the heat of the bulb would set in on fire, and all the soot and ashes from the newsprint, and the charred wiring in the lamp, and the theater owner whining and crying...

Posted by Louis Bornwasser (Member # 3063) on 08-22-2006, 02:13 PM:

Minimum of 500 cfm at the stack, with doors closed and all stack back pressure accounted for.

1000 cfm is better.

I do not recommend in line blowers. The squirrel cage blower should be located above the projector on the underside of the roof. You are correct in removing roof-mounted units due to their expense and failure rate.

This has been covered fully within the last 90 days. Louis

Posted by Mark Gulbrandsen (Member # 72) on 08-22-2006, 02:27 PM:

I use a Dayton 985 cfm which is the smallest blower I will install and if you run 3kw or larger more like 1500 cfm. Measured with doors closed but dowser open!

Mark

Posted by Brad Miller (Member # 2) on 08-22-2006, 05:42 PM:

Agreed, I have yet to find an issue of "overcooling", and I can proudly report in excess of a YEAR's worth of grind house running on one 6K lamp with 1500CFM exhaust. (Christie lamphouses+Christie bulbs, of course)

The more the better. The opening on the top of your lamphouse will ultimately be the restrictive factor, so put in the biggest mother of a fan you can.

PS - your subject title sucks as badly as that little fan on top of your old console did. Please change it to reflect what we are really talking about. Christie makes more than this one product, ya know.

Posted by Gary Crawford (Member # 2038) on 08-23-2006, 12:49 PM:

Title fixed.

1000 CFM, better 1500, and in-line fans not recommended.

Thanks guys.

Posted by John Pytlak (Member # 331) on 08-25-2006, 10:44 AM:

Although you want to be sure that the lamphouse blower has sufficient airflow to properly cool the lamp, Osram cautions against overcooling a lamp, or cooling it unevenly, as it creates turbulance inside the lamp, leading to an unstable arc plasma:

http://ecom.mysylvania.com/miniapps/FileNet2/EngineeringBulletins/ENGR_BLTN11.pdf

quote:
See page 25 about "Excessive Cooling"

Posted by Louis Bornwasser (Member # 3063) on 08-25-2006, 04:30 PM:

I, too, have heard that from Osram. I have NEVER found it to be true in actual use. (TWO Sunday newspapers worth is about right...hold on to your cleaning rag!!) Louis

Posted by Gordon McLeod (Member # 33) on 08-25-2006, 04:35 PM:

Actually I have had occasion of over cooled lamps several times that cause premature unstability