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Topic: exhaust requirements for followspots?

Scott Norwood
Film God

Posts: 8146
From: Boston, MA. USA (1774.21 miles northeast of Dallas)
Registered: Jun 99

posted 09-01-2002 12:22 PM

This isn't exactly "film" related, but hopefully someone can help.

What type of exhaust sytem (if any) is necessary for carbon-arc Super Trouper followspots when used indoors from a theatre balcony (i.e. not in an enclosed booth)? Do the require a special exhaust system like film projector lamphouses do, or is it safe to operate them for short periods (probably 10-15 minutes max. for pre-film introductory speeches, etc.) in a 900-seat theatre?

I've seen the arc Troupers used without ventilation in outdoor and large-venue (basketball arenas, etc.) environments without ventilation, but have only seen the xenon models used in theatre environments (also without ventilation).

One or two Super Troupers will (hopefully) be replacing a rather wimpy 1000w incandescent followspot in the near future....

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Ken Layton
Phenomenal Film Handler

Posts: 1452
From: Olympia, Wash. USA
Registered: Sep 1999

posted 09-01-2002 12:37 PM

I've only worked with carbon Troupers which are ac carbons and we never vented them. The Super Trouper uses DC carbons. All the places I ever saw Super Troupers in use never had ventilation for them.

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Dave Williams
Wet nipple scene

Posts: 1836
From: Salt Lake City, UT, USA
Registered: Jan 2000

posted 09-01-2002 12:47 PM

I have used one before without venting it. It was years ago in high school, but it was fine.

Dave

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Paul G. Thompson
The Weenie Man

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

posted 09-01-2002 01:08 PM

oops

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Paul G. Thompson
The Weenie Man

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

posted 09-01-2002 01:10 PM

Scott, I about 7 years ago at Sho-West, they were using them without venting. However, they had scrubbers on them to catch the remnants of carbon smoke, ash, and other impurities from entering the air in the banquet rooms.

I am sure Pat will chime in and give us the straight skinny on them....

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Gordon McLeod
Film God

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

posted 09-01-2002 01:11 PM

I think you will find that OSHA has something to say about this
Exhaust gasses from all forms of carbon arcs are dangerous and require venting.
The few place left using them I know of have a flexible fireproof cloth type spiral duct connecting them to a small exhaust to maintain a slight upward draft (small enough not to disturb the arc)

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Steve Kraus
Film God

Posts: 4094
From: Chicago, IL, USA
Registered: May 2000

posted 09-01-2002 02:21 PM

I've seen them atop the nosebleed seating area of a large arena where there was no connected exhaust but there appeared to be an air intake (presumably an exhaust to outside) in the ceiling close above each spotlight position.

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Paul Mayer
Oh get out of it Melvin, before it pulls you under!

Posts: 3836
From: Albuquerque, NM
Registered: Feb 2000

posted 09-01-2002 02:30 PM

For years (1968 - ca.1980) at the Las Vegas Hilton we ran carbon short-throw Super Troupers and the occasional 35mm w/Magnarc from the balcony and box booms of the 2200-seat main showroom without real venting. I'm sure OSHA would have a

fit if we ran carbon like that now. All we did for venting was to secure a 4-5' section of hose to the lamphouse and drape it over the backside pointing down. The spots operated for 1-1/2 to 2 hours per show, 14 shows a week with no complaints from the audience seated around us (of course in those days smoking was allowed in all showrooms here--which pretty much masked any carbon soot or odor problems). Obviously we had regular maintenance calls to clean the hose and carpet.

So, can you get away with running carbon like that for the occasional 10-15 minute stint?
More than likely.

Is it safe? By today's overly-protective standards, probably not. You may want to rig about 8' of hose such that it drapes over the back side of the lamp down to the floor and terminate it in a box with a damper, filter, and blower in it. Don't know the cfm needed for those lamps but it isn't much.

BTW congratulations on obtaining those spots. When properly maintained and operated they put out a beautiful light. I'm surprised one can still get carbons for them. Spare parts will be a problem though--here in the Neon National Forest the local Strong parts dealer gave away all their carbon-arc spare parts years ago.

As always, have fun!

Paul

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Scott Norwood
Film God

Posts: 8146
From: Boston, MA. USA (1774.21 miles northeast of Dallas)
Registered: Jun 99

posted 09-01-2002 03:19 PM

We have several boxes of 6mm negative and 7mm positive carbons left over from when this theatre was burning carbon for film projection (if I remember correctly, this is what the Super Troupers use, too, although we'll need to cut down the length), which hopefully should last for a while.

Does anyone bother to use carbon-savers in follow spots, or is it considered too risky when the exact burning time is not known?

Thanks for all the suggestions given so far and please keep them coming.

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Jeff Stricker
Master Film Handler

Posts: 481
From: Calumet, Mi USA
Registered: Nov 1999

posted 09-01-2002 07:39 PM

No venting for them at the Indiana State Fair Colisuem or the Dayton Hara Arena.

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Gordon Bachlund
Jedi Master Film Handler

Posts: 696
From: Monrovia, CA, USA
Registered: Aug 1999

posted 09-01-2002 08:11 PM

IMHO the short times you are planning to use your follow spots should not prove problematic.

In these days of environmental paranoia I am finding that the old adage, "It's better to ask forgiveness than to ask permission," serves well. I recall in the "old days" we never vented the follow spots since they were used occasionally and were of significantly lower wattage than the projector lamphouses which were used nearly continuously.

I've never heard of using carbon savers in follow spots.

Should you run low on carbons, I can help you.

Good luck.

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Paul Mayer
Oh get out of it Melvin, before it pulls you under!

Posts: 3836
From: Albuquerque, NM
Registered: Feb 2000

posted 09-01-2002 08:29 PM

IIRC 6x9 for the negatives and 7x12 or 7x14 for the positives. If your positive jaws have the stop pin in them you'll have to use 7x12 or shorter, or break off the last couple of inches of 7x14s.

Never saw anyone here use carbon savers in those lamps. Since it only takes a few seconds to shut down and "stretch" the carbons, no one bothered with savers. In a live show one can always find a moment to go out and stretch. You should be able to get around 1+20 to 1+30 burning time on a fresh trim. For 10-15 minute burns you'll easily be able to burn stubs.

Paul

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Randy Stankey
Film God

Posts: 6539
From: Erie, Pennsylvania
Registered: Jun 99

posted 09-01-2002 10:11 PM

We use Super Troupers in our theatre from time to time. Mostly xenons, though. I do remember them having carbons on one occasion. They weren't vented directly but they were in a flow spot booth that has a ventilation duct in the ceiling. Never had any problems.

I agree with the majority. Running them for 10-15 minutes at a crack shouldn't be a problem, assuming the room has enough ventilation.

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William Hooper
Phenomenal Film Handler

Posts: 1879
From: Mobile, AL USA
Registered: Jun 99

posted 09-02-2002 12:22 AM

Kicking some unwanted roommates out of the projection booth, Scott?

I've only seen them just vented to the room.
I think it would be best to get something to scrub them with, though.
Trapping the ash really shouldn't be much of a problem, it's pretty big. You could bend some sheet metal & build a little filter box with some cut to fit window AC filter foam sheets & a muffin fan.

What bothers me is C + O2 -> CO2
Even when they were just dumped to the projection booth, the booths still had lots of exhaust for the room.

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Gordon McLeod
Film God

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

posted 09-02-2002 09:55 AM

CO2 isn't as much of the problem as the rare earths in the ash and the nitous oxides being given off and Ozone
Most carbon arcs tend to produces CO and O3 because of the ultraviolet light

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