For the one similar I was involved with it was further complicated by the
fact the dome rotated front to back in the theater to allow both 2d and 3d
movies. This was an omni theater, so similar but not the same. Depending
on the position of the semi-sphere at least 1/3 of the floor was obstructed.
The only solution that had any merit was installing a mist system in the
floor. Granted there was very little to support this approach but the
theory was wet what wasn't burning. Ultimately, this was abandoned for
cost.
We settled on a significantly increased remote area. Certainly 3000 sq.ft.
might have been 5000 sq.ft. and strict limits on what they could do in the
theater. If they used the front for any type of presentation the dome had to
be back and thus no obstruction. Each presentation had to be approved by
the fire marshal. Movies and the associated equipment were considered the
normal case. In the first 6 years they only showed movies. The only thing
to burn was the seats. Granted they had foam filling. But otherwise there
wasn't really anything else to burn.
In a static case I don't a problem with covering the floor under the dome
the best you can with a surround technique with large orifice heads and
extended coverage sidewalls, increase the remote area and limit combustibles
especially in the unprotected area. Certainly put heads above the screen.
Case experience - a 100' wide x 400' long hood over a paper drying process.
The original hood was wood. They installed a metal one over the top but
hadn't finished or removed the wood. No sprinklers under either hood. Fire
gets into the wood hood. Sprinklers in the over head operate (200+) but the
water runs off the metal. This is a 100 yo wood plant. Fire looks
spectacular but really doesn't go anyplace. Never even shut down the paper
line during the whole incident.
Yes there will be some area in the middle that will be unprotected. It's
not code nor really "engineered" with math and fancy formulas but short of
going through the screen or getting really expensive in the floor you are
stuck.
Chris Cahill, P.E.
Fire Protection Engineer
Sentry Fire Protection, Inc.
763-658-4483
763-658-4921 fax
Email: [EMAIL PROTECTED]
Mail: P.O. Box 69
Waverly, MN 55390
Location: 4439 Hwy 12 SW
Waverly, MN 55390
-----Original Message-----
From: [EMAIL PROTECTED]
[mailto:[EMAIL PROTECTED] On Behalf Of George Lau
Sent: Tuesday, September 09, 2008 9:25 PM
To: [email protected]
Subject: Help!! Sprinkler in Planetrium
Dear Sprinkler Experts,
I am new to the forum. Besides a "Hi" to yall, I am desperately seeking
suggestion or reference regarding the "Sprinkler installation in a
PLANETARIUM" which possesses a (60ft dia) semi-spherical dome screen (made
of white paint coated matellic plate with small holes). Our current plan is
to keep all those sprinker heads above the dome screen. Is it a workable
design?
Since we are lack of local technical reference, can anyone throw me some
light regarding the normal practice, if the sprinkler heads should be above
the dome screen. If yes, what other concerns/attention should be paid?
Thank you so much,
George Lau
Macau S.A.R.
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