The reason that FM uses building height, not storage height is that
clearance (from top of storage to sprinklers) can have as much impact as
storage height on protection requirements. As clearance increases in a
building of a given height, the effectiveness of sprinklers decreases.
For any given building height, there is a worst-case combination of
storage height and clearance, and it's not the maximum storage height
the building will allow. 20 ft. of rack storage is easier to protect
under a 25 ft. roof than under a 35 ft. roof.
The best example I can give is that in the original ESFR testing, 35 ft.
storage of plastics in a 40 ft. building coulded be protected by K14
ESFRs at 50 psi, but 25 ft. storage under the same 40 ft. roof required
75 psi.
Joe
ndy Johnston wrote:
You might check 3.9.2 13,2002
Our FM wont allow us to define storage HT only the building can.
He said to often if the room is there they will use it.
Andy Johnston
-----Original Message-----
From: [EMAIL PROTECTED]
[mailto:[EMAIL PROTECTED] On Behalf Of Travis Mack
Sent: Monday, April 09, 2007 1:53 PM
To: [email protected]
Subject: RE: Roof Deck
Thanks everyone! The storage is going to be held to 20'. For Class III
multi-row racks <= 16', I can make it work as it stands.
-----Original Message-----
From: [EMAIL PROTECTED]
[mailto:[EMAIL PROTECTED] On Behalf Of Joe Hankins
Sent: Monday, April 09, 2007 11:30 AM
To: [email protected]
Subject: Re: Roof Deck
You can't use the bottom of the tee as the roof height any more than you can
use the bottom of a beam. In fact, the 22 in. deep tees create a much worse
situation than a metal deck on joists and beams. If a fire starts anywhere
other than under the channel where sprinklers are, operation will be
significantly delayed.
Joe
Travis Mack wrote:
Ok..this may be a stupid question, but here goes:
If I have concrete tee construction, what can I use as the roof deck. I
have an area with 28' to bottom of deck and 26'-2" to bottom of tee. If I
can use the bottom of tee as the maximum ceiling height, then I can use
0.60
gpm density using Tyco k17-231 sprinklers. If I need to use 28', then the
density goes to 0.80 gpm / sq ft. This is a retrofit, and the existing
system works with 0.60, but does not work with 0.80. I am looking for
something to justify the 0.60 gpm as being adequate.
Travis Mack, SET
MFP Design, LLC
480-505-9271
[EMAIL PROTECTED]
Examine yourselves to see if your faith is genuine. Test yourselves. Surely
you know that Jesus Christ is among you; if not, you have failed the test
of
genuine faith. 2 Corinthians 13:5 NLT
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