But Larry, if the beams are not an obstruction to heat flow OR spray
pattern, it's like they don't exist, no?
Brad.
Quoting Larry Keeping <[email protected]>:
You don't need to do anything special with the deflector distance.
As per 8.5.2.1.1 (2), the line spacing is to a wall or obstruction:
(2) Between branch lines as follows:
(a) Determine perpendicular distance to the sprinkler on the
adjacent branch line (or to a wall or obstruction in the case of the
last branch line) on each side of the branch line on which the
subject sprinkler is positioned
(b) Choose the larger of either twice the distance to the wall or
obstruction or the distance to the next sprinkler
(c) Define dimension as L
The is no argument that the beams that delineate the bays are
obstructions. Even if the spray can throw under it, that doesn't
change that consideration.
Larry Keeping
-----Original Message-----
From: Sprinklerforum
[mailto:[email protected]] On Behalf Of
[email protected]
Sent: December-21-17 5:53 PM
To: [email protected]
Subject: Re: S & L Rule
I recently learned that the beam only acts like a wall if you can't
throw under it, so get those deflectors way up there!
(Crow and Thunderbird rocks)
Merry Christmas Forum,
Brad.
Quoting Bob <[email protected]>:
The beam is an obstruction that acts like a wall. You’re covering
floor space, so as long as each sprinkler covers the correct area (30
sf), then the spacing that you are describing sounds in compliance
with NFPA 13 spacing rules.
Thank you,
Bob Knight, CET III
208-318-3057
From: Sprinklerforum
[mailto:[email protected]]
On Behalf Of James Crawford
Sent: Thursday, December 21, 2017 3:00 PM
To: [email protected]
Subject: S & L Rule
We have been having a discussion in the office about the S&L rule for
spacing of sprinkler heads. We received a sprinkler drawing with some
spacing that we do not agree with, see below, but can find no specific
direction in NFPA #13 (2013) that says it is wrong.
Basic situation we have a small building with a 20’ bay and a 30’ bay.
Ordinary hazard spacing.
For the 20’ wide bay, we have2 lines spaced at 10’ apart , so we have 5’
off the wall then 10’ between the next line and 5’ to the beam line,
the heads are spaced at 13’ along these lines.
Then we have a 30’ bay where we have 2 lines spaced 15’ apart, 7’6
off the beam then 15’ between the heads then 7’6 to the wall, heads
are spaced at 8’
along the line
So our discussion is the sprinkler lines along the beam line which
would be 5’-0” plus 7’-6” for 12’-6” between the line. The
sprinkler heads in the 20’
bay are spaced at 13’-0”, so if we use the S&L rule these heads are
spaced at 12’-6” x 13’-0” or 162.6 ft². Is this correct?
And yes I know we could space the 30’ bay with 3 lines at 10’ apart
and that is what I would do but it is not our design.
Comments
Thank you
James Crawford
Phaser Fire Protection Ltd.
Phone 604-888-0318
Fax 604-888-4732
Cel 604-790-0938
Email [email protected]
Web www.phaserfire.ca
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