GREAT SCOTT!! i mean, great, scott.
i have to admit i cringed a bit at 5' spacing-- SIX is The Minimum!
but that's when max deflector distance is also in play :)
you have inspired me to post a test question (test because i already
know the answer-- the job went out a couple years ago)
Quoting "å... ...." <eurekaig...@gmail.com>:
Very good points Bill and Wayne:
2007 NFPA 13: Chapter 17.3
I bet with 98% confidence that NFPA 13 intended the maximum horizontal
spacing of in-rack sprinklers for plastic storage in open, double- and
multiple-row racking at heights >= 25 ft to be
a). 10 ft for double pallet bays (for lack of a better name), and
b). 5 ft for single pallet load bays.
The true intention is eagerly sought, regardless of winning a bet or not.
The 10 ft horizontal maximum spacing "bet" is based on Note to Figure
17.3.1.2 and Note in Figures 17.3.1.4.3(a-d).
The 5 ft horizontal maximum spacing "bet" is based on Figure 17.3.4.1.4.
Coincidence as to the 10:5 ft maximum horizontal in-rack sprinkler spacing
relative to the 2:1 pallet loading/bay?
I think one item that bears repeating, is the intention to put an in-rack
sprinkler *in the transverse flue, *not simply comply with the maximum
horizontal spacing of in-rack sprinkler, wherever that spacing lands within
the bay.
Now, if I were the AHJ, and any contractor of honesty presented me with
rack columns having a 10' 4" transverse flue spacing, and the sprinkler
designer wanted to go with the "install in-rack sprinklers every-2-pallets"
horizontal spacing strategy... I would *strongly* consider giving a
variance of 4-inches on this maximum 10 ft iin-rack horizontal spacing.
Was I present at all or even more than a handful of UL or FM in-rack
full-scale fire tests, to fully know the implications of this variance?
No. But are many of the results from these tests presented as monograph
or video literature publicly available, and the essential findings from
these same tests, distilled as text into Annex A and B comments? Sure they
are. Have I reviewed them? You can bet that I have. Are there some
compensatory
mitigations that I as the AHJ might ask of our stakeholders, were I the AHJ
stakeholder to grant such a variance to the team? Sure, there are. If
those mitigations decreased sprinkler activation time, or increased water
delivery density, then those would be good mitigations, in that order.
Exercise of "good judgment" is the lubrication that keeps the customer
coming back for more...to borrow a mixed metaphor from that Conservative
party leader across the pond who -- two days on, at the Hague -- may "give
us more."
Most young professionals strive to learn the rules; many older
professionals struggle to remember the exceptions. Consideration of both,
rather than dogmatic overconfidence and/or blind allegiance to just one
ideology, is often more than enough to put a wind at our back as we go down
the path of delivering good decisions.
scot deal
Excelsior Fire/Risk Engineering
On Tue, Jan 15, 2013 at 11:09 PM, Bill Brooks
<bill.bro...@brooksfpe.com>wrote:
In my case the rack uprights were 10' 4" but with only two pallet loads. It
caused the addition of an extra sprinkler even after much writing and
attempted explaining of the rack uprights being the transverse flue. I
don't think this was the intent but it sure is written this way. It's an
unusual looking in-rack arrangement.
Bill Brooks
William N. Brooks, P.E.
Brooks Fire Protection Engineering Inc.
372 Wilett Drive
Severna Park, MD 21146-1904
410-544-3620
410-544-3032 FAX
412-400-6528 Cell
-----Original Message-----
From: sprinklerforum-boun...@firesprinkler.org
[mailto:sprinklerforum-boun...@firesprinkler.org] On Behalf Of å... ....
Sent: Tuesday, January 15, 2013 1:38 PM
To: SprinklerFORUM@firesprinkler.org
Subject: Maximum in-rack sprinkler spacing - plastic over 25ft
Wayne:
You make a good point.
Per NFPA 13 in-rack sprinkler layouts, I don't perceive that a gap between
pallets constitutes a formal transverse flue. I think the transverse flue
is
formed by the steel column of the racking structure.
Wayne, you are correct in that 2007 NPFA 13 Figure 17.3.1.2(a) includes the
exception-to-the-rule of having in-rack sprinklers in each transverse flue
(TF) for plastic storage in open racks two-or-more-bays deep, [1] that
stores commodities at heights 25+ ft.. NFPA 13 however, mitigates the
reduction of in-rack sprinklers (particularly, but not exclusively) at
every
transverse flue. For the case of Figure 17.3.1.2(a), this mitigation calls
for horizontal barriers above each level of in-rack sprinkler *with
face-sprinklers*. Does our situation you are describing contain such
horizontal barriers in the racking scheme?
One *could* assume (at least I do) that the horizontal spacing between in
rack sprinklers in Figure 17.3.1.2(a) is not to exceed 10 ft, as this is
maximum width of two pallets mentioned in Note 7 of this Figure. This
maximum horizontal spacing between in-rack sprinklers is enforced even if
metal racking support columns are spaced greater than 10 ft apart.
[1] new criteria added to this comment.
scot deal
Excelsior Fire
On Tue, Jan 15, 2013 at 4:03 PM, Dewayn
e Martinez <deway...@dbfp.net> wrote:
> Thanks Scot,
> What is confusing is that you are allowed to have more loads in the
> vertical as long as you don't go past 10ft spacing but nothing is
> mentioned for the horizontal spacing.
>
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