You might be interested in some of the new provisions in NFPA 13-2016 that
relate to this subject:
Types of sprinklers below obstructions:
8.5.5.3.3 Sprinklers installed under obstructions shall be of the
same type (spray, CMSA, ESFR, residential) as installed at the ceiling
except as permitted by 8.5.5.3.3.1.
8.5.5.3.3.1 Spray sprinklers shall be permitted to be utilized under
overhead doors.
Sprinklers below round ducts:
8.6.5.3.7 Sprinklers installed under round ducts shall be of the
intermediate level/rack storage type or otherwise shielded from the
discharge of overhead sprinklers.
Obstructions to ESFR Sprinklers:
8.12.5.3.3* For pipes, conduits, or groups of pipes and conduit to be
considered individual, they must be separated from the closest adjacent
pipe, conduit, cable tray, etc. by a minimum of three times the width of the
obstruction.
A.8.12.5.3.3 ... Otherwise the pipes and/or conduits would be
considered as a group when applying the obstruction criteria of 8.12.5.3.1
Light Hazard Protection with ESFR Sprinklers:
12.6.7.1 ESFR sprinklers designed to meet any criteria in Chapter 12
or Chapter 14 through Chapter 20 shall be permitted to protect any of
the following:
(1) Light hazard occupancies
(2) Ordinary hazard occupancies
(3) Any storage arrangement in Chapter 13 referencing OH1, OH2, EH1,
and EH2 design criteria
Larry Keeping
-----Original Message-----
From: Sprinklerforum [mailto:[email protected]] On
Behalf Of Gregg Fontes
Sent: September-03-15 11:32 AM
To: [email protected]
Subject: RE: Larger circular duct obstructions
Ken,
So you would installed the ESFR sprinkler directly under the center point of
the round duct. (i.e. the 84" diameter duct, the sprinkler would be at 42"
from the edge at the listed distance below.) Would a round duct collect enough
head to set this off???
Thanks,
Gregg Fontes
Cen-Cal Fire Systems, Inc.
209-334-9119
-----Original Message-----
From: Sprinklerforum [mailto:[email protected]] On
Behalf Of Parsley Consulting
Sent: Thursday, September 03, 2015 6:46 AM
To: [email protected]
Subject: Re: Larger circular duct obstructions
Greg,
A couple of thoughts come to mind for me.
First, I would regard the large circular duct as similar to unobstructed
construction. The location of the deflector of the sprinklers below the duct
would have to be as called out in 8.12.4.1.
So, for those purposes the position below the duct would be driven by the
k-factor you're using.
Second, the use of an ESFR system to protect LH/OH occupancies is allowed
by 12.6.7.1, provided that the original design was per the criteria in chapters
12 through 20. I don't think the manufacturers are going to stand behind
designing ESFR's to meet obstruction rules for standard spray sprinklers. To my
way of thinking the continuous obstruction rules of 8.12.5.3.1 would still be
applicable. I don't agree that it would be possible to eliminate the concern
over obstructions less than 48" wide, as items (3) and (4) of that section
suggest 24" is the cutoff width.
I don't know if that's correct, however those are my initial thoughts.
*Ken Wagoner, SET
*Parsley Consulting***
*350 West 9th Avenue, Suite 206
*Escondido, California 92025
*****Phone 760-745-6181*
Visit our website <http://www.parsleyconsulting.com/>
***
On 09/02/2015 2:18 PM, Gregg Fontes wrote:
> Looking at a building that has ESFR fire sprinkler protection. Half
> is being used as open office area. They are installing circular ducts
> from 32" to 84" diameter with the top of the duct approximately 36"
> below the ESFR deflector (right below the roof trusses). In reading
> 8.12.5.3 2013 edition, in most cases if not all, Table 8.12.5.1.1
> cannot be met, so sprinklers will need to be installed under the
> ducts. With the duct being 32" to 84" diameter, where would the fire
> sprinkler be placed? Per NFPA 13 is a flat barrier required to be
> installed under the circular duct? FM give you a guideline, but 13
> does not. Owner does not want the ESFR sprinklers change out, so
> again where would you place the sprinkler and/or is a flat barrier
> required by NFPA 13? (With a flat obstruction you can either be under
> it or within so many inches of the end, but a huge diameter
> obstruction, is it the edge, center ,etc.?)
>
> Second thought, since this is no longer a storage application, can you
> apply the standard spray sprinkler obstruction rules? (This still
> does not state where to install the sprinkler below the obstruction,
> but you could eliminate the obstruction less than 48".)
>
> Thanks,
> Gregg Fontes
> Cen-Cal Fire Systems, Inc.
> 209-334-9119
>
> _______________________________________________
> Sprinklerforum mailing list
> [email protected]
> http://lists.firesprinkler.org/listinfo.cgi/sprinklerforum-firesprinkl
> er.org
>
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