If you need to protect above the duct and get quicker detection then you
could use vertical sidewall heads on candle sticks up the side of duct and
stagger space.

Russell Gregory 

Christchurch New Zealand


From: Sprinklerforum [mailto:sprinklerforum-boun...@lists.firesprinkler.org]
On Behalf Of Larry Keeping
Sent: Thursday, 15 September 2016 3:32 PM
To: sprinklerforum@lists.firesprinkler.org
Subject: RE: Noncombustible concealed space


I would offer two points for your consideration:


1.      There was an old formal interpretation that advised that deletion of
sprinklers above a duct was a question for the AHJ, who could access all of
the circumstances.

2.      Sprinklers above open grid ceilings need to be in compliance with
Section 8.15.14.


Larry Keeping


From: Sprinklerforum [mailto:sprinklerforum-boun...@lists.firesprinkler.org]
On Behalf Of Tim Stone
Sent: September-14-16 10:04 PM
To: sprinklerforum@lists.firesprinkler.org
Subject: Noncombustible concealed space


I have an interesting situation. 


Steel and concrete School building. A Corridor runs down the middle on each
floor about 8' wide, W12 steel I-Beams forming the side at the floor deck
above, (About 12'-0 Floor to Bottom of deck).

There is a large duct running the length of the Corridor about 7'-6 wide x
24" tall. This leaves a gap of about 3" on each side between duct and
sheetrock partitions. The top of the duct is about 11" below the steel
Q-Deck above.

An open metal grid ceiling system is installed 12" - 16" below the duct. 


We are installing upright heads 1"-4" below the duct allowing the water to
spray down through the open grid ceiling.


The question is, do I need to install heads above the duct? There will be no
way to service or replace these heads and if installed between the duct and
the wall, the head will not meet the minimum 4" off the wall.

Referencing 2010 ed., concealed spaces, I believe I am following
the intent.


Thank you in advance.



G. Tim Stone


G. Tim Stone Consulting, LLC

NICET Level III Engineering Technician

Fire Protection Sprinkler Design

and Consulting Services


                117 Old Stage Rd. - Essex Jct., VT. 05452

CELL: (802) 373-0638   TEL: (802) 434-2968   Fax: (802) 434-4343



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