I have an interpretation from NFPA that states the 12-6 is ok. Looking for it 
now. The next edition of 409 is supposed to adopt the language from 13 
regarding this issue from what I was told.

Greg McGahan

Living Water Fire Protection
 (850) 937.1850 | Fax (850) 937.1852 | CellĀ (850) 554.3231


-----Original Message-----
From: [email protected] 
[mailto:[email protected]] On Behalf Of 
[email protected]
Sent: Thursday, February 25, 2010 1:56 PM
To: [email protected]
Subject: RE: Aircraft Hangar Question of the Day!

409-6.2.2.3 specifically states 12 ft. maximum on branch lines or between 
branch lines.  This in the general section not the foam section.  Under the 
closed-head water sprinkler criteria it refers back to 6.2.2.3.  So how could 
you just stick NFPA 13 criteria in here when the Standard is pretty clear?

For foam systems it's 100 sq. ft. max. but 12 ft is still the magic number.

Craig L. Prahl, CET   
Fire Protection Specialist
Mechanical Department
CH2MHILL
Lockwood Greene
1500 International Drive
PO Box 491, Spartanburg, SC  29304-0491
Direct - 864.599.4102
Fax - 864.599.8439
[email protected]
http://www.ch2m.com 


-----Original Message-----
From: [email protected] 
[mailto:[email protected]] On Behalf Of Thom McMahon
Sent: Thursday, February 25, 2010 2:41 PM
To: [email protected]
Subject: RE: Aircraft Hangar Question of the Day!

6.2.4 Closed-Head Water Sprinkler Systems for Aircraft Storage and Servicing 
Areas.
6.2.4.1" Sprinkler systems shall be either wet pipe or preaction, designed and 
installed in accordance with the applicable sections of NFPA 13 and the 
provisions of this chapter.

If 13 allows it for wet systems, so does 409 as stated above, so since 13 
allows the 12'6" in 25' bays so does 409.

I believe your reading the 12' max spacing from the foam or deluge sections, 
not the closed head water sprinkler system section.

Thom McMahon, SET
Firetech, Inc.
2560 Copper Ridge Dr
P.O. Box 882136
Steamboat Springs, CO 80488
Tel:  970-879-7952
Fax: 970-879-7926



-----Original Message-----
From: [email protected]
[mailto:[email protected]] On Behalf Of Ray Vance
Sent: Thursday, February 25, 2010 12:22 PM
To: [email protected]
Subject: Aircraft Hangar Question of the Day!

To my esteemed colleagues:

I have an aircraft hangar I am looking at and would like clarification on 
sprinkler / branchline spacing. I know what I think ;-) However, I would like 
the combined knowledge of all of you as to the actual requirements of the NFPA 
standards.

The hangar is a 32,000 suare feet Group-I hanger with a door opening to 
accomodate a 36 ft tail height.
The chosen fire protection scheme is Option-3, a closed-head wet-pipe sprinkler 
system at .17 gpm / 15,000 square feet and a low-level hi-ex foam system.
The building is a metal-purlin building with 25 ft bay spacing.

NFPA-409 requires a maximum 130 sf sprinkler spacing with a maximum distance of 
12 feet between the sprinklers or the branch-lines.
NFPA-409 does not reference NFPA-13 for sprinkler or branch-line spacing.

Question:

In a building with 25 ft bays would one be allowed to space the branch-lines at 
12'-6" as indicated in NFPA-13 for storage bays at 25 feet spacing in lieu of 
the 12 feet as indicated in NFPA-409?

Thanks,

Ray Vance - SET
Chief Sales Designer
Wayne Automatic Fire Sprinklers, Inc.
www.waynefire.com<http://www.waynefire.com>
407-877-5563   office
321-436-2184   mobile

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