HSW installation under Ducts

[ABdesigner]

Hello forum members,

I have a question regarding correct installation of HSW sprinklers. Are sidewall sprinklers only allowed to be mounted on walls or bulkheads as per 8.7.4.1.2.2 (NFPA 13,2010). I am fairly new into Sprinkler design and wanted clear my thoughts regarding installation of HSWs. During my few site visits I have noticed HSWs being installed so often under ducts.

On this particular job, a Swimming pool area measuring 40' X 55' has 4 ducts 2 feet apart from one another creating obstruction to the sprinkler discharge. The on site crew had installed sidewall heads almost back to back on a 1" drop under one of those ducts. I see their idea to cover 14' X 14' with sidewalls on both the directions rather than installing (4) 1" drops under all 4 ducts and have upright heads. But my question is, Is this an acceptable installation per NFPA 13 ?

In my understanding of 8.7.4.1 , sidewall sprinklers shall be always mounted with deflector 4-6" off from a wall. But I am confused as sidewall sprinklers are used under the overhead doors as well.
I would really appreciate your comments and guidance.

Thanks.

 

[FPdesign101squared]

ABdesigner,
My concern with this application is the possibility of the sidewall sprinklers cold soldering. NFPA 13 2007 states 8.7.3.1.4 Sidewall sprinklers shall not be installed back-to-back without being separated by a continuous lintel or soffit. If This was my project, I would be using uprights!

Hope this helps!

 

[stookeyfpe]

That installation is a violation of NFPA 13 (2010 edition) Section 8.4.2. If it's in my jurisdiction it wouldn't be accepted. A duct does not equal a ceiling, based on Section 3.3.5.

 

[ABdesigner]

Stookeyfpe,

Thank you very much for your input sir. Being newbie, I was not confident enough to make such statement to a journeyman fitter who worked on this project and told me that he has been doing it this way pretty much throughout his career.
I really appreciate your response.

Thank you for your time sir.

FPdesign,

Thanks for you input as well, I was not sure if even a single sidewall was allowed to be installed in such way.