Sprinklers Below Perforated Ceilings

[KLH]

Hello all,

I have a perforated, metal pan ceiling (50% free area)in an office building corridor that requires a wet-pipe, NFPA-13 sprinkler system. There is a thin acoustic pad laying on top of the ceiling. The ceiling and acoustic pad are clearly an obstruction for sprinklers located above the ceiling, so the sprinklers will be located below the ceiling. The construction above the ceiling is non-combustible.

Will the perforations in the ceiling allow the heat to escape into the interstitial space above the ceiling, failing to activate the sprinkler? Perhaps the acoustic pad is sufficient to keep the heat below the ceiling.

I cannot find anything in NFPA-13 addressing this issue.

I would like to get some of your opinions/experiences before I call the local authority.

Thanks in advance.
Ken

 

[cdafd]

Without seeing it hard to call

How wide of corridor?
How much/long corridor???


How thick is the pad???
Will it burn???

But with fifty per cent of ceiling open , yes that seems alot, and would question sprinkler head activation

Will check the book

 

[cdafd]

not sure if the defintion of unobstructed construction helps any

3.7.2 and look at the examples for open grid in A.3.7.2 nfpa 13 2010

a thought is if the ceiling has fifty per cent opening is it a ceiling, in that wil it collect enough heat to activate the heads, if not, than the arguement could be that the sprinkler heads are to far down from what would be the actual ceiling.


thought there use to be something in 13 about all drop in ceiling tile had to be in place?

and also allowances for light fixtures, duct work in ceilings?? as in openings?

 

[Sprinklerfitter]

Could this be classified as obstructed construction? What is the distance of the finished ceiling from the roof or deck? Perhaps the 22" rule would apply? If the distance would be too great from the deck, can the sprinklers be spaced for above and below while still maintaining minimum 6-0 between?

 

[rmae]

I would say no you cannot locate the sprinklers only below the 'perforated ceiling' as a 'thin acoustic pad' laying on top of the 'preforated ceiling' would never be considered as the same as a continuious ceiling that NFPA 13 considers to collect the heat to activate the sprinklers. And you certainly can't locate the sprinklers only above the 'perforated ceiling/ acoustic pad' tag team as you are deep into obstruction rules. Remove the pad and you might be into an open grid ceiling but it needs to be in accordance with 8.15.13 (2010). As described, I believe sprinklers will be required above and below the ceiling because the real ceiling would be the deck above and the lower 'perforated/pad' ceiling is a continuious obstruction that you need to provide sprinkler protection below.

R M Arsenault Engineering Inc.

http://www.rmae.ca

 

[cdafd]

Klh

Like this or bigger holes???

http://imgs.tootoo.com/fc/48/fc4836a2308ddad9bebfd8b77cfa7cf4.jpg

Or this::

http://res.aecdaily.com/res/53/01/39/opencell.jpg

 

[KLH]

Thanks everyone for your prompt responses. I'll probably end up locating sprinklers above and below.

Thanks again.

 

[cdafd]

Cold soldering????