Water sprinklers to fight fire above false ceiling "pockets "

[DrClassic]

Good Morning all
In NFPA 13 it is stated that if distance between slab bottom and false ceiling is 900 mm or higher additional sprinklers will be installed to protect this "pocket " above false ceiling .
The conditions under which those sprinklers should be installed are not clear , i.e. when it is must and when it is optional .
If we have no thing other than steel pipes and fireproof materials , why should we spend this extra money .


(1) The total volume of the unprotected ceiling pocket does
not exceed 1000 ft3 (28.3 m3).
(2) The depth of the unprotected ceiling pocket does not
exceed 36 in. (914 mm).
(3) The entire floor under the unprotected ceiling pocket is
protected by sprinklers at the lower ceiling elevation.
(4)*The total size of all unprotected ceiling pockets in the
same compartment within 10 ft (3 m) of each other does
not exceed 1000 ft3 (28.3 m3).
(5) The unprotected ceiling pocket has noncombustible or
limited-combustible finishes.
(6) Quick-response sprinklers are utilized throughout the
compartment.
8.6.7.3 Sprinklers shall not be required in skylights and similar
pockets in accordance with 8.5.7.

 

[tygerdawg]

I'm NOT an expert, and perhaps you should consider engaging one.

One of my many jobs was Facilities Manager, in which I had deep discussions with the Factory Mutual Insurance Company Guy about fire protection. We had industrial warehouse multi-level racks of flammables and the FM Guy recommended putting sprinklers in each level of the racks. The reason: sprinklers in "normal" position up high would not cover fires down at the floor. The water spray would be diverted by materials. The fire, if it happened, would have time to build up into something significant and difficult to manage. Thus his justification for the extra cost.

What came out of several days with the FM Guy was a fire-protection philosophy that most fires are not a single event, but the result of a worst-case scenario of a cascading series of unlikely events that ultimately results in the facility burning to the ground.

Certainly this is not your situation. But you have to ask yourself about that unlikely series of events happening at your place. Maybe a FMEA analysis would be in order to help clarify the likelihood, and thus provide guidance on assessing the risk. Would some extra expense make sure a worst-case scenario doesn't happen? The sprinkler headers are going to be run, and that is the bulk of the expense isn't it? Providing redundant drops isn't that much more cost, especially if the risk has been established.

TygerDawg
Blue Technik LLC
Virtuoso Robotics Engineering

http://www.bluetechnik.com

 

[3DDave]

I agree with tygerdawg - look for an expert.

For further examples, it may be the location has no flammables, but it could serve as a place for flammable gases or liquids or dust to collect and ignite or for high temperature combustion gases to pass through and set other things on fire.

I suppose money can be the judge - if the fire-insurance company cuts their rate based on the additional protection, it means they believe it is useful.

 

[chicopee]

The statement " The depth of the unprotected ceiling pocket does not exceed 36 in. (914 mm). is probably based on fire tests. Do research on fire science that led to this requirement. False ceiling have all sorts of electrical wiring and recessed lighting that could be sources of fire. Also check NFPA 13 carefully for exceptions.

 

[berkshire]

Why don't you re-post this thread into forum 184 NFPA ( fire) code issues. Link it to this forum so that people know it is an additional post.
B.E.

You are judged not by what you know, but by what you can do.

 

[DrClassic]

Thanks to tygerdawg , 3DDave , chicopee , berkshire for their esteemed replies .
Dear berkshire Kindly give me the link to this forum .

 

[DrClassic]

Link to the thread in NFPA Forum

http://www.eng-tips.com/viewthread.cfm?qid=414841

 

[chicopee]

I know that the NFPA publishes certain code handbooks (not the codes themselves) one of which I have on flammable and combustible liquids. These code handbooks explain past and current logics to their codes. See if NFPA has a handbook on nfpa13.

 

[moon161]

I used to work in a call center without a drop ceiling, and thus no plenum. You could look up and the cable trays of cat. 5 Ethernet cable looked like gray rivers. This is one source of combustion in the plenum I could imagine.