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Roof height for sprinkler K5.6

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sprinkler1000

Mechanical
Sep 18, 2010
117
Sirs:

I understand that there is no limit for roof height (deflector height) in NFPA 13 for sprinklers with 5.6K.

Beyond that, is it good practice to design with 5.6 K at 60 ft, or they should be with a higher discharge coefficient? I have read discussions on this issue about vaporizing of wáter but have found no technical basis to provide a higher K.

Occupancy is Convention Center, taking it as OH II.

thanks
 
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For about the past decade, I have used 5.6k up to about 20' ceilings. K8 up to about 30' ceilings and K11.2 above 30'. I honestly can't remember where that came from, but it made a lot of sense. So, out of habit, I have stuck with that. There may be some data in the FM guidelines to support higher k-factors for higher ceilings.

Travis Mack
MFP Design, LLC
 
Is that your density or the density specified by the Engineer of Record? Convention centers require some very close considerations due to the diversity of exhibitors.
 
Thanks both for replying.

I will look deep in FM datasheets. I think your approach is sound.

stookeyfpe: we are the designers, there is no engineer of record. We think that going beyond OHII may be overkill. Maybe we should clarify what kind of exhibitions are not protected.

 
In my little town of 3/4 million we've seen some big boats at the Boat Show, folks trying to build a 2-story apartment inside a convention hall, and a welding trade show where they wanted to bring several thousand cubic feet of flammable and oxidizing welding gases to demonstrate the capabilities of welding robots.

I believe it would be prudent to clearly state the limitations of the sprinkler system based on the NFPA 13 definition on the shop drawing. Also, I seem to recall that maybe GE GAP has guidance for the protection of large convention centers.

At the end of the day, the local fire code official should be considering all the variables.
 
Stookey:

By GE GAP you mean Global Asset Protection? Are they fire protection related?. The two organizations that we follow are NFPA and FM. At least in NFPA 13 there is no explicit reference to the occupancy.

Here the AHJ has no requirements for sprinklers, but there are some expceptions in the fire compartment requirementes if they are provided.

Providing for EHII would be the most conservative approach but we are not sure.
 
That is a tall ceiling. FM has done testing on high ceilings. Check out Data Sheets 2-0 and 3-26.
 
And what Stookey said. You are going to get every conceivable occupancy under that ceiling. Not saying you can completely quantify that, but your fire loads will be dynamic.
 
thanks Sdpaddler, I will check FM.

Maybe OHII is not adecuate.
 
I have not looked at the high ceiling tables for a long time. I believe FM increases the area of operation to account for the delayed head operation and subsequently more heads popping Later in the fire growth as opposed to a lower ceiling.
 
Sdpaddler.

Bingo: in tables 3 to 5 in DS 0200 there are the spacing rules for sprinklers, depending on the hazard category. There is no 5.6K sprinkler for roofs over 30 ft.

Also in DS 3-26 the demands are related to ceiling height (table 2)

Thanks for your help.

 
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