Protecting Small Storage Lockers (30 SF) with 2.8-K Sprinkler to Avoid Pump

[Haldorson]

I have a 10-storey noncombustible residential building that is being equipped with an NFPA 13 (2013) sprinkler system.

The ground floor storage room has stacked individual lockers that are each 30 square feet and have solid separations so each locker requires a sprinkler. With area reductions for QR sprinklers and ceiling height, the resulting calculation is 1000 SF, OH-2, and is flowing 29 sprinklers. The only way this calculation works is if 2.8-K sprinklers are used in the storage lockers. Is a 2.8-K sprinkler permitted or must it be at least 5.6-K? Since the storage does not exceed 12-feet I would categorize this storage as Miscellaneous.

 

[TravisMack]

8.3.4.2 of the 2016 edition states that k-factor less than 5.6 is for light hazard only. 8.3.4.3 gives the option to use for exposure protection. Since your situation is neither of those, you are limited to K5.6 or larger. I can see your sprinkler system easily being 500-600 gpm demand, not including the hose allowances.

How are you doing this building without a pump anyway? 10 stories (assuming 10.5' per floor) means you have automatic standpipes as this would be a high rise. You need to provide 100 psi at the top of the standpipe. There is ±5-10 psi in loss for the hose valve, nipple, welded outlet, etc. That puts you at about 110' for the elevation of the hose valve at the roof. That is close to 45 psi in elevation losses. Even if your friction losses are only 10 psi, this means you have 160 psi at a minimum of whatever your standpipe demand flow (500, 750 or 1000 gpm) at the ground floor.

If you are getting that to work without a fire pump, then you should easily be able to get the ±500-600 gpm storage locker demand to work. You may not get by with 2" CPVC mains, but 500 gpm is what you flow in a 4" standpipe, so you should be good with 4" mains in that area.


Travis Mack, SET, CWBSP, RME-G
MFP Design, LLC

http://www.mfpdesign.com

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[Haldorson]

Agreed, thanks Travis.

Regarding the requirement for a pump, our provincial code does not require one if we can demonstrate compliance with NFPA 13 and the building is serviced by a mobile fire pump (fire truck).

 

[cdafd]

Fire truck hum

That is s new one for me and interesting


What is your normal main pressureinto a building ??

 

[TravisMack]

Regarding the requirement for a pump, our provincial code does not require one if we can demonstrate compliance with NFPA 13 and the building is serviced by a mobile fire pump (fire truck).

Are you able to get a 10 story building from the city water supply without a pump? I guess I don't understand how you can demonstrate compliance with NFPA 13 if you don't have adequate pressure from your automatic water supply. It would be interesting to know what your source water supply test indicates.

Travis Mack, SET, CWBSP, RME-G
MFP Design, LLC

http://www.mfpdesign.com

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