Sprinkler Spacing Only Cover Each Cloud Ceiling?

11/11/2020

I have a project with cloud ceilings that are 80 sqft clouds with a 2-foot separation around each cloud. I have no intention of omitting the sprinklers above the clouds. I plan to locate sprinklers in each cloud, considering them obstructions greater than four feet.

Do I need to space the sprinklers in the clouds to just cover beneath the cloud?

Just want to confirm that spacing doesn't need to be across the cloud ceiling when sprinklers are in different clouds. Thanks in advance.

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2 Comments

Dan Wilder

11/11/2020 10:08:48 am

Correct (IMO), you are covering the floor space that is obstructed by the cloud ceiling. If your room is 36' wide and you have 2-15' wide clouds and 2' clear between, placing 2 pendents centered in the cloud is acceptable even though the pendents would be 17' apart and 9'-6" from each wall. The heat is expected to roll by the lower clouds and activate the upper level sprinklers.

This would not be an acceptable solution if you were omitting sprinklers above the cloud ceiling.

Franck

11/12/2020 08:44:14 am

As indicated by Dan, you have to protect the ceiling according to the occupancy and the sprinklers below your clouds as for obstructions below the ceiling sprinkler deflectors.
The only limitations are the maximum spacing below the same obstruction to follow NFPA 13 according to occupancy :
15 ft max for LH and OH
12 or 15 ft maximum for EH

But there is no limitation of max spacing between 2 obstructions (if they are located 2 ft apart or 10 ft apart does not matter), except if the sprinklers below each adjacent obstruction may be located less than 6 ft on center (in that case, you need to install baffles to protect actuating elements).
Which could be the case depending on the size of your obstructions and the distance between them... But you should normally be able to design your system to avoid this configuration.

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