I have a water treatment plant with 3 tanks, 9 feet in diameter. The fire protection contractor feels we need to install a sprinkler under each tank, following the greater than 4 wide rule for obstructed construction. The tanks are located on a concrete floor. The tanks are supported on legs, and the clearance from the bottom of the tank to the floor is about 2 feet.
Remembering that code tells us where to install sprinklers; my argument is this is not an occupiable space and sprinklers are not needed. The tanks are part of a water filter system, and not a hazardous type chemical storage. Are sprinklers required underneath these tanks? Any thoughts or input is most graciously appreciated. Submitted anonymously and posted for discussion. Discuss This | Submit Your Question | Subscribe
8 Comments
FIREPE25
8/5/2020 10:10:34 am
Sprinklers are required. Any obstruction greater than 18" below the deflector that is greater than 4' wide needs sprinklers. I believe the 2016 edition of NFPA 13 added some context about not needing them if the obstruction was close enough to the ground, but I am not sure on the exact language.
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James
8/5/2020 10:11:40 am
Additional protection under the tank should not be required provided the bottom of the tank is 24" or less from the floor.
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Paul
8/5/2020 11:16:13 am
Keep in mind, the 24 inch clearance was only added in the 2016 Edition of NFPA 13, so may not be adopted everywhere. This has not stopped me from submitting a variance/equivalent design to the AHJ's for approval, which most circumstance a valid argument/discussion allowed it to be approved.
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GLENN BERGER
8/5/2020 11:58:23 am
Sprinklers are required. It will be easy for combustibles or other materials to eventually find its way to this "obstructed" space.
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Mark C.
8/5/2020 01:34:03 pm
Is there a possibility to enclose the area below the tanks? If a noncombustible or limited-combustible concealed space is created, Section 8.15.1 allows for certain concealed spaces to not require sprinkler protection. If access for any type of piping or maintenance is required below the tanks, 8.15.1.2.2 specifically may still apply:
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Jonathan Joseph
8/5/2020 01:49:43 pm
I would put some kind of wired mesh screen and wrap around the legs so debris will not collect under the tanks if that is an issue.
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Franck
8/6/2020 10:44:55 am
I'm afraid that every body is right (or wrong) and all refernecs are correct (even though they might be contradictory).
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Dale Morris
8/10/2020 10:57:31 am
I want to thank you all for your input. At the time I posted the question, I was not informed of the actual space under the tank. The clearance is 9 inches from the bottom of the tank to the floor. I love the idea of placing some mesh around the bottom to keep trash from accumulating under the tank.
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