We have a fire sprinkler system with a 550 gpm total sprinkler demand (including hose allowances). The supply duration is 60 minutes. There is no city water supply and we are only utilizing a storage tank.
Is the tank required to have a minimum capacity of 33,000 gallons? Or, could we rely on fire department response, potentially reduce the tank size, and have a manual fire department connection for tank refill? Sent in anonymously for discussion. Click Title to View | Submit Your Question | Subscribe
11 Comments
Pete
8/3/2021 06:47:32 am
I might be out of my depth here, but I'm seeing nothing in NFPA 22 even suggesting the idea of a manual refill or fdc connection to a tank. I can't imagine the FDC would be considered listed for such an application.
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Glenn Berger
8/3/2021 08:19:19 am
Your question said that there is no city water supply. To me this implies that the project is located remotely from any municipality that has any type of reliable water supply.
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Michael Newell
8/3/2021 08:21:12 am
It would be based in my opinion on worst case scenario. If you do not have a water supply you could in theory be required to have fire fighting water storage as well. But this would potentially increase tank size depending on system and demand instead of reducing it. I wouldn't think the AHJ would allow you to reduce the system demand below what is required for your system duration.
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Roland lopez
8/3/2021 08:21:57 am
Based on NFPA 13 & 20. It is required for your safety. You can reduce the tank size if proximity of Fire department is very near and will not take a longer time to response… say within 10 minutes arrival of fire department. Immediate source of water is essential in supressing fire.
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schulman
8/3/2021 08:24:26 am
with no "city water supply" you'd get approximately one minutes worth of water from a pumper truck ... FYI ...
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MattC
8/3/2021 08:49:36 am
If you can prove that the fire department response is really fast, and the department has tanker/shuttle accreditation then this may warrant or justify the reduction in tank sizing. Of course you're at the mercy of the AHJ and they likely want as much water on-site as possible.
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Anonymous
8/5/2021 07:33:56 pm
That last part was very helpful, thank you
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CJ Bonczyk
8/3/2021 08:50:54 am
We have ran into this before. If no supply connection is available for the refill rate to be reduced then the tank is required to be sized for total demand at the duration required. If the refill rate cannot be refilled within 8 hours per NFPA 22 a variance from the fire department can be requested to where they will connect their mobile tank truck (if the department has one) to help with supply refill once on scene.
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Casey Milhorn
8/3/2021 09:19:59 am
Yes, full amount with no reduction. Also as someone else mentioned there should probably be the conversation about IFC fire flow if any draft hydrant or private hydrants are to be fed from the tank. A good compromise would be to add a draft hydrant on the tank, size up to 40,000 gallons, and the fire department at least has a little extra in there for drafting from the tank. From the sound of the demand, you might be ordinary hazard group 1 or 2. Make sure the building has offsite monitoring of fire alarm so that you can truly use the 60 minute duration. Also, if there is no draft hydrant or private hydrants, you could argue that the hose allowance is not needed but again a draft hydrant would probably be a good idea anyway.
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Franck
8/3/2021 04:37:01 pm
Insurance point of view : not acceptable (as many other point of views above)
Reply
Alex
8/4/2021 06:59:25 am
Anonymous,
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