Firewater tank capacity.

[Miyazaki]

Hello Members,

Could anyone please guide me in considering the exact size of a firewater tank, as per my calc the min storage capacity is 227.10m3 (60,000 gals). My concern is don't we need to consider some clearance for the PRV line, test line and some clearance for the water overflow. As per NFPA 22, I saw only the design guidelines in construction and installation of the firewater tanks, regarding sizing not much is written apart from considering the standard sizes. The firewater tank MOC is FRP.

 

[FacEngrPE]

NFPA standards are safety codes, not design cookbooks.
Try the FM Global Guideline "Water Tanks for Fire Protection" 3-2 July 2021
Some dimensional suggestions for break tanks can be found on page 7.

 

[Miyazaki]

@FacEngPE thanks for the reply. Will go through the FM datasheet.

 

[UFT12]

The PRV could be connected to the test line. You would need to consider test line, overflow and floating vlave(s). The floating valve is nearest to the final water level with the other a bit higher. Typically the test return should be a bit heigher than the overflow pipe. So consider the pipe sizes plus some clearance.

 

[mk3223]

My concern is don't we need to consider some clearance for the PRV line, test line and some clearance for the water overflow.

Yes, it's correct. You may add these quantities to the tank "minimum" storage capacity as required by the Project Spec.