sizing requirements for storage tanks to be used for fire protection

[sparky9]

I have a 22,000 sq ft building, extra hazard 30gpm per 3200 sq ft, (extra 30% for dry type), what size of water storage tank is needed for the 60/90 minute requirement for supply?

 

[hydrae]

22,000/3200*30*1.3*90 for the 90 minute supply
but there may be more to this, have read the relevant codes?
Hydrae

 

[TD2K]

Check also with your local fire marshall or whoever has jurisdiction in this area.

 

[ash9144]

Ask your insurance provider.

 

[PEDARRIN2]

Be careful with using code minimums.

We designed a system for a 1000 gpm fire pump for 30 minutes - the majority of the building is light hazard - so we came up with 30,000 gallons

Our worst hazard is an ordinary hazard which would be 0.15*1500*1.3 and add 100 gpm for inside hose - no outside since our supply was the tank. We multiplied by the 60 minutes and came up with 23,550 gallons.

We designed for a 30,000 gallon storage tank to cover the worst case.

The sprinkler contractor came back with hydraulic calcs where his worst zone was 600 gpm which when multiplied by 60 minutes was 36,000 gallons required. He had a lot more sprinklers than we anticipated (26 in an area of 1664 sq ft) and the flows/sprinkler were in our opinion excessive.

The plans examiner rejected his plans - and questioned our tank size based upon the hydraulic calcs.

We have plausible and defendable position based upon how we are filling the tank, but if we didn't we would be in a difficult postion.

I have always taken the standpipe demand when sizing my tanks - now I will pay a little more attention to possible sprinkler demands that exceed the hoses.