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Fire pump sizing

Question asked by rigoberto on Aug 28, 2019
Latest reply on Aug 30, 2019 by milt.werner

Need help. I need to size my fire pump for ordinary 1. This is a fully sprinkler parking garage with 6 floor 72' high. 

Below are the details:


Flow test data:

Static Pressure: 70 psi

Residual Pressure: 65 psi

flow at 20psi= 3,039 gpm


* Most remote sprinkler demand 225gpm @min. residual pressure at system inflow node= 72psi 

* Hose allowance for Ordinary 1 = 250gpm, @ 65psi per NFPA 7.8.1 for 1-1/2" hose most remote outlet


My initial pump selection is 500 gpm, 40 psi. 20 bhp. Is this ok?


What if the pressure of the hose allowance is greater than the sprinkler pressure requirement, do I need to consider the pressure requirement of the hose?

Or can we supply the hose from the wet standpipe riser or loop and sizing the pump with only the sprinkler demand?


Note: This is a manual wet stand pipe system.


Thank you in advance.