we have a diesel and electric pump operating in auto mode.
As per NFPA 20, the pressure setting for the pump shall be churn pressure+ static pressure.
while doing the actual performance test, the churn pressure( zero flow) was found to be 170 psi. while as per the manufacturer pump curve, the pump shut off( at 140% of rated head) is 105.5 psi only. Which pressure setting should be considered (170 or 105.5 psi) to set the churn pressure.
Diesel pump is 145 psi-750 gpm
Electric pump-161psi-750 gpm