Pump Question

[Dymalica]

I don't quite understand pumps. Lets say you have a Vertical Turbine Pump. The pump curve is what you will see basically at the outlet of the pump in terms of pressure and flowrate because there is basically no suction side friction loss. Lets say you have an inline pump that was designed for 200 GPM at 50 ft, and the water balance comes back at 200 GPM, but the differential pressure says Final Discharge Pressure 39 ft and Final Suction Pressure of 9 feet, and Final Differential pressure of 30 feet. What exactly does that mean? How does that relate to pump curves? Does that mean the actual loss through the piping is 30 feet and not 50 feet as anticipated?

 

[KiwiMace]

The pump curve is differential pressure, so disregard static pressure (unless you are looking at NPSH which is another matter also important). If you have a pump operating on a duty point at say 200gpm and 30ft head, that means the flow in the pipe is 200 gpm and the head at the discharge of the pump is 30ft more than at the inlet. If the pump inlet head is 9ft, then 39ft at the discharge.

Yes, if you thought you were going to need 50ft of head, and your pump dp says 30ft, then you are somewhat off.