Understanding the Relationship Between Flow Rate and Back Pressure in Pumps

[hanson]

Hi all!
Is a pump having a high maximum flow rate necessarily mean that the maximum back pressure it can handle will be high?

I am a bit confused bewteeen the relationship of flow rate and back pressure...

 

[hanson]

Is the energy output by a pump independent of flow rate and static pressure?

 

[Astronuc]

Is the energy output by a pump independent of flow rate and static pressure?

A flowing liquid (or gas) experience resistance related to friction with the piping. As flow increases, the resistance to flow increases.

Energy is put into the pump, and one must increase the energy as flow rate increases. The pump is less efficient as flowrate increases, because the flow resistance increases. The differential pressure is important with respect to the pump, not the hydrostatic pressure. The work by the pump goes into changing the momentum of the flow.

Hydrostatic pressure is important with respect to cavitation.