With the pump turned off, what is the difference in elevation between the suction and discharge liquid levels called?

The difference in elevation between the suction and discharge liquid levels with the pump turned off is referred to as static head. Static head represents the potential energy of the liquid due to its elevation above a reference point, typically measured in feet or meters. This measurement is crucial in pump selection and system design because it indicates the height that the pump must overcome during operation when moving liquid from a lower elevation (suction side) to a higher elevation (discharge side).

Static head is particularly important because it is one of the key factors that influences the required pump capacity and operational efficiency. It provides an understanding of how much energy must be supplied by the pump simply due to gravitational forces acting on the liquid. Understanding static head helps engineers ensure that the system is designed to handle the necessary liquid movement without running into issues like cavitation or insufficient flow.

The other concepts, such as pressure head, dynamic head, and flow head, relate to different aspects of fluid mechanics and pump performance, but they do not specifically address the elevation difference in a static scenario with the pump off.