head loss

head loss

[′hed ‚lȯs] (fluid mechanics) The drop in the sum of pressure head, velocity head, and potential head between two points along the path of a flowing fluid, due to causes such as fluid friction.

pressure drop

The decrease in fluid pressure between two ends of a duct or pipeline, between two points in a system, across valves and fittings, etc., due to frictional losses; in a water-piping system a drop in fluid pressure also occurs between two points as a result of the difference in elevation between the two points.