On Monday, May 29, 2017 at 7:20:01 PM UTC-4, wrote:


If there is no flow, there will be no pressure differential. Pressure will be the same throughout the volume of liquid from inlet to outlet.

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Ed Huntress

If you have a column of water, the pressure at the bottom of the column in higher than the pressure at the top. So there is an example of no flow with a pressure differential.

If you take something like say a large nut and tie a string to it and whirl it around your head, then you have a force on the string and a velocity of the nut. But the nut does not go flying off , unless you let go of the string.

In the same way with the outlet blocked off on a centrifugal pump. the water has a velocity , but it just goes around and around. Produces a pressure, but no flow from the pump.

Think of a centrifuge with test tubes in it. The material in the test tubes are subjected to force, but there is no flow.

Dan