So I'm more into electricity, so fluids is not really a forte at all. But I have been thinking about this, and there must be some fundamental issue in the way that I view fluid pressure. Conditions: 1. I have a metal pipe, incompressible 2. There is water in the pipe, (incompressible? ... I thought) 3. There is a pump on one end of the pipe, supplying 150PSI 4. There are discharge and suction pressure gauges attached to the respective pump locations 5. There is a deadhead on the other end of the pipe Actions: 1. while the pump is running, I close a perfect valve (whatever type) that does not leak by on the discharge side of the pump. 2. I stop the pump. Questions: 1. Is there 150PSI in the pipe? 2. Where does the pressure come from? What has compressed to allow this pressurization? Actions: 1. I have a discharge pipe (on the same level as the pump (i.e. no head pressure) 2. I have a suction pipe (on the same level as the pump (i.e. no head pressure) 3. The pipes are filled with water before the pump starts (assume pipes match pump gpm) 4. Start the pump Questions: 1. How does the gauge read actual suction pressure when there is no attempt for anything to expand on either side of the pump 2. same for discharge, if there is nothing restricting flow, how does the pipe gauge read any pressure in the pipe?