Static pressure of pipeline
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Normally, in a high-pressure centrifugal pump, when the outlet valve is closed, and if the check valve is in good condition, pressure will build up between the check valve and the outlet valve. I would like to ask everyone: the pressure of the liquid is generated by the rotation of the motor while the pump is running; so why does the liquid still have pressure once the pump stops? We all know that pressure arises when liquid gets trapped between the check valve and the outlet valve. Liquids are generally considered incompressible fluids; so, when the pump that was used to circulate the liquid stops working, does the trapped liquid get compressed, thereby generating pressure? I hope fellow sailors can provide some guidance
During operation, we can also consider the liquid to be a medium for pressure transmission; then why is there still pressure when the pump stops?
To your question, I can say quite clearly that it has no practical significance, and it’s obvious that your theoretical knowledge from university isn’t very strong either； The kinetic energy of the liquid is provided by the water pump; in other words, it is generated by the rotation of the impeller. If all your assumptions hold true (that is, the check valve closes instantly), then pressure will exist between the check valve and the valve downstream of it ； The liquid will be compressed, but you should thoroughly investigate what the value of this compression coefficient is ； In practice, when a check valve closes due to gravity, the slight compression of the water along with the resulting pressure cause the water to flow back out. Moreover, even in the case of gases with high compressibility, they cannot be held closed by a check valve alone; leakage will occur regardless. . .
Thank you for your guidance, Haiyou. In practice, it is indeed a problem when pressure builds up in the pipelines while the gasification furnace is operating normally; this pressure buildup occurs because the valves close automatically when the pressure drops. As for the pressure levels, I’m not entirely sure either, so I hope you won’t laugh at me
Will liquids be compressed at a pressure of 7 megapascals?
Will a liquid be compressed at 7 MPa?
Young man, it shows just how bored you are – having nothing better to do than to argue here. . . At 7 MPa, the compressibility of water is 0.3%.