Is the actual head at the centrifugal pump outlet equal to the pump’s outlet head minus the difference in liquid level between the inlet and outlet?
Thread Content
If there is no pressure at the inlet, is the actual head A at the pump’s outlet simply equal to the pump’s outlet head B minus the difference C between the liquid level at the inlet and the height of the pump? In other words, if the liquid level is below the centrifugal pump, then A = B – C； If the inlet liquid level is above the centrifugal pump, then is A=B+C?
This post was last edited by wawa*n*ntaozi on 2017-8-29 at 16:57. It can be understood in this way: the pressure of the liquid surface at the inlet as well as the height difference between the liquid surfaces at the inlet and outlet must also be taken into account. Head is an inherent property of centrifugal pumps and is independent of external factors. The outside environment merely provides the conditions for achieving head pressure.
Calculate using Bernoulli’s equation from chemical engineering principles. The outlet pressure is converted to a liquid column height.
Head is a characteristic of the pump; once the pump is selected, the head is essentially fixed, and it only changes with flow rate. The liquid level height corresponding to the outlet pressure should equal the difference between the head provided by the pump at a specific flow rate and the inlet liquid level height
Perhaps my way of phrasing it has made you take it too seriously; let me put it this way then: when there is no pressure at the inlet, is the pressure A at the pump outlet equal to pressure B, which is calculated based on the head corresponding to a specific flow rate, plus pressure C, which is calculated based on the height difference of the liquid level at the inlet? From the back, it seems you agree with this statement as well
That’s not right of you. The centrifugal pump must be installed below the liquid level. Include the reserve pressure when calculating the head.
It doesn’t work at all when it’s below the liquid surface; nothing can be done in such a situation.
This post was last edited by I have something to say on 2017-8-30 11:52. The actual head of a centrifugal pump is determined by the characteristics of the pump itself and those of the piping system. Once the pump is selected, its head is determined. However, since the pump is installed in the pipeline, the actual operating head is determined by the characteristics of the pump and those of the pipeline. The pipeline characteristics can be determined using Bernoulli's equation. The actual operating head is the intersection of the pump’s characteristic curve and the pipeline’s characteristic curve, which is also the operating point. What we hope for is that this operating point be close to the pump’s theoretical head. How do I understand it?