Can a check valve in the discharge pipeline be used as a substitute for a foot valve? Can installing a foot valve or a check valve on a centrifugal pump serve as a replacement for a self-priming pump?
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In my work, I encountered large-diameter mixed-flow pumps in which check valves were installed at the end of the outlet pipeline to replace the foot valve at the top of the inlet pipeline, which led me to consider several questions: 1. Can installing a check valve at any point along the entire pipeline suffice as a replacement for the foot valve? This also eliminates the inconvenience of servicing the bottom valve underwater. 2. Can installing a foot valve or check valve on a centrifugal pump replace a self-priming pump? Since the water in the pipeline does not flow back and no air enters the pipeline, there is no need to release air when starting it up again. 3. After installing a foot valve, how should the water intake distance (suction lift) be controlled? For example, what is the maximum suction lift possible when a centrifugal pump is equipped with a foot valve or check valve? After installing a foot valve or check valve on a self-priming pump, can its suction lift exceed the typical maximum of 7–9 meters?
1. No, the opening pressure of the valve needs to be taken into consideration. 2. While ensuring that the valve does not leak, it is also necessary to ensure that the pump’s shaft seal does not allow air leakage, and that all flange gaskets are leak-proof. 3. Once the pump is manufactured, its net positive suction head is determined. Adding bottom valves and fittings only increases the local piping losses in the inlet pipeline, thereby reducing the self-priming height.
Set the flap; what is this flap? ?
I think he is referring to a double-leaf check valve
Door valve: A check valve installed at the end of the drainage pipe, designed to prevent backflow of external water. The door closer is mainly composed of four parts: the valve seat, the valve plate, the sealing ring, and the hinge. The shapes are divided into circular and square.
Thank you for your reply. 1. If the opening pressure of the check valve used is the same as that of the foot valve, can the check valve replace the foot valve? For example, installing a check valve in the vertical suction pipeline instead of a foot valve? Additionally, I read in a specification for the piping layout of self-priming pumps that installing a check valve on the outlet pipe could affect the expulsion of air
Thank you for your reply. 1. If the opening pressure of the check valve used is the same as that of the foot valve, can the check valve replace the foot valve? For example, installing a check valve in the vertical suction pipeline instead of a foot valve? Additionally, I read in a specification for the piping layout of self-priming pumps that installing a check valve on the outlet pipe could affect the expulsion of air
Yes, it’s this knocking on the door. The mixed-flow pump manufacturers say that large-diameter mixed-flow pumps generally have a check valve installed at the end of the outlet pipeline, to replace the foot valve at the top of the inlet pipeline. But I wonder that if I do this, how can I fill the suction pipe with water on the first start of the pump? If it’s not equipped with a vacuum pump for exhaust, it can’t be used; water will leak out through the suction pipeline. If a foot valve is used, there is no need for a vacuum pump; filling the suction pipeline and the pump body with water is sufficient to pump water. I was wondering if that’s indeed the case?
It’s possible, then why make two types of valves? Bottom valves are cheaper than check valves. For outlets equipped with check valves, a vent line must be connected to the pipe between the check valve and the pump outlet flange. Close the pipeline only after all liquid has come out of the exhaust pipe.
No vacuum pump is required; a foot valve can be used – simply fill the pump and the inlet pipe with water. The mixed-flow pump together with the check valve you mentioned is mainly used to prevent liquid from flowing back and to avoid water hammer. The function of a door latch is similar to that of a check valve, and its price is definitely lower than that of a check valve. Is your mixed-flow pump operating in reverse flow or suction mode (is the liquid level higher or lower than the pump inlet)?
The liquid level of the incoming water is lower than the pump inlet, so it is drawn in.