Advantages of a large inlet diameter and a large outlet diameter in vortex pumps
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This post was last edited by Yixin on 2018-9-19 00:56. While visiting the mechanical and electrical market today, I saw high-pressure vortex pumps from Japan and Italy; I noticed that the diameters of their inlet and outlet ports were not the same, with the inlet port being one size larger than the outlet port. For example, 20mm in and 15mm out. Or an inlet diameter of 25mm and an outlet diameter of 20mm. What are the advantages of this design? Those who know about this please feel free to leave comments or send me a private message; thank you!
https://bbs.hcbbs.com/thread-1182191-1-1.html
The inlet is larger, allowing for a slower flow rate; the inlet pressure does not need to be too low, which helps maintain a larger net positive suction head and reduces the risk of cavitation in the pump. The outlet is smaller, which, as is understandable, allows for an increased flow rate and lowers the costs associated with the piping； From a hydraulic design perspective, it is better to have a smaller outlet, thereby reducing the degree of diffusion within the pump and smoothing out the rate of change in fluid velocity as it passes through the pump, in order to improve efficiency.
Thank you for your reply. I took a look, and that issue is exactly the opposite of my situation regarding import and export sizes. My inlet is larger than the outlet. His inlet is smaller than his outlet. Does this reduce, increase, or leave the head basically unchanged?
That post talked about the diameter change at the pump’s inlet and outlet: the inlet pipeline narrows as it leads to the pump’s inlet, while the outlet pipeline widens after leaving the pump’s outlet. It is all to reduce the flow rate and minimize pipeline losses. The reason your imports are larger than exports is also to reduce the flow rate of the imports and thereby decrease the net positive suction head required by the pump.
The content of the link cannot directly answer your question, but it is related to it; in fact, some of the principles are the same. I hope it can provide you with some insights
Thank you. I have another question: will reducing the flow rate affect the pressure at the outlet of the water pump? In other words, does the head increase or decrease?
The pump’s head remains unchanged; only the pipeline losses at the outlet have changed