Everyone, please help determine whether there is cavitation in my pump
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This post was last edited by Xin You Meng Hu on 2016-4-26 at 17:18. There are some issues with the on-site pump that I’m not quite able to understand; I hope everyone can provide some explanations. First, there is a three-way control valve before the pump, which creates significant resistance. The situation on site is as follows: with my 150-mm pipe, when the flow rate reaches 80, the outlet pressure gauge shows 250 KPA, and the flow rate can no longer increase. (The pump has parameters of 200 m3 per hour and a head of 50 m, with a net positive suction head of 4.6 m.) The sound of the pump on site is not normal; it is preliminarily determined that cavitation has occurred. Then the problem arises: the pipe next to me is an 80-size pipe (an adjustable valve with an 80-inch diameter), and it works normally when a flow rate of 60 is used. If the first scenario indicates cavitation is occurring, then shouldn’t cavitation occur even more in the second operating condition? I don’t understand anymore. . . Let me correct the question: it turns out that the same issue is occurring in the second operating condition as well! Since there is no pressure gauge installed before the pump, it’s hard to say for sure, but cavitation has almost certainly occurred! Thank you all for your replies.
Could you draw a simple diagram first and then we can discuss it? It’s hard to understand just by reading it
What is the outlet pressure under the second operating condition?
This is related to the valve structure (bore size and flow direction); among the factors that affect pipeline resistance, in addition to diameter (flow area), length is also very important! !
The pump has insufficient suction, so under these conditions it certainly cannot achieve the rated flow rate. Are two pumps used simultaneously to transport materials within one device? If that’s the case, then it’s the second pump competing for flow.
The outlet pressure is normal. The pump is working properly.
My question is: given that the valve resistance is high (possibly due to cavitation), why does the pipeline under the more severe operating condition function properly, while the one with the larger diameter fails to work properly?
The two pumps are not turned on at the same time. Work alone.
The two pumps are not turned on at the same time. Work alone.
The low outlet pressure of the first pump makes it easier for the material inside the pump to vaporize, resulting in cavitation. Reducing the outlet valve might help, but this will decrease the flow rate. Try increasing the pressure on the input or output device.
Are the two pumps of the same model? If they are the same model but have different inlet pipelines, check whether the first pump is running in reverse. Our factory encountered such a case once – for some unknown reason, a normally functioning pump started running in reverse. If everything seems normal, it’s best to have the pump manufacturer come and take a look to determine if there is something wrong with the pump. If you manage to solve this problem, remember to @ me – thank you; I’d like to learn from your experience