The problem of cavitation in self-priming pumps
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The rated flow rate of the self-priming pump is 200 liters, with a head of 30 meters. In actual operation, the flow rate exceeds the limit, reaching 280 liters; can this lead to cavitation? ? Why does cavitation occur easily when the outlet valve is opened wide and the flow rate exceeds the rated value?
These are the characteristics of a centrifugal pump; describing them solely in terms of cavitation seems insufficient. When using such pumps, it is essential to adjust them according to the pump’s rated current. If it is a system-related issue, the main return water valve should be used to control the amount of return water. This is a systematic control method: instead of using an outlet valve to regulate the current, it is the main return water valve that is used to control the system pressure and flow rate. For reference.
Thank you for your reply. Let me understand further – it’s usually not a self-priming pump but a centrifugal pump; I always keep the outlet valve fully open, and cavitation has never occurred. Self-priming pumps, with their high flow rates, are prone to cavitation; I really don’t understand why
Cavitation is an inherent characteristic of pumps; if the cavitation conditions in the system are not suitable, cavitation will occur in the pump； For example, if you fully open the outlet valve of a regular centrifugal pump, the cavitation level of the pump will be 10 meters at that point; since your system’s net positive suction head is much greater than 10 meters, cavitation will not occur ； Conversely, if the opening degree of your self-priming pump is not matched to the system conditions, cavitation will occur. It has nothing to do with whether it is a self-priming pump or not!
Just take a close look at the performance curve of the centrifugal pump and you’ll understand
There are no two pumps with exactly the same performance, nor are there two sites with exactly the same operating conditions; therefore, it is not possible to make general statements.