Adjust the operating status of the water pump
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Two water pumps are in operation on site, with one as a backup. One of the pumps has its inlet fully open and its outlet at 40°; cavitation has already occurred. How should this be adjusted to alleviate cavitation in this pump?
Is there one with both the inlet and outlet open? Adjust the two outlet valves to similar angles or openings.
Currently, the combined flow rate of the two pumps is 3000; if the other pump is adjusted (to 45°), the flow rate may not be sufficient.
Could it be that the water temperature is too high? Could it be that the pump is at a higher height than the water surface, resulting in an excessively long suction distance?
Pumps with the outlet fully open work fine, but do they suffer from cavitation when operated at 40% capacity?
Exactly, there is cavitation. How to adjust it to alleviate cavitation
Typically, the cavitation curve of a pump is curved at both ends. If the two pumps are of the same type and connected in parallel. And if there is no cavitation at high flow rates but it does occur at low flow rates, I believe this is either due to an obstruction at the pump inlet for low-flow conditions, or because the flow rate is too low and thus outside the stable operating range. If the inlet is blocked, checking the inlet will resolve the issue. If the issue is caused by too low flow rate, which results in an upward curvature of the cavitation curve, then balancing the flow rates of the two pumps (by reducing the valve opening on one pump and increasing it on the other) should resolve the problem. This is just my personal opinion; I welcome any differing views for discussion.
The two pumps have the same head; when they are in operation, one operates at 2400 while the other at 1600. Their flow rates differ, and cavitation occurs in the pump with a flow rate of 1600. Currently, the inlet and outlet of the larger pump are fully open, while those of the smaller pump are open at 45°. An export blockage is unlikely. Cavitation may be caused by the small outlet of the pump and the large diameter of the main pipe. This leads to cavitation due to high flow rates. Currently, operating the small pump at its outlet causes overcurrent.
It is recommended to check the pump inlet pipe to confirm whether there is any blockage caused by debris. Furthermore, it involves checking and confirming the wear condition of the mouth ring.
Oh, if the pump types of the two pumps are different, they need to be considered separately. What I just said was blockage at the inlet, not at the outlet. The outlet of the small pump is very small; no matter how thick the inlet pipe is, the flow rate cannot increase. If cavitation occurs due to high flow rates, closing the outlet valve further should eliminate the cavitation phenomenon, which is quite easy to determine.