During the water test of the centrifugal pump, cavitation occurred when the temperature rose to 40°
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The pump has an effective NPSH of 8.17 m, while the required NPSH is 6 m. During water testing, the liquid level was at a height of 5.6 m above the pump inlet, and the pump’s flow rate was 500 cubic meters
The parameters on the nameplate of the centrifugal pump are tested using water at 20°C
The height for your experiment is also quite high; the standard requires that cavitation tests and performance tests on pumps be conducted using water at 20°C, and this can be used for conversion purposes.
5.6 meters? That’s a pretty high suction height. Wasn’t the manufacturer present during the performance tests?
The inlet is 5.6 meters high, which means the NPSHa is only 5.6 meters, so cavitation will occur.
The inlet liquid level is 5.6 m. Is the air pressure at atmospheric pressure? So NPSHa is 15.6m then? Logically, the saturated vapor pressure of water at 20 degrees is 2.34 kPaA, while at 40 degrees it is 7.38 kPaA; the difference is approximately 0.05 MPa, so this error can actually be ignored
In the case of an open system, the net positive suction head is 15.6 minus the inlet resistance. Please check the condition of the entrance.
What's going on? Once installation at the site is complete, water testing? ? ? The simplest approach is to install a pressure gauge and a temperature gauge at the pump inlet, read the values, and use them to determine the excess pressure at the inlet~~