Centrifugal pump surge refers to the wheezing phenomenon of the pump in the process of conveying medium fluid. When the liquid medium flows out intermittently, it leads to the periodic violent vibration of the pump discharge pressure and flow, making the pump run unstable.
Cause analysis of centrifugal pump surge
1. The pump automatic exhaust valve fails to exhaust the air in the pump in time;
2, the pump inlet flow channel is small, resulting in the pump inlet flow rate is too large, so that the vortex phenomenon occurs at the pump inlet;
3. The local roughness is too large at the inlet of the pump impeller;
4, the water pump inlet pipe has irregular and can move debris, the entrance section changes irregularly, resulting in high flow rate of the water pump inlet, resulting in the water pump cavitation;
5. The sealing at the junction of the pump outlet pipeline is not good, resulting in insufficient displacement of the pump exhaust valve.
When the pump cavitation occurs, this phenomenon is called "cavitation surge". Even if the head and flow curve are negative slope, cavitation surge will also occur. For example, when there is a hump in the performance curve of low specific speed centrifugal pump, it may lead to surge under unstable conditions.
Centrifugal pump surge elimination method
1, check whether the pump automatic exhaust valve is flexible and reliable;
2. Solve the problem of vortex at the inlet of the pump due to the small flow at the inlet and too large flow rate at the inlet;
3. Check whether the impeller and shell of the pump have defects;
4. Check whether there are movable foreign bodies at and near the inlet of the pump;
5. Check whether there is leakage at the junction of the pump outlet pipeline;
6. When starting the water pump, ensure the liquid level at the inlet of the water pump;
7. When choosing the hump curve, full consideration should be given to the pump pipeline plan so that the working point of the pump equipment falls in the stable operation area. It is recommended that the pump not work in the unstable small flow area.
8, the pump flow regulating valve should be installed between the pump and the air tank, can not be installed behind them, or the pump static head can not exceed the closed head of the pump.
Safety precautions for eliminating surge of centrifugal pump
1. Take good safety measures before maintenance of centrifugal pump;
2, in the maintenance, turn off the water pump power switch, power failure measures;
3. When inspecting the water pump in operation, take good safety precautions.
