Export of centrifugal pump on startup, pump haven't water in the pipeline, so did not exist pipeline resistance and improve high resistance, the centrifugal pump starts, the pump head is low, traffic is very big, the pump motor, shaft power output is very big, according to the pump performance curve), it is easy to overload, it can make the pump motor and the circuit are destroyed, therefore starts to close the outlet valve, can make the pump normal operation.
If the axial flow pump is the other way around, it is necessary to open the valve to start. At this time, the power of the motor is very small in the short term, there is no resistance to vibration, and it will run in large flow. There are often pump vibration, noise, and even overload operation of the motor, which will burn out the motor. Close the outlet valve, equivalent to artificially set pipe resistance pressure, with the normal operation of the pump, gradually start the valve, so that the pump along its performance curve law gradually normal work.