Many users, before purchasing a water pump, believe that choosing a higher head water pump for a lower head operating condition would result in a wider range of head usage. In this misleading misconception, when purchasing a water pump, the selected pump has a very high head. In fact, for centrifugal water pumps, when the pump model is determined, its power consumption is proportional to the actual size of the pump and flow rate. When the head of the pump is low, the flow rate will increase; As a result, the current is higher, the flow rate is smaller, and the power consumption is lower. On the contrary, reducing the head, increasing the flow rate, and increasing the power consumption. Therefore, in order to prevent motor overload, it is generally required that the actual calibrated head of the pump pumping head should not be less than 60%. Therefore, when a high head water pump is used for low head, it is easy to overload the motor and cause it to heat up, and in severe cases, the motor may be burned out.
If used in emergency situations, it must be adjusted using a water outlet valve installed on the water outlet pipe. Self operated regulating valves (or wooden blocks, and other methods) can usually be used to reduce water flow and prevent motor overload. Pay attention to the temperature of the motor. If the motor overheats, reducing the water outlet flow or shutting down in a timely manner can avoid burning out the motor. Some users force a decrease in flow by reducing the power supply voltage, which will increase the motor load. In fact, on the contrary, the unit outlet pipes of centrifugal pump irrigation stations are equipped with valves to reduce the motor load. Before stopping the water pump, the valves should be closed. After starting the water pump, gradually open the valves to prevent overcurrent during startup.
The pressure of the series connected water pump is cumulative.
The installation should be as follows: the low head water pump should be installed in front of the high head water pump, that is, the outlet water of the low head water pump should be sent to the inlet of the high head water pump. There is a problem here, which is that the outlet pressure of the low head water pump cannot exceed the upper limit of the inlet pressure of the high head water pump, otherwise overpressure leakage may occur.
