1. Selection of pump head
The so-called head refers to the required head, not the height of water lifting. It is especially important for choose the pump. The pump head is approximately 1.15 to 1.20 times of the height of the pumping water. If the vertical height of a water source to the water consumption is 20 meters, the required head is about 23 to 24 meters. When choosing a pump, the head on the nameplate of the pump should be close to the required head. In this case, the pump has high efficiency and will be more economical to use. But it is not necessarily required to be absolutely equal. As long as the deviation does not exceed 20%, the pump can work under more energy-saving conditions. 

2. How big is the head on the nameplate? A pump with a head on the nameplate that is much smaller than the required head will often fail to satisfy the user's needs. Even if it can be pumped, the amount of water will be pitifully small and may even become a useless Takeshi's "idle pump". Whether the higher the head of the purchased pump, the better? actually not. If the pump with high head is used for low head, the flow will be too large, which will cause the motor to be overloaded. If it runs for a long time, the temperature of the motor will increase, and the winding insulation layer will gradually age and even burn the motor.

3. Choose the pump with the appropriate flow rate. The flow rate of the pump, that is, the amount of water, should not be too large. Otherwise, it will increase the cost of purchasing the pump. Specific problems should be analyzed in detail, such as the self-priming pump for the user's own draft, the flow rate should be selected as small as possible; for the user's submersible pump for irrigation, the larger flow rate can be appropriately selected.