Reasonable Selection Method For Agricultural Submersible Pumps

Oct 10, 2024

There are many types of submersible pumps, and it is necessary to choose them appropriately according to the actual situation. Based on our experience, we can consider the following three aspects:
1, Selection of main parameters for submersible pumps
(1) Head: refers to the increase in energy per unit weight of liquid pumped by a water pump from the pump inlet to the pump outlet, that is, the height of the liquid column pumped by the pump. Represented by H, the unit is m. It should be noted that when a submersible pump is used to lift well water, the HD value is determined based on the lowest point where the water level in the well may drop; In addition, long pipelines, multiple bends, and rough pipe walls can reduce water pressure and increase head loss HL. Based on our experience, the value of HL is generally considered as 10% of the pipeline length. After determining the head H2N according to the above formula, we suggest increasing the head margin by 5% to avoid insufficient head during actual use. But don't add too much and cause waste.
(2) Flow rate: refers to the amount of liquid pumped out by a water pump per unit time. Expressed as Q, the unit is m ³/h. There are two points to note when selecting the flow rate of a submersible pump: firstly, the flow rate of the submersible pump running in the well water should be less than or equal to the water inflow in the well. Otherwise, it will drain the water in the well and cause the motor to burn out; Secondly, the actual working flow rate of the submersible pump should be between 0.7 and 1.2 times the rated flow rate of the pump. Because the efficiency of the pump is higher within this flow range.
2, Selection of structural types for submersible pumps
(1) According to the structural type of the water pump motor, there are dry, oil immersed, water filled, and shielded types. Dry type motors, like ordinary enclosed motors, have the stator and rotor in the air; The oil immersed motor is filled with oil inside; The interior of the water filled motor is filled with clean water; The stator and rotor of a shielded motor are separated, with the stator part being dry and the rotor part being filled with oil or water.
The sealing performance of dry-type motors is relatively poor, but they are inexpensive; Oil immersed motors and water filled motors can improve sealing conditions, making it difficult for external water to enter the interior of the motor, and have a wide range of applications; Shielded motors have good sealing and insulation performance, and are also relatively expensive.
(2) According to the structural type of the water pump itself, there are axial flow, centrifugal, mixed flow, etc., each suitable for different occasions. Axial flow water pumps are suitable for low head and high flow situations; Centrifugal water pumps are suitable for high head and low flow situations; Mixed flow water pumps are suitable for situations where the head and flow rate are relatively moderate.
We only need to follow the above two aspects and combine them with the specific situation of the actual application to make an appropriate choice for the structural type of submersible pump.
3, Selection of outlet piping for submersible pumps
Various specifications of submersible pumps have certain requirements for the outlet pipe. Inconsistent inner diameter or excessively long length can affect flow rate, reduce efficiency, and waste electrical energy. At the same time, it also consumes the head of the pump, which cannot meet the requirements for the use of submersible pumps. Therefore, it is necessary to select the outlet pipe according to the inner diameter requirements of the pump for the outlet pipe, and its length should be determined based on the principle of the minimum length that reaches the head height. If replacement is needed due to issues such as a shortage of water supply in the outlet pipe, the flow velocity of the water in the substitute pipe should generally be controlled below 4m/s.