A deep well pump is a vertical multistage centrifugal pump that lifts water from deep wells. The use of deep well pumps is more widely used than general centrifugal pumps with the decline of the groundwater level. However, due to the improper choice of the pump, some users have caused problems such as insufficient water output, failure to pump water, and even damage the well. So, how should we choose a deep well pump?
1) Choose the deep well pump according to the maximum allowable water volume of the water well. The flow rate of the pump must be in line with the actual amount of water in the well, the flow rate must be equal to or slightly less than the actual amount of water extraction in the well, otherwise it is bound to produce a strong pumping situation, this will not only shorten the service life of the deep well pump but also seriously destroy the filter, causing more than sand, and even cause the well to be scrapped.
2) The diameter of the deep well pump must be in line with the diameter of the well body. In order to be able to be smoothly put down and take out the deep well pump, pumping when the groundwater has space to quickly gather, less affected by resistance and can also reduce the operation of the pump wear and tear, the requirements of the lifting pipe and pump body parts of the well body diameter should be greater than the maximum diameter of the pump body by 20 ~ 40 mm, that is, the maximum diameter of the pump body parts and well wall between the ring gap should be at least 10 ~ 20 mm so as to extend the service life of the well and deep well pump.
3) The location of the deep well pump should never be in the location of the filter pipe but in the well wall pipe location, otherwise the pump will pump water with a lot of sand or even destroyed the well. The well structure (well diameter, filter pipe, well wall pipe location) and well depth and pump selection should be decided based on the hydrogeological conditions of the well and neighboring wells (depth of the aquifer, aquifer thickness, aquifer lithology) and pump operation to ensure that no problems occur in the future during pumping and pump operation.
4) Determine the specification and model of the deep well pump according to the amount of water gushing from the well.
5) Choose a deep well pump according to the total head loss. The diameter, head (number of stages) and power of the deep well pump are selected according to the total head loss required to lift the groundwater from the pump head to the surface pool or water tower. The water pressure increases proportionally with the number of impellers flowing through it. The impeller of a deep-well pump is submerged in water and has only head and no suction range. The difference between the rated head and the actual operating head of the pump must not be too great (never more than 25% of the actual head). High pump head and required motor power is easy to cause the pump to have a larger string, which will damage the impeller and leaf casing, even in the shell of the bearing will also be easy to stick with the pump coupling and cause the pump can not run, and then the motor overload winding will burn out.
1. The flow rate of the well pump is selected according to the volume of water coming out of the well.
Each well has an economically optimal water output. The flow rate of the pump should be equal to or less than the water output when the water level of the well drops to half the depth of the well. When the pumping capacity is greater than the well output, it can cause the well wall to collapse and silt up, affecting the life of the well; If the pumping capacity is too small, the benefits of the well will not be fully utilized. Therefore, the best approach is to carry out a pumping test on the well and use the maximum amount of water that the well can provide as the basis for selecting the pump flow rate.
2. Deep well pumps should not be installed in wells with a sand content of more than 1 in 10,000.
This is because if the sand content of the well water is too high, it will accelerate the wear of the rubber bearings, cause the pump to vibrate and shorten the life of the pump.
3. The pump type is initially selected according to the well diameter and water quality.
Different types of pumps have certain requirements on the size of the well hole diameter, the maximum size of the pump should be smaller than the well diameter 25-50 mm. If the well hole is skewed, the maximum size of the pump should even be smaller. In short, the pump body part should not be close to the inner wall of the well to prevent the well from being damaged by pump vibration.
4. Determine the actual head required for the well pump based on the depth of drop in the well water level and the head loss in the transmission line.
The actual head required by the well pump is equal to the vertical distance from the water level to the water surface of the outlet pool (net head) plus the loss of head. The loss of head is usually 6% to 9% of the net head, generally 1 to 2m.
The depth of entry of the impeller at the lowest level of the pump should be 1m to 1.5m.
If a high head pump is used for low head pumping, its flow rate is bound to increase. However, if the pump is operated outside its operating range at high flow rates, low efficiency and high energy consumption, it may seem on the surface to speed up pumping and improve pumping efficiency, but in fact this practice will not pay off, because when the flow rate of the pump reaches or exceeds the maximum extraction capacity of the well, the structure of the filter layer on the outside of the well pipe will be damaged, a large amount of sand will enter the well, and even the ground near the wellhead will sink, which will endanger the safety of the well. In addition, if the pump runs at high speed for a long time at high head, high flow rate and low efficiency, the flow rate of the incoming water from the pump will be accelerated, which will destroy the chemical balance of the groundwater and cause the dissolved substances in the water to precipitate in the incoming slits of the filter pipe and accelerate the scaling, which will lead to the blockage of the filter. And as the blockage continues to intensify, the pump will be corroded and cavitation and over damage, and lead to consumption and electricity expenses increased. Therefore, the head of the selected deep well pump must be equal to or slightly greater than the total loss of head consumed in the water delivery process.