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How to Select a Deep Well Pump(Part 2)?

Aug. 29, 2020

1. According to the water output of the well, select the flow rate of the well pump

Each well has an economically optimal water output, and the flow rate of the water pump should be equal to or less than the water output when the water level of the pumped well drops to half the depth of the well. When the pumping water is greater than the pumping water from the engine well, it will cause the wall of the pumped well to collapse and deposit, which will affect the life of the well; if the pumping volume is too small, the benefits of the well will not be fully utilized. Therefore, the best way is to conduct pumping tests on pumped wells, and select the pump flow rate based on the maximum possible water output from the well. The flow rate of the pump is subject to the manufacturer's model or the number marked in the manual.

2. Pumped wells with sand content of well water exceeding one ten thousandths should not be installed with deep well pumps

Because the sand content of the well water is too large, if it exceeds 0.1%, it will accelerate the wear of the rubber bearings, cause the pump to vibrate, and shorten the pump life.

Deep Well Pump

3. Initially determine the pump type according to the well diameter and water quality

Different types of pumps have certain requirements on the diameter of the well bore, and the maximum external size of the pump should be less than 25-50 mm in the well diameter. If the borehole is skewed, the maximum size of the pump should be smaller. In short, the pump body cannot be close to the inner wall of the well to prevent pump vibration from damaging the well.

4. Determine the actual required lift of the well pump according to the depth of the well water level drop and the head loss of the water pipeline

The head actually required by the well pump, that is, the head of the well pump, is equal to the vertical distance (net head) from the water level to the water surface of the outlet pool plus the loss head. The loss head is usually 6-9% of the net head, generally 1~2m.

The water entry depth of the bottom stage impeller of the pump is preferably 1~1.5m. The total length of the downhole part of the pump tubing should not exceed the maximum length of entry into the well specified in the pump manual.

If a high-lift pump is used for low-lift pumping, its flow will inevitably increase. Even outside the working range, running under conditions of large flow, low efficiency, and high energy consumption, it seems that the pumping speed can be accelerated on the surface. Improve the pumping efficiency, but the gain is not worth the loss. It is not recommended, because when the flow rate of the pump reaches or exceeds the maximum extraction rate of the well, the structure of the filter layer outside the well pipe will be destroyed. The ground nearby will sink, which will endanger the safety of the well. In addition, if the pump runs at high lift, large flow, low efficiency, and high speed for a long time, the pump's inlet flow rate will increase, which will destroy the chemical balance of the groundwater and cause the dissolved substances in the water to precipitate and settle in the inlet gap or pit of the filter tube. , Accelerating fouling, leading to clogging of the filter screen, and with time the clogging continues to increase, the water pump will be damaged by corrosion and cavitation in advance, and lead to increased consumption and electricity bills. Therefore, the head of the deep well pump must be equal to or slightly greater than the total pressure head loss consumed in the water delivery process.

The information is provided by deep well pump manufacturers.


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