Selection of self-priming pumps
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For wastewater transfer, the owner has chosen a self-priming pump. The pump is located in the water pumping room; the distance from the wastewater tank to the pumping room is about 20 meters. The inlet pipeline leads from the wastewater tank, which is 5 meters underground, through at least 3 bends, while the outlet pipeline also goes through at least 3 bends before reaching the aeration tank beside the wastewater tank. The flow rate required is 100 m3/h. How should this self-priming pump be selected?
This is very difficult; generally, self-priming pumps can only lift water up to five or six meters, so it’s better to use a portable pump
The pipeline is too long, resulting in high resistance; it may be impossible to draw up the liquid. Installing a water pump near the pool seems unreasonable when a self-priming pump is used.
If a 6\" pipe is used at the inlet, the pressure loss in the pipeline is approximately 0.5 m. Adding the 5 m depth, the suction head at the inlet = 0.5 + 5 = 5.5, or say 6 m. A better self-priming pump can achieve a self-priming depth of up to 8 meters. However, there are still some risks in actual operation. With a conservative design, an automatic water injection system can be installed on the suction pipeline.
Sealless automatic control self-priming pumps or submersible pumps can be used
Choose a submersible pump. The pump doesn’t need to be placed as far away in the pump room; it can be located directly under the liquid surface, which also means it won’t take up much space.