The speed of the sewage lift pump is too low
1. Human factors; Some users, due to damage to the original motor, randomly installed another motor to drive it, resulting in low water pump flow, low head, or even no water supply;
2. Mechanical failure of the water pump itself; Loose fastening nuts between the impeller and pump shaft or deformation and bending of the pump shaft can cause the impeller to move, resulting in direct friction with the pump body, or damage to the bearings, which may reduce the speed of the water pump;
3. Power machine maintenance is ineffective; The motor may lose magnetism due to winding burnout, and changes in winding turns, wire diameter, and wiring methods during maintenance, or incomplete troubleshooting during maintenance, can also cause changes in the speed of the water pump.
The sewage lift pump does not discharge water and there is air in the inlet pipe and pump body
1. Before starting the sewage pump, it is not filled with enough water. Sometimes it appears that the water has overflowed from the vent hole, but the pump shaft has not been rotated to completely discharge the air, resulting in a small amount of air remaining in the inlet pipe or pump body;
2. The horizontal section of the inlet pipe in contact with the water pump should have a descending slope of at least 0.5% against the direction of water flow. The end connected to the inlet of the water pump should be high and not completely horizontal. If lifted upwards, air will remain in the inlet pipe, reducing the vacuum level in the water pipe and pump, and affecting water absorption;
3. The packing of the water pump has worn out or become too loose due to long-term use, causing a large amount of water to spray out from the gap between the packing and the pump shaft sleeve. As a result, external air enters the interior of the water pump through these gaps, affecting water lifting;
4. The inlet pipe has holes due to long-term potential underwater corrosion on the pipe wall. After the water pump works, the water level continuously drops. When these holes are exposed to the water surface, air enters the inlet pipe through the holes;
5. Cracks at the bend of the inlet pipe and smiling gaps at the connection between the inlet pipe and the water pump may allow air to enter the inlet pipe.
The suction distance is too large
Some water sources are deep, and the surrounding terrain of some water sources is relatively flat, ignoring the allowable suction range of the water pump, which can result in less or no water absorption. The vacuum degree that can be established at the suction port of the water pump is limited, and the suction range of absolute vacuum is about 10m water column high, while the water pump cannot establish absolute vacuum. Moreover, excessive vacuum can cause the water inside the pump to vaporize, which is detrimental to the operation of the water pump. So each centrifugal pump has its maximum allowable suction stroke, usually between 3-8.5m. When installing a water pump, avoid only considering convenience and simplicity.
Excessive resistance loss in the inlet and outlet pipes of water flow
Some users have measured that although the vertical distance from the reservoir or water tower to the water source surface is slightly smaller than the pump head, the water lifting capacity is still small or the resistance loss in the pipeline is too large. The reason is often that the pipeline is too long, there are many bends in the water pipe, and the resistance loss of water flow in the pipeline is too large. In general, the resistance of a 90 degree bend is greater than that of a 120 degree bend, with a head loss of about 0.5-1m per 90 degree bend. The resistance of every 20m pipe can result in a head loss of about 1m.
The influence of other factors
1. The bottom valve cannot be opened; Usually, it is due to the water pump being left idle for too long, causing the gasket of the bottom valve to stick to it. Bottom valves without gaskets may rust and die;
2. The bottom valve filter is blocked; Possible blockage of the filter screen in the sludge layer in the water or bottom valve
3. The impeller is severely worn; The wear and tear of impeller blades over long-term use has affected the performance of the water pump;
4. Malfunctions or blockages in gate valves or check valves can cause a decrease in flow rate or even prevent water from being pumped out;
5. Leakage in the outlet pipeline can also affect the amount of water extracted.
