Sometimes the water pump cannot pump water during use. So, what are the reasons that affect the water pump not pumping water? Let's talk about it below...
Analysis of the reasons why the water pump does not pump water:
01
There is air in the water inlet pipe and pump body
1) The water pump is not filled with enough water before starting. Sometimes it seems 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 water inlet pipe or pump body.
2) The horizontal section of the water inlet pipe in contact with the water pump uses a descending slope of more than 0.5% against the direction of the water flow, and the end connected to the water pump inlet is the highest. Do not be completely horizontal. If it is tilted upward, air will remain in the water inlet pipe, reducing the vacuum in the water pipe and the water pump, affecting water absorption.
3) The packing of the water pump has been worn due to long-term use or the packing is pressed too loose, causing a large amount of water to spray out from the gap between the packing and the pump shaft sleeve. As a result, the external air enters the inside of the water pump from these gaps, affecting water extraction.
4) The water inlet pipe is submerged underwater for a long time, and the pipe wall corrodes and has holes. After the water pump is working, the water level continues to drop. When these holes are exposed to the water surface, air enters the water inlet pipe through the holes.
5) Cracks appear at the bend of the water inlet pipe, and there is a tiny gap at the connection between the water inlet pipe and the water pump, which may allow air to enter the water inlet pipe.
02
Low speed of water pump
1) Human factors. Some users randomly match another motor to drive the original motor because it is damaged, resulting in small flow, low head, or even no water supply.
2) Mechanical failure of the water pump itself. The impeller and pump shaft fastening nut is loose or the pump shaft is deformed and bent, resulting in multiple impeller movement, direct friction with the pump body, or bearing damage, which may reduce the speed of the water pump.
3) The power machine is not properly repaired. The motor loses magnetism due to winding burnout. Changes in the number of winding turns, wire diameter, and wiring method during maintenance, or failure to completely eliminate faults during maintenance will also cause the pump speed to change.
03
The pump suction is too large
Some water sources are deep, and the outer terrain of some water sources is flat, ignoring the allowable suction of the pump, resulting in less water or no water at all. It should be known that the vacuum that can be established at the suction port of a self-priming centrifugal pump is limited. The suction range of a certain vacuum is about 10 meters high, and the pump cannot establish a certain vacuum.
And if the vacuum is too large, it is easy to vaporize the water in the pump, which is not good for the operation of the pump. Therefore, each centrifugal pump has its maximum allowable suction range, which is generally between 3 and 8.5 meters. When installing a water pump, you must not just seek convenience and simplicity.
04
The resistance loss in the inlet and outlet pipes of the water flow is too large
Some users have measured that although the vertical distance from the reservoir or water tower to the water source is slightly less than the pump head, the water volume is still small or no water can be lifted. The reason is often that the pipeline is too long, there are many bends in the water pipe, and the resistance loss of the water flow 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 the water flow in the pipeline is too large. Under normal circumstances, the resistance of a 90-degree elbow is greater than that of a 120-degree elbow. The head loss of each 90-degree elbow is about 0.5~1 meter, and the resistance of each 20-meter pipeline can cause the head loss to be about 1 meter. In addition, some users also randomly adjust the diameter of the inlet and outlet pipes of the water pump, which also has a certain impact on the head.
05
The impact of other factors
1) The bottom valve cannot be opened. Usually it is because the water pump has been idle for too long, the bottom valve gasket is stuck, and the bottom valve without a gasket may rust.
2) The filter screen of the bottom valve is blocked; or the filter screen is blocked by the sludge layer in the bottom valve.
3) The impeller is severely worn. The impeller blades are worn after long-term use, affecting the performance of the water pump.
4) Faults or blockages in the gate valve or check valve will cause a decrease in flow or even failure to pump water.
5) Leakage in the outlet pipe will also affect the water extraction volume.
