The Water Pump Is Not Pumping Water，what's Going On

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 is not 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 should have a downward slope of more than 0.5% against the direction of the water flow, and the end connected to the water pump inlet should be 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, external air enters the inside of the water pump from these gaps, affecting water lifting.

4) The water inlet pipe has been submerged in water for a long time, and holes appear in the pipe wall due to corrosion. 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 from the holes.

5) Cracks appear at the bend of the water inlet pipe, and a small gap appears at the connection between the water inlet pipe and the water pump, which may allow air to enter the water inlet pipe.

02

Sanitary Volute Pump Low speed

1) Human factors. Some users arbitrarily match another motor to drive the original motor because it is damaged, resulting in low flow, low head or even no water supply.

2) Mechanical failure of the water pump itself. The impeller and pump shaft fastening nut loosens or the pump shaft deforms and bends, causing the impeller to move more, directly rub against the pump body, or bearing damage, which may reduce the speed of the water pump.

3) Ineffective maintenance of the power machine. The motor loses magnetism due to the burning of the winding. Changes in the number of winding turns, wire diameter, and wiring method during maintenance, or factors that are not completely eliminated during maintenance will also cause the speed of the water pump to change.

03

The suction range of the water pump is too large

Some water sources are deep, and the outer terrain of some water sources is relatively flat. The allowable suction range of the water pump is ignored, resulting in less water suction or no water suction 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 an absolute vacuum is about 10 meters of water column height, and it is impossible for a water pump to establish an absolute vacuum.

Moreover, 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 water 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 only 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 surface of 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 water flow in the pipeline is too large. Generally, the resistance of a 90-degree bend is greater than that of a 120-degree bend. The head loss of each 90-degree bend is about 0.5~1 meter, and the resistance of each 20-meter pipeline can cause a head loss of about 1 meter. In addition, some users also arbitrarily adjust the diameter of the inlet and outlet pipes of the water pump, which also has a certain impact on the head.

05

Influence of other factors

1) The bottom valve cannot be opened. Usually, it is because the water pump has been shelved for too long, the bottom valve gasket is stuck, and the bottom valve without a gasket may rust.

2) The bottom valve filter screen is blocked; or the bottom valve is submerged in the sludge layer in the water, causing the filter screen to be blocked.

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 no water to be pumped.

5) Leakage in the outlet pipeline will also affect the water lifting volume.