The stainless steel multi-stage pump has been working for a long time. Due to the Causes such as loose water seal, air in the pump body, motor reversal, impeller flow channel blockage, etc., the water pump suction is insufficient, which greatly affects the production efficiency of the water pump. Our factory has summarized the Causes and solutions for the insufficient suction of the stainless steel multi-stage pump. The following is a detailed introduction.

1. Motor reverse

Cause: The motor rotor and stator are worn, the three-phase motor is missing a phase or is unbalanced, and the power cord wiring sequence is incorrect , resulting in insufficient suction of the water pump.

Solution:

① Check the wear of the motor rotor and stator, replace worn parts in time, and ensure the internal structure of the motor is normal;

② Use a multimeter to check the circuit on/off status and three-phase current balance according to the motor control circuit diagram, accurately locate the fault point of phase loss or current imbalance, and replace the faulty component;

③ If it is confirmed that the fault is caused by the reverse connection of the power cord, you can freely swap the two phase wires on the motor power terminal in the power off state to correct the direction of motor operation.

2. No water is added to the pump chamber

Cause: Before starting the water pump, water was not immediately filled in the pump to completely discharge the air inside the pump body. The pump chamber was unable to form an effective negative pressure, resulting in insufficient suction of the water pump and even "idling" phenomenon.

Solution :

① Before starting the water pump, close the pump outlet valve to prevent water from leaking out of the outlet during filling, and open the exhaust valve on the top of the pump body;

② Slowly inject clean water into the pump chamber until a continuous flow of water overflows from the exhaust valve, then close the exhaust valve and the water inlet;

③ After confirming that the pump chamber is completely filled with water and is in a vacuum state, start the water pump. After the water pump runs stably, gradually open the outlet valve to ensure that the water suction process is normal;

④ If the pump body is equipped with an automatic water priming device, it is necessary to check in advance whether the device is intact to ensure that it can automatically complete the priming and exhaust operations to avoid omissions in manual operations.

3. Leakage in the inlet pipeline

Cause: The inlet pipe is not sealed well and the O-ring inside the sleeve is damaged, resulting in continuous infiltration of air. The pump chamber cannot form sufficient vacuum, which is manifested as a decrease in net suction head and flow attenuation .

Solution: promptly block or repair the leaking part of the inlet pipe, replace the O-ring, or replace the inlet pipe.

4.The import pipeline is too long or too large

Cause: The diameter of the inlet pipe is too wide, the pipe is too long , and the pipe resistance loss is relatively large , resulting in insufficient suction.

Solution: Adjust the installation height of the water pump, reduce the elbow valves in the water inlet pipe, shorten the pipe length, and install the appropriate inlet pipe length.

5. Water seal leakage

Cause: Improper selection of water seal materials; water seal friction damage, unqualified water quality damages the water seal working surface, water seal leakage and insufficient suction.

Solution: Disassemble the water seal to check for defects, perform appropriate repairs and maintenance, and replace it with a new, suitable water seal in a timely manner if the defects are serious.

6. The impeller is not installed in place

Cause:

①　The installation operation was not careful enough, resulting in the impeller not fitting tightly against the relevant components.

②　The impeller is installed in the wrong direction. Reverse installation will affect the suction performance of the pump.

Solution:

①　Reinstall the impeller correctly according to standard procedures.

②　After installation, check the impeller surface smoothness.

③　Ensure that the clearance between the impeller and other components meets the equipment operation requirements.

④ 　Verify that the impeller is rotating correctly.

7. The screws are not tightened

Cause: The water pump vibrates during long-term operation, causing the screws to gradually loosen. Or the screws were not tightened tightly when tightened manually.

Solution: We need to check the tightness of the screws regularly. Once any looseness is found, tighten the screws immediately to prevent them from falling off.

8. Impeller flow channel is blocked

Cause: Scale deposits form inside the impeller, blocking the blade gap and hindering the rotation of the impeller, which eventually leads to a decrease in the suction volume in the pump and a decrease in suction force.

Solution: Clear the filter screen and filter at the water inlet section, and the sediment inside the pump and pipes to ensure that the water pump can deliver water smoothly.

9. Large gap between impeller and side cover

Cause: The gap between the impeller and the side cover exceeds the specified range, and external air enters the pump body through the gap, destroying the vacuum environment inside the pump and causing insufficient suction.

Solution: According to the specific value of wear, subtract the excess paper pad between the pump body and the side cover, and adjust the gap to the specified value in time.

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