What Is The Problem Of Multi-stage Centrifugal Pump Not Producing Water During Operation

Oct 29, 2025

What is the reason for the sudden failure of multi-stage centrifugal pumps to produce water during operation?

Let's find the root cause of why multi-stage centrifugal pumps do not produce water during operation from these eight places.

(1) Cracks at the bend of the inlet pipe and small gaps at the connection between the inlet pipe and the water pump may allow air to enter the inlet pipe.

(2) The inlet pipe has holes due to long-term potential underwater corrosion of the pipe wall. After the multi-stage centrifugal pump works, the water level continuously drops. When these holes are exposed to the water surface, air enters the inlet pipe through the holes.

(3) The horizontal section of the inlet pipe in contact with the multi-stage centrifugal pump should have a descending slope of 0.5 or more in the opposite direction of the water flow. The end connected to the inlet of the water pump should be the highest 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.

(4) Before starting the multi-stage centrifugal 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.

 

 

(5) Mechanical failure of the centrifugal pump itself. Loosening of the fastening nut between the impeller and the pump shaft or deformation and bending of the pump shaft can cause excessive movement of the impeller, direct friction with the pump body, or damage to the bearings, all of which may reduce the speed of the water pump.

(6) The packing of a multi-stage centrifugal 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.

(7) The maintenance of the power machine is not working properly. The motor loses magnetism due to burnt windings, 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.

(8) Human factors. Some users, due to damage to the original motor, randomly installed another motor to drive it, resulting in low flow rate, low head, and even no water supply.