Several Common Causes Of Water Pump Leakage And Their Solutions

Mar 04, 2022

Mechanical seal is the main cause of water pump leakage, but mechanical seal itself is a precision component with high requirements, which has high requirements for design, machining and assembly quality. When using the mechanical seal, various factors of using the mechanical seal shall be analyzed to make the mechanical seal suitable for the technical requirements and service medium requirements of various pumps and have sufficient lubrication conditions, so as to ensure the long-term and reliable operation of the seal.

The mechanical seal, also known as the end seal, has a pair of end faces perpendicular to the rotation axis. Under the action of fluid pressure and compensating the external elastic force of the machine, the end face keeps fit with the other end and slides relative to the other end depending on the cooperation of the auxiliary seal, so as to prevent fluid leakage.

 Common leakage

The leakage of mechanical seal accounts for more than 50% of all maintenance pumps. The operation of mechanical seal directly affects the normal operation of water pump. The summary and analysis are as follows.

1.Periodic leakage

(1) The axial displacement of the pump rotor is large, the interference between the auxiliary seal and the shaft is large, and the moving ring cannot move flexibly on the shaft. After the pump is overturned and the dynamic and static rings are worn, the displacement cannot be compensated.

Countermeasures: when assembling the mechanical seal, the axial displacement of the shaft should be less than 0.1mm, and the interference between the auxiliary seal and the shaft should be moderate. While ensuring the radial seal, the movable ring can move flexibly on the shaft after assembly (press the movable ring towards the spring and spring back freely).

(2) Insufficient lubricating oil on the sealing surface causes dry friction or roughening of the sealing face.

Countermeasures: the height of lubricating oil level in the oil chamber shall be higher than the sealing surface of dynamic and static rings.

(3) The rotor vibrates periodically. The reason is that the stator is not aligned with the upper and lower covers, or the impeller and main shaft are unbalanced, cavitation or bearing damage (wear), which will shorten the sealing life and produce leakage.