The causes and treatment methods of mechanical seal damage in centrifugal pumps

The following are six reasons for centrifugal pump seal damage, with specific details 

and solutions for each:

1. Poor water quality, containing particles. Poor water quality, including small particles 

and high hydrochloric acid content in the medium, causes abrasive wear on the mechanical

 seal, resulting in grooves or ring grooves on the surface. Solution: Improve water pressure 

or medium; replace the mechanical seal.

2. Cavitation. Cavitation (mainly occurs in hot centrifugal pumps). Because the medium is 

hot water, excessively high water temperature generates steam. Gas from the pipeline enters

 the pump chamber at a high point, unable to escape, leading to water shortage operation,

 dry running of the mechanical seal, and cavitation failure. Solution: Replace the mechanical seal.

3. Dry running damage due to water shortage. This phenomenon is often seen in pump 

installations with negative pressure at the inlet, air in the inlet pipe, and air in the pump chamber.

 After the pump starts, the mechanical seal generates high temperatures due to high-speed friction, 

which cannot be cooled. Inspection of the mechanical seal reveals normal spring tension, but the 

friction surface is charred and blackened, and the rubber is hardened and cracked. Troubleshooting:

**1.** Air in the pipeline and pump chamber; replace the mechanical seal.

**2.** Overly Tight Installation: Observe the dynamic and static ring surfaces of the mechanical seal. 

If there is severe burning, the surface is blackened with deep marks, and the sealing rubber is hardened 

and has lost its elasticity, this is caused by over-tight installation. Solution: Adjust the installation height. 

After installing the impeller, use a screwdriver to move the spring. The spring should have strong tension 

and return to its original position after loosening, with a movement distance of 2-4mm.

**3.** Water Leakage at the Mechanical Seal: Solution: Fill the leakage gap with high-density material or 

replace the mechanical seal.

**4.** Loose Installation: Observe the dynamic and static ring surfaces of the mechanical seal. A thin 

layer of scale on the surface can be wiped away, and the surface is basically unworn. This is caused by

 the spring losing its elasticity, improper assembly, or axial movement of the motor. Solution: Replace 

the spring and motor shaft, and reassemble.