Mechanical seals rarely fail on their own. In most pumps we inspect, the seal is the first part to show a problem that started somewhere else.
Running dry
A seal needs liquid between its faces to cool and lubricate them. A few seconds of dry running can crack carbon or ceramic faces. Air locks after maintenance and low suction tank levels are common causes.
Misalignment and vibration
When the pump and motor shafts are not aligned, the seal faces move on every revolution. Worn bearings and an unbalanced impeller have the same effect.
The wrong seal for the liquid
Abrasive solids, chemicals and hot water each need suitable face materials and elastomers. A standard seal on slurry or chemical duty will wear out quickly.
Cavitation
When NPSH available is too low, vapour bubbles form and collapse near the impeller. The vibration and heat reach the seal.
Rule of thumb
If seals keep failing at the same interval, look at the operating point and the installation before ordering the next seal.
Conclusion
Send us the pump model, the liquid and the failure history. We can recommend the right seal and check whether the pump is running near its best efficiency point.
