9. Flushing or circulation line blocked
10. Lantern ring incorrectly located
11. Speed too low
12. Speed too high
13. Incorrect direction of rotation
14. Total head of the system greater than specified
15. Total head than specified
16. Specific gravity of liquid different from specified value
17. Actual viscosity differs from specified value
18. Operation at too low capacity
19. Pumps are unsuitable for parallel operation
20. Strainer blocked
21. Actual temperature of fluid differs from specified value
22. Too fast temperature changes
Mechanical reasons
1.
Foreign bodies in the impeller
2. Incorrect alignment
3. Foundation block too weak
4. Bent shaft
5. Rubbing of rotating parts on fixed parts
6. Worn bearings
7. Worn wear rings, distance sleeves and throat bushes
8. Wrong design of suction line, leading to asymmetrical flow or vortexing
9. Impeller damaged
10. Shaft sleeve worn
11. Incorrectly installed packing
12. Incorrect packing type installed
13. Non concentric running of rotor due to bearing wear or incorrect alignment
14. Rotor not properly balanced
15. Stuffing box pulled up too tightly
16. Insufficient cooling
17.
Dirt or grit in sealing, flushing or circulating fluids
18. Excessive thrust
19. Excessive oil in bearing housing, blocking oil passages
20. Defective lubrication
21. Bearings incorrectly installed or damaged during installation
22. Dirt in bearings or lubrication system
23. Access of water into the bearings
24. Difficulties arising from the pump driver
