RDL
11. Trouble shooting
Fault Possible causes
Pump fails to deliver liquid after being switched on
1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 14, 16, 17, 22, 23, 24,
34, 39
Pump ceases to deliver liquid 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 22, 23, 24, 34, 39
Pump overheat and/or fails to deliver liquid 1, 3, 9, 10, 11, 21, 22, 27, 29, 30, 31, 33, 34, 40, 41
Flow capacity too low
2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 14, 16, 17, 20, 21, 22,
23, 24, 25, 26, 34
Flow capacity too high 15, 18, 20, 34
Pump pressure too low 4, 14, 16, 18, 20, 22, 23, 24, 25, 26, 34
Excessive leakage at shaft seal 27, 28, 29, 30, 33, 34, 35, 36, 38, 39, 41
Excessive wear on gaskets 12, 13, 27, 28, 29, 30, 33, 34, 35, 36, 37, 38, 39, 41
Drive machine overload
12, 13, 15, 18, 19, 20, 23, 25, 27, 28, 31, 33, 34, 35,
37, 44
Pump does not run smooth (noise)
2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 15, 17, 18, 21, 23, 24, 27,
28, 29, 30, 31, 32, 33, 34, 40, 41, 42, 45, 46
Bearings temperature too high 27, 28, 29, 30, 31, 32, 33, 34, 40, 41, 42, 43, 44, 45, 46
Table 6 – Faults and possible causes
Probable Causes
1. Pump was not appropriately primed.
2. Pump and suction piping are not totally filled with liquid to be
pumped.
3. Suction is too high, that means NPSHr is higher than
NPSHd.
4. Pumped liquid contain air or gas.
5. Air pocket in the suction piping.
6. Air entrance in the suction piping.
7. Air entrance through shaft sealing.
8. Suction piping is not enough submerged.
9. Suction valve is closed or partially opened.
10. Foot valve or strainer of suction piping is dirty, or clogged.
11. Foot valve is too small or it is clogged.
12. None, or insufficient quantity of sealing / lubricating liquid in
the shaft seal housing.
13. Lantern ring is not located according to the designed, below
the sealing liquid hole, this way the shaft seal chamber is
irregularly feed by insufficient quantity of sealing / lubricating
liquid.
14. Too low speed.
15. Too high speed.
16. Speed in reverse side.
17. Total installation height (counter pressure) higher than head.
18. Total installation height (counter pressure) lower than head.
19. Liquid specific gravity is different from specified.
20. Liquid viscosity is different from specified.
21. Pump functioning with too low flow (discharge of valve piping
probably partially closed).
22. Parallel operation with different hydraulic characteristics.
23. Foreign particles in the impeller.
24. Defective or worn impeller.
25. Casing and/or impeller wear rings worn.
26. Pump internal leakage from pressure chamber to the suction,
due to worn wear rings.
27. Misalignment of coupling.
28. Shaft vibration.
29. Shaft vibration due to absence of rotor balance.
30. Shaft runs eccentric due to wear of bearings or misalignment.
31. Impeller friction with casing parts.
32. Foundation is not rigid enough.
33. Pump is not aligned.
34. Operation conditions are not according to the indicated data
of the Purchase order.
35. Incorrect assembly of shaft seal or mechanical seal.
36. Wear of shaft protective sleeve, due to abrasive solids of the
sealing liquid.
37. Insufficient packing lubrication, due to gland cover being over
tightened.
38. Excessive clearance between shaft and neck ring, or
between shaft and shaft passage diameter in the seal
chamber.
39. Damaged mechanical seal due to dry operation.
40. High axial thrust, due to defect inside the pump.
41. Worn bearings.
42. Defective assembly of bearings.
43. Excessive quantity of grease in the bearing housing.
44. Defective lubrication of the bearings.
45. Dirty bearings.
46. Oxidation of bearings due to water or moisture in bearing
housings.
KSB has the right to change any information contained in this manual without previous notice.
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