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11. Troubleshooting
11.1 Cause codes
Symptoms
Pump does not deliver any liquid at start-up
Pump stops delivering liquid after start-up
Pump overheats and/or ceases to deliver liquid
Insufficient flow rate
Excessive flow rate
Discharge pressure is too high
Shaft seal leaks appreciably, or the packing leaks
excessively
Shaft seal or packing fails prematurely
Pump uses too much power
Pump runs rough and noisily
11.2 Possible causes
1. The pump has not been properly bled of air.
2. The pump suction line has not been completely primed.
3. The suction head (NPSHR) required by the pump is too high,
or the net positive suction head available (NPSHA) at your
facility is too low.
4. The fluid pumped contains too much entrained air or gas.
5. There are air pockets in the suction line.
6. An entry of air has suddenly occurred in the suction line.
7. An entry of air past the shaft seal into the pump has occurred.
8. The inlet of the suction line is insufficiently submerged.
9. The suction valve is closed or only partially open.
10. The suction strainer is clogged with dirt or debris.
11. The foot valve is clogged or undersized.
12. Little or no cooling fluid supplied to the shaft seals.
13. The lantern ring is not positioned opposite the flushing inlet
thereby restricting fluid flow.
14. Pump drive rotational speed too low.
15. Pump drive rotational speed too high.
16. Pump rotation wrong or impeller installed backwards.
17. Total head of installation (back pressure) higher than rated
total head of the pump.
18. Total head of installation (back pressure) lower than rated
total head of the pump.
19. Density of fluid pumped differs from that specified when the
pump was purchased.
20. Viscosity of fluid pumped differs from that specified when the
pump was purchased.
21. The pump is operating at too low a rate of flow. The discharge
valve may be throttled too much.
22. If pumps are operating in parallel, the pump characteristics
may not be suitable for parallel operation.
23. The impeller may be clogged with debris.
24. The impeller may be damaged.
25. The casing and impeller wear rings may be excessively worn.
26. There may be internal leakage from the discharge to the
suction compartments as the result of internal gasket failure.
27. There may be a misalignment of the pump shaft.
28. The shaft may chatter because it is bent.
29. The pump may run rough due to improper balancing of the
impeller.
30. The shaft may not be running due to worn bearings.
Cause code
1*2*3*4*5*6*7*8*9*10*11*14*16*17*22*23*24*34
2*3*4*5*6*7*8*9*10*11*12*13*22*23*24*34
1*3*9*10*11*21*22*27*29*30*31*33*34*40*41
2*3*4*5*6*7*8*9*10*11*14*16*17*20*21*22*23*24*25*26*34
15*18*20*34
4*14*16*18*20*22*23*24*25*26*34
27*28*29*30*33*34*35*36*39
12*13*27*28*29*30*33*34*35*36*37*38*39
15*16*18*19*20*23*25*27*28*31*33*34*35*37*38
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
31. The impeller may be rubbing against the inside of the case.
32. The concrete pad might not be of sufficient size to provide
pump stability.
33. The pump may have become misaligned during installation.
34. The operating conditions of the installation do not agree with
the data specified when the pump was purchased.
35. The shaft seal may be incorrectly installed, or the stuffing box
has not been packed correctly.
36. The shaft sleeve may be scored or pitted in the region of the
packing due to dirt or abrasive matter in the flushing fluid.
37. Excessive tightening of the packing gland may block the
flushing port thereby diminishing the sealing fluid flow.
38. Packing material may have become wedged or extruded
between the shaft and the bottom of the stuffing housing due
to excessive clearance on the packing backup washer.
39. The mechanical seal may have been damaged by running dry.
40. There may be excessive axial thrust (side loading) due to
improper impeller central alignment.
11
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