Bell & Gossett P5002169C Series VSCS - Manual (Page 24)

22
CAUSES CURES
Not Enough Pressure
20. Mechanical defects See items 14 and 15.
21. Obstruction in liquid passages Dismantle pump and inspect passages of impeller and casing.
Remove obstruction.
22. Air or gases in liquid Install an air removal device or repair leaks in system piping.
23. Too small impeller diameter
(Probable cause if none above) See item 17.
24. Speed too low See item 5.
25. Excessive system flow Balance system.
Pump Operates For Short Time, Then Stops
26. Incomplete priming Free pump, piping and valves of all air. If high points in suction line
prevent this, they need correcting.
27. Suction lift too high See item 3.
28. Air leaks in suction piping See item 8.
29. Air or gases in liquid See item 22.
Pump Takes Too Much Power
30. Head lower than rating;
thereby pumping too much liquid. Machine impeller’s OD to size advised by factory.
31. Cavitation See item 13.
32. Mechanical defects. See items 14 and 15.
33. Liquid heavier (in either
viscosity or specific gravity) than
allowed for. Use larger driver. Consult factory for recommended size. Test liquid
for viscosity and specific gravity.
34. Wrong direction of rotation. See item 15.
35. Casing distorted by excessive
strains from suction or discharge
piping. Check alignment. Examine pump for friction between impeller and
casing. Replace damaged parts.
36. Shaft bent due to damage –
through shipment, operation, or
overhaul. Check deflection of rotor by turning on bearing journals. Total
indicator run-out should not exceed 0.002” on shaft and 0.004” on
impeller eye outer diameter.
37. Mechanical failure of critical
pump parts. Check bearings and impeller for damage. Any irregularity in these
parts will cause a drag on shaft.
38. Misalignment. Realign pump and driver.
39. Speed may be too high Check frequency setting on the drive if equipped. Verify that the
driver speed matches the pump nameplate speed.