| No fluid is delivered | Pump is not primedSpeed is too lowRequired discharge head is too high compared to pump designSuction line or strainer is cloggedImpeller is completely clogged Wrong pump rotation direction / motor wired wrongToo much clearance between impeller and intake flange |
| Not enough fluid is delivered | Air leaks in suction or stuffing boxesSpeed is too lowRequired discharge head is greater than anticipatedToo much clearance between impeller and intake flangeImpeller is partially cloggedMechanical defects such as a worn impeller wear ring or damaged impeller.Impeller diameter is too smallFoot valve at end of suction line is too small, allowing fluid to exit and compromising prime.Foot valve or suction opening are not submerged deep enough. NPSHr > NPSHa |
| Not enough pressure | Speed too lowAir entrained in the fluidMechanical defects such as worn impeller ring or damaged impellerImpeller diameter too smallPump producing too much flow, insufficient back-pressure |
| Vibration / Noise | Bent shaftPipe strainImpeller clogged, causing imbalanceMotor – pump coupling misalignmentPump is not fully secured to its mounting baseMotor and/or pump bearings are going badPump is cavitating – insufficient fluid level |
| Pump takes too much power | Speed is too highActual head is lower than its rating, pumping too much fluidSpecific gravity or viscosity of fluid is too high and/or weren’t taken into account when the pump and motor were sized.Mechanical defects such as bent shaft, power frame in a bind, worn impeller wear ring. |
| Stuffing box is leaking – mechanical seal failure | Over time, this is normal. Mechanical seals will fail eventually. They are more prone to failure when incorrect seal faces are used given the composition of the fluid pumped, when seals are not properly flushed, when the pump runs dry, |
| Bearings are running hot | Improper lubrication – use of incompatible lubricant, too infrequent lubrication, or over-lubricationLube cooling (outside service?)Improper pump and motor alignment |
| Pump starts to pump then ceases | Improper pump primingAir leak in suction lineAir or vapor pocket accumulation |
