Tips for buying centrifugal pumpsHere are some important tips while buying a centrifugal pump.Pump SelectionAvoid over sizing of your pumps as this results in uneconomical operation ofthe pump. It also narrows the safe operation range of capacities of the pump.Avoid pumps with a really low NPSH (Net Positive Suction Head) andremember not to falsify the actual NPSH. Resorting to this leads to choosing ofpumps with excessively high suction speeds and high minimum flows.Evaluating the advantage of variable speed operation will be useful as it isefficient and results in longer pump life. Be careful not use a mechanical sealwhen packing is more than adequate for the intended use.InstallationEnsure adequate submergence over intake piping to prevent formation ofvortex. Suction elbows should always be placed over the in the planeperpendicular to the shaft and not parallel. Pump casing should not be used asan anchor for the pump. All expansion joints and supports should be anchoredindependently. Providing adequate flow, pressure and temperatureinstrumentation for the pump are imperative. Pump and driver alignment haveto be rechecked under normal operating conditions.OperationEnsure you do not operate pumps below the recommended minimum flow orwhen suction valve is closed. Ensure you do not run two pumps parallel whenone pump can carry the load. Make sure that air is kept out of the pump,pumps are made to carry liquids only. Stop the pump immediately is anyexcessive noise or vibration occurs. Run spare pumps once in a while to checktheir efficacy.MaintenanceRunning performance test at frequent intervals will help you to followincreased internal clearances. Avoid opening of pumps unless any evidenceproves it necessary. Lubricating or greasing of lubricated bearings are notnecessary, avoid doing that. Packing stuffing boxes needs experienced hands,leaving it to inexperienced hands will prove detrimental. Avoid tighteningstuffing box glands too much. Leakage needs to flow smoothly to cool andlubricate properly. Always use original spares excepting in an emergency.Examine and recondition your pump regularly. Look out for corrosion in yourpumps. Always new gaskets in your pumps when overhauling them.
Follow these steps and your centrifugal pump will serve you well for years.