Excessive pump maintenance can indicate:
●pumps are cavitating
●badly worn pumps
●pumps that are not suitable for the operation.
●Pumps throttled at a constant head and flow indicate excess capacity. The pressure drop across a control valve represents wasted energy, which is proportional to the pressure drop and flow.
A noisy pump generally indicates cavitation from heavy throttling or excess flow. Noisy control valves or bypass valves usually mean a high pressure drop with a correspondingly high energy loss.
Pump performance and efficiency deteriorates over time. Pump capacity and efficiency are reduced as internal leakage increases due to excessive clearances between worn p ump components: backplate; impeller; throat bushings; rings; sleeve bearings. A monitoring test can detect this condition and help size a smaller impeller, either new, or by machining the initial one, t o achieve a huge reduction in energy. Internal clearances should be restored if performance changes significantly.
Applying coatings to the pump, will reduce friction losses.
The applicability of particular measures, and the extent of cost savings depend upon the size and specific nature of the installation and system. Only an assessment of a system and the installation needs can determine which measures provide the correct cost-benefit. This could be done by a qualified pumping system service provider or by qualified in-house engineering staff.
The assessment conclusions will identify the measures that are applicable to a system, and will include an estimate of the savings, the cost of the measure, as well as the payback time.
Pumping systems often have a lifespan of 15 to 20 years, so a consideration of lifetime costs against initial (purchase) costs are important.
Pumps are typically purchased as individual components, although they provide a service only when operating as part of the system, so a consideration of the system is important to enable a proper assessment of the cost-benefit.
Energy Efficiency (2009) 3.8.4