How Wear of a Centrifugal Pump Wear Ring Affects Leakage, Head, and Efficiency
A worn wear ring can reduce a centrifugal pump’s useful output without producing an external leak. The change takes place inside the pump: an enlarged running clearance may allow more liquid to return from a higher-pressure region to a lower-pressure region. This discussion applies to pumps fitted with the relevant wear-ring arrangement. Ring locations and replaceable components differ between designs. Do not assume every centrifugal pump has the same suction-eye arrangement or replacement limits. Where the loss occurs At a typical impeller-eye wear-ring interface, the running clearance limits internal leakage while allowing the rotating and stationary parts to operate without contact. Under otherwise comparable conditions, an enlarged clearance generally increases leakage. Some liquid that has already received energy passes back through the gap and must be handled again instead of becoming useful discharge flow. Volumetric losses therefore increase. The accompanying photograph sho...
