As the pump impeller rotates, water flows into the pump through the inlet; the impeller then pressurizes the water through its rotation, causing it to flow out through the outlet. However, because a clearance exists between the impeller ring and the pump casing—and given that the water pressure within the pump chamber is higher than the pressure at the inlet—a portion of the water will flow back from the pump chamber to the inlet through this gap. This phenomenon is known as internal leakage.
After a water pump has been in operation for some time, factors such as minor friction between the impeller and the wear ring, corrosion, cavitation, and abrasive wear caused by impurities in the pumped medium can lead to an enlargement of the clearance between the impeller and the pump casing. This increased clearance exacerbates internal leakage, thereby resulting in a decline in the pump's overall efficiency.
Therefore, it is essential to perform regular maintenance on water pumps—such as adjusting concentricity and replacing components like wear rings and impellers—to ensure the pump maintains its high efficiency over time.
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