What plugs the space between the impeller and the casing?

• A. wear rings
• B. gaskets
• C. seals
• D. bearings

Answer: (A)

Wear rings fill the space between the impeller and the casing to control the clearance, reduce internal leakage, and preserve pump efficiency. They provide a sacrificial, replaceable surface that wears instead of the impeller or casing, keeping the annular gap tight as parts wear. Without them, fluid would slip around the impeller, lowering head and efficiency. Gaskets seal joints between stationary parts and aren’t placed between a rotating impeller and the casing. Seals prevent leakage around the shaft, not the gap between impeller and casing. Bearings support the shaft but do not fill or seal that gap.