Which component is designed to prevent internal leakage in a pump?

• A. Impeller
• B. Casing
• C. Wearing rings
• D. Suction strainer

Answer: (C)

Wearing rings are used to minimize the internal leakage inside a pump. They sit in the pump where the impeller comes close to the casing, creating a tight clearance that reduces the flow that can squeeze past from the high-pressure side to the low-pressure side inside the pump. As wear occurs, leakage tends to increase, but these rings are replaceable, allowing you to restore the close fit and maintain efficiency and head. The impeller mainly adds energy to the fluid, the casing houses the fluid but does not actively limit the leakage path, and a suction strainer protects against debris but doesn’t control internal leakage.