Wearing rings are installed in a pump to prevent ____

• A. External leakage
• B. Overheating
• C. Internal leakage
• D. Cavitation

Answer: (C)

Wearing rings limit the internal leakage inside a pump by sealing the clearance between the impeller and the casing. This slip flow from the high-pressure discharge back toward the suction reduces the pump’s head and efficiency. Replacing or restoring worn wear rings restores the proper small clearance, lowering internal leakage and bringing performance back toward the design point. They aren’t meant to stop external leaks, overheating, or cavitation, which have different causes such as seal integrity, thermal issues, or vapor pocket formation.