The purpose of wear rings in a centrifugal pump is to:

• A. Prevent Wearing of the Pump Housing and Impeller
• B. Increase Net Positive Suction Head
• C. Reduce Vibrations
• D. Improve Sealing

Answer: (A)

Wear rings are sacrificial, replaceable surfaces placed between the impeller and the pump housing to take the wear that occurs during operation. By providing a tight, controlled clearance, they protect the more expensive impeller and casing from wear while keeping internal leakage to a minimum. When the rings wear, the gap would widen and efficiency and head would drop, so the rings are designed to be replaced to restore proper clearance and performance. This protective, serviceable role is why their main purpose is to prevent wearing of the pump housing and impeller.

The other options don’t fit as the primary purpose: net positive suction head is determined by suction conditions and pump design rather than wear rings; vibrations are not the primary function of wear rings, although improper clearance can influence vibration; and sealing is handled by seals, not the wear rings.