🔍 Key Concepts

• centrifugal pump construction – impeller, casing, and clearances • wear (wearing) rings on pumps vs. piston rings on engines • effects of erosion and leakage at the impeller/casing interface

💭 Think About

• Which pump parts actually touch or come very close to each other during normal operation, and what happens to those surfaces over time? • If one small, sacrificial part can be changed instead of the whole pump casing or impeller, which choice best matches that idea? • Do any of the options describe something that seems unrelated to how a centrifugal pump is built (e.g., explosions, alignment, or ‘watching it run’)?

✅ Before You Answer

• Identify where wearing rings are physically located on a centrifugal pump (impeller eye/casing interface). • Decide which option describes a part that is sacrificial and replaceable rather than a permanent structural part. • Eliminate any options that do not relate to erosion, clearance, or surface wear between rotating and stationary parts.