What are the two types of wear rings in pumps?

The correct answer identifies the two main categories of wear rings found in pumps: casing wear rings and impeller wear rings.

Casing wear rings are installed in the pump casing and serve the purpose of minimizing wear that occurs as a result of the high-velocity fluid moving through the pump. They help maintain the clearance between the casing and the impeller, which is crucial for efficient operation and longevity of the pump. Impeller wear rings, on the other hand, are found on the impeller itself and perform a similar function by preventing excessive wear that can arise from contact with the casing. Together, these wear rings help to maintain performance by reducing leakage and wear, ultimately enhancing the effectiveness and lifespan of the pump.

Other options, while they mention valid concepts related to wear or components of pumps, do not accurately describe the specific types of wear rings that are commonly recognized in pump design and application.