Which of the following is NOT a purpose of wear rings in a pump?

Wear rings in a pump serve several critical functions. They are specifically designed to maintain hydraulic efficiency by minimizing leakage between the impeller and the pump casing, which directly contributes to the prevention of recirculation. Additionally, wear rings reduce friction in the pump by creating a controlled clearance, which helps in maintaining optimal performance and prolonging the life of the impeller and casing. They also mitigate leakage by providing a tight seal that reduces the amount of fluid that can escape from the pump casing.

However, wear rings do not play a role in supporting the shaft. The support for the shaft typically comes from other components such as bearings. These bearings are responsible for ensuring the shaft is properly aligned and can rotate freely. Therefore, saying that wear rings support the shaft is incorrect, which highlights why this answer is the right choice for the question. Understanding the specific functions of each component in a pump system is crucial for maintaining efficient operation.