What does the rotating impeller of a centrifugal pump NOT touch?

In a centrifugal pump, the rotating impeller is designed to transfer energy to the fluid and create a flow through the pump. The impeller is typically housed within the pump casing or volute, but it does not physically touch these components during operation. Instead, the impeller rotates within a close tolerance to the casing, allowing the fluid to flow around it without direct contact. This design minimizes wear and extends the lifespan of the pump components.

The other options involve components that are either part of the pump system or its supporting infrastructure. The circuit breaker is part of the electrical system that controls the pump, the suction line is where the fluid enters the pump, and the discharge port is where the fluid exits after being propelled by the impeller's action.