🔍 Key Concepts

• Centrifugal pump characteristics when suction is restricted • How cavitation develops at the eye of the impeller • Relationship between capacity (flow), efficiency, and NPSH when throttling on the suction vs. discharge side

💭 Think About

• Think about what happens to the pressure at the pump inlet when you close down (throttle) the suction valve—does it go up or down, and how does that affect the liquid? • Compare the usual, recommended way to control flow on a centrifugal pump (suction side or discharge side?) and recall why one method is avoided. • Consider which of the listed outcomes is gradual and related to performance, and which are extreme failures that would more likely require severe misoperation or long abuse.

✅ Before You Answer

• Verify what low NPSH (Net Positive Suction Head) does to liquid at the pump inlet and how that relates to bubble formation and noise/vibration. • Check which option mentions both reduced efficiency and a phenomenon specifically associated with low inlet pressure. • Eliminate choices that describe immediate catastrophic damage (like instant seizure or irreparable shaft damage), and favor the one that describes a realistic operational consequence of throttling the suction.