🔍 Key Concepts

• Centrifugal pump characteristic curve (how pressure and flow change as discharge valve closes) • Difference between positive displacement pumps and centrifugal pumps when a discharge valve is shut • What happens to discharge pressure and relief valves when flow is restricted

💭 Think About

• As you slowly close the discharge valve on a centrifugal fire pump, what should normally happen to discharge pressure and flow? • In a healthy centrifugal pump, what effect does fully closing the discharge valve have compared to partially closing it? • Which answer choice best matches the behavior of a centrifugal pump that is actually not pumping the way it should?

✅ Before You Answer

• Confirm how discharge pressure typically reacts on a centrifugal pump as the discharge valve goes from fully open toward closed • Recall whether centrifugal pumps must have a relief valve lift when the discharge is restricted, or if something else would be seen first • Check which option describes a condition where changing valve position does not change the pump’s discharge pressure, indicating a possible loss of pumping action