Throttling the discharge of a centrifugal pump causes its suction lift to_______________________?
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Answer: A. Increases
Explanation
Throttling the discharge valve of a centrifugal pump reduces the overall volumetric flow rate. Lower flow rates significantly decrease friction head losses within the suction piping. Reduced suction line friction raises the effective pressure at the pump inlet, increasing suction lift. Centrifugal pump performance curves show that flow rate decreases as discharge head increases. Suction lift represents the height to which a pump can lift liquid from a lower source. Friction losses in pipes are proportional to the square of the fluid velocity inside them.
Operators throttle discharge valves during startup to minimize starting torque and motor load. Understanding suction lift behavior prevents cavitation issues when handling high suction lifts. This operational characteristic helps troubleshoot pumping problems in industrial process plants. Decreasing suction lift is incorrect because lower flow rates reduce suction line pressure drops. Stating suction lift remains unchanged ignores the direct fluid friction dependency on flow velocity. Sufficient data is definitely available through standard centrifugal pump performance principles.
- Subject
- Engineering
- Category
- Chemical Engineering
- Topic
- —
- Difficulty
- medium
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