When initiating operation of a centrifugal pump, how should its delivery valve be positioned___________________?
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Answer: B. Closed
Explanation
Starting a centrifugal pump with its delivery valve closed minimizes the starting torque required. This closed-valve startup prevents sudden motor overloading and reduces initial electrical current surges. Once the pump reaches full operating speed, the delivery valve can be opened gradually. Centrifugal pumps impart kinetic energy to fluids using rotating impellers driven by electric motors. Starting against a closed valve keeps flow rate at zero, minimizing power consumption for radial pumps. Opening the discharge valve too quickly upon startup can cause water hammer and motor tripping.
Water pumping stations enforce strict standard operating procedures to close discharge valves before starting. Industrial pump operators protect large electric motors from burnout by managing discharge valve positions. Irrigation systems utilize automated valves to ensure centrifugal pumps start under zero-flow conditions. Opening the delivery valve during startup causes maximum motor load and potential electrical tripping. Stating that valve position makes no difference ignores the crucial motor torque and power requirements. Fluid viscosity does not change the fundamental starting characteristic that requires closed valves.
- Subject
- Engineering
- Category
- Chemical Engineering
- Topic
- —
- Difficulty
- medium
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