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Performance Curves

Performance Curves. Dr. C. L. Jones Biosystems and Ag. Engineering . Performance Curves. System curve. Dr. C. L. Jones Biosystems and Ag. Engineering . Review: Centrifugal Pump Affinity Laws. Dr. C. L. Jones Biosystems and Ag. Engineering . Centrifugal Pump Affinity Laws.

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Performance Curves

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  1. Performance Curves Dr. C. L. Jones Biosystems and Ag. Engineering

  2. Performance Curves System curve Dr. C. L. Jones Biosystems and Ag. Engineering

  3. Review: Centrifugal Pump Affinity Laws Dr. C. L. Jones Biosystems and Ag. Engineering

  4. Centrifugal Pump Affinity Laws Dr. C. L. Jones Biosystems and Ag. Engineering

  5. Centrifugal Pump Fundamentals • Static head: the height of a column of liquid • Units: feet or meters • Pump imparts velocity to liquid…velocity energy becomes pressure energy leaving the pump. Head developed = vel. energy at the impeller tips. • Why do we use “feet” or “head” instead of “psi” or “pressure”? • Pump with impeller D will raise a liquid to a certain height regardless of weight of liquid Dr. C. L. Jones Biosystems and Ag. Engineering

  6. Converting pressure, psi, to head in feet Dr. C. L. Jones Biosystems and Ag. Engineering

  7. Suction Lift Dr. C. L. Jones Biosystems and Ag. Engineering

  8. Suction Head Dr. C. L. Jones Biosystems and Ag. Engineering

  9. Static Discharge Head • Static Discharge Head = vertical distance from pump centerline to the point of free discharge or the surface of the liquid in the discharge tank. Dr. C. L. Jones Biosystems and Ag. Engineering

  10. Total Static Head • Vertical distance between the free level of the source of supply and the point of free discharge or the free surface of the discharge liquid. Dr. C. L. Jones Biosystems and Ag. Engineering

  11. Total Dynamic Suction Lift or Head • (fluid below suction) Static suction lift - velocity head at suction + total friction head in suction line • (fluid above suction) Static suction head + velocity head at pump suction flange – total friction head in suction line • Velocity head = energy of liquid due to motion, Usually insignificant Dr. C. L. Jones Biosystems and Ag. Engineering

  12. Total Dynamic Discharge Head • Static discharge head + velocity head at pump discharge flange plus discharge line friction Total Dynamic Discharge Head (TH or TDH) (this is what we design for!!!) • Total dynamic discharge head – total dynamic suction head (tank above suction)…. Or…. • Total dynamic discharge head + total dynamic suction lift (tank below suction) Dr. C. L. Jones Biosystems and Ag. Engineering

  13. Total Dynamic Discharge Head (TH or TDH) (this is what we design for!!!) TDH includes friction losses due to piping and velocity Dr. C. L. Jones Biosystems and Ag. Engineering

  14. One last item to consider…NPSH (net positive suction head) Dr. C. L. Jones Biosystems and Ag. Engineering

  15. NPSHR Dr. C. L. Jones Biosystems and Ag. Engineering

  16. NPSHA Dr. C. L. Jones Biosystems and Ag. Engineering

  17. NPSHA Dr. C. L. Jones Biosystems and Ag. Engineering

  18. Capacity, Power, Efficiency • Capacity Q, gpm = 449 x A, ft2 x V, ft/sec Where A = cross-sectional area of the pipe in ft2 V = velocity of flow in feet per second • Bhp = actual power delivered to pump shaft by driver • Whp = pump output or hydraulic horsepower Dr. C. L. Jones Biosystems and Ag. Engineering

  19. Pump Efficiency Ratio of whp to bhp: Dr. C. L. Jones Biosystems and Ag. Engineering

  20. System Example: 80 ft of 4” ID galv. iron pipe with 3 elbows, 75’ lift, pumps from an open tank, discharges through a pipe to a tank at atm. Pressure (find rate, imp. dia., eff., motor size, rpm) Ratio of whp to bhp: Dr. C. L. Jones Biosystems and Ag. Engineering

  21. Questions??? Dr. C. L. Jones Biosystems and Ag. Engineering

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