1. Review from Lecture 1: Pumps
Difference between pumps, fans, and compressors
Mechanical Efficiency
Power Output (English units, HP, psi, gpm)
Dr. C. L. Jones
Biosystems and Ag. Engineering

2. Review from Lecture 1: Pumps
Two types
Flow rates
Pressure
Flow characteristics
Displacement
- plunger
- piston
- rotary
Low
High
Pulsating
Dynamic
- centrifugal
- jet
- airlift
Steady Flow
Dr. C. L. Jones
Biosystems and Ag. Engineering

3. Review: Dynamic Pumps Centrifugal Relative simplicity
Can handle fluids containing suspended solids
Ease of maintenance…good for food products
2 parts: impeller and casing
Radial, mixed, axial flow
Dr. C. L. Jones
Biosystems and Ag. Engineering

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

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

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

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

8. 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

9. Converting pressure, psi, to head in feet for water (Psurface-Pvapor) = 1
Dr. C. L. Jones
Biosystems and Ag. Engineering

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

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

12. 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

13. 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

14. 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

15. 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

16. TDH includes friction losses due to piping and velocity
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

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

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

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

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

21. Capacity, Power, Efficiency
Capacity Q, gpm = 449 x A, ft2 x V, ft/sec
Where A = cross-sectional area of the pipe in ft 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

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

23. System Example: 80 ft of 4” ID galv
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

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