1. Pumps

2. Goals
Describe how centrifugal and positive-displacement pumps operate and common applications.
Calculate system head requirements.
Determine head, pump efficiency, and pump. horsepower from a typical centrifugal pump curve.
Define net positive suction head (NPSH) and understand how it relates to cavitation.
Compute NPSH required by a pump.
Determine an appropriate pump (impeller diameter, efficiency, etc.) for a given required head.
Describe how to modify system to operate on the appropriate pump curve.

3. Background Fluid Moving Equipment
Fluids are moved through flow systems using pumps, fans, blowers, and compressors. Such devices increase the mechanical energy of the fluid. The additional energy can be used to increase
Velocity (flow rate)
Pressure
Elevation

4. Background
Pump, fan, blower, and compressor are terms that do not have precise meaning. Generally pumps move liquids while fans, blowers and compressors add energy to gasses.
Pumps and fans do not appreciably affect the density of the fluids that they move and thus incompressible flow theory is applicable.

5. Centrifugal Pumps
Most common type of pumping machinery. There are many types, sizes, and designs from various manufacturers who also publish operating characteristics of each pump in the form of performance (pump) curves. The device pictured on the cover page is a centrifugal pump.
Pump curves describe head delivered, pump efficiency, and net positive suction head (NPSH) for a properly operating specific model pump.
Centrifugal pumps are generally used where high flow rates and moderate head increases are required.

6. Centrifugal Pumps

7. Impeller

8. Positive Displacement Pump

9. Positive Displacement Pumps
To move fluids positive displacement pumps admit a fixed volume of liquid from the inlet into a chamber and eject it into the discharge.
Positive displacement pumps are used when higher head increases are required. Generally they do not increase velocity.

10. LVAD Application

11. Pump Head What happens if the MEB is multiplied through by g (gc/g)?
System Head
What are the units (SI)?

12. Pump Cavitation Net (above the vapor pressure) Positive Suction Head (NPSH)Pb
hfs Za Pa

13. Pump Curve Example Pump Curves (Resources Section)
What pump horsepower is required to pump 150 GPM
of water at a total head of 225 ft using a Goulds Model
3196 operating at 3540 RPM ?
What is the required NPSH ?
What is the pump efficiency ?

14. Pump Curves

15. System Response What happens when flow control valve is closed?
Tank A 2
Tank B 1 3
What happens when flow control valve is closed?
Resistance (f) increases
Flow rate decreases
Need more head to recover flow rate

16. System Response Constant Flow Response Valve Closed Valve Open
Head Response

17. 10 Minute Problem Tank B Tank A
A centrifugal pump (Goulds Model: RPM - CDS 3832) with an 11 inch impeller is used to transport water at 350 GPM through the system show below. The system head with the control valve completely open is 90 ft lbf / lbm. For the desired flow rate, it is necessary to partially close the control valve. What pressure drop across the valve is required ?
Tank B
Tank A