1. PUMPS AND DRIVERS
NCCER

2. 2.0.0 Pump Types
Pump – a mechanical device designed to increase the energy of a fluid so that a quantity of the fluid can be transported from one location to another.
Operate under the general principle that fluid is drawn into one end (suction) and forced out the other end (discharge) at an increased velocity.
Classified as:
Centrifugal
Positive-Displacement

3. 2.1.0 Centrifugal Pumps
Rotating impeller increases the velocity of the fluid.

4. 2.1.1 Double-Suction Centrifugal Pumps
Fluid is drawn in on both sides of the impeller.
Used to pump large volumes of fluid.

5. 2.1.2 Multi-Stage Centrifugal Pumps
Each impeller (stage) increases the velocity. Stages are stacked until the desired pressure is reached.

6. 2.1.3 Slurry Pumps
Slurry – a mixture of different fluids, with large quantities of solid particles.

7. 2.2.0 Rotary Pumps
Positive-Displacement pumps that operate by a turning motion.
Types include:
Gear
Screw
Vane
Flexible Impeller

8. 2.2.1 Gear Pumps
Fluid is drawn from the suction, around the outside of the teeth, and out the discharge.
Spur gear is the most common rotary pump.

9. 2.2.2 External Gear Pumps
Fluid is drawn from the suction, around the outside of the teeth, and out the discharge.
Can be operated in either direction.

10. 2.2.3 Internal Gear Pump Have two gears that mesh together.
Outer gear is the driving gear.

11. 2.2.4 Helical Screw Gear Pump
Pumping oil and heavy fluids.

12. 2.2.5 Vane Pumps Pumps hydraulic oil, solvents, and chemicals.
Vanes are made of soft material.

13. 2.2.6 Flexible Impeller Pumps
Rotary pumps used primarily for chemicals.

14. 2.3.0 Reciprocating Pumps
Operate by back-and-forth (or up-and-down) straight-line motion, incorporating a suction stroke and a discharge stroke.
Suction stroke:
Suction valve open; discharge valve closed.
Discharge stroke:
Suction valve closed; discharge valve open.
Delivers a pulsating flow.
To compensate for the pulsation, an air chamber is placed on the discharge line.
Three main types:
Piston
Plunger
Diaphragm

15. 2.3.1 Piston Pumps
Pumping element is a piston, which moves back and forth in the chamber.
Piston is shorter than stroke length.

16. 2.3.2 Plunger Pump Plunger moves fluid into and out of the cylinder.
Plunger length is greater than stroke length.

17. 2.3.3 Diaphragm Pumps Flexible diaphragm moves the fluid.
Ideal for caustic chemicals.
Also used for metering exact quantities.

18. 2.4.0 Metering Pumps
Due to close manufacturing tolerances, these can pump exact amounts of fluid.
Very sensitive to temperature changes and abuse.
Three types:
Plunger metering pumps
Diaphragm metering pumps
Peristaltic pumps

19. 2.4.1 Plunger Metering Pumps
The most common type used in industry today.

20. 2.4.2 Diaphragm Metering Pumps
Uses a diaphragm to move the fluid.

21. 2.4.3 Peristaltic Pumps Specialty pump for chemical applications.
Uses two shoes on a rotor to squeeze fluid along a hose.

22. 2.5.0 Vacuum Pumps
Creates a vacuum (negative pressure) instead of a positive pressure.
For double-suction vacuum pump (liquid-ring compressor):
a liquid, usually water, is used to seal the rotor and cone clearance.

23. 3.0.0 Net Positive Suction Head and Cavitation
Net Positive Suction Head (NPSH) is the amount of suction head (pressure) required to prevent vaporization of the pumped liquid.

24. 3.1.0 Cures for Cavitation
Cavitation – formation of vapor bubbles due to the NSPH available is less than the NPSH required.
At 72 F: 1 cf3 liquid water = 1,700 cf3 vapor water
Reduce cavitation by reducing vapor pressure:
Increase the static head:
Lower the pump
Raise the level in the tank
Raise the tank
Increase the pressure head:
Pressurize the tank

25. 3.2.0 Air or Vapor Blockage
Sometimes, cavitation is not caused by NPSH.
Air in system: Creates a severe lowering of NPSH and causes noise but not as destructive as cavitation.
Sources of air entering the suction:
Loose or worn packing is the most likely spot.
Leaks in valves and fittings.

26. 4.0.0 Installing Pumps
Pump installation is a performance of precision.
Suction and discharge lines must be plumb, level, and aligned.
Pump must be aligned with equipment centerline.
Drive motor must be precisely aligned with pump.

27. 4.1.0 Pre-Installation Guidelines
Baseplate:
If you get the baseplate right, the remainder of the installation will be smoother.
Aligned
Level in all directions
Correct elevation
Clean
grouted if applicable.

28. 4.2.0 Installation Guidelines
Drill/Tap holes as necessary
Set pump
Shim so that pump c-line is higher than motor
Assure pump is plumb and level
Align motor to pump
Connect suction and discharge

29. 5.0.0 Drivers Electric motors Internal combustion engines
Turbine engines (extreme high speed/volume)

30. 5.1.0 Identifying Types of Drivers
Electric motors
Constant or variable speed
Internal combustion engines
Reciprocating drivers
Turbine engines
extreme high speed

31. 5.2.0 Electric Drivers

32. 5.2.1 Variable Frequency Drivers
Speed control is adjustable so that desired flows and pressures can be achieved precisely.

33. 5.2.2 Motor Winding Field Windings:
The number of turns of wire on the stator which determines the motor strength.

34. 5.2.3 Power Optimization Electricity is expensive.
Companies are always looking for ways to reduce electrical consumption.

35. 5.3.0 Diesel Drivers Used where electricity is not available.
Used during power outages for critical pumping requirements.

36. 5.4.0 Gas Drivers
Use unleaded gasoline, liquid petroleum, or natural gas.

37. 5.5.0 Turbine Drivers Not as common as other drivers.
Most are set up to turn a driveshaft, which turns more than one pump.