1. Lecture 4
Fluid Mechanics II
Muhammad Usman

2. Pumps Classifications
Pumps
Positive Displacment
Dynamic Pumps
Pumps
Reciprocating Rotary Pumps Diapharm Pumps Centrifugal Pumps
Single Acting Gear Pump Axial Flow
Doubel Acting Lobe Pump Radia Flow
Screw Type Mixed Flow
Vane Type Pump

3. Centrifugal Pumps

4. Parts of the centrifugal Pump
• Pump casing (Vent to remove gases)
• Pump shaft
• Volute
• Diffuser
• Impeller
• Stuffing box
• Lantern Ring
• Impeller wearing ring
• Pump casing wearing ring

5. Two Types of Volute casings

6. Diffusers

7. Types Of impellers
Open, Semi open and closed.

8. Radial Flow Centrifugal Pumps

9. Axial Flow Centrifugal Pumps

10. Mixed Flow Centrifugal Pumps

11. Multi-Stage Centrifugal Pump

12. Wearing Rings
• Wearing rings are replaceable rings that
are attached to the impeller and/or the
pump casing to allow a small running
clearance between the impeller and the
pump casing without causing wear of the
actual impeller or pump casing material.

13. Parts of Centrifugal Pump

14. Stuffing Box
• The stuffing box is a cylindrical space in
the pump casing surrounding the shaft.
Rings of packing material are placed in
this space. Packing is material in the form
of rings or strands that is placed in the
stuffing box to form a seal to control the
rate of leakage along the shaft.

15. Lantern Ring
• A lantern ring is a perforated hollow ring
located near the center of the packing box
that receives relatively cool, clean liquid
from either the discharge of the pump or
from an external source and distributes
the liquied uniformly aroung the shaft to
provide lubrication and cooling.

16. Mechanical Seals
• These have two basic parts, a rotating
element attached to pump shaft and
stationery element attached pump casing.

17. Cavitation
• The process of formation and subsequent
collapse of vapor bubbles in a pump is
called cavitation.
• It degrades the performance of the pump
and it can also cause extensive vibration
which could damage the pump bearing,
wearing rings and seals.

18. Net Positive Suction Head
• The net positive suction head available
(NPSHA) is the difference between the
pressure at the suction of the pump and
the saturation pressure for the liquid being
pumped.

19. Preventing Cavitation
• Increasing the suction pressure by
increasing the level of liquid in the tank.
• By decreasing the temperature of the
liquid.
• By decreasing the head losses increasing
the pipe diameter, reducing number of
elbows, valves and decreasing the length
of the pipe.
• By using additional prallel pumps.

20. Centrifugal Pump Characteristic
Curve

21. Priming of the Centrifugal Pump
• The filling of pump casing before the start
up is called priming of the pump.

22. Reciprocating Pumps
• Suitable for less discharge and higher
heads.
• A positive displacement pump is one in
which a definite volume of liquid is
delivered for each cycle of pump
operation.

23. Air Vessels
• An air vessel is a cast iron closed
chamber having an opening at its base
through which the water flows into the
vessel or from the vessel.
• The purpose of using the air vessel to
obtain unifrom discharge from the
reciprocating pump.

24. Rotary Pumps
• Self primed due to their capacity to
remove air from the suciton line.
• These pumps are used for systems
require high suction lift.
• These are positive displacement and have
constant discharge.

25. Gear Pump

26. Lobe Pump

27. Screw Pump

28. Vane Type Pump

29. Diaphragm Pump