The document discusses centrifugal pumps, including their working mechanism, operation, advantages, and disadvantages. Centrifugal pumps use a rotating impeller to impart centrifugal force on liquid and increase pressure to pump water from a low point to a higher point. They are simple to operate but work best over a narrow range of conditions and cannot handle highly viscous liquids efficiently.

3. WHAT IS CENTRIFUGAL PUMP?
WORKING MECHANISM OF A
CENTRIFUGAL PUMP
ADVANTEGAES AND
DISADVANTAGES OF
CENTRIFUGAL PUMPS

4. Centrifugal pump works on the principle that
when a certain mass of liquid is made to rotate
along the impeller from the central axis of rotation,
it impresses a centrifugal head. It causes the water
to move radially outwards at higher velocity and
causes the water to rise to a higher level. The
motion of water is restricted by casing of pump, it
result into pressure build up. In addition , the
change in angular momentum of liquid during its
fiow reults into increase in pressure head.
The steps involved in operation of centrifugal
pump are as follows :
1.The delivery valve is closed.
2.The priming of the pump is carried out. Priming
involves the filling the liquid in suction pipe and
casing upto the level of delivery valve so that no air
pockets are left in the system.
if any air or gas pockets are left in this portion of
pump, it may result into no delivery of liquid by
the pump.

5. 3. The pump shaft and impeller is now rotated
with the help of an external source of power
like a motor or any other prime mover.
The rotation of impeller inside a casing full
of liquid produces a forced vortex which is
responsible in imparting the centrifugal head
to the liquid. It creates a vaccum at the eye of
impeller and causes liquid to rise into suction
pipe from the sump.
4. The speed of impeller should be sufficient to
produce the centrifugal head such that it can
initiate discharge from delivery pipe.
5. Now the delivery valve is opened and the
liquid is lifted and discharge through the
delivery pipe due to its high pressure.
Thus the liquid is continously sucked from
the sump to impeller eye and it is delivered
from the casing of pump through the delivery
pipe.
6. Before stopping the pump, it is necessary to
close the delivery pipe otherwise the back
flow of liquid may take place from the high
head reservoir.

6. :- The operation of filling the casing ,
impeller and suction pipe and the
portion of delivery pump upto delivery
valve is called priming.
:- In case the priming of pump is not
done and the pump is not done and the
pump is not under the operation, the water
present in the pump and suction pipe will
flow back to the sump. The space occupied
by water will be filled by air.

7. :- If the pump is now started, the air
pockets inside the impeller may give
rise to vortices and cause the
discontinuity of flow. Under these
condition, the flow of fluid does not
commence and the pump runs dry. It
causes the rubbing and seizing of the
wearing rings, increases noise level and
vibrations and finally may cause the
serious damage to pump.
:- The priming in resiprocating
pumps is not required since the
pumping is done by positively moving
the fluid out of the cylinder by the
piston. Hence, the air will be displaced
from the casing when the pump starts
and it will get a suction pressure which
will draw the fluid from the sump.

8. Priming for small pumps is done
by hand
:- A foot valve is essential at the
bottom of suction pipe
:- A funnel or priming cup is
provided to fill the water by hand.
An air vent is provided in the
casing of pump. When the water
is filled, the air escapes through
the air vent. It is closed once the
priming is completed

9.  Convert the mechanical
energy into hydraulic energy
by centrifugal force on the
liquid
 Constitute the most common
type of pumping machinery
 Used to move liquids through
a piping system
 Has two main components:
1. Stationary componets,
casing, casing cover and
bearings
2. Rotating components,
impeller and shaft
 Classified into three
categories ; Radial Flow,
Mixed Flow, Axial Flow

10. Simplest piece of
equipment in any process
plant
Energy changes occur by
virtue of impeller and
volute
Liquid is fed into the
pump at the center of a
rotating impeller and
thrown outward by
centrifugal force
The conversion of kinetic
energy into pressure
energy supplies the
pressure difference
between the suction side
and delivery side of the
pump
Liquid flow path
inside a
centrifugal pump

11. Advantages
Simple in construction and cheap
Handle liquid with large amounts of
solids
No metal to metal fits
No valves involved in pump operation
Maintenance costs are lower

12. Disadvantages
Cannot handle highly viscous fluids efficiently
Cannot be operated at high heads
Maximum efficiency holds over a narrow range
of conditions

13. •The power supplied to the pump:
Where m=mass flow rate, kg/s
DH= total discharge head,
N.m/kg
h=efficiency
…………(1)

14. •The power delivered to the fluid:
…………(2)
•From equations (1) and (2) efficiency:

15. n = n × Q
q 3 4 H
nq is the specific speed for a unit machine that
is geometric similar to a machine with the head
Hq = 1 m and flow rate Q = 1 m3/s
s q n = 51,55×n

16. Three basic
components:
Volute, casing,
body
or Diffuser
Impeller
or impellers
Driver (motor)

17. Direction of
rotation
Vanes
Centrifugal Pumps

18. Single suction impeller
Centrifugal Pumps

19. • Open
• Semi-open
• Closed
- Single suction
- Double suction
• Non-clogging
• Axial flow
• Mixed flow
Centrifugal Pumps

20. Maximum efficiency lies in the
range:
2000<NS<3000
High head, low capacity pumps:
500<NS<1000
Low head, large capacity pumps:
NS>15000

21. Rotation
Centrifugal Pumps
Vt
Impeller
Blades
V
r
V
s
Vr = Radial Velocity
Vt = Tangential Velocity
Vs = Vector Sum Velocity

22. Arrows represent the
direction of water flow Discharge
Centrifugal Pumps
Nozzle
Cutwater
Suction Eye

23. SSeerriieess 11551100
Centrifugal Pumps
• 26 sizes
– To 4400 gpm
– To 520 ft TDH
– To 150 HP To
8”x10”
– General
Purpose
Motor

24. Bell & Gossett
Series HSC
Bell & Gossett
Series HSC
Centrifugal Pumps
– 37 sizes
– To 12500 gpm
– To 840 ft TDH
– To 1000 HP
– To 14”x18”
– General
Purpose Motor

25. Typical Split Case Pump-
Section View
Centrifugal Pumps

26. Centrifugal Pumps
SSeerriieess VVSSCCSS
SSeerriieess VVSSCC
– 17 sizes
– To 8000 gpm
– To 400 ft TDH
– To 600 HP
– To 12”x14”
– General Purpose
Motor

27. Standard construction, any impeller
Mechanical seal
Internally flushed, seal
cavity
Variety of seal materials
Stuffing box construction, any impeller
External flush lines
Compression packing rings
Single flushed mechanical
seal
Centrifugal Pumps

28. Standard construction, any
impeller
Mechanical seal
Internally flushed, seal cavity
Variety of seal materials
Centrifugal Pumps

29. Temperature of the flushing
water.
225ºF to 250ºF
System pH.
7 to 9 for ceramic seals
up to 11 for tungsten carbide seals
Concentration of dissolved solids.
TDS less than 1000 ppm
Concentration of suspended
solids.
Less than 20 ppm
Silica, less than 10 ppm
Centrifugal Pumps

30. Stuffing box construction, any
impeller
External flush lines
Internal or External Fluid
Compression packing rings
Single flushed mechanical seal
Centrifugal Pumps

31. Impeller
Single suction or double
suction.
Volutes
Base mounted or in-line.
Internally flushed or stuffing
box.
Single stage or multi stage.
Packing, seal or wet rotor.
Centrifugal Pumps

32. 5 dia.
RIGHT WRONG
1. Pipe supported
2. Length of
suction piping
allows even
impeller
loading
Centrifugal Pumps
1. Pipe weight
hangs on
pump flange.
2. Short suction
pipe results in
uneven
impeller
loading.

33. Single Suction
Impeller
Centrifugal Pumps

34. The amount of fluid
The properties of the fluid
Type of power supply
Cost and mechanical efficiency of the pump