This presentation consists general aspects of water pump. Further basic knowledge regarding priming, cavitation and maintenance of water pump can be obtained by referring this presentation . In addition formulas to find out total head, friction head, specific speed, economic diameter, Water Horse Power, Brake Horse Power and efficiency of motor, pump and pumping plant also have been included in this presentation. .

1. Water pump
Vijitha Vikneshwaran
Lecturer (Temporary)
Faculty of Technology
University of Jaffna

2. Introduction
• Water is important to sustain the plant growth.
• It can be pumped from various sources like,
• Canals
• Wells
• Ponds
• For lifting the water the following basic factors
should be taken into account.
• Source of water
• Device used for lifting
• Power source for operating such device
• Connecting arrangements
2

3. Introduction,cont….
• Pumps used for irrigation are available in a wide variety of
pressure and discharge configurations.
• Pressure and discharge are inversely related in pump design.
• The pumps which produce high pressure have relatively small
discharge and vice versa.
• Most of local famers use 4SPE driven centrifugal pumps.
3

4. Different types of water lifting
Figure 01: Manual lifting Figure 02: Rope pump
4

5. Differenttypesofwaterlifting,cont……
Figure 03: Treadle pump Figure 04: Lifting by suction
5

6. Mechanised Pumping
Power source Principle
Grid Centralized power plant produces and distributes electricity
via power grid. Electricity drives a pump
Solar Solar panels produce electricity which drives the pump
Diesel generator Fuel driven engine produces rotation which is then
transformed to electricity and drives the pump
Fuel engine Fuel driven engine produces rotation which drives the pump
directly
Wind power Wind mill produces rotation which drives the pump directly
Animal driven Animals produce rotation which drives the pump directly
Hydro power Hydraulic ram
6

7. • Capacity of pump
• Importance of water supply
• Initial cost of pump
• Maintenance cost
• Space requirements
• Number of units required
• Total lift of water required
• Quantity of water to be produced
Criteria for pump selection
7

8. 8
Components of centrifugal pump
Figure 05: Components of centrifugal pump

9. Casing
• It contains the liquid and acts as a pressure containment
vessel that directs the flow of liquid in and out of the
centrifugal pump.
• Impellers are fitted inside casings.
• Convert kinematic energy into pressure energy.
• Reducing speed while increasing pressure.
• Seal it to prevent leakage and sometimes retain pressure.
• Support some of the key parts such as shafts, bearings, etc.
Componentsofwaterpump,cont….
Figure 06: Casing
9

10. Impellers
1. Open impeller
• It has the vanes free on both sides
• Open impellers are structurally weak
• Use in small-diameter, inexpensive pumps and in pumps
handling suspended solids
Componentsofwaterpump,cont….
Figure 07: Open impeller
10

11. 2. Closed impeller
• The vanes are located between the two discs, all in a
single casting.
• Use in large pumps with high efficiencies and low
required Net Positive Suction Head
• The centrifugal pumps with closed impeller are the most
widely used pumps handling clear liquids.
11
Componentsofwaterpump,cont….
Figure 08: Closed impeller

12. 3. Semi open impeller
• The vanes are free on one side and enclosed on the other side.
• The shroud adds mechanical strength
• Higher efficiency compare to open impellers
12
Componentsofwaterpump,cont….
Figure 09:Semi open impeller

13. Coupling
• Join two pieces of rotating equipment while permitting
end movement
• Connect the pump shaft and the driver shaft
• Transmit the input power from the driver into the pump
Componentsofwaterpump,cont….
Figure 10: Coupling
13

14. Coupling sleeve
• Elastomeric material such as EPDM rubber and neoprene
• It is a mechanical connection
• Used to make the system air tight and control the water
leakage
Componentsofwaterpump,cont….
Figure 11 : Coupling sleeve
14

15. Componentsofwaterpump,cont…
Flywheel
• A rotating mechanical device that is used to store
rotational energy.
• It acts like a reservoir and store the energy in the
mechanical form.
• Supply energy to the centrifugal pump
• Drive the pump impeller running and pumping the liquid
to protect the machine
Figure 12: Flywheel
15

16. Water seal
• The mechanical seal acts as a check valve and a slider
bearing.
• Check valve to prevent liquid under pressure from leaking
out of the pump, or from drawing air into the pump when
under vacuum conditions.
Componentsofwaterpump,cont….
Figure 13: Water seal
16

17. Foot valve
• Made of PVC plastics or stainless steel.
• It is a one direction and valve provided at the foot of the
suction pipe.
• It permits flow only in one direction.
• Foot valve facilitates to hold the primed water in the
suction pipe before starting the pump.
Componentsofwaterpump,cont…
Figure 14: Foot valve
17

18. Shaft
• Impeller is mounted on a shaft.
• Shaft is a mechanical component for transmitting
torque from the motor to the impeller.
Ball bearing
• Uses balls to support the movement of the parts.
• It supports the shaft to rotate smoothly.
• They are simple in design and are suitable for high
speeds and easy to maintain.
• Ball bearings are good for radial load and axial load.
Componentsofwaterpump,cont…
18

19. Counter weight
• Eliminate or reduce water hammer and prevent working
medium from reversal flow.
• Closing time and speed can be regulated.
• Counter weight fails, as it usually sticks in the open
condition.
• This results in the load slowly drifting downward
Componentsofwaterpump,cont…
Figure 15: Counter weight
19

20. Strainer
• It is a screen provided at the foot of the suction pipe.
• It would not allow entrance of the solid matters into the suction
pipe.
• Prevent the damage of the pump
• Strainer is clogged in the suction pipework or discharge pipe,
this will have the effect of increasing pressure loss thereby
decreasing flow.
Componentsofwaterpump,cont…
Figure 16: Strainer
20

21. How a centrifugal pump works
21
Figure 17: Working principle of centrifugal pump

22. • The pump is filled with water and the impeller is rotated.
• The blades cause the liquid to rotate with the impeller and
in turn impart a high velocity to the water.
• Centrifugal force causes it to be thrown outward from the
impeller into casing.
• The outward flow through the impeller reduces pressure at
the inlet, allowing more water to be drawn in through the
suction pipe by atmospheric pressure or external pressure.
• The liquid passes in to the casing where the high velocity is
reduced and converted into pressure.
• And then water is pumped out through the discharge pipe.
22
Howacentrifugalpumpworks,cont….

23. • Priming is the process of,
filling of water in centrifugal pump from foot valve
to delivery valve including casing before starting the pump.
• It maintains the hydraulic pressure to keep the water flow
in accordance with the given setting.
• Priming is required above the water level however not
needed below the water level.
Priming
23

24. Priming,cont…
Figure 18: Priming of centrifugal pump
24
• When there is no gravity flow to the pump, three other
methods are commonly used:
• From an outside source with a funnel
• Via a return line with check valve from the delivery system
• With a vacuum pump
• In self-priming pumps generally only the pump has to be filled
with water.

25. Self priming
• Pump has the ability to use liquid stored in its housing to
generate a vacuum on the suction line.
• Counter balance keep in pump case
• Even a ‘self-priming’ centrifugal pump will not operate
when dry.
• Self-priming centrifugal pump has two phases of
operation:
• Priming mode
• Pumping mode
25

26. Cavitation
• The cavitation is,
• the formation of vapor bubbles of flowing liquid in a
region where the pressure of the liquid falls below its
vapor pressure
and
• the sudden collapsing of this vapor bubbles in a region
of higher pressure.
26

27. • The formation and the collapse of a great number of bubbles
on the surface produce intense local stresses.
• It damages the surface by fatigue.
• It may occur at the entry to pumps or at the exit from
hydraulic turbines in the vicinity of the moving blades.
27
Cavitation,cont……
Figure 19:Cavitation phenomena

28. Cavitationcont.…
The cavitation can cause:
• Failure of pump housing
• Destruction of impeller
• Excessive vibration - leading to premature seal and bearing
failure
• Higher than necessary power consumption
• Decreased flow and/or pressure
28
Figure 20:Destruction of impeller due to cavitation

29. Cavitation,cont….
Prevention of cavitation
• Check filters and strainers - Clogs on the suction or
discharge side can cause an imbalance of pressure inside
the pump.
• Reference the pump's curve - Use a pressure gauge and/or
a flowmeter to understand where your pump is operating
on the curve.
• Re-evaluate pipe design - Ensure the path the liquid takes
to get to and from your pump is ideal for the pump's
operating conditions. 29

30. Pumping station
• Factors should be considered while selecting a pumping
station.
• Away from contamination
• Above the highest hood level
• Future expansion
• Hazard possibility
• During pump setting, it can be placed below the level of
water in the sump well or above it.
30

31. Piping and valves of pumping station
• Can’t use iron pipes using flanged joints.
• Average flow velocity 0.6 to 1.2 m/s.
• Sluice or gate valve- one on station side and other on delivery side.
• A check valve on delivery side in between pump and gate valve.
• A pressure relief valve on delivery side.
31

32. Pump, hose and foot valve connection
Suction piping
• It is used to supply an evenly distributed flow of water
to the pump suction, with sufficient pressure to the
pump.
• Suction piping should be adequately sized and properly
designed to avoid cavitation.
• Excessive turbulence in the pump impeller should be
avoided.
• Pump suction problems
• Poor pump performance
• Poor bearing life
• Poor mechanical seal performance
32

33. Pump,hoseandfootvalveconnectioncont..
Delivery piping
• It is the lower end to the out let of the pump.
• It delivers the liquid to the required height.
• Near the outlet of the pump on the delivery pipe, a
valve is provided which controls the flow from
the pump into delivery pipe.
33

34. Possible problems & their causes in pump
1. No or low flow
• Pump is not primed
• Valves are closed or there is an obstruction in the
suction
• The end of the suction pipe is not submerged
• A strainer or filter is clogged
• Air leak in the suction pipe
• No power to the pump
• Pump speed too low

35. Possibleproblemsandcausesinpump,cont…
2. No or low pressure
• Valves are closed or there is an obstruction in the suction or
discharge pipework
• A strainer or filter is clogged on the inlet
• The motor is turning pump in the wrong direction
• Insufficient Net Positive Suction Head available (NPSHa)
• Pump speed too low
3. Excessive power consumption
• Flow is higher than calculated with low outlet pressure
• Viscosity too high
• Mechanical contact in the pump head

36. Possibleproblemsandcausesinpumpcont.…
4. Excessive noise or vibration
• Pipework is not properly supported
• Cavitation
• Impeller contact with casing
• Loss of shaft support (bearing failure in motor)
• Pumped media contains unexpected abrasive particles
5. Seal leakage
• Pumped media contains unexpected solids
• Chemical corrosion / attack
• Pump is cavitating
• Too high discharge pressure and temperature
• Pump / shaft vibration
• Incorrect selection of seal materials
• Insufficient or no auxiliary flushing services

37. Maintenance
• Performance of the pump should be observed daily
• The alignment of the pump unit should checked
occasionally
• Bearings should be lubricated regularly
• Avoid the contact with sunlight , rain water
• Good ventilation should be provided

38. • Power supply should be provide with standard
accessories.
• Check oil drain plug
• Inspect suction and discharge flanges for any leak.
• Inspect pump casing for any unusual damage signs.
• Inspect the seal.
• Don’t operate during rainy & lower supply period 38
Maintenance,cont….

39. Head, power & efficiency of pumps
39
Total head (H) consists of,
• Suction head (Hs)
• Delivery head (Hd)
• Friction head (HL)
H= Hs +Hd + HL
Where,
HL=
𝒇𝟏
𝑳𝒗𝟐
𝟐𝒈𝒅
=
𝒇𝟏
𝑳𝑸𝟐
𝟐𝒈
𝝅
𝟒
𝟐
𝒅𝟓

40. Headpower&efficiencyofpumpscont.……
40
• The work done by the pump in lifting Q (m3/s) of water by a
head H (m) can be calculated as;
Work done = 𝐰𝑸𝑯 kgm/s
w- Unit weight of water in kg/m3
Q- Discharge to be pump in m3/s
H- Total head in m
• Water horse power of pump is given by:
WHP =
𝐰𝐐𝐇
𝟕𝟓
• If ᶯ is the efficiency of the pump, the break horse power
(BHP) is given by
BHP =
𝑾𝑯𝑷
ᶯ
=
𝒘𝑸𝑯
𝟕𝟓∗ᶯ

41. Ep = WHP / BHP
Em = BHP/ input
EPP = WHP/ input
= Ep . Em
Where,
Em = Efficiency of motor
Ep = Efficiency of pump
EPP = Efficiency of pumping plant
41
Headpower&efficiencyofpumpscont.……

42. • It is a speed at which pumps will discharge a unit flow at
maximum efficiency.
Ns = 51.66[N
𝑸
𝟏
𝟐
𝑯
𝟑
𝟒
]
Where;
• H- Head (m)
• Q- Discharge (m3/s)
• N- Speed (rpm)
• Ns- Specific speed (rpm)
Specific speed
42

43. Economical diameter of pumping mains
• The diameter which provides optimum conduits is known
as economical diameter.
• diameter < economical diameter– low cost / high loss
diameter > economical diameter– high cost
Lea’s formula for economical diameter is
D = 0.97 to 1.22 𝑄
Where,
Q- Discharge to be pumped in m3/s

44. Annual
cost
Economical diameter
Lowest cost
Size of pipe
Economicaldiameterofpumpingmains,cont…
Figure 26 : Curve for Economic diameter

45. Shutoff
head
Rated
capacity
Rated
hp
Pump Performance and Efficiency Curves
Figure 27 : Characteristic curve
45

46. THANK YOU
46