pumps for water supply and wastewater

1. CONVEYANCE OF WATER
PUMPS AND PUMPING STATIONS
Thejus Engineering College

2. PUMP
 A pump is a device which converts
mechanical energy into hydraulic energy.
 It lifts water from a lower to a higher level
and delivers it at high pressure

3. PURPOSE OF PUMPING
 To lift raw water from wells.
 To deliver treated water to the consumer at
desired pressure.
 To supply pressured water for fire hydrants.
 To boost up pressure in water mains.
 To fill elevated overhead water tanks.
 To back-wash filters.
 To pump chemical solutions, needed for water
treatment.

4. CLASSIFICATION OF PUMPS
Displacement pumps
Reciprocating pumps
Rotary pumps
Rotodynamic pumps
Centrifugal pumps
 Axial flow pumps
Miscellaneous pumps
air lift pumps
hydraulic rams

5. DISPLACEMENT PUMPS
 A pump in which liquid is moved out of the pump
chamber by a moving surface or by the
introduction of vacuum in a chamber.
Reciprocating pumps
Rotary pumps

6. RECIPROCATING PUMP
Displacement pumps

7. COMPONENTS-RECIPROCATING PUMP
 Cylinder - it is made of cast iron or steel alloy.
 Piston - the piston reciprocates inside the cylinder.
 Connecting rod - it connects piston and rotating crank.
 Suction pipe- it connects the source of water and
cylinder.
 Delivery pipe - water sucked by pump is discharged
through the delivery pipe.
 Suction valve - it adjusts the flow from the suction pipe
into delivery pipe.
 Delivery valve - it admits the flow from the cylinder into
the delivery pipe.
Displacement pumps

8. Displacement pumps

9. RECIPROCATING PUMP
Advantages
 High efficiency
 No priming needed
 Can deliver water at high
pressure
 Can work in wide pressure
range
 Constant rate of discharge
at variable heads
 Durable and flexible
Disadvantages
 More parts mean high
initial cost (4 times than
centrifugal pumps)
 High maintenance cost
 No uniform torque
 Low discharging capacity
 Pulsating flow
 Difficult to pump viscous
fluid and fluid with
sediments
 High wear in parts
 Large space requirements
Displacement pumps

10. ROTARY PUMPS
 The rotary motions if obtained using cames or
gears
with cames with gears
Displacement pumps

11. COMPONENTS
 The pumping system consists of a housing
 an eccentrically installed rotor
 vanes /cames that move radically under spring
force
 inlet valve is designed as a vacuum safety valve
that is always open during operation
 outlet valve is oil-sealed
 working chamber is located inside the housing
Displacement pumps

12. WORKING OF ROTARY VANE PUMP
 Rotor and vanes divide the working chamber into
two separate spaces having variable volumes.
 As the rotor turns, gas flows into the enlarging
suction chamber until it is sealed off by the second
vane.
 The enclosed gas is compressed until the outlet
valve opens against atmospheric pressure.
 The Rotor moves with the help of a motor attached
to it.
Displacement pumps

13. Displacement pumps

14. Displacement pumps

15. ROTARY PUMPS
 No priming required
 Flow is free from
pulsations
 Simple to construct
 Efficiency high for
moderate heads and
smaller discharges
 High initial cost
 Not durable-frequent
replacement of cames
and gears
 Water with sediments
destroy pumps
Advantages Disadvantages
Displacement pumps

16. ROTODYNAMIC PUMPS
 A rotodynamic pump is a pump that uses the
rotation of an impeller or propeller to impart
velocity to a liquid.
Centrifugal pumps
Axial flow pumps

17. CENTRIFUGAL PUMPS
 Radial flow and mixed flow machines are called
centrifugal pumps
 Open – hub to which vanes are attached
 Closed – plates on both sides of vane
 Casing of radial flow type centrifugal pump may be
of
 Volute type
 Turbine type
Rotodynamic pumps

18. VOLUTE TYPE CENTRIFUGAL PUMP
 Impeller discharges into a
gradually expanding spiral
casing.
 It produces an equal velocity
around the circumference and
to reduce the velocity of water
as it enters discharge pipe.
Thus creating required
pressure head.
Rotodynamic pumps

19. TURBINE TYPE OR DIFFUSER TYPE
CENTRIFUGAL PUMP
 Impeller is surrounded by
stationary guide vanes
which reduces the
velocity of water before
water enters the casing.
 The casing is generally
circular and concentric
with impeller.
 Velocity of water is more
completely converted into
pressure head
 High efficiency
Rotodynamic pumps

20. COMPONENTS
CENTRIFUGAL PUMP
 An impeller – increase pressure of liquid
 Casing – acts as pressure containment vessel,
helps in flowing water out of pump
 Shaft – transmit input power from driver to the
impeller
 Seal – prevent leakage of pumped liquid to
atmosphere
 Bearings – support weight of shaft assembly, carry
hydraulic load, keep pump shaft aligned to shaft of
the driver
 Coupling – connect pump shaft and driver shaft,
transmit the input power from driver into pump
Rotodynamic pumps

21. Rotodynamic pumps

22. Rotodynamic pumps

23. CENTRIFUGAL PUMP
 As there is no drive seal so
there is no leakage in pump
 It can pump hazardous
liquids, silts also
 There are very less frictional
losses, high efficiency
 There in almost no noise
 Centrifugal pump have
minimum wear with respect
to others
 Compact size and small
space requirements
 Discharge obtained is steady
and non pulsating
 Priming is required
 High pressure should be
avoided.
 Because of the magnetic
resistance there is some
energy losses
 Unexpected heavy load
may cause the coupling
to slip
 High head efficiency is
low (50-80 %)
 Discharge varies with
head of water
Advantages Disadvantages
Rotodynamic pumps

24. AXIAL FLOW PUMPS
 Axial flow machines are called axial flow pumps
 An axial flow pump has a propeller-type of impeller
running in a casing.
 The pressure in an axial flow pump is developed by
the flow of liquid over the blades of impeller.
 The fluid is pushed in a direction parallel to the
shaft of the impeller
Rotodynamic pumps

25. AXIAL FLOW PUMP
 Can be adjusted for
best efficiency at
varying conditions
 Wide range of pressure,
flow & capacities
 Highest flow rates
 No excess pressure
build up
 High cost
 Relatively high weight
 High power
requirements
 Not suitable for suction
lift
 Cannot handle high
viscous fluids
Advantages Disadvantages
Rotodynamic pumps

26. APPLICATIONS
 Positive Displacement Pumps
 Rotary
 Metering
 Pulsed Delivery i.e. fuel injection for engines
 Reciprocating
 Suction Lift
 Axial Pumps
 Sewage handling—Domestic, Industrial, Commercial
 Agriculture—Lift water for irrigation
 Wastewater treatment plants

27. AIR LIFT PUMPS
 Used for pumping water from deep wells for lift of
about 60 – 80m.
 Can be used for high lifts about 150 metres but
their efficiency is generally low (25-50%)
 Compressed air is forced into the well through a
small pipe
 Released through a diffuser into the eduction pipe
 Air water mixture in the eduction pipe is lighter and
the forced upward by hydrostatic pressure

29. AIR LIFT PUMP
 Inspite of low efficiency, an
air lift pump can deliver large
amounts of water from small
dia wells.
 Not harmed by sedimented
water.
 Cheaper, reliable and simple
in operation
 No moving parts which may
be in contact with water–
used for highly acidic or
alkaline water.
 Yield of a well, using such
pump, can be increased by
using more amount of
compressed air.
 Not adopted for raising water
much above the ground level,
and if this is necessary, a
second pump has to be
installed.
 Efficiency is low
 Flow obtained is not
continuous but is intermittent.
 Less flexible in fulfilling variable
demands.
 In order to obtain sufficient
value of submergence, the
depth of submergence has to
be increased and thus the well
has to be made deeper than
required. This increases the
cost.
Advantages Disadvantages

30. HYDRAULIC RAM
 A kind of pumping arrangement which does not
utilise any outside power and uses the principle of
water hammer pressures developed when a
moving mass of water is suddenly stopped.
 A large amount of water must be available at
moderate head, so as to lift small amount of water
to higher head.
 Can be used for lifts of order of 30m or so.

31. Hydraulic Ram

32. HYDRAULIC RAM
 Its working is simple
and when once it starts
functioning, practically
no attention is required.
 The Ram is durable.
 It is cheap as it does
not require any fuel.
 Considerable amount
of water is wasted
through a waste valve,
and cannot be used at
places where water is
scarce.
 It produces
considerable noise
while working.
ADVANTAGES DISADVANTAGES

33. JET PUMPS
 Used for pumping water from small wells.
 Used for constructional works for dewatering
trenches.
 Efficiency is low (25%)
 Compact and light in weight
 Can also handle waters containing sediments
without much trouble.

34. JET PUMPS

35. SELECTION OF PUMP
 Capacity of pump
 Importance of water supply scheme
 Initial cost
 Maintenance cost
 Space requirements for location of pumps
 Number of units required
 Total lift of water required
 Quantity of water to be pumped

36. PUMPING STATION

37. PUMPING STATION - LOCATION
 The site should be away from all sources of
contamination
 Site should be above highest flood level
 It should be such that the future expansion is easily
possible
 Possibilities of fire hazards also be considered
 Proximity of site to railways/ roads should be
considered (availability of fuels)

38. PUMPING STATION
 Pumps can be placed above or below the sump water
level
 Cast iron pipes using flanged joints are provided
 Velocity varies between 0.6-1.2 m/s at average flows
 Various valves are provided
 Gate valve
 Check valve
 Air valve
 Pumps of variable capacities are used so as to take
care of the demand variation (peak, average)
 Stanby pumps are provided (in case of brake down)

39. PUMPING STATION LAYOUT

40. CONVEYANCE
 There are two stages in the transportation of
water
 Conveyance of water from the source to the
treatment plant.
 Conveyance of treated water from treatment
plant to the distribution system.

41. TYPES OF CONDUITS
 Gravity flow system
 Flows freely due to gravity
 Pressure flow system
 closed conduits
 water flows under pressure above the
atmospheric pressure.