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7/22/2019 Module 8 - Pumps for Water Supply 1(Revised)
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Danilo V. Ravina NAMPAP - CEBU 1
MODULE 8
PUMPS FOR WATER SUPPLY
PLUMBING FUNDAMENTALS
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What is a Pump?
Pump is an equipment used to transfer fluid from a
region of low pressure to another region at same or
higher pressure. (PSME Code 1993)
Pump A device or machine that compresses and/or
transports fluids usually by pressure or suction, or both;
may be used to remove water from a construction site orto convey water from one elevation to another. (Harris,
C.M.; Dictionary of Architecture and Construction, 1975)
In about 120 BC someone, probably the Greek mathematician Ctesibius,
invented the first force pump. It had 2 cylinders with single acting pistons,
connected to a single beam so that they delivered an almost continuousstream of water.
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DESIGN OF PUMPS
Data needed to purchase
pumps:
1. Pump Discharge (Q)
2. Total Dynamic Head (TDH)
Pump Discharge or Capacity
of Pump:1. If the pump is used directly to
supply water, the capacity
must be equal to the
maximum hour demand.
2. If the water distributionsystem has a reservoir, the
pump capacity must be equal
to the maximum day demand
Pump Selection:
1. In the absence of electric power
and in cases of isolated small
population, hand pumps are
recommended because of higher
capital, maintenance and
operating costs of diesel or
gasoline engine driven pumps.
2. If the well water depth is 6 meters
or less, use centrifugal pumps(maximum suction lift = 6.00 m).
3. If the well water depth is 6 to 20
meters, usejet pumps.
4. If the well water depth is more
than 20.00 meters, use
submersible pumps orvertical
line shaft turbine pumps.
Pump operating Time = at Least
at least 8 12 hoursDanilo V. Ravina NAMPAP - CEBU 3
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What are the different classifications
of pumps?
The different classifications of pumps are categorized as
follows:
1. As to Operating Principle
2. As to Casing Design3. As to Mounting
4. As to Connection with Driver
(Motor or Engine)
5. As to Construction Materials
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Classification of Pumps as to
Operating Principle:
1. Centrifugal Type
a. Radial Flow
b. Axial Flow
c. Mixed Flow
2. Positive Displacement
Type
a. Reciprocating Piston
b. Reciprocating Plunger
c. Rotary Bladesd. Rotary Roots
e. Screw Types
f. Gear
3. Turbine Type
a. Axial Flow
b. Mixed Flow
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Classification of Pumps as
to Casing Design:
1. Horizontal Split Case
2. Vertical Split Case3. Submerged
Classification of Pumps as
to Mounting:
1. Base Mounted
2. In line Mounted
Horizontal Split Case
Vertical Split Case
Submerged
Base Mounted
In line Mounted
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Classification of Pumps as toConnection with Driver:
1. Flexible Coupled
2. Case Coupled
3. Belt Driven
Classification of Pump as to
Construction Materials:
1. Cast Iron
2. Stainless Steel
3. Bronze
4. Concrete
5. Plastic
6. Fiberglass
Case Coupled
MOTORIMPELLER
PUMP
Belt Driven
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What are the Classifications of Pumps?
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Pumps are generally referred to according to their
principle of action, manner of construction or
method of operation.
Centrifugal Pump(Built by Osborne Reynolds, 1875) A vane orimpeller rotate inside a close-fitting case, draw in liquid at the center and,
by virtue of centrifugal force, throw liquid out through an opening in the
periphery of the case.
1. The higher the speed of rotation, the greater the volume that can bepumped or the greater the head that can be generated.
2. The recommended suction lift is 4.5 meters and should not exceed 6
meters. Therefore, if the well water depth is 6 meters or less, use
centrifugal pump
3. A centrifugal pump cannot operate unless the pump casing is full of
water. For the pump to begin developing a suction at the eye of thepump, the case will have to be filled with water or primed.
4. Care must be taken to ensure that air is not present in the casing and
whenever possible the suction should be of the positive or flooded type.
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Centrifugal Pump:
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What is a Submersible Pump?
Submersible
Pumpis basically acentrifugal pump
complete with electricmotors which are
positioned underwater
in a suitable bored
hole that delivers the
water to the surface.
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What are the important considerations for
accurate Submersible Pump selection?
Well Diameter indicates the size ofthe pump to be installed.
Well Depth indicates the Static WaterLevel, the vertical distance from the surface(Datum Line) to the water level when nowater is being pump.
Pumping Water Level the verticaldistance from the Datum Line to the waterlevel when specified capacity is beingpumped. During the pumping test, PumpingWater Levelis the depth of water when theamount of water withdrawn from the well &the amount of replenishment of water to thewell is equal.
Drawdown the vertical distance or the
difference between the Pumping WaterLeveland the Static Water Level.
Head above Datum indicates theTotal Discharge Head(Static plus Friction)between Datum line & point ofmeasurement.
Pump Capacity volume rate of flowexpressed in cubic meters perhourorliters
per secondto be produced by the pump.
Pump Setting the nominal verticaldistance (in meters) from Datum to thedischarge pipe connection at the pump.
Water Composition make-up of thewater to be pumped.
Type of Drive the specification of theavailable power source (single phase or 3phase)
Allowable Motor Overloadpercentage of rated motor main plate power(in kilowatts or horsepower) that will bepermitted to be used.
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WellDe
pth
Discharge Pipe
Well Diameter
PumpSetting
Drawdown
Submersible Pump
Submersible Pump:
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Positive Displacement Pumps:
Reciprocating and Rotary
Reciprocating PumpA pump which operates with a to and fromotion. The different types of Reciprocating Pump are:
1. Lift Pump The simplest of the reciprocating pump and consists of apiston moving up and down in a cylinder or barrel.
A Lift Pump cannot be used to raise water above 7.50 to 8.50 meter atnormal atmospheric pressure (101 kPa) due to:
a. Loss of efficiency in the pump
b. Friction in the intake pipe
c. Impossible to obtain a perfect vacuum
2. Piston or Plunger Pump A plunger is driven backwards &forwards, or up & down by a mechanical working head.
3. Deep well Piston Pump When water is more than 7.50 metersbelow the ground, it is virtually necessary to place the pump in or near thewater in the well and pump from there. Water is forced up the drop pipeand out into the delivery pipe.
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A LIFT PUMP / HAND PUMP
START OF UPSTROKE
FOLLOWING
DOWNSTROKE
NEXT UPSTROKE
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The Working Cycle of a Piston Pump
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A Deep Well Piston Pump
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What is a Diaphragm Pump?
A Diaphragm Pump is a displacement pump in which a flexible diaphragm
replaces the piston in other displacement pumps. The diaphragm is of
leather or heavy gauge rubber. The upward movement of the diaphragm
has the same effect as the upward movement of the piston; the outlet valve
closes & the inlet valve opens & admits water. The downward movement of
the diaphragm causes the inlet valve to close & water is forced into thedischarge pipe.
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What is a Rotary Pump?
A Rotary Pump is used primarily as a source of fluid power in hydraulicsystem. It continuously scoops the liquid from the pump chamber.
It is classified with respect to the impelling element as:
1. Gear Type
2. Vane Type3. Piston Type
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What is a Jet Pump?
A Jet Pump is a pumpconsisting revolving impeller in the
pump housing which forces water
down a pressure line to an ejector
assembly below water level. This
ejector consists of a nozzle whichdischarges the water into a
constricted throat. This throat
leads from a suction pipe. This
arrangement permits energy of a
high pressure fluid to be converted
into a high velocity fluid.
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What is a Hydraulic Ram or Ram
Pump?
Hydraulic Ram uses the energyof falling water to raise a smaller
quantity of water to greater
heights. It is a pump in which the
power generated from flowing in
an enclosed pipe is used to raisepart of the water to a height above
that from which the flow began.
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What is the Pump Performance
Curve?
The characteristic curve of apump describes the factorsthat affect its performance.They are usually expressedgraphically with the rate ofdischarge (Q) as abscissa &other factors plotted asordinates, such as the Head(H), & the Net PositiveSuction Head (NPSH). Allpump manufacturers supplyperformance characteristic
curves for their pumps whichindicate how the pumpcapacity varies withdischarge pressure orsuction pressure.
Sample of Pump Performance Curve
Source: IBARRA
PUMPS
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Source: GRUNDFOS
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Duty Point & Pump Efficiency
Source: GRUNDFOS
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NET POSITIVE SUCTION HEAD (NPSH)
Low pressure at the suction
side of a pump can
encounter the fluid to startboiling with
reduced efficiency
cavitation
damage
of the pump as a result.
Boiling starts when the
pressure in the liquid is
reduced to the vapor
pressure of the fluid at theactual temperature.
To characterize the potential for boiling and cavitation, the difference
between the total head on the suction side of the pump (close to the
impeller) and the liquid vapor pressure at the actual temperature,
can be used
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Available NPSH (NPSHa)The Net Positive Suction Head made available the suction system for the
pump is often named NPSHa The NPSHa can be determined during design
and construction, or determined experimentally from the actual physical
system.NPSHa : The Pump is Above the TankIf the pump is positioned above the tank, the elevation (he) is
positive and the NPSHa decreases when the elevation of the
pump increases.
At some level the NPSHa will be reduced to zero and the fluid
starts to evaporate.
NPSHa: The pump is Below the TankIf the pump is positioned below the tank, the
elevation (he) is negative and the NPSHa
increases when the elevation of the tank
decreases (lowering the pump).
Ii is always possible to increase NPSHa by
lowering the pump (as long as the major and
minor head loss due to longer pipe do notincrease it more. This is important and it is
common to lower the pump when the pumping
fluids close to evaporation temperature.
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Required NPSH (NPSHr)
The NPSHr as the Net Positive Suction Head as required by the pump
in order to prevent cavitation for safe and reliable operation of the
pump.
The required NPSHr for a particular pump is in general determined
experimentally by the pump manufacturerand a part of the
documentation of the pump.
H d l t th t f t b
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How do we select the type of pump to be
used?PUMP
CAPACITYDEPTH OF WELL
0 to 8.00 m 8.00 to18.00 m
18.00 to27.00 m
27.00 to46.00 m
46.00 m andover
1,200 to
2,400 LPH(300 600 GPH)
Submersible
Pump
Jet Pump
Piston Pump
Submersible
Pump
Jet Pump
Deep Well
Reciprocating
Pump
Submersible
Pump
Jet Pump
Deep Well
Reciprocating
Pump
Jet Pump
Deep Well
Reciprocating
Pump
Submersible
Pump
Jet Pump
Deep Well
Reciprocating
Pump
Submersible
Pump
2,400 to
4,500 LPH(600 1200 GPH)
Submersible
Pump
Jet Pump
Plunger Pump
Submersible
Pump
Jet Pump
Submersible
Pump
Jet Pump
Submersible
Pump
Jet Pump
Submersible
Pump
Jet Pump
Over 4,500
LPH(over 1200 GPH)
Submersible
Pump
Jet Pump
Plunger Pump
Submersible
Pump
Jet Pump
Submersible
Pump
Jet Pump
Submersible
Pump
Submersible
Pump
Pump Selection Rule of Thumb: 1. If the well water depth is 6 meters or less, use Centrifugal Pump.
2. If the well water depth is 6 to 20 meters, use Jet Pump.
3. If the well water depth is more than 20 meters, use Submersible Pump or
Vertical In-Line Shaft Turbine Pumps.
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END OF PRESENTATION