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© TEA. www.tea.ie 1
Pumping Technology
© TEA. www.tea.ie 2
• Pump Types
• Pump Selection Parameters
• Performance Curves
• Variable Speed
• Motor Efficiency
• Pipe Design
• Control Systems
Agenda
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• Positive Displacement Pump
• Progressive Cavity – Mono or Seepex.
• Rotary Lobe Pump
• Centrifugal Pump
• End suction
• Multi-Stage vertical and horizontal
• Split Case
• Unlike positive displacement pumps , centrifugal pumps deliver a variable flow rate Q (increasing with decreasing head H) when operating at constant speed.
Pump Types
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Progressive Cavity Pump
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How do Progressive Cavity
Pumps work?
• When the rotor and stator
are combined cavities are
created
• As the rotor rotates these
cavities are progressed
through the pump stator
• Two complementary cavities
are formed, as one is finishing
the other is beginning
• This results in an
uninterrupted continuous flow
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Progressive Cavity Pump
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Rotary Lobe Pump
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Rotary Lobe Pump
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End Suction Centrifugal
Pump
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Centrifugal Pump
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• Runs at fixed speed (electrical frequency of
power)
• Flow will be determined by resistance to flow
(head).
• Motor will supply as much or as little power
as is required to maintain fixed speed (within
capabilities).
• Power consumed based on pump curve.
Centrifugal Pump
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End Suction Centrifugal
Pump
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Centrifugal Pump Impeller
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Mechanical Seal
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Multi-Stage Pump
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Horizontal Multi-Stage
Pump
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Split Case Centrifugal
Pump
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Split Case Centrifugal
Pump
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Vertical Multi-Stage Pump
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Submersible Borehole
Pump
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Submersible Sewerage
Pump
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Pump Selection Parameters
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Pump System
Reservoir
Source
Motor (4)
Key components to be dealt with individually:
1. Pump
2. Motor
3. Pipework
4. Rising main
Pump: impellor &
stator only (1)
Pipework
(Pumphouse &
Rising Main) (3)
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Energy in pumping
Motor losses
Real work
Done
Pipe losses
Pump losses
Typical Energy efficiency of a pump set today
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Flow
Flow means the quantity of liquid to pass
across a surface, such as the delivery flange
of a pump or a cross section of a pipe, in a
unit of time.
• Gallons per minute (gpm)
• Litres per minute (I/min)
• Litres per second (I/s)
• Cubic metres per hour (m3/h)
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Head
• Head means height, difference in level or gradient.
• A pump has a flow of 10 litres per second and a
head of 30 metres, this means that the pump is
capable of raising 10 litres of liquid through 30
metres every second.
• The pump will achieve this head no matter what
liquid is being pumped. This means that the pump
will lift water, petrol, mercury, etc. and only the
power demand on the motor will have to be
different.
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• Static Head: This is the vertical height from the
water level at the intake to the highest point to
which the water is to be delivered.
• Friction Head: This is the head generated
through losses generated in the rising main,
suction pipework and valves.
• Counter Pressure: Pressure head requirements
in water softeners, pressure filters, control
valves, etc.
Head
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Friction Head / Head loss
• Head loss is that part of the head, possessed by
the liquid, which is lost in passing through a
pipe, valve or filter.
• This loss is not recoverable as it is lost due to
friction.
• The head loss is proportionately greater as the
speed of the liquid increases.
• So the more the flow is restricted by scaled
pipes, clogged filters, partially closed valves etc.
the greater the head loss will be.
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Pipe Losses
Reservoir
Source
Motor (4)
Real
work
Done
Pipe
losses
Pump
losses
Motor
losses
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Rising Main Friction
Losses
3 KM Rising Main Flow - 60 m³/hr
• 200mm dia. Friction = 0.13m/100m (0.5m/s)
• 150mm dia. Friction = 0.6m/100m (0.9 m/s)
• 100mm dia. Friction = 4.5m/100m (2.1 m/s)
• 200mm pipe = 3.9m (energy cost = €3/day)
• 150mm pipe = 18m (energy cost = €14/day)
• 100mm pipe = 135m (energy cost = €105/day)
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System Curve
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Suction Lift
The Suction Lift calculations includes:
• The vertical height difference from the water level in the
sump to the centre of the pump suction flange.
• Losses in suction pipework and footvalve.
• Flow velocity at pump inlet.
• Liquid vapour pressure.
• Atmospheric pressure
This calculation provides the Nett Positive Suction Head
available from the system. NPSHa
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N P S H a
Pi = Surface pressure of fluid (N/m2)
Pb = Barometric pressure (N/m2)
Pv = Vapour pressure of fluid (N/m2)
ρ = Fluid density (kg/m3)
Ve = Velocity of fluid at pump inlet (m/s)
Ze = Fluid Surface level above pump inlet. (m)
Fe = Friction loss is pipe to pump. (m)
The Pump Manufacturer provides the NPSH required by the
pump. If the NPSHa is less than the NPSHr cavitation will occur.
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Cavitation
• Cavitation is the vapourisation of liquid caused by the
pressure dropping below its vapour pressure at the impeller
inlet.
• As liquid flows from the pump inlet flange into the impellor the
head initially falls as the velocity of the fluid is
increased. This drop in head may be sufficient to cause the
liquid to boil. This results in "cavitation".
• Cavitation is detectable as a rattling noise and results in low
pump efficiency and high risk of damage to the pump.
• To prevent cavitation the NPSH available from the system
must be greater than NPSH required by the pump.
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Pump Efficiency
Reservoir
Source
Motor (4)
Real
work
Done
Pipe
losses
Pump
losses
Motor
losses
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Delivered power
• Delivered power is the power delivered by the pump to the liquid. The value of this power depends upon three factors:
• Flow
• Head
• Specific Gravity of the liquid – i.e. a pump which delivers petrol does less work than when it delivers sulphuric acid, because the specific weights of the two liquids are different.
• The power which the pump consumes is the absorbed power.
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Absorbed or Shaft power
This is the power that the pump absorbs from the motor.
The absorbed power includes:
• Delivered power to the liquid
• Hydraulic losses within the pump
• Friction losses within the pump
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Efficiency
• Pump efficiency is obtained by comparing the power delivered
to the liquid to the power absorbed by the pump.
• For example a pump that is 75% efficient only delivers 75% of
the absorbed power, the remaining 25% is lost within the pump.
• The efficiency of a motor is obtained by dividing its nameplate
power output by the input power consumed from the ESB
sometimes referred to as P1 and P2. The efficiency losses are
made up of heat and iron losses within the motor.
• The overall pump/motor efficiency is calculated by multiplying
both.
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• Water kW = ρ . g . Q . H
• = ρ . Q(m3/hr) x H(m)
367
• Pump input power
= Q(m3/hr) x H(m)
367 x η
Power - Efficiency