Post on 29-Mar-2022
Centre for Agricultural Engineering
Burdekin Region Workshop 4
Pump Performance CurvesMalcolm Gillies, Michael Scobie, Stephen Attard, Gavan Lamb,
Centre for Agricultural Engineering
Session Objectives
• What does a pump do
• What is a pump performance curve
• Pumps are not created equal
• Pump Speed and impeller diameter
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• A mechanical device which Energy to pipeline flow• not flow or pressure!!!
• They transform input power into hydraulic power
• Turbines have the opposite effect – Transform hydraulic power into output power. e.g. spinning the shaft of a generator
Input Power(motor shaft)
Hydraulic Power (water moving)
What is a Pump?
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Pumps
Rotodynamic Positive Displacement
Centrifugal Special
-Jet-Gas lift-Electromagnetic
Radial flow
Mixed flow
Axial flow
Reciprocating Rotary
-Screw-Piston-Gear-Peristaltic
Piston Diaphragm
(Tyco 2005)
(DavidMarsh Wiki commons)
Pump Classification
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• Describes the relationship between the head (TDH) and discharge (Q) produced for a specific pump configuration• Also called the Head-Discharge Characteristic
• Curve refers to a
• Specific Make & Model
• Constant Speed
• Impeller trim size
• The pump “MUST” operate on this curve
Discharge or Q (L/s)
To
tal H
ea
d o
r T
DH
(m
)Pump
Curve
Pump Curve
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Major difference is how the head varies with Q
Positive Displacement
Q is only a function of pump speed
Rotodynamic
Q is a function of Head
Discharge, Q (L/s)
He
ad
, H
(m
)
Discharge, Q (L/s)
He
ad
, H
(m
)
Positive Displacement vs. Centrifugal
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Major difference is how the head varies with Q
Positive Displacement
Q is only a function of pump speed
Centrifugal
Q is a function of Head
Discharge, Q (L/s)
He
ad
, H
(m
)
Discharge, Q (L/s)
He
ad
, H
(m
)
Positive Displacement vs. Centrifugal
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• (Radial Flow) Centrifugal Pump• High Head, low flow
• Mixed Flow Centrifugal
• Axial Flow• Low Head, High Flow
(Tyco 2005)
(Aust, Pump Manufacturer’s Association 1978)Centrifugal Pumps
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• The shutoff head is the head produced under closed valve conditions
• The duty point is the combination of flow and head the pump is operating at• Also known as operating point
Pump Curve Features
Discharge or Q (L/s)
To
tal H
ea
d o
r H
(m
)shutoff
Head
Pump
Curve
TDH
Duty
Point• The actual duty
point is dictated by the pipeline
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(Tyco -www.southcross.com.au)
Centrifugal PumpOne Speed –Different Impellers
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(Tyco -www.southcross.com.au)
Centrifugal PumpOne Impeller -Different speed
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Giles & Gaskin 180HC Curve(single Stage)
0 10 20 30 40 50 60 700
10
20
30
40
50
60
Flowrate (L/s)
To
tal D
yn
am
ic H
ea
d (
m)
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• The relationship between head and flow in the pipeline
• How much head must the pump deliver for a given flow in the pipe
• Made up of• Static Lift
• End pressure
• Friction loss
• Loss in bends
• Loss in valves
• Loss in diameter changes
• Can be calculated if we know the pipeline specs
System Resistance Curve
Discharge or Q (L/s)
To
tal H
ea
d o
r H
(m
)
Static head
Losses
Pipeline
curve
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• The pump operates at the point where pump curve and pipeline curve intersect.
• If we want a different flow we need to change the pump OR pipeline
Operating Point or Duty Point
Discharge or Q (L/s)
To
tal H
ea
d o
r H
(m
)shutoff
Head
Pump
Curve
Pipeline
curve
Duty
Point
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More losses
Discharge or Q (L/s)
To
tal H
ead
or
H (
m)
Static
HeadPump
Curve
Pipeline
curve
Duty
Point
Valve ½ shut
or Longer pipe
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Decrease losses
Discharge or Q (L/s)
To
tal H
ead
or
H (
m)
Static
HeadPump
Curve
Pipeline
curve
Duty
Point
Decrease
losses
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Bore level has dropped
Discharge or Q (L/s)
To
tal H
ead
or
H (
m)
Static
HeadPump
Curve
Pipeline
curve
Duty
Point
Water level
dropped
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• Iso-efficiency curves• Contour lines of efficiency
• NPSHR lines• Cavitation
• Power curves (estimate of power required)
Other lines on the pump Chart
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Centrifugal PumpEfficiency
Max eff.
This is ONLY pump efficiency. It
does not include the motor
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Pump curves are used in design but can also be useful in other ways
• Someone has completed a performance test and get a duty point as shown. • What does this mean?
Using the pump curve
Discharge or Q (L/s)
To
tal H
ea
d o
r H
(m
)Pump
CurveMeasured
Duty
• Error in Measurement?
• Pump impeller different?
• Pump speed is wrong?
• Pump impeller damaged?
• Cavitation?