Centre for Agricultural Engineering Burdekin Region

Centre for Agricultural Engineering

Burdekin Region Workshop 4

Pump Performance CurvesMalcolm Gillies, Michael Scobie, Stephen Attard, Gavan Lamb,


Session Objectives

• What does a pump do

• What is a pump performance curve

• Pumps are not created equal

• Pump Speed and impeller diameter


• 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?


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


• 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


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


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


• (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


• 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


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


(Tyco -www.southcross.com.au)



Centrifugal PumpOne Speed –Different Impellers



Centrifugal PumpOne Impeller -Different speed



Centrifugal PumpMixed Flow



Centrifugal PumpMixed Flow


Turbine Pump Giles & Gaskin 180HCTDH

Q


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)


• 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


To

tal H

ea

d o

r H

(m

)

Static head

Losses

Pipeline

curve


• 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


To

tal H

ea

d o

r H

(m

)shutoff

Head

Pump

Curve

Pipeline

curve

Duty

Point


More losses


To

tal H

ead

or

H (

m)

Static

HeadPump

Curve

Pipeline

curve

Duty

Point

Valve ½ shut

or Longer pipe


Decrease losses


To

tal H

ead

or

H (

m)

Static

HeadPump

Curve

Pipeline

curve

Duty

Point

Decrease

losses


Bore level has dropped


To

tal H

ead

or

H (

m)

Static

HeadPump

Curve

Pipeline

curve

Duty

Point

Water level

dropped


• Iso-efficiency curves• Contour lines of efficiency

• NPSHR lines• Cavitation

• Power curves (estimate of power required)

Other lines on the pump Chart


Centrifugal PumpEfficiency

Max eff.

This is ONLY pump efficiency. It

does not include the motor


Centrifugal PumpQ = 30L/s what is the efficiency


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


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?


Q = 60 L/s TDH = 20m ???

Smaller dia? Cavitation?


Q = 70 L/s TDH = 25m ???

Impossible!!!!!

Documents

Centre for Agricultural Engineering Burdekin Region