Dr. James ShucksmithPennine Water GroupUniversity of Sheffield

19th May 2011Water Industry Forum

ContentsLeakage detection – Current practicePressure transient based techniquesDevelopment of a prototype leakage detection deviceResults from the Yorkshire Water networkFuture plans

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Year

Leak

age

(Ml/d

ay)

Source : Ofwat, Security of Supply Report 07/08

Leakage levels in England and Wales 

Pinpointing Leaks – Current Practice

Valve open

Valve closed, after time, t

When t = L/c, Full compression)

Decompression

What is a Pressure Transient?

What is a Pressure Transient?Known as Water hammer – A pressure fluctuation in pipeline due to a change in the system (i.e. from valves, pump start‐up etc...)Occur frequently in distribution systemsChange propagates through the system by wave action which travels through pipe at the speed of soundDiscontinuities and dead ends cause reflections

Work on studying pressure transients ongoing topic of at the University of Sheffield.KTP between Yorkshire Water/University of Sheffield in place October 2008-2010 – Leak Detection by use of Pressure Transients

Creating a Detection Device

Hydrant

Valve

Sensor

Electronic Control Box(Battery, Charger, Data Acquisition and Valve

ControlLaptop

(executable file)

U.S.B

Cable

Detection Using Pressure Transients1. Create pressure transient by rapidly closing a valve2. Pressure transient travels down the pipe

3. On contact with a feature, a reflection is created

4. Measure the pressure/time information

5. Filter noise from signal and analyse identify features6. Distance to each feature = time of incoming reflection     speed of wave

LeakFlow Sensor

Speed of wave dependant on pipe material, thickness and diameter

Pressure Transient Example

0.5 1 1.5 2 2.5 3 3.5 40

Time (s)

Pre

ssur

e

Valve Closes

Initial Pressure Surge

Wave propagates through the system

Wave dissipated, system settles at a higher pressure

Data Processing

Raw Data(Pressure/time)

Filtered Data(Pressure/Time)

Analysed Data(Reflection/Distance)

Averaged Result(Reflection/Distance)

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0.005

0.01

0.015

0.02

0.025

Cepstrum Analysis2

Distance (m)

Cep

stru

m A

mpl

itude

(Am

p. *

Tim

e)

Site

Initial Field Tests

Leakage Training Ground Tests

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Ceps

trum

()

Hydrant 1Valve 1

Hydrant 2

Hydrant 3Leak

Valve 2

Flow

Field Tests

Roach Road, Sheffield

62m

28m

Distance (m)

Ave

rage

d C

epst

rum

Aver

aged

C

epst

rum

Aver

aged

C

epst

rum

Distance from hydrant 2 (m)

Distance from hydrant 1(m)

Courts Close, Selby

0.3l/s

Church St, Rotherham

Testing Hydrant

3.15l/s

31m

Leak Point Reflection from end

Status of ProjectThree devices will shortly be used by Yorkshire Water  leakage staff alongside existing techniques

Results of fieldwork fed back for further software optimisation / adaption over different ranges/pipe types

Discussion of commercialisation and development with various interested parties is on goingIn investigation of other uses

Asset identificationPermanent deploymentRemote analysis / plan overlay

Key benefits of techniqueVastly improved accuracy and performance on ‘quiet’ leaks – i.e. plastic mainsUntroubled by background noise (traffic machinery)Direct relation between reflection strength and leak size provides opportunity for resource prioritisationFlexibility of use (single/multiple hydrants)Significant development opportunities in terms of asset identification, network monitoring  

To Conclude.....Existing leakage pinpointing methods are heavily dependant on acoustic techniquesLimited effectiveness of all acoustic devices for quiet leaks (i.e. plastic mains) can result in slow, inaccurate leak pinpointingPressure transient techniques have been shown to offer a entirely new way of pinpointing leaksWith help from manufactures work is now focusing on turning prototype into a commercially viable device

Ghazali, M., Staszewski W.J., Shucksmith, J.D., Boxall J.B, and Beck, S.B.M., ”Instantaneous Phase and Frequency for the Detection of Leaks and Features in a Pipeline System” Structural Health Monitoring (first published online on June 28, 2010), doi:10.1177/1475921710373958

Shucksmith, J.D., Boxall J.B, Seth, A and Staszewski W.J and Beck, S.B.M “Leak detection in a pipe network by cepstrum analysis of pressure transients”(Submitted to the ASCE, Journal of Hydraulic Engineering)

M. Taghvaei, S.B.M. Beck, W.J. Staszewski, “Leak detection in pipelines using cepstrum analysis, Institute of Physics-Measurement Science and Technology”, 17 (2006) 367-372.

M. F. Ghazali, S. B. M. Beck, J. D. Shucksmith, J. B. Boxall and W. J. Staszewski, “Comparative study of instantaneous frequency based characteristics for leak detection in pipeline networks.” (Submitted to Mechanical Systems and Signal Processing)