Gutermann

1. Gutermann Introduction to Correlation

2. General • Please TURN OFF Mobile Phones! • Special requirements for lunch • Smoking • Toilets • Coffee Breaks • Fire procedures • Health & Safety while on site

3. Introduction to Correlation

4. Before we start Tell us about yourself: • Where do work? • What is your Job? • How long have you been doing it? • What have you done in the past? • What would you like to get out of the course? • What are your interests?

5. Agenda 1. Background to Leak Noise 2. Correlator Terminology & Principles 3. Correlator Development 4. Correlator Equipment 5. Setting Up and Getting Started 6. Basic on Site Setup 7. Leak Field Correlation 8. Interpreting Results 9. Extra Features 10. Sources of Error 11. Velocity Check 12. Equipment Fault Checks 13. Other leak detection processes (LLP) 13. TEST !!

6. Background to Leak Noise

7. Background to Leak Noise

8. Different Noise Sources • Leakage • Partial obstruction of pipe bore (foreign object) • Consumption • Pressure reducing valves (PRV’s) • Partially closed valves (throttled or passing) • Close proximity of main to sewer/culvert pipe • Changes in pipe diameter • Water pumping • Electrical interference • Pipe lining

9. Leak Noise Quality • Important Factors - Clarity - Strength • Good Leak Noise - Clear, light & easy to distinguish - Strong & easy to hear • Poor Leak Noise - Dull, muffled & difficult to distinguish - Weak & difficult to hear

10. Mechanical vibration Short section of water filled pipe Pressure wave Rupture Pipe / Rupture with vibration & pressure wave

11. Section of water filled pipe buried in hard backfill High pressure inside pipe Low pressure outside pipe Rupture Water draining away Hard backfill diagram

12. High pressure inside pipe Section of water filled pipe buried in soft backfill Water filled cavity due to collection in backfill Rupture Outside pressure increasing as cavity fills with water Back pressure Soft backfill diagram

13. burst Acoustic noise transfer from a leak in a pipe Energy generated from the leak is transmitted within the pipe through the water energy from the leak is also transmitted through the pipe wall

14. Pressure within pipe is lost Complete rupture Complete rupture diagram

15. Pressure maintained within pipe Small rupture Small rupture diagram

16. DifferentMaterial Types • Steel • Ductile Iron • Copper • Asbestos Cement • Lead • PVC • Polyethylene • Hardest material • Softest material

17. Leak Noise Factors

19. dB 40 dB - 100 dB- Leak found with noise loggers & usually with conventional methods 100 10 dB - 40 dB- Leak found with noise loggers only, correlation generally required 40 10 0 dB - 10 dB- No leaks 0 Leaks on plastic pipes are often found at intensities of 20-40dB

20. Correlator Terminology & Principals

21. Principal of Correlation To obtain a good correlation display, noise MUST be heard at each sensor B A Similar sounds Dissimilar sounds

22. Correlation Formula L = D - (V x Td) 2 L = Leak position (m) (meters) V = Velocity of sound along pipe (m/ms) (meters per millisecond) D = Length of pipe (m) (meters) Td = time delay (ms) (milliseconds)

23. Velocity of Sound Velocity - movement in a specified direction Speed - movement in any direction In practice, for most correlator users, Speed = Velocity Speed / velocity = SOUND WAVEtravelling along a pipe network For all practical purposes the speed of water is not important. Typical water velocity = 2 m/s Typical speed of sound through iron pipe = 1300 m/s

24. Factors Affecting Velocity • Material - metallic (harder materials) are faster; plastics (softer materials) are slower • Size - The larger the pipe diameter, the slower the velocity of sound • Age (internal and external condition) • Repairs (using mixed materials)

25. Time Delay If a leak was exactly midway between the two correlation points, the noise pattern would be identical. If a correlated leak is closer to one sensor than the other, then there is a “Time Delay”(of only a fraction of a second) for noise to reach the furthest sensor.

26. Leak Noise Correlator (LNC) Transmitter Transmitter A B D1 D2 Velocity of + Time delay of leak sound = Precise location leak sound arriving at each sensors of leak in pipe The Principal of Leak Noise Correlation Valve chamber Valve chamber

27. ..and the same with a ‘CORDLESS’ LNC Cordless LNC Transmitter Transmitter Valve chamber Valve chamber A B CORDLESS Transmitters can often be positioned below ground, INSIDE valve chambers, with valve chamber closed But more about that later

28. Correlation Formula D = 100m, v = 1m/ms, Td = 80ms towards ‘A’ Substitute in correlation formula L = 100 - (1 x 80) 2 = 100 - 80 2 = 20 2 = 10m (Transmitter ‘A’) Order of calculation 1. Multiply 2. Subtract 3. Divide

29. Examples L = D - (V x Td) 2 Correlation formula examples L = Leak position (m) V = Velocity of sound along pipe (m/ms) D = Length of pipe (m) Td = time delay (ms) 1. D = 150m V = 1.2 m/ms Td = 60ms (Transmitter A) 2. D = 70m V = 0.6 m/ms Td = 0ms (Transmitter A) 3. D = 300m V = 0.2 m/ms Td = 70ms (Transmitter B) 4. D = 200m V = 0.9 m/ms Td = 6ms (Transmitter A) 5. D = 700m V = 0.11 m/ms Td = 100ms (Transmitter B) 6. D = 80m V = 1.0 m/ms Td = 80ms (Transmitter A)

30. Calculating with the wrong distance If Velocity = 1.28, Time Delay = 28.2 & Distances change from 150, 145, 120m L=150 - (1.28 x 28.2) L=150 - 36.09 L=113.91 Length= 56.95m 2 2 2 L=145 - (1.28 x 28.2) L=145 - 36.09 L=108.91 Length= 54.45m 2 2 2 L=120 - (1.28 x 28.2) L=120 - 36.09 L=83.91 Length= 41.95m 2 2 2

31. Calculating with the wrong velocity If Time Delay = 28.2, Distances 150m & Velocity change from 1.28, 1, 0.4 L=150 - (1.28 x 28.2) L=150 - 36.09 L=113.91Length= 56.95 m 2 2 2 L=150 - (1 x 28.2) L=150 - 28.2 L= 121.8Length= 60.90 m 2 2 2 L=150 - (0.4 x 28.2) L=150 - 11.28 L=138.72Length= 69.36 m 2 2 2

32. Advantages of having the leak in the central position between sensors when unsure of the velocity of the pipe. IF Time Delay = 1.4, Distances 150m & Velocity change from 1.28, 1, 0.4 L=150 - (1.28 x 1.4) L=150 - 1.792 L=148.21Length= 74.10 m 2 2 2 L=150 - (1 x 1.4) L=150 - 1.4 L=148.60Length= 74.30 m 2 2 2 L=150 - (0.4 x 1.4) L=150 - 0.56 L=149.44Length= 74.72 m 2 2 2 The leak position in these examples is closer to one sensor than the other, therefore a larger Td IF Time Delay = 31.3, Distances 150m & Velocity change from 1.28, 1, 0.4 L=150 - (1.28 x 31.3) L=150 - 40.06 L=109.94Length= 109.90 m 2 2 2 L=150 - (1 x 31.3) L=150 - 31.3 L=118.70Length= 59.35 m 2 2 2 L=150 - (0.4 x 31.3) L=150 - 12.52 L=137.48Length= 68.74 m 2 2 2 Calculating with Time Delays

33. Correlator Development Through the Years

34. Leak Noise Correlators - The Early Days Correlators have been around for over 35 years The first ones were very big, heavy and complicated, often filling the entire storage space in a leakage inspectors van

35. The Evolution of Correlators Early correlators.. ..to Palm PDA multi-point digital LNCs

36. Progression Technology began to improve, meaning smaller, quicker, lighter, more portable and more accurate Leak Noise Correlators (LNCs) First came the Aquascan-500 & the early MicroCorr range

37. Gutermann Aquascan-600 Then came newer, smaller correlators such as the Aquascan-600 & MicroCorr-6 More modern, waterproof keyboard input. Hydrophones became available for non-metallic pipeline applications. Small and easily portable

38. Aquascan-600Portable LNC • Peak suppression to eliminate disturbing noise sources • Frequency step analysis • Transmitter battery life 15 hrs • Processor battery life of 6 hrs • User replaceable alkaline battery cells • Single, portable robust ..IP66 enclosure • Multiple materials .. in one pipe section

39. Aquascan-6500 PC LNC • First PC correlator using user ..friendly Windows software • Easy print-out of detailed site ..zzreports and leak positions • Colour display • Multiple correlation modes • Full coherence analysis • Post correlation • Supplied with lap-top PC

40. Aquascan-700 • Simultaneous multi-correlation • Colour touch-screen operation • On screen reporting and ‘sketching’ • of site and leak position & report • Hi-fi sound quality • (FFT - Fast Fourier Transforms) • Frequency Spectrum Analysis (FSA) • Improved data processing speed • Improved filters

41. New cordless ‘Streetworks Act’ Friendly Sensors NEW Replace all this With this 610 ‘cordless’ transmitter Competitors ‘traditional’ style transmitter with separate accelerometer sensor

42. Traditional vs Cordless Sensors NEW Antenna Antenna Carry handle Handle Integrated charger & hydrophone connector Transmitter Accelerometer Headphones Connector 610 ‘cordless’ transmitter Integrated Transmitter, accelerometer & magnetic base Charger Connector Cable Magnet

43. Using Accelerometers Accelerometers detect the sound propagationthrough the pipe wall and are non-intrusive into the network. More difficult applications:- 1. Plastic pipes over 50m on plastic (MDPE is worse than PVC). 2. Weaker performance at low frequencies(Below 75Hz). 3. Long lengths of pipe e.g. over 600m (iron pipe). 4. Large diameter pipes e.g. trunk mains (above 400mm dia).

44. Using Hydrophones • Hydrophones detect pressure waves travelling through the liquid and are INTRUSIVE into the pipeline. • Potential difficulties/problems:- • 1. Ease of access to water. • Damage on hydrant or general water leakage around the hydrant structure. • 3. Hydrophones tend to work better at lower frequencies and over longer distances.

45. Correlator Equipment

46. Correlator Equipment Combined Radio Transmitter(s) and Active Sensors (accelerometers) Portable Central LNC Processor (can also be a lap-top or ‘toughbook’ PC) Headphones or earpiece (not shown) Integrated battery charger (not shown)

47. First line: Pipe parameters Screen contents from top to bottom and quality of correlation Second line: Battery power and strength of the radio signal Note: If the device is being charged, a flash symbol is displayed next to the battery symbol Correlation graph Position of leak (maximum of correlation function) Position of cursor Spectrum (FFT) of signal A – Coherence spectrum – Spectrum (FFT) of signal B Signal strength and filter settings

48. Press key to enter pipe parameters: Select material and diameter and enter length of pipe. Change between the input fields with . Select manual to enter sound velocity instead of material and diameter.

49. If pipe consists of different materials, select ‘Multiple’ Enter a section: Select it with / and press . Discard changes with . Set the new parameters with .

50. Listening Connect the Bluetooth headset to the AQ610. The connection can be made from the headset or from the AQ610. Press to enter the ‘headset’ menu. Change channel with / .