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Sound Leak Detection PDF Print E-mail
Written by Administrator   
Tuesday, 04 September 2012 23:00

Very valuable resources are getting lost in the damaged pipelines.  Due to water losses, water preparation costs are additionally increased due to over-dimensioned structure of pipeline network (pumps, reservoirs, pipes etc).  Even small cracks on the pipes can already cause high financial losses.  Pipeline damages must be located and repaired fast.  

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 Soun Leak Detection Principle 

To locate damages and malfunctions of pipelines, first of all the sounding method is used.  During water outflow at the damaged location, the sound waves are ensuing in the surrounding soil and transmitted forward together with the water column.  Sound waves of the water column are being transmitted on both sides of the pipeline hitting its walls, and therefore we can discuss the so-called echo of the body sound.


The wider the sound waves are transmitted, the weaker their sound is.  However, there is a point at which water column sound waves are no longer capable of oscillating the pipe material.  The echo of the body (pipeline) can no longer be heard at that point.  In this context, the composition of the soil also plays an important role.  Pipe tightness and material, operating pressure and pipe diameter should also not be discarded.

Sound Types

 Pipeline Echo

Sound waves in the pipeline are being sounded by using a sensitive microphone and instruments at accessible points.  In parallel to that, pipe oscillations can be identified with the sensitive microphone.  Frequency range of these signals is between 500 and 3 000 Hz

 Soil Echo

Soil echo ensues because of the pressure caused by the recurring water hitting the soil and thereby making a sound.  This sound is expanding in funnel shape upward (soil surface) and can be registered with the sensitive microphone.  In this case sound frequency ranges between 100 and 700 Hz.  Frequency levels, which wavelength is lower than the pipe depth, are being severely suppress based on the effects of deeper parts of soil and therefore lower frequencies penetrate the soil surface more easily.  

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Flow Echo

Stronger flow echoes ensue from narrowed places depending on pipeline construction conditions, e.g. at a partly closed valve or pipe constriction due to sedimentation, which generates turbulent flows.  

Sounding methods of damage location are founded on the identification of damages on the basis of sound frequency.  For this method special measurement devices described later in text are being use. The following table gives an overview of sound frequences produced by different conditions in the pipeline:




Outflow through the opening

500 – 800 Hz

Hydraulic head water hammer

20 – 250 Hz

Water circulation and flow

20 – 250 Hz

 Table  - Sound frequency depending on the type of source


Frequencies given in the table have been measured in the vicinity of the location producing the sound.