Leak detection is elementry
Radcom Technologies explains how its new Soundsens system can improve and simplify leak location by combining noise logging and leak noise correlation in a single process.
The water industry in England and Wales is giving itself a well-earned pat
on the back. With leakage reduced by 37%, enough to supply 12.5M people, things
have come a long way since the ‘dark days’ of the early 1990s.
Add to this Ofwat’s softening view of the need for mandatory leakage targets
for most companies and some might say that perhaps the pat on the back is being
Decade of change
At least one long-standing issue of consensus remains constant – waste is a
bad thing. Whether the waste is water leaking into the ground or money spent
on locating difficult to find leaks, depends on your perspective. Whatever your
point of view, there is no doubt that the science of leakage management has
substantially improved in the last decade. Since privatisation, the creation
of thousands of DMAs has enabled water companies to handle network losses in
manageable chunks. In parallel with this, leakage detection and location technologies
have developed rapidly.
In the mid-1990s a water company facing a large disparity between its reported
leakage and its target might have contemplated region-wide deployment of noise
loggers, devices that register noise anomalies in pipes and thus give an indication
of local leakage. However, such a scatter-gun approach would be considered overkill
So where are we with leakage detection technology? Most water companies no
longer routinely carry out step-testing, the process of systematically closing
distribution valves to localise a leak, thanks, in part, to the targeted rather
than widespread use of noise loggers. They are a powerful tool, but do not do
enough to complete the job. Correlation teams are still required in most companies
to convert a localised leak into a pinpointed leak. Thus there is a three-step
process employed by most water companies. Firstly, an increase in minimum night
flow is detected by a DMA flow data logger, which probably indicates the presence
of a leak. Next, the leak is localised to an area using noise loggers. Last,
a specialist team travels to the area to accurately pinpoint the location of
the leak using a conventional correlator system.
Although this approach works, its efficiency is limited by two factors. The
first of these is that many water companies have struggled to fully justify
the cost of adding telemetry to network data loggers. Using lower cost data
loggers, which have to be manually downloaded, results in a significant time
delay between when the burst occurs and when the data from the relevant logger
is collected and analysed. Secondly, there is an additional delay between the
deployment/collection of noise loggers and the arrival of the correlator team.
This is further exacerbated in some companies because the noise logger activities
and the correlator activities have been outsourced to separate, often competing,
One of the equipment suppliers to the leakage industry, Radcom Technologies,
suggests that there is a way to substantially improve the efficiency of the
process. Radcom was one of the companies that pioneered DMA monitoring and network
data logging in the 1980s, and is now keen to extend its role in leakage management
to encompass detection and pinpointing as well.
Radcom believes the current method of leak location can be radically improved
and simplified by combining noise logging and leak noise correlation into a
The system developed for this process, Soundsens, is already in use at many
water companies and is being trialled at several others.
Dr Gurch Chana, technical director and co-founder of Radcom described the system.
“The Soundsens approach is based on the deployment of highly sensitive
and accurate loggers, called ‘pods’. The pods, which are time synchronised,
record sound in short bursts lasting a few seconds. The recording is repeated
multiple times to separate genuine use from suspected leakage.” The duration
of recording, the number of recordings and the dwell time between each recording
is programmable and depends upon the pipe material in question, whether the
test is taking place during the day or at night and whether the pipework being
tested is a trunk or distribution main.
The pods have at their heart an advanced digitally amplified accelerometer,
developed in conjunction with Southampton University, which is capable of detecting
lower levels of sound than can be expected from conventional designs, which
simply correlate sound velocity between two points.
However, the company claims that the key aspect of Soundsens is the way that
the data recorded by the pods is then handled, as Chana continued, “The
data from each pod is transferred to a laptop, where a layout of the pipework
is graphically drawn using either GIS data or as a simple sketch. The layout
enables the software to both link and take into account the spatial relationship
between the pods.”
Once the layout is complete, the software uses proprietary algorithms to amplify
the sound and filter out anomalies. Correlation takes place between each pod
in the array and all of the others. The company says that this process, called
cross-correlation, is unique to the Soundsens system and enables greater certainty
in pin-pointing leaks as it discerns leak noise profiles from other water sounds.
Any leaks are pin-pointed on the pipe layout diagram, tabulated and ranked
in order of probability. The software will also show any correlations that should
be subjected to further investigation. To help with this, the operator can listen
to the sound using the software’s audio feature. The data files can then be
stored for transfer or use at a later date.
The system has already won plaudits. At the IWEX 2001 Innovations Awards, Soundsens
received the highly commended accolade in the measurement and instrumentation
Water companies using Soundsens are reportedly having success with the system
in situations that would normally be difficult for leak noise correlators. In
particular, Soundsens has recently found leaks on trunk mains in the Wessex
Water region and on long length MDPE distribution mains in the Anglian Water
Technology alone cannot answer all of the water industry’s questions about
leakage. However, developments that improve efficiency and save time and money
will help to reduce water loss and go some way to reducing leakage, even if
the remaining questions mean that such a reduction is measured in relative rather
than absolute terms