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FEATURE
in 2007 as its water leak detection equipment supplier. That
equipment is today used by the likes of Rand Water Board
and Joburg Water, he says. Sewerin specialises in gas and
water leak detection.
Speaking at the same event, Sewerin export manager
Christian Scheepers says, “Leak detection requires a
combination of skilled operators and state-of-the-art
equipment to locate a hidden leak. With our array of
equipment, methods and techniques, we are able to locate
almost any leak across all industries.”
He describes two methods of water leak detection:
1. Correlation:
• A leak in a pipe under pressure creates noise that
travels along the pipe, its contents, and through the
surrounding ground
• Two highly sensitive microphones are attached to the
leaking pipe
• The sound from the leak takes longer to travel to the
microphone furthest from the leak
• The correlator uses the ‘time delay’ to pinpoint exactly
where the leak is situated
• After correlation the indicated position should be
checked by top sounding using an acoustic listening
device
2. Acoustics
• When a pressurised pipeline leaks, the water literally
gushes or pushes out of the crack or damaged pipe
into the surrounding ground
• The pipe material vibrates at the leakage point
• These vibrations are transmitted by the pipe and can
even be noticed at distant contact points, for example
fittings
• This is known as structure-borne sound and is made
audible by an acoustic listening device
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Sewerin has a range of products in each category,
ranging from hand-held to mobile. The SeCorrPhon AC
200 is a multifunctional leak detector offering three
functions in one: pre-location, pinpointing and correlation.
“The combination of these processes in one system
allows you to locate the leak regardless of the ambient
conditions. With just a few finger strokes, you can quickly
and easily switch between the various applications.”
The Aquaphon system provides electro-acoustic
water leak detection. “The A 50 receiver and various
microphones make the pre-location and pinpointing of
leaks possible. When both microphone and headphones
are attached the device boasts impressively high
reproduction quality. The display helps by visualising the
noises to provide reliable, differentiated evaluations,” says
Scheepers.
High level of skill required
“For pre-location: with steel pipes, the sound recorded
by the system identifies the size of the leak – it increases
closer to the leak and decreases further from the leak. With
plastics pipes the noise intensity does not carry as far. The
system searches for a noise from the ground microphone. If
you want to find a water leakage with a ground microphone,
it needs to have a noise. When you are searching paved
surfaces, the microphone picks up every other noise too, so
it requires skill and setting adjustments to exclude the birds
singing,” says Scheepers.
Pohorille says that SALD has developed a leak detection
simulator in the surrounding lawns of its premises with as
many as 13 leaks for trainees to practise on and locate, and
include a range of five or six different pipe materials from
galvanised steel to HDPE. “Trainees typically start out feeling
overwhelmed by the variety of different sounds seemingly
coming from every direction, and they slowly learn to
differentiate sounds and train their ear to distinguish a leak
from a car driving by.”
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April 2020 Volume 26 I Number 02