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 When
a leak detection test indicates a breach in a pressurized
underground pipeline, the Vista PALSystem offers the
latest-generation technology for locating the leak.
In a new twist on acoustic technology, the PALSystem
uses a unique approach to signal processing that is
based on coherence analysis. Other acoustic systems
rely on traditional correlation-based methods, which
typically have produced mediocre results. The PALS,
which is gaining great commercial recognition, has regularly
outperformed other acoustic methods by a wide margin.
The PALS can be used on any underground pipeline system
that can accommodate the placement of sensors at intervals
along its length. Points of access to the pipeline,
such as valve pits or aboveground manifolds, can be
as far apart as 500 linear feet. The PALS has been used,
for example, on transfer lines at bulk storage facilities
and on airport hydrant fuel systems. Noisy, active environments
do not impact the performance of the PALS.
The PALS is a portable passive-acoustic system comprised
of three acoustic sensors, three small pre-amplifiers,
and a portable computer equipped with a data acquisition
card. Each sensor measures the acoustic signal generated
by the turbulent flow through a hole in the pipeline.
A leak location measurement can be made in as little
as 2 to 5 minutes.
The
acoustic signal generated by any leak that might be
present between the "Ref" (reference) and
"Pos" (position) sensors is picked up and
transmitted to the computer via the pre-amplifiers;
the speed at which the acoustic signal is propagating
through the pipeline is measured in the region between
the "Vel" (velocity) and Ref sensors, which—unlike
Ref and Pos—do not bracket the leak. For the leak
to be correctly located, the distances between the sensors
must be known, since the measurement made by the PALS
determines the location of the leak relative to the
reference sensor.
Testing Services
Vista offers testing services
conducted with its PALSystem.
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