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6 Measuring the sound velocity
6
Measuring the sound velocity
6.1
General
Sound velocity measurements are necessary because it is impor-
tant to enter the correct sound velocity for an exact measurement.
The sound velocity values are contained in an internal
table (see
section 8.6.7). The sound velocity data in “pipe data” is, however,
approximate. Furthermore, you may not know the pipe dimension
or the material.
This function requires a source of noise,
for example, an open hydrant,
which produces a clear symbol in the CCF, in other words is
“correlatable”,
which must have a known position,
which must not be positioned in the “middle area” of the mea
-
suring section in order to increase accuracy.
If the measuring section is comprised of several pipe sections
(material or dimension intersections), the sound velocity measure-
ment will produce erroneous results.
6.2
Performing a measurement
The measuring procedure is very similar to a correlation measure
-
ment.
First connect the microphones and radio transmitter as de-
scribed (see sections 2.3).
Activate “Measuring method” “Sound velocity” in the
menu
(see section 8.5).
Select “Pipe data” from the menu and enter the data accord
-
ingly.
When asked about a “man-made leak” you must enter the dis
-
tance of the man-made
leak from microphone 1:
If it is outside of the measuring section and beyond
microphone 1, enter 0 m for the distance.
microphone 2, enter the total length of the measuring section
for the distance, i.e. the „pipe length“.
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