User's Manual

Sound velocity measurement
88
12.2 Velocity measurement in Offline measurement mode
12.2.1 Introduction
The Velocity measurement function compares the measuring values of three sensors
which have recorded a shared noise. As a result, the following applications are possible:
Application options
Determining the sound velocity
in the pipe
(for an unknown pipe material)
Determining the position of a leak
(despite unknown pipe material)
The actual sound velocity in the pipe is
calculated.
This value can then be adopted for the
pipe section being analyzed as a pipe
parameter.
The correlation curve will be updated on
this basis.
The distance from a certain measuring
point to the leak position is calculated.
The following conditions must be met in order to determine sound velocity or the leak
position:
• A measurement (night or instantaneous measurement) with at least 3 sensors has
been performed.
• The measured data has been read and saved with the Correlator.
• Between the three considered sensors exists a clearly perceptible source of noise.
(The louder the noise, the lower are the negative effects of any potential
interference on the result of the sound velocity calculation).
• The lengths of the pipe sections between the measuring points must be known.
• The measuring points and sound source must be arranged as shown on the
following picture.
There must be one sensor „in front of“ the sound source (Position 1).
There must be two sensors “behind” the sound source (Positions 2 and 3).
Requirements
Source of noise
Distance
Position 2
Position 1
Position 3
Distance