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Now the unit has detected the initial error factor and will use it to compare all
subsequent measurements. When zeroing, the instrument will always use the sound
velocity of the built-in zero plate, even if other values have been previously entered to
make actual measurements.
Although the last zero setting is saved, it is recommended that it be carried out again
each time the unit is switched on, even if a different probe is used. This will ensure that
the unit is always set correctly. Pressing the
5.4 Sound velocity
In order to be able to make exact measurements, this must be adjusted to the speed
of sound of the corresponding material. Different materials have different sound
velocities.
If this is not done, all measurements will be faulty by a certain percentage. Single point
calibration is the most common way to optimise linearity over a long range. Two-point
calibration allows higher accuracy at a shorter range by calculating the zero setting
and the speed of sound.
Note: For single-point and two-point calibrations, ink or coating must be removed
in advance. If this is not done, the calibration result will consist of a kind of "multi-
material sound velocity" and will certainly not be the same as the actual material to be
measured.
5.4.1 Calibration with known material thickness
Note: This procedure requires a sample of the material to be measured, the exact
material thickness of which, e.g. on any
species was measured before.
1. The zero setting is made.
2. The sample material is provided with coupling gel.
3. The measuring probe is pressed onto the piece of material. A material thickness
value can now be read on the display and the coupling symbol appears.
4. As soon as a stable reading value is reached, the measuring probe is lifted off
again. If the thickness of the material just detected changes from the value that
existed during the coupling, step 3) must be repeated.
5. The and
keys
(that of the material pattern).
6. The key
is pressed and the calculated sound velocity value is displayed on the
basis of the material thickness that was previously saved.
7. To exit the calibration mode, press the
be taken.
12
can now be used to adjust the required material thickness
key cancels the current zero setting.
key. From now on measurements can
TU_US-BA-e-2020
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