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symbol illuminated, and the main indicator will show the ultrasound velocity value
(Fig. 9).
4) Using
matches the actual (true) ultrasound velocity of the material to be measured.
5) Press
6) The thickness gauge is now ready to perform measurements.
Note - After the calibration is completed, the ultrasound velocity value will be
saved to the memory of the thickness gauge, and will be used for further
measurements.
4.8 Thickness gauge calibration at an unknown ultrasound velocity ("One point
calibration")
Note - For the thickness gauge to perform accurate measurements, the velocity
of ultrasonic waves in the material of a test object should be set up correctly.
Since the material composition (and thus, its ultrasound velocity) may vary from
lot to lot and from manufacturer to manufacturer, the calibration to a sample of
known thickness made of the same material as a test object will ensure the most
accurate measurements.
For the calibration to a known thickness, please perform the following actions:
1) Plug an appropriate transducer into the thickness gauge using the
connecting cable.
2) Switch the thickness gauge ON by pressing
3) Carry out zero calibration in accordance with para 6.6.
4) Press the transducer against the sample of a known thickness prior wetted
with couplant, making sure that the transducer sits flat against the surface of the
sample. The display should show some (probably incorrect) thickness value, and the
Stability Indicator should have more than a half of its vertical bars on.
and
keys, adjust the displayed velocity up or down, until it
key once again to exit the calibration mode.
Fig. 9
button.
18
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