PR-8
2
Sonic Tester
15
Calibration to a known velocity
NOTE: This procedure requires that the operator know the sound-
velocity of the material to be measured. A table of common
materials and their sound-velocities can be found in
Appendix C
.
1) Make sure the
PR-8
2
is on.
2) Press the
CAL
key to enter calibration mode. If the
IN
(or
MM
)
symbol is flashing, press the
CAL
key again, so that the
IN/
s
(or
M/s
) symbols are flashing.
3) Use the
UP
and
DOWN
arrow keys to adjust the displayed velocity
up or down, until it matches the sound-velocity of the material to be
measured.
4) Press the
CAL
key once more to exit the calibration mode. The
PR-8
2
is now ready to perform measurements.
NOTE:
At any time during the calibration procedure (
IN
,
MM
,
IN/
s
,
or
M/s
flashing in the display), pressing the
PRB-0
key will restore the tool to
the factory default sound-velocity for steel
(0.233 IN/
s).
To achieve the most accurate measurements possible, it is generally
advisable to always calibrate the
PR-8
2
to a sample piece of known
thickness. Material composition (and thus, its sound-velocity) sometimes
varies from lot to lot and from manufacturer to manufacturer. Calibration to
a sample of known thickness will ensure that the tool is set as closely as
possible to the sound velocity of the material to be measured.
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