Calibration To A Known Velocity
This procedure requires that the operator knows the sound-velocity of the material to be
measured. A table of common materials and their sound-velocities is attached.
1.Make sure the
MX-3
is on.
2.Press the
CAL
key to enter calibration mode. If the MM symbol is flashing, press
the
CAL
key again, so that the M/s symbol is 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
MX-3
is now ready to perform measurements.
NOTE
At any time during the calibration procedure (
MM
or
M/s
) pressing the
PRB-0
key will re-
store the tool to the factory default sound-velocity for steel (5.920 m/sec).
To achieve the most accurate measurements possible, it is generally advisable to
always calibrate the
MX-3
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.
Two Point Calibration
This procedure requires that the operator has two known thickness points on the test piece
that are representative of the range to be measured.
1. Make sure the
MX-3
is on.
2. Perform a Probe Zero (see page 8).
3. Apply couplant to the sample piece.
4. Press the transducer against the sample piece, at the first/second calibration
point, making sure that the transducer sits flat against the surface of the sample. The dis-
play should show some (probably incorrect) thickness value, and the Stability Indicator
should have nearly all its bars on.
5. Having achieved a stable reading, remove the transducer. If the displayed
thickness changes from the value shown while the transducer was coupled, repeat step 4.
6. Press the
CAL
key. The
MM
symbol should begin flashing.
7. Use the
UP
and
DOWN
arrow keys
to adjust the displayed thickness
up and down, until it matches the thickness of the sample piece.
8. Press the
PRB-0
key. The display will flash „1OF2“.
9.Repeat steps 3.–7. on the second calibration point. The
MX-3
will now display the
sound-velocity value it has calculated based on the thickness values that were entered in
step 7.
The
MX-3
is now ready to perform measurements.
Scan Mode
While the
MX-3
excels at making single point measurements, it is sometimes
desirable to examine a larger region, searching for the thinnest point.
MX-3
includes a fea-
ture, called SCAN Mode, which allows it to do just that.
In normal operation, the
MX-3
performs and displays four measurements every
second, which is quite adequate for single measurements. In SCAN Mode, however, the
tool performs sixteen measurements every second, but does not display them.
While the transducer is in contact with the material being measured, the
MX-3
is keeping
track of the lowest measurement it finds. The transducer may be „scrubbed“ across a sur-
face, and any brief interruption in the signal will be ignored. When the transducer loses
Operation
MX-3
Manual
Rev:00
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