4.3.3
Two
Point
Calibration
Note: 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)
Perform a Probe‐Zero.
2)
Apply couplant to the sample piece.
3)
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 display should show some (probably incorrect) thickness
value, and the coupling status indicator should appear steadily.
4)
Having achieved a stable reading, remove the transducer. If the displayed thickness changes from the value shown
while the transducer was coupled, repeat step 3.
5)
Press the
key. The MM (or IN) symbol should begin flashing.
6)
Use the
key and the
key to adjust the displayed thickness up or down, until it matches the thickness of the
sample piece.
7)
Press the
key. The display will flash 1OF2. Repeat steps 3 and 4 on the second calibration point.
8)
Use the
key and the
key to adjust the displayed thickness up or down, until it matches the thickness of the
sample piece.
*you
will
not
see
2OF2
on
display.
9)
Press the
key, so that The M/S (or IN/μS) symbols are flashing. The gauge will now display the sound velocity
value it has calculated based on the thickness values that were entered in step 6.
10)
Press the
key once more to exit the calibration mode. The gauge is now ready to perform measurements
within this range.
4.3.4
Storing
Sound
Velocities
in
Memory
The UTG‐2900 is capable of storing multiple sound velocities to enable the user to quickly check
different known materials.
Example: If you are testing steel at .233 in/us, you can quickly change to one of your stored sound
velocities when you need to test your aluminum, brass, plastic, etc. part.
Power unit on. Press the VEL button until you see
in/us
flashing. Now press the
button to scroll
through the set sound velocities. Find a velocity closest to your material and adjust it to match your material by
pressing the UP or DOWN arrow buttons. Place probe on your part and the gauge will automatically store this velocity
for future use.
4.4
Making
Measurements
When the tool is displaying thickness measurements, the display will hold the last value measured, until a new
measurement is made.
In order for the transducer to do its job, there must be no air gaps between the wear‐face and the surface of the
material being measured. This is accomplished with the use of a “coupling” fluid, commonly called “couplant”. This
fluid serves to “couple”, or transfer, the ultrasonic sound waves from the transducer, into the material, and back again.
Before attempting to make a measurement, a small amount of couplant should be applied to the surface of the
material being measured. Typically, a single droplet of couplant is sufficient.
After applying couplant, press the transducer (wearface down) firmly against the area to be measured. The
coupling status indicator should appear, and a digit number should appear in the display. If the instrument has been
properly “zeroed” and set to the correct sound velocity, the number in the display will indicate the actual thickness of
the material directly beneath the transducer.
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