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If the gauge is not set to the correct sound-velocity, all of the measurements the gauge makes will
be erroneous by some fixed percentage.
Note: The calibration procedures for the flaw detector and thickness gauge are different. The flaw
detector does not use the same probe zero technique as the thickness gauge so for best thickness
reading accuracy in flaw mode follow this guide carefully.
There are three methods of calibrating your gauge:
K
NOWN MATERIAL CALIBRATION
stored in the gauge. After you have selected the material, you should check and if necessary adjust
the zero value - see page 30 making this the preferred calibration method.
K
NOWN VELOCITY CALIBRATION
directly into the gauge. After you have selected the sound-velocity of the material, you should check
and if necessary adjust the zero value - see page 30.
K
NOWN THICKNESS CALIBRATION
see page 30. The zero value is set automatically during this procedure.
For the highest measurement accuracy use the known thickness calibration, as this takes into
account variation in material composition, temperature and a variety of other factors.
15.3 KNOWN MATERIAL CALIBRATION
If the material velocity is unknown, and a sample thickness cannot be taken from the material, you
can choose a material type from a list stored in the gauge. For each material stored in the list there
is a corresponding longitudinal velocity value and a shear velocity value.
Note: In order to display the chart containing the shear wave velocities, the TRIG mode must be
enabled - see See "TRIG - Trigonometry Mode" on page 36.
Note: These velocities will not always be an exact representation of the material being tested. Use
these values only if a close approximation is acceptable.
1. Press MENU/CAL/MAT and then press ENTER
2. Scroll through the material list until the appropriate material is highlighted.
3. Press ENTER to choose the material type, then press OK.
The material velocity and zero value are displayed in the CAL menu.
4. Press MEAS to return to the measurement screen.
5. Measure a calibration standard and, if necessary, adjust the zero value until the material
thickness value matches the thickness of the calibration standard - see "Manually Adjusting
the Zero Value" on page 30.
15.4 KNOWN VELOCITY CALIBRATION
If the material velocity is known, you can enter the velocity value directly into the gauge. A list of the
sound velocities of common materials is given at the end of this instruction manual.
1. Select MENU/CAL/VELOCITY.
2. Press ENTER to display the Digits Edit Box.
3. Use the navigation buttons to adjust the value.
4. Press OK to set the velocity and return to the menu screen, or ESC to cancel.
The material velocity and zero value are displayed in the CAL menu.
5. Press MEAS to return to the measurement screen.
29
: The material you are measuring is selected from a list of materials
: The sound-velocity of the material being measured is entered
: The gauge is calibrated by setting it to two known thicknesses -
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