Danatronics, Corp.
26
Velocity and Zero Calibration
If you have a test step block of known thicknesses but unknown material, then you can
calibrate the velocity and zero of the sound in the unknown material by measuring the
time of flight from the main-bang to the first back echo for the thinner step and the
thicker step.
To perform a Velocity and Zero calibration, follow these steps:
1. Power on the gage.
2. Use the up and down arrow keys to select your transducer, and then press the
Menu/OK key.
3. Press Menu/OK key.
4. Use the up and down arrow keys to select the Calibration option.
5. Press the MENU/OK key.
To proceed with the calibration, follow the instructions below:
1. Place couplant on the surface of a 5-step test block.
2. Couple the transducer to the material. A similar screen to the one shown below
will appear:
Cal screen
3. While measuring the thinnest step, press the F2 – ZERO key and then use the up
or down arrow keys to scroll the thickness value number to the known thickness
4. Then press the F1 - CAL key
5. While measuring the thickest step, select F3 - VEL key.
6. After pressing the F3 key, you can take the transducer off the test block. If the
displayed measurement is different than the known value of the step, use the up
or down arrow key to adjust the displayed value to the known value of the step.
7. Press the MENU/OK key to perform the calibration. For a few seconds in the
top left hand corner, the calculated acoustic sound speed will be displayed.
Note: This process can be reversed by performing a velocity first and zero second as
long as you enter the known thickness each time. This procedure is when the displayed
user is set to left hand operation; see display settings; see section 4. The gage will
briefly display the calibrated zero value and then return to Measure mode.
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