Aktek AT300 Manuale d'uso - Pagina 9

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4.3 Sound Velocity Calibration

In order for the gauge to make accurate measurements, it must be set to the correct

sound velocity for the material being measured. Different types of material have different

inherent sound velocities. 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. The

One-Point calibration is the simplest and most commonly used calibration procedure

optimizing linearity over large ranges. The Two-point calibration allows for greater accuracy

over small ranges by calculating the probe zero and velocity.

Note: One and Two point calibrations must be performed on material with the paint or

coating removed. Failure to remove the paint or coating prior to calibration will result in a

multi material velocity calculation that may be different from the actual material velocity

intended to be measured.

4.3.1 Calibration to a known thickness

Note: This procedure requires a sample piece of the specific material to be measured, the

exact thickness of which is known, e.g. from having been measured by some other means.

1) Perform a Probe-Zero.

2) Apply couplant to the sample piece.

3) Press the transducer against the sample piece, making sure that the transducer sits flat

against the surface of the sample. The display should show some 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 to activate the calibration mode. The MM (or IN) symbol should begin

flashing.

6) Use the

key and the

matches the thickness of the sample piece.

7) Press the

key again. The M/S (or IN/μS) symbols should begin flashing. The gauge

is now displaying the sound velocity value it has calculated based on the thickness

value that was entered.

8) Press the

key once again to exit the calibration mode and return to the

measurement mode. The gauge is now ready to perform measurements.

4.3.2 Calibration to a known velocity

Note: 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 can be found in

Appendix A of this manual.

1) Press the

key to activate the calibration mode. The MM (or IN) symbol should begin

flashing.

2) Press the

key again, so that The M/S (or IN/μS) symbols are flashing.

3) Use the

key and the

matches the sound velocity of the material to be measured. You can also press the

key to switch among the preset commonly using velocities.

4) Press the

key to exit from the calibration mode. The gauge is now ready to perform

key to adjust the displayed thickness up or down, until it

key to adjust the sound velocity value up or down, until it