phase II+ UTG-2800 - Sound Velocity Calibration

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At this point, the instrument has successfully calculated its internal error factor, and will compensate for this

value in any subsequent measurements. When performing a “probe zero”, the instrument will always use the

sound velocity value of the built-in probe-disc, even if some other velocity value has been entered for making

actual measurements. Though the instrument will remember the last “probe zero” performed, it is generally a

good idea to perform a “probe zero” whenever the gauge is turned on, as well as any time a different transducer

is used. This will ensure that the instrument is always correctly zeroed.

Press

while in probe zero mode will stop current probe zero operation and return to the measurement

mode.

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