Elcometer CG30 Operating Instructions Manual page 11

5.2.1 One-point calibration
This procedure requires a sample piece of the material to be measured, the exact thickness of
which is known, e.g. from having been measured by some other means.
1. Switch on the gauge.
2. Set the zero point of the gauge - see "Transducer - Zeroing" on page 8.
3. Apply couplant to the sample piece.
4. Press the transducer against the sample piece, making sure that the transducer is flat against
the surface of the sample. The display should show some (probably incorrect) thickness value,
and nearly all the bars of the stability indicator should be illuminated.
5. 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 and 4.
6. Press the CAL key. The MM (or IN) symbol should begin flashing.
7. Use the UP and DOWN arrow keys to adjust the displayed thickness up or down, until it
matches the known thickness of the sample piece.
8. Press the CAL key again. The M/s (or IN/µs) symbols should begin flashing. The gauge is now
displaying the sound-velocity value it has calculated.
9. Press the CAL key once more to exit the calibration mode.
The gauge is now ready to perform measurements.
5.2.2 Two-point calibration
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. Set the zero point of the gauge - see "Transducer - Zeroing" on page 8.
2. Apply couplant to the sample piece.
3. Press the transducer against the sample piece, at the first calibration point, making sure that
the transducer is flat against the surface of the sample. The display should show some
(probably incorrect) thickness value, and nearly all the bars of the stability indicator should be
illuminated.
4. Having achieved a stable reading, remove the transducer.
If the displayed thickness changes from the value shown while the transducer was coupled,
repeat steps 3 and 4.
5. Press the CAL key. The IN (or MM) symbol should begin flashing.
6. Use the UP and DOWN arrow keys to adjust the displayed thickness up or down, until it
matches the thickness of the sample piece.
7. Press the PRB-0 key. The display will flash 1OF2.
8. Repeat steps 3 to 6 on the second calibration point.
9. Press the CAL key again. The M/s (or IN/µs) symbols should begin flashing. The gauge is now
displaying the sound-velocity value it has calculated.
10. Press the CAL key once more to exit the calibration mode.
The gauge is now ready to perform measurements within this range.
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