Elcometer 205 Operating Instructions Manual page 22

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6.2 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 "Setting the zero point (probe-zero)" on page 16.
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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