Dakota Ultrasonics DFX-8 plus MANUAL2 - Manual (Page 22)

Dakota Ultrasonics
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8) Finally, press the MEAS key to return to the measurement screen and
begin taking readings.
Known Coating Thickness
When the exact velocity of a coating is unknown, the user has the option of
performing a one point calibration on a sample of the coating with a known thickness
to determine the sound velocity. It would be very handy to carry a set of mechanical
calipers to use in conjunction with the DFX-8 for calibration in the field:
Using a Coating Sample to Calibrate
1) Physically measure a location on a coating sample using a set of calipers or
a digital micrometer.
Important Note: In PECT (pulse-echo coating) mode, the coating sample must
be coupled to metal in order to calibrate successfully. Simply place a drop of
couplant on a piece of metal, lay the coating sample over the couplant on the
metal and proceed to step 2.
2) Apply a drop of couplant on the transducer and place the transducer in
steady contact with the coating (on metal) sample or actual test material. Be
sure that the reading is stable and the repeatability indicator, in the top left