Cygnus M3-DIVE, Руководство по эксплуатации

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Cygnus DIVE Operating Manual M3-DIVE-M-ENG_Iss9.docx
Page 44 of 117
Now although the gauge is still correctly measuring 12.5mm you
can see the echo pulses from the bottom of the blind hole
(arrowed).
In practice if you see smaller peaks between the larger peaks it
could be indication of pits or flaws inside the material you are
measuring. By moving the probe around and observing the A-scan
you may be able to identify an area with better, more distinct
ultrasound echo pulses.
If the echo pulses from the pit or flaw obscure the pulses from the
material back-wall the gauge may not be able to determine a
Multiple Echo thickness measurement, the A-scan below shows a
mixture of echo pulses that are spaced irregularly and as a result
no thickness measurement has been located;
Uneven echo pulses from multiple uneven reflectors
Heavy Corrosion
Measuring on heavily corroded steel will cause the ultrasound echo
pulses to scatter and be absorbed. The ultrasound will be reflected
from multiple points as there is no one true metal thickness. This
makes it difficult for the gauge to identify the three equi-spaced
echo pulses. What you might see on the A-scan display is only one
or two echo pulses as shown below: