Cygnus DIVE Operating Manual
M3-DIVE-M-ENG_Iss9.docx
Page 29 of 117
However single echo mode will not ignore any surface coatings, so
if you measure through a coating it will give an incorrect metal
thickness measurement. If the surface coating is very thin (0.2mm
/ 0.01”) paint you can make an allowance for this error, but
thicker coatings introduce too much error to be practical.
Single echo measurements use a twin element (twin crystal)
probe, because there are two elements angled to a focal point
there is a v-path error introduced. However this v-path error is
mostly corrected by the gauge, and furthermore by performing a
two point calibration.
Twin element probes require “zeroing” at regular intervals,
especially if the ambient temperature is changing.
To overcome some of the drawbacks of Single Echo measurements
the gauge has an A-Scan display that can be used to visually
verify the thickness measurements are sensible and therefore
reliable.
Echo-Echo Mode (EE)
Echo-Echo mode uses a twin element probe, but measures
between the first two echoes. This method is intended to ignore
any thin surface coatings whilst still using a twin element probe.
Echo-Echo mode is not able to verify its measurements unlike
Multiple Echo mode, therefore it is possible to give incorrect
readings. But as the DIVE gauge has an A-Scan display you can
use this to visually decide if the measurement given is correct.
Echo-echo mode must therefore be used with caution, and only on
thin pain
t surface coatings (less than 0.5mm/0.02”). It is
recommended a Single Echo measurement should also be made to
help verify the measurement makes sense (the Single Echo
measurement should always be slightly thicker due to the coating
thickness).
The DIVE gauge will perform a basic verification check on any
Echo-Echo signal before it calculates thickness. If the position of