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Single echo measurements use a twin element (twin element)
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.
Echo-Echo Mode (EE) (Mode 3)
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 liable to give incorrect readings.
As the Cygnus 2
+
gauge does not have an A-Scan display there is
no way the user can check the measurement is correct.
Echo-echo mode must therefore be used with caution, and only on
thin paint surface coatings (less than 0.5mm). 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).
Measuring Non-Steels
The gauge will measure the following non-steels;
• Aluminium alloys
• Copper and Brass alloys
• Titanium
Use the same rules as steels when selecting a suitable probe. The
gauge will ideally be re-calibrated to suit the metal being
measured, or the standard velocity of sound for that material
would be entered into the gauge.
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