M5-CYG4P-M-01_Iss5.doc
Cygnus 4+ Operating Manual
17
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. See section Using the A-Scan Display on page 33.
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.
But as the Cygnus 4
+
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 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