Tritex Multigauge 5700 Datalogger Ultrasonic Thickness Gauge www.tritexndt.com
Page 50
9.1.
How Multiple Echo Works
All Ultrasonic Thickness Gauges should be calibrated to the velocity of sound
of the material being measured. Coatings have a different velocity of sound
than metal and it is important they are not included in the measurement.
Multiple echo ensures all coatings are completely eliminated from the
measurement.
How it works:
A transmitted ultrasound pulse travels though both the coating and the metal
and reflects from the back wall. The returned echo then reverberates within the
metal, with only a small portion of the echo travelling back through the coating
each time. The timing between the small echoes gives us the timing of the
echoes within the metal, which relate to the metal thickness. The returned
echoes need not be consecutive as the gauge will interpret them automatically
and calculate the thickness. A minimum of three echoes is checked each time.
This is referred to as the
Automatic Measurement Verification System
(AMVS)
.
T
im
in
g
1
T
im
in
g
3
T
im
in
g
2
Probe
Coating
Metal
9. Using the Multigauge 5700
