GE DMS Go+, Operating Manual

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Wall thickness measurement using the DMS Go+ 1 Introduction
DMS Go+ Edition 4 (05/2014) 1-15
1.5 Wall thickness measurement
using the DMS Go+
Principle of ultrasonic measurement
At first, the DMS Go+ generates an electric initial pulse
which is guided to the transmitter element of the probe.
Once there, it is converted into a mechanical ultrasonic
pulse. By means of a couplant, the ultrasonic pulse is
transmitted from the probe to the material to be tested
which it passes through at a velocity typical of the mate-
rial (sound velocity of the material) until it encounters a
change in the material. Part of the pulse energy is re-
flected from there and sent back to the probe (echo). If
the signal reaches the backwall of the test object before
that, the reflected pulse is called backwall echo.
A probe can have one (single-element probe) or several
transducer elements (dual-element probe).
Dual-element probes are especially suitable in the case
of:
● flaws reaching close to the sound entry surface, i.e.
especially in the case of
● deep-level corrosion and erosion.