DeFelsko PosiTector UTG Guide D'utilisation page 3

Probes
When powered-up the PosiTector automatically determines
what type of probe is attached and does a self-check.
To disconnect a probe from a body, slide the plastic probe
connector horizontally (in the direction of the arrow) away
from the body. Reverse these steps to attach a new probe.
It is not necessary to power-down the Gage when
switching probes.
The PosiTector gage body accepts a wide variety of probe
types including magnetic, eddy-current and ultrasonic coating
thickness, surface profile, environmental, shore hardness and
ultrasonic wall thickness probes. See www.defelsko.com/probes
PosiTector UTG probes transmit an ultrasonic pulse into the
material to be measured. This pulse travels through the material
towards the other side. When it encounters an interface such as air
(back wall) or another material, the pulse is reflected back to the
probe. The time required for the pulse to propogate through the
t t
material is measured by the Gage, represented as and below.
1 2
PosiTector UTGC and UTGM (in single-echo
mode) probes
t t
determine thickness by measuring (uncoated) or (coated),
1 2
dividing it by two and then multiplying by the velocity of sound
for that material (steel). See Figure 1.
t
Probe
2
t
Probe
1
Figure 1
t t
>
2 1
t
For uncoated materials relates directly to material thickness.
1
When a material is coated the propagation time is increased and
t
is shown above as .
2
Coatings such as paint have a slower velocity of sound than that
of metal. Thus the single-echo technique will produce a thickness
+
result greater than the actual combined coating metal thickness.
2