DeFelsko PosiTector UTG User Manual
PosiTector UTG
INSTRUCTION MANUAL v. 2.2
for UTG ME models
Simple. Durable. Accurate.
Ultrasonic Thickness Gage
Introduction
Introduction
2
The PosiTector UTG ME is a hand-held Ultrasonic
Thickness Gage that uses the non-destructive ultrasonic pulse-echo principle to measure the wall thickness of a wide variety of materials. The default and
most common setting for the PosiTector UTG is
multiple-echo (ME) mode. In ME mode the Gage
measures the metal thickness of a painted structure,
disregarding the paint thickness. The user can
switch the gage to single-echo mode by selecting SE
Mode from the Gage menu (see pg.15).
The probe (a single element contact transducer)
transmits 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 echoed back to the probe. The time required
for the pulse to propogate through the material is
measured by the Gage, represented as t
1
and t
2
below.
In single-echo mode (see Figure 1) the Gage
determines thickness by measuring t1(uncoated) or
t2 (coated), dividing it by two and then multiplying by
the velocity of sound for that material (steel).
steel
coating
steel
2
t
>
1
t
For uncoated materials t1relates directly to material
thickness. When a material is coated the propaga-
tion time is increased and is shown above as t
2
.
Coatings such as paint have a slower velocity of
Figure 1
2
t
1
t
Probe
Probe
3
In multiple-echo mode the Gage determines
thickness by measuring the time between at least
three consecutive back wall echoes.
steel
In the figure above, multiple-echo mode measures
only the time between echoes. Regardless of
whether the steel is coated or not, all times between
echoes are the same. In multiple-echo mode
the Gage determines thickness by measuring
t
1+t2+t3
, dividing it by six and then multiplying by the
velocity of sound for that material. The resultant
thickness calculation made by the instrument is
therefore an accurate measurement of the steel
thickness only, disregarding the coating thickness.
The velocity of sound is expressed in inches per
microsecond or meters per second. It is different for
all materials. For example, sound travels through
steel faster (~0.233 in/µs) than it travels through
plastic (~0.086 in/µs).
Probe
1
t
2
t
3
t
1
t
2
t
3
t
Coating
Figure 2
Operation Overview
Operation Overview
1. Turn the Gage ON (see Power-Up - pg. 5)
2. Verify accuracy (see Verification - pg. 9)
3. Select the correct velocity of sound (see pg. 10)
4. Measure the part (see How to Measure - pg. 5)
Probe
sound than that of metal. Thus the single-echo technique will produce a thickness result greater than the
actual combined coating+metal thickness.
4
Zero
Plate
Finger
Grip
Wear Face
(Measurement Head)
USB/IR Port
Probe
connector
Bi-color
indicator
light
Display
Probe
(transducer)
Typical Display
Current
Measurement
Currently
selected
material
Unit of
Measurement
The Coupled
Symbol appears
when the probe
is ultrasonically
connected with a
surface.
inch
Steel
Battery
Icon
Measurement Mode Currently set to ME
5
How to Measure
How to Measure
1. Remove black rubber cap from probe
if supplied. Couplant (glycol gel included) must be applied to the surface
to be tested to eliminate air gaps
between the wear face and the surface. A single
drop of couplant is sufficient when taking a spot
measurement.
2. Place the probe flat on the surface. Use moderate pressure to press against the top of the probe
with the thumb or index finger. When the probe senses echoed ultrasound, a coupled symbol will
appear on the display and thickness values will be
displayed. While the probe is coupled, the
PosiTector UTG will perform 3 readings per second,
updating the display each time.
3. When the probe is removed from the surface, the
last measurement will remain on the display.
Occasionally, excess couplant will remain on the
probe when the probe is lifted from the surface. This
may cause the PosiTector UTG to display a final
measurement value different from those observed
when the probe was on the surface. Discard this
value and repeat the measurement.
Power-up / Power-down
Power-up / Power-down
The PosiTector UTG powers-up when any button is
pressed. To preserve battery life, the Gage powersdown after approximately 3 minutes of no activity. All
settings are retained.
Throughout this manual, the symbol
indicates more information about the particular topic
or feature is available on our website.
Go to: www.defelsko.com/manuals
NOTE:
6
Surface Conditions
Surface Conditions
Ultrasonic measurements are affected by the
condition, roughness and contour of the surface to
be tested.
Measurement results may vary on coarse surfaces.
Where possible, it is recommended to seat the
transducer on a smooth flat surface that is parallel to
the opposite side of the material.
On rough surfaces, the use of a generous amount of
couplant minimizes the surface effects and serves to
protect the transducer from wear, particularly when
dragging the probe across a surface.
On smooth, uncoated metal
surfaces the Gage (in ME mode) may occasionally
be unable to give a measurement result even when
the "coupled" symbol appears. Use additional
couplant and lighter pressure on the probe when
measuring. Alternatively, laying a plastic shim on the
surface with couplant applied to both sides to
simulate a painted surface will help produce a steelonly thickness measurement (multiple-echo mode).
Switching the Gage to SE mode (see pg.15) will also
help produce a steel-only thickness measurement.
Zero Menu Option
Zero Menu Option
The PosiTector UTG probe can be "zeroed" to com-
pensate for temperature and wear. This action is not
required when operating in ME (multiple-echo) mode
except when the Gage is new and after a Reset (pg.
16). However it ensures best accuracy when operating in SE (single-echo) mode. Therefore it is a good
idea to "zero" the probe before each work shift and
when the temperature of the part changes. During
zeroing, it does not matter what the current velocity
setting is.
Zero
ME Mode Note:
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