3.2
Condition
and
Preparation
of
Surfaces
In any ultrasonic measurement scenario, the shape and roughness of the test surface are of paramount
importance. Rough, uneven surfaces may limit the penetration of ultrasound through the material, and result in
unstable, and therefore unreliable, measurements. The surface being measured should be clean, and free of any small
particulate matter, rust, or scale. The presence of such obstructions will prevent the transducer from seating properly
against the surface. Often, a wire brush or scraper will be helpful in cleaning surfaces. In more extreme cases, rotary
sanders or grinding wheels may be used, though care must be taken to prevent surface gouging, which will inhibit
proper transducer coupling.
Extremely rough surfaces, such as the pebble‐like finish of some cast iron, will prove most difficult to measure.
These kinds of surfaces act on the sound beam like frosted glass on light, the beam becomes diffused and scattered in
all directions.
In addition to posing obstacles to measurement, rough surfaces contribute to excessive wear of the transducer,
particularly in situations where the transducer is “scrubbed” along the surface. Transducers should be inspected on a
regular basis, for signs of uneven wear of the wearface. If the wearface is worn on one side more than another, the
sound beam penetrating the test material may no longer be perpendicular to the material surface. In this case, it will
be difficult to exactly locate tiny irregularities in the material being measured, as the focus of the sound beam no
longer lies directly beneath the transducer.
4
Operation
4.1
Power
On/Off
The instrument is turned on by pressing the
key.
The gauge can be turned off by pressing the
key while it is on. The UTG‐2900 will retain all of its settings
even when the power is off.
4.2
Setting
the
Measurement
Mode
Often times users and inspectors in the field are faced with coated materials such as pipes and tanks. Typically
inspectors will need to remove the paint or coating prior to measuring, or allow for some fixed amount of error
introduced by the paint or coating thickness and velocity.
The error can be eliminated with this gauge by using a special echo‐echo mode to perform measurements for
applications such as this. The gauge gives you this feature in a simple way, one button toggle, eliminating the need to
remove the paint or coating.
To switch between
pulse
‐
echo
mode and
echo
‐
echo
mode, simply press the
key.
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