Dakota Ultrasonics MX-5 DL - Manual (Page 35)

MX-5 DL Ultrasonic Thickness Gauge
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more energy into the material being measured than a small emitting
area. Thus, a so-called "1/2-inch" transducer will emit a stronger signal
than a "1/4-inch" transducer.
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Absorption and Scattering
As ultrasound travels through any material, it is partly absorbed. If
the material through which the sound travels has any grain structure,
the sound waves will experience scattering. Both of these effects
reduce the strength of the waves, and thus, the M X-5 DL's ability to
detect the returning echo.
Higher frequency ultrasound is absorbed and scattered more than
ultrasound of a lower frequency. While it may seem that using a lower
frequency transducer might be better in every instance, low frequencies
are less directional than high frequencies. Thus, a higher frequency
transducer would be a better choice for detecting the exact location of
small pits or flaws in the material being measured.
•
Geometry of the Transducer
The physical constraints of the measuring environment sometimes
determine a transducer's suitability for a given job. Some transducers
may simply be too large to be used in tightly confined areas. Also, the
surface area available for contacting with the transducer may be limited,
requiring the use of a transducer with a small wearface. Measuring on
a curved surface, such as an engine cylinder wall, may require the use
of a transducer with a matching curved wearface.
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Temperature of the Material