Dakota Ultrasonics PX-7 DL - Manual (Page 32)

Dakota Ultrasonics
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TRANSDUCER SELECTION
The PX-7 is inherently capable of performing measurements on a wide
range of materials, from various metals to glass and plastics. Different
types of material, however, will require the use of different transducers.
Choosing the correct transducer for a job is critical to being able to easily
perform accurate and reliable measurements. The following paragraphs
highlight the important properties of transducers, which should be
considered when selecting a transducer for a specific job.
Generally speaking, the best transducer for a job is one that sends
sufficient ultrasonic energy into the material being measured such that a
strong, stable echo is received by the PX-7. Several factors affect the
strength of ultrasound as it travels. These are outlined below:
•
Initial Signal Strength
The stronger a signal is to begin with, the stronger its return echo
will be. Initial signal strength is largely a factor of the size of the
ultrasound emitter in the transducer. A large emitting area will send
more energy into the material being measured than a small emitting
area. Thus, a so-called "1/4-inch" transducer will emit a stronger signal
than a "1/8-inch" transducer.
•
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