Dakota Ultrasonics VX User Manual
Page 17
VX Ultrasonic Velocity Gauge
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At this point, the VX has successfully calculated it's internal error factor,
and will compensate for this value in any subsequent measurements.
When performing a "probe-zero", the VX will always use the sound-velocity
value of the built-in probe-disc, even if some other velocity value has been
entered for making actual measurements. Though the VX will remember
the last "probe-zero" performed, it is generally a good idea to perform a
"probe-zero" whenever the gauge is turned on, as well as any time a
different transducer is used. This will ensure that the instrument is always
correctly zeroed.
Calibration
In order for the VX to make accurate measurements, it must be set to
the exact thickness the material being measured. Different types of
material have different inherent sound-velocities. For example, the velocity
of sound through steel is about 0.233 inches-per-microsecond, versus that
of aluminum, which is about 0.248 inches-per-microsecond. If the gauge is
not set to the correct thickness, all of the measurements the gauge makes
will be erroneous.