Dakota Ultrasonics PX-7 User Manual

Page 18

Dakota Ultrasonics

altered by the user. Press and hold the DOWN arrow key while

powering up the PX-7 to toggle the LOC feature on/off. Repeat

procedure to toggle on/off status.

Calibration

In order for the PX-7 to make accurate measurements, it must be set to

the correct sound-velocity for 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 tool is not set to the correct sound-velocity, all of the measurements the

tool makes will be erroneous by some fixed percentage. The one point

calibration is the simplest and most commonly used calibration procedure -

optimizing linearity over large ranges. The PX-7 provides two simple

methods for setting the sound-velocity, described in the following pages.