Dakota Ultrasonics PX-7 DL - Manual (Page 17)

PX-7 DL Ultrasonic Thickness Gauge
13
Calibration
In order for the PX-7 DL 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 DL provides two simple
methods for setting the sound-velocity, described in the following pages.