Checkline TI-25SX, Operating Manual, Page: 3 / 22

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1.0 INTRODUCTION
The Checkline model TI-25SX is a basic dual element thickness gauge with the ability
to locate blind surface pitting and internal defects/flaws in materials. Based on the same
operating principles as SONAR, the TI-25SX is capable of measuring the thickness
of various materials with accuracy as high as ± 0.001 inches, or ± 0.01 millimeters.
The principle advantage of ultrasonic measurement over traditional methods is that
ultrasonic measurements can be performed with access to only one side of the material
being measured.
1.1 Disclaimer
Inherent in ultrasonic thickness measurement is the possibility that the instrument will
use the second rather than the first echo from the back surface of the material being
measured. This may result in a thickness reading that is TWICE what it should be.
Responsibility for proper use of the instrument and recognition of this phenomenon rest
solely with the user of the instrument. Other errors may occur from measuring coated
materials where the coating is insufficiently bonded to the material surface. Irregular
and inaccurate readings may result. Again, the user is responsible for proper use and
interpretation of the measurements acquired.