Checkline TI-25DL - Manual (Page 17)

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6.2 Changing Calibration - Acoustic Velocity Is Known
To change the calibration for a material where the acoustic velocity is
known from either prior knowledge or from the Acoustic Velocity
table, proceed as follows:
1. After connecting the probe, turn on the gauge by pressing the
key.
2. Press the key.
3. If the units of measure indicators “IN” or “MM” are flashing press
the key again.
4. The acoustic velocity units indicator “IN/µs” or “M/s” should be
flashing showing that the Acoustic Velocity Calibration mode is
enabled.
5. Use the and keys to adjust the displayed value to
match the desired acoustic velocity setting. By pressing and holding
the key, the numbers will change more rapidly.
6. When the desired value is reached press the key to exit the
calibration mode and return to measurement mode.
Note: If the key is pressed while in the calibration mode, the
TI-25DL will be reset to the factory default calibration for common
steel (0.2330 IN/µs or 5920 M/s).
For Highest Accuracy
To achieve the most accurate measurements possible, it is gener-
ally advisable to calibrate the TI-25DL to a sample of “known
thickness” since material composition (and its sound velocity)
sometimes varies from lot to lot and from manufacturer to man-
ufacturer. Calibrating to a sample of known thickness will ensure
that the gauge is set as closely as possible to the sound velocity
of the material to be measured.
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7.0 DESCRIPTION OF MEASURING MODES
The TI-25DL can be used in either the Single Thickness Reading mode,
Scan
mode or Differential mode.
The Single Thickness Reading mode is suitable for most applications. While
the probe remains in contact with the material being measured, the TI-25DL
performs four (4) measurements every second, updating the LCD display
after each reading. When the probe is removed from the surface, the last
reading is retained on the display.
The Scan mode is used to survey or examine larger sections of material.
When set for Scan mode, the TI-25DL performs sixteen (16) measurements
every second, but does not display each reading. This mode is designed for
those applications where the probe will be “dragged” or lightly “scrubbed”
over the measuring surface. While the probe maintains contact with the
material being measured, the TI-25DL is keeping track of the lowest
(thinnest) measurement it encounters. Any brief interruptions in the signal
will be ignored. When the probe is removed from the surface for more than
one second, the TI-25DL will display the thinnest reading encountered dur-
ing the measurement survey. The Scan mode can be used in conjunction
with the Alarm and Beeper modes. While the probe is being scrubbed
(dragged) along the measuring surface, the audible and visual alarms will
immediately activate if the gauge encounters any readings during the scan
that are below the user set nominal value. Refer to Alarm and Beeper
Modes
, Section 8.0 for addtional details.
When set for Differential mode, the end user enters a nominal (target) thick-
ness value. The TI-25DL will then display the difference (+ or –) between
the actual measured value and the user-set nominal (target) value.
The Single Thickness Reading mode is the factory default setting. The
followings steps outline how to set the TI-25DL for the Scan or Differential
modes.
Setup For Scan mode:
1. Turn on the TI-25DL power by pressing the key
2. Press the key to activate the features and settings menu.