Checkline TI-25LT - Manual (Page 5)

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3.4 Keypad
The TI-25LT is supplied with a membrane keypad
mounted on the front of the instrument body.
It consists of three keys which are described below.
The PROBE ZERO key is used to “zero” the
probe in a similar way as a micrometer is “zeroed”
before use. If the tool is not zeroed correctly, the
measurements will not be accurate.
The INCH/MM key is used to change the measuring
units from inches to mm. Each time the key is
pressed the units will change from one to the other.
The ON/OFF key is used to turn the power on as
well as turning the power off. If the Tl-25LT is idle
for five minutes the gauge will automatically power
off.
3.5 LCD Display
The backlit LCD Display provides the operator with important information
as detailed below. .
• Measurement values
• Units of measure
• Bar graph signal stability indicator
The numeric portion of the display consists of
4-digits and is used to display numeric values,
as well as occasional simple words, to indicate
the status of various settings. When the TI-25LT
is displaying thickness measurements, the display will retain the last mea-
sured value, until a new measurement is performed.
Mode l T I-25LT
ON / OFF
PROBE ZERO
INCH / M M
PROBE ZERO
INCH / M M
ON / OFF
1.8.8.8.8
+ IN MM/ µ s
1.8.8.8.8
+ IN MM/ µ s
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6.2 Measurements Of Pipes Or Cylindrical Parts
When using the TI-25LT to measure the
wall thickness of a pipe, the orientation
of the probe is very important to obtain
accurate readings.
Pipe diameter is greater than
4 inches (100 mm):
Position the probe so the centerline of
the probe wearface is perpendicular to
the long axis of the pipe as shown in
illustration “A.”
Pipe diameter is less than
4 inches (100 mm):
Two measurements should be performed at the same location, one with the
centerline of the probe perpendicular to the long axis and one parallel
(illustration “B”).
The smaller (thinner) of the two measurements should be used as the
actual wall thickness at the measurement location.
6.3 Measurements On Materials At High Temperatures
When it is necessary to measure wall thickness on surfaces that are in
excess of 200 °F (100 °C), special-purpose high temperature probes should
be used. These probes are built using special materials and techniques that
allow them to withstand high temperatures without damage. Additionally,
care must be taken when performing a “Probe Zero” or “Calibration To
Known Thickness” using a High Temperature probe.
At such elevated temperatures, it is recommended that the user follow these
procedures:
1. Perform a calibration procedure on a sample of known thickness
(refer to section 6.3) with the material temperature at or near the
temperature that will be encountered during measurement.
Additionally, on applications on pipe diameters less than 3 inches,
we recommend using the optional V-Block fixture which helps
maintain stable probe placement on the rounded measuring surface.
A Perpendicular
B Parallel