Checkline TI-25LTX, Руководство по эксплуатации, Страница: 13 / 22

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5.0 MAKING MEASUREMENTS
The steps involved in making measurements are detailed in this section. The following
sections outline how to setup and prepare your TI-25LTX for field use.
A manual zero must always be performed. A manual probe zero is performed using the
reference disk (battery disk) attached to the top of the instrument. The zero compensates
for variations of the transducer. Once the probe zero is completed, the sound velocity
must be determined to convert the transit time to a physical length. The sound velocity
can be selected from the material chart in the manual, or manually adjusted using a
single, or multiple, known reference point(s) until the TI-25LTX correctly measuring
the reference point(s). The later will result in greater precision overall. To enter a
common velocity from a table of velocities, look up the material on the chart in
the appendix of this manual. Refer to the section below on Material Calibration for
instructions on manually adjusting the velocity using a reference point(s)/standard(s).
5.1 Probe zero
Setting the zero point of the TI-25LTX is important for the same reason that setting the
zero on a mechanical micrometer is important. It must be done prior to calibration, and
should be done throughout the day to account for any temperature changes in the probe.
If the TI-25LTX is not zeroed correctly, all the measurements taken may be in error by
some fixed value.
The “on block” zero procedure is outlined below:
1. Apply a drop of couplant on the transducer and place the transducer in steady
contact with the disk (battery cover) located at the top of the unit to obtain a
measurement.
2. Be sure all six repeatability/stability bars in the top left corner of the display are
fully illuminated and stable, and last digit of the measurement is toggling
only +/- .001
"
(.01mm).
3. Press the key to perform the manual zero. “PRB0” will briefly be displayed
on the screen, indicating the zero calculation is being performed.