Checkline TI-CMXDL - Manual (Page 25)

6.0 T AKING M EASUREMENTS
The steps involved in making measurements are detailed in this section. The following section
outline how to setup and prepare your TI-CMXDL for field use.
An automatic or manual zero must always be performed. The auto zero is an off block electron
zero that does not require a zero reference block. This will most always be the zero option of
choice, as it makes the zeroing process very easy and convenient to perform. However, If the
manual zero option is enabled, the probe zero must be measured on the reference disk (battery
disk) attached to the top of the instrument. The zero compensates for variations in the transduc
In all modes the sound velocity must be determined. The sound velocity is used to convert the
transit time to a physical length. The sound velocity can be selected from a material chart in th
manual, selected from a material list in the TI-CMXDL, or for greater precision determined fro
a sample of the test material that has been mechanically measured. To enter the velocity from a
table, look up the material on the chart in the appendix of this manual and refer to the section
below on Calibration to a Known Velocity. To determine the velocity of a single sample, refer
the Material Calibration section 6.0
When measuring curved materials, it is more accurate to calibrate from two test points, one at
minimum limit of the target thickness and one at the maximum limit. In this case the reference
disk mounted to the TI-CMXDL is not used. This is called two-point calibration and is describ
on section 6.0.
6.1 Auto Probe Recognition & Selecting The Transducer Type
The first step in using the TI-CMXDL is to plug the transducer into the gauge and powe
the unit up. The TI-CMXDL has a special built-in automatic probe recognition feature th
will check to see if the probe plugged into the gauge is an auto recognized probe type. I
so, the TI-CMXDL will display a message indicating the transducer type and ask the use
for confirmation to use the identified probe. If the transducer is not an auto recognized
probe, the TI-CMXDL will display a message indicating the transducer type has not bee
recognized, and force the user to select a transducer type from a list of transducers accor
ing to frequency and diameter. Whether the transducer is auto recognized or selected fro
a predefined list, the TI-CMXDL will recall specific properties about the transducer.
NOTE: Once the transducer has been selected, the TI-CMXDL will store and recall this
transducer type every time the TI-CMXDL is powered on/off. The type will only change
the user physically selects another type from the list, or selects a previously saved setup
Therefore, if you have previously gone through this section and selected the transducer y
are using, proceed to the next section. Use the following steps to select your transducer ty
NOTE: If the transducer is not identified on power up, be sure the transducer type
Selected is the same as the transducer plugged into the TI-CMXDL. Failure to do this w
result in erroneous measurements:
In this first example the transducer was automatically identified:
1. Press the OK key once to use the identified probe, or ESC
to display a list of optional transducers.
NOTE: If the TI-CMXDL recognizes a specific transducer, the
user should always select OK to use the identified probe. The
only time an alternative probe should be selected from a list
is if the user switched probes following initial power up and
recognition, or the TI-CMXDL has somehow identified the
probe in error..
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2. Apply a drop of couplant on the transducer and place the transducer in steady contact
with the thinner of the two coating and samples. Be sure that the reading is stable and
the repeatability indicator, in the top left corner of the display, is fully lit and stable.
Press the MENU key once to activate the menu items tab. Press the MENU key multiple
times to tab right and the ESC key multiple times to tab left until the CAL menu is
highlighted and displaying the submenu items.
3. Use the UP and DOWN arrow keys to scroll through the sub
menu items until COATING 2PT is highlighted.
4. Press the ENTER key to display the Digits Edit Box.
5. Press the UP and DOWN arrow keys to scroll the highlighted
value.
6. Press the LEFT and RIGHT arrow keys to scroll the digit
locations.
7. Repeat steps 5 & 6 until the known thickness value is correctly
displayed.
8. Press the OK key to calculate the velocity and return to the menu screen,
or ESC to cancel the coating one point calibration.
9. Finally, press the MEAS key to return to the measurement screen and begin taking
readings.
NOTE: CHECK YOUR CALIBRATION! Place the transducer back on both calibration
points. The coating thickness readings should now match the known thickness values of
each sample. If the thickness is not correct, repeat the steps above.
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