Topcoat (Measurement Mode) (Optional); Specify Topcoat Probe And Measurement; Mode - GE MFE DMS 2 Operating Manual

8. Application Notes and Optional Features

8.4 TopCOAT (Measurement Mode) (Optional)

The TopCOAT thickness measurement technique enhances
the ability to measure through coatings. This technology also
provides the user with the ability to measure the thickness of
most non-coated metals and other ultrasonic measurable
materials without a same-material calibration standard.
This technique relies on a two-channel TopCOAT probe. In the
T-COAT measurement mode (for coated surfaces), one channel
measures the coating thickness while the other measures the
total thickness of the coating plus the material being tested
(Figure 8-3). The measurements are taken using the Initial-
Pulse-to-First method. This method is the most effective way to
measure material thickness when irregular backwalls (due to
pitting, erosion, corrosion, etc) are present.
With the TopCOAT technique, through-coating measurements
can now be taken with the same "high-gain" results previously
limited to non-coated materials. This means that the T-COAT
probe allows for measurement of thinner materials and delivers
the maximum sensitivity to pitting and other surface irregularities.
In this section of the manual you will learn how to
• Select TopCOAT measurement mode (8.4.1)
• Calibrate for TopCOAT measurements (8.4.2)
• Zero a TopCOAT probe (8.4.3)
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FIGURE 8-3—TopCOAT Measurement Mode
• Calibrate the instrument for specific coating's accoustical
velocity (8.4.4)
• Change the factory-input velocity-reference data (8.4.5)
8.4.1 Specifying TopCOAT Probe and Measurement

Mode

Step 1: Connect the TopCOAT probe-cable connector to the
keyed ports on the top of the DMS 2.
DMS 2 Operating Manual