DMTA-10022-01EN, Rev. C, January 2015Chapter 676Increase the gain value to make a good echo-to-echo reading. If this does not help, youcan still obtain an approximate measurement by returning to the standard echodetection mode.6.3 Measurements with Optional THRU-COAT, D7906, and D7908TransducersTHRU-COAT is an optional function that measures the true metal thickness of coatedor painted parts. This function only requires a single back-wall echo, and isrecommended for heavy corrosion applications where the outside of the material iscoated or painted. If necessary, the measurement of the coating/paint layer can also becalibrated to precisely measure the thickness of the coating/paint.In order for the THRU-COAT function to work properly, the thickness of the coatingor paint must be at least 0.125 mm (0.005 in.) thick. The maximum coating/paintthickness that THRU-COAT can measure is dependent on the type of coating, buttypically greater then 2 mm (0.080 in.).If the THRU-COAT function does not display a coating thickness, or if the coatingthickness does not seem realistic, THRU-COAT may not be able to properly resolvethe coating thickness. In such cases, the user should try a different measurementmode, like Echo-to-Echo or standard.6.3.1 Enabling the THRU-COAT FunctionThe THRU-COAT function is only available when you connect a THRU-COATtransducer (P/N: D7906 [U8450005] or D7908 [U8450008]) to the 45MG.To enable the THRU-COAT function1. Connect a THRU-COAT transducer to the 45MG.2. Turn on the instrument.3. Wipe the couplant off the transducer tip.4. Press [2nd F], [CAL ZERO] (Do ZERO) (see Figure 6-6 on page 77).
