ACS A1270 EMAT, Руководство по эксплуатации

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А1270 Electro-Magnetic Ultrasonic Thickness Gauge
Operation Manual
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ACOUSTIC
CONTROL
SYSTEMS
2.4 PERFORMING MEASUREMENTS
Prior to thickness measurement select a transducer from the library, adjust the instrument and chose the material for measure-
ment. If the set propagation velocity in the material differs from the actual value, adjust the velocity manually or perform the calibration.
The accuracy of the settings influences the measurement accuracy directly. You can use the library of materials if the evaluation
measurements are allowed.
If accurate results are required, then take the sample made of the same material as the inspected object, and adjust the velocity
using this sample. You have to adjust the velocity with the EMAT you will use for measurements. A plane parallel sample with smooth
surfaces will be the best. Note that the highest thickness value of the sample (within the available range) and the best quality of its
surface possible allow the best adjustment of the instrument to the ultrasonic velocity in it.
The place where the transducer is installed shall be clean, without local defects hindering the installation of the transducer on the
surface. It is not possible to receive measurement results from a cavity if the transducer cannot be placed on its bottom.
The EMAT shall be installed perpendicular to the plane of the inspected object. Don't force the EMAT against the surface.
When the EMAT touches the surface of the inspected object a reliable ultrasonic contact of the transducer with the object is reached
in a fraction of a second as a rule. Now, readings are displaed on the screen of the instrument. The readings can slightly deviate when
inspecting small-diameter pipes and if the transducer is shaking a little. The redings remain stable when inspecting flat objects.
Wait for 1-2 seconds after the readings are indicated to evaluate their stability. Afterwards leave the transducer on the surface of
the object being inspected and read the measurement results on the screen or record them in the memory.
2.4.1 Functional check of the instrument during inspection
You may need to perform a functional check of the instrument during inspection if, e.g., you have a series of low-quality readings
during the measurement.
The calibration sample built-in into the instrument is used to perform the functionality check. Its thickness is 5 mm, the ultrasonic
propagation velocity in it is 3120 m/s.
Set the velocity value in the instrument to 3120 m/s and place the EMAT on the sample. If the instrument operates properly, the
measured thickness value will be 5 mm taking into account the measurement uncertainty.
In the "MS Excel" program
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