1. Couplant 3. Testing Material
1. Couplant 2. Coating 3. Test Material
The following gauges have both Pulse-Echo (P-E) and Echo-Echo (E-E) Modes.
Pulse-Echo (P-E) Mode measures from the surface to the back-wall echo. It is used on bare material to determine wall loss on corroded, eroded and pitted materials. When measuring through a coating the measurement will include an error due to the coating thickness x 2-3 because of the difference in sound velocity between the coating and test material.
A-Scan showing P-E measurement
Echo-Echo (E-E) Mode measures from the back-wall echo to its multiple-echo and eliminates the error due to the coating. Measurements can only be made on materials that have parallel surfaces as the multiple-echo will disappear if the back-wall is corroded or pitted.
A-Scan showing E-E measurement
A-Scan shows the signal that is being measured.
Strong Back Wall Echo and Multiple Echo
B-Scan graphs a series of measurements. This results in a profile view that is helpful to understand if the material has a single or series of pits, general corrosion, inclusion or lamination.
Consistent Back Wall Echo
The CMX Series' digital display is simple, direct reading, and can add min/max.
Digital Display with Min & Max
| A-Scan | B-Scan | ||
| Pitted material will show a signal coming before the Back-Wall Echo and a diminished or non-existent the Back Wall Echo, depth measurement will be inconsistent and vary point to point |  |
B-Scan showing various irregular thicknesses |  |
| An inclusion will show a signal coming before the Back Wall Echo but the Back Wall is unaffected. |  |
B-Scan shows inclusions at consistent depth (plateau) |  |
| A lamination usually at mid-wall and of consistent depth |  |
B-Scan showing a plateau of considerable length |  |
