Standard Gauge - Dakota CX2
Ultrasonic thickness gauges come in many forms, each with different features. From the very standard, such as the Dakota CX2, to the much more advanced gauges.
This standard gauge is a simple low cost ultrasonic thickness gauge. The gauge uses one velocity - the velocity for mild steel. It cannot be calibrated for any other material. It can take four readings per second.
It is ideal for a user taking thickness measurements on mild steel only. It cannot measure other materials correctly.
In addition to the material thickness measurement, the Dakota CX2 displays key statistical values required to assess the overall material thickness, number of readings (n), the average material thickness (x̄), the lowest (Lo) and highest (Hi) material thickness, the standard deviation (σ) and the
co-efficient of variation (cv%).
Advanced Gauges - Dakota CX4, 6 & 8
The first gauge in the range to enable calibration on any material is the Dakota CX4, this gauge can be calibrated using a one point calibration. The speed of sound can be entered for any material or a value can be chosen from a list of materials. Two point calibration is an additional option in the Dakota CX6 and CX8 gauges.
The Dakota CX4 gauge takes 4 readings per second whereas the MTG6 and MTG8 gauges can take 4, 8 or 16 readings per second whilst displaying the thickness value.
The Dakota CX6 and CX8 also have a high speed scan feature which takes 16 readings per second. This allows the user to “scrub” the probe over the surface, continuously displaying the thickness. When the probe is removed from the surface, the thinnest thickness measured is displayed, showing the most potential point for failure.
The Dakota CX6 and CX8 can display a run chart as one of the display options, along with statistics and the Dakota CX8 can also display a B-scan.
Differential mode and limits are two of the features available on the Dakota CX8.
In differential mode, a “target” thickness can be entered into the gauge and when measuring, the gauge will display the variance from that value.
For example, if a target thickness of 20 is entered into the gauge and a thickness of 25 is measured, the gauge will display a reading of “+5”. If a thickness of 17 is measured, a reading of “-3” will be displayed.
The limit mode allows a value to be entered into the gauge. If a reading is taken below this value, the alarm will sound and the red LED on the keyboard will light.
The Dakota CX6 and CX8 gauges also have data logging capabilities. The CX6 gauge can log 1,500 readings sequentially, i.e. as a list, and the MTG8 can log up to 100,000. Data logging is the ultrasonic term for the function known as batching in dry film thickness.
The Dakota CX 4, 6 and 8 models can use the Echo – Echo (E-E) method meaning they have ThruPaintTM capability. Enabling the user, when using a ThruPaintTM probe, to obtain the thickness of the substrate only, ignoring the coating thickness.