The PosiTector 200 Ultrasonic Coating Thickness Gage for measuring coating thickness on non-metals such as wood, plastic, and concrete is the result of six generations of product innovation, and for many applications it remains the only economical, non-destructive coating thickness measurement option on the market.
The time-tested and proven non-destructive ultrasonic technique conforms to ASTM D6132, ISO 2808, and SSPC PA-17 and is widely accepted by many international organizations.
In the past, measuring coating thickness on non-metals such as wood, plastic, and concrete required destructive cross-sectioning methods. Everything changed in the early 90’s with the introduction of the PosiTector 100, the first hand-held ultrasonic coating thickness gage. For the first time, it was possible to measure coating thickness over a range of non-metal substrates using a novel method- ultrasound.
With ultrasound, an ultrasonic pulse is sent through the coating. The pulse reflects from any change in density, such as the interface between the coating and substrate or between coating layers. These reflections are analyzed to determine the coating thickness.
PosiTector 200 probes connect to the award-winning PosiTector platform, allowing a single gage body to transform to a coating thickness gage, dew point meter, surface profile gage, soluble salt tester, hardness tester, gloss meter, or ultrasonic wall thickness gage.
The PosiTector gage body is available in either Standard or Advanced models. All models feature a large touchscreen display, easy-to-navigate menus, internal memory, an IP65-rated enclosure, and the new Max Thick mode. Advanced models feature additional memory, Wi-Fi and Bluetooth connectivity, onscreen graphing, and more.
Both models can measure the total thickness of a coating system, but PosiTector Advanced gage bodies can measure up to three individual layer thicknesses in a multi-layer system.
The PosiTector gage body is available in either Standard or Advanced models. Visit defelsko.com/positector to learn more, or watch the PosiTector video linked below.
Three probes are available to measure a range of different substrates and expected coating thicknesses:
The PosiTector 200 B probe is ideal for measuring thin polymer coatings on wood and plastics up to one thousand microns or 40 mils thick
The C probe is ideal for measuring thick polymer coatings on concrete and gelcoat on fiberglass up to 38 hundred microns or 150 mils thick.
The D probe was specifically designed to measure very thick, soft coatings like polyurea, asphaltic neoprene, and thick polymers up to 76 hundred microns or 300 mils. With ‘Polyurea mode’ selected, the gage loads a pre-programmed mode optimized for polyurea measurement.
Measuring with any PosiTector 200 probe is simple. Most standards describe the following four operational steps: calibrate, verify, adjust, and measure.
Calibration is performed by DeFelsko or an accredited laboratory, and involves taking measurements on traceable standards throughout the range of the probe under controlled conditions. The result is a long-form certificate of calibration, which is included at no charge with every PosiTector 200.
Verification is typically performed at the beginning of a work shift, if the instrument has been dropped, or if erroneous readings are suspected. It ensures that the PosiTector 200 is measuring accurately at the time of use.
Power the gage on with the center navigation button. Hold the instrument near the probe by the outer shell—not the cable.
For all measurements, couplant is required to help propagate ultrasound into the coating. The included gel is ideal for rough coatings and for vertical surfaces; alternatively, a drop of water is often sufficient for smooth coatings on horizontal surfaces. Only a small, pea-sized drop is necessary.
Simply take measurements on plastic shims, test blocks, or certified coating thickness standards and ensure that the instrument is measuring within the combined tolerance of both the standard and instrument.
For most applications, the only adjustment required for PosiTector 200 probes is to zero the probe to compensate for temperature and any probe wear.
To ZERO the probe, first allow it to reach ambient temperature, then select Zero from the Cal Settings Menu. Ensure the probe is clean of couplant and hold the probe in the air, away from any surfaces. Select OK to complete the zero process. Unlike magnetic or eddy-current coating thickness probes, there is no need to measure zero on the uncoated substrate.
Since ultrasound travels at the same speed through most coatings, the PosiTector 200 measures most applications accurately with no further adjustment required. To determine if an adjustment is necessary, measure a sample of known thickness. If the average of a series of readings is not close to the known thickness, a Thickness adjustment should be made.
To adjust to a known thickness, open the “Cal Settings” menu and select the “Thickness” menu option. Take a measurement on the sample, and use the “Plus” or “Minus” buttons to increase or decrease the displayed measurement value to match it’s known thickness. To save adjustments, select “OK”
For Advanced models with multiple layers selected, use the “Down” arrow button to select the subsequent layers and adjust as necessary.
The PosiTector 200 is now ready to measure. Simply place the probe onto the coated surface and press down with sufficient pressure to depress the probe housing towards the surface.
The instrument sends an ultrasonic pulse into the coating and listens for reflections from the coating-substrate or coating-coating interface, quickly displaying the thickness measurement on the display.
International organizations such as ISO, ASTM and AMPP recommend calculating the average of several readings. This is easy with the PosiTector 200: simply turn on memory to display a running average alongside the minimum and maximum values and the standard deviation.
The default measurement mode on the PosiTector 200 has been successfully utilized for decades to measure coating thickness on a wide variety of coatings and substrates. The PosiTector 200 searches for the loudest ultrasonic echo within its measurement range, and reports it as the coating thickness. In multi-layer mode, the thicknesses associated with the loudest echoes (depending on the number of layers selected) are reported as individual layer thicknesses.
Applications with surface roughness can generate loud, unwanted reflections near the surface, causing the instrument to report the distance between the probe and the valleys of the surface profile, instead of the coating thickness. There are two options to overcome this challenge:
The innovative Max Thick mode ignores these surface reflections, and instead, searches for the deepest significant reflections, usually corresponding to the total coating thickness. Simply enable Max Thick mode from the Setup menu, and begin measuring. For more information read the article linked below – Measuring Total Coating Thickness using Max Thick Mode.
If Max Thick mode is not suitable for the coating or substrate, the gage can also be set to ignore reflections outside a selected range, using the Range menu setting. To learn more, watch the video linked in the description.
When connected to an Advanced gage body, additional features are available. Up to three individual coating layers in a multi-layer system can be measured, and Graphics Mode is available for analyzing the instrument’s readings. After each measurement, a graph is displayed showing the reflected ultrasonic pulses. The left and right sides of the graph represent the low and high ends of the measurement range, respectively. The strength of each reflection is shown by the height of the peak. Graphics mode is ideal for measuring new or unknown coating systems where the expected coating thickness or number of layers is unknown- a distinct, repeatable peak indicates a reliable measurement.
In this example, a clear reflection is visible between the layers, and from the substrate. Selecting three layers from the gage menu quickly displays these individual thicknesses. The cursor can be used to measure the depth of smaller reflections, and to measure the thickness of additional layers.
Once measurements have been saved, PosiSoft Software makes it easy to manage data from multiple probes and create professional, custom reports. Simply connect the USB cable or join the same WiFi network as your computer, import your readings, and quickly save a PDF report. Learn more about PosiSoft Software in the, “How to use PosiSoft Software for Better Coating Inspection” video.
For almost 30 years, DeFelsko has been the leader in ultrasonic coating thickness measurement, manufacturing simple, durable, and accurate gages. Backed by DeFelsko’s renowned quality, customer service, and exceptional two-year warranty, the sixth generation PosiTector 200 is the ideal choice for measuring coating thickness on non-metals.