Ultrasonic Thickness Gauges
F.A.Q.
How do I decide between a Corrosion Thickness Gauge and a Precision Thickness Gauge?
- Select an Ultrasonic Corrosion Thickness Gauge if your primary goal is detecting internal rust, pitting, scale, or wall thinning in pipes, tanks, boiler tubes, or structural steel (
0.025" to 36.0"range,0.001"/0.01 mmresolution). Dual-element probes excel at reflecting sound off rough, uneven interior surfaces. - Select an Ultrasonic Precision Thickness Gauge if you are measuring smooth, manufactured components—such as thin sheet metal (
down to 0.006"), plastic bottles and medical tubing (down to 0.005"), machined aerospace parts, or glass—where you require0.0001"(0.001 mm/ 1 µm) resolution.
Can an ultrasonic thickness gauge measure through paint and protective coatings without removing them?
Yes. Models equipped with Echo-Echo (E-E / Thru-Paint) mode—such as the Checkline TI-25MXT, Dakota ZX-6, Dakota ZX-6DL, and ElektroPhysik MiniTest 440—measure the transit time between two consecutive back-wall echoes inside the steel substrate, automatically ignoring external paint or epoxy coatings up to 0.040"–0.075" thick. Furthermore, combination models like the Checkline TI-CMX and Dakota CMX1-DL / CMX2-DL can display both the coating thickness and the metal wall thickness simultaneously on screen.
Why is ultrasonic couplant gel required for measurement?
High-frequency ultrasonic sound waves (1 MHz to 20 MHz) are rapidly attenuated by air—even a microscopic air gap between the transducer wear face and the test surface will block sound transmission. Applying a drop of ultrasonic couplant gel (or glycerin/high-temperature couplant for hot pipes) displaces the air barrier and allows acoustic energy to couple cleanly into the test specimen.
How do I calibrate an ultrasonic thickness gauge for different materials?
Because every material transmits sound at a distinct acoustic velocity (e.g., 0.2330 in/µs in carbon steel vs. 0.2510 in/µs in aluminum), ultrasonic gauges are calibrated in one of three ways:
- Built-In Material Presets / Direct Velocity Entry: Select the material from the onboard library or dial in its published sound velocity.
- 1-Point Calibration (Velocity Mode): Place the probe on an uncoated sample of the exact material with a known thickness and adjust the velocity until the display matches the known thickness.
- 2-Point Calibration: Calibrate across both a thin and a thick reference step on a NIST-Traceable Step Calibration Block to simultaneously set zero offset and sound velocity across your entire working range.
Dakota Ultrasonics PX-7 Precision Ultrasonic Wall Thickness Gauge
Discontinued Product
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- Dakota PX-7 High Resolution Ultrasonic Thickness gauge
Resolution: .001" (0.01 mm)
Datalogging: NO
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Dakota Ultrasonics PX-7DL Data Logging Precision Ultrasonic Wall Thickness Gauge
Discontinued Product
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- Dakota PX-7DL High Resolution Ultrasonic Thickness gauge with Data Logging
Resolution: .0001" (0.001 mm)
Datalogging: YES
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Checkline TI-45NHD Ultrasonic Wall Thickness Gauge
Discontinued Product
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- General Purpose Wall Thickness Gauge for measuring on a variety of materials with protective rubber shell
- Range:
0.040 - 8.00 inches
1.00 - 200.00 mm
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Dakota Ultrasonics VX Ultrasonic Velocity Gauge
Checkline TI-UMX2 Underwater Ultrasonic Thickness Gauge
Discontinued Product
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- Checkline TI-UMX2 Underwater Ultrasonic Thickness Gauge with datalogging
- Resolution: .001" (0.01 mm)
- Rated for dive depths up to 1000 ft (300 meters)
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