Dakota Ultrasonics Corrosion Thickness Transducers

Q: How do I choose between a 3/16", 1/4", and 1/2" diameter dual-element transducer?

3/16" (4.76 mm) Diameter ( T-101 Series): Provides the smallest contact footprint for tightly curved surfaces such as small-diameter boiler tubes, heat exchanger coils, and motorsport chassis tubing, as well as thin walls ( 0.025" to 2.0" ). 1/4" (6.35 mm) Diameter ( T-102 / T-042 Series): The most versatile general-purpose size, balancing curved-pipe contact and flat-plate stability across 0.040" to 8.00"+ ( 1.0 to 200+ mm ). 1/2" (12.7 mm) Diameter ( T-104 / T-044 Series): Delivers a wider ultrasonic beam and higher acoustic energy for thick steel plates, large storage tanks, ship hulls, and attenuative materials like cast iron or fiberglass.

Q: How does transducer frequency (1.0 MHz, 2.25 MHz, 5.0 MHz, 7.5 MHz, 10.0 MHz) affect measurement?

Higher frequencies ( 7.5 MHz and 10.0 MHz ) produce shorter wavelengths that resolve very thin walls ( down to 0.025" ) and fine pitting, or match the acoustic characteristics of cast aluminum ( T-104-4000 ). Medium frequency ( 5.0 MHz ) is the industry standard for general steel corrosion surveys. Lower frequencies ( 1.0 MHz and 2.25 MHz , such as the T-102-1000 and T-104-1000 ) offer superior penetration power through thick sections and coarse-grained materials that scatter sound waves (such as cast iron, brass, rubber, and FRP composites).

Q: What is the difference between Standard (-2000), Hi-Damped (-2700), and Coating (-2900) 5 MHz probes?

Standard ( T-102-2000 / T-104-2000 ): Designed for Pulse-Echo (P-E) measurements on uncoated substrates. Hi-Damped ( T-102-2700 / T-104-2700 / T-042-2700 ): Incorporates heavy acoustic damping ( HD ) to shorten pulse ringing, required for Echo-Echo (E-E / Thru-Paint) gauges (such as the ZX-6, ZX-6DL, TI-25MXT, MMX, and MVX ) to measure metal wall thickness through paint without removing the coating. Coating ( T-101-2900 / T-102-2900 / T-104-2900 ): Calibrated specifically for CMX / TI-CMX series gauges ( CT mode) to measure both the coating thickness and the metal wall thickness simultaneously.

Q: What duty cycle is required when using High-Temperature (650°F or 900°F) transducers?

When measuring hot surfaces between 200°F and 650°F (343°C) with T-042 / T-044 probes—or up to 900°F (500°C) with the Dakota T-212-2001 —always use a high-temperature ultrasonic couplant (such as Sono 600 or Sono 900 ) and follow an intermittent contact duty cycle (hold the probe on the hot surface for no more than 5–10 seconds per reading, then allow it to cool in the air) to protect the internal piezoelectric elements from thermal depolarization.

F.A.Q.

How do I choose between a 3/16", 1/4", and 1/2" diameter dual-element transducer?

3/16" (4.76 mm) Diameter (T-101 Series): Provides the smallest contact footprint for tightly curved surfaces such as small-diameter boiler tubes, heat exchanger coils, and motorsport chassis tubing, as well as thin walls (0.025" to 2.0").

1/4" (6.35 mm) Diameter (T-102 / T-042 Series): The most versatile general-purpose size, balancing curved-pipe contact and flat-plate stability across 0.040" to 8.00"+ (1.0 to 200+ mm).

1/2" (12.7 mm) Diameter (T-104 / T-044 Series): Delivers a wider ultrasonic beam and higher acoustic energy for thick steel plates, large storage tanks, ship hulls, and attenuative materials like cast iron or fiberglass.

How does transducer frequency (1.0 MHz, 2.25 MHz, 5.0 MHz, 7.5 MHz, 10.0 MHz) affect measurement?

Higher frequencies (7.5 MHz and 10.0 MHz) produce shorter wavelengths that resolve very thin walls (down to 0.025") and fine pitting, or match the acoustic characteristics of cast aluminum (T-104-4000). Medium frequency (5.0 MHz) is the industry standard for general steel corrosion surveys. Lower frequencies (1.0 MHz and 2.25 MHz, such as the T-102-1000 and T-104-1000) offer superior penetration power through thick sections and coarse-grained materials that scatter sound waves (such as cast iron, brass, rubber, and FRP composites).

What is the difference between Standard (-2000), Hi-Damped (-2700), and Coating (-2900) 5 MHz probes?

Standard (T-102-2000 / T-104-2000): Designed for Pulse-Echo (P-E) measurements on uncoated substrates.

Hi-Damped (T-102-2700 / T-104-2700 / T-042-2700): Incorporates heavy acoustic damping (HD) to shorten pulse ringing, required for Echo-Echo (E-E / Thru-Paint) gauges (such as the ZX-6, ZX-6DL, TI-25MXT, MMX, and MVX) to measure metal wall thickness through paint without removing the coating.

Coating (T-101-2900 / T-102-2900 / T-104-2900): Calibrated specifically for CMX / TI-CMX series gauges (CT mode) to measure both the coating thickness and the metal wall thickness simultaneously.

What duty cycle is required when using High-Temperature (650°F or 900°F) transducers?

When measuring hot surfaces between 200°F and 650°F (343°C) with T-042 / T-044 probes—or up to 900°F (500°C) with the Dakota T-212-2001—always use a high-temperature ultrasonic couplant (such as Sono 600 or Sono 900) and follow an intermittent contact duty cycle (hold the probe on the hot surface for no more than 5–10 seconds per reading, then allow it to cool in the air) to protect the internal piezoelectric elements from thermal depolarization.