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Ultrasonic Bolt Tension Meter

Ultrasonic Bolt Tension Meter Mini-Max by Dakota Ultrasonics

Ultrasonic bolt tension meter by Dakota Ultrasonics model  MINI-MAX Ultrasonic Bolt Tension Monitor, is a state of the art instrument designed to measure elongation produced by tightening a threaded fastener. The MINI-MAX can accurately measure the elongation of fasteners of virtually any material from 1/2 inch to 10 feet in length. The measurement is achieved by determining the change in the transit time of an ultrasonic shock wave along the length of the fastener as the fastener is tightened. The on-board microcomputer automatically interprets this time measurement to display the time (nanoseconds), elongation, load, stress, or %strain from stretching a fastener.

Dakota Ultrasonics Mini-Max Bolt Tension Monitoring | Advantage NDT Supplies

Measurement is achieved by determining the change in the transit time of an ultrasonic wave along the length of the fastener as the fastener is tightened using a mechanical method. The time is then converted to  elongation, load, stress, or % strain. 

The Dakota Ultrasonics Mini-Max has 4GB SD storage capacity for data storage in a group file format, as well as .tif file screen captures for additional documentation. 

DakView PC & OSX utility software completes the reporting process and allows for present and future verification.


  • Can measure bolts from 1/2″ up to 50 ft. (15.24 m).
  • Auto calibration for system zero.
  • Built in load calibration toolkit.
  • Wide range of material types and calibrations.
  • Selectable 200 volt square wave pulser (100, 150, 200 volts).
  • Variable transducer damping (50, 75, 100, 300, 600 & 1500 ohms), for use with 1-10 MHz transducers.
  • Large 110 dB gain range.
  • Variable digitizer for improved resolution and stability.
  • Temperature compensated.
  • Hi/Lo alarm limit used for for tolerances.
  • Measurement quanities – Time (nanoseconds), Elongation, Load, Stress, and Percent Strain.
  • Display Options – RF, Rectified, Large Digits with Limits Bar.
  • Display Resolution – 1/8″ VGA 240 x 160 pixels.
  • The Auto Set feature automatically optimizes detection and adjusts display.

Ultrasonic Bolt Tension Meter by Dakota Ultrasonics MAX II

Ultrasonic bolt tension meter by Dakota Ultrasonics MAX II Ultrasonic Bolt Tension Monitor is the latest gauge addition to our bolting products. It incorporates all of the Mini Max unit’s great features, with some added benefits in terms of features, hardware, speed, and length. MAX II very accurately measures fasteners up to 100 feet in length and sports our very best effort to date…in terms of overall performance and power!


  • Quantities – Elongation, Load, Stress, %Strain and Time (nanoseconds).
  • Sunlight readable color QVGA display (320×240 pixels).
  • Measure Modes – Pulse-Echo, Echo-Echo, Echo-Echo-Verify (triple echo).
  • Auto Correlation – optimize transducer placement.
  • Custom auto calibration feature.
  • 4GB internal SD & up to 64GB external SD slot memory.
  • USB 1.1 connectivity.
  • Analog, serial & alarm outputs.
  • PC interface reporting software.
  • Import & export files – between Max II and MiniMax.
  • Li-Ion pack & 6 AA
  • emergency battery backup option.
  • 2 year warranty.