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Dakota NDT MAX II Ultrasonic Bolt Tension Monitor

The MAX II Ultrasonic Bolt Tension Monitor is the latest gauge addition to our bolting products.  It incorporates all of the great features of the MiniMax unit, with some added benefits in terms of features, hardware, speed, and length - MAX II very accurately measures fasteners up to 100 feet in length.

The Dakota NDT Max II Bolt Tension Monitor measures the elongation very accurately in fasteners of virtually any material from 1/2 inch to 100 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 by any mechanical method.  MAX II then interprets this time measurement into a given quantity of time(nanoseconds), elongation, load, stress, or %strain while applying a load on the fastener.

 Using a variety of processing and automation, the MAX II reduces operator error. With built in data recordation and supporting DakView utility software for Windows PC & MAC OSX, the MAX II offers an easy to use and reliable solution to accommodate the most difficult bolting applications.


Dakota MAX II Specifications

Key Features:

  • 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.

Technical Speificaton

Dakota Max II Technical Spec


Power Source


  • Weight: 4.5 lbs (2.04 kgs), with batteries.

  • Size: 8.5W x 6.5H x 2.5D in (216 x 165 x 70mm).

  • Operating Temperature: 14 to 140F (-10C to 60C).

  • Keyboard: Membrane switch with 21 tactile keys.

  • Case: Extruded aluminum body with nickel plated aluminum end caps (gasket sealed).

  • Display Views: RF (full wave view), +/- Rectified (half wave view), Digits, or split screen combination (wave plus large digits).

  • Environmental: Meets IP65 requirements.

  • Lithium Ion Pack: 10.8v, 2 amp hrs, typical operation 18hrs.

  • Battery Backup: Emergency battery backup. Six 1.5V alkaline, 1.2V AA Nicad cells, 1.2V AA NI-MH, or other other equivalent power source.

  • Battery life (continuous use): Alkaline (12 hrs), Nicad (5hrs), and NI-MH (12hrs), with default settings.




  • USB: Direct USB 1.1 PC connectivity.

  • Power Connector: 12v @ 2amps, adapter 100-240 VAC, .7 Amps, 50-60 Hz.5 Pin Lemo (includes):RS232Output – RS232 PC serial interface.

  • Alarm Outputs – Two independent alarm outputs triggered by the gates.Analog Out – Proportional outputs (amplitude or distance), 0-10 volts.

  • Transducer Connectors: Two LEMO 00 connectors.

  • Log Formats: Grid (Alpha Numeric).

  • Capacity: 4 Gb internal & up to 64 Gb External SD slot.

  • Screen Capture: Tagged interface file (.tif) capture for quick documentation.

  • Custom Setups: 64 user configurations.

  • Transducer types: Single element – 1 MHz to 10 MHz frequencies, and 1/8” to 1” diameters. Magnetic & Non Magnetic options available.

  • Glue-On: Available for short bolts with minimal/short elongations to eliminate transducer placement errors.

  • Connectors: Microdot, Lemo 00, or BNC options depending on the transducer model selected.

  • Custom Transducers: Available for special applications.


  • Setups: 64 custom user defined setups; factory setups can also be edited by the user.

  • Auto Set: Automates the detection, scope, and display setting process for each individual bolt.

  • Gates: Three measurement gates, depending on measurement mode used, with adjustable start and threshold.

  • Alarm Limits: Adjustable Hi/LO tolerances with visual LED’s and audible beeper. Hardware alarm outputs (accesory cable required).

  • Field Calibration: Vector or Regression correction curve for increased accuracy using Load & Stress.

  • Display: Blanview sunlight readable QVGA TFT color display (320 x 240 pixels). Viewable area 4.54 x 3.40 in (115.2 x 86.4 mm), or 5.7 in (144.78 mm) diagonal. 16 color pallete, multiple color options and variable brightness.

  • Screen Refresh Rate: 60Hz.
    Timing: Precision TCXO timing with single shot 100 MHz 8 bit ultra low power digitizer.

  • Pulser Types: Spike, Square Wave & Tone Burst.Pulser Voltage: 100 – 400v.

  • Pulser Voltage: 100 – 400v.

  • Pulse Width: Selectable step options Spike, Thin, Wide, HV Spike, HV Thin, HV Wide, TB .5MHz, TB 1MHz, TB 2MHz, TB 5MHz, TB 10 MHz. Spike 40 ns, Square Wave 80 to 400 ns, Tone Burst 50 ns to 1 microsecond.

  • Gain: 0 to 110dB with 0.2dB resolution. Manual and AGC control.

  • Damping: 50, 75, 100, 300, 600, & 1500 ohms.

  • Frequency Band: Broadband 1.8 – 19 MHz (-3dB) filter.

  • Horizontal Linearity: +/- 0.4% FSW.

  • Vertical Linearity: +/- 1% FSH.

  • Amplifier Linearity: +/- 1 dB.

  • Amplitude Measurement: 0 to 100% FSH, with 1% resolution.

  • Delay: 0 – 999.999in (25,400mm) at steel velocity.

  • Measurement Gates: Three independent gates depending on measurement mode selected, with audible and visual alarms. Amplitude 5-95%, 1% steps.


  • Units: English (in), Metric (mm), or Time (µs).

  • Velocity: 0.0492 to .5510 in/µs (1250–13995 m/s).

  • Measurement Modes: Pulse-Echo (P-E), Echo-Echo (E-E), or Echo-Echo-Echo (E-EV).

  • Measurement Range: 1 to 999.999in (2540cm) in pulse-echo(P-E) measurement mode. Range will vary using multi-echo modes – dependent on material type and consistency.

  • Detection: Zero Crossing.

  • Resolution: +/- 0.00001 in (0.0001 mm).

  • Calibration: Automatic, Fixed, Single or Two-Point zero calibration options.

  • Quantities:Time – Nanoseconds.Elongation – Change in length (inches/millimeters).Load – Force load applied (pounds KIP or megapascals MPa).Stress – Force for unit area stress applied (inches per inch or millimeters per millimeter).%Strain – Ratio of elongation to effective length.

  • Bolt Materials: Select types from a preset or custom list.



  • Factory calibration traceable to NIST & MIL-STD-45662A.

  • 2 year limited warranty.

Brochure Download - Dakota MAX II

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