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The Dakota BT1-DL Bolt Tension Monitor (part number Z-156-0008), also known as the MiniMax, is a handheld ultrasonic gauge that measures fastener elongation, time in nanoseconds, load, stress and percentage strain. When a nut and bolt are tightened together, the rising clamp force stretches the bolt. Standard torque methods are affected by temperature, friction and other resistance factors that can mask the true load, whereas ultrasonic measurement is not, giving the BT1-DL accuracy within 0.0001mm.
The Dakota BT1-DL Bolt Tension Monitor sends an ultrasonic pulse along the bolt and measures the change in its length as load is applied. It covers a measurement range of the Dakota BT1-DL Bolt Tension Monitor from 25.4mm to 25,400mm in pulse-echo mode, with switchable resolution of 0.001mm or 0.0001mm and a velocity calibration range of 1250 to 13,995m/s. Readings appear on a 1/8 inch VGA greyscale display and update at up to eight per second. An Auto Set function automates detection, scope and display setup for each bolt, and field calibration can use a vector or regression correction curve based on load and stress for increased accuracy.
Data is held in 4GB of internal memory with sequential and grid batching, and the Dakota BT1-DL Bolt Tension Monitor weighs 383g including batteries. A glue-on option suits short bolts with minimal elongation to remove transducer placement errors. Factory calibration of the Dakota BT Bolt Tension Monitor is traceable to NIST and MIL-STD-45662A. The Dakota BT1-DL Bolt Tension Monitor is used on wind turbines, automotive frames, bridge structures and similar bolted assemblies, and is supplied by BAMR, South Africa's authorised distributor.
Dakota BT Bolt Tension Monitor
The Dakota BT Bolt Tension Monitor uses ultrasound to precisely measure fastener elongation, time (nanoseconds), load, stress & %strain. By using ultrasonics, bolt tension monitors are not affected by temperature, friction or resistance factors affecting the accuracy of standard torque measurement techniques - giving the Dakota BT1-DL Bolt Tension Monitor accuracy within 0.0001mm.
- Material thickness digits display
- A-Scan Rectified +/- (half wave view), or RF (full waveform view)
- Temperature Compensation
- Limit Alarm Mode
- Memory and Data Logging 4GB internal memory, sequential and grid batching, bitmap graphic capture and capture viewer
- Temperature Compensation
- Repeatability / Stability Indicator
- Low Battery Indicator
- USB-C Interface
- Auto Set Automates the detection, scope, and display setting process for each individual bolt
When to use the Dakota BT Bolt Tension Monitor
Use the handheld BT when you need accurate fastener tension in the field and torque methods are letting you down. It uses ultrasound to measure elongation, load, stress and strain, and because it reads sound rather than turning effort it is not thrown off by temperature, friction or resistance.
- 1Accuracy torque cannot matchUltrasonic measurement is not affected by temperature, friction or resistance, giving accuracy within 0.0001mm where torque-only methods carry hidden error.
- 2Full tension pictureIt reports elongation, time in nanoseconds, load, stress and percentage strain, so you understand the joint rather than just a single tightness number.
- 3Built for field useAt 383g with 35 hours of alkaline battery life and 4GB logging memory, it is sized to carry round a site and record results as you go.
- 4Auto setup per boltAuto Set handles detection, scope and display for each individual bolt, which speeds up work when you are measuring many fasteners in sequence.
Lower-budget alternatives
Ten minutes on a call with one of our specialists usually saves you from buying the wrong instrument.
Book a 10-minute callOr , our product assistant, for an instant answer.
When to use this
When to use the Dakota BT Bolt Tension Monitor
Use the handheld BT when you need accurate fastener tension in the field and torque methods are letting you down. It uses ultrasound to measure elongation, load, stress and strain, and because it reads sound rather than turning effort it is not thrown off by temperature, friction or resistance.
- 1Accuracy torque cannot matchUltrasonic measurement is not affected by temperature, friction or resistance, giving accuracy within 0.0001mm where torque-only methods carry hidden error.
- 2Full tension pictureIt reports elongation, time in nanoseconds, load, stress and percentage strain, so you understand the joint rather than just a single tightness number.
- 3Built for field useAt 383g with 35 hours of alkaline battery life and 4GB logging memory, it is sized to carry round a site and record results as you go.
- 4Auto setup per boltAuto Set handles detection, scope and display for each individual bolt, which speeds up work when you are measuring many fasteners in sequence.
Lower-budget alternatives
Ten minutes on a call with one of our specialists usually saves you from buying the wrong instrument.
Book a 10-minute callOr , our product assistant, for an instant answer.
Specifications
Technical Specifications
| Part Number | Description | Certificate |
|---|---|---|
| Z-156-0008 | Dakota BT1-DL Bolt Tension Monitor (MiniMax) | ♦ |
| Operating Temperature | -10 to 60ºC |
- Power Supply
- 3 x AA batteries and via USB
- Battery Life
- Alkaline 35 hrs, Nicad 10 hrs, NI-MH 35 hrs
- Gauge Weight
- 383g – including batteries
- Gauge Dimensions
- 63.5 x 165 x 31.5mm
- Model
- BT1-DL
- Material thickness digits display
- Yes
- A-Scan
- Rectified +/- (half wave view), or RF (full waveform view)
- Display
- 1/8" VGA greyscale display (240 x 160 pixels), viewable area 62 x 45.7mm
- Units (Selectable)
- mm, μs, °C
- LED Backlight
- On / Off / Auto
- Screen Refresh Rate
- 30 Hz
- Measurement Range
- PE - 25.4 - 25,400mm
- Resolution
- 0.001mm or 0.0001mm switchable
- Measurement Rate (Manual)
- 8 readings per second
- Velocity Calibration Range
- 1250 - 13,995m/s
- Detections
- Zero Crossing
- Time
- Nanoseconds
- Elongation
- Change in length (mm)
- Load
- Force load applied (pounds KIP, or megapascals MPa)
- Stress
- Force for unit area stress applied (millimeters per millimeter)
- %Strain
- Ratio of elongation to effective length
- Calibration Options
- Automatic, fixed, single and two-point
- Field Calibration
- Vector or Regression correction curve for increased accuracy using Load & Stress
- Setups
- 64 custom user defined setups; factory setups can also be edited by the user
- Alarm Limits
- Adjustable Hi/Low tolerances with visual LED's and audible beeper
- Alarm Limits Bar
- Hi & Lo alarm limits for displaying an acceptable tolerance range
- Measurement Gate
- One gate with audible and visual alarm. Amplitude 5-95%, 1% steps
- Transducer Probe Type
- Single element
- Transducer Frequency Range
- 1 - 10MHz
- Transducer Connector Type
- Microdot, Lemo and BNC
- Timing
- Precision TCXO timing with single shot 100 MHz 8 bit ultra-low power digitizer
- Pulser Type
- Square Wave. Selectable 100, 150 and 200 volts. Selectable options Spike, Thin, and Wide. 80 to 400ns
- Damping
- 50, 75, 100, 300, 600, & 1500ohms
- 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
- 25,400 mm at steel velocity
- Memory and Data Logging
- 4GB internal memory, sequential and grid batching, bitmap graphic capture and capture viewer
- USB-C Interface
- Yes
- Temperature Sensor
- 5 pin LEMO 1
- Battery Save Mode
- Auto
- Bolt Materials
- Select types from a preset or custom list
- Accessories
- N-306-0010
- USB to Serial Adapter
- N-402-0510
- USB-C to USB TYPE A 1m data cable
- N-003-0330
- Temperature Sensor with 1.8m cable
- A-156-8001
Packing List
Packing List
Standards
Standards
Accessories
Accessories
| 1.8m RS232 ( DB-9 to lemo ) |
| USB-C to USB TYPE A 1m data cable |
| Temperature Sensor with 1.8m cable |
Part Numbers
Part Numbers
| Description | Part Numbers |
|---|---|
| Dakota BT1-DL Bolt Tension Monitor (MiniMax) | Z-156-0008 |
Frequently asked questions
What parameters does the Dakota BT1-DL Bolt Tension Monitor measure?
It measures fastener elongation, time in nanoseconds, load (in pounds KIP or megapascals), stress (force per unit area, millimetres per millimetre), and percent strain (ratio of elongation to effective length).
Why is ultrasonic bolt tension measurement more accurate than torque-based methods?
Ultrasonics are not affected by temperature, friction, or resistance factors that affect the accuracy of standard torque measurement techniques. The Dakota BT1-DL achieves accuracy within 0.0001mm.
What are the measurement range and resolution of the BT1-DL?
In Pulse Echo mode the measurement range is 25.4 to 25,400mm. Resolution is switchable between 0.001mm and 0.0001mm.
How is the Dakota BT1-DL powered and what is its battery life?
It runs on 3 x AA batteries or via USB. Battery life is approximately 35 hours with alkaline or NI-MH batteries, and 10 hours with NiCad batteries.
What data logging and calibration capabilities does the BT1-DL offer?
It has 4GB internal memory with sequential and grid batching. It supports 64 custom user-defined setups. Calibration options include automatic, fixed, single and two-point methods, plus Vector or Regression correction curves using load and stress.
What transducer connector types does the BT1-DL accept?
The BT1-DL accepts Microdot, Lemo, and BNC transducer connectors, with a transducer frequency range of 1 to 10MHz.
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Tell us about your application and we will send a quote with lead time and accessories.