The Dakota BT2-DL Max II is the ultrasonic bolt tension monitor in benchtop version with multi-channel capability. Simultaneous measurement of several bolts, extended datalogger and large display.
- Benchtop: For laboratory and production
- Multi-channel: Measures several bolts together
- Extended datalogger: Structured storage of tightening data
- Large display: High-contrast reading
- Automatic calibration: On bolt length
- Elongation measurement: Precise ultrasonic technique
- P/N Z-197-0001: Official Dakota code
The Dakota BT2-DL Max II is the top-of-the-range ultrasonic bolt tension monitor in benchtop version, designed for multi-channel applications where simultaneous measurement on several bolts is required. A laboratory and production instrument for tightening control with full traceability and a large display, the reference instrument for activities requiring a high throughput of tightening checks.
Distinctive features include the multi-channel capability for simultaneous measurement of several bolts, the extended datalogger with structured organisation of tightening data, automatic calibration on bolt length, the high-contrast large display and the USB output. Compatible with dedicated magnetic-contact and standard-coupling probes. Dedicated software manages structured measurement campaigns.
Indicato per collaudo serraggio in linea di produzione, controllo qualità di componenti motore, turbine, flange critiche e strutture industriali. Disponibile presso RODER SRL, distributore ufficiale Dakota NDT, con taratura, riparazione e supporto tecnico dedicato. P/N Z-197-0001, soluzione di riferimento. Indicato anche per laboratori e qualifica componenti critici.
The Dakota BT2-DL (trade name Max II, P/N Z-197-0001) is the top-of-the-range Dakota NDT benchtop bolt tension monitor. It offers all the functions of the portable BT1-DL model with extended hardware performance designed for professional certified assembly applications: 3 pulser types (Spike, Square Wave, Tone Burst), voltage up to 400V, the ability to measure fasteners up to 100 feet (about 30 metres) in length, 3 independent gates, Lithium-Ion battery supplied as standard with 18 hours of battery life. Accuracy of ±0,0001 mm on elongation, compatible with BT1-DL workflows for integrated field-laboratory processes.
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Positioning within the Dakota Bolt Tension range
The Dakota Bolt Tension Monitor range comprises two complementary models:
- BT1-DL MiniMax portable (383 g, 3 × AA) — field inspections, 1 gate, 1 pulser (Square Wave 100-200V)
- BT2-DL Max II benchtop (2,04 kg, Li-Ion or 6 × AA) — certified assembly, 3 gates, 3 pulsers (Spike/Square/Tone Burst) up to 400V, fasteners up to 30 metres
The BT2-DL is the obligatory choice when you need: very long bolts (tie rods, tie bars of large structures), particularly attenuating materials (requiring Tone Burst to concentrate energy in a narrow band), multiple gates for complex analyses, or maximum battery life (18 hours with the Li-Ion pack). BT1/BT2 data are fully interoperable via the PC Utility software — allowing integrated workflows between the assembly site (BT2) and field monitoring (BT1).
When to choose the Dakota BT2-DL
- Very long bolts: structural tie rods, through bars, fasteners up to 30 metres
- Attenuating bolt materials: special steels, superalloys, austenitic stainless steels — requiring Tone Burst
- Certification of critical assemblies: nuclear, aerospace, offshore
- Large tie-rod structures: cable-stayed bridges, domes, pressure vessels
- Research & Development on special fasteners with pulser/gate flexibility
- Precision assembly in production: bench instrumentation with a large display
- Training and certification: fastener metrology laboratories
- Need for 3 independent gates for advanced waveform analysis
- Continuous work sessions of over 12 hours (18h Li-Ion pack)
Distinctive features compared with the BT1-DL
Documentation download
Official Dakota NDT technical documentation. Files open in a new tab.
 | BT2-DL Datasheet | Datasheet |
| BT2-DL User Manual | Manual |
| Letter of conformity — FX81-DL / BT2-DL | Conformity |
| EMC test report (EN — Europe) — FX81-DL / BT2-DL | EMC EN |
| EMC test report (FCC — USA) — FX81-DL / BT2-DL | EMC FCC |
- 3 pulser types (vs. 1 on the BT1): Spike, Square Wave, Tone Burst
- Voltage up to 400V (vs. 200V max on the BT1) — greater penetration
- Tone Burst at 5 frequencies: 0,5 / 1 / 2 / 5 / 10 MHz
- 3 independent gates (vs. 1 on the BT1)
- Tone Burst pulse width: from 50 ns to 1 μs (adjustable)
- Fasteners up to 30 metres (vs. the BT1 standard range)
- Lithium-Ion pack supplied as standard — 18h battery life
- Alternative power supply 6 × AA
- Benchtop form factor: larger display, bench ergonomics
- USB Type-A/Type-B (standard USB)
The three pulsers: when to use them
Spike 40 ns (up to 400V in HV mode)
Very short, high-energy pulse — maximum time resolution. Used for standard bolts where the back-wall echoes on short threads need to be identified precisely.
Square Wave 80-400 ns
Square wave with adjustable pulse width and HV (high voltage) versions up to 400V. Allows the energy to be matched to the probe frequency to optimise the signal-to-noise ratio on long bolts.
Tone Burst 50 ns – 1 μs
Pulse train at the nominal frequency of the probe (selectable 0,5 / 1 / 2 / 5 / 10 MHz). It concentrates the energy in a narrow band around the probe resonance — the only effective solution for bolts in highly attenuating materials or of very great length. This function clearly sets the BT2-DL apart in the bolt tension monitor market.
Main features
- Accuracy ±0,0001 mm
- Fasteners up to 30 metres (100 feet)
- 5 quantities: elongation, time (ns), load, stress, %strain
- 3 pulser types: Spike, Square Wave, Tone Burst
- Pulser voltage 100-400V
- 11 pulse options: Spike, Thin, Wide, HV Spike, HV Thin, HV Wide, TB 0.5/1/2/5/10 MHz
- 3 independent gates with audible/visual alarms, width 5-95%
- Adjustable damping 50/75/100/300/600/1500 Ω
- Broadband filter 1,8-19 MHz (-3 dB)
- TCXO 100 MHz 8 bit digitiser single-shot
- 64 custom setups user + editable factory setups
- Auto Set for automatic setup for each bolt
- Field Calibration Vector/Regression
- Alarm Limits Hi/Low with LED and buzzer
- Glue-On mode for short bolts
- Bolt materials preset + custom
- Linearity horizontal ±0,4% FSW, vertical ±1% FSH
- Li-Ion pack as standard (18h) or 6 × AA (12h alkaline)
- USB Type-A/Type-B
- Traceable NIST certificate as standard
- Benchtop form factor, larger display
Technical specifications
| Parameter | Value |
| Part Number | Z-197-0001 |
| Trade name | Max II |
| Form factor | Benchtop |
| Accuracy | ±0,0001 mm (±0,00001″) |
| Maximum fastener length | 30 metres (100 feet) |
| Measured quantities | Elongation, Time (ns), Load, Stress, %Strain |
| Pulser types | Spike / Square Wave / Tone Burst |
| Pulser voltage | 100 – 400V |
| Pulse options | Spike 40 ns, Square Wave 80-400 ns, Tone Burst 50 ns – 1 μs |
| Tone Burst frequencies | 0,5 / 1 / 2 / 5 / 10 MHz |
| Damping | 50 / 75 / 100 / 300 / 600 / 1500 Ω |
| Broadband filter | 1,8 – 19 MHz (-3 dB) |
| Gates | 3 independent, audible+visual alarms |
| Gate width | 5-95% in 1% steps |
| Delay | 0 – 25.400 mm (steel velocity) |
| Digitiser | TCXO 100 MHz 8 bit single-shot |
| Horizontal linearity | ±0,4% FSW |
| Vertical linearity | ±1% FSH |
| Amplifier linearity | ±1 dB |
| Field calibration | Vector / Regression |
| Setups | 64 user-definable + editable factory setups |
| Auto Set | Yes |
| Glue-On | For short bolts |
| Bolt materials | Preset + custom |
| Power supply | Lithium Ion pack (supplied) or 6 × AA |
| Battery life | Li-Ion 18h / Alkaline 12h / NiCd 5h / NiMH 12h |
| Data output | USB Type-A/Type-B |
| Operating temperature | -10 ÷ +60 °C |
| Weight | 2,04 kg (incl. batteries) |
| Dimensions | 216 × 165 × 70 mm |
Comparison BT1-DL vs BT2-DL
| Feature | BT1-DL MiniMax | BT2-DL Max II |
| Part Number | Z-156-0008 | Z-197-0001 |
| Form factor | Portable | Benchtop |
| Weight | 383 g | 2,04 kg |
| Accuracy | ±0,0001 mm (identical) | |
| Fastener length | Standard | Up to 30 metres |
| Pulser types | 1 (Square Wave) | 3 (Spike, Square, Tone Burst) |
| Pulser voltage | 100/150/200V | 100-400V |
| Gates | 1 | 3 independent |
| Batteries | 3 × AA (35h) | Li-Ion (18h) / 6 × AA (12h) |
| USB | USB-C | USB-A/B |
| Ideal scenario | Field, periodic monitoring | Certified assembly, long bolts, attenuating materials |
Compatible probes
The BT2-DL uses Dakota single element bolt tension probes in the 0,5 – 10 MHz frequency range supported by the Tone Burst. For long bolts or attenuating materials, low-frequency probes (0,5 – 2 MHz) with a large-diameter element are typically used. The choice of probe depends on length, bolt head diameter, material and type of coupling:
- Manual coupling with couplant — one-shot measurements
- Magnetic coupling — ferromagnetic bolts
- Glue-On — transducer disc permanently bonded for periodic monitoring
The standard kit includes a 10′ LEMO-00 to Microdot cable. For advice on the optimum probe, contact us.
Typical applications
- Certified assembly of pressure vessels (flanged bolts according to ASME PCC-1)
- Large tie-rod structures: cable-stayed bridges, domes, industrial roofs
- Nuclear sector: containment bolts with absolute certification
- Aerospace: critical structural connections
- Power generation: turbines, generators with long through bolts
- Large industrial engines: marine engines, railway diesel engines
- Wind energy sector: special fasteners on modern structures
- Heavy machinery: presses, rolls, forming plants
- Metrological research on innovative fasteners
- Technician training on the bolt tension method
Recommended application guides:
- ASME PCC-1: the reference standard for controlled flange bolting
- Bolt tension in wind turbines: the ultrasonic method with Dakota
- Ultrasonic measurement vs torque wrench in bolt tightening
- How to improve results on difficult materials
Scope of supply
- Dakota BT2-DL Max II instrument
- Lithium Ion pack (supplied as standard)
- 4 oz bottle of ultrasonic couplant
- USB Type-A / Type-B cable for data transfer
- 10′ LEMO-00 to Microdot probe cable
- Rigid carrying case
- PC Utility software (download)
- Operating manual
- NIST-traceable calibration certificate
Note: the probe is not included. For optimum sizing according to bolt length and material, contact us.
Standards and certifications
- NIST-traceable factory calibration
- MIL-STD-45662A conformity
- CE marking and EMC conformity
- ASME PCC-1 compatibility
- Calibration certificate supplied as standard
Frequently asked questions
It is not just the form factor. The BT2-DL adds operating capabilities that the BT1-DL does not have: 3 pulser types (with Tone Burst for attenuating materials), voltage up to 400V, 3 independent gates, fasteners up to 30 metres. If you have standard bolts of normal length in common steels, the BT1-DL is fully adequate. If you have long tie rods, bolts in superalloys or attenuating materials, the BT2-DL is necessary.
The Tone Burst generates a pulse train at the nominal frequency of the probe, concentrating energy in a narrow band around the resonance. This dramatically improves the signal-to-noise ratio on bolts in materials that attenuate or scatter ultrasound (superalloys, highly attenuating stainless steels, very long bolts where the signal weakens along the round-trip path). Without Tone Burst some measurements would not be physically possible.
For very long bolts the BT2-DL combines: a high-voltage pulser (up to 400V for sufficient energy), low-frequency Tone Burst (0,5 – 1 MHz for penetration) and low-frequency probes with a large-diameter element. The 3 independent gates make it possible to discriminate between the multiple echoes that can appear on such long ultrasonic paths. The operator must have specific experience — in these applications technical advice is essential.
The BT2-DL is powered by the included Lithium Ion pack (18h battery life) or alternatively by 6 AA batteries. For stationary indoor use it can be charged continuously or powered via USB during operation — extending the battery life indefinitely.
Yes. Both use the same Dakota PC Utility software and generate interoperable data files. This allows integrated workflows: initial assembly with the BT2-DL in the workshop (certified traceability) followed by periodic monitoring with the BT1-DL in the field (routine inspections) — with all data flowing into the same technical archive.
Request a customised quotation for the Dakota BT2-DL
We will support you in sizing the complete system (probe + accessories + calibration curves) according to your sector and your critical bolts. Contact us for dedicated technical advice.