The Dakota PMX4-DL is the ultrasonic High Penetration gauge designed for difficult materials: composites, plastics, rubber and castings. Extended data logger and high transmission energy.
- High Penetration : For attenuating materials
- Extended data logger : Memory for thousands of readings
- 0.001 mm resolution : Precision on thin materials
- Echo-Echo : Measurement through coatings
- 2-point calibration : Accuracy in every application
- A-Scan : Waveform display
- P/N Z-225-0002 : Official Dakota code
The Dakota PMX4-DL is the ultrasonic thickness gauge of the Precision family dedicated to difficult materials: fibre composites, plastics, rubber, castings and highly attenuating alloys. The high transmission energy allows stable readings where other instruments cannot operate. A proven instrument in applications where other standard gauges cannot deliver stable readings.
Its distinguishing features include High Penetration mode for strongly attenuating materials, an extended data logger, A-Scan display, 0.001 mm resolution and two-point calibration with sound velocity compensation. Compatible with low-frequency Dakota probes dedicated to penetration on composites and rubber. Dedicated software allows detailed reports for the certification of composite products.
High Penetration Thickness Gauge
Suitable for inspections on aeronautical composites, automotive parts in plastic and rubber, alloy castings and polymer materials. Available from RODER SRL, official Dakota NDT distributor, with dedicated calibration, repair and technical support. P/N Z-225-0002, a solution for advanced applications. Also suitable for quality control of ballistic panels and advanced engineered materials.
The Dakota PMX4-DL (also known as HPX DL+) is the high-penetration thickness gauge of the Dakota NDT specialty range. It is designed specifically for materials that are difficult to penetrate because of inconsistencies in their structure, coarse grain or high thickness. With multiple high-voltage pulser options (Spike 200V, Square Wave 400V, Tone Burst 400V), filters optimised for low-frequency probes 500 kHz – 10 MHz and a measuring range up to 30.500 mm (30 metres) on steel in PE mode, it is the reference instrument for ductile iron, highly attenuating alloy steels, composite materials, reinforced concrete, thick plastic and components in difficult service conditions.
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Positioning within the Dakota range
The PMX4-DL is classed among the Dakota Speciality Gauges — it is not a replacement for the PMX2/PMX3-DL but a complement to them for applications where standard gauges fail. The crucial difference from the other PMX models is the high-voltage excitation system and the probe frequency range shifted downwards (500 kHz instead of 25 MHz) to penetrate materials that absorb or scatter ultrasound.
- For standard precision applications (homogeneous metals, thin plastic): PMX2-DL / PMX3-DL
- For attenuating materials and large thicknesses: PMX4-DL (this instrument)
- For PTG inspections with wireless Bluetooth: PCX8-DL
- For the top of the corrosion range with colour A-Scan, B-Scan and Full Wave Capture: CMX10-DL
When to choose the Dakota PMX4-DL
- Ductile iron, grey iron, lamellar graphite iron: the coarse grain strongly attenuates the signal
- Highly attenuating austenitic stainless steels (distillation columns, chemical exchangers)
- Thick composite materials (laminates, sandwich panels, fibre-resins)
- Cement, reinforced concrete (scanning of thick sections)
- Thick plastic (up to 127 mm) and rubber
- Metal components with very high thicknesses (up to 30 metres on steel)
- Materials in difficult service conditions (internal rust, scale, advanced corrosion)
- Inspections where the standard PMX models cannot detect the back-wall echo
Distinguishing features compared with the PMX2-DL
- Spike 200V pulser for short pulses and high resolution
- Square Wave 400V pulser for energetic excitation with adjustable pulse width
- Tone Burst 400V pulser — unique in this segment — for controlled-frequency excitation on critical materials
- Probe frequency range 500 kHz – 10 MHz (vs. 1-25 MHz on the PMX2/PMX3) — optimised for low frequencies, which penetrate better
- Dedicated filters for low-frequency probes
- Time Dependent Gain (TDG) with variable start and slope to compensate for progressive attenuation with depth
- PE range on steel extended to 30.5 metres (vs. 9.1 metres on the PMX2/PMX3)
- Greyscale display (not available in a colour version)
Documentation downloads
Official Dakota NDT technical documentation. Files open in a new tab.
 | PMX4-DL datasheet | Datasheet |
| PMX4-DL user manual | Manual |
Supported measurement modes
| Mode | Range | Typical use |
| PE contact (steel) | 1,27 – 30.500 mm | Attenuating materials, high penetration |
| PE contact (plastic) | 2,54 – 127 mm | Thick plastics, rubber |
| EE contact (steel) | 2,54 – 914,4 mm | Painted surfaces |
| EEV contact (steel) | 2,54 – 152,4 mm | Consistency check between multiple echoes |
Note: the PMX4-DL is optimised for penetration. Unlike the PMX2/PMX3, it does not support the Interface-Echo (IE/IEE) modes for thin thicknesses below 1 mm, because its purpose is the opposite: measuring large thicknesses or attenuating materials.
Key features
- 3 pulser types (Spike 200V, Square Wave 400V, Tone Burst 400V) — all with adjustable pulse width and voltage
- Filters tuned for low frequencies 500 kHz – 10 MHz
- Time Dependent Gain (TDG) — compensates for attenuation with depth
- AGC gain 110 dB with adjustable damping 35-1500 Ω
- TCXO 100 MHz 8 bit digitizer single-shot
- 4 GB memory with sequential and grid logging
- Alphanumeric batch IDs with OBSTRUCT flag
- 64 user setups transferable to/from a PC
- Selectable resolution 0,1 mm or 0,01 mm
- Scan mode 250 readings/sec
- 1/8 VGA greyscale display with sunlight assist
- Bitmap capture
- Limit alarm mode for pass/fail
- Repeatability/stability indicator + low battery
- Hybrid power supply 3 × AA + USB
- DakMaster™ software supplied as standard
Full technical specifications
| Parameter | Value |
| Part Number | Z-225-0002 |
| Alternative designation | HPX DL+ |
| Display modes | Digits, Scan Bar, B-Scan, Combined B-Scan+digits, A-Scan (RF/Rect+/Rect-) |
| PE range steel | 1,27 – 30.500 mm |
| PE range plastic | 2,54 – 127 mm |
| EE range steel | 2,54 – 914,4 mm |
| EEV range steel | 2,54 – 152,4 mm |
| Resolution | ±0,1 mm / ±0,01 mm selectable |
| Manual rate | 8 readings/sec |
| Scan rate | 250 readings/sec |
| B-Scan display rate | 10 – 200 readings/sec |
| Calibration setups | 64 user-definable |
| Gate | 3 adjustable |
| Spike pulser | 200V, adjustable pulse width |
| Square Wave pulser | 400V, adjustable pulse width |
| Tone Burst pulser | 400V, adjustable pulse width |
| Gain | Manual or AGC, 110 dB range, TDG with variable start/slope |
| Damping | 35 / 50 / 75 / 300 / 600 / 1500 Ω |
| Digitizer | TCXO 100 MHz 8 bit single-shot ultra-low power |
| Memory | 4 GB |
| Logging | Sequential and grid, alphanumeric IDs, OBSTRUCT |
| Calibration options | Single, two-point, velocity, material type |
| Probe type | Single element with delay tip, pencil with delay tip, contact |
| Probe frequency range | 500 kHz – 10 MHz |
| Probe recognition | Manual (from a list) |
| Display | 1/8 VGA greyscale, 62 × 45,7 mm |
| Backlight | LED (on/off/auto) |
| Repeatability indicator | Yes |
| Low battery indicator | Yes |
| Power supply | 3 × AA and/or via USB |
| Battery life | 35h alkaline / 10h NiCd / 35h NiMH |
| Operating temperature | -10 ÷ +60 °C |
| Weight | 383 g (with batteries) |
| Dimensions | 63,5 × 165 × 31,5 mm |
The three pulsers: when to use them
Spike 200V
Short, high-energy pulse — ideal when high temporal resolution is required with broadband probes. Typical use: thickness measurement in steel at high penetration, where accuracy on the back-wall position is critical.
Square Wave 400V
Square-wave excitation with 400V peak voltage and adjustable pulse width. It allows the pulse to be tuned to the probe frequency in order to maximise the return signal at depth. Typical use: ductile cast iron and alloy steels, where the coarse grain scatters the signal.
Tone Burst 400V
The most sophisticated pulser: it generates a burst of pulses at the nominal frequency of the probe, concentrating the energy in a narrow band. Excellent for highly attenuating materials (composites, thick rubber, reinforced concrete) where maximum usable energy is needed within the band of interest. This capability is one of the most distinctive features of the PMX4-DL.
Compatible probes
The PMX4-DL supports Dakota single element probes in the 500 kHz – 10 MHz range. For high penetration, 1-5 MHz probes with a large-diameter element are typically used to concentrate energy. Supported types:
- Single element with delay tip for delay-line measurement applications
- Pencil probe with delay tip for restricted access
- Low-frequency contact probe (500 kHz – 2 MHz) for cast iron and attenuating materials
- Broadband contact probe for cross-material flexibility
For the best choice, please see How to choose the right ultrasonic transducer and How to improve results on difficult materials.
Typical applications
- Foundries: thickness measurement on ductile, grey and lamellar cast iron castings
- Chemical and petrochemical industry: distillation columns, austenitic stainless steel heat exchangers
- Large welded structures with high wall thicknesses
- Cement industry: thickness measurement on reinforced concrete structures
- Composite components: thick laminates, sandwich panels
- Rubber industry: rollers, hoses, thick rubber seals
- Thick plastic materials (up to 127 mm)
- Heavy marine sector: duplex stainless steel structures
- Power generation: inspection of components exposed to erosion/corrosion with attenuating material
- Research and development: characterisation of new materials
Recommended technical guides:
- How to improve results on difficult materials with an ultrasonic thickness gauge
- How to measure the thickness of pipes and tubing with an ultrasonic thickness gauge
- How to choose the right ultrasonic transducer
- How ultrasonic thickness measurement works: the basic principles
Scope of supply
- Dakota PMX4-DL instrument
- Probe cable
- Ultrasonic couplant
- Operating manual
- NIST-traceable calibration certificate
- 3 AA batteries
- Transit case
- DakMaster™ software (download) with data transfer cable
Note: the probe is NOT supplied as standard in the standard package. For correct sizing of the high-penetration probe according to your material, contact us for dedicated advice.
Standards and certifications
- NIST-traceable factory calibration
- MIL-STD-45662A compliance
- CE marking and EMC compliance
- EN 14127 compliance
- ASTM E797 compliance
Frequently asked questions
The PMX4-DL has a high-voltage pulser (up to 400V) and filters optimised for low-frequency probes (500 kHz). This makes it effective on materials that heavily attenuate ultrasound (cast iron, austenitic stainless steel, composites, concrete), where the PMX2-DL is unable to receive the return echo. The PMX4-DL is a specialist instrument: if your material is homogeneous steel, aluminium or thin plastic, the PMX2-DL remains more versatile.
The range declared by Dakota is 1.27 – 30,500 mm on steel in PE mode. In practice, the effective limit depends on: probe frequency and diameter, coupling surface, material condition and couplant used. 30 metres is the maximum theoretical limit; many high-penetration applications concentrate on the 100 mm – 2 metre range, where TDG and high-voltage pulsers make the difference.
Tone Burst generates a burst of pulses at the nominal frequency of the probe, concentrating the energy in a narrow band around the resonant frequency. It maximises the signal-to-noise ratio for low-frequency resonant probes, typically used for highly attenuating materials. It is a technique rarely available in portable instruments in this category.
No. Interface-Echo mode (IE/IEE) is specific to thin thicknesses and is available on the PMX2-DL / PMX3-DL. The PMX4-DL is dedicated to high penetration: its range of modes is PE, EE, EEV.
For ductile and grey cast iron, low-frequency single element contact probes (1-2 MHz) with a large-diameter element are typically used, in order to concentrate the energy and overcome the attenuation caused by the grain. The precise choice depends on the thickness to be measured and on the quality of the graphite. Contact us for advice on the best probe for your specific application.
Request a customised quotation for the Dakota PMX4-DL
We will assist you in configuring the instrument and choosing the high-penetration probe best suited to your material. Contact us for dedicated technical advice.
Further information and contacts
Systems division and sensor integration partner : www.roder.it
More information about RODER SRL : about us
Contact for general information : info@roder.it
Contact for information about these products : info@roder.it
The information contained on this web page is provided for information purposes only. Although it has been compiled with the utmost care, it does not constitute a contractual offer or a binding commitment to supply. It may contain transcription, translation or typographical errors. For precise and up-to-date information, please contact our company directly.
Some images on this website have been intentionally generated using Artificial Intelligence (AI). This is because, for many applications and projects, it is not possible to disclose photographs of the installation or of the actual system due to confidentiality agreements, confidentiality clauses and non-disclosure agreements (NDAs).