Dakota ZX6-DL – Multi-Echo Thickness Gauge with Data Logger

The Dakota ZX6-DL is the flagship model in the ZX series of Dakota NDT ultrasonic thickness gauges, designed for corrosion inspection in demanding industrial environments. It combines the standard Pulse-Echo mode and the Multi-Echo Through-Paint mode — the latter making it possible to measure the base metal thickness while eliminating the coating error, without having to remove it. With a built-in data logger for 10,000 readings, adjustable gain, automatic TDG (Time Dependent Gain) and a 4.5-digit LCD display readable in direct sunlight, the ZX6-DL is the reference instrument when repeatable and traceable measurement is required in the periodic inspection of tanks, boilers, piping and structures subject to uniform corrosion.

Positioning within the Dakota ZX range

The Dakota ZX series is the line of basic corrosion thickness gauges designed to deliver reliable measurement without requiring specialist training. It comprises four models with increasing capability:

• Dakota ZX1 — pre-calibrated for steel, manual velocity adjustment, Pulse-Echo range 1.5-200 mm (P/N Z-300-0003)
• Dakota ZX3 — extended Pulse-Echo range 0.63-914.4 mm with scan mode (P/N Z-302-0003)
• Dakota ZX5-DL — adds a 10,000-reading sequential data logger (P/N Z-304-0003)
• Dakota ZX6-DL — top of the range with Echo-Echo Through-Paint mode and data logger (P/N Z-306-0003)

The ZX6-DL is the only model in the ZX series that includes Echo-Echo mode, essential for accurate measurement on painted or coated surfaces without having to remove the protective layer. All ZX models are housed in an extruded aluminium body to withstand the harshest environments and are covered by a 5-year manufacturer’s warranty.

When to choose the Dakota ZX6-DL

The ZX6-DL is the ideal choice when:

• You need to inspect painted or coated surfaces (storage tanks, industrial piping, marine components) and removing the coating is not possible or not practical
• You need structured archiving of measurements for reporting and for comparison between periodic inspections
• You work in environments with strong sunlight or poor visibility, where a high-contrast LCD is more dependable than an OLED
• You are looking for a rugged extruded aluminium instrument intended for field use by non-specialist personnel
• You do not need graphical A-Scan or B-Scan, but you do need repeatable numerical readings

If instead you need A-Scan display or advanced corrosion measurement modes (EE-V, PE-TP, CT), consider the Dakota CMX series or the CMX10-DL. For a detailed comparison with the Dakota CMX range, see our guide ZX-3 vs CMX1-DL.

Main features

• Two measurement modes: Pulse-Echo (PE) for unpainted surfaces and Multi-Echo Through-Paint (EE) for coated surfaces
• Built-in data logger: sequential archiving of 10,000 readings organised in 40 files of 250 readings each
• Automatic TDG (Time Dependent Gain) in both measurement modes
• Adjustable gain to suit difficult materials or irregular surfaces
• Extended measurement range: 0.63-914.4 mm in PE, 2.54-152.4 mm in EE
• LCD display, 12.7 mm digits, 4.5 digits, with selectable LED backlight (on/off/auto)
• Repeatability indicator and real-time measurement stability
• High-speed scan mode for continuous measurement
• Differential mode for comparison against a nominal thickness
• Limit alarm mode with audible/visual signalling when the threshold is exceeded
• Correzione V-path/dual-path automatica
• Manual or automatic Probe Zero using the built-in zeroing disc
• Rugged extruded aluminium body
• 5-year warranty from the manufacturer Dakota NDT
• Calibration certificate supplied as standard

Full technical specifications

Parameter	Value
Part Number	Z-306-0003
Measuring mode	Pulse-Echo (PE) + Multi-Echo Through-Paint (EE)
PE measuring range	0.63 – 914.4 mm (0.025 – 36″)
EE measurement range	2.54 – 152.4 mm (0.100 – 6.0″)
Resolution	0.01 mm (0.001″)
Velocity calibration range	305 – 18,542 m/s (0.0120 – 0.7300 in/μs)
Transducer type	Dual element
Transducer frequency range	1 – 10 MHz
V-path correction	Automatic
Probe Zero	Manual or automatic
Memory / Data Logging	10,000 readings in 40 files of 250 readings each
Scan mode	High-speed scan
Differential mode	Yes
Limit alarm mode	Yes
Repeatability/stability indicator	Yes
Display	LCD 12.7 mm (1/2″), 4.5 cifre
Backlight	Selectable LED (on/off/auto)
Units of measurement	mm / inches (selectable)
Operating temperature	-30 ÷ +75 °C (-22 ÷ +167 °F)
Power supply	2 AA batteries
Battery life	35 hours (alkaline) / 23 hours (NiCd)
Weight	312 g (11 oz) including batteries
Dimensions	63.5 × 131 × 31.5 mm (2.5 × 5.17 × 1.24″)
Warranty	5 years, manufacturer

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Measurement modes: Pulse-Echo and Multi-Echo Through-Paint

Pulse-Echo (PE)

Pulse-Echo mode is the classic ultrasonic method: the transducer emits a pulse that travels through the material, reflects off the opposite surface (back-wall) and returns to the transducer. The time of flight divided by the sound velocity in the material gives the thickness. The ZX6-DL offers a very wide range — from 0.63 to 914.4 mm — covering most industrial applications, from thin alloy tube to heavy structural steel plate.

Multi-Echo Through-Paint (EE)

Echo-Echo Through-Paint mode measures the base metal thickness even on painted or coated surfaces, eliminating the error introduced by the coating. The principle: the instrument detects two consecutive back-wall echoes and calculates the time difference, which corresponds to a double pass through the metal alone. The coating (up to a few millimetres) is automatically excluded. This avoids having to scrape or remove protective paint — a considerable operational advantage for maintenance inspection on painted tanks, insulated piping with external coatings, ship hulls. To understand how this technology works, see our dedicated guide to Echo-Echo and ThruPaint™.

Typical applications

• Corrosion and pitting inspection on in-service metal components
• Storage tanks (painted or insulated)
• Boilers and steam generators
• Piping and pipelines (oil, gas, steam, process water)
• Glass surfaces (chemical industry, packaging)
• Marine and offshore sector: hulls, load-bearing structures, platforms
• Petrochemical industry: periodic asset monitoring to API 570/653
• Predictive maintenance in industrial plants

For application detail we suggest these technical guides:

• Uniform corrosion monitoring: methods, instruments and standards
• How to measure the thickness of tubes and piping with an ultrasonic gauge
• Data logger vs manual recording: why NDT readings should be archived
• API 570 and API 653: instrumentation requirements for piping and tank inspection

Scope of supply

The Dakota ZX6-DL is supplied with the following standard kit:

• Dakota ZX6-DL instrument
• Ultrasonic transducer of choice (dual element)
• Ultrasonic couplant
• User manual
• Rigid carrying case
• Calibration certificate traceable to NIST and MIL-STD-45662A
• 2 AA batteries
• DakMaster™ PC software for downloading, archiving and managing measurements
• PC data transfer cable

To make the most of the ZX6-DL data logger, see our guide DakMaster™: managing and archiving NDT measurements on PC.

For more on choosing the probe: probes for corrosion gauges and the guide How to choose the right ultrasonic transducer. For a quotation, please state the order code and quantity.

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Documentation download

Official Dakota NDT technical documentation. Files open in a new tab.

	ZX6-DL datasheet	Datasheet
	ZX6-DL user manual	Manual

Standards and certifications

• Factory calibration traceable to NIST (National Institute of Standards and Technology, USA)
• MIL-STD-45662A compliance (Military Standard Calibration Systems Requirements)
• CE marking with certificates of conformity (FCC ICES, EN 61326)
• EN 14127 compliance (Non-destructive testing – Ultrasonic thickness measurement)
• ASTM E797 compliance (Standard practice for measuring thickness by manual contact ultrasonic methods)

For detail on the standards applying to ultrasonic thickness measurement see the guide NDT standards for thickness measurement: EN 14127, ASTM E797 and EN 15317.

Frequently asked questions

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