Among the features that separate an entry-level thickness gauge from a professional instrument, the internal data logger is one of the most important. A gauge with a data logger can store thousands of readings, each with its own identifier, and download them later for analysis and reporting. In this article we look at why electronic recording of readings has become the standard required by industrial regulations, and what the concrete benefits are compared with manual recording.
Problems with manual recording
Manual recording — the operator reads the value from the display and writes it on a paper sheet or a tablet — has well-known limitations:
- Transcription errors: studies show an error rate of 1-3 % on manual transcription of numerical values
- Slowness: every reading costs an extra 10-30 seconds for manual recording
- Ambiguity: measurement locations are identified from poorly structured notes
- Awkward archiving: paper sheets have to be digitised afterwards, with further risk of error
- No waveform: manual recording captures only the numerical value, not the associated A-Scan
- No integrity: there is no record of when a reading was actually taken
- Hard to compare over time: running trend analysis on years of manual data is practically impossible
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What the electronic data logger offers
A data logger built into the measuring instrument removes these problems and offers:
- Automatic recording: every reading is stored at a touch, with no transcription
- Structured identification: readings are organised into alphanumeric grids or numbered sequences with a unique identifier
- Automatic timestamp: every reading carries a date and time from the internal clock
- Waveform storage: on the Dakota CMX and FX instruments the complete A-Scan is saved alongside the numerical value as evidence
- Zero transcription errors: the digital value passes straight from the probe to the instrument to the software
- Fast download to the PC over USB or Bluetooth
- Data integrity: the internal log cannot easily be altered
Storage capacity of the Dakota instruments
| Instrument | Data logger capacity | A-Scan storage |
|---|---|---|
| CX8-DL | 100,000 readings in 1,000 batches | No |
| ZX5-DL / ZX6-DL | 40 files of 250 readings | No |
| MX1-DL / MX2-DL | 4 GB | Yes (with waveform) |
| CMX1-DL / CMX2-DL / CMX3-DL | 4 GB | Yes (with A-Scan) |
| CMX10-DL | 4 GB with full wave capture | Yes (full waveform) |
| PMX2-DL / PMX3-DL | 4 GB | Yes |
| FX70-DL / FX71-DL | 4 GB internal | Yes (A/B-Scan) |
| FX81-DL | 4 GB + SD 64 GB | Yes (A/B-Scan) |
| BT1-DL / BT2-DL | 4 GB | Yes |
Figures verified against the official Dakota NDT datasheets. Every instrument in the “-DL” (Data Logger) family has electronic storage.
Integration with DakMaster™
The internal data logger shows its full value when integrated with the DakMaster™ software. The typical workflow is:
- Measurement campaign with automatic storage in the data logger
- Connection of the instrument to the PC at the end of the campaign (USB or Bluetooth)
- Automatic download of the data into DakMaster™
- Organisation into a project structure (customer, asset, CML)
- Analysis: histograms, statistics, comparison against the baseline
- Generation of professional reports from pre-built templates
- Export to Excel, CSV and PDF for integration with company systems
Regulatory requirements
Many industrial standards explicitly require structured archiving of NDT readings:
- API 570 and API 653: require traceability of readings per CML with the possibility of trend analysis
- ASME PCC-1: requires documentation of the tension of each bolt tightened
- AWS D1.1: requires storage of the A-Scan as evidence of the signal acquired
- EN 4179 / NAS 410 for aerospace NDT: complete traceability
- NADCAP: qualification requirements for NDT data management systems
- ISO 9712: personnel qualification includes the ability to produce structured reports
Return on investment of the data logger
Dakota states that the average NDT inspector spends up to 30 % of the working week producing reports — an official figure given on the DakMaster™ datasheet. Investing in an instrument with a data logger typically pays for itself within a few months thanks to:
- less time spent on reporting
- fewer return visits for missing or incorrect data
- greater acceptance of reports by clients
- the ability to bid for work with demanding reporting requirements
- fewer disputes over contested data
For an assessment of the data logger solution best suited to Your inspection work, contact our technical department.