Geokon · tiltmeter

Geokon Model 6150 Digital Tiltmeter

The Geokon Model 6150 is a uniaxial / biaxial digital tiltmeter used for high-precision continuous monitoring of structural rotation. The instrument employs a MEMS-based inclinometer and outputs digital data via RS-485 / Modbus protocol, supporting multi-instrument daisy-chained monitoring arrays. Stated resolution is approximately 1 arc-second (4.8 µrad) with operational range of ±15° (standard) or ±90° (wide-range variant). The 6150 is mounted via stainless-steel base plate to vertical or horizontal surfaces and measures tilt change against the initial installation reading. Typical applications include heritage masonry wall-tilt monitoring, retaining-wall movement, post-tensioned slab deflection, and post-disaster building stability monitoring.

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TRSC Application Commentary

TRSC specifies the Geokon 6150 on every condition-monitoring engagement that requires arc-second resolution structural rotation data. The instrument is the workhorse of TRSC's monitoring system designs because it is robust, calibrated stable over years, and integrates into automated data-logging systems via standard Modbus protocol. Two operational notes from extensive field use: first, the installation is critical — the base plate must be mounted to sound substrate (not loose render or coating), with structural adhesive (typically epoxy) fully cured before the initial reading. A poorly-bonded base plate produces drift that masquerades as structural movement. Second, thermal expansion of the substrate produces apparent tilt that must be filtered from the structural signal — TRSC includes ambient-temperature logging at every tiltmeter installation to support thermal compensation in the data-analysis stage. The 6150 was deployed on the Prince Consort Hotel boundary wall to confirm post-remediation stability following Heli-Fix tie installation, and is the standard instrument TRSC specifies for post-remediation monitoring of heritage masonry walls. Data telemetry is via Geokon GeoNet wireless logger or wired CR1000-series Campbell data logger; data review is integrated into TRSC's standard quarterly monitoring report cycle. The 6150 is also TRSC's preferred instrument on temporary works monitoring engagements (façade-restraint scaffolds, propping systems, retaining-wall construction-phase tilts) where the high resolution and short-term stability are the deciding factors over the longer-term life of a permanent installation, and the cabled Modbus wiring is straightforward to set up and remove within a single construction phase.

Enabled Investigations
  • Heritage masonry wall-tilt monitoring
  • Post-remediation stability monitoring
  • Retaining-wall movement monitoring
  • Post-disaster building tilt monitoring
Frequently Asked Questions

Application questions about Geokon Model 6150 Digital Tiltmeter

How precise is the Geokon 6150 in real-world field use?
Stated resolution is ~1 arc-second (4.8 µrad). Real-world precision after thermal compensation and substrate-bond settling is typically 5-10 arc-seconds, which is more than sufficient to detect structural rotation of engineering concern. TRSC's analysis methodology includes 14-day thermal calibration windows and substrate-bond stabilisation before reporting any structural movement signal.
How long does a tiltmeter monitoring deployment typically run?
TRSC monitoring deployments range from 6 months (post-remediation verification) to multi-year (long-term heritage asset condition monitoring). The 6150 is calibrated stable over years; the limiting factor on long-term deployments is typically logger power supply and telemetry maintenance rather than the tiltmeter itself.
Can a tiltmeter detect crack movement?
Indirectly. A tiltmeter installed across a crack will detect rotation associated with crack opening or closing, but the conversion from rotation to crack-width depends on the geometry. For direct crack-width measurement TRSC pairs the 6150 with a Geokon 4000 vibrating-wire crack meter, which gives a direct mm-scale displacement reading across the crack.
Relevant Services
Condition Assessment
Remediation Design
Heritage Structural Engineering
Sources & Further Reading