Digital Tape Extensometer
The CONVEX-D digital tape extensometer measures the relative change in distance between two fixed reference points, using a punched steel survey tape with a digital display for precise readings.
- Range
- 20 m, 30 m, 66 ft or 100 ft
- Resolution
- 0.01 mm (LCD indicator)
- Repeatability
- ±0.10 mm
Overview
In detail
How it works
A steel survey tape with punched holes is loaded on a reel; a pivoting latch locks the tape in position and a digital indicator reads the relative change between two reference points, viewed through the rotary protection drum. An anti-backlash tensioning mechanism keeps accuracy consistent over time, and two superimposed magnifying lenses optimise visual alignment when the tape is tensioned to a fixed 133.5 N (30 lbf) load by rotating a knurled collar.
A verification frame can be used to regularly check the instrument's repeatability.
Installation
The tape is stretched between two stainless steel eyebolts, each fixed to an anchor chosen for site conditions - rebar grouted into boreholes, expansion shell anchors, or eyebolts bolted or welded directly to structural steel. To take a reading, the tape's snap hook is fixed to one reference point, the tape is unwound to the opposite anchor, slack is taken up on the reel, and the locking pin is inserted into the nearest tape hole before tensioning to the reference alignment.
Reach out and say hi
Specifications
Technical specifications
- Range
- 20 m, 30 m, 66 ft or 100 ft
- Resolution
- 0.01 mm (LCD indicator)
- Repeatability
- ±0.10 mm
- Operating temperature
- 0°C to 40°C
- Eyebolt
- Stainless steel with two nuts, 6.35 mm diameter x 50 mm length
- Anchor (Type A)
- 20 mm diameter x 150 mm length, grouted in borehole
- Anchor (Type B)
- 13 mm drilled hole x 35 mm depth, expansion shell
Downloads
Documentation, openly available
Everything you need to specify, install and integrate the Digital Tape Extensometer — no login, no paywall.
Related
Often specified alongside
ESS Earth
Resistance Wire Extensometer RWE
- Application
- Underground hard rock and coal mine displacement monitoring
- Monitoring points
- Pillars, stope walls, roof
Geosystems
JM Series Vibrating Wire Jointmeter
- Range
- 25, 50, 100, 150, 200, 250, 300 mm (200/250/300 mm not available for JM-E)
- Accuracy
Ready to specify?
Add Digital Tape Extensometer to your enquiry
Build a list, add your site notes, and an ESS engineer will quote the lot — cables, mounting and calibration included.
