Description
Model: EDS-91
The EDS-91 Magnetic Extensometer is designed to measure vertical and horizontal ground movement, such as settlement or heave in foundations, embankments, fills, and excavations. This instrument offers a robust, lightweight, and highly accurate solution for geotechnical monitoring applications.
The system operates on a magnetic detection principle and includes an access tube, magnet assemblies, and a portable magnetic probe with a reed switch. During operation, the probe is lowered inside the access tube—previously installed with magnet assemblies at specific depths—to detect the displacement of each magnet caused by vertical or lateral ground movement.
A variant of the system is also available for monitoring horizontal displacement in embankments, incorporating a pull-cable reel and dead-end pulley arrangement. Magnet assemblies are also compatible with standard inclinometer casings, enhancing system versatility.
Different magnet types are available to suit varying site conditions:
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Datum magnet: establishes the reference position.
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Spider magnet (6-leaf): ideal for grouted boreholes.
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Spider magnet (3-leaf): suitable for boreholes and can be pushed into position using a rod.
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Plate magnet: used in fills and embankment monitoring.
Specifications
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Instrument type: Magnetic Extensometer
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Sensor type: Mechanical (reed switch magnetic detection)
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Configuration: Plate and spider magnet assemblies with magnetic probe for manual readings
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Application: Monitoring vertical and horizontal ground movement in boreholes, fills, and embankments
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Measured parameter: Settlement / heave
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Measuring range: 30, 50, 100, 150, 200, 300 m or 50, 100, 150, 300, 500 ft (depending on probe)
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Testing & calibration: Measurement accuracy verified through standard calibration procedure
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Key features:
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Suitable for both vertical and horizontal installations
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Compatible with inclinometer casings
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Lightweight, durable, and field-portable
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Provides reliable readings over long monitoring periods
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