Magnetic Extensometer

Model EDS-91 Overview

The EDS-91 measures settlement or heave in foundations, embankments, fills, excavations etc. This magnetic settlement recorder is accurate, robust, light weight and convenient to use.

The system consists of an access tube, magnet assemblies and a portable magnetic probe with a reed switch. The probe is inserted inside the access tube installed with magnet assemblies at various depths, to detect the change in position of the magnet assemblies due to vertical soil movement. Magnet assemblies suitable for the inclinometer casing are also available. A similar system for monitoring horizontal displacement in embankments is available with a pull cable reel and dead end pulley assembly.

  • Datum magnet: for reference
  • Spider magnet with 6 leaves: for boreholes
  • Spider magnet with 3 leaves: for boreholes; can also be pushed in by a rod.
  • Plate magnet: for fills & embankments.


Range (m)30, 50, 100, 150, 200, 300
Resolution1 mm
Probe dimension22 mm Φ, 150 mm long
Access tubePVC, 25.5 mm i.d., 32.5 mm o.d., 3 m long, fitted at both ends, with telescopic couplings having dimensions 35 mm i.d., 41.5 mm o.d., length 1 m, 2 m, 3 m
Range (ft)50, 100, 150, 300, 500
Resolution0.1″ standard