Folowrd company has produced different models of extensometers. This equipment is used in great scale in different underground projects, building’s foundations and other situations where there is a need for constant monitoring of deformations in different levels of ground. Extensometers anchors types, rod lengths and material are designed according to ground condition of project location. The anchors are borros anchors, packers or groutable. In week ground conditions or loose soils which grouting hasn’t sufficient strength for fixing the anchors, the hydraulic anchors are best alternatives.


  • All kind of ground movements
  • Deformation of different structures foundations
  • Deformation of concrete piles
  • Fracturing in the roofs and walls of underground caverns


Anchors are parts of each rod that are in contact with their sour rending ground by grouting, packering or hooking.


This type of anchors is for using in non-cohesive soils and compact rocks.


Borros type anchors are used for soft soils and clays. Their activation is by hydraulic pressure.

Packer type 

Used in soft soil conditions, granular materials and are used typically in   up-hole installations. inflated with cement by injection tube.


Rods are used to connect the anchors to the reference head and are available in rigid or flexible form.


Made from stainless steel and is available in 1,2, 3…6 meters. Higher lengths are obtained by threaded connection.


The glass & carbon fiber rods are a continuous length factory produced to meet the project requirements


For moving freely, rods need sleeves in place. This is because, one of the installation step, is grouting in grout anchors. The two options are possible:

    • Rigid

Made from rigid PVC or Stainless Steel.

    • Flexible

Made from the flexible nylon.

Reference head

Reference head is apparent part of extensometer while rods are embedded. Heads are available in the following types:


The differences in length can be measured using mechanical measuring tools. and is applicable where there is easy access to the extensometer.


Used when access to the reference head is difficult or where continuous monitoring is required. The sensors are connected to rods in this part. The output signal of measured movement is converted to length by a digital datalogger.


In case of electrical head, Folowrd’s sensors with different ranges can be used. LVDT and linear potentiometers are available for this purpose.  Also mechanical reading without using sensors can be done by using accurate mechanical measuring tools.

    • All sensors are tested and calibrated.
    • All instruments are installed by Folowrd experienced staffs.
Mechanical 0-150mm
LVDT Up to 150mm
Linear potentiometer Up to 150mm
Product Serial FIP-LEEH
Model EXT4000
Electronical LVDT Head characteristic
Sensor type LVDT
Displacement Range 1mm to 150 mm depend on customer order
Channel Points 1 to 5
Typical non-linearity ± 0.1 to ±0.08 depend on Measuring range
Resolution 0.1 … 0.001 mm depend on Measuring range
Total accuracy (linearity+hysteresis+repeatability) <±0.09% FS
Repeatability <0.01% FS
Supply voltage 24 VDC
Storage temperature -55ºC to +90 °C
Operating temperature -40ºC to +125 °C
Logger and Display Compatible with RUD600,RUD400, Readout units
Communication interface RS485
Enclosure IP68
Stainless steel 6 mm 200 GPa 16.0 ppm/C
Fiberglass 5 mm 20 GPa 3.0 ppm/C
Carbon fiber 5 mm 130 GPa <1.0 ppm/C
Length Depend on customer order