Choosing the Right Transducer

This table presents a number of advanced transducer and control options that are available to determine soil properties typically unobtainable with conventional systems, or soil response that is more closely representative of in-situ soil conditions.

TransducerMain Function
RangeSoil / Rock
Hall Effects Transducers
Greater accuracy strain can be measured by using local strain transducers.
  • 1.7MPa
  • +/- 3mm

LVDT Transducers
GDS’ LVDT transducers are available in two types, low pressure and high pressure, they mount directly onto the specimens membrane to record on-sample small strain measurements of axial and radial strain.
  • Triaxial Systems (range from 50mm+ diameter specimens) (requires access ring)
  • EMDCSS (used for vertical measurement and direct pedestal to topcap measurement)
  • Up to 3.5MPa       +/-2.5mm,         +/-5mm,           +/- 10mm
  • Up to 100MPa     +/- 2.5mm         +/- 5mm
Low pressure (Soil)

High pressure
Mid Plane Pore Pressure Transducer
To increase the accuracy of pore pressure measurement during consolidation and shear, mid-plane pore pressure transducers can be fitted within a triaxial system.
  • 1500kPa
Bender Elements System
The very small strain response of a soil specimen can be determined through bender element testing.
  • 50mm+ diameter specimens
  • Up to 3.5MPa

Wet Wet Differential Transducer
GDS offers two types of Wet Wet transducer. One is used with the HKUST UNSAT method to measure volume change by means of hydrostatic head pressure changes. The other is to measure the back-base pressure differential for permeability testing.
  • Up to +/- 1.5kPa (HKUST version)
  • 200 or 50kPa range (differential pressure transducer for permeability)
Soil / Rock
Internal Submersible Load Cells
Designed to be submersible, the confining pressure does not affect the load readings recorded by the transducer. This in-turn removes friction of the ram and the up-thrust created from the test recordings, creating more accurate results. 
  • Load Cells up to 100MPa with
  • Loads up to 1500kN
Soil / Rock
Linear Strain Displacement Transducers
GDS’ Linear Displacement Transducers are the next new generation of strain gauge type transducers. Used in a wide variety of industries and applications, the linear displacement transducers are precision engineered with a robust construction.
All GDS Systems
  • 0 - 10mm
  • 0 - 25mm
  • 0 - 50mm
  • 0 - 100mm
Soil / Rock
Pore Pressure Transducers
Pore Pressure Transducers are used to measure pressure during testing.  Typically used for pore pressure measurement, the transducers can be combined with remote feedback modules to provide additional reading for cell/back or lower chamber pressure.
All GDS Systems
  • Up to 100MPa

The S-Beam Load Cells are designed to measure load during testing. Non-submersible, these load cells are situated outside of the triaxial cell, between the top of the ram and the reaction bar of the load frame, or attached to a force actuator.
Up to 100kN
Soil/Soft Rock
Acoustic Velocity Transducer
Acoustic Velocity (AV) sensors are generally used where pressures and load exceed those where bender elements can be used. AV sensors are based on the same principle as bender elements however, the piezo ceramic elements are not exposed to the environment so they can be used at pressures up to 100MPa and loads up to 2MN.
  • GDS Triaxial Cells (typically high pressure)
Up to 100MPa 
Up to 2MN