The EN3 tape extensometer, EN3 allows the measurement of the relative movements between two points distant from each other (2m


The instrument is generally used for convergence measurement in galleries and for distance variations in:

  • Galleries
  • Excavations
  • Retaining walls
  • Diaphragms
  • Bridges
  • Jetties and wharves
  • Rockslides
  • Caves
  • Other

Features and Benefits

  • Robust
  • Precise
  • Easy to apply
  • Easy to use
  • Attachable to ring fixtures
  • Available in hooking version joint for fixtures with a threaded head
  • Can be used on frames with the possibility of interchange with topographical targets

Measurement Principle

The instrument is composed of a measuring body with centesimal comparator, a dynamometer system and a steel centimetered tape perforated at regular intervals. The free end of the perforated tape coming out of the instrument, and the body of the instrument are equipped with connections which are hooked to the fixtures cemented in the structure to be monitored during the measurement phase.
During the measurement phase, a locking pin allows the tape to be integrated with the body of the instrument; the tape is generally engaged in the nearest hole to the base to be measured. A knurled drum, placed on the instrument allows the tape to be tensioned, enabling correct measurement.
For the realization of the reference points we offer standard fixtures consisting of steel bars with a coupling ring on the head, or fixtures with a simple thread and cover. The latter fixtures are generally used also for application of prisms or topographic targets.

Technical Specifications

Length of the tape 20m; 30m
Dial Gauge


Optional: digital

Range of the dial gauge 30mm
Accuracy of the dial gauge 0,01mm
Repeatability of the measurement at constant temperature 0,1mm
Standard Hooks Carabiner
Optional: with threaded joint
Material Plated brass, stainless steel ; internal parts in anodized aluminium
Housing 80 x 20 x 15 cm
Weight of the instrument with Housing 6,5 Kg

Accessories and related products

Ring Fixture To be applied on the wall
Joint Fixture To be applied on the wall
Pair of carabiner hooking To be applied on the steel tape
Pair of screw hooks with joint To be applied on the steel tape
Stainless steel tape L=20 m, perforated As spare part
Stainless steel tape L=30 m, perforated As spare part
Collimation Aim for the screw fixture
Optical Prism for screw fixture

Technical Assistance

If you have any requests or questions about our instruments or if you have special needs that require different solutions from the standard, please contact us. Our team will provide all the necessary information and will be very happy to work with you to study, develop and customize instruments and solutions suitable for your specific needs.
All information in our datasheet is subject to change without prior notice.
Please check the datasheet/details carefully and contact Pizzi Instruments for further information