7650A High Temperature, Low Strain, Extended Performance Capacitive Extensometers (1200 °C or 1600 °C) Compatible with Materials Testing Furnaces or Induction Heating

The 7650A High Temperature, Low Strain, Extended Performance Capacitive Extensometers are designed to measure axial strains on specimens at temperatures up to 1600 °C (2900 °F). They are compatible with materials testing furnaces or induction heating. They may be used for strain-controlled, high frequency fatigue tests. Slide mounting system enables mounting to hot specimens within a few seconds.

  • With epsilon’s 20+ year history of service, the materials testing community will benefit from the company’s products when their critical application requires it.
  • Epsilon extensometers are designed to match virtually every brand of test equipment and can be provided with the correct connector to plug in directly.
  • All Epsilon’s extensometers are verified to applicable standards such as ASTM E83 or ISO 9513 with the aid of in-house calibration systems that are calibrated using Epsilon’s laser interferometer system.

Model 7650A extensometers measure strains with extremely high precision due to their low strain range and design features. All models can perform tension and compression strain measurement, and can be used for fatigue testing under fully reversed load and strain conditions at frequencies up to 10 Hz.

All of the 7650A models mount rigidly on the load frame and incorporate slide mounting to move the extensometer into contact with the specimen. The gauge length is fixed automatically before mounting on the test specimen, which enables hot mounting after thermal equilibrium has been achieved.

These units are specifically designed to provide high resolution, high accuracy measurements and conduct high temperature fatigue testing at the highest possible frequencies. They consist of capacitive sensors for low operating force and include electronics with programmable filtering and multi-point linearization for enhanced accuracy and performance. The overall design reduces, and in several cases virtually eliminates, any impact from common lab environment vibrations.

These water-cooled extensometers are equipped with high purity alumina rods for specimen contact when testing to 1200 °C (2200 °F). Silicon carbide rods are used for the 1600 °C (2900 °F) high temperature option.

The Model 7650A is regularly customized for specific test requirements.


The main features of the 7650A High Temperature, Low Strain, Extended Performance Capacitive Extensometers are as follows:

  • Hot mountable and retractable
  • Can be left on through specimen failure
  • All models can measure in both compression and tension and may be used for cyclic testing at test frequencies up to 10 Hz
  • Self-setting gauge length with fine adjustment feature
  • Standard units comply with ASTM class B-1 requirements for accuracy. A test certificate is provided. ISO 9513 class 0,5 test certificates can be obtained upon request
  • Ships fully calibrated with calibration that is traceable to NPL; voltage output may be user-specified (typically 0 - 10 V)
  • Superior ambient vibration rejection; primary vibration mode >100 Hz typical
  • Digital controller and power supply are provided. Provides high level DC voltage output with low noise. Easily interfaced to data acquisition boards, test controllers, and chart recorders
  • High speed analog and digital outputs are provided
  • Web-based user interface for setup and data acquisition
  • Selectable digital and analog filter options from 2 Hz to 3 kHz
  • Integrated calibration reference and auto-zero features
  • Several extensometer calibration files can be loaded for use with one controller
  • Can be used with specimens at high temperatures while only needing room temperature calibration
  • Quick-disconnect water cooling fittings and signal cables
  • High quality foam lined case and a spare set of rods are provided


The main specifications of the 7650A High Temperature, Low Strain, Extended Performance Capacitive Extensometers are as follows:

  • Digital output: 24 bit high speed Ethernet output with integrated web interface
  • Analog output: User specified, ±10 VDC typical, ±10.8 VDC rail
  • Cyclic testing: up to 10 Hz, depending on test system and test amplitude
  • Resolution: <75 PPM (0.0075%FS) RMS @ 4 kHz, <6 PPM (0.0006%FS) @ 100 Hz at gauge length
  • Linearity: 11 point digital linearization, ≤0.1% FS typical linearity
  • Hysteresis: ≤0.1% FS typical
  • Filter: Selectable 100 Hz analog and 2 Hz – 3 kHz digital filters
  • Output cables: Flexible 2.4 m (8 ft) analog output cables
  • Sensor cables: 2 m (6.5 ft) room temperature cables
  • Contact force: <560 g typical
  • Operating force: <30 g typical
  • Environment: Recommended for testing in inert/non-corrosive gases, dry air, or vacuum
  • Power: Includes power supply for customer’s country


The options for the 7650A High Temperature, Low Strain, Extended Performance Capacitive Extensometers are as follows:

  • Model 2050 constant temperature water re-circulating bath
  • High temperature option (-HT suffix) for use to 1600 °C
  • Load frame mounting brackets
  • Straight chisel, vee chisel, or conical ceramic rod tips
  • Bulkhead adapters for use in vacuum chambers
  • Connectors to interface to almost any brand test equipment

7650A High Temperature, Low Strain, Extended Performance Capacitive Extensometers (1200°C or 1600°C) Compatible with Materials Testing Furnaces or Induction Heating


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