7642 High Temperature Un-Cooled Axial Extensometers (700 °C), Ideal for Testing Composites, Metals and High Temperatures

The Model 7642 is designed for use in environmental chambers where the entire extensometer must be exposed to high temperatures. These capacitive extensometers can be used up to 700 °C (1300 °F) without any cooling.

The 7642 extensometers use a high-temperature capacitive sensor. They will operate up to the maximum temperature limit of most environmental chambers that are used in materials testing. The Model 7642 is suitable for testing metals, composites, and high temperature polymers in compression, tensile or cyclic testing. All units can be displaced in both tension and compression.

The extensometer comes with the advanced DT6229 controller. The standard output is 0 - 10 VDC analog signal, factory calibrated with the extensometer. This system provides several functional enhancements, including built in calibration and tare functions, high speed digital output, analog and digital filters and more.

These 7642 is readily interfaced with most existing test controllers, and can be directly connected to a chart recorder, or data acquisition, or directly to a PC. The 7642 may be used for strain controlled tests such as low cycle fatigue (LCF).

The Model 7642 has many improvements to Epsilon’s offerings for an uncooled, axial extensometer including:

  • A new probe design provides several improvements including better frequency response, lower noise, durability, and improved flexibility
  • Increased operational temperature
  • A new body style to reduce weight and size, and to optimize mechanical performance
  • The ability to store calibrations of many extensometers with one signal conditioner

Epsilon’s extensometers are designed for very high accuracy and have performance that is significantly better than required by many testing standards and conforming to the highest requirements of ISO 9513 and ASTM E83. The company has 20+ years history of service for the materials testing community, and will be there to stand behind their products when the user’s critical application requires it.


The key features of the Model 7642 are as follows:

  • Reduced weight and size, and improved high frequency performance up to 100 Hz
  • Enhanced performance at high temperature
  • Can be left on through specimen failure
  • Mechanical over-travel stops
  • Includes a high quality foam lined case and a spare set of knife edges
  • Improved noise rejection
  • All models can measure in both compression and tension, and can be used for cyclic testing
  • Hardened tool steel knife edges can be easily replaced. A spare set comes with every extensometer
  • Includes power supply and digital controller. Provides high level DC voltage output with low noise. Can be easily interfaced to data acquisition boards, test controllers, and chart recorders
    • Built-in calibration reference and auto-zero features
    • Selectable analog and digital filter options from 2 Hz to 3 kHz
    • Includes high speed analog and digital outputs
    • Many extensometer calibration files can be loaded for use with one controller
    • Intuitive web-based user interface for setup, calibration, and data acquisition
    • Multiple temperature-specific calibrations can be stored
  • Rugged, dual flexure design for improved performance and strength. Much stronger than single flexure designs, and this also allows cyclic testing at higher frequencies
  • Ships fully calibrated with electronics with user specified voltage output (traceable to NPL)
  • Standard units comply with ASTM class B-1 requirements for accuracy. A test certificate is provided. ISO 9513 class 0,5 test certificates are available upon request


The key specifications of the Model 7642 are as follows:

  • Linearity: 11 point linearization, ≤0.1% FS typical linearity
  • Analog output: User specified, ±5 VDC or ±10 VDC typical, ±10.8 VDC rail
  • Analog filter: Selectable 100 Hz analog and 2 Hz – 3 kHz digital filters
  • Resolution: <55 PPM (0.006%FS) RMS @ 4 kHz, <6 PPM (0.0006%FS) @ 100 Hz
  • Sensor cable: 0.7 m (2.5 ft) tri-axial high temperature cable, plus 1.5 m (5 ft) room temperature extension cable
  • Standard quick attach kit: Fits round samples up to ∅15 mm (0.60"). Fits flat samples up to 50 mm (2.0") wide with thicknesses up to 6.35 mm (0.25"), and up to 19 mm (0.75") wide with thicknesses from 6.35 mm (0.25") to 12.5 mm (0.50").
  • Cyclic testing: >25 Hz typical, up to 100 Hz with small travel units, @ 0.5 mm p-p
  • Temperature Sensitivity (Gain): <100 PPM / °C (0.01%FS/°C) typical
  • Digital output: 24 bit high speed Ethernet output with built-in web interface
  • Power: Includes power supply for user’s country (specify)
  • Temperature sensitivity (Offset): 20 PPM / °C (0.002%FS / °C) typical
  • Operating force: <100 g typical
  • Temperature range: Ambient to 700 °C (1300 °F). Use up to 800 °C is possible - contact Epsilon for details. Wire forms may require periodic adjustment or replacement after long-term testing above ~600 °C.
  • Environment: Recommended for elevated temperature testing in dry air or inert/non-corrosive gases


The following options are offered with the Model 7642 extensometers:

  • Connectors to interface to virtually any brand test equipment
  • Dual-channel DT6229 controller available
  • Gauge length adapter kits (for use at temperatures ≤ 300 °C (570 °F))
  • Bulkhead adapters for vacuum chambers

7642 High Temperature Un-Cooled Axial Extensometers (700°C), Ideal for Testing Composites, Metals and High Temperatures


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