High Temperature Un-Cooled Extensometers (700 °C) – Model 7642

For use in environmental chambers where the entire extensometer must be exposed to elevated temperatures. These capacitive extensometers may be used up to 700 °C (1300 °F) without any cooling.
The Model 7642 INTRODUCES SEVERAL IMPROVEMENTS to Epsilon’s offerings for an uncooled, axial extensometer including:

  • A new body style to optimize mechanical performance and reduce weight and size
  • A new probe design that also provides many improvements including lower noise, better frequency response, improved flexibility and durability
  • Increased operational temperature
  • The ability to store calibrations of multiple extensometers with one signal conditioner
Epsilon’s extensometers are DESIGNED FOR VERY HIGH ACCURACY, with performance significantly better than required by many testing standards and conforming to the highest requirements of ASTM E83 and ISO 9513.


to the materials testing community, you know we will be there to stand behind our products when your critical application requires it.

These extensometers use a high-temperature capacitive sensor and do not require any cooling. They will operate up to the maximum temperature limit of most environmental chambers used in materials testing. The Model 7642 is ideal for testing composites, metals and high temperature polymers in tensile, compression or cyclic testing. All units can be displaced in both compression and tension.

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

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

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

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Analog Output: User specified, ±5 VDC or ±10VDC typical, ±10.8VDC rail

Digital Output: 24 bit high speed Ethernet output with built-in web interface

Accuracy: Standard configurations meet ASTM E83 class B-1 and ISO 9513 class 0,5 requirements for accuracy. A test certificate is included.

Linearity: 11 point linearization, ≤0.1% FS typical linearity

Resolution: <55 PPM (0.006%FS) RMS @ 4 kHz, <6 PPM (0.0006%FS) @ 100 Hz

Cyclic Testing: >25 Hz typical, up to 100 Hz with small travel units, @ 0.5 mm p-p

Analog Filter: Selectable 100 Hz analog and 2 Hz – 3 kHz digital filters

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.

Temperature Sensitivity (Gain): <100 PPM / °C (0.01%FS/°C) typical (see Temperature Sensitivity Compensation)

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 Ø15 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″).

Operating Force: <100 g typical

Environment: Recommended for elevated temperature testing in dry air or inert / non-corrosive gases

Overall Dimensions: Contact Epsilon for overall dimensions

Power: Includes power supply for your country (specify)




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

Download Data Sheet

Ordering Information

Click table options to configure

Gauge Length i
mm or inches #
10.0 mm -010M 010M
12.0 mm -012M 012M
12.5 mm -0125M 0125M
20.0 mm -020M 020M
25.0 mm -025M 025M
50.0 mm -050M 050M
0.50 in -0050 0050
1.000 in -0100 0100
2.000 in -0200 0200
Measuring Range i
extension #
+2.5/-0.5 mm * -025M 025M
+7.5/-0.5 mm ** -075M 075M
+12.5/-0.5 mm ** -125M 125M
+0.10″/-0.02″ * -010T 010T
+0.30″/-0.02″ ** -030T 030T
+0.50″/-0.02″ ** -050T 050T

Model Number:  7642_ _ _ __ _ _ _

Selected Tensile Measuring Range: _ _ _ _

Model 7642 Available Versions: ANY combination of gauge length and measuring listed above is available, except as noted. Other configurations may be available with special order; please contact Epsilon to discuss your requirements.

*tilted cable exit
**vertical cable exit; contact Epsilon for larger compression ranges

Example: 7642-025M-075M: 25.0 mm gauge length, +7.5/-0.5 mm measuring range


If your unit is in need of service, calibration or repair, initiate the RMA process with us and we will be happy to assist.

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