High Temperature, Low Strain, Extended Performance Capacitive Extensometers

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

    All 7650A models mount rigidly on the load frame and incorporate slide mounting to bring the extensometer into contact with the specimen. The gauge length is set automatically before mounting on the test specimen, which allows for hot mounting after thermal equilibrium has been reached.

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

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

    The Model 7650A is often customized for specific test needs. Contact Epsilon for a configuration that matches your requirement.



  • • May be left on through specimen failure.

    • Hot mountable and retractable.

    • Self-setting gauge length with fine adjustment feature.

    • All models can measure in both tension and compression and may be used for cyclic testing at test frequencies up to 10 Hz.

    • Standard units meet ASTM class B-1 requirements for accuracy. A test certificate is included. ISO 9513 class 0,5 test certificates are available upon request.

    • Ships fully calibrated with calibration that is traceable to NPL; voltage output may be user-specified (typically 0-10V).

    • Excellent ambient vibration rejection; primary vibration mode >100 Hz typical.

    • 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.

    • Web-based user interface for setup and data acquisition.

    • Selectable analog and digital filter options from 2 Hz to 3 kHz.

    • Built-in calibration reference and auto-zero features.

    • Multiple extensometer calibration files may be loaded for use with one controller.

    • Can be used with specimens at elevated temperatures while only requiring room temperature calibration.

    • Quick-disconnect water cooling fittings and signal cables.

    • Includes high quality foam lined case and a spare set of rods. 



  • High temperature option (-HT suffix) for use to 1600℃ 

    Load frame mounting brackets

    Bulkhead adapters for use in vacuum chambers

    Model 2050 constant temperature water re-circulating bath

    Connectors to interface to nearly any brand test equipment

    Specify rod tip style desired. Available choices: straight chisel, vee chisel, or conical 



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

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

    Cyclic Testing: up to 10 Hz, depending on test system and test amplitude

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

    Hysteresis: ≤0.1% FS typical

    Resolution: <75 PPM (0.0075%FS) RMS @ 4 kHz, < 6PPM (0.0006%FS) @ 100 Hz at gauge length

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

    Temperature Range: Standard (-ST) is to 1200℃ (2200°F), optional (-HT) 1600℃ (2900°F)

    Sensor Cables: 2 m (6.5 ft) room temperature cables

    Output Cables: Flexible 2.4 m (8 ft) analog output cables

    Operating Force: <30 grams typical

    Contact Force: <560 grams typical

    Environment: Recommended for testing in dry air, inert / non-corrosive gases, or vacuum

    Power: Includes power supply for your country 


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High precision extensometer measures axial strains on specimens at temperatures up to 1600℃ (2900°F). Compatible with materials testing furnaces or induction heating. May be used for strain-controlled, high frequency fatigue tests. Slide mounting system enables mounting to hot specimens in seconds.
Gauge Lengths:
12.5-25 mm
Measuring Ranges:
+2.5 mm / -0.5 mm typical
Temperature Range:
Ambient to 1600℃ with -HT option
Key Features:
Hot-mountable, extended performance furnace extensometer