7641 High Temperature Clip-On Gages (600 °C) for Fracture Mechanics Testing in Environmental Chambers

The 7641 High Temperature Clip-On Gages are designed for fracture mechanics testing in environmental chambers where the entire gage must be exposed to high temperatures. These capacitive sensors can be used up to 700 °C (1300 °F) without requiring any cooling.

The Model 7641 provides a number of improvements to Epsilon’s offerings for an uncooled, axial extensometer including:

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

Epsilon extensometers are compatible with almost every brand of test equipment and can be delivered with the correct connector to plug in directly.

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.

These COD gages 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 7641 is suitable for the determination of fracture mechanics parameters such as KIC, JIC, R-curve, fatigue crack growth rate (da/dN), and testing to standards such as E399, E1820, E647, etc. All units can be displaced slightly in compression for easy installation.

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

The 7641 can be easily interfaced with a number of current test controllers and may be directly connected to a chart recorder or data acquisition system, or directly to a PC. The 7641 can be used for strain controlled tests such as JIC.


The key features of the Model 7641 are listed below:

  • Can be left on through specimen failure
  • Improved performance at high temperature
  • Improved noise rejection, accuracy, and resolution
  • Improved clearance with a number of clevis designs
  • Improved linearity and reduced stiffness
  • Reduced weight and size, and better high frequency performance
  • All standard models are ideal for cyclic testing
    • >25 Hz is typical for 10 mm GL and larger, up to 100 Hz for some configurations
    • Typically limited by the user’s test apparatus, filter selection, and software settings
  • Digital controller and power supply are included. Provides high level DC voltage output with low noise. Can be easily interfaced to test controllers, chart recorders, and data acquisition boards
    • High speed analog and digital outputs are included
    • Intuitive web-based user interface for setup, calibration, and data acquisition
    • Integrated calibration reference and auto-zero features
    • Multiple extensometer calibration files can be loaded for use with a single controller
    • Multiple temperature-specific calibrations can be stored
    • Selectable digital and analog filter options from 2 Hz to 3 kHz
  • Delivered fully calibrated with electronics (traceable to NPL (UK)) with user specified voltage output.
  • Mechanical over-travel protection
  • All standard units comply with current ASTM E399, ASTM E1820 and ISO 12135 requirements for accuracy
  • Durable stainless steel knife edges
  • High quality foam lined case is provided
  • Rugged, dual flexure design for strength and enhanced performance. The next-generation design enables cyclic testing at much higher frequencies


The key specifications of the Model 7641 are provided below:

  • Analog output: User specified, +/-5 VDC or +/-10 VDC typical, ±10.8 VDC rail
  • Digital output: 24 bit high speed Ethernet output with built-in web interface
  • Analog filter: Selectable 100 Hz analog and 2 Hz - 3 kHz digital filters
  • Linearity: 11 point linearization, ≤0.1% FS typical linearity
  • Cyclic testing: >25 Hz typical @ 10 mm GL, >10 Hz @ 5 mm GL
  • Resolution: <55 PPM (0.006%FS) RMS @ 4 kHz, <6 PPM (0.0006%FS) @ 100 Hz
  • Temperature sensitivity (Gain): Temperature sensitivity (Offset): 20 PPM / °C (0.002%FS / °C) typical
  • Temperature range: Ambient to 700 °C (1300 °F). Use up to 800 °C is possible - contact Epsilon for details. Springs may require periodic adjustment or replacement after long-term testing above ~600 °C
  • Operating force: 1 - 5 kg typical, depending on model
  • Sensor cable: 0.7 m (2.5 ft) tri-axial high temperature cable, plus 1.5 m (5 ft) room temperature extension cable
  • Environment: Recommended for high temperature testing in dry air or inert/non-corrosive gases
  • Power: Includes power supply applicable to customer’s country


The following options are offered with the Model 7641:

  • Bulkhead adapters for vacuum chambers
  • Connectors to interface to nearly any brand test equipment
  • Dual-channel DT6229 controller is provided
  • Bolt on knife edges for attachment to test specimens without machined attachment points
COD gage for high-temperature fracture mechanics and fatigue crack growth testing up to 700 °C

7641 High Temperature Clip-On Gages (600°C) for Fracture Mechanics Testing in Environmental Chambers


Other Equipment by this Supplier

While we only use edited and approved content for Azthena answers, it may on occasions provide incorrect responses. Please confirm any data provided with the related suppliers or authors. We do not provide medical advice, if you search for medical information you must always consult a medical professional before acting on any information provided.

Your questions, but not your email details will be shared with OpenAI and retained for 30 days in accordance with their privacy principles.

Please do not ask questions that use sensitive or confidential information.

Read the full Terms & Conditions.