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Miniature Averaging Axial Extensometers – Model 3442RA1

With gauge lengths of 1 and 2 inches (25 and 50 mm) and measuring ranges of 0.050 and 0.100 inches (1.2 and 2.5 mm), the Model 3442RA1 was designed for applications where tensile or compressive strength tests on small rock, concrete and other small compression samples is desired.

Gauge Lengths:

25 – 50 mm

Measuring Ranges:

±1.25 mm and ±2.5 mm

Temperature Range:

-265 °C to 200 °C with -LHT option

Key Features:

Miniature averaging axial rock/concrete extensometer

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Axial strain is measured on opposite sides of the test specimen and the output is an average of the two readings. The Model 3442RA1 is available in a variety of configurations for samples 50 mm (2 inches) or smaller in diameter. All are self-supporting on the specimen and mount very easily. The conical point contacts included with the extensometer are made from tungsten carbide. If desired, the two cut-outs can be independently configured, providing two readings. Epsilon has versions for use in oil to 1360 bar at 200 °C (20,000 psi at 400 °F). These units will fit in small inside diameter vessels. For large diameter specimens, we suggest one of the Model 3542RA averaging axial extensometers. The Model 3442RA1 extensometers are strain gaged devices, making them compatible with any electronics designed for strain gaged transducers. Most often they are connected to a test machine controller. The signal conditioning electronics for the extensometer is typically included with the test machine controller or may often be added. In this case the extensometer is shipped with the proper connector and wiring to plug directly into the electronics. For systems lacking the required electronics, Epsilon can provide a variety of solutions, allowing the extensometer output to be connected to data acquisition boards, chart recorders or other equipment.
  • Full bridge, 350 ohm strain gaged design for compatibility with nearly any test system.
  • High accuracy, averaging output or optional dual independent outputs.
  • 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.
  • Rugged, dual flexure design for strength and improved performance.
  • Includes high quality foam lined case.
  • Easy mounting, attaches with integral springs.
  • Self-supporting on the specimen.
  • Designed for smaller diameter specimens.


5 to 10 VDC recommended, 12 VDC or VAC max.


2 to 4 mV/V, nominal, depending on model


≤0.20% of full scale measuring range, depending on model

Temperature Range:

Standard (-ST) is -40 °C to +100 °C (-40 °F to 210 °F)


Integral, ultra-flexible cable, 2.5 m (8 ft) standard

Operating Force:

<30 g typical per side
  • Dual, independent outputs
  • Connectors to interface to nearly any brand test equipment
  • Shunt Calibration
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