Diametral Extensometers for Rock and Concrete Testing – Model 3975

Designed for accurate measurement of small diametral strains such as those required to determine Poisson’s ratio of rock, concrete and asphalt samples. The units are designed to be used in conjunction with the Model 3542RA axial averaging extensometer.
diametral strain measurement rock and concrete Epsilon Technology Model 3975

Epsilon extensometers are COMPATIBLE WITH VIRTUALLY EVERY BRAND OF TEST EQUIPMENT and can be supplied with the correct connector to plug in directly, or supplied with a separate conditioner and amplifier.

WITH EPSILON’S 20+ YEAR HISTORY OF SERVICE to the materials testing community, you know we will be there to stand behind our products when your critical application requires it.

36 EXTENSOMETER MODELS are available in many thousands of variations. Our focus on helping customers has led to the development of models to cover nearly any test method.

Self-supporting on the test sample, these extensometers will work on standard sized diameter samples, but special configurations are available upon request. They are designed for use in testing for Poisson’s ratio and for applications where accurate diametral measurements with low strains are required.

The Model 3975 is the best choice for small diametral strains in large compression samples. Epsilon’s circumferential extensometer, Model 3544, is recommended for large strain measurements. These units are easily attached to the sample, and rounded contact edges maintain the position on the specimen.

The Model 3975 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 with electronics for a strain channel, and Epsilon will equip the extensometer with a compatible connector that is wired to plug directly into the controller. For systems lacking the required electronics, Epsilon can provide a variety of signal conditioning solutions that enable connecting to data acquisition systems or other equipment.

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  • Full bridge, 350 ohm strain gaged design for compatibility with nearly any test system.
  • All standard units have linearity readings of 0.20% or better.
  • Easy mounting, attaches with integral springs.
  • Self-supporting on the specimen.
  • Includes the Epsilon Shunt Calibration System for on-site electrical calibration.
  • Rugged, dual flexure design for improved performance.
  • Includes high quality foam lined case.

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

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

Linearity: ≤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)

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



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  • Additional frames for larger or smaller diameter samples
  • Connectors to interface to nearly any brand of test equipment

Download Data Sheet


Ordering Information

Click table options to configure

Measuring Range i
extension #
+0.76 mm -076M 076M
+1.50 mm -150M 150M
+2.00 mm -200M 200M
+0.030 in -0003 0003
+0.060 in -0006 0006
+0.080 in -0008 0008
Temperature Range
degrees #
-270 °C to 100 °C (-454 °F to 210 °F) -LT LT
-40 °C to 100 °C (-40 °F to 210 °F) -ST ST
-40 °C to 150 °C (-40 °F to 300 °F) -HT1 HT1
-40 °C to 200 °C (-40 °F to 400 °F) -HT2 HT2
-270 °C to 200 °C (-454 °F to 400 °F) -LHT LHT
Model Number:  3975 _ _ _ __ _ _ _
Model Number:
3975 _ _ _ __ _ _ _
Model 3975 Available Versions: Consult factory for additional ranges. Other configurations may be available with special order; please contact Epsilon to discuss your requirements.
Example: 3975-0008-ST: +0.080 inches measuring range, standard temperature range (-40 °F to 210 °F)


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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