....Model 3448 High
    Temperature Extensometer ....

Model 3448 with 0.5 in. gage length
Designed for use with furnaces and induction heating systems, these extensometers use Epsilon’s exclusive self-supporting design. A wide range of options cover most testing.

Epsilon has developed a very unique high temperature extensometer for testing metals, ceramics and composites at the high temperatures produced by furnaces and induction heating systems. A combination of new features make these extensometers easier to use and better in performance than other high temperature extensometers.

The units are held on the specimen by light, flexible ceramic fiber cords. These make the extensometer self-supporting on the specimen. No furnace mounting brackets are required. The side load on the test sample is mostly eliminated because of the self supporting design and light weight of the sensor. Most materials testing furnaces with a side cut-out for an extensometer will readily accept a model 3448. For induction heating systems, a different ceramic cord placement allows the extensometer to easily pass between the coils.

The combination of radiant heat shields and convection cooling fins allow this model to be used at specimen temperatures up to 1200 C (2200 F) without any cooling. An optional tiny air fan does enhance stability at the highest temperatures and is recommended for the highest accuracy and for tests with small elongations. The fan comes with a magnetic base for support so it can be mounted at any convenient location near the extensometer. Fan cooling is not generally needed for induction heated systems.

High purity alumina (min 99.7%) ceramic rods are used. These are available in lengths as required to fit your furnace. A spare set is included with every extensometer. Specify chisel, vee chisel or conical contact points as desired.

All units operate equally in tension and compression. Thus tensile, compression and cyclic tests like low cycle fatigue can all be done with a single unit.

For vacuum furnaces, water cooled versions are available. Epsilon also can provide a radiant heat transfer cooled version. This requires that the extensometer module be surrounded by a water cooled enclosure with a front slot for the ceramic rods. Contact Epsilon for details.


Lightweight, but rugged, the self supporting design greatly reduces specimen side loading. Most models weigh only 25 to 35 grams.
Mount with flexible ceramic fiber cords. Very simple to install, this Epsilon exclusive design is much easier to use compared to extensometers which require furnace brackets. Low contact force does not vary during testing like externally supported extensometers.
May be used on nearly any furnace with side entry cut-out for extensometers. Alternate configuration available for insertion between coils of induction heaters.
Use without cooling to 1200 C (2200 F). Optional small fan improves stability at highest temperatures.
All units come with high purity alumina ceramic rods.
Full bridge strain gaged design for compatibility with external electronics.
Versions available for use in vacuum and controlled atmospheres. Either water cooled or radiant heat transfer cooled versions are available for these applications.
Comes with a spare set of ceramic rods, several extra ceramic fiber cords and a high quality foam lined case.

Model 3448 with 25 mm gage length


Full bridge strain gaged design
Linearity: 0.15 %
Output: 2 to 4 mV/V nominal, depending on model
Excitation: 10 VDC recommended, 12 VDC or VAC max.
Temperature range: 1200 C max (2200 F), all versions


Rod tips as straight chisel, vee chisel, or conical point (specify) Air cooling fan, add suffix -AC

Ceramic cord orientation for furnaces or induction heaters (specify) Shunt Calibration Module

Model 3448 Available Versions: ANY combination of gage length and travel listed below is available, except as noted.

Ceramic rod lengths are made to fit furnaces as required.

Gage Length
10 mm 0.500 in.
25 mm 1.000 in.
50 mm 2.000 in.

Travel in Percent Strain:
± 51
± 10
± 20
+ 50 / -20

example: 20% strain in a 50 mm gage length version
results in total measuring range of 10 mm.

1For 10 mm and 0.5 inch gage lengths, the 5% travel
version is only available in short ceramic rod lengths.

For more information on calibration services or digital retrofits please contact us.



300 Buttertown Road
Emlenton, PA 16373
(724) 867-6664 or (800) 793-1870
FAX (724) 867-1346

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