Reliant Technology LLC.
2334 E Boulder Street
Colorado Springs, CO 80909 USA
Your Reliant extensometer should only be used for tests within its rated temperature range. Operation outside of this range can cause permanent damage to the extensometer and or cable.
Moisture and water can easily damage the strain gages used in your extensometer. Short term condensation normally does not cause permanent damage,
but continued exposure can degrade the strain gages and wiring and lead to early failure.
If your extensometer must be used where condensation may form, the extensometer should be dried as soon as possible (placing the extensometer in an oven at 40 °C [100 °F] for a few minutes works well). Also, storing your extensometer in a its case with a desiccant is recommended. Your Reliant extensometer may be used with most non-polar liquids without causing damage.
For applications where exposure to water is required, special protective coatings for the strain gages are available. Your Reliant extensometer should only be used for tests within its rated temperature range. Operation outside of this range can cause permanent damage to the extensometer and or cable.
Your extensometer will perform best and last longer with regular cleaning. Isopropyl alcohol and cotton swabs can be used to remove scale, grease, and grit from the extensometer. However, do not touch or rub the strain gages and wiring with the swab and never clean your extensometer with water based cleaners. Applying light oil to the spring plungers (if equipped) will extend their useful life.
All Reliant extensometers are designed for use through specimen failure. Mechanical stops are incorporated in your extensometer’s design to protect it from damage due to over-travel. However, testing through failure will increase the likelihood of the knife edges to chip or dull. This is normal wear and a spare set of knife edges is included with most models.
If your extensometer becomes damaged or worn, please contact us; extensometers can typically be repaired or rebuilt to function as new.
Most of Reliant’s extensometers are designed with a full, 350 Ohm, Wheatstone bridge.
Recommended excitation voltage is 5 or 10 VDC , however, some manufacturers
(such as Instron) use an AC excitation voltage. The output of your Reliant extensometer is proportional to the excitation voltage. This output is expressed in
millivolts per volt (mV/V). For example: For an extensometer with a rated output of 2.538 mV/V, you should expect the full scale output will be 25.280 millivolts when
the extensometer is excited by exactly 10 volts. The Inspection Certificate provided with your extensometer contains this data.
Strain gage based extensometers are passive instruments. They can not generate their own signal and as such must be connected to some external electronics. Typically, the electronics provide the excitation voltage to the extensometer and amplify the low voltage output signal to a high level DC voltage.
Your extensometer typically will require calibration with your electronics for it to read correctly. This process is generally quite straightforward and most calibration companies provide this service. For systems with a dedicated strain channel, your extensometer will typically be provided with the proper connector to directly plug-in to your electronics. For data acquisition systems or chart recorders, a signal conditioner is typically required. Reliant can provide signal conditioning electronics calibrated with your extensometer to allow direct connection to a chart recorder or data acquisition card.
Using an extensometer calibrator stand:
Extensometer calibration requires a precise tool to accurately measuring If you have many extensometers and wish to calibrate them to calibrate Reliant Technology’s model CERHV - Very High Resolution Extensometer Calibrator is an ideal way to perform extensometer calibrations.
Using a calibration service:
Reliant extensometers can be easily calibrated by any calibration service familiar with extensometers and materials testing equipment.
Using electronics from Reliant:
If you purchased your Reliant extensometer with signal conditioning electronics, the system will be shipped fully calibrated. No further initial calibration will be required for use. For periodic re-calibration, the extensometer and electronics can be calibrated by any qualified calibration service or the system can be returned to Reliant for calibration.
Quick verification of your system:
For a quick and easy way to verify your electronics, Reliant can provide your extensometer with our Shunt Calibration Plug. The Shunt Calibration Plug is a potted resistor(s) used to transfer or verify your extensometer’s calibration to your electronics. Complete details are provided on the Shunt Calibration Plug instruction sheet.
The following procedure is typical for calibrating an extensometer. Most calibrations will be in tension. If you need to calibrate your extensometer for both tension and compression, please refer to the notes at the end of this section.
An extensometer calibrator with the required measuring range, accuracy, and resolution will be needed to perform the calibration as well as the manuals for your particular test machine’s electronics.
The shunt calibration method can also be used to set-up your electronics based on the inspection certificate provided by Reliant.
The inspection certificate contains this data in mV/V, % strain, and VDC. To perform the shunt calibration, a shunt resistor with the resistance value specified on the inspection certificate is placed across one arm of the Wheatstone bridge, and the shift in output is recorded. This output shift may be displayed in millivolts, % strain, or Volts DC.
With the extensometer attached to a specimen at its gage length setting (zero pin carefully removed if so equipped) and zero the electronics. Next, engage the shunt calibration resistor and adjust the conditioner’s gain to arrive at the precise reading listed on the inspection certificate.
Many strain gage signal conditioners allow for shunt calibration. They often provide a location on the conditioner’s board for the resistor to be soldered. It is important that the resistor(s) be placed across the correct leads specified by the shunt calibration data. Most tension calibrations will be between RED and GREEN leads.
2334 E Boulder Street
Colorado Springs, CO 80909 USA
If you have any questions or would like a quote, please contact us HERE.
If your extensometer is in need of service or repair, please fill out an RMA form HERE.