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Thermocouple Research The performance of thermocouples consisting of alloy legs is often limited by inhomogeneities in the alloy composition. These inhomogeneities can be introduced in the initial manufacture of the wires, or they can be caused by physical or chemical changes in the wires upon heating to elevated temperatures. The NIST Thermometry Group is actively involved in developing fabrication techniques and constructing reference functions for accurate thermocouples consisting of two pure element legs. In particular, research focuses on gold versus platinum and platinum versus palladium thermocouples. Compared to the platinum-rhodium alloy thermocouples, gold versus platinum thermocouples have accuracies approximately ten times better, far superior homogeneity, and no measurable long term drift. Limitations of gold versus platinum thermocouples include a maximum usage temperature of 1000 ºC and incompatibility with certain manufacturing environments. Platinum versus palladium thermocouples show promise of extending the range of pure element thermocouples to temperatures of 1300 ºC or higher. For more information, contact Dean Ripple at dean.ripple@nist.gov |
Last Updated on: 2/25/04
| Contacts Tests and Fees Calibration Uncertainties Industrial Thermometers Low Temperature SPRTs Thermocouples |
| Bibliography Fixed Points Humidity IPRTs ITS 90 Liquid in Glass Meas. Assurance Publications RTP SPRTs SRMs Tempmeko 2001 Thermistors Thermocouples Thermodynamic |
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Precision Themometry Workshop: ITS 90 Fixed Point Cell Mini Workshop: Liquid In
Glass Thermometer Mini Workshop: |
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Calibration for RTP |
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