Performance of Chromel versus Alumel and Nicrosil versus Nisil thermocouple assemblies in vacuum and argon between 1000/sup 0/C and 1200/sup 0/C
Prior work has shown that Nicrosil versus Nisil (Type N) thermocouples exhibit improved thermoelectric stability at elevated temperatures in oxidizing environments greater than existing nickel base thermocouple alloys. This research has evaluated the performance of Chromel versus Alumel and Nicrosil versus Nisil thermocouple assemblies in vacuum and argon between 1000/sup 0/C and 1200/sup 0/C. Both sheathed and bare thermocouple wires of various thicknesses were tested. The thermocouples were compared after exposure to the elevated temperatures by measuring thermoelectric drift from initial calibration data and by performing in-place inhomogeneity tests. Under these test conditions, comparable behavior was exhibited by the Type K and Type N thermocouples. However, several conclusions could be made. Thick, bare thermocouples did as well as sheathed thermocouples especially at elevated temperatures where reaction with insulating materials is likely for sheathed thermocouples. Stainless steel sheathed thermocouples tended to exhibit larger maximum errors than Inconel sheathed thermocouples which is a result of contamination by diffusion of sheath component species into the thermoelements. At 1200/sup 0/C, only the thickest thermocouples (bare or sheathed) survive without shorting or developing significant error for short exposure times. In general, the decalibrations of both types of thermocouples are similar between 1000/sup 0/C and 1200/sup 0/C in both vacuum and argon environments.
- Research Organization:
- Oak Ridge Y-12 Plant, TN (USA); Oak Ridge National Lab., TN (USA)
- DOE Contract Number:
- AC05-84OS21400
- OSTI ID:
- 6225724
- Report Number(s):
- Y/DV-362; CONF-8409109-5; ON: DE85000810
- Resource Relation:
- Conference: Industrial temperature measurement symposium, Knoxville, TN, USA, 10 Sep 1984; Other Information: Portions are illegible in microfiche products
- Country of Publication:
- United States
- Language:
- English
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