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Effect of Annealing on Drift in Type S Thermocouples Below $$900\, ^{\circ }\hbox {C}$$.
- Source :
-
International Journal of Thermophysics . Aug2015, Vol. 36 Issue 8, p1909-1924. 16p. - Publication Year :
- 2015
-
Abstract
- Type R and Type S platinum/platinum-rhodium thermocouples are amongst the most widely used high-temperature thermocouples, both for process measurement and as reference thermocouples. To achieve the lowest practical uncertainties, below $$1\, ^{\circ }\hbox {C}$$ , the thermocouples must be in a well-defined thermoelectric state. There are two annealing procedures in common use that leave the thermocouples in different states, leading to a potential ambiguity and uncertainty. This paper reports on experiments with Type S thermocouples clearly exposing the different drift characteristics for the two different annealed states. Thermocouples used above $$800\, ^{\circ }\hbox {C}$$ show the least drift when annealed at $$1100\, ^{\circ }\hbox {C}$$ and then passively quenched to room temperature. If used at lower temperatures, they exhibit drift, at temperatures as low as $$170\, ^{\circ }\hbox {C}$$ , with the drift peaking at $$0.3\, ^{\circ }\hbox {C}$$ to $$0.4\, ^{\circ }\hbox {C}$$ around $$300\, ^{\circ }\hbox {C}$$ to $$600 \, ^{\circ }\hbox {C}$$ . Thermocouples used below $$800\, ^{\circ }\hbox {C}$$ are best annealed at $$1100\, ^{\circ }\hbox {C}$$ , and then again at $$450\, ^{\circ }\hbox {C}$$ . In this state, they exhibit practically zero drift for temperatures up to about $$600 \, ^{\circ }\hbox {C}$$ . Advice on calibration procedures to minimise the effects of drift is given. [ABSTRACT FROM AUTHOR]
Details
- Language :
- English
- ISSN :
- 0195928X
- Volume :
- 36
- Issue :
- 8
- Database :
- Academic Search Index
- Journal :
- International Journal of Thermophysics
- Publication Type :
- Academic Journal
- Accession number :
- 109171669
- Full Text :
- https://doi.org/10.1007/s10765-015-1910-7