Long-Term Resistance and Ratio Stability of SPRTS, Comparing Metal Sheaths vs. Fused Silica Sheaths

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Long-Term Resistance and Ratio Stability of SPRTS, Comparing Metal Sheaths vs. Fused Silica Sheaths (112.93 KB)

An investigation of re-calibration results of metal-sheathed standard platinum resistance thermometer (SPRT) and fused silica-sheathed SPRTs was reported. The performance of metal-sheathed SPRTs could be as good as that of fused-sheathed SPRTs if the user could take care it very well. However, in fact, the long-term stability of metal-sheathed SPRTs is generally worse than that of fusesilica sheathed SPRTs due to the users' carelessness. The investigation results were discussed based on possible effects due to the sensor contamination, platinum oxidation, and mechnical shock, etc. To reduce calibration uncertainty and improve calibration reliability, two simple methods are introduced.