Updated uncertainty budgets for NIST thermocouple calibrations

Abstract

We have recently updated the uncertainty budgets for calibrations in the NIST Thermocouple Calibration Laboratory. The purpose for the updates has been to 1) revise the estimated values of the relevant uncertainty elements to reflect the current calibration facilities and methods, 2) provide uncertainty budgets for every standard calibration service offered, and 3) make the uncertainty budgets more understandable to customers by expressing all uncertainties in units of temperature (°C) rather than emf. We have updated the uncertainty budgets for fixed-point calibrations of type S, R, and B thermocouples and comparison calibrations of type R and S thermocouples using a type S reference standard. In addition, we have constructed new uncertainty budgets for comparison calibrations of type B thermocouples using a type B reference standard as well as using both a type S and type B reference standard (for calibration over a larger range). We have updated the uncertainty budgets for comparison calibrations of base-metal thermocouples using a type S reference standard and alternately using a standard platinum resistance thermometer reference standard. Finally, we have constructed new uncertainty budgets for comparison tests of noble-metal and base-metal thermoelements using a type S reference standard. A description of these updates is presented in this paper.