Expression of the uncertainty of measurement in the calibration of thermometers - Part I: Standard platinum resistance thermometers

A model is proposed for the calibration of a standard platinum resistance t hermometer (SPRT) in accordance with the BIPM recommended procedures to rea lize the International Temperature Scale of 1990 (ITS-90). The model is use d to obtain the standard uncertainty of measurement associated with the tem perature indicated by the thermometer. The difference between calibration u ncertainty and user's uncertainty is established. Equations are illustrated by an example that considers the ITS-90 subrange from 273.15 K to 692.677 K. The approach closely follows the rules in the ISO Guide to the Expressio n of Uncertainty in Measurement.