Pt100 2026-10-14
A Pt100 has nominal electrical resistance at .[ref]
Mercury Thermometer Alternatives: Platinum Resistance Thermometers (PRTs) by National Institute of Standards and Technology. Platinum Resistance Thermometers, opening explanation: conventional 100-ohm element at 0 °C
Here is the reference for the nominal element designation; it is distinct from the water triple point used in SPRT calibration. The following Pt100 local linear model deliberately stipulates one approximate response for calculations. Standard platinum resistance thermometer 2026-10-14
A standard platinum resistance thermometer uses very pure, annealed platinum with strain-limiting construction. An industrial platinum resistance thermometer commonly uses supported wire or a film. Their response curves differ.[ref]
The word standard describes the instrument's metrological role. Calibrated SPRTs realize specified interpolation intervals of the International Temperature Scale of 1990 and transfer reference temperatures to other thermometers.[ref]
Mercury Thermometer Alternatives: Platinum Resistance Thermometers (PRTs) by National Institute of Standards and Technology. Platinum Resistance Thermometers, opening explanation: SPRTs as ITS-90 interpolation tools
They are primary standards for realizing that practical scale, but their electrical resistance alone does not determine absolute thermodynamic temperature without calibration. Primary thermometry such as the corrected gas thermometer obtains thermodynamic temperature from a physical law. A reference in a comparison bath may be an SPRT; an individually calibrated industrial platinum resistance thermometer can also serve as a working reference with an appropriate uncertainty.