= Standard platinum resistance thermometer
= SPRT
{c}
{synonym}
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.<Guide on Secondary Thermometry: Industrial Platinum Resistance Thermometers by Jonathan Pearce and others>[§§1–2.2, printed pp. 5–11: industrial elements versus SPRTs and wire/film construction]{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>.<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]{ref} 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.
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