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it uses the triple point of water (273.16 K), rather than the freezing point of water (273.15 K), as a defining point; |
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it extends to lower temperatures: 0.65 K instead of 13.8 K; |
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it is in closer agreement with thermodynamic temperatures; |
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it has improved continuity and precision; |
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it has a number of overlapping ranges and sub-ranges; |
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in certain ranges it has alternative but substantially equivalent definitions; |
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it includes the helium vapour pressure scales; |
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it includes an interpolating gas thermometer as one of the defining instruments; |
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the range of the platinum resistance thermometer as defining instrument has been extended from 630 °C up to the silver point, 962 °C; |
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the Pt/10 % Rh-Pt thermocouple is no longer a defining instrument of the scale; |
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the range based upon the Planck radiation law begins at the silver point instead of at the gold point, but options exist for using any one of the silver, gold or copper points as reference points for this part of the scale.
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Summary
