The new international temperature scale of 1990 (ITS-90)

Abstract

A new international temperature scale, the ITS-90, will replace the International Practional Temperature Scle of 1968 (amended edition of 1975), IPTS-68(75), on 1 January 1990. Temperatures on the ITS-90 will agree more closely with thermodynamic temperatures; therefore, the ITS-90 represents a substantial improvement over the IPTS-68(75). Fortunately for the clinical laboratory community, the change in the scale will be at most only 0.05°C or less in the range from 0 to 60°C, but corrections in primary calibrations should be made so that the calibrations are based on the ITS-90.