mechtly
Wed, 01 Sep 2010 15:36:28 -0700
My source of information on questions of temperature is NIST Technical Note 1265; Guidelines for Realizing the International Temperature Scale of 1990 (ITS-90), by B.W. Mangum and G. T. Furukawa, August 1990.
The fixed points of the ITS-90 are Freezing Points, Melting Points, Boiling Points, or Triple Points of various substances; atoms or molecules. More than twenty seven are included. With respect to calibration: "The ITS-90 was designed by the Consultative Committee on Temperature (CCT) in such a manner that temperature values obtained on it do not deviate from the kelvin thermodynamic temperature values by more than the uncertainties of the latter values at the time the ITS-90 was adopted." "The size of the kelvin is defined to be 1/273.16 of the thermodynamic temperature of the triple point of water." t/(deg C) = T/K - 273.15; defines thermodynamic temperatures in Celsius. t(subscript 90) denotes ITS-90 temperatures also in Celsius. The "International Practical Temperature Scale" IPTS-of 1968 (amended in 1975). has been formally abrogated. t and t(subscript 90) are not the same. >---- Original message ---- >>Date: Wed, 01 Sep 2010 14:08:49 -0500 >>From: "James R. Frysinger" <j...@metricmethods.com> >>Subject: [USMA:48447] Re: kelvin >>To: "U.S. Metric Association" <usma@colostate.edu> >> >> >>The kelvin scale does NOT calibrate the Celsius scale. They are defined >>together by ITS-90. >> >>Jim