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Session:
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1B - Temperature I
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Date & Time:
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Monday August 7, 10:45 AM - 12:15 PM
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Paper Title:
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Determination of Uncertainties for Temperature Fixed Points & their ITS-90 Subranges
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Speaker:
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Douglas Scheck, Metrology Technician
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CoAuthors:
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Speaker Info
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Company:
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Bionetics/Air Force Primary Standards Laboratory
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Address:
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813 Irving-Wick Dr. SW
Heath, OH, 43056, United States
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Phone:
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740-788-5437
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Fax:
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740-788-5474
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Email:
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Doug.Scheck@afmetcal.af.mil
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Abstract:
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The International Temperature Scale of 1990 (ITS-90) defines temperature values over the range of -259.3467 to 961.78 °C at fourteen Fixed Points. ITS-90 temperature values between these Fixed Points are defined using a Standard Platinum Resistance Thermometer (SPRT) as an interpolation device. In order to determine the uncertainty of the values produced by an SPRT between the Fixed Points an uncertainty propagation analysis must be performed. Due to variations between SPRTs (non-uniqueness) the uncertainty propagation is different for each SPRT. This paper shows data for fixed points ranging from the Triple Point of Argon (-189.3442 °C) to the Freezing Point of Zinc (419.527 °C). The uncertainties at the fixed points are then used to determine the uncertainties of the applicable subranges. The method for determining the uncertainty propagation of a typical SPRT is explained in detail. Examples are given for ITS-90 subranges 4, 7, and 8. The method described may be applied to other ITS-90 subranges.
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