This guide is intended for use with dry-well calibrators without the use of fluids or thermal contact enhancing media over a range of -90C to 1200C. This guide describes the essential features of dry-well calibrators used for the purpose of thermometer calibration in either the direct or indirect comparison modes. The direct mode is defined as using the calibration provided with the control sensor in the calibrator while the indirect mode utilizes an external measurement system. This guide proposes tests that can be performed to define uncertainty limits and how they may be used in creating an uncertainty budget. Measurement practices to optimize the calibration accuracy of a dry-well calibrator are discussed. Dry-well calibrator accessories such as built in reference thermometers, switch testing circuitry, computer communications, current loops, etc. will not be discussed.
Dry-well calibrators are increasingly used in traceable temperature measurement. Euramet has produced a good document pertaining to calibration of dry-well calibrators, however, the guide does not directly address use of dry-well calibrators. As a result direct application of the Euramet guide in evaluating the uncertainties associated with use will result in an overestimate of uncertainties. Additionally, no formal guidance pertaining to usage is available.
The title and scope are in draft form and are under development within this ASTM Committee.
Citing ASTM Standards
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