engleski

Multi-Entrance Fixed Points as an Alternative to the Equalizing Block

The uncertainty of comparison calibrations is often limited by temperature gradients and the stability of the isothermal zone. Traditionally, an equalizing block inserted into a bath or furnace is used to provide an isothermal zone during calibration. In this paper, the design and performance of a multi-entrance fixed point (MEFP) filled with mercury is described, with the goal to replace an equalizing block with the phase transition of mercury during melting/freezing. During this investigation, three thermometers were calibrated against a standard in the same bath at − 39 ˚ C, using both the standard equalizing block and MEFP. The measurement results clearly indicate that use of MEFP decreases the uncertainty contributions from temperature gradients and the stability of the bath by an order of magnitude compared to the standard equalizing block.

Comparison calibration; Equalizing block; Multi-entrance fixed point

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