Study on the realization of tin point

Tin-point cells were fabricated using high grade tin samples purchased from some different metal sources. Temperature measurements during the solid-liquid equilibrium condition, under which the tin point is defined, were conducted for evaluating the quality of the cells. Different methods for the realization of tin point were compared by means of the fabricated cells. Comparisons of tin-point temperatures realized using the conventional and the newly developed cells were also conducted. On the other hand, chemical assay provided by the tin sample manufacturer was used to estimate the tin point departure from that ideally defined by the International Temperature Scale of 1990 (ITS-90). The tin point departure, the cell comparison results and the analysis of the temperature measurements during the solid-liquid phase change were discussed for estimating the uncertainty of tin-point realization due to impurity existence. The present paper outlines the apparatus which includes the tin cell and the furnace, the temperature measurements and the evaluation of impurity effect to the tin point realization.