Optimization of realization routine of the carbon dioxide triple point in the cell designed for long stem resistance thermometers

B.G. Potapov1, A.A. Petukhov1, Ya.E. Razhba1, M.Yu. Ghavalyan1, V.G. Kytin1,2, N.A. Beketov3, A.I. Pokhodun3

1FSUE “VNIIFTRI”, Mendeleevo, Moscow region, Russia;
2M.V. Lomonosov Moscow State University, Moscow, Russia;
3D.I. Mendeleyev Institute for Metrology (VNIIM), St. Peterburg, Russia
potapov@vniiftri.ru,
petukhov@vniiftri.ru,
razhba@vniiftri.ru,
vkytin@vniiftri.ru,
n.a.beketov@vniim.ru,
a.i.pokhodun@vniim.ru

Al’manac of Modern Metrology № 1 (37) 2024, pages 80–90

Abstract. The results are presented of the realization of plateau of the carbon dioxide tripe point in the cell designed for long stem resistance thermometers. The effect was inves­tigated the routine of the cooling, freezing and heating of the cell on the shape of the plateau and the temperature of the triple point of carbon dioxide determined from the plateau. For realization of triple point of plateau the cell was located in the liquid thermostat. The rate of cooling and heating was controlled by the temperature of working liquid in the thermo­stat. The temperature of the working liquid in the thermostat was periodically varied to check the presence of solid and liquid phases of carbon dioxide. The optimal routine for realization of the plateau with minimal slope was proposed on the basis of obtained results. This significantly decreases the uncertainty of calibration of resistance thermo­meters in the cell of carbon dioxide triple point.

Keywords: International Temperature Scale (ITS-90), carbon dioxide triple point, long stem resistance thermometer.

Full texts of articles are available only in Russian in printed issues of the magazine.