New adiabatic calorimeter for realization the triple point of water in metallic-sealed cell at NIS-Egypt

Abstract

The thermal metrology laboratory, at the National Institute for Standards (NIS-Egypt), has been working during the last three years on the development of metallic-sealed cells for the realization of the triple point of water (TPW), 273.16 K [H. Preston-Thomas, Metrologia 27, 3 (1990)]. A metallic-sealed cell has been already developed and characterized in the past [A. El Matarawy, M.G. Ahmed, Int. J. Metrol. Qual. Eng. 5, 401 (2014), M.G. Ahmed, A. El Matarawy, H.M. Abo Dorra, J. Phys. Sci. Appl. 1 (2015)]. The classical large triple point of water cell and metallic-sealed cell showed a discrepancy of 0.7 mK [A. El Matarawy, M.G. Ahmed, Int. J. Metrol. Qual. Eng. 5, 401 (2014)]. The main target of this work is to get the lowest possible uncertainty in calibrating Capsule Standard Platinum Resistance Thermometers (CSPRTs) under adiabatic conditions. The full system is composed of a metallic-sealed cell and an improved adiabatic calorimeter to increase as much as possible the thermal resistance between the cell and the inner adiabatic shield of the calorimeter. It gives also a reliable calculation of the heat capacity of the cell and the comparison copper block which accommodates several CSPRTs. With this new system the reproducibility of metallic-sealed cell was found to be 0.7 mK as described below. reproducibility of metallic-sealed cells is found to be less than 0.7 mK.