Preliminary Results on New Prototypes of Precision Rh-0.5at%Fe Resistance Thermometers of Chinese Production

Given the practical impossibility of obtaining new precision Rh-0.5at%Fe resistance thermometers in recent years, the possible re-starting of the production of such thermometers in Yunnan (China) was explored by Istituto Nazionale di Ricerca Metrologica (INRIM). Ten prototypes of the new production were made available in early 2006. The paper reports the preliminary data from the testing performed to date on these prototypes at National Institute of Metrology (NIM) and Instytut Niskich Temperatur i Badan Strukturalnych (INTiBS). Although a problem with the alloy composition was detected, the reproducibility results on thermal cycling are very encouraging. Resistance-temperature ( R - T ) characteristics below 30 K, though not identical with those of similar thermometers formerly available from Tinsley and VNIIFTRI, are still suitable for accurate metrology.