The platinum palladium thermocouple as transfer standard in the temperature range 600 C - 1100 C
The introduction of the international temperature scale of 1990 and the growing request for accurate temperature measurements for calibration and testing purposes have reinforced the need for reproducible transfer standards in the temperature range from 600 C to 1100 C or even to 1300 C. The use of the platinum-palladium thermocouple for precision thermometry in the temperature range 600 C - 1100 C was investigated by preparing six thermocouples with wires of different nominal purity, from three manufacturers. The evaluation was carried out through calibrations against a reference S-type thermocouple and, particularly, at the freezing point of copper, with tests at variable immersion at the copper and silver points and, also, up to 1300 C. Properties assessed with this work are summarised including: (i) the third-order polynomial describing the Emf-vs.-temperature relation; (ii) the repeatability of the freezing point of copper (1084.62 C) to within 0.1 C for long-term, high temperature exposure; (iii) the stability of calibration curve, typically to within 0.2 C for exposure to high temperatures for up to 650 hours.
Bibliographic Reference: Paper presented: Metrologie 93, Lille (FR), October 19-21, 1993
Availability: Available from (1) as Paper EN 37701 ORA
Record Number: 199311316 / Last updated on: 1994-11-28
Original language: en
Available languages: en