Measurements to determine the EMF versus temperature relation of Pt/Pd thermocouple in the temperature range from 25 to 450 C were carried out in stirred liquid and salt baths.
The temperature of the bath was determined with a 25 X standard platinum resistance thermometer (SPRT) calibrated according to ITS-90.
A water baths upplied by Hart Scientific was used from 25 to 95 C, an oil bath from 95 to 270 C, and a salt bath from 220 to 450 C. All baths were manufactured by Hart Scientific.
For mixing the bath fluid a stirring propeller system is used to eliminate both horizontal and vertical gradients.
The baths consist of two stainless steel tanks.
The heater and propeller are fitted at the outside stainless steel tank.
The temperature controller is connected to a platinum resistance thermometer as the control sensor.
The inside stainless steel tank has a depth of 60 cm and is used for thermometer calibrations.
The horizontal and vertical temperature stability of the bath is ±0.015 C.