A fixed point is a reproducible physical event that has a defined temperature value assigned on the ITS90. An example of a conventional fixed point used in temperature calibrations is the freezing point of a pure metal such as Tin.
Tin, for example, freezes (goes through the transition from a solid to a liquid) at 231.928 °C
Our extensive list of thermal calibration fixed points allows CCPI Europe to calibrate thermocouples and platinum resistance thermometers over the operational range required by customers.
The emf output of a thermocouple is measured when tested during a fixed-point transition and therefore the absolute value and difference from standard output tables can be established for that temperature point. A reference thermocouple calibration is conducted by measuring the output of the thermocouple at a number of these fixed points and from the test results, developing an individual emf output curve for the thermocouple.
The CoC and PdC fixed points unlike most eutectic conventional pure metal fixed points are examples of a new range of metal carbide fixed points developed by the NPL (National Physical Laboratory) to help increase accuracies in the high temperature range above 1100 °C.
