[Video Introduction] Methods of Temperature Calibration - What are Comparison Calibration and Fixed Point Calibration?

Introduction to temperature calibration methods. This explains the differences between comparative calibration and fixed-point calibration.

There are two methods for calibrating temperature measuring instruments such as dial thermometers, resistance thermometers (Pt100 and Pt1000), and thermocouples: fixed point calibration and comparative calibration. ■ Fixed Point Calibration Through a unique three-point calibration, the most accurate calibration at temperature fixed points is achieved. The triple point refers to the condition where the three phases of a substance are in thermodynamic equilibrium. For water, the triple point is defined as 0.01°C according to the International Temperature Scale (ITS-90). This means that the quantitative ratio of liquid water, water vapor, and ice remains unchanged. Reaching the triple point requires a significant amount of time and effort, but once achieved, it can maintain a stable temperature for a long period. By achieving a constant temperature condition, the deviation of the thermometer can be verified most accurately. Fixed point calibration is performed with the target thermometer used as a reference thermometer, meeting the requirements for reproducibility and high precision. ■ Comparative Calibration This method involves comparing the thermometer being calibrated with a reference thermometer that has been calibrated by a higher authority. Comparative calibration is conducted using a constant temperature bath, block gauge, or electric furnace. The probe of the thermometer being calibrated is inserted into the calibration device, and the instrument deviation is recorded at several calibration points in comparison to the reference thermometer. The use of a traceable reference thermometer allows for calibration at various required levels of accuracy.

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