Temperature

The unit of temperature is kelvin.

The temperature is defined by the thermodynamic temperature scale. Thereby certain temperatures are assigned to a set of fixed points. The most important fixed point defining the unit of the thermodynamic temperature kelvin is the triple point of water corresponding to a thermodynamic temperature of 273,16 K, or a Celsius temperature of 0,01 °C.

At BEV the temperature scale, which is called „ITS 90“ according to an international agreement, is realized by primary and secondaryfixed reference points in the range from –189,3442 °C to 1084,62 °C:

• Triple point of argon (-189,3442 °C)
•  Triple point of mercury (-38,8344 °C)
•  Triple point of water (0,01 °C)
•  Melting point of gallium (29,7646 °C)

Freezing points of:

• indium (156,5985 °C)
• tin (231,928 °C)
• zinc (419,527 °C)
• aluminum (660,323 °C)
• silver (961,78 °C)
• copper (1084,62 °C)

Between thefixed points the temperature scale is realized by high precision platinum resistance thermometers up to the silver point and above by precision thermo-elements (Pt/Pd).

Verification of thermometers

Thermometers are subject to mandatory verification in Austria. Glass thermometers are generally admitted for verification. Electric and electronic thermometers, respectively, are only admitted for verification, if they are type approved by the BEV. The verification of thermometers is carried out according to the measurement range either by the legal metrology authority or by an accredited verification body. The interval for subsequent verification is five years for glass thermometers, two years for electric thermometers.