ITS-90
ITS-90 is the current version of the International Temperature Scale. It gives defining values in kelvins of various events over a wide range of temperatures. Although the kelvin is defined using absolute zero (0 K) and the triple point of water (273.16 K), it is impractical to use this definition at temperatures very different form the triple of water. The items on the scale can thus be used to calibrate instruments over a wide range of temperatures. The table belows shows some items on the scale.
| Fixed point | Temperature (K) |
|---|---|
| Triple point of neon | 24.5561 |
| Triple point of hydrogen | 13.81 |
| Triple point of oxygen | 54.361 |
| Freezing point of oxygen | 90.188 |
| Triple point of water | 273.16 |
| Freezing point of tin | 505.1181 |
| Freezing point of silver | 1234.93 |
| Freezing point of copper | 1357.77 |
Sources
- Physics, Patrick Fuller, pub. 1994 by Heinemann.
- Internet resource for the International Temperature Scale of 1990