Triple point of water Unit Converter

Definition of Triple point of water unit

The triple point of water is the unique temperature and pressure at which ice, liquid water, and water vapor coexist in thermodynamic equilibrium: 273.16 kelvins (0.01 °C) at 611.657 pascals.

History of Triple point of water unit

The triple point concept emerged from nineteenth-century thermodynamics, as scientists mapped phase relationships and recognized invariant combinations of temperature and pressure. In 1954, the 10th General Conference on Weights and Measures assigned water’s triple-point temperature the exact value 273.16 K, making it a fundamental fixed point for the Kelvin scale. This definition remained central to temperature metrology until the 2019 SI revision, which defined the kelvin through the Boltzmann constant. The triple point of water nevertheless remains an important practical calibration reference.

Applications of Triple point of water unit

Today, the triple point of water serves as a high-precision reference in thermometry and laboratory calibration. Specialized sealed cells establish the equilibrium state, allowing scientists to check thermometers, realize temperature scales, and compare national standards. It also appears in education, phase-diagram experiments, and discussions of the SI kelvin and fundamental measurement uncertainty.

Complete list of Triple point of water unit conversion