International Association for the Properties

The phase diagram features four phase regions, three phase boundaries, and two points of particular interest the triple point (TP) and the supercritical point (CP). Values for TP and CP from The International Association for the Properties of Water and Steam6 (IAPWS) are 273.16 K and 611.657 Pa (IAPWS, 2002) and 647.096 K and 22.064 MPa (IAPWS, 2002), respectively. Three of the phases (solid, liquid, and gas) are bounded by equilibrium... 

The International Association for the Properties of Water and Steam (IAPWS) provides internationally accepted values and formulations for the properties of light and heavy steam, water, and selected aqueous solutions for scientific and industrial applications. IAPWS Releases and Guidelines can be obtained online at http //www.iapws.org. 

Marshall, W.L. and Franck, E.U., Paper presented at International Association for the Properties of Steam, Sept. 1979, Munich, West Germany... 

IAPWS, Guideline on the Henry s Constant and Vapor-Liquid Distribution Constant for Gases in H20 and D20 at High Temperatures, The International Association for the Properties of Water and Steam, Kyoto, Japan (2004)... 

M. Nakahara, T. Tbrbk, N. Takisawa, and J. Osugi, 7. Chem. Phys., 76, 5145(1982). International Association for the Properties of Steam The lAPS Formulation1985for the Viscosity of Ordinary Water Substance, 1985. 

While standardizing the values for the thermophysical properties of water and steam, also known as water substance, the International Association for the Properties of Steam (lAPS) has established formulations for various properties. 

Horacio R. Corti received his Ph.D. at the University of Buenos Aires (UBA), Argentina in 1980. He became a postdoctoral fellow at the Central Electricity Research Laboratories, CEGB, Leatherhead, U.K. in 1981. Since 1977, he has been a scientific staff member at the National Atomic Energy Commission (CNEA) in Argentina. Since 1984, he has been professor of chemistry at the Facultad de Ciencias Exactas y Naturales, UBA, where he became full professor of physical chemistry in 1996. He has been a member of the National Research Council (CONICET) since 1987 and is the coordinator of the Argentine-Brazilian Committee of the International Association for the Properties of Water and Steam. He participates in international cooperative... 

Water, in pure or nearly pure form, is widely used both as a process stream and (as cooling water or steam) as a heat-transfer fluid. Because of its importance, international standards exist for its thermophysical properties. These standards are set by the International Association for the Properties of Water and Steam (lAPWS see www.iapws.org). 

This table summarizes the vapor pressure, enthalpy (heat) of vaporization, and surface tension of water as accepted by the International Association for the Properties of Water and Steam (www.iapws.org) for general and scientific use. The vapor pressure and heat of vaporization are calculated from the equation of state of Wagner and Pruss (Ref. 1). The temperature scale is lTS-90. Additional calculations at state points not listed below can be obtained by using the NIST Standard Reference Data program REFPROP (www.nist.gov/srd/nist23.htm) or the water-specific program Steam (www.nist.gov/srd/nistl0.htm). 

Wagner, W. and Pruss, A., The lAPWS Formulation 1995 for the Thermodynamic Properties of Ordinary Water Substance for General and Scientific Use,/. Phys. Chem. R. Data, 31, 387, 2002. International Association for the Properties of Water and Steam, Release on the surface tension of ordinary water substance. Physical Chemistry of Aqueous Systems Proceedings of the 12th International Conference on the Properties of Water and Steam, Orlando, Florida, September 11-16, 1994, pp. A139-A142. 

The values of the vapor (sublimation) pressure of ice in this table were calculated from the equation recommended by the International Association for the Properties of Steam (lAPS) in 1993. Temperature values correspond to the lTS-90 temperature scale. The uncertainty in the pressure is estimated to be 0.1% for t > -25°C and 0.5% for t < -25°C. The first entry in the table is the triple point of water. 

This table gives values of the melting temperature of ice at various pressures, as calculated from the equation for the ice 1 -liquid water phase boundary recommended by the International Association for the Properties of Steam (lAPS). Temperatures are on the lTS-90 scale. See the Reference for information on forms of ice that exist at higher pressures. The transition points for transformations of the various forms of ice (in each case in equilibrium with liquid water) are ... 

Data are based on the equation of state recommended by the International Association for the Properties of Steam in 1984, as presented in Haar, Gallagher, and KeU, NBS-NRC Steam Tables... 

This table gives properties of compressed water and superheated steam at selected pressures and temperatures. The properties included are density p, enthalpy//, entropy S, heat capacity at constant pressure C, and static dielectric constant (relative permittivity). The table was generated from the formulation approved by the International Association for the Properties of Water and Steam for general and scientific use. The reference state for this table is the liquid at the triple point, at which the internal energy and entropy are taken as zero. A duplicate entry in the temperature column indicates a phase transition (liquid-vapor) at that temperature property values are then given for both phases. In the 100 MPa section of the table, an entry is given at the critical temperature, 647.10 K. Temperatures refer to the ITS-90 scale, on which the normal boiling point of water is 373.12 K (99.97°C). 

---