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Isobaric Properties for Water

The following adjustments were made to the specified data range:

Fluid Data

Isobaric Data for P = 1.0000 bar

Temperature (C)Pressure (bar)Density (g/ml)Volume (ml/g)Internal Energy (kJ/kg)Enthalpy (kJ/kg)Entropy (J/g*K)Cv (J/g*K)Cp (J/g*K)Sound Spd. (m/s)Joule-Thomson (K/bar)Viscosity (uPa*s)Therm. Cond. (W/m*K)Phase

Auxiliary Data

Reference States, default for fluid

Additional fluid properties


Equation of state and auxiliary model

Wagner, W.; Pruss, A., The IAPWS formulation 1995 for the thermodynamic properties of ordinary water substance for general and scientific use, J. Phys. Chem. Ref. Data, 2002, 31, 2, 387-535. [all data]

Auxiliary model

Saul, A.; Wagner, W., A Fundamental Equation for Water Covering the Range From the Melting Line to 1273 K at Pressures up to 25000 MPa, J. Phys. Chem. Ref. Data, 1989, 18, 4, 1537-1564. [all data]

Thermal conductivity

IAPWS, Revised Release on the IAPS Formulation 1985 for the Thermal Conductivity of Ordinary Water Substance, International Association for the Properties of Water and Steam, London, 1998, 23, retrieved from http://www.iapws.org/relguide/thcond.pdf. [all data]

Thermal conductivity and viscosity

Kestin, J.; Sengers, J.V.; Kamgar-Parsi, B.; Levelt Sengers, J.M.H., Thermophysical Properties of Fluid H2O, J. Phys. Chem. Ref. Data, 1984, 13, 1, 175-183. [all data]


IAPWS, Revised Release on the IAPS Formulation 1985 for the Viscosity of Ordinary Water Substance, International Association for the Properties of Water and Steam, Erlangen, Germany, 1997, 15, retrieved from http://www.iapws.org/relguide/visc.pdf. [all data]

Surface tension

International Association for the Properties of Water Steam, Viscosity of thermal conductivity of heavy water substance in Physical Chemistry of Aqueous Systems: Proceedings of the 12th International Conference on the Properties of Water and Steam, Orlando, FL, 1994, a107-a138. [all data]

Dielectric constant

Fernandez, D.P.; Goodwin, A.R.H.; Lemmon, E.W.; Levelt Sengers, J.M.; Williams, R.C., A Formulation for the Static Permittivity of Water and Steam at Temperatures from 238 K to 873 K at Pressures up to 1200 MPa, Including Derivatives and Debye-Huckel Coefficients, J. Phys. B: At. Mol. Opt. Phys., 1997, 26, 4, 1125-1165. [all data]

Melting curve

Wagner, W.; Saul, A.; Pruss, A., International Equations for the Pressure Along the Melting and Along the Sublimation Curve of Ordinary Water Substance, J. Pharm. Sci, 1994, 23, 3, 515-527. [all data]

Additional Information

Equation of state

The uncertainty in density of the equation of state is 0.0001% at 1 atm in the liquid phase, and 0.001% at other liquid states at pressures up to 10 MPa and temperatures to 423 K. In the vapor phase, the uncertainty is 0.05% or less. The uncertainties rise at higher temperatures and/or pressures, but are generally less than 0.1% in density except at extreme conditions. The uncertainty in pressure in the critical region is 0.1%. The uncertainty of the speed of sound is 0.15% in the vapor and 0.1% or less in the liquid, and increases near the critical region and at high temperatures and pressures. The uncertainty in isobaric heat capacity is 0.2% in the vapor and 0.1% in the liquid, with increasing values in the critical region and at high pressures. The uncertainties of saturation conditions are 0.025% in vapor pressure, 0.0025% in saturated liquid density, and 0.1% in saturated vapor density. The uncertainties in the saturated densities increase substantially as the critical region is approached.

Thermal conductivity

For the uncertainties in the thermal conductivity, see the IAPWS Release.


For the uncertainties in the viscosity, see the IAPWS Release.

Surface tension

For the uncertainties in surface tension, see the IAPWS Release.

Important Information About This Data

The data above are from an older version of the NIST Reference Fluid Thermodynamic and Transport Properties Database (REFPROP version 7). We will be updating our site to use the newer version (version 10) of this database in the future. Information on REFPROP version 10 can be found on theREFPROP web page. REFPROP version 10 includes additional data and features not available from this site.