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Isothermal Properties for Argon

The following adjustments were made to the specified data range:

Fluid Data

Isothermal Data for T = 273.16 K

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Auxiliary Data

Reference States, default for fluid

Additional fluid properties


Equation of state, auxiliary model, and melting curve

Tegeler, Ch.; Span, R.; Wagner, W., A New Equation of State for Argon Covering the Fluid Region for Temperatures from the Melting Line to 700 K at Pressures up to 1000 MPa, J. Phys. Chem. Ref. Data, 1999, 28, 3, 779-850. [all data]

Auxiliary model

Stewart, R.B.; Jacobsen, R.T., Thermodynamic Properties of Argon from the Triple Point to 1200 K at Pressures to 1000 MPa, J. Phys. Chem. Ref. Data, 1989, 18, 2, 639-798. [all data]

Auxiliary model

Younglove, B.A., Thermophysical Properties of Fluids. I. Argon, Ethylene, Parahydrogen, Nitrogen, Nitrogen Trifluoride, and Oxygen, J. Phys. Chem. Ref. Data, 1982, 11, 1-11. [all data]

Thermal conductivity

Perkins, R.A.; Friend, D.G.; Roder, H.M.; Nieto de Castro, C.A., Thermal Conductivity Surface of Argon: A Fresh Analysis, Int. J. Thermophys., 1991, 12, 6, 965-984. [all data]

Auxiliary model and viscosity

Younglove, B.A.; Hanley, H.J.M., The Viscosity and Thermal Conductivity Coefficients of Gaseous and Liquid Argon, J. Phys. Chem. Ref. Data, 1986, 15, 4, 1323-1337. [all data]

Surface tension

Lemmon, E.W.; Penoncello, S.G., The Surface Tension of Air and Air Component Mixtures, Adv. Cryo. Eng., 1994, 39, 1927-1934. [all data]

Additional Information

Equation of state

The estimated uncertainty in density is less than 0.02% for pressures up to 12 MPa and temperatures up to 340 K with the exception of the critical region and less than 0.03% for pressures up to 30 MPa and temperatures between 235 and 520 K. Elsewhere, the uncertainty in density is generally within 0.2%. In the region with densities up to half the critical density and for temperatures between 90 and 450 K, the estimated uncertainty of calculated speeds of sound is in general less than 0.02%. In the liquid and supercritical regions, the uncertainty is less than 1%. The uncertainty in heat capacities is within 0.3% for the vapor and 2% for the liquid. The formulation gives reasonable extrapolation behavior up to very high pressures (50 GPa) and temperatures (17000 K).

Thermal conductivity

The uncertainty in thermal conductivity is 2%.


The uncertainty in viscosity is 2%, except in the dilute gas, where the uncertainty is 0.5%.

Thermal conductivity

The uncertainty in thermal conductivity is 2.2%.

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 9.1) of this database in the the next couple of months. Information on REFPROP version 9.1 can be found here. REFPROP version 9.1 includes additional data and features not available from this site.