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Isothermal Properties for Methane

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, Normal Boiling Point Convention

Additional fluid properties


Equation of state, auxiliary model, and melting curve

Setzmann, U.; Wagner, W., A New Equation of State and Tables of Thermodynamic Properties for Methane Covering the Range from the Melting Line to 625 K at Pressures up to 1000 MPa, J. Phys. Chem. Ref. Data, 1991, 20(6), 1061-1151. [all data]

Auxiliary model and thermal conductivity

Friend, D.G.; Ely, J.F.; Ingham, H., Thermophysical Properties of Methane, J. Phys. Chem. Ref. Data, 1989, 18, 2, 583-638. [all data]

Auxiliary model, viscosity, and dielectric constant

Younglove, B.A.; Ely, J.F., Thermophysical properties of fluids. II. Methane, ethane, propane, isobutane and normal butane, J. Phys. Chem. Ref. Data, 1987, 16, 577-798. [all data]

Surface tension

Somayajulu, G.R., A Generalized Equation for Surface Tension from the Triple Point to the Critical Point, Int. J. Thermophys., 1988, 9, 4, 559-566. [all data]

Additional Information

Equation of state

The uncertainties in density are 0.03% for pressures below 12 MPa and temperatures below 350 K and up to 0.07% for pressures less than 50 MPa. For the speed of sound, the uncertainty ranges from 0.03% (in the vapor phase) to 0.3% depending on temperature and pressure. Heat capacities may be generally calculated within an uncertainty of 1%.

Thermal conductivity

The uncertainty in thermal conductivity of the dilute gas between 130 and 625 K is 2.5%. For temperatures below 130 K, the uncertainty is less than 10%. Excluding the dilute gas, the uncertainty is 2% between 110 and 725 K at pressures up to 70 MPa, except near the critical point which has an uncertainty of 5% or greater. For the vapor at lower temperatures and the dense liquid near the triple point, an uncertainty of 10% is possible.


N.B. all temperatures on IPTS-68

The uncertainty in viscosity is 2%, except in the critical region which is 5%.

Dielectric constant

The uncertainty in dielectric constant is 0.05%.

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.