This specification covers the isobutane thermophysical property tables which are used in the calculation of the pressure-volume-temperature (PVT), thermodynamic, and transport properties of isobutane for process design and operations. Tables are provided for gaseous and liquid isobutane at temperatures between 135 and 600K at pressures to 35 MPa. These tables apply directly only to pure gaseous and liquid isobutane. However, it is expected that mathematical models and tables shall be useful for the thermophysical properties of mixtures containing isobutane, such as natural gas. These thermophysical property tables are: Thermophysical Properties of Coexisting Gaseous and Liquid Isobutane, in SI units and Thermophysical Properties of Isobutane, along isobars, in SI units.

1.1 The thermophysical property tables for isobutane are for use in the calculation of the pressure-volume-temperature (PVT), thermodynamic, and transport properties of isobutane for process design and operations. Two tables provide properties at the conditions of liquid-vapor equilibrium (saturation properties), one for liquid and one for vapor, at temperatures between 120 K and the critical point, 407.81 K. A third table provides properties at selected T, p points for the equilibrium phase at temperatures between 120 K and 570 K at pressures to 20 MPa. The tables were developed using the National Institute of Standards and Technology Standard Reference Database product REFPROP, version 9.1.

1.2 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.