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VOLUME [m3/kg, m3/kmol, ft3/lbm, ft3/lbmol] returns the specific volume (inverse density) of a specified substance.  The value and units of the returned value depends on the Unit System setting.  Two arguments are required for all real fluid and ideal gas substances; three are needed for moist air (AIRH2O). Incompressible substances require only one argument (in addition to the name of the substance and that must be temperature.


Note that for substance AirH2O (psychrometrics), the specific volume is defined as the volume of air + water vapor in the air divided by the mass of dry air.


The list of property identifiers needed in the calling arguments and instructions are available in the Thermophysical Function help.




$UnitSystem SI C kPa mass

rho_air=density(Air,T=25 [C],P=101.3 [kPa])

rho_stm=density(Steam,T=100 [C],x=1)


rho_airH2O=density(AirH2O,T=25 [C],P=101.3[kPa], r=0.5)



rho_air=1.184 [kg/m^3]

rho_airH2O=1.165 [kg/m^3]

rho_copper=8,934 [kg/m^3]

rho_stm=0.5975 [kg/m^3]



Thermophysical Functions