Why does a NOx container get cold when NOx is released? and What is the relationship of the vapor pressure curve with the liquid-vapor dome?
The vapor pressure curve describes the relationship between temperature and pressure for which the pure substance can exist as liquid and vapor, together in equilibrium.  So it is not necessarily all liquid or all vapor.  Both can be present in different proportions.  As far as specific volume is concerned, your tables should list both the vapor specific volume and the liquid  specific volume.  The specific volume of the combination of vapor and liquid is proportional to the mass fraction of each.  (So you need to know the mass fractions of vapor and liquid).