Cloud-point data to 280 degrees C and 2800 bar are reported for a binary mixture of poly(tetrafluoroethylene-co-19.3 mol % hexafluoropropylene) (FEP19) in fluoroform (CHF3) and for ternary mixtures of FEP19CHF3-sulfur hexafluoride (SF6) and FEP19-CO2-SF6. FEP19 does not dissolve in CHF3 at a temperatures less than 235 degrees C due to strong dipolar CHF3-CHF3 interactions relative to FEP19-CHF3 cross interactions. However, FEP19 dissolves in CO2 if the temperature is greater than approximate to 185 degrees C and the pressure is in excess of 1000 bar. When SF6 is added to either FEP19-CO2 or FEP19-CHF3 mixtures, the cloud-point curve is shifted to lower pressures and temperatures due to the increase in favorable dispersion interactions with nonpolar FEP19. The magnitude of the shift in cloud-point pressure per amount of SF6 added to solution decreases in a nonlinear manner with increasing amounts of SF6. The Sanchez-Lacombe equation of state can model the binary FEP19-SCF data if the FEP19-CO2 and FEP19-CHF3 binary interaction parameters are allowed to vary with temperature. However, a poor representation is obtained for the ternary phase behavior.