A novel apparatus for high-pressure studies of vapor-liquid equilibria in multicomponent fluid systems is fully described. It has been designed to get, almost simultaneously, vapor-liquid equilibrium properties and liquid, vapor, and saturating pressure-volume-temperature properties between 253 and 423 K and from subatmospheric pressures up to 40 MPa. The way of getting data allows quite continuous recording of pressure-density data along isotherms in compressed phases up to the saturation points. Sample results are given to illustrate the procedures, and results on pure refrigerant compounds R-32 and R-218 are discussed. New data on the refrigerant blend R-409A are presented.