Abstract: Continuous extraction units are constructed having a plurality of extraction chambers containing extractable material. Without disruption of total fluid flow in the unit: an extraction chamber completely depleted of extract can be evacuated of solvent and replaced with an extraction chamber containing fresh extractable material. The extract is continuously separated from the solvent in an expansion chamber where it is continuously or periodically removed from the unit. All solvent can be retained within the unit. One or more compressors can be used to circulate the fluid through the extraction chambers, the expansion chamber, and a condenser, where the expansion chamber and the condenser can be coupled as a heat exchanger.