The system operates on the basis of different gas permeation rates through a polymer membrane under a difference in partial pressure across the membrane. As the gas passes through the membrane, fast-permeating components permeate through the dense selective membrane layer into the shell-side space and are discharged to the atmosphere.

Slow-permeating components travel along the full length of the membrane and are then supplied to the user.

The driving force is the difference in partial pressure on the two sides of the membrane. The low-permeability component can be enriched relative to its initial concentration; however, the higher the concentration, the lower the capacity.

The plants use a pressure-driven compressor process: the mixture is fed to the separation stage under pressure, using compressor equipment for preliminary compression. The separation process is controlled by regulating the pressure and flow rate of the gas mixtures.