Separation Media
Thinner membrane, more flow, identical selectivity. Throughput is cheap to buy; purity is the part that costs.
— m³/h
Volumetric throughput across the whole membrane area
Purity here is the limiting case at vanishing stage cut, where the permeate is drawn so slowly that the feed composition never changes — it is the best a single stage can do and real modules operating at useful recovery fall short of it. The calculation also assumes the permeate side is swept to negligible partial pressure; without that the driving force collapses as the permeate accumulates. Concentration polarisation and plasticisation at high pressure both reduce real performance further, and permeability itself is temperature dependent, so quote the temperature with any Barrer figure.
PTFE Membrane Gas Permeation Rate & Enrichment Calculator — free, with the formula and a worked example, at Textile School.