The permeation rates of water vapor, CO2, and oxygen contained in the air stream are faster than nitrogen and argon and will rapidly diffuse through the fiber walls. The slower diffused nitrogen molecules remain in the fiber bore and are collected as the nitrogen product gas. The air flow rate will determine how much undiffused oxygen remains with the nitrogen gas. The nitrogen product gas is extremely dry, with atmospheric dew points typically below -40°F. The membranes act like a filter with no moving parts and continuously generate nitrogen at selected flow and purity.