Air Liquide Advanced Separations’ (ALaS) hollow fiber membranes offer the most robust solution for hydrogen purification needs. ALaS membranes operate on the basis of selective permeation. Each membrane is composed of millions of polymeric hollow fibers similar in size to the diameter of a human hair. The “fast gases,” or gases with a higher permeation rate, permeate through the membrane into the hollow interior and are channeled into the permeate stream. Simultaneously, the “slower gases” flow around the fibers and into the residue stream. As a result, the fibers have the ability to selectively separate a fast gas like hydrogen from carbon monoxide, methane, heavier hydrocarbons and other slower gases.