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Membranes can be used to separate many gas mixtures. Membranes separate gases by allowing some gases to pass through more easily than others. A difference in the partial pressures of the gases on the two sides of the membrane provide the driving force for the tranport of gases through the membrane and the separation to occur. The partial pressure difference may be created by: applying vacuum to one side of the membrane, increasing the pressure of the feed gas above atmospheric, sweeping one side of the membrane with a gas other than the one to be removed, or a combination of these.
CMS gas separation membranes are made of glassy highly fluorinated polymers. They work by molecular sieving. Smaller molecules pass through the membrane more rapidly than larger molecules. For example, oxygen passes through more rapidly than nitrogen. In particular, organic chemicals pass through very slowly compared to oxygen or nitrogen. This mechanism differs from that of rubbery membrane materials like silicone rubber. With rubbery membranes, in addition to molecular volume, the solubility of the gas in the polymer plays a significant role in determining its transport rate. Hydrocarbon vapors tend to have good solubility in silicone rubber membranes and exhibit greater transport rates than nitrogen or oxygen. Which type of membrane is more appropriate to an application is dependent on the operating conditions and the separation that is required. Other factors to consider are the membrane's resistance to fouling and chemical resistance. CMS fluoropolymer membranes resist fouling and are compatible with a wide range of chemicals.
To learn more about our membranes for Nitrogen Enriched Air and VOC/Air Separations visit our
products page.
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