Vacuum pump
MDC vacuum products

Sorption roughing pumps or sorption pumps are used for pumping systems from atmospheric pressure to a pressure of approximately 10-2 Torr. They rely on the dispersion forces existing between a gas and a surface to bind gas molecules on chilled surfaces inside the pump. In other words, they pump by cryosorption.
Sorption pumps typically consist of a cylindrical canister or body that is filled with an adsorbent material. The adsorbent is usually a molecular sieve material, or zeolite, which consists of pellets made of a calcium or a sodium aluminosilicate crystalline matrix. The canister is placed in a dewar cooled by liquid nitrogen. Zeolite is a poor heat conductor, so an array of aluminum fins inside the pump is used to improve thermal contact with the sieve material. The pump body and internal cooling fins are specially designed for maximum heat transfer. The pump neck and flange are made of stainless steel. The pumps are mounted and supported by the flanges and since stainless steel is a poor thermal conductor frosting of adjacent components is minimized. Sorption pumps need liquid nitrogen to operate and, as with any capture pump, they have to be periodically regenerated. Sorption pumps are very clean noncontaminating roughing pumps and are ideal for low throughput applications. They are used in conjunction with getter pumps, ion pumps, or mechanical cryopumps.