The sorption pump is an oil-free #prevacuum pump that is based on the adsorption of gases on cold surfaces. The colder the surface, the more efficient the pumping is! Therefore liquid nitrogen with a temperature less than 77 degrees Kelvin is used for cooling the adsorber. The adsorber is a porous zeolite with a very large surface area as the pores have a diameter in the range of a few nanometers (or less). If the pump is full, then it needs to be renewed by degassing, which is basically heating the adsorber so that the gas can remove the pump through the outlet.