Dryer unit for compressed air and other gaseous media

A vertically directed dryer unit (10) for compressed air, comprising a dryer cartridge (22) which, together with a housing (16, 18, 20), defines an inlet head area (92) and an outlet head area (72). A plurality of hollow membrane fibers (30) extend inside the cartridge between the two head areas, the wall material thereof being more permeable with respect to water vapor than air. An outlet valve (90) is provided between the outlet head area (72) and an outlet (74) of the drier unit. Said valve only opens when the pressure in the outlet head area (72) produces sufficient pressure for the provision of purging air. The purging air is fed to the outer surface of the membrane fibers (30) via a throttle element (70).