A venting device is presented. The venting device comprises a venting member made from a hydrophobic and gas-permeable material. The venting member has an environment coupling surface and an opposed cartridge coupling surface and a carrier member. The carrier member structurally supports the venting member. The venting member is designed such that the venting device and a liquid drug cartridge form, in the assembled state, a compact common cartridge assembly. After inserting the cartridge assembly into a cartridge compartment of an ambulatory infusion device, the cartridge coupling surface fluidic couples, to a non liquid contacting outer surface of the movable wall, and the environment coupling surface at the same time fluidic couples to the environment.
