Abstract: The present disclosure relates to a sealing unit (8, 8', 108) for sealing an opening in a wall of a container for storing, transporting, and serving a liquid, for instance a beverage, the sealing unit (8, 8', 108) comprising: - an outer housing and an inner housing (20,40) defining a gas flow passage (38') arranged between an outer surface of the inner housing and an inner surface of the outer housing. The inner housing (20) is movable in axial direction between a first axial position wherein the gas flow passage (38') is closed and gas is prevented from flowing into the container or out of the container and a second axial position wherein the gas flow passage (38') is open and gas is allowed to flow in a generally axial direction (PA1) into the container or out of the container, further comprising a biasing element arranged between the outer housing (20) and inner housing (40) and configured to urge the movable inner housing (20) to move to the first axial position.