A device for sealing a vessel, in particular a cartridge (7) or a test tube for accommodating a freeze dried pharmaceutical product (S), wherein the vessel (1) comprises at its opening end (3) an opening edge (4) and an adjoining longitudinal portion (5) with an evenly formed inner cross section including a front plunger (2) to be positioned inside the vessel (1) at the longitudinal portion (5) is characterized in that the front plunger (2) is configured to be positioned in the vessel (1) in a sealing state in which the front plunger (2) is fully inserted in the vessel (1) or in an exchange state in which the front plunger (2) is inserted partly in the vessel (1) and partly protrudes over the opening edge (4) of the vessel (1) wherein the front plunger (2) comprises sealing means that are configured to seal the inside of the vessel (1) against the outside when the front plunger (2) is positioned in the sealing state and one or more communicating grooves (2i) that are configured to place the inside and outside of the vessel (1) in communication with each other when the front plunger (2) is positioned in the exchange state. Furthermore a method of manufacturing a sealed vessel (1) is disclosed.
