A volumetric displacement preservation system (10, 100) for conserving a volume of fluid substance (202) in an open internal volume of a container (200), according to which the volumetric displacement conservation system (10, 100) comprises : a fluid exchange structure (12) with a plug (16, 102) to create a sealing coupling with the container (200)； a fluid escape passage (24, 104) in the fluid exchange structure (12) with a first end to be in fluidic communication with the open internal volume of the container (200) and a second end to be in external fluidic communication with the container (200) if the cap (16, 102) is coupled with the container (200), in which the fluid outlet passage (24, 104) has an open condition, in which the fluid can pass through the fluid outlet passage (24, 104), and a closed condition, in which the fluid cannot substantially pass through the fluid outlet passage (24, 104)； a fluid inlet passage (26, 106) in the fluid exchange structure (12) with a first end to be in direct fluidic communication with the open internal volume of the container (200) and a second end to be being in external fluidic communication with the container (200) when the cap (16, 102) is coupled with the container (200) in which the fluid inlet passage (26, 106) has an open condition, in which the fluid can pass through the fluid inlet passage (26, 106), and a closed condition, in which the fluid cannot substantially pass through the passage (26, 106)； fluid inlet； characterized in that a chamber (14, 110) comprises an expandable and compressible air chamber with an internal volume to retain a volume of preservative gas and an orifice (55) for distributing the conservation gas from the chamber (14, 110)； and a fluidic connection for fluidly connecting the hole (55) of the chamber (14, 110) with the second end of the fluid inlet passage (26, 106), so that the chamber (14, 110) is retained in the outside the open internal volume of the container (200)； whereby, if the
