A stopper for fluid coupling of a valve of a pressurized fluid cylinder, the valve comprising a filling connector for filling with and withdrawing fluid, the stopper comprising:
- a self-locking sheath configured to slip onto the filling connector, the self-locking sheath extending about a central longitudinal axis, the self-locking sheath comprising, on an inner surface and at a first end, a tapped portion designed to engage with a threaded portion formed on an outer surface of the filling connector, wherein the tapped portion comprises at least one recess parallel to the central longitudinal axis in projection according to a plane perpendicular to the central longitudinal axis, the at least one recess being secant with a circle of smaller diameter of the tapped portion, and in that an inner surface of the self-locking sheath comprises, at a second end opposite the first end, a sealing spindle extending inside the self-locking sheath in a direction parallel to the central longitudinal axis towards the second end of the self-locking sheath as far as a free end located between the first and second ends of the self-locking sheath, the free end of the sealing spindle configured to form a protective cover for a surface of the filling connector designed to engage with a filling tool, the free end of the sealing spindle comprising a sealing member designed to press against a surface of the filling connector in order to create a seal, the sealing member of the free end of the sealing spindle comprising an O-ring housed in a circular groove formed on the free end of the sealing spindle,
- wherein the self-locking sheath comprises an open-work body having at least one opening, the stopper comprising a tamper-evident seal distinct from the self-locking sheath, the tamper-evident seal being designed to be interposed between the filling connector and the self-locking sheath, the tamper-evident seal comprising at least one flexible frangible tab, and in an assembled position, the at least one tab being deployed and projecting into the at least one opening of the self-locking sheath and acting as a stop preventing the self-locking sheath from rotating, the tab being able to be moved mechanically and elastically into a retracted position inside the self-locking sheath in order to selectively suppress the rotation-preventing stop,
- wherein the at least one opening is transverse to the central longitudinal axis thereby allowing access by the flexible frangible tab,
- wherein in the deployed position, the flexible frangible tabs project through the at least one opening, and
- wherein the flexible frangible tabs may be manually pushed into the at least one opening.