Pre-filled disposable syringe has axially-sliding needle hub released by needle-cap removal, and advanced away from seal by initial fluid pressure

摘要

The tubular body (1) is a sealed (10, 15) liquid-filled chamber. A channel (13) can be released, to pass liquid from the chamber and through a further channel in the needle boss (20), to reach the needle. This occurs when the boss is moved between an axially-retracted position, in which the channel (13) is sealed, and an advanced position permitting flow from the chamber to and through the needle (28). A cap (30) covers the base and has a detachment location (35) connecting it to the tubular body. An axial stop (32) holds the boss in the sealing position when it is covered by the cap. A further axial stop (23) limits advancement of the hub, following cap removal.