Abstract: A syringe (10) comprises a barrel (12) having an open first end (16) and a second end (18) having an opening (20) for passage of fluid therethrough. Furthermore, the syringe comprises a plunger (14) adapted to be slidably received in the first end and which has a shaft (24), and a head (26) for sliding and sealing engagement with an internal wall of the barrel. In addition, at least one locking member (30) engages the barrel and the shaft, having at least one first tine (32) for selectively engaging the plunger and at least one second tine (34) for selectively engaging an internal wall of the barrel. At least one locking member is adapted to restrict outward movement of the plunger relative to the barrel, but has sufficient flexibility to allow limited outward movement of the plunger relative to the barrel, subsequent to inward movement of the plunger following outward movement of the plunger relative to the barrel.

Abstract: Syringe having a plunger, a barrel and a restrictor mechanism between the shaft of the plunger and the barrel and including a first part engaged with the barrel for limiting movement of the first part with respect to the barrel in a first direction, and a second part. The restrictor mechanism and/or plunger shaft carries a formation for limiting movement of the restrictor mechanism with respect to the plunger in the first direction. The restrictor mechanism as a further member which restricts movement of the restrictor mechanism with respect to the barrel or plunger shaft in a second direction. A latch member prevents he further member from restricting movement of the restrictor mechanism with respect to the barrel or plunger shaft in the second direction until a predetermined point in an operation cycle of the syringe.

Abstract: A disposable syringe (2) is disclosed. Withdrawal of a plunger handle (18) in the direction of arrow B to fill the syringe causes a moveable safety bobbin (20) to lock, and shaft (16) slides in the direction of arrow B relative to safety bobbin (20) and washer (22). Subsequent depression of plunger handle (18) in the direction of arrow A causes safety bobbin (20) to move along barrel (4), from which position it can not be withdrawn. This therefore prevents subsequent withdrawal of piston (14) and therefore prevents re-use of the syringe.