Patent ID: 8034024

Claim:
A medical syringe comprising a barrel having a front end and a open rear end, a plunger which is slidable in the barrel, the plunger being under reduced pressure and having an open front which is plugged by a piston, the piston being releasably locked to the front of the plunger, a luer which is in the front end of the barrel and is releasably locked against retraction by a locking means, the luer having a through passageway to allow liquid to be expelled from the syringe, the luer containing a rear portion which is formed with a plurality of circumferential locking ribs, the piston containing a cavity, whereby advancement of the plunger along the barrel causes the rear portion of the luer to enter into the cavity and enables the luer to be locked to the piston by engagement of one or more of the locking ribs with an internal wall of cavity, and wherein the plunger remains stationary relative to the barrel during retraction of the piston once the piston has been unlocked from the front of the plunger.