Disposable syringe.

摘要

A disposable once only syringe for medical use has a tubular piston 22 connected to a piston rod 10 by a headed projection 18 20 passed through the piston bore, doubled over and then trapped in a recess 40 by a relative reverse movement of the parts. The parts are held together by the trapping of the projection in syringe filling, but upon ejection of contents the piston rod moves relative to the piston for a short distance to free the projection which allows the projection to disengage from the recess and move out of alignment with the recess. Any attempt to refill the syringe by a repeat operation causes the projection to pull through the piston and the piston rod to separate.