Disposable hypodermic syringe

摘要

A non-reusable syringe comprises a cylinder (a), a plunger (16) moveable within the cylinder to aspirate and eject material and a rotatable plunger rod (6) initially coupled to the plunger. The rotatable plunger rod engages projections on the plunger as it rotates during filling - rotation in the opposite direction during discharge causing the two parts to disengage. The plunger and plunger rod thus uncouple during injection preventing reuse of the syringe. Other forms of the plunger rod are disclosed.