Abstract: A single use syringe in the form of a cylindrical barrel with a port end attached to a hypodermic needle. A plunger and piston in the barrel transfer liquid into or from the syringe through a port end. The plunger includes a locking structure formed at a predetermined position. An insert at a remote end of the barrel includes at least one cantilevered, longitudinally extending resilient arm with a radially acting, inwardly extending follower at a free end thereof that rides over the plunger. When the plunger moves to a locking position, the follower engages the plunger locking structure to block any further longitudinal motion of the plunger and piston preventing any subsequent use of the syringe.

Abstract: A single use syringe in the form of a cylindrical barrel with a first end attached to a hypodermic needle. A plunger and piston in the barrel draw liquid into the syringe through the hypodermic needle and eject the liquid through the hypodermic needle. The plunger includes a detent formed at an intermediate location. An insert at the second end of the barrel includes at least one cantilevered, longitudinally extending resilient arm with a follower at a free end thereof that rides over the plunger. When the plunger is pushed to a final position, the follower drops into the plunger detent to block any further longitudinal motion of the plunger and piston preventing any subsequent use.

Abstract: The disposable syringe comprises a cylindrical barrel having a side wall, an axis, and two ends, one of which, the distal end, has an inlet-outlet end for the administration of fluids. A cylindrical plunger is mounted snugly and fluid tight for axial movement within the barrel. An actuating rod has one, distal end connected to the plunger. The barrel at its other, proximal end has means for guiding the actuating rod axially. One or more pins of spring material are within the barrel, one, proximal end imbedded in the barrel side wall, and the other, free distal end located nearer the distal end of the barrel then the location of the proximal end of the pin.