Disposable hypodermic syringe, with a plunger within a hollow cylinder, has an insert for the needle to pass through and hold the needle in the retracted position in the cylinder after use

摘要

The disposable hypodermic syringe has a cylinder (1), a plunger (2), an insert (3) within the cylinder, and a needle cap. The plunger piston (25) can be of rubber. The insert fits within the hollow zone (15) of the cylinder, with a seat (31) of a different outer diameter, a seal (32) and a thin tip (33). The insert has a passage drilling (38) for the needle to pass through. When the plunger is fully depressed it locks with the insert, to carry it back with the needle to the trailing end of the cylinder, when the plunger is snapped off at a nominal fracture point with the needle held within the cylinder and the point is shrouded.