| 摘要 |
A safety syringe has a hollow barrel, a seal, a needle hub and a plunger. The plunger is mounted in the hollow barrel and has a needle retractor at one end. The seal has an axial circular through hole that is mounted around the plunger and has multiple detents. The hollow barrel has an inside surface and the seal has an outside surface, which correspond to each other and are non-circular. The plunger has detent protrusions corresponding to the detents in the seal to selectively hold the plunger is position. The needle hub with a needle is detachably mounted inside the hollow barrel and has an axial locking opening to engage the plunger. Since the plunger will not accidentally rotate, the protruding head on the plunger can be inserted precisely into the locking chamber of the needle hub and either engage or be withdrawn from the axial locking opening.
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