| 摘要 |
A disposable syringe assembly 10 including a cylinder body 12, a needle assembly 14, a piston assembly 16, a rear seal assembly 18, a hollow shaft 20, and a valve assembly having a valve port 61 and valve seals 49. The needle assembly may be releasably engaged with the cylinder body. The body and the piston assembly moveable within the body may define each of a fluid chamber 74 and an annular chamber 28. As fluid is drawn into the fluid chamber by movement of the piston assembly, air may be displaced from the annular chamber through the valve assembly. As fluid is discharged from the fluid chamber, the valve assembly may be closed and a vacuum created in the annular chamber. A valve positioner may control connector connectivity and valve port position. Near the end of the fluid discharge piston stroke, a connector 88 engaged with either the shaft of with the piston assembly may engage selectively engage a mating connector on the needle assembly. The needle assembly may be disengaged from the body. Thereafter, the axial fluid discharging, connecting and disengaging force may be removed and the needle assembly may automatically be retracted into the body to safely conceal the needle therein.
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