Fluid driven dispensing device

摘要

A fluid driven dispensing device (10) in which a piston (14) driven by the fluid discharged from an engine (38) moves a plunger (26) to displace the contents of the syringe. The cross-sectional area of the plunger (26) is greater than the area of the piston (14) exposed to the driving fluid so that a given volume of fluid discharged from the pump will displace a larger volume of beneficial agent from the syringe. Means are also provided for directing fluid discharged from the engine away from the piston to permit on/off operation of the syringe.