Power operated syringe holding device for filtering a liquid

Claim 1

In combination with a syringe that includes a cylindrical shell that has a first externally beaded end and a second apertured end, a plunger slidably and sealingly mounted in said shell and projecting from said first end thereof, a quantity of liquid to be filtered disposed inside said shell between said plunger and said second end, a filter assembly having first and second apertured ends, said first end of said assembly removably and sealingly engaging said second end of said syringe, and a sterile container for receiving filtered liquid from said second end of said filter assembly, a device operated by pressurized air from a source therof for moving said plunger towards said second end to force said liquid in said shell through said filter assembly into said sterile container in a filtered condition, said device including: a. a rigid vertical upright having a first upper end and a lower second end, a first longitudinal bore that extends downwardly in said upright from said first end to intersect a longitudinal counterbore in said upright therebelow of smaller transverse cross section and defining a first body shoulder at the junction therewith, said counterbore at a lower end thereof defining a second body shoulder at a junction with a longitudinal air vent passage that extends to said second end, said first bore having threads on the upper portion thereof; b. first means in engagement with said second end of said upright for maintaining said upright in a vertical position; c. a rigid head supported from said first end of said upright, said head including first and second opposite and outwardly extending portions, said first portion being recessed to removably engage said beaded end of said shell to removably support said syringe in a depending position from said first portion of said head; d. second means for exerting a downward force on said plunger when said syringe is supported from said first head portion, said second means including a horizontal rigid arm that can contact an upper end of said plunger, a rod extending downwardly from said arm, and a piston slidably and sealingly mounted in said first bore and rigidly secured to said rod, said piston having a first upper and a second lower end; e. a ring-shaped plug that has external threads on a first upper portion thereof that engage said threads in said first bore, with said plug including a lower external portion that sealingly engages a part of the surface of said uprIght defining said first bore, said plug including an interior cylindrical surface that slidably and sealingly engages said rod, and said plug including a first upper and lower second end; f. spring means that at all times tend to move said piston, rod and arm upwardly relative to said upright; g. a first stop that projects downwardly from said second end of said plug to contact said first end of said piston, with said first end of said piston, said second end of said plug and a portion of the surface of said upright that defines said first bore cooperating with said first end of said piston and said rod to define an annulus-shaped space that is at all times in communication with a longituidnal air passage in said second head portion, and said air passage in communication with a transverse, axially aligned first bore and counterbore in said second head portion that at their junction define a valve seat, said first bore in said second head portion having threads formed in an outer portion thereof; h. third means for supplying pressurized air to said counterbore in said second head portion; and i. first and second independently operable valve means, with said first valve means including an externally threaded portion that engages said threads in said first bore in said second head portion, said first valve means when in a first position sealing with said first valve seat to obstruct communication between said counterbore in said head and said air passage, said first valve means when in a second position establishing communication between said counterbore in said head and said air passage to permit pressurized air to flow to said annulusshaped space to force said piston, rod and arm downwardly to exert a downward force on said plunger, with said first valve means being placed in said first position after said arm has been forced downwardly to a desired extent, said second valve means when in a first position obstructing communication between said air passage and counterbore in said head and the ambient atmosphere, and said second valve means when in a second position and said valve means in said first position establishing communication between said air passage and the ambient atmosphere for said spring means to move said piston upwardly in said bore in said upright until said piston contacts said first stop.