Liquid filtering and dispensing assembly

Claim 1

A portable hand-operated device capable of being manipulated by a hand of a user to dispose a quantity of a liquid therein, which quantity of liquid may contain particles of solid material and have an air bubble situated thereabove, and thereafter discharge a desired metered quantity of said liquid free of air and said particles of foreign material therefrom into a desired container or through a hypodermic needle that includes a head in which a tapered recess is defined, said devices including: a. an elongate cylindrical barrel that has a first end portion on which external threads are defined, and a second end portion that includes an outwardly extending flange that may be engaged by the fore finger and middle finger of said hand; b. a cup that includes a circular web that has an internally threaded cylindrical side wall extending from the periphery thereof, said web including first and second sides; said first side having a plurality of spaced grooves defined therein; said cup including a tapered first protuberance that extends outwardly from said second side, with said first protuberance having a longitudinal first bore therein that is in communication with said grooves, said first protuberance capable of removably and sealingly engaging said tapered recess in said hypodermic needle head to support said hypodermic needle from said cup, and said internally threaded side wall engaging said external threads to removably support said cup on said barrel; c. a flat circular filter assembly that includes a screen that rests on said first side and a filter membrane mounted on said screen, said screen and membrane of such diameters as to extend under said first end portion of said barrel, said screen cooperating with said grooves to define a plurality of passages through which said liquid that has been filtered may flow to said first bore; d. a first resilient sealing ring in said cup that is deformed by pressure contact with the extremity of said first end portion to seal with an outer circumferential portion of said membrane; e. an elongate ram having first and second longitudinally aligned portions that at their junctions define a circular body shoulder, said first portions of such diameter as to slidably engage the interior of said barrel, said first portion having a first free end surface and said second portion a second free end surface, a longitudinal second bore in said ram that extends between said first end and a cavity that extends inwardly in said ram surface from said second free end surface thereof, said body shoulder acting as a stop when it engages the outer extremity of said second portion of said barrel to prevent said first free end surface of said ram pressure contacting said membrane when said ram is moved inwardly in said barrel, and a circumferential groove in said first portion of said ram adjacent said first free end surface thereof; f. a second resilient sealing ring mounted in said groove and in slidable sealing contact with the interior of said barrel, with said second longitudinal bore and cavity allowing air from said air bubble to escape to the ambient atmosphere when said ram is moved towards said cup, and the expulsion of all air from said bubble being signaled when liquid from said barrel starts to discharge into said cavity; g. a plate that may removably overlie said second free end of said ram; and h. first means that project from said plate and removably engage said cavity and seal with the latter after said air from said air bubble has been discharged from liquid in said barrel, with said plate capable of being engaged by the thumb of said hand of said user as said fore finger and middle finger engage said flange to permit said first free end of said ram to be moved towards said cup to force liquid in said barrel through said membrane, with said liquid flowing through said membrane discharging into said passages to flow therefrom into said first longitudinal passage.