Medical administering needle assembly with filter means

Claim 1

A medical administering needle assembly having longitudinally aligned formost and rearmost ends as regards the direction in which a fluid is to be forced to flow through the assembly when the assembly is in use, comprising: a generally tubular body portion which is formed with a longitudinal passageway having an axis therethrough and open at the rearmost end of the body portion and which has a front end wall formed with an opening at the foremost end of the passageway, the front end wall having at the foremost end of the passageway an annular inner face having an outer circumferential end at the foremost end of the inner peripheral surface of the body portion and an inner circumferential end circumscribing the rearmost end of said opening, said end wall being further formed with a plurality of projections protruding rearwardly from said annular inner face and spaced apart from each another about said axis of the passageway in the body portion, said projections having respective rear end faces in a common plane substantially perpendicular to said axis; a tip portion forwardly projecting from said front end wall and formed with a longitudinal passageway rearwardly merging with said opening and communicating with the passageway in the body portion through the opening; a first disc-shaped filter element located within the passageway in the body portion and having a front end face in contact with said rear end faces of said projections; and a second disc-shaped filter element located within the passageway in said body portion rearwardly of said first filter element and having a front end face in contact over substantially its entire area with the rear end face of said first filter element, each of the first and second filter elements having its outer peripheral surface closely received on the inner peripheral surface of said body portion and being formed with a multiplicity of voids, the first filter element being denser than the second filter element and the voids in the first filter element being smaller in size than the voids in the second filter element.