Laboratory intake filter

Claim 1

A filter device comprising a filter element in the form of an elongated body completely formed of a porous plastic material, said elongated body being defined by wall means and first and second ends, said elongated body having a central axial cavity, circular in cross-sections throughout its length, formed therein which is open at said first end and closed by said second end, said cavity extending axially within said elongated body parallel with said wall means, said wall means being stepped so that the diameters of circular cross-sections taken at the region of the cavity near said closed end are smaller than diameters of circular cross-sections taken at the region of the cavity near said open end, said stepped wall means forming a circumferential shoulder within said elongated body against which a tubular insert can rest, a tubular insert defining a central passageway communicating with said cavity so as to allow fluid flow from said cavity through said passageway, said insert when inserted into said cavity being capable of resting on said shoulder and being capable of contacting the inside area of said wall means extending from said shoulder to said first end, said tubular insert providing a means for anchoring the filter device in a liquid reagent supply reservoir and preventing filtration through the volume of the porous plastic material of said elongated body extending from said first end to said circumferential shoulder.