Centrifugal filtering device and filter unit therefor

A centrifugal filtering device, comprising:

• (a) a generally cylindrical sample tube having an open inlet end and an open outlet end with a central circular opening for egress of fluid from the sample tube and a forwardly-facing annular surface surrounding said central opening;
• (b) a filter support element ultrasonically welded to the outlet end of the sample tube at an annular joint and defining an open-ended passage coaxial with the sample tube, said support element having a forward end formed with an annular seat surrounding said passage and a rearward end with a rearwardly-facing annular surface surrounding said passage and dimensioned and positioned for register with said forwardly-facing annular surface of the sample tube;
• (c) a circular filter having a periphery engaged by and compressed between said forwardly-facing annular surface of said sample tube and said rearwardly-facing annular surface of said support element for completely occluding said passage such that liquid can enter said passage from said sample tube only by passing through said filter;
• (d) a receiver vessel having an open inlet end removably mounted on said seat, and a closed outer end, for collecting and retaining liquid advancing forwardly through said passage from said filter;
• and
• (e) a cap for closing the inlet end of said sample tube;
• (f) said annular joint essentially concentrically surrounding said filter periphery in outwardly spaced relation thereto.

A centrifugal filtering device, comprising:

• (a) a generally cylindrical sample tube made of polypropylene and having an open inlet end and an open outlet end;
• (b) a filter support element made of polypropylene ultrasonically welded to the outlet end of the sample tube at an annular joint and defining an open-ended passage coaxial with the sample tube, said support element having a forward end formed with an annular seat surrounding said passage;
• (c) a filter clamped between the outlet end of the sample tube and the support element for completely occluding said passage such that liquid can enter said passage from said sample tube only by passing through said filter;
• (d) a receiver vessel made of polypropylene, having an open inlet end removably mounted on said seat, and a closed outer end, for collecting and retaining liquid advancing forwardly through said passage from said filter;
• and
• (e) a cap for closing the inlet end of said sample tube.

A centrifugal filtering device comprising:

• (a) a generally cylindrical sample tube having an open inlet end and an open outlet end;
• (b) a filter support element ultrasonically welded to the outlet end of the sample tube at an annular joint and defining an open-ended passage coaxial with the sample tube, said support element having a forward end formed with an annular seat surrounding said passage;
• (c) a filter clamped between the outlet end of the sample tube and the support element for completely occluding said passage such that liquid can enter said passage from said sample tube only by passing through said filter;
• (d) a receiver vessel having an open inlet end removably mounted on said seat, and a closed outer end, for collecting and retaining liquid advancing forwardly through said passage from said filter;
• and
• (e) a cap for closing the inlet end of said sample tube;
• (f) said sample tube having a generally cylindrical inner wall defining a chamber for receiving a fluid sample, and a circular outlet opening for said chamber at the outlet end of said tube, the forward portion of said inner wall tapering inwardly to the periphery of said outlet opening.

A centrifugal filtering device, comprising:

• (a) a generally cylindrical sample tube having an open inlet end and an open outlet end;
• (b) a filter support element ultrasonically welded to the outlet end of the sample tube at an annular joint and defining an open-ended passage coaxial with the sample tube, said support element having a forward end formed with an annular seat surrounding said passage;
• (c) a filter clamped between the outlet end of the sample tube and the support element for completely occluding said passage such that liquid can enter said passage from said sample tube only by passing through said filter;
• (d) a receiver vessel having an open inlet end removably mounted on said seat, and a closed outer end, for collecting and retaining liquid advancing forwardly through said passage from said filter;
• and
• (e) a cap for closing the inlet end of said sample tube;
• (f) said sample tube having a generally cylindrical inner wall defining a chamber for receiving a fluid sample, and further including a porous retainer disc disposed in said chamber intermediate the inlet and outlet ends of the tube to divide said chamber into rearward and forward compartments, and a packing filling said forward compartment.

In a centrifugal filtering device, a filter unit comprising:

• (a) a generally cylindrical sample tube having an open inlet end and an open outlet end;
• (b) a filter support element ultrasonically welded to the outlet end of the sample tube at an annular joint and defining an open-ended passage coaxial with the sample tube, said support element having a forward end formed with an annular seat surrounding said passage for removably mounting a receiver vessel for collecting and retaining liquid advancing forwardly through said passage;
• and
• (c) a filter clamped between the outlet end of the sample tube and the support element for completely occluding said passage such that liquid can enter said passage from said sample tube only by passing through said filter;
• (d) said annular joint being sufficiently mechanically weaker than said sample tube and said filter support element to enable the sample tube and the support element to be separated by application of manual bending forces at said joint for recovering said filter.

In a centrifugal filtering device, a filter unit comprising:

• (a) a generally cylindrical sample tube having an open inlet end and an open outlet end with a central circular opening for egress of fluid from the sample tube and a forwardly-facing annular surface surrounding said central opening;
• (b) a filter support element ultrasonically welded to the outlet end of the sample tube at an annular joint and defining an open-ended passage coaxial with the sample tube, said support element having a forward end formed with an annular seat surrounding said passage for removably mounting a receiver vessel for collecting and retaining liquid advancing forwardly through said passage, said support element further having a rearward end with a rearwardly-facing annular surface surrounding said passage and dimensioned and positioned for register with said forwardly-facing annular surface of the sample tube;
• and
• (c) a circular filter having a periphery engaged by and compressed between said forwardly-facing annular surface of said sample tube and said rearwardly-facing annular surface of said support element for completely occluding said passage such that liquid can enter said passage from said sample tube only by passing through said filter;
• (d) said annular joint essentially concentrically surrounding said filter periphery in outwardly spaced relation thereto.

In a centrifugal filtering device, a filter unit comprising:

• (a) a generally cylindrical sample tube made of polypropylene and having an open inlet end and an open outlet end;
• (b) a filter support element made of polypropylene ultrasonically welded to the outlet end of the sample tube at an annular joint and defining an open-ended passage coaxial with the sample tube, said support element having a forward end formed with an annular seat surrounding said passage for removably mounting a receiver vessel for collecting and retaining liquid advancing forwardly through said passage;
• and
• (c) a filter clamped between the outlet end of the sample tube and the support element for completely occluding said passage such that liquid can enter said passage from said sample tube only by passing through said filter.

In a centrifugal filtering device, a filter unit comprising:

• (a) a generally cylindrical sample tube having an open inlet end and an open outlet end;
• (b) a filter support element ultrasonically welded to the outlet end of the sample tube at an annular joint and defining an open-ended passage coaxial with the sample tube, said support element having a forward end formed with an annular seat surrounding said passage for removably mounting a receiver vessel for collecting and retaining liquid advancing forwardly through said passage;
• and
• (c) a filter clamped between the outlet end of the sample tube and the support element for completely occluding said passage such that liquid can enter said passage from said sample tube only by passing through said filter;
• (d) said sample tube having a generally cylindrical inner wall defining a chamber for receiving a fluid sample, and a circular outlet opening for said chamber at the outlet end of said tube, the forward portion of said inner wall tapering inwardly to the periphery of said outlet opening.

In a centrifugal filtering device, a filter unit comprising:

• (a) a generally cylindrical sample tube having an open inlet end and an open outlet end;
• (b) a filter support element ultrasonically welded to the outlet end of the sample tube at an annular joint and defining an open-ended passage coaxial with the sample tube, said support element having a forward end formed with an annular seat surrounding said passage for removably mounting a receiver vessel for collecting and retaining liquid advancing forwardly through said passage;
• and
• (c) a filter clamped between the outlet end of the sample tube and the support element for completely occluding said passage such that liquid can enter said passage from said sample tube only by passing through said filter;
• (d) said seat being formed with two portions of respectively different diameters, disposed in succession along the axis of said passage, for respectively mounting receiver vessels of different sizes.