Liquid purification or separation – Filter – Prefilt flow distributor or diverter
Reexamination Certificate
1999-12-22
2001-10-02
Kim, John (Department: 1723)
Liquid purification or separation
Filter
Prefilt flow distributor or diverter
C210S232000, C210S473000
Reexamination Certificate
active
06296126
ABSTRACT:
CROSS-REFERENCE TO RELATED APPLICATION
This application corresponds to German Patent Application Serial No. 198 59 693.6 filed on Dec. 23, 1998. The contents thereof are incorporated herein.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to a device for removing a wetting liquid from one or more capillaries. The purpose of the invention is to simplify the removal of a liquid from capillaries or to enable the liquid to be obtained as a free-flowing liquid.
2. Description of Related Art
Capillaries are narrow spatial structures in which surface effects of liquids occur. They can have any cross-sectional shape, including tubes and gaps. The dimensions of the cross section are in the millimeter to sub-micron region in at least one direction. The capillaries can have any desired spatial course.
Capillaries can exist as discrete structures in the form of individual straight or bent tubes having a relatively thin wall, or they can be in the form of a tube passing through a body. Furthermore, they can be pores in an open-pore porous body or sintered body or in the form of spaces between closely packed fibers in the form of paper, nonwovens or felt. They can furthermore have the shape of narrow gaps.
The surface of a wetting liquid adjoining a solid wall forms a contact angle from zero degrees to less than ninety degrees with the wall. In other words, wetting liquids have a contact angle which is greater than zero. Owing to their surface tension, wetting liquids are drawn into capillaries until the latter are completely filled. If a small force acts on the liquid at the exit end of the capillaries, the surface tension can hold the liquid in the capillaries and prevent it from exiting. The liquid can be forced to exit from the end of the capillaries by a sufficiently large pressure difference in the liquid between the capillary entrance and the capillary exit.
European Patent No. 336,483 discloses a device for separating an initially introduced liquid. The device consists of a first open-pore membrane (separator membrane) and a second open-pore membrane (collector membrane). The collector membrane is directly adjacent to the side of the separator membrane. The part of the liquid introduced on the one side of the separator membrane and which has passed through the separator membrane enters the collector membrane where it remains. The liquid collected in the collector membrane below the separator membrane can be reacted with a reagent applied to the collector membrane or the collected liquid can be washed out of the collector membrane by a further liquid and subsequently analyzed. The liquid separated therefrom by the separator membrane and collected in the collector membrane can thus remain in the collector membrane during its further analysis or it can be washed out, in which case it is mixed with a further liquid. In either case, there is not obtained a free-flowing liquid that consists of only the part of the initially introduced liquid which has been separated therefrom by the separator membrane.
For the analysis or use of liquids which have been collected with the aid of capillaries or separated from a liquid medium, it may be advantageous or necessary to obtain the liquid from the capillaries as a free-flowing liquid which is not mixed with any further liquid.
BRIEF SUMMARY OF THE INVENTION
A primary object of the invention is to provide a device by which the liquid can be removed from one or more capillaries and collected in a collecting chamber as a free-flowing liquid. In a sufficiently large collecting chamber, surface effects are virtually no longer effective.
This object is achieved in accordance with the invention by a device having the following characterizing features:
in each case, a wedge-shaped cut-out in a body at the exit end into which at least one capillary runs;
a radius of curvature of the wedge edge of the cut-out which radius is smaller than half the smallest dimension of the largest capillary which runs into the wedge-shaped cut-out; and
a wedge angle of less than 150 degrees between the wedge surfaces of the cut-out in the vicinity of the wedge edge;
wherein the collecting chamber is adjacent to the base side of the wedge-shaped cut-out.
The wedge-shaped cut-out has a wedge edge and a base side. The radius of curvature of the wedge edge is smaller than the radius of curvature of a capillary having a circular cross section. In the case of capillaries having any desired cross section but with dimensions that are in the same order of magnitude in two mutually perpendicular directions, the radius of curvature of the wedge edge is smaller than the equivalent radius of the noncircular capillary. The equivalent radius of a capillary having a noncircular cross section is the radius of a circle whose area is identical to the area of the noncircular cross section of the capillary. In the case of capillaries which are in the form of pores in an open-pore body, the cross-sectional area of the capillaries is distributed over the region of the cross section. In this case, the radius of curvature of the wedge edge is smaller than half the smallest dimension of the capillary having the largest cross section. In the case of slot-shaped capillaries, the radius of curvature of the wedge edge is smaller than half the thickness of the slot.
The wedge edge is adjacent to the two wedge surfaces of the cut-out. These two wedge surfaces form a wedge angle of less than 150 degrees, preferably less than ninety degrees, with one another. The wedge surfaces of the cut-out can be rounded off in a convex manner in the region of the base side.
The device according to the invention can be in the form of a one-piece body or can be composed of two parts. In the two-piece device, at least one capillary is located in the first body. The second body consists of a base plate which is provided on one side with preferably a plurality of projections. At least one wedge-shaped cut-out is present in at least one of these projections. A projection can be provided with a plurality of wedge-shaped cut-outs, each of which is assigned to at least one capillary. The free end of at least one projection is in contact with the surface of the first body, in which the exit end of at least one capillary is located. The beginning of the wedge edge of the wedge-shaped cut-out is inside the exit area of the capillary. Any small separation which may be present between the first body and the free end of the projections of the second body has no effect on the action of the device according to the invention as long as the liquid present at the exit ends of the capillaries in the first body is in contact with the free end of a projection of the second body.
Furthermore, a collecting chamber is provided in the vicinity of the wedge-shaped cut-outs provided in the projections. This collecting chamber is essentially limited by the side of the base plate on which the projections are provided and by the side of the first body in which the exit areas of the capillaries are located.
In the two-piece device, the first body can contain a single capillary or a plurality of individual capillaries. The second body can furthermore be an open-pore membrane or an open-pore sintered body, or it can consist of fibers, such as nonwoven, felt or paper, for example blotting paper. Bodies of this type preferably have a planar exit side. In the latter case, it is sufficient to bring the free ends of projections containing at least one wedge-shaped cut-out into contact with the exit side of the open pores in the first body. Owing to the multiplicity of randomly distributed pores which are generally interconnected within a body of this type, the position of the beginning of the wedge edge at the free end of the projections can be selected virtually freely as long as a sufficiently large number of wedge-shaped cutouts is present.
In the two-piece device according to the invention, the wedge edge of the wedge-shaped cut-outs, which are present in the projections on one side of the second body, can be perpendicular to t
Kim John
Microparts Gesellschaft
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
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