Liquid purification or separation – Processes – Separating
Reexamination Certificate
1999-12-20
2001-08-14
Kim, John (Department: 1723)
Liquid purification or separation
Processes
Separating
C210S188000, C210S435000, C210S436000, C210S446000, C210S456000, C210S472000, C210S483000, C210S488000
Reexamination Certificate
active
06274055
ABSTRACT:
FIELD OF INVENTION
This invention relates generally to liquid filtration devices. More particularly, this invention relates to an in-line gravity driven liquid filtration device usable to filter blood, blood products and to remove chemical agents used to disinfect or otherwise treat blood or blood products.
BACKGROUND OF THE INVENTION
Typically, gravity feed blood filtration devices require user manipulation of vent filters during the filtration process. The manipulation of the vent filters must occur at the proper time during the filtration process or the system will not filter properly and blood being filtered may be rendered unusable. Since, user manipulation of vent filters is time consuming and costly, it is desirable to achieve a liquid filtration device which may filter blood without the manipulation of vent filters or filtration devices. Moreover, blood filtration devices usually allow liquid to remain within the filtration device after filtration has occurred. This remaining liquid, referred to as a hold up volume, is often greater than the desired maximum amount. Also, blood filtration devices allow an undesirably high amount of air that is purged therefrom to be left in the receiving blood bag.
The filtration device disclosed in U.S. Ser. No. 08/209,523, and entitled “A Filtration Device Usable for Removal of Leukocytes and Other Blood Components” filed Mar. 10, 1994, which is hereby incorporated by reference and made a part of the disclosure herein, overcomes the aforementioned vent filter manipulation problem. However, it is desirable to reduce the hold up volume of this device and to reduce the manufacturing cost thereof, while maintaining an acceptable total filtration time. It is also desirable to achieve a filtration device which does not require draining of the outlet tubing at the end of the filtration cycle.
Blood filtration devices typically do not have features which prevent the tubing attached thereto from becoming kinked. It is, therefore, desirable to achieve a liquid filtration device which filters blood without the manipulation of vent filters, minimizes hold up volume, that minimizes the volume of air that is added to the receiving blood bag, that reduces manufacturing cost and also reduces the possibility of kinked tubing when the device is assembled into a filtration system and packaged for shipping.
SUMMARY OF THE INVENTION
The shortcomings of the prior art may be alleviated using a filtration device constructed in accordance with the principles of the present invention. The filtration device of the present invention is capable of filtering blood to remove leukocytes, other blood components and chemical agents which may be used to treat the blood. The filtration device includes a first chamber capable of collecting and directing the flow of unfiltered liquid therein and a second chamber in fluid flow relationship with the first chamber capable of collecting and directing the flow of filtered liquid.
In one aspect of the invention, the in-line liquid filtration device comprises a housing having an inlet port and an outlet port therein, a filter element disposed within the housing between the inlet port and outlet port so as to filter the liquid which flows into the filtration device via the inlet port, and means within the filtration device, for allowing gases such as air to vent from filtration device through the outlet port during filtration. Between the inlet port and outlet port, the filter elements divide the housing into a first chamber and a second chamber. The filtration device may be sized so that the distance between a filter element and the inlet port prevents the accumulation of gases in the first chamber. Similarly, the liquid filtration device may be sized so that the distance between the at least one filter element and the outlet port forces gases within the second chamber to enter the outlet port during filtration.
In another aspect of the invention, the means, disposed within the device, for allowing gases to vent through the filtration device through the outlet port during filtration comprises a flow deflector disposed within the second chamber between the filter element and the outlet port. The flow deflector may comprise a relatively flat member such as a disk, and the disk may comprise at least one radially extending rib. The filtration device may comprise more than one filter element and a seal ring may be mounted between two of the filter elements. The inlet port and outlet port of the filtration device may be coaxially oriented. The housing may comprise an inlet section and an outlet section attached to the inlet section. The inlet port may be disposed within the inlet section and the outlet port may be disposed within the outlet section. The filter element may be sealed between the inlet section and either the outlet section or a seal ring. If the device contains a plurality of filter elements therein, the filter elements may be stacked on top of one another and separated about their periphery by seal rings.
In another aspect of the invention, the means, disposed within the filtration device, for allowing gases to vent from filtration device through the outlet port during filtration may comprises a flow deflector disposed within the first chamber between the filter element and the inlet port. The flow deflector may comprise a flat member such as a disk and the disk may be suspended within the first chamber.
In yet another aspect of the invention, the aforementioned means may comprise a channel disposed below the filter element in the second chamber, the channel being adapted to allow fluid to flow to the outlet port from the filter element. The channel may comprise a substantially spiral channel. The filter element may cover the channel to allow liquid filtered within the filter element to flow directly into the channel.
The aforementioned means may further comprise a second channel, the second channel being disposed within the first chamber and adapted to allow fluid to flow from the inlet port to the filter element. The second channel may cover the filter element wherein liquid within the second channel flows directly into the filter element. The second channel may comprise a spiral channel leading from an outer periphery of the first chamber to a central location within the first chamber. The second channel may also comprise a modified spiral channel. The filtration device may also comprise means for supporting the filter element within the filtration device. This means may comprise a screen or a molded part.
The filtration device may also comprise a third channel extending radially between the inlet port and the second channel. The inlet port may be located about a periphery of the housing and a second channel extending from the periphery of the first chamber within the housing to a central location within the first chamber. The inlet port may be adapted to receive flexible tubing therein and may include a tapered hole. The filtration device may also include a tube guide on the housing adapted to guide a flexible tube into the inlet port. The tube guide may also comprise a substantially right angle support member. At least one protruding rib may extend from an inside diameter of the tapered hole.
The device may also include a second outlet port being positioned within the housing at a location below the filter element to allow air within the housing to flow therethrough. The second outlet port may have a hydrophilic filter disposed to allow air to pass therethrough without allowing certain liquids to flow therethrough.
The filtration device may further comprise an in-line vent in fluid flow relationship with the outlet port. The in-line vent being adapted with a hydrophilic filter therein, an inlet, a first outlet and a second outlet. The hydrophilic filter may be located between the inlet and the first outlet and adapted to allow air to pass therethrough without allowing filtered liquid to pass therethrough.
REFERENCES:
patent: 2073991 (1937-03-01), Koser
patent: 2665009 (1954-01-01), Harstick
patent: 2784843 (1957
Hemasure Inc.
Heslin & Rothenberg, P.C.
Kim John
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