Liquid purification or separation – Processes – Separating
Utility Patent
1999-06-23
2001-01-02
Walker, W. L. (Department: 1723)
Liquid purification or separation
Processes
Separating
C210SDIG009, C210S248000
Utility Patent
active
06168722
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The subject invention relates to fluid filtration devices, and more particularly, to a lenticular filter cartridge assembly housed within a disposable capsule and intended for use in conjunction with a fluid processing system.
2. Background of the Related Art
Cell type filter assemblies, often referred to as lenticular filter assemblies, are well known in the art and have been employed in fluid processing systems for many years. An early example is disclosed in U.S. Pat. No. 2,788,901 to Boeddinghaus et al. Lenticular filter assemblies often include a plurality of vertically oriented coaxially arranged filtration cells disposed within a cylindrical housing. Typically, such a filter housing is formed by structural portions which are secured together by conventional clamping devices that allow for access to the interior of the housing to facilitate filter replacement and maintenance. Examples of prior art filtration cells are disclosed in U.S. Pat. No. 4,783,262 to Ostreicher et al. and U.S. Pat. No. 4,347,208 to Southall.
In known prior art lenticular filtration assemblies, the uppermost and lowermost filtration cells in a filter housing are oftentimes provided with a compressible gasket or O-ring to effect a seal against the housing. See, for example, commonly assigned U.S. Pat. No. 4,704,207 to Chu. In other devices, these cells may be welded to the top and bottom of the cartridge housing to seal process fluids within the system. Additionally, it is known to provide sealing gaskets intermediate adjacent filtration cell layers to effect a seal therebetween, as disclosed in U.S. Pat. No. 4,704,207 to Chu.
During use, process fluid enters the filter housing through an inlet port, passes through the filtration cells, and exits the housing through an outlet port. Over time, the filtration cells will exhibit plugging or the batch will be completed, and the filtration cells are not reused to prevent cross-contamination of process fluids. Thus, to properly maintain the fluid processing system, the structural portions of a conventional filter housing must be separated, the spent filtration cells must be removed, the housing must be thoroughly cleaned to remove contaminants and residues deposited therein, and new filtration cells must be emplaced in the housing, along with any associated sealing gaskets. Such a maintenance procedure can be time consuming and costly since the fluid processing system must be brought off-line for an excessive time period. Thus, it would be extremely desirable to provide an inexpensive fully encapsulated cell type filter assembly that could be readily removed from a fluid processing system, discarded after removal, and replaced with a new filter assembly.
Another problem associated with the use of conventional inline filtration systems such as a lenticular filtration systems is that of hold-up volume. This is the volume of excess process fluid which accumulates in the bottom of the filter housing below the outlet opening thereof. During routine maintenance, or when spent filtration cells are replaced, the filter housing must be opened. This can result in contamination of the excess process fluid which must then be discarded. In filtration systems employed in the manufacture of biopharmaceuticals or pharmaceuticals, process fluids can be extremely valuable, and the loss thereof due to contamination can be very costly. A prior art filter assembly which employs a mechanism for reducing or decreasing hold-up volume in a filter housing is disclosed in U.S. Pat. No. 5,462,675 to Hopkins et al. This prior art assembly does not however, provide a mechanism for recovering excess process fluids from a filter housing. Clearly, the provision of such a mechanism would be extremely desirable.
SUMMARY OF THE INVENTION
The filtration system of the subject invention provides a disposable cartridge housing which encapsulates a lenticular cartridge assembly including a plurality of axially spaced apart filtration cells. The filtration system employs several unique structural features which are not found in prior art filtration systems. These features include, among others, the manner by which the cartridge housing provides a positive sealing force between the cell media layers and between the lowest cell media layer and the cartridge housing, free of any gasket, O-ring, weld or bond; the manner by which the two generally hemispherical structural portions of the cartridge housing are connected to one another by vibration welding along a circumferential joint having a flash trap associated therewith to provide an aesthetically pleasing commercial product; the method by which unfiltered hold-up volume is drained from the cartridge housing, through a flexible connector hose and into a smaller exterior filtration unit to yield clean effluent; and the manner in which hold-up volume within the cartridge housing is reduced by placing an annular volume reducer within the cartridge housing below the lowest point on the filter assembly.
In brief, the subject invention provides a fluid filtration device which includes a capsule housing including an upper housing portion defining a fluid inlet and a lower housing portion defining a fluid outlet, a filter assembly including an elongated mounting post and a plurality of filtration cells supported on the mounting post in axially spaced apart relationship, and structure operatively associated with the mounting post and the lower housing portion for effectuating axial compression of the filtration cells relative to the mounting post when the mounting post is engaged in the lower housing portion during assembly, whereby a positive sealing force is established between each cell and between the lowermost cell in the filter assembly and the lower housing portion.
The structure for effectuating axial cell compression includes a radially extending compression flange formed at an upper end portion of the mounting post and an engagement fitting formed at a lower end portion of the mounting post. The engagement fitting of the mounting post is dimensioned and configured to engage an annular retention rib formed within the lower housing portion, coaxial with an annular support flange also formed in the lower housing portion. At least one annular sealing rib projects downwardly from a lower surface of the compression flange for sealingly engaging an upper layer of an uppermost filtration cell in the filter assembly, and at least one annular sealing rib projects upwardly from an upper surface of the support flange for sealingly engaging a lower layer of a lowermost filtration cell in the filter assembly. Preferably, annular spacer rings are positioned between adjacent filtration cells in the filter assembly and spacer rings include at least one upper sealing rib for engaging a lower layer of an adjacent filtration cell located thereabove and at least one lower annular sealing rib for engaging an upper layer of an adjacent filtration cell located therebelow.
As discussed briefly hereinabove, in a preferred embodiment of the subject invention, an annular volume reducer is disposed in the lower housing portion circumjacent the annular support flange for displacing excess process fluid which accumulates in the lower housing portion, and a drainage port is formed in the lower housing portion for facilitating drainage of excess process fluid therefrom. Additionally, a kit is provided for retrieving excess process fluid from the lower housing portion which is includes a conduit and a portable supplemental filtration unit. The conduit has a connector at one end for mating with the drainage port and a connector at the opposed end for mating with the supplemental filtration unit. The supplemental filtration unit has an outlet port for transferring the excess process fluid to a containment device.
In accordance with a preferred embodiment of the subject invention, the upper housing portion and the lower housing portion are joined together along an equatorial joint which is defined by a circumferential tongue on
Cizek Eric
Hamlin Thomas J.
Iturrino Laurie
Lucas Jeffrey A.
Olsen Daniel K.
Cecil Terry K
Cummings & Lockwood
Cuno Incorporated
Walker W. L.
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