Liquid purification or separation – With repair or assembling means
Reexamination Certificate
2001-06-28
2003-10-21
Lithgow, Thomas M. (Department: 1724)
Liquid purification or separation
With repair or assembling means
C210S444000, C210S450000
Reexamination Certificate
active
06635175
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a filter housing having a manifold and a bowl with a threaded ring there between to secure the bowl to the manifold. A filter cartridge is fixed to the interior of the bowl and can be removable therefrom. More particularly, it relates to a filter bowl and manifold which has a threaded ring retained in a fixed position relative either to the bowl or manifold and which is used to drive the bowl and manifold together or apart.
There are two basic types of filter housings used today for filter cartridges. The first and most recent is the disposable housing. Typically formed of plastic, it has a filter cartridge sealed inside. Once it has been used the entire device, housing, filter and all are simply thrown away. The second and more common type is the disposable filter cartridge in a reusable housing.
Although many different designs have been developed for a filtration module used in an ultrapure liquid filtration with a reusable housing, two designs are prevalent. In one module design, liquid to be filtered flows from one end of the filtration module to the other hand. In this class of the filtration modules, the feed and permeate connections are located at opposite ends of the filter thereby forcing the liquid flow to move from one end to the other. This flow configuration is referred to as an in line flow configuration. These filtration modules suffer from two disadvantages. First, they are more difficult to connect to the process equipment since the module is sandwiched between two sets of connections. Second, any free liquid remaining within the module quickly drains upon disconnection of the module because at least one connection is positioned at the bottom of the module.
A second filtration modular design locates all of the connections at the same end of the module. In this type of module, the feed and permeate ports are typically horizontally oriented at the top or “head” end of the module on opposite sides thereof. Due to their shape, these modules are referred to as having a T, L or U configuration. This configuration facilitates connection of the head to the remaining portion of the filtration module comprising the bowl and the filtration cartridge positioned within the bowl. In this design, the bowl and filtration cartridge comprise separate elements. Thus, when constructing the filtration module, the filtration cartridge and the bowl are separately secured to and sealed to the manifold head. In addition, upon completion of filtration the bowl and cartridge are separately removed from the head. This separate removal requires that the bowl be moved a distance substantially greater than the entire length of the cartridge in order to expose the cartridge to permit its removal. Thereafter, the exposed cartridge is removed by hand or with a hand tool. Since the filter cartridge is saturated with the liquid being filtered which is often times corrosive or toxic, the cartridge removal step presents a danger to the worker. In addition, since the bowl must be moved the length of the cartridge, the space within which the bowl and cartridge are positioned must accommodate this removal step.
In either of these embodiments, the bowl is removably attached to the manifold via a threaded ring that mates with threads on the manifold. The bowl and manifold are simply held together by the threaded ring. One or more filter cartridges are secured inside the bowl. To replace a filter cartridge, one simply removes unscrews the ring, pulls the bowl from the manifold, removes the cartridge, replaces it with a new cartridge reattaches the bowl to the manifold and then secures the threaded ring in place to maintain the connection between the two components.
This design presents several problems. First, the connection between the manifold and the bowl must be liquid tight. This typically accomplished with a series of O-rings between the manifold and bowl and/or the cartridge and the manifold. While forming a secure seal, during use the seal becomes somewhat fixed (or stuck together) and difficult to break when one tries to replace the spent filter.
Secondly, most of these systems hang vertically downward and require two hands to remove and reattach the bowl to the manifold
Even when the bowl and manifold separate easily, the bowl is not supported by anything, meaning that the bowl can easily drop either breaking the bowl or spilling its contents, which in many cases especially in the semiconductor industry is a hazardous material.
It has been proposed in U.S. Pat. No. 5,114,572 to provide a filter assembly which cooperates with a bowl to produce a filter cartridge-bowl construction which can be demounted as a single unit from a manifold. The filter cartridge is connected to the bowl by bayonet connections on the cartridge which fit into grooves within the interior surface of the bowl. This bayonet connection requires the flanges extending from the outside surface of the filter cartridge be positioned into grooves that extend vertically within the bowl and then into grooves which extend horizontally within the bowl. The connection configuration requires that the cartridge first be moved vertically into the vertical grooves and then be rotated into the horizontal grooves when mounting the cartridge into the bowl. Conversely, when it is desired to remove the cartridge from the bowl upon completion of a filtration process, the cartridge must be rotated and lifted from the bowl in a single motion. Since removal of the cartridge from the bowl requires application of force on the fluid conduit located at the top of the cartridge, and since the diameter of this conduit is smaller than the cartridge diameter there is no leverage of the application force on the cartridge. This, in turn, requires application of considerable force on the cartridge when effecting its removal from the bowl that may require the use of hand held tool. The application of a rotational force and a lifting force as a single motion increases the difficulty of separating the bowl from the filter cartridge. In addition, bowl rotation can dislodge the cartridge utilizing a bayonet connection. Separation of the cartridge from the bowl is particularly difficult when toxic or corrosive fluids have been filtered by this filtration device.
Further, current designs have the cartridge seal against and be lightly (friction fit) held to the manifold. Any application of back pressure when applied to the cartridge can cause the cartridge to unseat from the manifold, rendering it ineffective for filtration.
Accordingly, it would be desirable to provide a filtration module construction which avoids the need to remove the filtration cartridge separately than the bowl from the manifold while permitting the filter cartridge and bowl to be removed from a manifold as a single unit. In addition, it would be desirable to provide such a construction that avoids the need for applying force in a plurality of directions of movement to effect removal of a cartridge and bowl from a manifold. Such a construction would promote ease of separating the cartridge and bowl from the manifold, would eliminate the danger to the worker in removing the filtration cartridge subsequent to filtration and would reduce the space required to install the filtration module. Lastly, by forming the cartridge and the bowl as a unitary structure and securing that structure to the manifold, the problem of the cartridge becoming dislodged from the manifold when subjected to back pressure is avoided.
SUMMARY OF THE INVENTION
A filter cartridge housing formed of a manifold and a bowl is disclosed. A threaded ring substantially fixed in a position relative to either the bowl or the manifold is used to positively drive the manifold and bowl together and apart as needed and to form a secure and liquid tight seal between the two components when they are together. The threads of the ring mate with corresponding threads on component that does not contain the ring. The threaded ring is held in its substantially fixed position relative
Cook Paul J.
King Timothy J.
Lithgow Thomas M.
Mykrolis Corporation
Mykrolis Corporation
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