Liquid purification or separation – Serially connected distinct treating with or without storage... – With by-pass
Reexamination Certificate
1999-12-15
2001-09-18
Savage, Matthew O. (Department: 1723)
Liquid purification or separation
Serially connected distinct treating with or without storage...
With by-pass
C210S262000, C210S266000, C210S282000, C210S289000, C210S316000, C210S317000, C210S436000, C210S472000, C210S502100, C210S510100
Reexamination Certificate
active
06290847
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to water filtration devices, which include a cyst-reducing water filter capable of reducing parasites and other impurities in drinking water and yet capable of delivering a substantial water flow rate at relatively low (gravity-assisted or gravity-flow) water pressures. While the invention may be used in other types of water filtration devices, it is especially suited for use in gravity-flow water carafes, and will be particularly described in that connection.
BACKGROUND OF THE INVENTION
Until recently, water filter carafes of commercially available design have not been capable of parasite reduction, which requires much finer filtration. Nor have they been effective for the significant reduction of organic chemicals, pesticides and insecticides, which requires more carbon. While such additional removal attributes are desirable, they have not been technically feasible in the filter sizes required and at the filter cost currently available in the market. In addition to the concerns about drinking water taste and odor, consumers are beginning to be more concerned with the quality of drinking water, thus increasing the demand for gravity-flow filter carafes. This is because such water filter carafes are relatively low in cost and operate in a simple manner. Water from a tap is simply poured into the top of the filtration unit and is allowed to flow through a replaceable filter cartridge to a treated water reservoir for later use.
A typical commercially available cyst-reducing water filter cartridge consists of a filter housing which contains a packed bed mixture of ion-exchange resin for the removal of unwanted ions, for example, lead, copper, and hard water ions, as well as carbon granules for the removal of adsorbable/catalyzable constituents such as chlorine and undesirable tastes and odors. Further, the filter housing contains a high surface area cyst-reducing filter element that is capable of removing harmful parasites and dirt that are present in water from a municipal water source. Without the cyst-reducing filter element, the housing containing the packed bed mixture that is commercially available for use in gravity-flow water carafes typically have physical volumes on the order of 165 cm
3
(10 in
3
). This suggests that a filter incorporating the additional cyst function using the current designs would require more volume than that mentioned above. Gravity cyst-reducing filters should be able to achieve the production of a reasonable quantity of filtered water in a reasonable time, preferably, approximately 1 liter in less than 12 minutes.
Although filter designs and materials capable of cyst reduction exist, significant problems remain concerning appropriate methods and designs for incorporating such filters into effective, gravity-assisted water carafe purification systems. In order to sustain adequate flow rates throughout the life of the filter, the design must be such that air entrapment within the filter must be minimized. In addition, the design should be such that either a hydrophilic or a hydrophobic microporous cyst-reducing filter element can be used to sustain maximum flow rates. Maximum flow rates are achieved when water has displaced the air in the filter pores. This displacement of air from the pores and its replacement with water can be referred to as priming and when this displacement process is complete the filter is referred to as being in the primed state. The maximum flow rate is achieved when the filter element remains in the primed state. The filter cartridge design should allow the cyst-reducing filter element to remain in the primed state, that is, the pores remain filled with water at all times. The inventive combination of a filter cartridge design which allows both proper cartridge venting and which keeps the filter primed is essential to a successful filter.
A design in which only one of the two factors is present will reduce flow. Designs which only allow the filter to remain in its primed state, but which neglect venting promote the development of air locks beneath the packed bed of ion-exchange resin which significantly diminishes or stops the water flow rate. Air locks can come from two sources, entrapped air bubbles and dissolved air. The tap water out of a faucet that is introduced into the filters is typically less than 55° F. Moreover, the tap water usually is directed first through an aerator which mixes air with the water and creates water that is full of bubbles. Some air enters the filter cartridge in the form of these bubbles, which penetrate into the filter cartridge and can coalesce with other bubbles to form larger bubbles which cannot get back out, thus, forming air locks within the cartridge. Secondly, air can enter and move through the cartridge in the form of dissolved oxygen and nitrogen. As the water temperature reaches room temperature or above the temperature of the original tap water, the solubility of these two gases decreases and the gases come out of the water, thus, forming air locks in the filter cartridge. Furthermore, designs which allow venting, but do not keep the filter in the primed state do not produce the maximum flow of water through the cartridge.
In light of the foregoing, it is desirable to provide a water filtration device that can provide a reduction of very fine particulate biological cysts and other impurities from drinking water. Also, it is desirable to provide a water filtration device that can deliver substantial volumes of filtered water at relatively low water pressures. In addition, it is desirable to provide a water filtration device that maintains the cyst-reducing filter element in a primed condition and prohibits the development of air locks, thus, providing an adequate filter flow rate. Furthermore, it is desirable to provide a water filtration device that promotes the removal of any air trapped within the filtration device itself and a filtration device that also prevents any water from bypassing the cyst-reducing filter element. Finally, it is desirable to provide a water filtration device that is replaceable and cost effective in the market place.
SUMMARY OF THE INVENTION
Accordingly, the present invention is directed to a water filtration device that substantially obviates one or more of the limitations and disadvantages of the related art. The principal advantage of the present invention is the provision of an arrangement which overcomes the limitations and disadvantages of the described prior arrangements. Additional features and advantages of the invention will be set forth in the description that follows, and in part will be apparent from the description, or may be learned by practice of the invention. The objectives and other advantages of the invention will be realized and attained by the apparatus particularly pointed out in the written description and claims hereof as well as the appended drawings.
To achieve these and other advantages and in accordance with the purpose of the invention, as embodied and broadly described, the water filtration device is a replaceable cyst-reducing water filter cartridge for use in a water filter carafe. The filter cartridge comprises a filter cartridge housing wherein a top rim of the housing is adapted for attachment to an untreated water reservoir receptacle of a water carafe. The housing further includes a compressed bed of ion-exchange resin that is disposed within an upper region and proximate to the top rim of the filter housing, wherein the compressed bed of ion-exchange resin is bounded at the top with a top screen and is bounded at the bottom with a bottom screen, wherein each of the top screen and the bottom screen is in full contact with the compressed bed of ion-exchange resin. The housing further includes a high surface area cyst-reducing filter element that is disposed within a lower region and proximate to a bottom rim of the housing, wherein the cyst-reducing filter element provides at least 99.95% removal of 3-4 &mgr;m particles when tested in accordance with NSF standard
Corning Incorporated
Murphy Silvy A.
Savage Matthew O.
LandOfFree
Gravity-flow water filtration device does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Gravity-flow water filtration device, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Gravity-flow water filtration device will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2438634