Liquid purification or separation – With alarm – indicator – register – recorder – signal or... – Position or extent of motion
Reexamination Certificate
1999-06-17
2001-07-03
Drodge, Joseph W. (Department: 1723)
Liquid purification or separation
With alarm, indicator, register, recorder, signal or...
Position or extent of motion
C210S455000, C210S473000, C210S474000, C210S510100
Reexamination Certificate
active
06254768
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates generally to water filter carafes and more particularly to a cyst-reduction water filter carafe which can deliver substantial volumes of filtered water at relatively low (gravity-assisted) water pressures, the filtered water being substantially free of parasites and other impurities.
Gravity flow water filtration units continue to gain in popularity as consumers become concerned about the quality of available drinking water supplies. Carafe gravity flow units effectively address this concern because of their relatively low cost and perceived efficiency in removing unwanted tastes, odors, and harmful pollutants.
Operation of these units is simple and convenient. Water is simply poured into the top of the unit and is allowed to trickle through a replaceable filter cartridge to a treated water reservoir for later use. Early filter cartridges were typically packed-bed units containing carbon pellets for the removal of adsorbable/catalyzable constituents such as chlorine and organics, and ion exchange resins for the removal of metal ions such as lead. Bacteriostatic agents such as silver may also be present. More recently, cyst-reduction water filters incorporating cellular ceramic honeycomb filter elements of selectively plugged channel configuration have been developed. These filters, described for example in the co-pending, commonly assigned U.S. patent application of W. Cutler et al., Ser. No. 09/211,134 filed Dec. 14, 1998 (that application being expressly incorporated herein by reference), can provide true cyst reduction performance at gravity flow filtration rates of at least 200 ml/minute. By “cyst reduction” in a filter, filter system, or filtration process is meant a filter, filter system, or process capable of providing at least 99.95% removal of 3-4 &mgr;m particles from a raw water source when tested in accordance with NSF Standard 53, Drinking Water Treatment Units—Health Effects (September 1997).
Although filter designs and materials capable of effective cyst reduction exist, significant problems remain concerning appropriate methods and designs for incorporating such materials or filters into effective, gravity-fed water carafe purification systems. This is because cyst reduction pertains to a health concern, rather than a lesser concern about water taste and odor.
Any successful carafe filtration system must first prevent the mixing of unfiltered water with water already treated by the filter. Current carafe systems are not designed for cyst filtration. For example, that the seal positioned between the filter cartridge and the carafe inlet reservoir on a typical commercial carafe is typically a loose taper fit. Such seals readily allow unfiltered water to enter the filtered water chamber via the pour spout, reservoir/filter seal, and/or reservoir/carafe seal. In these designs, therefore, contamination of the raw water with unfiltered water can occur during filling, during the filtration process, or during pouring. Obviously, only minor leaks of raw water to the filtered water reservoir are needed to entirely negate the health benefits to be derived from the use of a cyst reduction filter element, no matter how effective the cyst removal of that element may be.
SUMMARY OF THE INVENTION
The present invention provides a gravity flow water carafe design offering true cyst reduction performance. Central to the design is a positive, locking seal between a gravity-flow cyst reduction filter cartridge and the raw water reservoir of the carafe. Positive cartridge locking elements, with or without additional gasketing, secure a seal with the reservoir such that no unacceptable leakage of raw water past the cartridge and into the filtered water reservoir of the carafe can occur.
In one particularly preferred embodiment, the water seal is provided by a twist lock cartridge mount that includes locking tabs or pins on the cartridge (or reservoir) to engage with slot or other tab receptacles on the reservoir (or cartridge). The locking tabs or pins can effectively restrict cartridge installation to only correct, properly sealing mounting positions. For user protection, locking indicators of this type, or other visual, tactile, audible or similar indicators should be provided on the cartridge or within mounting assembly to provide visual or other sensory confirmation that the cartridge is correctly mounted in and sealed against the carafe mounting.
Further preferred embodiments of the carafe of the invention may include additional features to prevent the mixing of unfiltered with filtered water during filling or pouring. For example, the raw water reservoir may be provided as a tightly fitting sub-assembly which forms a seal with the carafe pitcher. This seal prevents raw water entry into the filtered water reservoir during filling. Further, the raw water reservoir may be provided with a sealed or tightly fitting cover comprising only a smaller hinged rear section to be opened for filling. The sealed forward section of the cover guards against the inadvertent release of raw water along with the filtered water as the latter is being dispensed from the carafe. The rear hinged section of the cover also permits filling of the carafe without complete removal of the cover.
In a first aspect, then, the invention includes a water filtering carafe designed for the effective use of a gravity-flow cyst reduction water filter cartridge. The filter cartridge selected for use in the carafe may comprise conventional inlet(s) for the raw water to be filtered and one or more outlets for the filtered water. The carafe includes a first reservoir for the raw water to be filtered and a second reservoir for collecting and storing the filtered water processed by the cyst reduction filter.
The raw and filtered water reservoirs are separated and isolated from each other by a suitable water-tight partition, e.g. a wall section which may form part of the raw or filtered water enclosures, the partition including a mounting receptacle into which the water filter cartridge is mounted. The cartridge is mounted in the receptacle such that the cartridge inlet opening is in communication with the raw water reservoir and the cartridge outlet opening is in communication with the filtered water reservoir.
Critical to the effective operation of the carafe is cyst-blocking water seal between the water filter cartridge and the mounting receptacle. By a cyst-blocking seal is meant a water seal, provided as part of the cartridge, part of the mounting receptacle, or both, that is sufficiently water-impermeable that the minimum cyst reduction effectiveness required of the cartridge is preserved by the cartridge-carafe assembly. The specific performance characteristic exhibited by the carafes of the invention is that the combination of the water seal and water filter cartridge effect at least 99.95% removal of 3-4 &mgr;m particles from a charge of raw water released into the filtered water reservoir, when the particle removal is tested in accordance with NSF Standard 53, Drinking Water Treatment Units—Health Effects (September 1997).
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Dulieu Paul D.
Steiner Mark C.
Corning Incorporated
Drodge Joseph W.
Sterre Kees van der
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