Abstract:
A water filter is packaged in a way that permits longer dwell time and greater volume in a dwell passage of the water filter. In one embodiment the water filter includes an influent passage where a biocide is imparted to the water, a dwell passage where the water remains in contact with the biocide for at least a predetermined duration, and an effluent passage where the biocide is removed from the water. The water filter includes a replaceable cartridge mounted in a pressure vessel. By arranging the dwell passage to include a pan shaped portion in the bottom of the vessel and an axial portion along the extremity of the cartridge, greater volume, greater mixing, and more effective disinfecting result. Another embodiment includes a series of baffles on the exterior surface of the cartridge that create further turbulence for mixing the biocide with the water.

Description:
This Appln is a 371 of PCT/US97/22101, Dec. 5, 1997, which is a con of application Ser. No. 08/761,651, Dec. 6, 1996, now U.S. Pat. No. 5,908,553. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     Embodiments of the present invention relate to water processing and to systems for purifying drinking water. 
     2. Background 
     As an introduction to problems solved by the present invention, consider the conventional water filter of the type described in U.S. Pat. No. 5,407,573 to Hughes, U.S. Pat. No. 4,888,118 to Barnes, and U.S. Pat. No. 5,401,399 to Magnusson, each incorporated herein by this reference. Such a filter has a generally axial flow of water from inlet to outlet ports. Influent water is imparted with a biocide, after which the water flows for a duration through an otherwise empty cavity sometimes referred to as an extended time chamber. While in the extended time chamber, time is allowed for the biocide to react with and kill bacterial and viral microorganisms in the water. 
     A greater disinfectant rate, i.e., kill rate, is possible by maintaining contact for a longer duration. However, using conventional techniques, extended time chambers having high kill rates are bulky in volume, limited in maximum flow rate, heavy, awkward to maintain, and expensive to manufacture due to the overall size required for extended time chambers in linear flow water filters. 
     In many applications of water purifiers, small size, light weight, and convenient maintenance are extremely important. Water purifiers are used in portable applications from patient care in hospitals, clinics, and emergency facilities to personal uses by hikers and rescuers. A variety of water purifiers are used in food and beverage manufacturing and dispensing throughout the world. 
     In view of the problems described above and related problems that consequently become apparent to those skilled in the applicable arts, the need remains in water purifiers for more effective apparatus capable of processing higher flow rates in a small, light weight package. 
     SUMMARY OF THE INVENTION 
     Accordingly a water purifier in one embodiment of the present invention includes a head and a pressure vessel. The vessel has a cavity. The head includes an influent passage for receiving the water and an effluent passage. The vessel includes a first passage in fluid communication with the influent passage and a second passage in fluid communication with the effluent passage. The first passage includes a treating system for increasing a biocide concentration in the fluid and an opening for discharging treated fluid into the cavity. The second passage includes a filtering system that receives the discharged treated fluid from the cavity for decreasing the concentration. 
     According to a first aspect of such a purifier, the effectiveness of the biocide in the water is proportional to the volume of the cavity and the flow rate of water through the purifier. For purifying a different flow rate, or for purifying the same flow rate more effectively, a vessel having a different cavity volume can be used in place of the original vessel. 
     According to another aspect, as opposed to a linear flow filter installed for inlet and outlet ports in coaxial or juxtaposed in parallel arrangement, the purifier of the present invention is characterized by more efficient use of its interior volume. Smaller and lighter purification apparatus results. 
     A water purifier according to another embodiment includes a dwell passage having a casing or partition. The partition has a plurality of holes allowing passage of the water through, rather than around, the partition. According to a first aspect of such an embodiment, the purifier is adaptable to efficiently process a lower flow rate by forming additional holes in the partition. Hence, when the dwell passage is too long, the flow path is easily shortened to accommodate changing circumstances, different fluids, or customer tailored installations. According to another aspect, the casing surrounds a replaceable cartridge. Water treated with a biocide is discharged from the cartridge. Discharged, treated water re-enters the cartridge after passing for a period of time through a dwell passage outside of the cartridge. By arranging the dwell passage outside the cartridge, the same cartridge can be marketed to many flow and purification applications having various sizes of pressure vessels, saving on manufacturing tooling, testing, and handling costs. 
     The present invention is practiced according to a method in one embodiment for increasing the effectiveness of a biocide in a water purifier. The water purifier includes a cartridge operative within an enclosure. The enclosure is characterized by a first volume that retains water in contact with the biocide. The method includes the step of replacing the enclosure with a second enclosure characterized by a second volume larger than the first volume. 
     These and other embodiments, aspects, advantages, and features of the present invention will be set forth in part in the description which follows, and in part will become apparent to those skilled in the art by reference to the following description of the invention and referenced drawings or by practice of the invention. The aspects, advantages, and features of the invention are realized and attained by means of the instrumentalities, procedures, and combinations particularly pointed out in the appended claims. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a cross section of a cylindrical water purifier in one embodiment of the present invention. 
     FIG. 2 is a cross section of a cylindrical water purifier in another embodiment of the present invention. 
     FIG. 3 is a cross section of a cylindrical water purifier in yet another embodiment of the present invention. 
     FIG. 4 is a cross section of a cylindrical water purifier in still another embodiment of the present invention. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     FIG. 1 is a cross section of a water purifier in one embodiment of the present invention. Water purifier  5  is cylindrical about a central axis  12  and has a substantially circular symmetry about that axis. Structural members of water purifier  5  are manufactured from polypropylene by conventional molding, extrusion, and machining operations. Water purifier  5  includes head  14 , canister  20 , and cartridge  80 . Head  14  and canister  20  together constitute a housing for cartridge  80 , which in some applications is replaceable, allowing the housing to be reused with a new or renewed cartridge. Cannister  20  comprises peripheral sidewall  21  and bottom wall  23 . 
     On installation, head  14  is connected to a water supply at the influent portion  18  of the influent passage and to a downstream device at an effluent portion  16  of the effluent passage. Cartridge  80  is inserted into head  14  by inserting neck  26  and shoulder  30  into head  14 . As canister  20  is threaded into threaded bore  22 , post  44  urges cartridge  80  further into sealing relationship with head  14 . O-rings  24 ,  28 , and  32  provide a removable fluid seal between cartridge  80  and head  14 . In operation, water flow through water purifier  5  is described as flowing in sequence through an influent passage, a dwell passage, and an effluent passage. The influent passage includes influent portion  18  in head  14 , central opening  13  in neck  26 , and chamber  38  which is defined by central tube  39  and filled with iodine treated resin granules  34 . Water flow is considered to be axial through chamber  38  because inlet and outlet are arranged on a common axis and the chamber contents are homogeneous, not containing flow directing surfaces or devices. 
     Granules  34  are retained in chamber  38  by polyurethane foam pads  36  and  40 , which also remove debris from the water and maintain the granules firmly packed and thereby help to prevent channeling. The granules  34  and foam pads  36  and  40  together define a water treatment system contained within the hollow interior or chamber  38  of tubular conduit or central tube  39 . Granules  34  impart a biocide to the water, for example, iodine ions. Equivalent biocides include, for example, iodinated polyvinylpyridine of the type disclosed in U.S. Pat. No. 4,594,392, incorporated herein by this reference, and conventional halogenated resins in loose powder, bead, or sintered porous block form. 
     Water with biocide flows from the influent passage through a radially spaced holes  42  into the dwell passage. Chamber  38  is joined with conventional hot glue to cartridge base  48  that seals the influent passage from the effluent passage, preserving the fluid flow integrity of the dwell passage. Equivalent joining techniques include, for example, using fasteners, screws threads, or a bayonet, sonic or other conventional welding, swaging, and forming for press fit. 
     The dwell passage includes a first nonaxial portion  46  and a first axial portion  50 . Dwell passage portions  46  and  50  are open cavities containing no filtering or processing apparatus. Water flow in dwell passage portion  46  is nonaxial in part because the inlet and outlet are not arranged on one axis. Though flow in the embodiment shown is primarily radial, due to the relative dimensions of the passage shown, flow is also considered nonaxial in an alternate canister having a comparatively large cavity below cartridge  80 . Note that although a portion of the influent and effluent passages are within the external diameter of the cartridge, some portions of the dwell passage are not. 
     As water flows through portions  46  and  50 , the biocide imparted to the water in the influent passage mixes with the water, killing microorganisms and other pathogens, sterilizing the water. Such sterilization proceeds over time. Time in the dwell passage is dependent on flow rate through the water purifier. As a consequence of the flow pattern in water purifiers of the present invention, the dwell time in the dwell passage is easily adjusted in response to a demand for increased water flow rate. When water flow rate is to be increased, canister  20  is replaced with a canister having a larger volume in dwell passage portion  46 ,  50 , or both  46  and  50 . An acceptable level of sterilization is then provided on the increased flow without replacing the cartridge, though the cartridge may require more frequent replacement. 
     The effluent passage includes axial portion  72 , radially spaced holes  73  through shoulder  30 , and an effluent portion  16  of head  14 . Filter block  75  of the filter cartridge  80  is preferably a solid cast carbon block  70  with outer surface  71  and inner surface  74 , having a nominal porosity of 0.5 microns to reduce the concentration of volatile organic contaminants, chemicals, parasites, sediment, biocide, and consequent suspended and dissolved materials including killed microorganisms and pathogens. Water flow in portion  72  is considered axial in aggregate, though fed from a surface rather than a coaxial opening. 
     In summary, water flow through water purifier  5  includes a dwell passage having a nonlinear, circuitous portion. Flow directions in passages  46  and  50  are dissimilar and in part opposite, promoting longer duration of exposure to biocide, adjustable dwell time, and better mixing of biocide with the water. These attributes promote more effective purification, more effective sterilization, and consequently wider application of water purifier  5  over known devices. 
     FIG. 2 is a cross section of a water purifier in another embodiment of the present invention. Water purifier  6  is cylindrical about a central axis. Numbered items in FIG. 2 correspond in structure and function to the items in FIG. 1 that are numbered one hundred less. Water purifier  6  uniquely includes cartridge  182 . Cartridge  182  includes cartridge cap  183  joined conventionally to cartridge body  184 . Cartridge body  184  and cap  183  form an exterior casing surrounding the filter portion and effluent passage of cartridge  182 . 
     Water flow through the dwell passage of water purifier  6  proceeds through first nonaxial portion  146  and first axial portion  150 , through radially spaced holes  152  and into second axial portion  154 . Water flow re-enters cartridge  182  from dwell passage first axial portion  150  through radially spaced holes  152 . Cartridge body  184  serves as a partition, dividing the dwell passage into two portions  150  and  154 . By admitting water only at the furthest axial extent of portion  150 , the minimum dwell time is improved over that for water purifier  5 , discussed above. 
     FIG. 3 is a cross section of a water purifier in yet another embodiment of the present invention. Water purifier  7  is cylindrical about a central axis. Numbered items in FIG. 3 correspond in structure and function to items in FIGS. 1 and 2 that are numbered two hundred less or one hundred less, respectively. Water purifier  7  uniquely includes cartridge  285 . Cartridge  285  includes cartridge cap  286  joined conventionally to cartridge body  287 . Cartridge body  287  and cap  286  form an exterior casing surrounding the filter portion and effluent passage of cartridge  285 . 
     Cartridge body  287  serves as a partition, dividing the dwell passage into two portions  256  and  254 . Cartridge body  287  includes a series of baffles formed as annular ribs encircling cartridge body  287  for interrupting, e.g. obstructing, linear water flow over the exterior surface of body  287 . Baffles are of two diameters: a smaller diameter baffle  225  allows water passage around the extremity of the baffle; and a larger diameter baffle  227  predominantly permits water flow through radially spaced holes  229 . Baffles of the larger diameter similar to baffle  227  fit snugly against the inside surface of canister  220 . Each baffle operates merely to mix the biocide into the water, enhancing sterilization, by obstructing linear flow. Therefore, no sealing relationship need exist between larger diameter baffles and canister  220 . 
     Water flow through the dwell passage of water purifier  7  proceeds through first nonaxial portion  246 , through second nonaxial portion  256 , through radially spaced holes  252 , and into first axial portion  254 . Thus, water flow reenters cartridge  285  from dwell passage second nonaxial portion  256  through radially spaced holes  252 . 
     Turbulent flow in water purifier  7  increases exposure of biocide to microorganisms and pathogens over water purifiers  5  and  6 , discussed above. Introducing baffles into passage  256  promotes mixing which improves exposure. 
     In an alternate and equivalent embodiment, all baffles fit against canister  220 , however linear flow is obstructed by aligning the respective radially spaced holes on different clockings about axis  212 . 
     FIG. 4 is a cross section of a water purifier in still another embodiment of the present invention. Water purifier  8  is cylindrical about a central axis. Numbered items in FIG. 4 correspond in structure and function to items in FIGS. 1,  2 , and  3  that are numbered three, two, or one hundred less, respectively. Water purifier  8  uniquely includes cartridge  388 . Cartridge  388  includes cartridge cap  389  conventionally joined to cartridge body  390  and granular filter material  367 . 
     Water flow through the dwell passage of water purifier  8  proceeds through first nonaxial portion  346 , through first axial portion  350 , through second nonaxial portion  360 , through first radially spaced holes  362 , and into third nonaxial portion  364  and then through holes  366  to portion  374 . Thus, water flow re-enters cartridge  388  from dwell passage first axial portion  350  through radially spaced holes  362 . By admitting water to the cartridge only at the furthest axial extent of portion  360 , the minimum dwell time is improved over that for water purifiers  5 ,  6 , and  7 , discussed above. 
     The effluent passage of water purifier  8  includes axial portion  374 , accumulator passage  369 , radially spaced holes  371 , axial passage  372 , and portion  316  of head  314 . To provide the same function as carbon block filter  70 ,  170 , and  270  in water purifiers  5 ,  6 , and  7  respectively, effluent passage portion  374  is filled with granular activated carbon filter material  367 . 
     In all of the above embodiments, holes described as radially spaced describe a ring of holes at substantially the same radius from a central axis. Such holes are essentially circumferentially spaced holes. In alternate and equivalent embodiments, hole patters are randomly distributed, distributed on the arms of a star pattern, are replaced by slots, or are replaced by openings formed between structural elements. 
     Canisters  20 ,  120 ,  220 , and  320  exemplify cylindrical pressure vessels. In alternate and equivalent embodiments, a pressure vessel having other than circular cross section is used, including elongated polygon, square, and spherical vessels. In still further alternate embodiments, the cartridge is integral to the vessel. In such embodiments, a partition formed in the vessel serves the functions described for the cartridge body in the illustrated embodiments. 
     Treating means for increasing a biocide concentration in water include materials including resins that impart a biocide such as a reactant, a catalyst, or an organic material or organism. 
     Filtering means for decreasing a concentration of biocide in water include conventional filters, as well as materials including resins that trap or absorb ions, chemicals, and organic matter. 
     The foregoing description discusses preferred embodiments of the present invention, which may be changed or modified without departing from the scope of the present invention. Alternate and equivalent water purifiers having the same dwell passage flow pattern use various known means for imparting biocide to the water and known means for removing biocide and other particulates and dissolved substances from the water. For example, alternate and equivalents for filter blocks  75 ,  175 , and  275  include an outside layer of filter material to obstruct the flow of debris including microscopic materials. These and other changes and modifications are intended to be included within the scope of the present invention. 
     While for the sake of clarity and ease of description, several specific embodiments of the invention have been described; the scope of the invention is intended to be measured by the claims as set forth below. The description is not intended to be exhaustive or to limit the invention to the form disclosed. Other embodiments of the invention will be apparent in light of the disclosure and practice of the invention to one of ordinary skill in the art to which the invention applies.