Patent Publication Number: US-5290443-A

Title: Faucet with microbial filter

Description:
BACKGROUND OF THE INVENTION 
     The supplying of microorganism-free water to users is a continuing technological problem, although water treatment is an old technology which finds use in virtually every city. Typically, the water is chlorinated to destroy microorganisms, with the chlorinating agents being added in quantities so that only minimal amounts of chlorine remain in the water after microorganisms and other organic materials have been neutralized by the free chlorine present. 
     One specific technical problem that remains to the present day is the problem with water that sits in stagnant manner in faucets between uses. Such water can exhibit a growth of microorganisms. Thus, when the faucet is turned on after a long period of disuse, the first aliquot of water delivered can have a relatively high bacterial count, even if the water was initially filtered and chlorinated. 
     This problem is addressed in Norton U.S. Pat. Nos. 4,676,896; 4,980,056; and 5,045,198. In the first cited patent, a faucet-mounted ultraviolet irradiation unit is provided for purification of water at the faucet, to inactivate bacteria that may have grown upstream in the line during a period of inactivity, and also to inactivate bacteria and virus present in the water as supplied. Such a unit of course requires electric power. 
     By this invention, a faucet-mounted water purifier is provided which requires no electric power, and which can be used for the reliable removal of bacteria, and even virus, from water as it passes through the faucet. Because the invention of this application is a faucet-mounted unit, it is capable of removing microorganisms from water which has remained in stagnant manner in the faucet region for a substantial period of time, with resulting bacterial growth. The faucet-mounted purifier of this invention can remove bacteria that are downstream from the conventional filters and irradiators of the prior art which are customarily used in water lines, so that even initial aliquots of water from a freshly turned-on faucet will be substantially microorganism free. 
     DESCRIPTION OF THE INVENTION 
     In this invention, a faucet-mounted filter is provided for water passing through the faucet, with the faucet defining a water flow line. A housing is positioned in flow transmitting relation with the water flow line of the faucet. Microporous filter means are positioned to sealingly occlude water flow through the housing. Thus, all water flow through the housing must pass through porous walls of the filter means. The pores of the walls are typically no larger than 0.22 micron, with the result that the filter is capable of microbial filtering. 
     Preferably, the pores of the filter walls are sized from 0.005 to 0.05 micron, as measured by the particle sizes they pass or block. Thus, it becomes possible not only to filter microorganisms which are of the size of bacteria, but also the filter of this invention may be an anti-viral filter, for removal of the smallest microorganisms. 
     Preferably, the faucet is connected to a source of prefiltered water of low turbidity and solids, to prolong the useful life of the filter means used herein. Thus, the filter means in this invention is used primarily to collect only small microorganisms and other particulate matter which passes through conventional water line filters. 
     The microporous filters used in this invention may be made of many varieties of hydrophilic microporous sheet fabrics and plastics including cellulose monoacetate, diacetate, or tracetate; or thin film composites of polyamide placed on a polysulfone layer or another fabric. Microporous sheet materials may also be made of a hydrophobic material such as polyethylene, polypropylene, poly-4-methylpentene-1, polyvinylidenefluoride, polytetrafluoropropylene, copolymers of hexafluoropropylene and tetrafluoropropylene, and copolymers of a fluorinated olefin monomer and an olefin monomer, by way of example. In addition, the filter of this invention may be made of microporous ceramic materials which are either homogenous or applied to substrates. Ceramic materials are extremely durable, and may be reconditioned after microbiological fouling or sealing, through the use of chemical cleansing agents and/or heat. Some ceramic membranes utilize a replaceable layer of microporous material, such as zirconium hydroxide, over a ceramic substrate. Such modules may be restored to original performance after fouling or scaling by removing and replacing the zirconium hydroxide or other microporous layer. 
     Physical designs of membrane modules that may be used in accordance with this invention are spiral wound edge type flow and spiral wound end type flow modules, as well as pleated wall modules, cylindrical sheet modules, and solid, cylindrical modules for example made of microporous plastic or ceramic. Such structures are all known to the art per se. 
     It is also preferred to provide means of draining the housing when water is not flowing therethrough. Such means is typically positioned upstream of the hollow fiber filter means, so that, when the faucet is off, the hollow fiber filter means will not stand for a long time in stagnant water. This reduces the possibility of bacteria penetrating through the hollow fiber walls by dividing and growing through the pores, which is a phenomenon that has been previously noticed with respect to bacterial filters. Preferably all flow line portions downstream of the filter are positioned to drain naturally. 
     Generally, a water pressure of about 40 psi or more is provided to the system. Such a water pressure will cause water to be forced through the pores of the hollow fiber filter for rapid flow when the faucet is open, even if the pores are hydrophobic. 
     Additionally, the microporous filter means may be positioned in its housing to sealingly occlude water flow through the housing, with the outer end of the filter being at the outermost end of the water flow line in the faucet. Thus, there is no downstream portion of the faucet where stagnant water can reside to breed bacteria. 
     It is often also desirable for at least portions of the inner wall of the housing to carry a coating of hydrophobic material such as polytetrafluoroethylene, to facilitate complete drainage of the housing between uses of the faucet. This is particularly advantageous since the filter membrane is thus kept away from the long term exposure to liquid water. This, in turn, suppresses the tendency of bacteria to grow through the pores of the filter, even although the pores are too small for the passage of normally-sized bacteria. 
     Additionally and preferably, prefiltered water of low turbidity and solids may be prepared by a reverse osmosis process and connected to the faucet as the desired source of water. The useful life of individual modules of the filters may thus be prolonged. 
     The filter of this invention may be in combination with a faucet defining a first water flow line and first flow valve means for controlling flow through the first water flow line. The housing which carries the filter is positioned in the faucet in flow transmitting relation with the first water flow line. Specifically, the housing may be positioned upstream from the first flow valve means. 
     The faucet may also include a second flow line and second flow valve means for the second flow line. The second flow line ma communicate with the first flow line downstream from the housing. Thus, water which has been filtered may be mixed as desired with another source of water, or it may be separately provided. For example, the first flow line may be connected at its upstream end to a source of pressurized water which has been purified by reverse osmosis. The second flow line may communicate with a different source of water, for supply as desired of alternate sources of water. 
     If desired, at least one of the flow lines may define thermostatically controlled valve means to limit the flow of hot water when the water is above a predetermined temperature. Thus, the filter means may be protected from excessively hot water. 
     It is also desirable with these multiple source faucet arrangements for the housing which communicates with a pair or more of flow lines to define drainage port means, to permit draining of water from the housing between uses of the faucet. Thus, the filter may be kept from long term contact with standing, stagnant water as described above to prevent the bacteria grow-through phenomenon. 
     The faucet-mounted filter of this invention is usable for difficult microorganism-removing situations. For example, it may be used to provide safe drinking water in regions where the water contains Giardia lamblia cysts, which are not easily inactivated by chlorination, or where the presence of any other microorganisms such as bacteria is expected. Similarly, the faucet-mounted filter of this invention can be used to remove virus from water, for example polio virus or rotavirus. 
     Additionally, the faucet-mounted filter of this invention may be used to &#34;polish&#34; ultrapure electronic chip manufacturing water. Such a post treatment of previously filtered water may be valuable in that a single bacteria can straddle two conductors on the surface of an electronic chip having microfine circuitry, causing a short circuit which ruins the chip. 
     The microporous, hollow fibers used in this invention may be hydrophobic in nature or optionally hydrophilic, as may be desired. 
    
    
     DESCRIPTION OF DRAWINGS 
     FIG. 1 is an elevational view, taken partly in section, of a faucet which carries a faucet-mounted filter of this invention; 
     FIG. 2 is an elevational view, taken partly in section, of another embodiment of a faucet carrying a faucet-mounted filter of this invention; 
     FIG. 3 is an elevational view, taken partly in section, of another embodiment of a faucet and faucet-mounted filter of this invention; 
     FIG. 4 is an elevational view, taken partly in section, of a multiple conduit faucet which carries a faucet-mounted filter of this invention; 
     FIG. 5 is another embodiment of multiple conduit faucet system, carrying a faucet-mounted filter of this invention; and 
     FIG. 6 is an elevational view, taken partly in section, of a third embodiment of multiple conduit faucet and faucet-mounted filter of this invention. 
    
    
     DESCRIPTION OF THE SPECIFIC EMBODIMENTS 
     Referring to FIG. 1, a conventional faucet 10 is disclosed having a water flow line 12 connected to a source of pressurized water, with the water flow through line 12 being controlled by a conventional valve and handle 14, which is shown in schematic manner. Water flow line 12 defines a distal, downwardly extending section 16 adjacent the water outlet end 18, which includes a filter housing 20 having an upper inlet 22 and a lower outlet 24 for flowing water. 
     The interior of filter housing 20 is occluded by a spiral wound membrane ultrafiltration module 26 of the known type where water enters along the edge 27 of a wound coil of ultrafiltration membrane 28, separated by coils of screening 29 with filtered water passing to apertured central tube 34 and from there through outlet end 18. 
     The size of the pores within the walls of membrane 28 may specifically be from about 0.01 to 0.02 micron, as determined by the maximum sized particles that they pass under pressure. Specifically, the membrane type and general design may be similar to the PERMASEP units sold by DuPont, but for size. 
     Accordingly, when handle 14 of the faucet is turned on and pressurized water passes through flow line 12, the pressurized water, being at typically 40 psi or greater, is forced through the pores of membrane 28, resulting in the filtering of bacteria-sized particles and the like. Then, the filtered water migrates in a spiral path to central tube 34, passing through apertures 36 in its side wall, to flow out of end 18, to provide the user with water which is free of bacteria, and preferably virus as well when the pores of membrane 28 are sized at the lower end of the possible size range. Cysts and protozoa of all kinds are of course also removed, since they tend to be of larger size than bacteria, along with small, nonliving particles and the like. 
     The water produced by the faucet-mounted filter of this invention is ultra pure, and typically suitable for critical electronic manufacturing processes, for consumption by immune-disabled individuals, or the like. 
     Turning to FIG. 2, a second faucet-mounted filter embodiment 40 is disclosed. In this embodiment, pressurized water line 42 is controlled by a conventional faucet valve 44 and terminates in a swan neck curved end 46 for delivery of purified water to the user. 
     Housing 48 is provided in flow line 42. Microporous, ceramic, cap-shaped filter 50 is positioned within housing 48, and sealed thereto at the top, being mounted in an annular mass of potting compound 56 on the outside only. Thus, as before, no flow of fluid can take place through housing 48 without the fluid passing through cup-shaped ceramic filter 50. 
     Additionally, housing 48 may define a lower drain 62 which causes housing 48 to drain when faucet valve 44 is closed. This, in turn, will cause the water in the system above drain 62 to flow rearwardly when the faucet is shut off to drain standing water from contact with ceramic filter 50. As stated above, such draining provides further assurance that bacteria cannot divide in the pores of the hollow fibers, reducing their size and migrating through pores that are normally bacteria blocking. 
     The flow capacity of drain 62 is low compared with the overall flow capacity of flow line 42, so that an ample quantity of processed water will flow through outlet port 46. 
     As an added advantage of such a drain system, when the faucet is off, water which has passed through ceramic filter 50 will flow backwards as water passes out of drain port 62. This can dislodge and remove some of the materials held back by filter 50 and cause it to be removed from the system out of drain 62, to provide an increased useful life to filter 50. Also, the filter may be cleaned by a pressurized backflush of water using drain port 62. 
     Referring to FIG. 3, faucet 70 is of similar design to the faucet of FIG. 1, except that the lower tip of the faucet has been omitted so that the outer annular end 72 of spiral wound filter module 26a is substantially at the outermost end 76 of the water flow line in the faucet. Filter module 26a may be of the design of filter module 26. Alternatively, as shown, module 26a may of spiral wound design where feed water flows from apertured central tube 34a into an end of spiral membrane 28a, to cross the membrane wall and then to pass downwardly out of annular end 72. If desired, a module may be used similar to that of Toray&#39;s ROMEMBRA Module. 
     As before, the faucet valve 14a controls flow through flow line 12a into housing 20a, which carries spiral filter module 26a. 
     As before, the pores of the hollow fiber walls are of a bacteria-blocking size as previously specified. 
     It is also preferred to connect the faucet of FIG. 3, and other embodiments of this invention as well, with a source of reverse osmosis water, to prolong the useful life of filter 26a. 
     Referring to FIG. 4, faucet 82 is provided in which the faucet defines three water flow lines 84, 86, 88, each being controlled by a valve 90 as shown. A pleated sheet filter 92 having bacteria-blocking micropores is provided in a housing 94, being arranged in first water flow line 84 which communicates through faucet neck 98. As shown, water flowing through line 84 passes upwardly through pleated filter 92 into an upper chamber 100, and from there through the particular valve 90 that controls first flow line 84. 
     Thus, pleated filter 92 positioned in housing 94 may be connected only to a source of reverse osmosis water or the like through first flow line 84, while cold tap water may be provided through a second flow line 86 and hot tap water through a third flow line 88. Thus, faucet 82 may be provided with three different sources of water, which can come together in chamber 102 to be mixed and expelled from faucet neck 98. 
     Thus, with a faucet of this type, the conventional hot and cold water sources are available, but, additionally, a source of purified, bacteria free water is available for drinking, or for special uses such as in the electronics field or the like. 
     Referring to FIG. 5, another embodiment of the faucet-mounted filter of this invention is shown. In this particular embodiment, faucet 104 carries a filter housing 109 and a bacteria blocking filter 108 of any desired design in accordance with this invention. Specifically, filter 108 may be of inverted microporous ceramic or plastic cup design. In this particular embodiment, housing 109 communicates with a pair of different flow lines 110, 112 for water to be filtered. Each of the flow lines carries a conventional faucet valve 114. Thus, water from both flow lines passes into housing 109 for filtering by means of plastic filter 108, to provide microbial filtering to the water passing therethrough. 
     As shown, one of the flow lines 112 has thermostatically controlled valve means contained in a housing 116. As shown, water from flow line 112 can enter into housing 116 through aperture 118, and exits therefrom through aperture 120, to pass onwardly to filter chamber 106. Typically, water line 112 is a hot water line, and it is desirable to protect the material of filter 108 from excessively hot water. 
     Accordingly, a bimetal bar or sheet thermostat 122 is provided, being positioned to close over outlet port 120 in the presence of a predetermined maximum water temperature, as shown in the dotted line position of thermostat 122. Thus, as the hot water temperature approaches the predetermined maximum temperature, thermostat 122 bends to cover outlet port 120, significantly restricting or terminating the flow of hot water through line 112. The material of filter 108 is accordingly protected from excessive temperature. 
     Upon cooling of the hot water in line 112, thermostat 122 will then back upwardly again, reopening access to outlet port 120. 
     Additionally, filter housing 109 defines a drain port 124 at a lower portion thereof so that, when both faucet valves 14 are closed, stagnant water will not be stored in housing 106, but rather will drain through hydrophilic filters 108, out of port 124, through tubing 126 which includes a conventional siphon break 128, to drain 130. Thus, the filter 108 may be kept from long-term contact with standing water which, as previously described, can increase the bacteria &#34;grow-through&#34; phenomenon, to reduce the effective bacteria-blocking characteristic of the faucet and mounted filter of this invention. 
     Referring to FIG. 6, faucet 132 is similar to the embodiment of FIG. 4, except that only two water flow conduits 134, 136 are present, being respectively controlled by faucet valves 138. 
     In this particular invention, faucet 132 may be generally a conventional faucet that is currently available at a plumbing supply store, having threaded connector ends 140, 142 for connection with other pipes. 
     By this invention, filter housing 144, which contains bacteria blocking filter 146 of a type previously described, defines a female, threaded connector 150 which is proportioned to connect with conventional connector 140 of faucet 132. At the opposed end, housing 144 defines a conventional threaded pipe connection 152 for joining with a conventional water pipe 154. Thus, the structure of FIG. 6 shows how generally conventional plumbing equipment can be used in conjunction with a module comprising housing 144, so that conventional plumbing ma be adapted by addition of the module to receive the faucet mounted microbial filter of this invention. 
     Accordingly, a faucet-mounted filter is provided for the production of ultrapure, microorganism-free water. Stagnant, bacteria-laden aliquots of water which have typically passed through conventional filter systems may be further purified, so that ultrapure water may be provided without fail to the user. 
     The above has been offered for illustrative purposes only, and is not intended to limit the scope of the invention of this application, which is as defined in the claims below.