|Publication number||US20050023211 A1|
|Application number||US 10/924,066|
|Publication date||3 Feb 2005|
|Filing date||23 Aug 2004|
|Priority date||27 Aug 1998|
|Also published as||CA2302701A1, CA2302701C, EP1064069A1, EP1064069A4, US6550622, US6797167, US20020139746, US20030111404, WO2000012194A1, WO2000012194A8|
|Publication number||10924066, 924066, US 2005/0023211 A1, US 2005/023211 A1, US 20050023211 A1, US 20050023211A1, US 2005023211 A1, US 2005023211A1, US-A1-20050023211, US-A1-2005023211, US2005/0023211A1, US2005/023211A1, US20050023211 A1, US20050023211A1, US2005023211 A1, US2005023211A1|
|Original Assignee||Koslow Evan E.|
|Export Citation||BiBTeX, EndNote, RefMan|
|Patent Citations (9), Referenced by (13), Classifications (48), Legal Events (1)|
|External Links: USPTO, USPTO Assignment, Espacenet|
1. Field of the Invention
The present invention relates to filters and filter media. More particularly, the present invention relates to a composite filter media for filtering contaminants from a fluid and fluid filters containing the composite filter medium.
2. Description of the Prior Art
Fluids, such as liquids or gases, typically contain contaminants which include particulates, chemicals, and organisms. In many cases, it is desirable to remove some or all of such contaminants from the fluid. Usually, contaminants are removed from a fluid supply by passing the fluid through a filter whereby the contaminants are separated from the filtered fluid or filtrate.
Water is probably the most highly filtered fluid as it is filtered in industrial processes as well as in the household. Purification of water to produce potable water often requires the simultaneous reduction of particulate contaminants, dissolved organic chemicals and inorganic heavy metals. Particulate contaminants may include dirt, rust, silt, and other particles as well as potentially hazardous microorganisms such as chlorine resistant protozoan cysts, such as Cryptosporidium Parvum or Giardia, or bacteria such as Cholera and E. coli. Organic chemicals may include those that contribute to taste and odor as well as potentially toxic pesticides, chlorinated hydrocarbons, and other synthetic organic chemicals. Free chlorine reduction is also a major objective when the residual concentration of this disinfectant is sufficiently high to cause a bad taste. The most common heavy metal found in domestic water is lead derived from brass fixtures, leaded solder, lead pipes or other sources. Other heavy metals often found in drinking water include copper, zinc, manganese and iron.
The most common household water filters are typically small trapezoidal shaped plastic containers filled with a loose adsorbent medium such as activated carbon, ion exchange resins or zeolites. Water is filtered by such water filters by passing it through the loose adsorbent medium in an axial direction from a wider to a narrower portion of the trapezoidal container.
The trapezoidal shaped filter element is often used in a carafe and when used in a carafe is typically called a gravity-flow carafe filter. Such filters are typically installed within a household carafe having an upper reservoir, a lower reservoir and a filter receptacle fitted at the bottom of the upper reservoir. The trapezoidal shaped filter element is installed in the carafe by wedging it into the receptacle so as to effect a seal between the two reservoirs. Water passing from the upper reservoir to the lower reservoir must pass through the filter element. Typically, water enters the filter element through a series of small perforations at the wider top of the trapezoid. The water flows through the filter to the narrower bottom while traversing the porous bed of loose adsorbent. The water passes through a series of micro perforations in the narrower bottom of the filter exiting into the lower reservoir. In some filters, one or more non-woven pads, functioning as a fines filter, may be installed at the bottom, top or both bottom and top of the filter element to prevent the release of fine particles from the adsorbent bed.
The flow rate through present day gravity-flow carafe filters as described above is generally slow, typically about 200 ml per minute for a filter loaded with 100 grams of mixed wet resin-carbon filter medium containing water in an amount of about 30 to 35 percent by weight. The slow flow rate occurs because: (1) the water must traverse a deep bed of adsorbent particles; (2) the filter operates in a low pressure environment—only the pressure of the overlying water in the upper reservoir, typically several inches of water, is available to force the water through the filter; and (3) the size of the adsorbent particles are limited. Excessively large particles that would permit faster flow rates, would also have slower adsorption kinetics. This forces the use of relatively small particles (about 35 mesh) having faster adsorption kinetics but greater flow restriction. In view of the above constraints, a liter of water normally takes about 5 to 10 minutes or more to process through the present day carafe filter.
It is desirable to have a high flow rate, gravity-flow carafe filter which is capable of intercepting the very small chlorine resistant cysts such as Giardia and Cryptosporidium Parvum. It is also desirable to provide a high flow rate, gravity-flow carafe filter with enhanced chlorine, taste and odor reduction as well as a filter that can absorb heavy metals such as lead. It is desirable to provide a high flow filter that supports high flow with a 1 inch water column and that intercepts 99.95 percent of 3 to 4 micron particles which makes it suitable for cyst reduction and which generally meets NSF Class 1 particle reduction requirements. Mass production of carafe filters with simple equipment and at low cost is a necessity.
It is a primary object of the present invention to provide a fluid filter that is capable of filtering contaminants from a fluid at relatively high flow rates while providing a relatively low resistance to fluid flow.
It is another object of the present invention to provide a fluid filter capable of filtering chlorine resistant cysts such as Giardia and Cryptosporidium Parvum.
It is yet another object of the present invention to provide a high flow rate carafe filter with enhanced chlorine, taste and odor reduction as well as a filter that can absorb heavy metals such as lead.
It is still another object of the present invention to provide a carafe filter that can be mass produced with simple equipment and at low cost.
In accordance with the objects of the present invention, the foregoing primary objective is realized by providing a low flow resistance composite filter medium for removing at least 99.95 percent of particulates of a size in the 3 to 4 micron range and dissolved chemical contaminants from a fluid comprising an adsorbent layer containing an adsorbent agent and a hydrophilic particulate intercepting layer disposed adjacent to the adsorbent layer. The composite medium has a mean flow pore diameter of about 1 to 10 microns, a bubble point of about 3 to 15 microns and an air permeability of about 0.5 to 7 liters per minute/cm2 with a pressure drop of about 0.1 bar.
Other objects and advantages of the invention will be apparent from the following detailed description and the accompanying drawings.
The drawings, not drawn to scale, include:
The hydrophilic particulate intercepting layer 19 in the embodiment shown in
Of course those skilled in the art will now appreciate that the steps for making the first embodiment illustrated in
Generally, non-woven fibrous materials, such as high strength spunbonded polyesters or polyolefins, wet or dry laid fibrous materials and porous membranes can be used to form the adsorbent supporting 12 and fiber supporting 20 web substrates illustrated in the
Referring to the embodiment in
In commercially available filtering water carafes, a pressure drop of about no more than about 1 to 3 inches of water is available to push water through a filter medium. To make a high flow filter with the composite filter medium 10 of the present invention which is suitable for such end applications, the adsorbent layer 11 and the particulate intercepting layer 19 are selected from the materials described above such that when tested with a COULTER Porometer II, the composite filter medium has a mean flow pore diameter of about 1 to 10 microns, a bubble point in the range of about 3 to 15 microns and an air permeability rating of about 0.5 to 7 liters per minute/cm2 with a pressure drop of about 0.1 bar. Mean flow pore diameter is the pore diameter at which 50 percent of the flow is through pores that are larger and 50 percent of the flow is through pores that are smaller. Bubble point indicates the largest pore size in the filter medium and air permeability is the flow rate of a gas through the sample at a given differential pressure. Those skilled in the art will appreciate that optimization of the composite filter medium in the various illustrated embodiments to obtain the above described flow properties can be achieved by one or more of the following: (1) varying the density, fiber diameter and basis weight of the glass micro fiber and resin mixture; (2) including or excluding the overlying substrate, the intermediate substrate or both; (3) varying the adsorbent and binder particle sizes, concentrations and lay down weights; and (4) varying the properties of the web substrate by use of different materials.
All of the embodiments of the composite filter medium illustrated in
In the embodiment in
When the panels 108 a-108 d are made to be relatively large due to the desire to have a high surface area of filter medium in the filter 100, the filter 100 may be provided with one or more drainage support members to prevent collapsing of the filter medium upon itself. If unsupported, collapsed filter surfaces would close and could increase the pressure drop across the filter and undesirably restrict fluid flow through the filter. As illustrated in
Any of the above described filters employing the filter medium of the present invention can be used in a gravity flow, filtering carafe. As shown in
As can be seen by the foregoing discussion, the filter medium of the present invention is very useful for making filters for water filtering carafes because it permits the use of filter configurations capable of providing high filtration flow rates with the several inches of water pressure that is typically available in such carafe filters. The high flow rate is a result of a substantially increased cross-sectional filter flow area (up to about 20 times) as compared to a traditional trapezoidal carafe filter element. Accordingly, because a greater cross-sectional flow area may be provided, the adsorbent bed depth presented to the flow of fluid can be reduced by up to 60 times as compared to conventional carafe filter elements.
Also, to take advantage of the increased cross-sectional area provided by the filter medium of the present invention, the size of adsorptive particles can be reduced from the size currently in use with conventional carafe filters. Because smaller particles provide better adsorption kinetics, the overall performance of the filter of the present invention can be greatly improved as compared to the conventional carafe filter under the same pressure drop and flow rate conditions. Use of small adsorbent particles that are more effective allows a substantial reduction in the volume of adsorbent required to meet performance goals. The low flow resistance provided by the filter medium of the present invention can be used to intercept very small particles, such as those within the 3 to 4 micrometer range, a range which is required to intercept waterborne pathogenic oocysts such as Giardia and Cryptosporidium Parvum.
As can be seen from the foregoing detailed description and drawings, the filter of the present invention permits high filtration flow rates to be obtained in low pressure environments, such as those typically found in gravity flow carafe filters. Although the filtering apparatus has been described with respect to one or more particular embodiments; it will be understood that other embodiments of the present invention may be employed without departing from the spirit and scope of the present invention. Hence, the present invention is deemed limited only by the appended claims and the reasonable interpretation thereof.
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|US9028690||18 Apr 2012||12 May 2015||3M Innovative Properties Company||Water treatment cartridge|
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|US20040178142 *||19 Sep 2003||16 Sep 2004||Koslow Evan E.||Integrated paper comprising fibrillated fibers and active particles immobilized therein|
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|U.S. Classification||210/490, 210/502.1, 210/503, 210/506|
|International Classification||B01J20/08, B01D46/24, B01J20/06, B01D39/16, B01D39/14, B01D46/10, B01D46/52, B01D29/01, B01J20/26, B32B5/30, B01D29/07, B01J20/10, D04H3/16, C02F1/28, B01J20/28, B01J20/00, C02F1/42, C02F1/00, C02F1/44|
|Cooperative Classification||C02F2307/04, B01J20/28023, C02F1/444, B01J20/2803, B01D39/1623, C02F1/42, B01J20/28028, B01J20/28052, B01J20/00, B01J20/28033, C02F1/003, C02F1/281, B01J20/28004, B01J20/28085, C02F1/283|
|European Classification||B01J20/28D8, B01J20/28D40, B01J20/28F12F, B01J20/28B4, B01J20/28D20, B01J20/28D24, B01D39/16B4, B01J20/28D16, C02F1/00D4, B01J20/00|
|30 Nov 2006||AS||Assignment|
Owner name: KX INDUSTRIES, LP,CONNECTICUT
Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNORS:KOSLOW, EVAN E.;KOSLOW TECHNOLOGIES CORPORATION;REEL/FRAME:018688/0565
Effective date: 20051128