Patent Application
20100006494
The present invention relates to filter coalescer cartridges, and more particularly to filter coalescer cartridges including filter and coalescer media with anti-microbial properties.
Filter coalescer cartridges are typically a critical component of jet fuel refueling filtration equipment. The filter coalescer cartridges are employed to capture solid contaminants, and to coalesce water that may be present in the fuel. Such a filter coalescer cartridge is disclosed in commonly owned U.S. Pat. No. 6,569,330, hereby incorporated herein by reference in its entirety.
State of the art filter coalescer elements typically contain a plurality of media sections adapted to facilitate the capture of solid contaminants and the coalescence of water that may be present in the fuel. Historically, the outermost media section has been an outer cotton knit sock formed from woven unbleached cotton fibers. The chemistry and fiber morphology of unbleached cotton provides desirable water droplet growth properties to the outermost media section of the filter coalescer.
Although the natural unbleached cotton fiber provides the desired water droplet growth properties, the cotton fibers have poor anti-microbial properties. Microbes are known to be present and to grow in water and hydrocarbons. Additionally, the cotton fibers are a source of food for the microbes which typically attach to the cotton fibers and grow thereon. Over time the microbes can grow and consume the cotton fibers making it necessary to replace the outer cotton knit sock, or the entire filter coalescer cartridge, to maintain a desired performance of filter coalescer cartridge.
One method commonly employed to inhibit the growth of microbes on the cotton fibers of the knit sock has been to treat the cotton with an anti-microbial compound such as a boron or an arsenic based chemical compound, for example. However, the anti-microbial compounds are typically either water or hydrocarbon soluble and, therefore, are dissolved and rinsed from the cotton fibers during service. Accordingly, the anti-microbial protection for the cotton knit-sock is lost during service which reduces the service life of the cotton knit-sock.
It would be desirable to produce a new and improved filter coalescer having an outer sock with imbedded anti-microbial properties to extend the service life of the filter coalescer.
Compatible and attuned with the present invention, a new and improved filter coalescer having an outer sock with imbedded anti-microbial properties to extend the service life of the filter coalescer, has surprisingly been discovered.
In one embodiment, a filter coalescer cartridge for treating jet fuel comprises a pleat block assembly; a fiber wrap surrounding the pleat block assembly; and a knitted sock material surrounding at least the fiber wrap, the knitted sock material including a metallic silver to provide an anti-microbial property to the sock material.
In another embodiment, a filter coalescer cartridge for treating jet fuel comprises a pleat block assembly; a fiber wrap surrounding the pleat block assembly including a first glass fiber layer having an inner and an outer surface, a second glass fiber layer having an inner and an outer surface surrounding the outer surface of the first glass fiber layer, and a fluid pervious support layer surrounding the outer surface of the second glass fiber layer; and a knitted sock material surrounding at least the fiber wrap, the knitted sock material formed form a plurality of cotton threads woven together, the threads including at least one plastic filament having metallic silver particles disposed thereon to provide an anti-microbial property to the sock material.
In another embodiment, a process for forming a filter coalescer for treating jet fuel comprises forming a pleat block assembly; forming a fiber wrap surrounding the pleat block assembly; and forming a knitted sock material surrounding at least the fiber wrap, the knitted sock material formed form a plurality of cotton threads woven together, the threads including at least one plastic filament having metallic silver particles disposed thereon to provide an anti-microbial property to the sock material.
The above, as well as other advantages of the present invention, will become readily apparent to those skilled in the art from the following detailed description of a preferred embodiment when considered in the light of the accompanying drawings in which:
Referring to
A second layer 14 of pleated filter media having oppositely disposed facing surfaces in disposed in spaced relation downstream from the outer facing surface of the first layer 12. The pleated filter media is formed in an annular arrangement wherein the individual pleats are parallel with one another and are spaced apart in the same fashion as the pleats of the first layer 12.
The pleats of the second layer 14 are spaced from pleats in the first layer 12 by a fluid pervious pleated spacer material 16. The spacer material 16 provides a relatively void space between the first layer 12 and the second layer 14. It has been found that satisfactory functional results can be achieved by forming the spacer material 16 of a spacer material supplied by Nalle Plastic of Austin, Tex. and commercially designated as Naltex 37-3821.
A final fluid pervious pleated layer 18 is provided as a support media. The pleated layer 18 is formed of a woven screen material to provide and maintain the desired pleated configuration and to assure consistence of the separation of the pleats formed in the first layer 12, the second layer 14 and the spacer material 16. It has been found that a mesh size in the range of 15-30 mesh (wires/inch) is preferable in the pleated layer 18. Also, high open area (>40%) in the screen of the pleated layer 18 is preferable.
In the preferred embodiment of the invention, the first layer 12 of filter media is formed of a dual layer media which is constructed of two different glass fiber mixes incorporated into one thin unitary media to provide high dirt holding capacity. The second or downstream glass fiber mix contains finer or smaller diameter glass fibers in respect of the first glass fiber mix. The first glass fiber mix containing the more coarse fibers is effective to capture the larger particulate contaminants in the transient fuel being treated, while the second glass fiber mix containing the finer fibers is effective to capture the smaller particulate contaminants in the transient fuel being treated.
Functionally, it has been found that the first or upstream layer 12 functions to mainly capture solid particles, but the media also commences the coalescing process. Due to the stringent particle capacity requirements of such filter coalescer cartridges, the first layer 12 must exhibit very high particle loading capacity (high solids/area of media). Favorable results have been obtained employing a glass fiber media produced by Hollingsworth & Vose Company, East Walpole, Mass. and is commercially designated as DC-4271. The glass fiber is composed of borosilicate glass fibers with an acrylic binder. The acrylic binder content is about 5 by weight.
It has been found that as the first layer 12 captures particles from the transient fuel, the coalescing function of the layer 12 may tend to decrease in efficiency. As the first layer 12 captures more and more particles, the pores in the media become plugged with captured particulates. The velocity of the fluid flow through the remaining open pores tends to increase. Such increase in the velocity of the fluid being treated results in less efficient coalescing. Additionally, the free water in the transient fluid causes the pressure drop across the first layer 12 to rise which, in turn, impairs the coalescence of the water in the transient fluid.
The second layer 14 of filter media is effective to continue the water coalescence process as the fluid being treated passes through the cartridge. The second layer 14 is typically formed of the same filter media as the first layer 12.
The completed filter coalescer of the embodiment illustrated in
In order to obtain maximum burst strength, it has been found that the openings or perforations in the tube 20 are formed by stamping or otherwise producing louvered-like openings. The outermost surfaces of the radially outer pleats of the support layer 18 are positioned to be in intimate contact with the inner surface of the tube 20.
Next, a layer 22 of glass fiber material is wrapped about the outer surface of the perforated tube 20. The layer 22 is comprised of glass fiber wraps consisting of two media, clearly shown in
A layer 30 is formed about the outer surface of the support screen 28. The layer 30 is typically comprised of polyester fibers with a binder. The layer 24 is typically approximately ¼″ thick, and weighs 0.44 ounces per square foot. The material is commercially available under the trademark Hiloft from Hobbs Bonded Fibers, vendor P/N 63H515.
The entire cartridge assembly is disposed within an outer layer 32 formed of a knit material. The outer layer 32 may be formed of a cotton sock material 15 inches wide when fully stretched. The knit material includes metallic silver disposed thereon to provide anti-microbial properties to the outer layer 32. A satisfactory material typically is formed by weaving together a plurality of cotton threads, with some threads having at least one filament including metallic silver particles disposed thereon. Favorable results have been obtained by employing a plastic filament having metallic silver particles embedded thereon and spun with a plurality of cotton filaments to form a composite thread. The material is available commercially from Brecon Knitting Mill, Inc., Talladega, Ala. Additionally, a satisfactory material may have the following properties: 20 wales/inch, 20 courses/inch, and 12.5 yds/lb.
Functionally, it has been found that the metallic silver embedded in the cotton threads provides an anti-microbial property to the cotton outer layer 32. The metallic silver militates against microbes attaching to the cotton fibers, and extends the service life of the outer layer and the associated filter coalescer cartridge.
An alternative filter coalescer structure is illustrated in
The filter coalescer structure of
An outside or second pleat block 46 contains a layer 48 of pleated glass filter media having opposing disposed facing surfaces. The pleated fiber layer 48 is comprised of a dual layer media constructed of two different glass fiber mixes incorporated into one thin unitary media. The material is available from the same source as the layer 40. A fluid pervious woven mesh support media 50 is disposed in pleated relation on the outer facing surface of the filter layer 48.
A thin metal perforated tube 52, similar in construction to the tube 20 of the embodiment of
The completed filter coalescer of the embodiment illustrated in
Next, a layer 56 of fiberglass material is wrapped about the outer surface of the perforated tube 54. The layer 56 is comprised of a two media material including an inner wrap 58 and an outer wrap 60, clearly shown in
A layer 64 of material is formed about the outer surface of the support screen 62. The layer 64 is typically comprised of polyester fibers which is the same material used for forming the layer 30 of the embodiment of
The entire cartridge assembly is disposed within an outer layer 66 formed of a knit material which may be the same as used in forming the layer 32 of the embodiment of
Due to the extra space needed for the final layer 50 of support media compared with the embodiment illustrated in
An advantage of the embodiment of
The embodiment shown in
In accordance with the provisions of the patent statutes, the present invention has been described in what is considered to represent its preferred embodiment. However, it should be understood that the invention can be practiced otherwise than as specifically illustrated and described without departing from its spirit or scope.
