Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D39/00—Filtering material for liquid or gaseous fluids
  • B01D39/14—Other self-supporting filtering material ; Other filtering material
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D29/00—Filters with filtering elements stationary during filtration, e.g. pressure or suction filters, not covered by groups B01D24/00 - B01D27/00; Filtering elements therefor
  • B01D29/11—Filters with filtering elements stationary during filtration, e.g. pressure or suction filters, not covered by groups B01D24/00 - B01D27/00; Filtering elements therefor with bag, cage, hose, tube, sleeve or like filtering elements
  • B01D29/111—Making filtering elements
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D29/00—Filters with filtering elements stationary during filtration, e.g. pressure or suction filters, not covered by groups B01D24/00 - B01D27/00; Filtering elements therefor
  • B01D29/11—Filters with filtering elements stationary during filtration, e.g. pressure or suction filters, not covered by groups B01D24/00 - B01D27/00; Filtering elements therefor with bag, cage, hose, tube, sleeve or like filtering elements
  • B01D29/13—Supported filter elements
  • B01D29/15—Supported filter elements arranged for inward flow filtration
  • B01D29/21—Supported filter elements arranged for inward flow filtration with corrugated, folded or wound sheets
  • B01D29/216—Supported filter elements arranged for inward flow filtration with corrugated, folded or wound sheets with wound sheets
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D2201/00—Details relating to filtering apparatus
  • B01D2201/18—Filters characterised by the openings or pores
  • B01D2201/182—Filters characterised by the openings or pores for depth filtration
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D2201/00—Details relating to filtering apparatus
  • B01D2201/18—Filters characterised by the openings or pores
  • B01D2201/184—Special form, dimension of the openings, pores of the filtering elements

Definitions

• a process for making a filter cartridge comprising winding strand material in a crisscross pattern on a pervious core in a plurality of superposed layers with the strands in axially spaced relation and in substantially superposed position thereby forming circumferential series of diamond-shaped radial passages extending from the inner surface to the outer surface of said cartridge, the passages being progressively larger from said inner surface to said outer surface each of said series of diamond-shaped passages having substantially eight such passages per inch of internal diameter of the cartridge regardless of the degree of filtration expected from said cartridge and while winding applying a quantity of fibrous material on said strands and between the layers thereof to cause the fibrous material to lie on and be axially spaced by said strands and form within the passages filtering media, said fibrous material being determined by the desired degree of filtration expected from said cartridge.
• Filters of two general types related to the above are known. Generally, they are made by winding upon a pervious, that is, perforated or foraminous core or tube of metal or other suitable material, a roving or strand of textile material to make diamond-shaped apertures extending from the outside to the inside of the resulting cylindrical filter. These apertures are pyramidal in shape, that is, they have decreasing length as they progress toward the core from the outside circumference of the body of the filter. Consequently, the diamond-shaped apertures are smaller in length near the center of the completed filter.
• the roving or strand of textile material is napped, before winding, thereby producing fibers extending across the diamond-shaped openings.
• the napped fibers are supported only at one end, even where the diamond-shaped apertures are of small size and especially where they are largest.
• the density of the napped fibers depends upon the amount of material which can be napped or combed. It is the napped fibers which provide the filtering media and accordingly its density is also limited.
• the napped fibers must be of the same material as the roving employed.
• the disadvantages of the napped type of filter have been overcome, at least partially, by providing a filter in which the filtering media is applied separately, but simultaneously, with the roving while the roving is being wound on the supporting core.
• This permits the choice of a wider range of materials since the roving and filtering media need not be the same.
• the lengths of the inserted media can be varied at will, thereby providing lengths which can span one or more of the diamond-shaped apertures, if desirable.
• Such types of filters are also commercially employed in a wide variety of industrial applications.
• the diamond-shaped passages are made smaller so that the napped fibers are more numerous and give greater or more dense coverage of the diamond-shaped openings.
• this coverage is lost due to the inabilityof the napped fibers to efficiently cover a greater area.
• roving yarn which is more coarse is employed, it is difficult to wind into a diamond-shaped structure in which the diamonds are small enough to give a fine degree of filtration.
• the inability of the napped fibers to cover efficiently a good portion of the area in a diamond-shaped passage severely limits the size of a filter which can be so made.
• a typical one micron designated filter is wound with 39 diamonds spread circumferentially around an approximately 1 inch diameter center core.
• a typical 3micron filter has 27 diamonds so distributed, while a lO-micron filter uses 19 diamonds and a 20- micron filter uses 15 diamonds and so on, all using fewer diamonds as the degree of filtration becomes more coarse.
• the present practice also includes the use of interleaved winds where fine degrees of filtration are desired, rather than use of an ordinary open diamond. Consequently, this reduces area open to'flow, resulting in a corresponding penalty on flow capacity, as well as limited filter life.
• each layer of filter media is composed of a random layer of fibers across a diamondshaped opening between strands, with wide random variations in the density of each layer from point to point around the circumference and along the length and depth of each layer, a large number of diamonds will provide an averaging effect to help control the degree of filtration and atthe same time increase the useful life of such-filters by providing a bypass effect. Accordingly, as an individual diamond becomes plugged with dirt at varying depths in the cartridge, lateral flow will occur. Such lateral flow will then permit the fluid to pass through the yarn walls of the plugged diamond and into an adjacent diamond not yet filled with dirt.
• the present invention obviates the above listed disadvantages and provides improved diamond wound inserted media filter cartridges or napped matrix yarn with support filaments and a process for making the same and which have a flow capability increased by a factor of as much as eight or more and increased life as determined in a standard dust tester by a factor of two or more while at the same time the same degree of filtration is maintained and the cost of producing the filter is greatly reduced and wherein the number of diamonds spread circumferentially around the core is not more than eight per inch of internal diameter of the cartridges regardless of the degree of filtration which is expected from the cartridges, this last factor being controlled by insertion of media of sufficient web strength for the particular degree of filtration or rating desirable or sufficient support fibers inserted where a napped matrix and no inserted media is used.
• support yarns which are used for the diamond-shaped winding.
• It can be natural or synthetic material or glass or metal.
• it may be a single, large diameter monofilament yarn or it can be made of many crimped staple monofilaments formed into a yarn.
• it may be tubular or of any cross-sectional design.
• it may have ridge or other surface characteristics to improve its ability to clamp or hold the inserted media fibers. Its only necessary physical characteristics are sufficient flexibility and tensile strength to permit winding and sufficient cross-sectional area to effect separation of the various layers of filter media inserted in the winding.
• the napped fibers do not function as filter media but rather as reinforcements for the filter media or act to mechanically en tangle the filter media.
• the napped yarn acts as the filter media as well, where no inserted media web is employed. It is to be noted, however, that regardless of what particular type of material is used or what its particular physical construction is like, the yarn or roving which forms the body of the filter is only a structural skeleton which does not contribute to the filtering characteristics of the final cartridge.
• the yarn or roving since the yarn or roving is used to form the diamond-shaped support structure, it should be wound in the largest diamond shape possible and the number of diamonds should never exceed eight per inch of internal diameter of the cartridge and can be as small as two and even one so long as it is possible to form one diamond per inch of internal diameter of the cartridge.
• the inserted media may also vary widely in choice of material and properties, it being only necessary that it have sufficient strength to withstand the required use.
• Web strength is a function of radial location, filament strength and fiber length as well as the amount of media used and the manner in which it is deposited and in which it is supported. Consequently, the media itself may be chosen from the wide variety of materials mentioned above for use as the support yarn, except it will only be metal or glass in very special cases where particular requirements may specifically call for it.
• it may be the same material or the support yarn or it may be different. It also can be a napped yarn.
• staple fibers are employed, they should be of sufficient length to span the center to center distance of two adjacent diamonds at the point of maximum diamond length at a diameter 0.25 inch greater than that diameter at which the first insertion of media was made.
• staple lengths of media equivalent to one diamond length plus 0.2 inch are also satisfactory from a strength standpoint although wider tolerances on maintaining the degree of filtration result.
• the filter cartridges of this invention also have a graduated decreasing density exhibited by the filter media as the diameter of the cartridge increases. This is brought about by attenuation of inserted media as explained more fully hereinafter. Moreover, as the diamond size of the structural matrix increases and the staple length of inserted media is no longer sufiicient to span the diamond-shaped openings. Some of the fibers in the inserted media become cantilevered out from the structural matrix providing a cartridge which exhibits true depth filtration.
• the filter media bed can be inserted from the beginning of the wind, it is preferred that the bed extend from the first complete layer of diamonds and most preferred that it extend at least from a point smaller in diameter than the diameter of the seals normally used to close up the ends of a filter when it is in service.
• the smallest diameter seals generally used on a standard industrial cartridge with a one inch inside diameter core is 1.5 inches in diameter. Since a minimum depth of about A; is needed to build an adequate filter bed ahead of the minimum diameter seal plate used, media is inserted starting at about 1.25 inches in diameter.
• This diameter should, however, be maximized since it provides a hydraulic cushion between the actual filtering layer and the perforated core, thereby minimizing the velocity effects of flow as the flow velocity increases to exit through the perforations in the core.
• the span across any diamond is still relatively small even in filters having eight diamonds or less and media fibers are available which in a minimum inch thick bed will support flow and remain intact while allowing some flow at differential pressures up to 55 pounds per square inch.
• Such support fibers may also be used when employing short staple media fibers where staple length is not materially changed by attenuation or with some natural staple fibers or when the diamond openings increase in size as the diameter increases where making thick wall cartridges.
• bonding adhesives where compatible with intended use can be sprayed or roller coated on the filter media web to further strengthen and fix the filter bed.
• heated rolls either plain or patterned can be employed to fuse together the filter media fibers, as well as the structural strand reinforcing strands where they are employed.
• the process for making the filters of this invention is relatively simple in nature.
• the desired winding pattern of not more than eight diamonds per inch of internal diameter of the filter can be carried out on any standard winding machine.
• the inserted media and/or media and support yarns is fed through a standard textile draw frame and to the winding being formed by the structural yarns after passing between a pair of power driven rolls conveniently located adjacent the winding machine.
• One of more cartridges may be wound at the same time. Different densities can be attained simply by changing the speed of the media feed.
• Attenuation Even though some attenuation takes place as the winding and insertion of media progresses and the cartridge becomes larger, it is preferred that the material being inserted be positively drawn before insertion unless already in a drawn state. Generally, attenuation varies widely and is at least sufficient so that the resulting attenuated fibrous material forms a thin web of high porosity fibrous media. For example, using a corded lap of 600 grains per linear yard of a inch width attenuation by a factor of approximately 8 to l is accomplished to provide a satisfactory web before the media is inserted. Any particular draw ratio is simply accomplished by changing the speed of the rolls on the draw frame.
• a complete line of filters can be made by employing a constant winding speed while varying the media or fibrous material feed rate over a range of to 1.
• the process of this invention broadly comprises winding strand material in a crisscross pattern on a pervious core on a plurality of superposed layers, the strands being in axially spaced relation and forming a series of progressively larger diamond shaped radial passages extending from the inner surface to the outer surface of the cartridge, the number of diamonds so wound per inch of internal diameter being not more than eight. While such winding is taking place the fibrous media material is applied in desirable quantity on said strands and between layers thereof so that it lies thereon and forms a filtering surface. As pointed out hereinbefore, the fibrous material can be attenuated before being inserted into the strand material as it is wound. Moreover, where desirable the strand material can be napped prior to winding or likewise the fibrous material can be napped before being inserted.
• introduction of the inserted fibrous media is not commenced until the strand material is wound for at least several revolutions.
• the purpose of this is to supply a hydraulic cushion between the actual filtering layer and the perforated core to minimize the velocity effects of flow as the flow velocity increases to exit through the perforations in the center core.
• the improved filter cartridges of this invention and the process of their manufacture present numerous advantages.
• the cartridges have more open area thereby permitting more flow and longer useful life.
• the flexibility of the process permits the utilization of a wide variety of materials which allows the insertion of strongly filter media, thereby supplying strongly filter beds in an open type cartridge. Numerous other advantages of the cartridges and the process for their manufacture according to the invention will be apparent.
• the process of this invention permits the manufacture of a complete line of filter cartridges from those which have the ability to filter fine materials to those which have the ability to filter relatively coarse material with relatively no change in the process except by merely increasing or decreasing the said rate at which the fibrous media is inserted.
• the cartridges of this invention In order to illustrate the improvements attained by the cartridges of this invention the following comparative data is set forth. in obtaining this data three types of cartridges were employed. All of the cartridges were made from rayon windings and rayon media, the cartridge designated by numeral one in the following table was a 27 diamond wind having inserted discrete fibrous media inserted therein. The cartridge designated by numeral two is a 27 diamond wind cartridge made from napped rayon winding and the cartridge designated by numeral 3 is the new and improved 8 diamond wind cartridge of this invention wherein fibrous rayon media was inserted to provide a filtering bed.
• Test results as shown in the accompanying table were run on the basis of measured flow in gallons per minute at 2 psi. differential pressure for cartridges of the same degree of filtration. Life test consisted of flowing 3 gallons per minute of water contaminated with a fixed amount of Arizona coarse test dust. In all cases this flow was maintained until a differential pressure of 20 p.s.i. was reached. The figures shown in the table are the total weight of the test dust needed to TABLE Continued.
• a process for making a filter cartridge comprising winding strand material in a crisscrow pattern on a pervious core in a plurality of superposed layers with the strands in axially spaced relation and in substantially superposed position thereby forming circumferential series of diamond-shaped radial passages extending from the inner surface to the outer surface of said cartridge, the passages being progressively larger from said inner surface to said outer surface, each of said series of diamond-shaped passages having substantially eight such passages per inch of internal diameter of the cartridge regardless of the degree of filtration expected from said cartridge and while winding applying a quantity of fibrous material on said strands and between the layers thereof to cause the fibrous material to lie on and be axially spaced by said strands and form within the passages filtering media, said fibrous materialbeing determined by the desired degree of filtration expected from said cartridge.

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• Chemical & Material Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Filtering Materials (AREA)

Applications Claiming Priority (1)

Publications (1)

Family

ID=25245333

Family Applications (1)

Country Status (7)

Cited By (8)

Families Citing this family (1)

Citations (2)

• 1969
  • 1969-05-19 US US825964A patent/US3648846A/en not_active Expired - Lifetime
  • 1969-10-14 GB GB50491/69A patent/GB1261820A/en not_active Expired
  • 1969-10-23 NL NL6916036A patent/NL6916036A/xx unknown
  • 1969-11-03 BR BR213861/69A patent/BR6913861D0/pt unknown
  • 1969-11-28 FR FR6941147A patent/FR2046060A5/fr not_active Expired
• 1970
  • 1970-01-14 DE DE2001509A patent/DE2001509C3/de not_active Expired
  • 1970-01-16 BE BE744518D patent/BE744518A/xx unknown

Patent Citations (2)

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