CA1166974A - Filter bag and method for suppressing electrostatic charges - Google Patents
Filter bag and method for suppressing electrostatic chargesInfo
- Publication number
- CA1166974A CA1166974A CA000399697A CA399697A CA1166974A CA 1166974 A CA1166974 A CA 1166974A CA 000399697 A CA000399697 A CA 000399697A CA 399697 A CA399697 A CA 399697A CA 1166974 A CA1166974 A CA 1166974A
- Authority
- CA
- Canada
- Prior art keywords
- electrically conductive
- yarn
- bag
- strand
- fabric
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
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- Filtering Materials (AREA)
Abstract
FILTER BAG AND METHOD FOR SUPPRESSING
ELECTROSTATIC CHARGES
Abstract of the Invention A fabric filter bag, a method of making such a bag, and apparatus using such bags, in which the bag is a tube of yarn knit into stitches defining a ground and stitches defining terry loop pile extending from the ground. In accordance with the present invention, such a fabric filter bag, method of making a bag r and apparatus using a bag is improved by the inclusion of a conductive strand for conducting electrostatic charges otherwise accumu-lating on the fabric filter bag away from the bag so as to suppress accumulation or build-up of such charges.
ELECTROSTATIC CHARGES
Abstract of the Invention A fabric filter bag, a method of making such a bag, and apparatus using such bags, in which the bag is a tube of yarn knit into stitches defining a ground and stitches defining terry loop pile extending from the ground. In accordance with the present invention, such a fabric filter bag, method of making a bag r and apparatus using a bag is improved by the inclusion of a conductive strand for conducting electrostatic charges otherwise accumu-lating on the fabric filter bag away from the bag so as to suppress accumulation or build-up of such charges.
Description
s~
FILTE~ BAG AND METHOD FOR SUPPRESSING
ELECTROSTATIC CHARGES
Field and Back~round of Invention Bag ~ er apparatus and fabric filter bags used in such apparatus have been employed for some time for separating particulate material from fluids.
One generally known use for such bag filter apparatus and fabric filter bags is in the field of handling grain and grain products such as flour and mealO
Fabrics have been manufactured for speci~ic use as fabric rilter bags in suc~ fiel~sr in order that separatiGn of solid particulate material from air~
- 10 gas and the like may be accomplished. Persons fami-liar with the field of ~iltration generally will be aware of other uses for such fabrics, filter bags and filter bag apparatus.
~articularly in certain applications for such apparatus~ bags an~ fabrics, a significant risk is presented by the accumulation or build-up of electrostatic charges in the filtering process.
Certain fluids and/or particulate substances to be removed from the fluids are or can become explosive.
For example, wheat 1O-Ir being separated from air streams can, under proper circumstances~ become explosive. Further, friction involved in such ~iltration frequently gives rise to electrostatic charges which occur or appear on components of a ~i~ker apparatus. Whexe an explosive or potentially explosive material i5 being ~iltered in an apparatus 3. ~
and throu~h tl-e use of bags and fabrics which accumu-late electrostatic charyes, explosions are possible which are capable of doing severe dama~e to apparatus involved and, in certain circumstances, killing per-sons employed in the area of the filter apparatus.Brief Description of Invention Reali~ing the diff iculties and deficiencies with prior filter apparatus, bags and fabrics, it is an object of the present invention to improve such structures by providing for suppressing accumulation or build-up of electrostatic charges. In realizing this object of the present invention, electrostatic charges are conducted ~rom the fabric filter bags employed~ so as to prevent or suppress accumulation or build-up of such chargesO Inasmuch as such charges are suppressed or drained away, the potential of spark ignition of an explosive mixture i5 signifi-cantly reduced or is eliminated altogether~
Y~ a further o~ect o the present inven tion is to accomplish, in a method of making fabric ~ filter ~ags, an improvement which facilitates safely discharging electrostatic charges otherwise possibly accumulating on fabric filter bags during filtration use~ In realizing this object of the present inven-~5 tion, an electrically conductive strand is knitted with filamentary yarn used in forming a filter ~abric. In accordance with certain features o~ this invention, such an electrically conductive strand takes the form of a synthetic monofilament yarn having electrically conductive characteristics, while in accordance with other aspects of this invention such an electrically conductive strand comprises a metallic staple yarn. In a preferred form, the method includes knitting yarn having a predetermined denier into a tube of predetermined diameter and at ~3--least a predetermined length while forminy the yarn into stitches deFining a ground and stitches defining terry loop pile extending from the ground to a prede termined height, the stitches defining predetermined open areas in the fabric, and an improvement which ~acilitates safely discharging electrostatic charges otherwise accumulating on the fabric filter bags during filtration use, the improvement comprising the step of knitting with the yarn an electrically con-ductive strand.
Yet a further object of the presen~ inven-tion is to provide, in a bag ilter apparatus having a fabric bag which comprises a tube of circularly knitted, crimped, synthetic filamentary yarn knit into stitches defining a ground and stitches defining terry loop pile extending from the ground, a conduc~
tive strand formed with the stitches defining terry loop pile and ~unctioning to conduct from the bag electrostatic charges otherwise possibly accumulating ~0 thereon. A pre~erred form of the invention is in a - kag filter apparatus having a fabric bag for filtering makerial froln the flowing fluid, housing means for enclosing and supporting said bag, and cir-culating means including inlet and outlet means for directing a flow of fluid through said housing means and said bag, the bag comprising a tube of yarn having a predetermined denier and knit into stitches defining a ground and stitches defining terry loop pile extending from the ground to a predetermined height, the stitches defining predetermined open areas in the fabric, an improvement which facilitates safely discharging electrostatic charges otherwise accumulating on the fabric filter bag during filtra-tion use, the improvement comprising an electrically 9 ~ ~
o~
conductive strand knitted witll the yarn for con ducting from the bag electrostatic charges otherwise accumulating thereon.
Brief Descri t.5~ 9-~
Some of the objects of the invention having been stated, other objects will appear as the description proceeds, when taken in connection with the accompanying drawings, in which -~
Figure 1 is an elevation vlew of a fabric filter bag embodying the present invention;
Figure 2 is an enlarged elevation view of a portion of ~he bag of Fi.gure 1, taken generally as indicated in that Figure;
Figure 3 is a schematic representation of the knit stitch structure of the fabric of Figures 1 and 2, particularly showing an electrically conduc-tive strand incorporated into the fabric and bag in accordance with the present invention;
Figure 4 is a perspecti.ve view, from a ground abric side, of the fabric of Figures 1 and 2;
- Figure 5 is a view similar to Figure 4, from the pile face of the fabric of Figures 1 and 2;
and E'igure 6 is a perspective view, partly bro-ken away, of a bag filter apparatus incorporating afilter in accordance with the present invention.
Detailed Description of Invention While the present invention will be described hereinafter with particular re~erence to the accompanying drawings, it is to be understood at the outset that persons skilled in the applicable arts will be able to modify the pxesent invention while accomplishing the ~avorable result to be described. Accordingly, the following description is to be understood, from the outse~, as a broad teaching disclosure directed to persons skilled in 59~
the art, and not as being restrictive upon the scope of this invention~
Referring now more particularly to the accompanying dxawings, a fabric Eilter bag is shown in Figure 1 and is there generally indicated at 10.
~he fabric filter bag in accordance with the present invention, comprises a tube of yarn having a prede-~ermined denier and knit into stitches defining a ground and stitches defining terry loop pile extending from the ground to a predetermined height.
The stitches of the fabric formillg the tube define predetermined open areasc The fabric filter bag is useful in apparatus ~Figure 6) having housing means 11 for enclosing and supporting the bag and cir-culating means including fan means 12 or the like andinlet and outlet means for directing a flow of fluid through the housing means and the bag so as to remove particulate material from the flowing fluid. Such structures are generally known to persons skilled in the arts to which the present invention pertains and specific details of such structures may be readily determined from known prior publications.
Preferably, the tube is circulaxly ~nit of crimped, synthetic filamentary yarn. Specific ranges for the denier of the crimped synthetic filamentary yarn, the porosity of the filter ~laterial as determined by the stitch s~ructure, and the height of the terry loops may be determined by persons skilled in the appropriate arts. For example, the fabric may be ~ormed with filamentary yarn of one hundred denier kn~t into stitches defining terry loop pile extending approximately two millimeters from a ground and having a porosity such as to pass particles of fifty micron size or less.
In accordance with the present invention, 8uch a fabric filter bag 10 and apparatus using such ~a bag is improved by a provision of means for con-ducting eleetrostatic charges from the fabric filter bag. More particularly, the fabric filter bag in-cludes an electrically conductive strand, as indi-S cate~ in Figures 1 and 2~ Preferably, theelectrically conductive strand 15 i5 knitted with the filamentary yarn forming a pile, as indicated generally in Figures 3 through 5. In the schematic representation of Figure 3, the electrically conduc-tive strand 15 is indicated by darker shading than isthe ca~e for the ~ilamentary yarn. Simi]arly, in the fabric views of Figures 4 and 5, the conductive strand 15 is knitted with a filamentary yarn ~orminy pile.
One operating embodiment in accordance with the present invention was constructed in accordance with a method in which an electrically conductive strand 15 was knitted with the filamentary yarn forming the fabric~ In particular, the electrically conductive strand was fed to an eight feed knitting machine together with a crimped, synthetic filamen-tary yarn so as to form the strand and the yarn together into the stitches defining terry loop pile as shown in Figures 3 through 5. In one embodiment in accordance with this inventioll, a synthetic mono-filament yarn havins electricaliy conductive charac~
teristics due to the inclusion of conductive materials in the yarn was employed as the conductive strand. The present invention additionally con-templates that the electrically conductive strand maycomprise a metallic staple yarn, fed into the knitting machine with a ~ynthetic filamentary yarn.
Such a metallic staple yarn may be formed using rela-tively short lengths of metallic strands, and will perform the conductive function required in accor-dance with the present invention. The electrically 6~97d ~7--conductive strand may also be fsrmed by lamination with vacuum metalized foils.
Where the fabric filter bag 10 is manufac-tured as a seamless bagt using a circular knitting 5 machinel the electrically conductive strand 15 is knitted into courses of tle fabric so as to extend essentially continuously throughout the length of the bag and spiral about the circumference thereof~
Thus, electrostatic charges otherwise accumulating at 1~ any point on the surface of the bag are conducted through the yarn to a portion of the bag gripped by mounting means which holds the bag in place during use in a filtering apparatus. Where the fabric is formed in a larger diameter which is then slit, opened and sewn into a bagl similar conductance of electrostatic charges to a ground point in the apparatus may be accomplished by seaming the bag with an electrically conductive strand of the same general type knitted into the ~abric. In either instance, the risks associated with sparking from accumulated -- electrostatic charges are eliminatedO
In the drawings and specification, there has been set forth a preferred embodiment of the inv~ntion, and although specific terms are employed, they are used in a generic and descriptive sense only and not for purposes of limitation.
FILTE~ BAG AND METHOD FOR SUPPRESSING
ELECTROSTATIC CHARGES
Field and Back~round of Invention Bag ~ er apparatus and fabric filter bags used in such apparatus have been employed for some time for separating particulate material from fluids.
One generally known use for such bag filter apparatus and fabric filter bags is in the field of handling grain and grain products such as flour and mealO
Fabrics have been manufactured for speci~ic use as fabric rilter bags in suc~ fiel~sr in order that separatiGn of solid particulate material from air~
- 10 gas and the like may be accomplished. Persons fami-liar with the field of ~iltration generally will be aware of other uses for such fabrics, filter bags and filter bag apparatus.
~articularly in certain applications for such apparatus~ bags an~ fabrics, a significant risk is presented by the accumulation or build-up of electrostatic charges in the filtering process.
Certain fluids and/or particulate substances to be removed from the fluids are or can become explosive.
For example, wheat 1O-Ir being separated from air streams can, under proper circumstances~ become explosive. Further, friction involved in such ~iltration frequently gives rise to electrostatic charges which occur or appear on components of a ~i~ker apparatus. Whexe an explosive or potentially explosive material i5 being ~iltered in an apparatus 3. ~
and throu~h tl-e use of bags and fabrics which accumu-late electrostatic charyes, explosions are possible which are capable of doing severe dama~e to apparatus involved and, in certain circumstances, killing per-sons employed in the area of the filter apparatus.Brief Description of Invention Reali~ing the diff iculties and deficiencies with prior filter apparatus, bags and fabrics, it is an object of the present invention to improve such structures by providing for suppressing accumulation or build-up of electrostatic charges. In realizing this object of the present invention, electrostatic charges are conducted ~rom the fabric filter bags employed~ so as to prevent or suppress accumulation or build-up of such chargesO Inasmuch as such charges are suppressed or drained away, the potential of spark ignition of an explosive mixture i5 signifi-cantly reduced or is eliminated altogether~
Y~ a further o~ect o the present inven tion is to accomplish, in a method of making fabric ~ filter ~ags, an improvement which facilitates safely discharging electrostatic charges otherwise possibly accumulating on fabric filter bags during filtration use~ In realizing this object of the present inven-~5 tion, an electrically conductive strand is knitted with filamentary yarn used in forming a filter ~abric. In accordance with certain features o~ this invention, such an electrically conductive strand takes the form of a synthetic monofilament yarn having electrically conductive characteristics, while in accordance with other aspects of this invention such an electrically conductive strand comprises a metallic staple yarn. In a preferred form, the method includes knitting yarn having a predetermined denier into a tube of predetermined diameter and at ~3--least a predetermined length while forminy the yarn into stitches deFining a ground and stitches defining terry loop pile extending from the ground to a prede termined height, the stitches defining predetermined open areas in the fabric, and an improvement which ~acilitates safely discharging electrostatic charges otherwise accumulating on the fabric filter bags during filtration use, the improvement comprising the step of knitting with the yarn an electrically con-ductive strand.
Yet a further object of the presen~ inven-tion is to provide, in a bag ilter apparatus having a fabric bag which comprises a tube of circularly knitted, crimped, synthetic filamentary yarn knit into stitches defining a ground and stitches defining terry loop pile extending from the ground, a conduc~
tive strand formed with the stitches defining terry loop pile and ~unctioning to conduct from the bag electrostatic charges otherwise possibly accumulating ~0 thereon. A pre~erred form of the invention is in a - kag filter apparatus having a fabric bag for filtering makerial froln the flowing fluid, housing means for enclosing and supporting said bag, and cir-culating means including inlet and outlet means for directing a flow of fluid through said housing means and said bag, the bag comprising a tube of yarn having a predetermined denier and knit into stitches defining a ground and stitches defining terry loop pile extending from the ground to a predetermined height, the stitches defining predetermined open areas in the fabric, an improvement which facilitates safely discharging electrostatic charges otherwise accumulating on the fabric filter bag during filtra-tion use, the improvement comprising an electrically 9 ~ ~
o~
conductive strand knitted witll the yarn for con ducting from the bag electrostatic charges otherwise accumulating thereon.
Brief Descri t.5~ 9-~
Some of the objects of the invention having been stated, other objects will appear as the description proceeds, when taken in connection with the accompanying drawings, in which -~
Figure 1 is an elevation vlew of a fabric filter bag embodying the present invention;
Figure 2 is an enlarged elevation view of a portion of ~he bag of Fi.gure 1, taken generally as indicated in that Figure;
Figure 3 is a schematic representation of the knit stitch structure of the fabric of Figures 1 and 2, particularly showing an electrically conduc-tive strand incorporated into the fabric and bag in accordance with the present invention;
Figure 4 is a perspecti.ve view, from a ground abric side, of the fabric of Figures 1 and 2;
- Figure 5 is a view similar to Figure 4, from the pile face of the fabric of Figures 1 and 2;
and E'igure 6 is a perspective view, partly bro-ken away, of a bag filter apparatus incorporating afilter in accordance with the present invention.
Detailed Description of Invention While the present invention will be described hereinafter with particular re~erence to the accompanying drawings, it is to be understood at the outset that persons skilled in the applicable arts will be able to modify the pxesent invention while accomplishing the ~avorable result to be described. Accordingly, the following description is to be understood, from the outse~, as a broad teaching disclosure directed to persons skilled in 59~
the art, and not as being restrictive upon the scope of this invention~
Referring now more particularly to the accompanying dxawings, a fabric Eilter bag is shown in Figure 1 and is there generally indicated at 10.
~he fabric filter bag in accordance with the present invention, comprises a tube of yarn having a prede-~ermined denier and knit into stitches defining a ground and stitches defining terry loop pile extending from the ground to a predetermined height.
The stitches of the fabric formillg the tube define predetermined open areasc The fabric filter bag is useful in apparatus ~Figure 6) having housing means 11 for enclosing and supporting the bag and cir-culating means including fan means 12 or the like andinlet and outlet means for directing a flow of fluid through the housing means and the bag so as to remove particulate material from the flowing fluid. Such structures are generally known to persons skilled in the arts to which the present invention pertains and specific details of such structures may be readily determined from known prior publications.
Preferably, the tube is circulaxly ~nit of crimped, synthetic filamentary yarn. Specific ranges for the denier of the crimped synthetic filamentary yarn, the porosity of the filter ~laterial as determined by the stitch s~ructure, and the height of the terry loops may be determined by persons skilled in the appropriate arts. For example, the fabric may be ~ormed with filamentary yarn of one hundred denier kn~t into stitches defining terry loop pile extending approximately two millimeters from a ground and having a porosity such as to pass particles of fifty micron size or less.
In accordance with the present invention, 8uch a fabric filter bag 10 and apparatus using such ~a bag is improved by a provision of means for con-ducting eleetrostatic charges from the fabric filter bag. More particularly, the fabric filter bag in-cludes an electrically conductive strand, as indi-S cate~ in Figures 1 and 2~ Preferably, theelectrically conductive strand 15 i5 knitted with the filamentary yarn forming a pile, as indicated generally in Figures 3 through 5. In the schematic representation of Figure 3, the electrically conduc-tive strand 15 is indicated by darker shading than isthe ca~e for the ~ilamentary yarn. Simi]arly, in the fabric views of Figures 4 and 5, the conductive strand 15 is knitted with a filamentary yarn ~orminy pile.
One operating embodiment in accordance with the present invention was constructed in accordance with a method in which an electrically conductive strand 15 was knitted with the filamentary yarn forming the fabric~ In particular, the electrically conductive strand was fed to an eight feed knitting machine together with a crimped, synthetic filamen-tary yarn so as to form the strand and the yarn together into the stitches defining terry loop pile as shown in Figures 3 through 5. In one embodiment in accordance with this inventioll, a synthetic mono-filament yarn havins electricaliy conductive charac~
teristics due to the inclusion of conductive materials in the yarn was employed as the conductive strand. The present invention additionally con-templates that the electrically conductive strand maycomprise a metallic staple yarn, fed into the knitting machine with a ~ynthetic filamentary yarn.
Such a metallic staple yarn may be formed using rela-tively short lengths of metallic strands, and will perform the conductive function required in accor-dance with the present invention. The electrically 6~97d ~7--conductive strand may also be fsrmed by lamination with vacuum metalized foils.
Where the fabric filter bag 10 is manufac-tured as a seamless bagt using a circular knitting 5 machinel the electrically conductive strand 15 is knitted into courses of tle fabric so as to extend essentially continuously throughout the length of the bag and spiral about the circumference thereof~
Thus, electrostatic charges otherwise accumulating at 1~ any point on the surface of the bag are conducted through the yarn to a portion of the bag gripped by mounting means which holds the bag in place during use in a filtering apparatus. Where the fabric is formed in a larger diameter which is then slit, opened and sewn into a bagl similar conductance of electrostatic charges to a ground point in the apparatus may be accomplished by seaming the bag with an electrically conductive strand of the same general type knitted into the ~abric. In either instance, the risks associated with sparking from accumulated -- electrostatic charges are eliminatedO
In the drawings and specification, there has been set forth a preferred embodiment of the inv~ntion, and although specific terms are employed, they are used in a generic and descriptive sense only and not for purposes of limitation.
Claims (12)
1. In a method of making fabric filter bags which includes knitting yarn having a predeter-mined denier into a tube of predetermined diameter and at least a predetermined length while forming the yarn into stitches defining a ground and stitches defining terry loop pile extending from the ground to a predetermined height, the stitches defining prede-termined open areas in the fabric, an improvement which facilitates safely discharging electrostatic charges otherwise accumulating on the fabric filter bags during filtration use, the improvement comprising the step of knitting with the yarn an electrically conductive strand.
2, A method according to Claim 1 wherein the step of knitting an electrically conductive strand comprises feeding the electrically conductive strand with a yarn while forming the strand and the yarn into the stitches defining terry loop pile.
3. A method according to one of Claims 1 and 2 wherein the step of knitting an electrically conductive strand comprises feeding with a yarn a synthetic monofilament strand having electrically conductive characteristics.
4. A method according to one of Claims 1 and 2 wherein the step of knitting an electrically conductive strand comprises feeding with a yarn a metallic staple strand.
5. In a fabric filter bag comprising a tube of yarn having a predetermined denier and knit into stitches defining a ground and stitches defining terry loop pile extending from the ground to a prede-termined height, the stitches defining predetermined open areas in the fabric, an improvement which faci-litates safely discharging electrostatic charges otherwise accumulating on the fabric filter bag during filtration use, the improvement comprising an electrically conductive strand knitted with the yarn for conducting electrostatic charges from the fabric filter bag.
6. A fabric filter bag according to Claim 5 wherein the electrically conductive strand is knitted with a yarn into the stitches defining terry loop pile.
7. A fabric filter bag according to one of Claims 5 and 6 wherein the electrically conductive strand is a synthetic monofilament strand having electrically conductive characteristics.
8. A fabric filter bag according to one of Claims 5 and 6 wherein the electrically conductive strand is a metallic staple strand.
9. In a bag filter apparatus having a fabric bag for filtering material from the flowing fluid, housing means for enclosing and supporting said bag, and circulating means including inlet and outlet means for directing a flow of fluid through said housing means and said bag, the bag comprising a tube of yarn having a predetermined denier and knit into stitches defining a ground and stitches defining terry loop pile extending from the ground to a prede-termined height, the stitches defining predetermined open areas in the fabric, an improvement which faci-litates safely discharging electrostatic charges otherwise accumulating on the fabric filter bag during filtration use, the improvement comprising an electrically conductive strand knitted with the yarn for conducting from the bag electrostatic charges otherwise accumulating thereon.
10. An apparatus according to Claim 9 wherein the electrically conductive strand is knitted with a yarn into the stitches defining terry loop pile.
11. An apparatus according to one of Claims 9 and 10 wherein the electrically conductive strand is a synthetic monofilament strand having electrically conductive characteristics.
12. An apparatus according to one of Claims 9 and 10 wherein the electrically conductive strand is a metallic staple strand.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000399697A CA1166974A (en) | 1982-03-29 | 1982-03-29 | Filter bag and method for suppressing electrostatic charges |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000399697A CA1166974A (en) | 1982-03-29 | 1982-03-29 | Filter bag and method for suppressing electrostatic charges |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1166974A true CA1166974A (en) | 1984-05-08 |
Family
ID=4122439
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000399697A Expired CA1166974A (en) | 1982-03-29 | 1982-03-29 | Filter bag and method for suppressing electrostatic charges |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1166974A (en) |
-
1982
- 1982-03-29 CA CA000399697A patent/CA1166974A/en not_active Expired
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |