CA2421334A1 - Flexible duct system - Google Patents
Flexible duct system Download PDFInfo
- Publication number
- CA2421334A1 CA2421334A1 CA 2421334 CA2421334A CA2421334A1 CA 2421334 A1 CA2421334 A1 CA 2421334A1 CA 2421334 CA2421334 CA 2421334 CA 2421334 A CA2421334 A CA 2421334A CA 2421334 A1 CA2421334 A1 CA 2421334A1
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- Prior art keywords
- duct
- duct section
- bell
- spigot
- section
- 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.)
- Abandoned
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Classifications
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F24—HEATING; RANGES; VENTILATING
- F24F—AIR-CONDITIONING; AIR-HUMIDIFICATION; VENTILATION; USE OF AIR CURRENTS FOR SCREENING
- F24F13/00—Details common to, or for air-conditioning, air-humidification, ventilation or use of air currents for screening
- F24F13/02—Ducting arrangements
- F24F13/0254—Ducting arrangements characterised by their mounting means, e.g. supports
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F24—HEATING; RANGES; VENTILATING
- F24F—AIR-CONDITIONING; AIR-HUMIDIFICATION; VENTILATION; USE OF AIR CURRENTS FOR SCREENING
- F24F13/00—Details common to, or for air-conditioning, air-humidification, ventilation or use of air currents for screening
- F24F13/02—Ducting arrangements
- F24F13/0218—Flexible soft ducts, e.g. ducts made of permeable textiles
Abstract
A flexible ventilation duct system comprising a bell-and-spigot arrangement, whereby a spigot end of one duct section is inserted into a bell end of a next adjacent duct section, such that when the duct is inflated the spigot expands against the bell to form a substantially air-tight seal. In the preferred embodiment sections of ducting are connected together by clips that are permanently attached to one section of ducting to facilitate quicker duct installation and removal, and ensure effective connection between sections.
Description
FLEXIBLE DUCT SYSTEM
Field of the Invention This invention relates to flexible ducting. In particular, this invention relates to flexible ventilation ducting such as that used in the mining industry, in which duct sections are joined together to provide fresh air into a mine and to remove gases from within the mine.
Background of the Invention For decades, underground mines around the world have been using flexible ducting in lay-flat and spiral reinforced configurations (typically having diameters from 6 inches to over 120 inches), which are attached to high-pressure fans to provide ventilation within the mine. As mine headings advance, sections of duct, typically consisting of lengths from 25 feet to over 50 feet, are added to maintain air delivery to the working face of the heading. This is necessary to provide fresh air to miners working at these locations and to remove noxious gases generated by blasting and mining equipment.
Prior art flexible duct systems include ducts in which adjacent sections of ducting are connected to one another by clips or other similar attachment devices that are not permanently attached to the ducting. The clips used on prior art duct systems often fall off at fan start up or during blasting, or may be knocked off by passing equipment. Often such fallen clips become lost in the muck pile. Accordingly, the clips used in prior art duct systems frequently have to be replaced.
The clips used on prior art duct systems can also tear and otherwise damage the duct material during installation and removal of the duct system.
The significant manpower costs incurred when installing and removing prior art ducting is thus exacerbated by costs associated with repairs and system maintenance.
Further, the joints between adjacent sections of prior art ducting are sealed by connectors, clamps or other sealing devices in an attempt to minimize joint leakage. Often vent clips such as "mufti-clips" or connecting couplers are used. These are separate clips which must be attached to both adjoining duct sections at the rime of installation, which is time consuming. Typical installation errors associated with such prior art duct systems include incorrectly installing the clips, installing clips at the wrong location about the end of a duct section, installing too few clips to adequately connect adjacent duet sections, or incorrectly putting the ducting end rings together. Such errors result in leakage between adjacent duct sections, and occasionally failure of the duct under the high pressure of the ventilation fari.
The use of mufti-clips also often results in bunching of the duct tubing at the joints. Such bunching increases air resistance within the tubing, thus placing more energy demands on the ventilation fan.
Also, with conventional duct ventilation systems, the ducting is suspended by suspending clips colloquially known as "paper clips," which are bent or coiled pieces of wire that attach to a messenger cable or screen that runs along the tunnel and suspends the assembled ducting. A problem with such clips is that during installation, the installer must lift the ducting up to the messenger cable or screen and then twist the ducting to clip it on to the messenger cable. This is very time consuming.
Moreover, when removing the ducting, the suspending clips are difficult to undo and often the operator may just rip down the ducting and therefore tear the duct wall, rendering it in need of repair or useless. Also, such suspending clips are not as sturdy as is desirable in a mining environment.
Summary of the Invention The present invention addresses the above-mentioned problems of the prior art flexible ducting systems.
The present invention provides a bell-and-spigot arrangement, whereby a spigot end of one duct section is inserted into a bell end of a next adjacent duct section, such that when the duct is inflated the spigot expands against the bell to form a substantially air-tight seal.
In the preferred embodiment of the invention, the sections of ducting are connected together by clips that are permanently attached to one section of ducting, so joining together or separating lengths of mine ducting takes significantly less time than in prior art flexible duct systems. The invention thus facilitates quicker duct installation and removal. The present invention also facilitates correct and effective connections, the correct number and position of the clips being pre-determined since the clips are pre-attached to the ducting. The operator need only snap adjoining sections of ducting together. Moreover, the present invention eliminates the need to purchase separate clips which are hard to install correctly and to remove.
Accordingly, the manpower costs involved in the installation, removal, repair, and maintenance of the duct system of the present invention are significantly reduced.
The duct system of the present invention is easy to assemble in a deflated condition, and then readily inflate when air is passed through the ducting.
The present invention also reduces energy costs by reducing air pressure loss arising from joint leakage. When a,ir is pumped into the initially deflated sections of ducting, the spigot (outlet) end of the duct section expands fully into the bell (inlet) end of the next adjacent duct section, creating a substantially air-tight seal. The upstream duct section remains preferably about 4 to 6 inches inside the end ring of the next adjacent downstream duct section, effectively providing a substantially leak proof joint system. Thus, leakage arising from incomplete duct section seals and installation errors associated with prior art duct systems are eliminated.
1 S The present invention also eliminates the bunching of duct tubing at the joints. Accordingly, joint restriction is eliminated and air resistance is minimized, resulting in fan energy savings. Thus, with the duct system of the present invention, shorter lengths of ducting (for example, 25 feet) can be used on long development runs without the air pressure loss normally associated with the resistance imparted by multiple joints and the joint leakage associated with each joint. One advantage to using shorter lengths of duct sections is the ability to keep the end of the duct closer to the face as the work crew advances.
Another advantage to utilizing shorter lengths of duct sections is that a shorter duct section damaged by equipment or blasting is cheaper to replace, so a large tear from blasting or equipment does not result in the loss occasioned by a longer, more expensive length of duct section.
The present invention is interchangeable with other duct systems presently being used in mines. No transitions or adapters are required. Mines can thus phase out the old mufti-clip system gradually, since the present invention can be connected to conventional duct sections with standard mufti-clips, while downstream where duct sections of the present invention are utilized the duct sections can be connected together according to the invention.
The present invention also provides a rapid attachment system for suspending the duct from a messenger cable or screen. Each duct section may be provided with at least one tuck or extension of wall material extending from an external surface of the duct wall, by which the duct is suspended by suspending clips.
The present invention thus provides a flexible ventilation ducting system comprising at least two flexible duct sections for connection in a bell-and-spigot configuration, each having an open spigot end and an open bell end in communication therewith, a plurality of first fastening members attached about an exterior of each duct section near the spigot end, and a plurality of second fastening members attached about an interior of each duct section near the bell end, wherein when the spigot end of one duct section is inserted into the bell end of another duct section and the first and second fastening means are engaged, air blown through the duct causes the spigot end to expand within the bell end to create a substantially air-tight seal between the duct sections.
Brief Description of the Drawings In drawings which illustrate by way of example only preferred embodiments of the invention, Figures 1 a, 1 b, and 1 c are schematic drawings views showing the progressive addition of duct sections to bring fresh air to work crews as the mine heading advances.
Figure 2 is an elevational exploded view showing the manner of engaging the bell end of one flexible duct section to the spigot end of the next adjacent flexible duct section.
Figures 3A and 3B are respectively elevational views of standard and heavy-duty SWS clips for attaching adjacent duct sections.
Figure 4 is an elevational view of the clip of Figure 3A attached to the outlet end of a duct section.
Figures SA and SB are respectively elevational views of standard and heavy-duty "D" Rings fox attaching adjacent duct sections.
Figures 6A to 6D are respectively elevational views of various embodiments of SWS clips which can be used with the system of the invention.
Figures 7A to 7C are respectively schematic views showing preferred locations of clips along the circumference of small round, large round and oval ducting.
Figure 8 is an elevational view of the extension of duct material extending from the external surface from a section of flexible duct tubing.
Figure 9 is a perspective view of ducting suspended on a messenger cable.
Figure 10 is a perspective view of round reinforced ducting with a suspending clip attached to a grommet tuck.
Figure 11 is a perspective view of oval ducting with suspending clips attached to multiple grommet tucks.
Figure 12 is a perspective view of spiral oval ducting with suspending clips attached to multiple grommet tucks.
Detailed Description of the Invention A preferred embodiment of the invention is shown in Figures l and 2. The ducting system according to the invention comprises flexible duct sections 12, which connect in the manner described in detail below. The duct 10, as used in a mine, is attached to one or more high-pressure fans to provide ventilation into the mine. The duct 10 may vary in diameter and length, and duct sections 12 are added as needed to progress deeper into the mine and maintain proximity with the working face of the heading 2. For example, Figures 1 a, 1 b, and 1 c illustrate how the addition of duct tubing brings fresh air to work crews as the heading 2 advances. Figure 1 c illustrates the duct 10 suspended from one or more messenger cables running along the top of a mining tunnel, as is conventional.
The flexible duct sections 12 can be provided in varying configurations, including round and oval. The duct sections 12 can also be provided in lay-flat type in which there is no reinforcement for the duct wall and thus the deflated duct section 12 can be laid flat when deflated; and a spiral reinforced type in which the duct section 12 is maintained in a substantially open condition by a reinforcing wire helically circumscribing the interior of the duct section 12. The duct section 12 may be composed of any suitable material, including polyvinyl chloride or woven polyolefin fabric flexible sheeting, as is well-known in the art.
As illustrated i.n Figure' l, the present invention comprises a plurality of duct sections 12, each having a spigot end 14 (which in order to reduce airflow resistance is advantageously the outlet end of the duct section 12) and a bell end 15 (which for the same reason is advantageously the inlet end of the duct section 12).
Thus, in the preferred embodiment air enters the duct section 12 at the bell end 32 and exits the duct section at the spigot end 14. For ease of reference for the operator, either or both ends of a duct section 12 may be marked, for example by a tag.
The circumference of the spigot end 14 is slightly smaller than the circumference of the bell end 32 so that the spigot end 14 may pass through the bell end 32 and enter the lumen of the adjacent duct section 12b.
In the present invention, each duct section 12 is provided with a plurality of first fasteners 16 that are attached about the exterior surface proximate to the spigot end 14 of the duct tubing member 12. In one embodiment the first fastening member 16 is a clip of the type shown in Figure 6, which illustrates various versions of clips 16 by way of example only. Within the interior of the same duct section 12, but proximate to the bell end 32, are attached a plurality of second fastening member 34.
In one embodiment the second fastening member 34 is a "D" ring, as shown in Figure 7, which illustrates different versions of the "D" ring by way of example only. At both the bell end 32 and spigot end 14 is an end ring 20 that provides structural support to the end of the duct section 12.
Figure 2 illustrates how, according to the present invention, adjacent duct sections 12a and 12b are secured to one another to create a substantially air-tight seal between the spigot end 14 of a first section 12a and the inlet end 32 of a second section 12b. The spigot end 14 of the first section 12a is inserted into the lumen of the second section 12b at the bell end 32 of the second section 12b, and each first fastening member 16 is attached to the corresponding second fastening member 34 at the bell end 32. The adjacent duct sections 12a and 12b are thus releasably attached to one another. When air is passed through the duct 10 under pressure, for example, by a high pressure fan 4, both of the duct sections 12a, 12b expand. As a result, the exterior surface of the spigot end 14 of the upstream duct section 12a is forced against the interior surface of the downstream duct section 12b, preferably with an overlap of about 4 to 6 inches. This method of attachment is repeated by connecting additional duct sections 12 as described above, as needed.
The first fastening members 16 are preferably permanently attached to the spigot end 14 of the duct section 12. One means of attaching the first fastening members 16 is illustrated by way of example in Figure 3, wherein a strap 18 such as 1 inch polyvinyl chloride webbing about 5 inches long, or any other suitable material, is attached, for example sewn, onto the exterior surface of the duct section 12.
This secures the fastening member 16 to the duct section 12.
Where the connection between the upstream duct section 12a and the downstream duct section 12b requires additional strength, the strap 18 may be reinforced by doubling, as shown for example in Figure 3B, and/or increasing the length of strap 18, to thus increase the surface area of the strap 18 which is available to be sewn onto the duct section 12. Additional strength may also be obtained by utilizing a stronger fastening member 16. In one embodiment, the fastening member 16 is made of steel, or another suitably strong material. Variations of the first fastening member 16, shown by way of example only, are illustrated in Figures 6A to 6D.
The second fastening member 34 is also preferably permanently attached to the duct section 12. In the oval duct configuration, this helps to align successive duct sections 12. One example of means for attaching the second fastening member 34 is illustrated in Figure SA. A strap 36, similar to the strap 18 for the first fastening member 16, or any other suitable material, is attached, for example sewn, onto the interior surface of the duct section 12 to secure the attachment means 34.
Again, where the connection between the first duct section 12a and the second duct section 12b requires additional strength, the strap member 36 may be reinforced by adding a second strap 34, as shown for example in Figure SB, and/or increasing the length of the strap member 36, to thus increase the surface area of the second strap member 36 which can be sewn on to the duct section 12. Additional strength may also be obtained by utilizing a stronger fastener 34. In one embodiment, the second fastener is a "D" ring made of steel or another suitable material, or the "D" ring may be larger.
A sufficient number of the first and second fastening members 16, 34 is required to hold the adjacent duct sections 12a and 12b together. This number will vary depending on such factors as the diameter, type and configuration of the duct sections 12. For example, for round lay-flat and spiral reinforced ducts, the following number of pairs of fastening members 16, 34 is recommended:
12 inch diameter to 29 inch diameter - 4 pairs 30 inch diameter to 41 inch diameter - 5 pairs 42 inch diameter to 53 inch diameter - 6 pairs 54 inch diameter to 60 inch diameter - 8 pairs 61 inch diameter and greater -10 or more pairs For oval lay-flat and for oval spiral reinforced duct tubing with diameters of 60 inches or less, it should be sufficient to utilize between 6 and 12 pairs of fastening members 16, 34. Examples are shown in Figures 7A to 7C. In general, the fastening members 16, 34 should be evenly spaced about the duct sections 12.
The present invention also provides a rapid attachment system for suspending the duct 10 from a messenger cable 58 or screen (not shown). As illustrated in Figure 8, each duct section 12 may be provided with at least one tuck 50 of wall material extending from the external surface of the duct section 12, commonly known as "grommet tuck." In oval duct tubing 42 inches and more in diameter, two grommet tucks 50 are preferably used to support the larger width of the ducting 10 and to keep it stable when suspended, as shown in Figure 11.
One or more eyelets 52 along the tuck 50 receives attachment clips 54, for example "S" clips, each of which in turn secures a suspending clip 56; for example similar to the first fastening members 16. The suspending clips 56 in turn clip to the messenger cable 58 and suspend the duct 10 from the cable 58 as shown in Figures 3, 4 and 5. In another embodiment (not shown), the eyelets 52 in the tuck 50 can receive the suspending clips 56 directly.
The rapid attachment system described herein may be used to suspend the various configurations of duct sections 12, including round lay-flat configurations, oval lay-flat configurations, round spiral reinforced co~gurations, and oval spiral reinforced configurations. Unlike traditional 'paper clips,' the suspending clips 56 surround and lock to the messenger cable 58. Accordingly, a duct 10 suspended by suspending clips 56 is less likely to become detached from the messenger cable due to blasts other dislodging forces that are encountered in a mining environment.
Preferred embodiments of the invention having been thus described by way of example, it will be apparent to those skilled in the art that certain modifications and adaptations may be made without departing from the scope of the invention, as set out in the appended claims.
Field of the Invention This invention relates to flexible ducting. In particular, this invention relates to flexible ventilation ducting such as that used in the mining industry, in which duct sections are joined together to provide fresh air into a mine and to remove gases from within the mine.
Background of the Invention For decades, underground mines around the world have been using flexible ducting in lay-flat and spiral reinforced configurations (typically having diameters from 6 inches to over 120 inches), which are attached to high-pressure fans to provide ventilation within the mine. As mine headings advance, sections of duct, typically consisting of lengths from 25 feet to over 50 feet, are added to maintain air delivery to the working face of the heading. This is necessary to provide fresh air to miners working at these locations and to remove noxious gases generated by blasting and mining equipment.
Prior art flexible duct systems include ducts in which adjacent sections of ducting are connected to one another by clips or other similar attachment devices that are not permanently attached to the ducting. The clips used on prior art duct systems often fall off at fan start up or during blasting, or may be knocked off by passing equipment. Often such fallen clips become lost in the muck pile. Accordingly, the clips used in prior art duct systems frequently have to be replaced.
The clips used on prior art duct systems can also tear and otherwise damage the duct material during installation and removal of the duct system.
The significant manpower costs incurred when installing and removing prior art ducting is thus exacerbated by costs associated with repairs and system maintenance.
Further, the joints between adjacent sections of prior art ducting are sealed by connectors, clamps or other sealing devices in an attempt to minimize joint leakage. Often vent clips such as "mufti-clips" or connecting couplers are used. These are separate clips which must be attached to both adjoining duct sections at the rime of installation, which is time consuming. Typical installation errors associated with such prior art duct systems include incorrectly installing the clips, installing clips at the wrong location about the end of a duct section, installing too few clips to adequately connect adjacent duet sections, or incorrectly putting the ducting end rings together. Such errors result in leakage between adjacent duct sections, and occasionally failure of the duct under the high pressure of the ventilation fari.
The use of mufti-clips also often results in bunching of the duct tubing at the joints. Such bunching increases air resistance within the tubing, thus placing more energy demands on the ventilation fan.
Also, with conventional duct ventilation systems, the ducting is suspended by suspending clips colloquially known as "paper clips," which are bent or coiled pieces of wire that attach to a messenger cable or screen that runs along the tunnel and suspends the assembled ducting. A problem with such clips is that during installation, the installer must lift the ducting up to the messenger cable or screen and then twist the ducting to clip it on to the messenger cable. This is very time consuming.
Moreover, when removing the ducting, the suspending clips are difficult to undo and often the operator may just rip down the ducting and therefore tear the duct wall, rendering it in need of repair or useless. Also, such suspending clips are not as sturdy as is desirable in a mining environment.
Summary of the Invention The present invention addresses the above-mentioned problems of the prior art flexible ducting systems.
The present invention provides a bell-and-spigot arrangement, whereby a spigot end of one duct section is inserted into a bell end of a next adjacent duct section, such that when the duct is inflated the spigot expands against the bell to form a substantially air-tight seal.
In the preferred embodiment of the invention, the sections of ducting are connected together by clips that are permanently attached to one section of ducting, so joining together or separating lengths of mine ducting takes significantly less time than in prior art flexible duct systems. The invention thus facilitates quicker duct installation and removal. The present invention also facilitates correct and effective connections, the correct number and position of the clips being pre-determined since the clips are pre-attached to the ducting. The operator need only snap adjoining sections of ducting together. Moreover, the present invention eliminates the need to purchase separate clips which are hard to install correctly and to remove.
Accordingly, the manpower costs involved in the installation, removal, repair, and maintenance of the duct system of the present invention are significantly reduced.
The duct system of the present invention is easy to assemble in a deflated condition, and then readily inflate when air is passed through the ducting.
The present invention also reduces energy costs by reducing air pressure loss arising from joint leakage. When a,ir is pumped into the initially deflated sections of ducting, the spigot (outlet) end of the duct section expands fully into the bell (inlet) end of the next adjacent duct section, creating a substantially air-tight seal. The upstream duct section remains preferably about 4 to 6 inches inside the end ring of the next adjacent downstream duct section, effectively providing a substantially leak proof joint system. Thus, leakage arising from incomplete duct section seals and installation errors associated with prior art duct systems are eliminated.
1 S The present invention also eliminates the bunching of duct tubing at the joints. Accordingly, joint restriction is eliminated and air resistance is minimized, resulting in fan energy savings. Thus, with the duct system of the present invention, shorter lengths of ducting (for example, 25 feet) can be used on long development runs without the air pressure loss normally associated with the resistance imparted by multiple joints and the joint leakage associated with each joint. One advantage to using shorter lengths of duct sections is the ability to keep the end of the duct closer to the face as the work crew advances.
Another advantage to utilizing shorter lengths of duct sections is that a shorter duct section damaged by equipment or blasting is cheaper to replace, so a large tear from blasting or equipment does not result in the loss occasioned by a longer, more expensive length of duct section.
The present invention is interchangeable with other duct systems presently being used in mines. No transitions or adapters are required. Mines can thus phase out the old mufti-clip system gradually, since the present invention can be connected to conventional duct sections with standard mufti-clips, while downstream where duct sections of the present invention are utilized the duct sections can be connected together according to the invention.
The present invention also provides a rapid attachment system for suspending the duct from a messenger cable or screen. Each duct section may be provided with at least one tuck or extension of wall material extending from an external surface of the duct wall, by which the duct is suspended by suspending clips.
The present invention thus provides a flexible ventilation ducting system comprising at least two flexible duct sections for connection in a bell-and-spigot configuration, each having an open spigot end and an open bell end in communication therewith, a plurality of first fastening members attached about an exterior of each duct section near the spigot end, and a plurality of second fastening members attached about an interior of each duct section near the bell end, wherein when the spigot end of one duct section is inserted into the bell end of another duct section and the first and second fastening means are engaged, air blown through the duct causes the spigot end to expand within the bell end to create a substantially air-tight seal between the duct sections.
Brief Description of the Drawings In drawings which illustrate by way of example only preferred embodiments of the invention, Figures 1 a, 1 b, and 1 c are schematic drawings views showing the progressive addition of duct sections to bring fresh air to work crews as the mine heading advances.
Figure 2 is an elevational exploded view showing the manner of engaging the bell end of one flexible duct section to the spigot end of the next adjacent flexible duct section.
Figures 3A and 3B are respectively elevational views of standard and heavy-duty SWS clips for attaching adjacent duct sections.
Figure 4 is an elevational view of the clip of Figure 3A attached to the outlet end of a duct section.
Figures SA and SB are respectively elevational views of standard and heavy-duty "D" Rings fox attaching adjacent duct sections.
Figures 6A to 6D are respectively elevational views of various embodiments of SWS clips which can be used with the system of the invention.
Figures 7A to 7C are respectively schematic views showing preferred locations of clips along the circumference of small round, large round and oval ducting.
Figure 8 is an elevational view of the extension of duct material extending from the external surface from a section of flexible duct tubing.
Figure 9 is a perspective view of ducting suspended on a messenger cable.
Figure 10 is a perspective view of round reinforced ducting with a suspending clip attached to a grommet tuck.
Figure 11 is a perspective view of oval ducting with suspending clips attached to multiple grommet tucks.
Figure 12 is a perspective view of spiral oval ducting with suspending clips attached to multiple grommet tucks.
Detailed Description of the Invention A preferred embodiment of the invention is shown in Figures l and 2. The ducting system according to the invention comprises flexible duct sections 12, which connect in the manner described in detail below. The duct 10, as used in a mine, is attached to one or more high-pressure fans to provide ventilation into the mine. The duct 10 may vary in diameter and length, and duct sections 12 are added as needed to progress deeper into the mine and maintain proximity with the working face of the heading 2. For example, Figures 1 a, 1 b, and 1 c illustrate how the addition of duct tubing brings fresh air to work crews as the heading 2 advances. Figure 1 c illustrates the duct 10 suspended from one or more messenger cables running along the top of a mining tunnel, as is conventional.
The flexible duct sections 12 can be provided in varying configurations, including round and oval. The duct sections 12 can also be provided in lay-flat type in which there is no reinforcement for the duct wall and thus the deflated duct section 12 can be laid flat when deflated; and a spiral reinforced type in which the duct section 12 is maintained in a substantially open condition by a reinforcing wire helically circumscribing the interior of the duct section 12. The duct section 12 may be composed of any suitable material, including polyvinyl chloride or woven polyolefin fabric flexible sheeting, as is well-known in the art.
As illustrated i.n Figure' l, the present invention comprises a plurality of duct sections 12, each having a spigot end 14 (which in order to reduce airflow resistance is advantageously the outlet end of the duct section 12) and a bell end 15 (which for the same reason is advantageously the inlet end of the duct section 12).
Thus, in the preferred embodiment air enters the duct section 12 at the bell end 32 and exits the duct section at the spigot end 14. For ease of reference for the operator, either or both ends of a duct section 12 may be marked, for example by a tag.
The circumference of the spigot end 14 is slightly smaller than the circumference of the bell end 32 so that the spigot end 14 may pass through the bell end 32 and enter the lumen of the adjacent duct section 12b.
In the present invention, each duct section 12 is provided with a plurality of first fasteners 16 that are attached about the exterior surface proximate to the spigot end 14 of the duct tubing member 12. In one embodiment the first fastening member 16 is a clip of the type shown in Figure 6, which illustrates various versions of clips 16 by way of example only. Within the interior of the same duct section 12, but proximate to the bell end 32, are attached a plurality of second fastening member 34.
In one embodiment the second fastening member 34 is a "D" ring, as shown in Figure 7, which illustrates different versions of the "D" ring by way of example only. At both the bell end 32 and spigot end 14 is an end ring 20 that provides structural support to the end of the duct section 12.
Figure 2 illustrates how, according to the present invention, adjacent duct sections 12a and 12b are secured to one another to create a substantially air-tight seal between the spigot end 14 of a first section 12a and the inlet end 32 of a second section 12b. The spigot end 14 of the first section 12a is inserted into the lumen of the second section 12b at the bell end 32 of the second section 12b, and each first fastening member 16 is attached to the corresponding second fastening member 34 at the bell end 32. The adjacent duct sections 12a and 12b are thus releasably attached to one another. When air is passed through the duct 10 under pressure, for example, by a high pressure fan 4, both of the duct sections 12a, 12b expand. As a result, the exterior surface of the spigot end 14 of the upstream duct section 12a is forced against the interior surface of the downstream duct section 12b, preferably with an overlap of about 4 to 6 inches. This method of attachment is repeated by connecting additional duct sections 12 as described above, as needed.
The first fastening members 16 are preferably permanently attached to the spigot end 14 of the duct section 12. One means of attaching the first fastening members 16 is illustrated by way of example in Figure 3, wherein a strap 18 such as 1 inch polyvinyl chloride webbing about 5 inches long, or any other suitable material, is attached, for example sewn, onto the exterior surface of the duct section 12.
This secures the fastening member 16 to the duct section 12.
Where the connection between the upstream duct section 12a and the downstream duct section 12b requires additional strength, the strap 18 may be reinforced by doubling, as shown for example in Figure 3B, and/or increasing the length of strap 18, to thus increase the surface area of the strap 18 which is available to be sewn onto the duct section 12. Additional strength may also be obtained by utilizing a stronger fastening member 16. In one embodiment, the fastening member 16 is made of steel, or another suitably strong material. Variations of the first fastening member 16, shown by way of example only, are illustrated in Figures 6A to 6D.
The second fastening member 34 is also preferably permanently attached to the duct section 12. In the oval duct configuration, this helps to align successive duct sections 12. One example of means for attaching the second fastening member 34 is illustrated in Figure SA. A strap 36, similar to the strap 18 for the first fastening member 16, or any other suitable material, is attached, for example sewn, onto the interior surface of the duct section 12 to secure the attachment means 34.
Again, where the connection between the first duct section 12a and the second duct section 12b requires additional strength, the strap member 36 may be reinforced by adding a second strap 34, as shown for example in Figure SB, and/or increasing the length of the strap member 36, to thus increase the surface area of the second strap member 36 which can be sewn on to the duct section 12. Additional strength may also be obtained by utilizing a stronger fastener 34. In one embodiment, the second fastener is a "D" ring made of steel or another suitable material, or the "D" ring may be larger.
A sufficient number of the first and second fastening members 16, 34 is required to hold the adjacent duct sections 12a and 12b together. This number will vary depending on such factors as the diameter, type and configuration of the duct sections 12. For example, for round lay-flat and spiral reinforced ducts, the following number of pairs of fastening members 16, 34 is recommended:
12 inch diameter to 29 inch diameter - 4 pairs 30 inch diameter to 41 inch diameter - 5 pairs 42 inch diameter to 53 inch diameter - 6 pairs 54 inch diameter to 60 inch diameter - 8 pairs 61 inch diameter and greater -10 or more pairs For oval lay-flat and for oval spiral reinforced duct tubing with diameters of 60 inches or less, it should be sufficient to utilize between 6 and 12 pairs of fastening members 16, 34. Examples are shown in Figures 7A to 7C. In general, the fastening members 16, 34 should be evenly spaced about the duct sections 12.
The present invention also provides a rapid attachment system for suspending the duct 10 from a messenger cable 58 or screen (not shown). As illustrated in Figure 8, each duct section 12 may be provided with at least one tuck 50 of wall material extending from the external surface of the duct section 12, commonly known as "grommet tuck." In oval duct tubing 42 inches and more in diameter, two grommet tucks 50 are preferably used to support the larger width of the ducting 10 and to keep it stable when suspended, as shown in Figure 11.
One or more eyelets 52 along the tuck 50 receives attachment clips 54, for example "S" clips, each of which in turn secures a suspending clip 56; for example similar to the first fastening members 16. The suspending clips 56 in turn clip to the messenger cable 58 and suspend the duct 10 from the cable 58 as shown in Figures 3, 4 and 5. In another embodiment (not shown), the eyelets 52 in the tuck 50 can receive the suspending clips 56 directly.
The rapid attachment system described herein may be used to suspend the various configurations of duct sections 12, including round lay-flat configurations, oval lay-flat configurations, round spiral reinforced co~gurations, and oval spiral reinforced configurations. Unlike traditional 'paper clips,' the suspending clips 56 surround and lock to the messenger cable 58. Accordingly, a duct 10 suspended by suspending clips 56 is less likely to become detached from the messenger cable due to blasts other dislodging forces that are encountered in a mining environment.
Preferred embodiments of the invention having been thus described by way of example, it will be apparent to those skilled in the art that certain modifications and adaptations may be made without departing from the scope of the invention, as set out in the appended claims.
Claims (9)
1. A flexible ventilation ducting system comprising at least two flexible duct sections for connection in a bell-and-spigot configuration, each having an open spigot end and an open bell end in communication therewith, a plurality of first fastening members attached about an exterior of each duct section near the spigot end, and a plurality of second fastening members attached about an interior of each duct section near the bell end, wherein when the spigot end of one duct section is inserted into the bell end of another duct section and the first and second fastening means are engaged, air blown through the duct causes the spigot end to expand within the bell end to create a substantially air-tight seal between the duct sections.
2. The system of claim 1 wherein each duct section has an end ring at each end.
3. The system of claim 2 wherein the fastening members are attached near the end rings.
4. The system of claim 3 wherein the end ring of the spigot end is passed through the end ring of the bell end to join adjacent duct sections together.
5. The system of claim 1 wherein the first fastening member is a releasable clip.
6. The system of claim 1 wherein the second fastening member is a ring.
7. The system of claim 3 wherein the end ring is wrapped into a wall of the duct section and retained by heat welding.
8. The system of claim 1 wherein each duct section has an extension of wall material extending from an external surface and one or more openings through said extension for affixing a third fastening member to the extension.
9. The system of claim 8 wherein the third fastening member attaches to a suspension cable.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA 2421334 CA2421334A1 (en) | 2003-03-07 | 2003-03-07 | Flexible duct system |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA 2421334 CA2421334A1 (en) | 2003-03-07 | 2003-03-07 | Flexible duct system |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2421334A1 true CA2421334A1 (en) | 2004-09-07 |
Family
ID=32932234
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA 2421334 Abandoned CA2421334A1 (en) | 2003-03-07 | 2003-03-07 | Flexible duct system |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA2421334A1 (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2008060770A1 (en) * | 2006-11-15 | 2008-05-22 | Rite-Hite Holding Corporation | External rib cage for an inflatable air duct |
| EP3067517A1 (en) | 2015-03-13 | 2016-09-14 | Sema | Flexible aeration duct suitable for being switched and duct-separation device |
-
2003
- 2003-03-07 CA CA 2421334 patent/CA2421334A1/en not_active Abandoned
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2008060770A1 (en) * | 2006-11-15 | 2008-05-22 | Rite-Hite Holding Corporation | External rib cage for an inflatable air duct |
| US9518756B2 (en) | 2006-11-15 | 2016-12-13 | Rite-Hite Holding Corporation | External rib cage for an inflatable air duct |
| EP3067517A1 (en) | 2015-03-13 | 2016-09-14 | Sema | Flexible aeration duct suitable for being switched and duct-separation device |
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