WO2010120183A1 - System for preventing contamination of manholes and pipes - Google Patents

Abstract

Collector (100) for debris in manholes, the collector (100) comprising a bag (110) wherein different straps (125, 140) and locking clips (126, 130) attaches the bag (110) to different manholes. The same bag (110) can be suspended by straps (140) attached in a concrete manhole, or pulled over a corrugated plastic riser and be clamped using a (longer) strap of the same type. The collector (100) can easily be removed, and re-attached. Flexible bags and straps make it easy to transport and dispose the system in a construction site.

Description

System for preventing contamination of manholes and pipes

BACKGROUND Technical field This invention regards a system for preventing contamination of manholes and pipes in general, and in water and sewer systems in particular.

Prior and related art

Vertical manholes are used in water and sewer systems for different purposes. A completed manhole usually consist of a vertical riser made of concrete or plastic which is closed at its upper end with a cast-iron frame and lid or grating.

A typical manhole, e.g. a drainage tank in a drainage line, is made of prefabricated concrete riser sections placed on top of each other. In the construction period, the manhole can be completed by a concrete top lid or conical riser before filling is packed around it. The top lid or conical riser has an opening with lesser diameter (0 about 650 mm). The manhole can be left in this state for several weeks or months before it is completed with one or more adjustment rings, cast-iron frame and a manhole lid or grating. Adjustment rings are put on top later in order to adapt the distance to final terrain, e.g. such that the lid is aligned with the tarmac on a finished street or road. In this period, filling material is supplied around. In the periods when filling material is supplied around the manhole, rocks, gravel, tarmac and the like is likely to fall into the manhole.

A metal supporting ring can be placed between the concrete elements to prevent the concrete riser element(s) from being displaced. This supporting ring is shaped as a band having an outer diameter slightly less than the inner diameter of the concrete riser elements, and a flange extending radially outwards. This flange is disposed between the concrete elements when the supporting ring is in use.

In numerous constructions, manholes made of corrugated or grooved risers of plastic in addition to or in lieu of concrete manholes. The riser forms the top of the plastic manhole. Standard diameters for plastic risers are 0 315, 400, 425 and 630 mm. The risers are delivered with a thin, temporary plastic lid which is easily pivoted, and which is ill suited to prevent debris from falling into the manhole in the construction period. It is possible to purchase more solid lids for the risers, but these lids are relatively expensive to acquire.

In some manholes, valves for a water pipe or other equipment can be present. This equipment is often coated with enamel or paint. Rocks and other filling material falling down onto the equipment may damage the equipment such that it will no longer function, or harm the surface coating. Even if the surface coating is repaired afterwards, such a repaired unit will be more prone to corrosion than an unharmed unit.

Debris in the bottom of a manhole can also prevent inspection of the pipeline, e.g. by preventing a run-in tool having a camera or other sensors from advancing.

A number of devices are known to prevent debris from entering a manhole. Various lids and gratings are known from, for example, US 2002/023,864 A1 , US 6,254,770 B1 , US 5,733,444 A, US 3,621 ,623 A og US 2,615,526 A. These are essentially adapted to frames in an existing manhole. Because they are made of metallic elements having relatively large openings, they are ill suited to catch sand and other fine grained debris, and they are also ill suited for use in plastic manholes.

Metallic baskets for catching debris are known from, /hter alia, US 7,132,045 B1 and US 2,615,526 A, and security net to prevent damage from falling items in general are known from , inter alia, DE 2835724 A1 , DE 10252018 A1 , JP 9060018 A and CN 2782770Y. These baskets and nets also have relatively large openings, and hence easily let through sand and other fine grained debris.

In order to prevent fine grained material from entering the manhole, fabric is used rather than gratings, metallic baskets or nets. One example of such a bag is disclosed in US 6,517,709 B1. The apparatus of US 6,517,709 B1 is, however, ill suited for use in manholes made from plastic risers, and requires adaptations in order to be used during construction works, e.g. before the manhole is completed by a frame and lacks horizontal shoulders on which to rest a metal ring.

US patent no 6.955,498 B1 discloses an apparatus for preventing filling material and the like from entering a pipe in a construction period. The apparatus substantially comprises a steel ring with a radial through cut, a flexible fabric attached to the ring, and a clamp fixed to the ends on each side of the cut. The clamp is used to force the ends of the steel ring away from each other, so that the steel ring is forced against a pipe wall. Then, the fabric prevents debris from entering the pipe. The apparatus may be attached horizontally, e.g. over the opening at the top of the manhole, or vertically at the entrance to a horizontal pipe. The impact from a falling rock can easily overcome the friction force due to a horizontal ring being pressed against the pipe wall. According to US patent no 6,955,498 B1 , the ring therefore should be placed on top of a horizontal shoulder (e.g. the frame for a manhole lid) when attached to cove a manhole. Hence, the apparatus is impractical in vertical pipes without horizontal shoulders. It is also impractical in conical risers, but it can be adapted to corrugated plastic pipes by reducing the clamping force so that the plastic pipe cracks when the apparatus is attached. A third disadvantage of the apparatus, is that it requires relatively expensive materials such as steel rings and a comparatively complicated clamp.

US 5,549,342 A discloses a debris catching net which can be lifted out of a manhole by means of straps.

A first objective of the present invention is to provide a system for preventing debris from falling into the manhole during construction works. The systems must be capable of preventing rocks and other relatively heavy objects without it necessarily requires horizontal shoulders in the manhole. It must also prevent contamination from fine grained material, and at the same time let through water. The system also must be adaptable to both concrete and plastic manholes.

In the construction period, there is occasionally a need for access to the manhole, e.g. for mounting, inspection or other work. Hence, another objective of the present invention is to provide an apparatus that can easily be removed and disposed again in the manhole.

SUMMARY OF THE INVENTION The present invention solves these problems by providing a collector for debris in the manhole, the collector comprising a bag permeable to water, distinguished in that different straps and locking devices attach the bag to different manholes.

When the same bag can be suspended from straps stuck between concrete riser elements or pulled over a corrugated plastic riser and attached with a (longer) strap of the same type, a practical system which can be used on all manholes in a construction is achieved. The system also makes it simpler to manufacture larger series of bags and straps. This reduces manufacturing costs, and hence also solves problems of relatively high prices of known systems. It should be noted that this has technical consequences: If the price is too high, it will be less expensive to accept that debris falls into the manholes, and rather take the cost of tidying and repairs. This will in turn possibly lead to increased corrosion on components having damaged and repaired surface treatment, and thereby cause increased technical problems in the long run.

When the bag is attached by means of straps and latching clips, the bag can easily be removed when temporary access to the manhole is required in the construction period. Similarly, it is easy to re-attach the bag by means of straps and latching clips when the work is done.

Flexible bags and straps also makes the system easier to transport and distribute in a construction site than devices having heavier metal parts, such as e.g. steel rings.

Other advantageous embodiments are apparent from the accompanying claims. BRIEF DESCRIPTION OF THE DRAWINGS

The invention will now be described in greater detail with reference to the accompanying drawings, wherein similar reference numerals refer to similar elements, and where:

Fig. 1 shows a first embodiment adapted to concrete manholes.

Fig. 2 shows an attachment strap for attaching the net in fig. 1.

Fig. 3 shows a second embodiment adapted to plastic manholes. Fig. 4 shows a typical manhole for waterworks with a collector according to the invention.

Fig. 5 shows a typical storm drainage manhole with a collector according to the invention.

Fig. 6 shows suspension from a supporting ring in greater detail. Fig. 7 shows an alternative suspension for use in a concrete manhole without supporting rings.

Fig. 8 shows lifting using a chain tool.

Fig. 9 shows a reinforced collector viewed from above.

DETAILED DESCRIPTION

Fig. 1 shows a first embodiment of the invention comprising a collector 100, which can be attached to attachment hooks 150 by means of attachment straps and latching clips 130.

The collector on Fig. 1 is designed for use in manholes made of concrete or the like. It is suspended near the top of a manhole, and has a slightly smaller diameter than the opening at the upper end of the manhole, e.g. 0 630 mm.

The collector 100 consists of a bag 110 extended by an extension ring 120 and is suspended by means of attachment means, such as the shown latching clips 130, straps 140 and hooks 150. The collector and attachment means are dimensioned to withstand the load of a typical rock falling down from the height of an excavator. An over-dimensioned apparatus becomes unnecessary expensive, while under dimensioned nets or attachment means may lead to debris falling into the manhole.

The bag 110 should retain debris, but not water. As noted above, it is desirable that sand and other smaller particles are retained, so that fabric will be better suited than nets with larger mask sizes. At the same time, the bag 110 should let water through easily, so that suspension and locks do not have to be dimensioned for the weight of water that would otherwise collect in the bag 110. Experiments indicate that inexpensive fabric of natural fibres tends to degrade and weaken during a typical construction period, and thus lacks the required rupture strength and/or durability. Woven or non-woven polyester fabrics of kinds otherwise used for armament, filtering and separating solids in construction works, so-called geo- fabric, have turned out to be suitable. Woven fabric usually has a better tensile strength than non-woven fabric, but many non-woven fabrics have sufficient tensile strength to be used in the invention. Further, some woven polyester fabrics are easily split-up at the edges. Such fabrics are ill suited for sewing, but can be suitable for welding of seams. Selecting a specific fabric essentially depends on what is available in the market.

The shape of the bag 110 is less important. The bag 110 is hence shown generally elliptic in figure 8, and more conical in figures 4 and 5.

The extension ring 120 keeps the bag open at its upper end, and can, for example, be made of a flexible plastic pipe, e.g. having diameter 0 20 mm, inserted into a circumferential channel 121 near the upper edge of bag 110, or alternatively be welded to the bag 110. The extension ring can, as an alternative to the mentioned 0 20 mm pipe having a circular cross section, be a ring or a band having a rectangular cross section. Other alternatives will be known to one skilled in the art.

The collector 100 is suspended in attachment straps 140 and locking mechanisms (see Fig. 2), such that it is easily removable when one needs access to the manhole. The number of attachment straps 140 will normally be 3 or more to avoid that the collector pivots around an axis created by two attachment points only. The number of attachment straps 140 is determined by choice of materials and price, as more inexpensive straps with lower tensile strength are required to hold a given mass in the collector 100. Thus, the invention is not limited to 4 attachment straps as shown in figure 1.

In figure 1 , the locking device is shown as four locking clips 130 fit for flat, woven straps 140 of synthetic fibres. One skilled in the art will imagine a number of other embodiments made from straps, rope, chains and the like with accompanying locking devices such as hooks, splints etc. making it correspondingly simple to release the collector 100 so that it can be lifted out of the manhole. It should also be understood that the locking clips 130, which in figure 1 is shown attached to the collector, alternatively could have been attached to the attachment strap 140 shown in figure 2. In this alternative, straps 140 without locking clips 130 would be attached to the collector 100.

The straps 140 with attachment hooks 150 (see fig. 2) can remain in the manhole for the entire period of construction.

Lifting loops 160 are used when the collector is to be lifted out of the manhole. Such large loops as shown in figure 1 are advantageous when the collector 100 is to be lifted out of the manhole manually, and/or when large masses are not expected in the net. In large diameter manholes or where larger collections of debris are expected, such large loops can easily be buried under the debris. In addition, the weight of collected debris may make it impossible or unjustifiable to lift the collector 100 manually. In such cases, small lifting loops, e.g. in the shape of smaller loops of the same material as the attachment straps 140, are better suited. Small loops will not be buried by collected debris, but are more difficult to use when lifting manually. Hence, it may be necessary to use a lifting tool, e.g. with a common chain tool as shown in fig. 8, when the collector 100 is to be lifted out of the manhole. Further, small lifting loops may be manufactured from metal or plastic and connected to hooks or plate metal as shown in Fig. 6. Large and small lifting straps/lifting loops and rings are collectively denoted 'lifting loops' in the claims. Figure 2 shows attachment means for the collector 100 in figure 1. An attachment hook 150 is disposed at a first end of a strap 140. Such an attachment hook 150 is suited for attachment to supporting rings, as shown in greater detail in figure 6. The attachment means can alternatively be a thickened first end 141 of the strap 140 preventing the strap 140 from slipping back between the riser elements in the embodiment shown in figure 7.

In figure 2, the second end of the attachment strap 140 is a bevel cut edge which easily can be inserted in latching clips 130 attached to the collector 100. As noted, the latching clips 130 can alternatively be mounted at the second end of the attachment strap 140, and the collector 100 provided with attachment straps without latches. In both cases, the attachment strap 140 can be inserted into the latching clip 130 and tightened to desired height.

Figure 3 shows a second embodiment, where a net bag 110 is pulled over the top of a grooved or corrugated riser 200 made of a plastic material. A channel 121 , corresponding to the channel with an extension ring in figure 1 , in figure 3 contains a strap 125 with a latching clip 126. The channel 121 can, if desirable, be replaced by hoops, or the attachment strap 125 can be connected to the bag 110 by welding or in other suitable ways. The attachment strap 125 can be made of the same materials and provided with latching devices 126 as the attachment strap 140 discussed in connection with figures 1 and 2 above. The attachment strap 125 is preferably bevel cut at one of its ends so as to be easily inserted into the latching clip 126.

In use, the bag 110 is pulled over the outer side of the corrugated riser 200, the strap 125 is inserted into the latching clip 126 and is pulled tight, preferably such that the strap 125 and channel 121 lies within a groove on the pipe 200. The net bag 110 then falls into the pipe 200 for preventing debris from falling into the pipe while letting water through. For the reasons discussed in connection with figure 1 above, the net bag in figure 3 is also advantageously manufactured of geo-fabric, e.g. non-woven polyester as disclosed previously. Thus, the bag 110 on figure 3 corresponds to the bag 110 on figure 1. A standardized bag 110 with diameter 0 630 mm and channel 121 can therefore be used for the embodiment shown in Fig. 1 , as well as the embodiment shown in Fig. 3,. In the embodiment shown in Fig. 1 , an extension ring is inserted into the channel 121 , and in the embodiment shown in Fig. 3, an attachment strap is inserted into the channel 121. This increases the production volumes and reduces the cost of manufacture.

The bag 110 can be provided with a loop in the bottom (not shown), so that it easily can be lifted to the position shown in figure 3. This makes it easy to empty it for collected debris.

The following examples show further advantages and embodiments of the invention.

Example 1

Figure 4 shows a typical manhole 201 for waterworks with a valve 202 near the bottom. Permanent top lids 203 with opening 0 630 mm are often put in place early in the construction period, but is, for obvious reasons, not completed with adjustment rings and permanent frame and lid of cast-iron before the construction works are near completed. In some cases, it can still be desirable or necessary to protect equipment or prevent contamination of the manhole even before the top lid 203 is put in place. In such cases, a collector according to the invention (not shown) with diameter corresponding to the manhole (> 0 650mm) be used. Thus, it may be desirable to make collectors with diameters larger or smaller than about 650 mm.

The top lid 203 has an opening (0 about 650 mm) which may remain open for a large portion of the construction period before the permanent cast-iron lid is put in place, and where it therefore may be desirable to provide a collector 100 as shown. The distance from the top-lid 203 and final terrain 300 is usually adjusted with one or more adjustment rings 204 and floating support of the frame 211 (see fig 5) for manhole-lid 210, which frequently is made of cast iron. The adjustment rings 204 can be disposed at different points in time during the construction period, and can be used for attachment of a collector 100 according to the invention.

In some cases, it is required to use metal supporting rings 250 between concrete riser elements (201 , 203, 204) in order to prevent relative displacement between the concrete riser elements, e.g. when rocks and gravel is filled around the manhole and/or packed. In such cases, attachment means with an attachment hook 150 adapted to the supporting ring of the type shown in figures 2 and 6 be suitable. In other cases, adjustment rings 204 without supporting rings 250 may be used. In these cases, attachment means that are pinched between to concrete elements (see fig. 7) be suitable. Attachment means as shown in figure 7 can be cut when construction is finished. Other attachment means than those shown in figures 2, 3, 6 and 7 are also thinkable.

Example 2

Fig. 5 shows a typical drainage tank. The opening is here at the upper end of a skew-conical riser element 205. An adjustment ring 204 and floatingly supported cast-iron frame 211 adjust the distance to final terrain 300 aligned with the upper surface of the cast-iron lid 210. The collector 100 can be attached to supporting rings as described above, or by attachment means as shown in figure 7 that are pinched between two riser elements rather than against the top lid 203 as in example 1.

Thus, the present invention can be adapted to a large number of constructions by combining a relatively small number of components. One bag 110 can be used for waterline manholes with or without top-lids as shown in figures 4 and 5, as well as for plastic manholes with different diameters as disclosed in connection with figure 3. It is substantially the attachment means that are different in the different embodiments. One collector 100 can be used with different attachment means as shown in figures 2, 6 and 7, and described above depending on if use of supporting rings is specified or not in concrete manholes, and depending on whether corrugated risers 200 are used in the construction. Figure 6 shows a suspension with hooks 150 in greater detail. There is often a space between the inner diameter of the riser element and the outer diameter of the supporting ring, but it is not certain that this space is evenly distributed along the entire circumference. If there is insufficient space between riser element and supporting ring, the attachment hooks 150 can, to some extent, be displaced along the circumference of the supporting ring 250.

Figure 6 shows another embodiment of the attachment hook 150 than the one shown in figure 2. The embodiment shown in Fig. 6 has a lifting ring 155 giving a connection point for the hooks at the ends of a chain tool when the collector is to be lifted out of the manhole. The lifting ring 155 is provided near the top of the attachment hook 150 to prevent wedging when the collector 100 (not shown) is to be lifted out of the manhole.

Fig. 7 shows an alternative suspension, where a band or attachment strap 140 is provided radially between two concrete riser elements. The band 140 can be provided with a thicker distal end, and can be cut when the collector 100 is to be removed from the manhole. This embodiment is suitable for manholes without a metal supporting ring. A variety of the attachment straps 140 can be provided with loops (not shown) for connection with chain hooks (not shown) when the collector is to be lifted out of the manhole.

Figure 8 illustrates use of a common 4-part chain toll 400 for lifting a collector 100 out of a manhole. For this purpose, the collector may be provided with small lifting loops or lifting rings 155 as described above, where hooks in the ends of the chains (not shown) can be attached. This requires a lifting tool, whereas the embodiment with large lifting loops would be more practical if the collector should be lifted out manually. The lifting straps 160 shown in figure 1 can also be hooked on a lifting hook, and thus replace the chain tool 400 shown in figure 8.

Figure 9 shows a collector with reinforced parts, e.g. in the shape of bands 111 in the bag 110. The purpose of such a reinforcement is to increase the tensile strength of the bag, without having to to make the entire bag of a more expensive material with greater tensile strength. Such reinforcement can thus be provided by a net (not shown) of e.g. terylene or nylon on the outside of the bag. By combining materials in this manner, a standardized bag 110 can hence be used in constructions with stricter requirements for dimensioning for falling objects without risk for rupture of the bag 110, and without increasing the manufacturing costs due to a relatively small number of bags 110 having to be provided in a relatively expensive (possibly fibre reinforced) material.

Finally we note that small lifting loops 155 advantageously can be made of a synthetic material, that they advantageously are welded or sewn on the straps attached to the net bag, and that the large lifting loops 160 which are shown in figure 1 , and are suitable for manual lifting, for example can be inserted in or attached to the small loops 155, In such an embodiment, the large lifting loops 160 works lthe same way as the chain tool shown in figure 8. However, lifting loops/straps 160 of e.g. woven or braided synthetic material are lighter and simpler to transport than a chain tool. Large lifting loops 160 of another material than chains can also replace the chain tool on figure 8 in that the large lifting loops or straps 160 are hung directly on the crane hook during a lift as shown on figure 8. This further standardizes the net bag 110 and/or the collector 100 in that the net bag is similar in various applications, and that lifting means in the shape of optional lifting straps are provided.

The invention is defined in detail in the accompanying claims.

Claims

1. Collector (100) for debris in a manhole (200, 201 ), the collector (100) comprising a bag (110) permeable to water, characterized in that the bag (110) is provided with at least one strap (125, 140) adapted for attachment of the bag (110) in the manhole, and wherein the strap /125, 140) is releasable attached in a locking device (126, 130).

2. Collector according to claim 1 , characterized in that the locking device (130) is fixed to the bag (110).

3. Collector according to claim 2, characterized in that the strap (140) is releasable attached in the lockin device (130) at its first end, and has attachment means (141 , 150) adapted to the manhole at its second end.

4. Collector according to claim 3, characterized in that the attachment means is an attachment hook (150).

5. Collector according to claim 3, characterized in that the attachment means is a thickened end (141 ) of the strap (140).

6. Collector according to claim 1 , characterized in that the bag has a channel (121 ) along the circumference of the opening of the bag.

7. Collector according to claim 1 , characterized in that the bag has a supporting ring (120) along the circumference of the opening of the bag.

8. Collector according to claim 1 , characterized in that the bag has a strap (125) along the circumference of the opening of the bag.

9. Collector according to claim 1 , characterized in that the bag (110) is fixedly connected to lifting loops (155, 160).

10. Collector according to claim 1 , characterized in that the bag (110) is reinforced with tension distributing means (111 ).