CABLE GUIDE WITH MEANS FOR MONITORING SEWERS

. The present invention relates to the monitoring of sewers, and in particular to the monitoring of sewers in which network cables are laid along the flow channel at the bottom of a sewer.

In order to install a new hardwired network and minimise disruption caused by the laying of new cables, some network installers have taken to laying cables within sewer pipes rather than constructing dedicated conduits.

When laying cables within a sewer, the cheapest and simplest solution is to lay the cables along the flow channel at the bottom of the sewer. A cable lying parallel to the direction of flow in the flow channel has a minor to negligible effect on the flow rate and a similarly minor likelihood of snagging debris and thus blocking of the flow channel. At some point however, the cable must enter/exit the flow channel. At such points, the cable lies across the direction of flow and thus creates a significant barrier to flow and a greatly increased chance of causing a blockage. Accordingly, our prior application WO2008/009964 discloses the use of a dedicated cable guide to enable a network cable to enter/exit the flow channel with minimal impedance to the flow.

Another desirable factor for sewer operators is to be able to monitor the sewer. This can enable flow anomalies to be detected and may thus provide early warning of a blockage. This may be a particular worry for operators in cases where any potential impediment is laid in the flow channel of a sewer.

It is therefore an object of the present invention to make provision for the monitoring of conditions in a sewer in which a cable is laid.

According to a first aspect of the present invention there is provided a cable guide, suitable for enabling a cable lying in the flow channel of a sewer to traverse and exit the flow channel without substantially impeding the flow, the cable guide characterised in that the cable guide comprises one or more sensing elements and means for storing and/or communicating data relating to the output of the one or more sensing elements.

Such a cable guide allows a network cable to be laid in a sewer and for conditions within a sewer to be monitored whilst minimising the disruption to flow caused by a cable entering or exiting the flow channel.

The sensing element or elements may be operable to sense any suitable parameters including but not limited to: flow content such as the presence and/or concentration of effluent generally or specific effluent substances; flow rate; flow level or similar. Preferably, the device comprises a first sensing element operable to detect one or more particular substances within the flow and a second sensing element operable to detect the upper level of the flow. The first sensing element may comprise a suitable chemical sensing element operable to output an electrical signal when a target substance is sensed. The second sensing element may comprise a sensor operable to output an electrical signal indicative of the flow depth within the sewer. This may be achieved by a calorimetric sensor operable to output an electrical signal indicative of the upper limit of the flow within the sewer. Such a calorimetric

sensor may comprise an upstanding sensing element. Alternatively, this may be achieved by a temperature sensing element operable to output an electrical signal indicative of the variation in temperature of the flow and hence enable an estimate of flow depth to be made. In such a case, a cooler temperature may be taken to indicate a greater flow depth. As a further alternative, this may be achieved by a pressure sensing element operable to output an electrical signal indicative of the variation in pressure at the bottom of the flow channel and hence enable an estimate of flow depth to be made.

The cable guide preferably comprises both a data storage means and a data communication means. A control element may be provided operable to act as a link between the sensing element or elements and the communicator means and data storage means. A power source may also be provided. The power source may be rechargeable. LQ such embodiments, suitable energy scavenging means may be provided for recharging the power source.

The data storage means may be of any suitable form including but not limited to electronic magnetic or optical. In particular, the data storage means may comprise a non- volatile memory chip. The data storage means preferably stores data indicative of the output of the one or more sensing elements. Additionally or alternatively, the data storage means may store data relating to the particular time at which particular output signals were recorded and/or maximum or minimum signals output by a particular sensing element.

- A - The communication means may comprise a unit configured to transmit and/or receive signals via a particular wired or wireless communication link. The signals are preferably indicative of the output of the one or more sensing elements. The signals may additionally or alternatively be indicative of the identity and/or location of the cable guide and/or may be indicative of the local time/date.

The communication link may be a wired or wireless communication link. In the event that the link is wired it may be conveniently laid along side the network cable and/or comprise part of the network cable. In the event that the link is wireless, it may be utilise signals of any suitable frequency including RP and IR frequencies. If the link utilises RF signals, the link may be compatible with any suitable wireless network standard including but not limited to: GSM, 3 G, WiFi, WiMax or similar.

The cable guide may be a cable guide of the type described in our co-pending application WO2008/009964. Such a cable guide comprises: a body section adapted to lie substantially flush with the wall of the flow channel; and an arm section projecting from the body section, the arm section having a distal end positioned outside the flow channel when the body section lies flush with the flow channel wherein the arm section provides a passage suitable for carrying a cable, the passage extending between an opening provided in the body section and an opening provided at the distal end of the arm section. The passage in such a cable guide thus provides a means by which a cable can traverse the flow channel with minimal disturbance to the flow.

The cable guide may be formed from Polyvinyl Chloride, Polypropylene,

Glass Reinforced Plastic, stainless steel or any other material suitable for resisting decomposition by chemical or biological agents likely to be present within the sewer effluents such as oils, acids and other substances.

The body section may be adapted to lie substantially flush with: one wall of the flow channel; one wall of the flow channel and at least part of the base of the flow channel; or both walls of the flow channel and the base of the flow channel. In order that the body section may lie substantially flush with the wall of the flow channel, one face of the body section may be shaped to correspond with the wall of the flow channel. In some embodiments, the body may be shaped so as to lie within a recess provided in the wall of the flow channel.

A second face of the body section forms a boundary to the flow channel. The second face may be shaped and/or otherwise adapted to minimise disturbance of the flow. The opening provided on the body section may be provided on the second face.

The cable may run across the second face of the body to the opening. In such embodiments, in order to ensure that the cable enters the opening at an angle that will minimise impedance of the flow, one or more cable clips may be provided. The or each clip may be provided on the second face of the body section. In such embodiments, the clips may be formed integrally with the body portion. Additionally or alternatively, one or more cable clips may be provided directly on the walls or base of the flow channel. Preferably, one cable clip is provided adjacent to the opening provided in the second face of the body section, hi one preferred embodiment, the or

each clip comprises a pair of resilient jaws adapted to retain a cable pushed into a position between the jaws. Additionally, to further secure the retention of the cable, a locking element may be provided, the locking element adapted, in use, to wrap over the cable and enclose the cable within the clip. Preferably, the clip (and in such embodiments the locking element) will be formed from stainless steel.

Alternatively, the opening may be provided at or towards the periphery of the second face and the cable may run behind the second face. In such embodiments, the cable may ran in an extension of the passageway between the first and second faces. In an alternative to this arrangement, the cable may run across the first face of the body to enter the passageway. In order to maintain the substantially flush relationship between the body section and the wall of the flow channel, either or both may be provided with a recessed channel along which the cable may run.

The arm section may be provided in a fixed relationship to the body portion. Alternatively, the arm section may be adapted such that its orientation relative to the body portion may be varied and/or such that it may be bent into an advantageous shape or position. Similarly, the body section may be adapted to be bent into an advantageous shape. This will allow the cable guide to be adapted to local variations in the size and/or shape of the flow channel.

The arm section may be adapted to minimise disturbance to any flow outside the flow channel. Such additional flows may occur during peak usage or due to dissipation of heavy rainfall. To achieve this, the arm section may have a lower face

adapted to lie flush with the sewer. Additionally, the arm section may have an upper face shaped and/or otherwise adapted to minimise disturbance of the flow.

The arm section and/or the body portion may be retained in position by use of a suitable adhesive, such as an epoxy resin or similar. Preferably, the adhesive is adapted to cure within a time period of say, 1 hour or less. Most preferably, the adhesive is adapted to cure within a time period of say, 15 minutes or less.

Advantageously, the adhesive is adapted to cure in the presence of water.

Alternatively, the body section may be secured in position by means of suitable fixing means. The suitable fixing means may comprise bolts, screws, nails or similar driven into the wall of the flow channel through fixing holes provided in the body.

In some embodiments, the arm section may be adapted to lie in a pre-existing or specifically prepared groove or recess in the sewer. In such embodiments, the arm section may be retained in the groove or recess by adhesive or any other suitable means. Preferably, in such embodiments, the arm section and/or body portion substantially fills the groove or recess, such that a smooth flow may be achieved. If the arm section and/or body portion does not fill the groove or recess, then a suitable filler material may be used to fill and/or smooth over the groove or recess.

In one preferred embodiment, the body section comprises a panel shaped to conform to the profile of the flow channel and the arm section comprises a tube projecting from the face of the body section adapted to conform to the profile of the flow channel.

According to a second aspect of the present invention there is provided a network comprising: one or more cables laid along the flow channels of sewers; and one or more cable guides according to the first aspect of the present invention.

The network of the second aspect of the present invention may incorporate any or all of the features described in relation to the cable guide of the first aspect of the invention as desired or as appropriate.

Preferably, a cable guide according to the first aspect of the present invention is provided at each point where a cable is required to enter/exit the flow channel of a sewer. The cable guides may be provided on either side of bends and/or junctions in the sewer and at places wherein the cable is to exit the sewer altogether. At such points the cable may be pinned to the walls or roof of the sewer once it exits the flow channel. Additionally or alternatively, the cable may be passed into a bypass tube or duct or into an exit duct once it exits the flow channel. Where the cable exits the sewer, the exit point of the cable from the sewer may be sealed around the cable to inhibit the escape of noxious or unpleasant gases.

The network can be used for any data. The cables within the network may be adapted to carry electrical or optical data signals and may thus be electrical data cables or fibre optic cables as required.

According to a third aspect of the present invention there is provided a method of laying a cable network incorporating at least one cable lying in the flow channel of a sewer comprising the steps of: laying a cable in the flow channel of a sewer; installing a cable guide according to the first aspect of the present invention at points

wherein the cable is required to enter/exit the flow channel; and passing the cable through the cable guide.

The method of the third aspect of the present invention may incorporate any or all of the features described in relation to the cable guide of the first aspect of the invention or the network of the second aspect of the present invention as desired or as appropriate.

In embodiments wherein a clip is provided, the method may include the additional step of fixing the cable in position using the clip.

The method may involve providing for the cable to leave the flow channel on either side of bends and/or junctions in the sewer and at places wherein the cable is to exit the sewer altogether. At such points the method may involve pinning the cable to the walls or roof of the sewer once it exits the flow channel. Additionally or alternatively, the method may involve passing the cable into a bypass tube or duct or into an exit duct once it exits the flow channel. Where the cable exits the sewer, the method may involve sealing the exit point of the cable from the sewer around the cable to inhibit the escape of noxious or unpleasant gases.

According to fourth aspect of the present invention there is provided a method of installing a cable guide in accordance with the first aspect of the present invention in the flow channel of a sewer comprising the steps of: applying adhesive to the cable guide; and positioning the cable guide at a desired location in the flow channel of a sewer.

The method of the fourth aspect of the present invention may incorporate any or all of the features described in relation to the cable guide of the first aspect of the invention, the network of the second aspect of the present invention or the method of the third aspect of the present invention as desired or as appropriate.

In relation to some embodiments, the method may incorporate the step of providing a groove or recess for the arm section and/or the body portion. The groove or recess may be formed by use of a disc cutter. This can enable the convenient formation of a groove or recess of pre-determined width and depth, hi such embodiments, the method may comprise the further step of applying filler material over the arm section or body portion to provide a smooth surface.

Preferably, the filler material is of sufficient viscosity to substantially hold its shape whilst curing thus allowing the groove or recess to be filled. Advantageously, the filler material is adapted to cure in the presence of water. The filler material may be an epoxy resin. If an epoxy resin adhesive is used to retain either the arm portion or the body portion in position, the filler material may be the same epoxy resin.

In accordance with a fifth aspect of the present invention there is provided a method of monitoring conditions within a sewer containing one or more cable guides according to the first aspect of the present invention, the method comprising monitoring the output signals generated by the one or more sensing elements of each cable guide to obtain an indication of conditions at various locations within the sewer.

The method of the fifth aspect of the present invention may incorporate any or all features of the first for aspects of the present invention as are desired or as are appropriate.

In order that the invention can be more clearly understood it is now described further below with reference to the accompanying drawings:

Figure 1 is a schematic view of the base portion of a sewer incorporating a flow channel;

Figure 2 shows one embodiment of a cable guide according to the present invention suitable for allowing a cable to enter/exit the flow channel of a sewer without substantially impeding the flow and incorporating a pair of sensing elements;

Figure 3 shows an intermediate stage in the process of installing a cable guide according to the present invention in a flow channel of a sewer;

Figure 4 shows a cable guide according to the present invention installed in the flow channel of a sewer;

Figure 5 shows a schematic block diagram of the circuitry controlling and monitoring the sensing elements in the above embodiments.

Referring now to figure 1, one form of sewer comprises a pipe having a bottom section 100 incorporating a flow channel 101 along which sewage flows. When there is a heavy flow load, the sewage can also flow over the banks 102 adjoining the flow channel 101.

Referring now to figure 2, one embodiment of a cable guide 110 is shown.

The cable guide 110 comprises a body section 111 and an arm section 112. In the present embodiment, the body comprises a panel 111 curved so as to be able to lie substantially flush with the walls of the flow channel 101 and the arm comprises a tube with an internal passage. The arm 112 projects from the body 111 and the passage within the arm 112 extends from an opening 113 provided in the body 111 to an opening 114 provided at the distal end of the arm 112. The openings 113, 114 and the passage within the arm 112 are of suitable dimensions to carry a cable 105. The body is also provided with a cable clip 115.

The cable guide 110 is formed from stainless steel. Accordingly, the cable guide 110 is able to resist decomposition by chemical or biological agents likely to be present within the sewer. In alternative embodiments, the cable guide 110 may be formed from any other suitable material.

The cable guide is further provided with first and second sensing elements

121, 122. The first sensing element 122 is a chemical sensor comprising a sensing element operable to output an electronic signal indicative of the presence of one or more substances. This sensing element 122 can thus be used to detect the presence of substances typical in effluent, providing a useful indication of the effluent

concentration of the flow. Additionally or alternatively, it can be sensitive to substances not normally present in the flow to provide an indication of a chemical spillage or of a flood event wherein oil etc from road surfaces is washed into the sewer.

The second sensing element 121 is a calorimetric sensing element operable to determine the flow height by reference to the heat lost in the upstanding portion of the sensing element 121. By monitoring the flow height, an advance indication of the existence of a flood condition or blockage may be obtained.

In alternative embodiments, the second sensing element 121 may take a different form. In one such example, the second sensing element may comprise a temperature sensor mounted on the upper surface of the body section 111. By monitoring the temperature variation at the bottom of the flow, an estimate of the variation in the flow depth can be made since deeper flows are typically cooler. A further alternative possibility for obtaining an estimate of flow depth would be to provide a pressure sensor on the upper surface of body section 111.

Referring now to figure 5 a block diagram of the control and monitoring circuitry of the sensing components is shown. The sensing elements 121, 122 are connected to a control element 123. Power may be provided by a suitable power source 126, which might be a rechargeable battery. A suitable energy scavenging means 127 may also be provided to extract energy from the flow or from any other source to recharge the battery 126.

The control element 123 is operable to receive the output from the sensing elements 121, 122 and pass it to a communication means 124 or a data storage means 125, as required. The communication means may be operable to transmit and/or receive signals over any suitable wired or wireless link.

The control element 123 may be operable to intermittently or continuously monitor the output values of sensing elements 121, 122 and either store data indicative thereof in the data storage means 125 or cause the communication means 124 to transmit it to external circuitry. In order to save power, the control element 123 may operate the communication means 124 less often than the data storage means 125. ha the event that a sensing element 121, 122 records a signal above or below specified thresholds, the control element 123 may be operable to operate the communication means 124.

The cable guide 110 is installed into the sewer by the process illustrated in figures 3 and 4. Firstly, it is determined at what location the cable 105 is to enter/exit the flow channel 101. At this location a groove 103 is cut into the banks 102 and the side of the flow channel 101. The groove 103 is sufficiently wide and deep to accept the arm 112. Epoxy resin of a type adapted to cure under water is applied to the undersides of the body 111 and the arm 112. The cable guide 110 is then placed in the flow channel 101 such that the arm 112 lies within the groove 103. Filler material 104, which may be the same epoxy resin used to secure the body 111 and arm 112. in position, is then applied to smooth over the top of arm 112, leaving opening 114 uncovered, so as to provide minimal impediment to flow along banks 102.

Once the cable guide 110 is installed, a cable 105 can be passed through the passage between openings 113 and 114.

By utilising a cable guide in this way, disruption to the flow within the channel 101 by the entrance or exit of the cable 105 is minimised. The cable 105 can be retained in position by the cable clip 115. This prevents a high point occurring in the cable 105 as it bends to enter opening 113. Additionally, the clip 115 restricts the lateral movement of the cable 105 prior to entering opening 113, preventing the cable 105 lying across the direction of flow. In this manner, the clip 115 helps to reduce the disruption to the flow caused by the entrance/exit of the cable 105.

The cable guide 110 may be applied to the sewer in wet or dry conditions, as long as a suitable adhesive is used. As the installation process has few steps, it can be completed in under 1 hour. Accordingly, the use of such cable guides 110 along with the laying of the cable 105 loose in the flow channel 101 provides a relatively inexpensive and relatively quick method of laying cables through sewers. Accordingly, this cable guide and method may be applied to constructing networks, such as data networks, by laying cables through sewers. An additional advantage of using the cable guide according to the present invention is that if a network cable needs to be removed, the cable guide 110 can be left in place and does not provide a significant impediment to flow along the flow channel 101. Alternatively, if a cable 105 is to be replaced, it is quick and convenient to remove the old cable 105 and insert a replacement cable 105.

Other potential variations of the form of the cable guide are described in our co-pending application WO2008/009964 the disclosure of which is wholly incorporated herein by reference.

It is of course to be understood that the invention is not to be restricted to the details of the above embodiments which have been described by way of example only.