Conductive film for leak detection

Abstract

Described herein is a conductive film (90) for leak detection. The conductive film (90) comprises a membrane having a mesh structure comprising a plurality of holes (91) that are configured to provide drainage through the membrane. The film (90) is formed of a polymer. The polymer is doped with at least one conductive material to enable an electrical current to pass through the film (90). A system and method are also provided.

Description

[0001] MM

[0002] Conductive film for leak detection

[0003] Technical field

[0004] The present invention relates to a conductive film, for example, as may be used to assist in the detection of leaks, such as leaks in waterproofing membranes or geomembranes, such as an isolation layer placed for example at the bottom, walls or caps of landfills for industrial, household or other waste, or at the bottom, walls or dams of reservoirs or retention basins, or canals, or heap leach mines, or under roof membranes, or gas membranes under buildings, or any other equivalent application.

[0005] Background

[0006] It is known to place geotextiles at the bottom of landfills or basins, providing either drainage or protective functions.

[0007] In particular, document EP-A-0418209 describes a method for detecting leaks, in particular leaks in an isolation layer, in which an electro-conductive layer in the form of a geotextile provided with conductive threads is applied under the isolation layer and to which an electrical voltage is applied at least between two conductive threads, so as to determine the intensity of the current and / or the resistance between the two threads. It should be noted, however, that this detection method will only work if the soil is already moist, i.e. if a leak has already occurred; this method cannot be applied to dry soil.

[0008] Also known from publication WO94 / 02822 is a device and a method for inspecting the status of an isolation layer separating an object to be insulated from its environment and which consists in providing an active electrode arranged outside the isolation zone and at least one sensitive electrode arranged either above or below said isolation layer, a device comprising a source of electrical energy making it possible to connect said active electrode to the sensitive electrode(s), making it possible to measure and / or record the values of the electric field created in the zone close to the sealing layer. In this paper, the sensitive electrodes are arranged directly on the ground in the area close to the sealing layer.

[0009] On the other hand, for several years now, there has been a demand to improve the waterproofing of civil engineering structures by proposing a double membrane waterproofing system, which comprises two membranes separated by an intermediate layer which is usually made of gravel, clay, geotextile, or more recently drainage geocomposites.

[0010] This type of product helps increase safety by reducing the risk of an accidental leak into the environment. This type of protection is particularly chosen when it is necessary to avoid any contamination outside the structure.

[0011] Document EP-A-0 418 209 describes a method of detecting leaks, in particular leaks in an isolation layer, in which method a geotextile enhanced to be electro-conductive layer being provided with substantially parallel conductive wires is applied under the insulating layer, an electrical voltage is applied between at least two conductive wires, and the current intensity and / or the resistance between the two wires is determined. This document EP-A-0 418 209 also relates to the geotextile used in the method. This geotextile is provided with substantially parallel conducting wires. It may be either a fabricMM

[0012] or a nonwoven material. No further details concerning the characteristics of this geotextile appear in this document.

[0013] WO88 / 06929 relates to the structure of a bed such as the bottom of a waste landfill, comprising a double liquid-tight membrane, with an upper membrane and a lower membrane. Between these two membranes, an intermediate layer of a porous material is present, inside of which there are disposed electrical humidity detection means intended to detect possible leaks of liquid through said upper membrane. It is further specified that the upper and lower membranes may be plastic sheets. Also, it is disclosed that the porous material may be sand or gravel.

[0014] WO 94 / 02822 discloses a device for inspecting the integrity state of an isolation layer separating an isolated object from its environment, wherein: at least one active electrode is placed on the outer side and / or the inner side of the isolation layer; at least one sensitive electrode is placed in proximity to the isolation layer; and at least one active electrode or at least one sensitive electrode is placed inside the isolation layer.

[0015] The present invention aims to provide a new type of electro-conductive layer that uses a conductive film instead of a multi-layered electro-conductive geotextile of geomembrane for detecting and / or monitoring leaks occurring under engineering structures, such as landfills and / or equipped basins.

[0016] Summary

[0017] The present invention provides an electro-conductive layer in the form of a conductive film rather than a multi-layered electro-conductive geotextile or geomembrane. As used herein, the terms “conductive film” and “electro-conductive film” or “electro-conductive layer” may be used interchangeably. Electro-conductive geotextiles or geomembranes were originally invented to provide a composite product where both a geotextile and an electro-conductive layer were required simultaneously, however this is not always the case and sometimes the electro-conductivity is required but the geotextile’s properties are superfluous (e.g. between two geomembranes, in a double lining system). Geotextiles are normally specified for their drainage and protective properties (e.g. keeping stones in the ground from making direct contact with the geomembrane I waterproofing membrane I gas proofing membrane that can cause damage to them from the underside). In many cases the geotextile is not required at all but has become a default feature of electro-conductive layers. In addition, geotextiles tend to be less robust in terms of longevity than the geomembranes I membranes themselves, compared with conductive films, as described herein.

[0018] The present invention relates to a conductive film for detecting leaks. The conductive film may be used to monitor structures equipped with a double sealing membrane i.e., the conductive film may be located with drainage geocomposites that facilitate removal of liquids within interstitial space (the conductive film may be above and / or below, or even between first and second membranes forming a double sealing membrane. The conductive film for leak detection comprises a membrane. The membrane has a mesh structure comprising a plurality of holes. The plurality of holes is configured to provide drainage through the membrane. For example, the holes may provide drainage of water orMM

[0019] discharge liquids. The film is formed of a polymer. The polymer may be any suitable polymer that can withstand the required conditions, relevant examples as will be known to the skilled person. The polymer is doped with at least one conductive material to enable an electric current to pass through the film.

[0020] Advantageously, the conductive film may enable leaks to be detected by monitoring changes in the flow of electricity across the film, for example. This may enable leaks in a double sealing membrane to be identified. Further advantageously, the conductive film of the present invention does not require a separate carrier to support it, for example, lamination to a geomembrane or geotextile layer. As a result, the present invention may enable the production of simpler and more cost-effective installations on site, particularly where there is no intrinsic need for the specific properties provided by a geotextile layer. Further advantageously, providing a conductive film that is based on a plastic film rather than a geotextile, may provide enhanced longevity.

[0021] The conductive film may be conductive all the way through the film. The conductive film may be also be conductive across its major surfaces.

[0022] Advantageously, this may improve the ability of the conductive film to be used for leak detection. The conductive film may have a single layer or a monolayer construction. In other words, the conductive film may be used without the need to also provide geotextile or geomembrane layers.

[0023] Advantageously, the conductive film may be used to perform leak detection without the need to also provide geotextile or geomembrane layers.

[0024] The conductive film may be doped with carbon, conductive graphene, and / or a metallic additive. The metallic additive may be a metal having suitable electrically conductive properties. The metallic additive may be at least one of zinc, aluminium, titanium, silver, copper, steel, and / or stainless steel, preferably 316L stainless steel.

[0025] Advantageously, these materials may provide the conductive film with suitable electroconductivity to enable, enhance, or augment electrical leak detection.

[0026] The conductive film may comprise a resistivity of less than 105Ohm / square. Preferably, the conductive film may comprise a resistivity from 500 Ohms / square up to 5000 Ohm / square. More preferably, the conductive film may comprise a resistivity from 1000 up to 2000 Ohm / square.

[0027] Advantageously, this arrangement may provide a resistivity and associated conductivity that is sufficient to enable the detection of leaks when using the electro-conductive film. Further advantageously, conductive film may produce a more homogenous electric field due to the thickness of the conductive film (see below) and its resistivity.The mesh structure of the electro-conductive film may comprise from at least 5 holes per square metre up to 5000 holes per square metre, such as from at least 100 to up to 300 holes per square metre, preferably substantially 150 holes per square metre. Each hole of the plurality of holes may have a diameter from at least 0.01 mm up to 100 mm, preferably 10 mm.

[0028] Advantageously, the holes may provide adequate drainage of the liquid and / or gas present in the environment of the insulation layer. Further advantageously, the use of a mesh structure mayMM

[0029] provide improved strength, allowing the conductive film to be provided without a supporting geotextile for reinforcement.

[0030] The holes of the plurality of holes may be square or circular. Advantageously, circular holes may provide improved strength.

[0031] The membrane of the conductive film may be reinforced or unreinforced, for example to provide improved structural stability. The membrane may be made of at least one of polyethylene, polypropylene, polyvinylchloride (PVC), thermoplastic polyolefin, ethylene vinyl alcohol (EVOH), polytetrafluoroethylene (PTFE), and / or polyamide.

[0032] Advantageously, these materials may be non-conductive. Further advantageously, these materials may be easily formed into a membrane using known methods. Further advantageously, by providing an unreinforced conductive film, a simpler and cheaper electro-conductive layer may be provided to enhance and augment the leak detection process. This may improve the longevity of the electro-conductive layer by reducing the likelihood disintegration during use, for example, when compared with geotextile products.

[0033] The conductive film may comprise at least one additive. The additive being it least one of: a UV stabiliser; a flame retardant; an antioxidant; an antimicrobial; a stabilizer; a plasticiser, and / or an anti-blocking additive. The use of a UV stabiliser additive may prevent degradation of the film due to UV light exposure. The use of a flame-retardant additive may slow the spread of fire and reduce the rate of burn of the film if exposed to fire. The use of antioxidant additives may prevent aging and oxidation. The use of antimicrobial additives may prevent or limit bacterial growth on the surface of the film. The use of stabilisers may improve the durability of the film in harsh environments. The use of plasticisers may improve the flexibility of the film, particularly when moulding, shaping, and thermoforming the film. The use of anti-blocking additives may reduce the friction between adjacent layers of film.

[0034] Advantageously, the use of at least one or more additive may enhance certain properties or characteristics of the film. The use of additives may provide improved longevity than is possible for geotextile products.

[0035] The conductive film maybe reinforced or unreinforced, reinforcement can be a mesh like material or a woven fabric material, made of fibres like glass, carbon, polyester, string, or metallic wire, that is embedded within the plastic to significantly increase its strength, tear resistance, and overall durability, where metallic wire is used this may be at least one of zinc, aluminium, titanium, silver, copper, steel, and / or stainless steel, preferably 316L stainless steel.

[0036] The conductive film may have a thickness from at least 1 pm up to 2000 pm, such as from at least 100 pm up to 200 pm, such as from at least 120 pm up to 150 pm, preferably substantially 120 pm.

[0037] Advantageously, the film may be lightweight and may be formed using a minimal amount of material, whilst retaining damage resistant properties. Further advantageously, the film is 100%MM

[0038] conductive film and no lamination, needle punching, gluing to a geotextile carrier or co-extruded non-electro-conductive layer is required, as such, the longevity of the conductive film can be improved. Further advantageously, conductive film may produce a more homogenous electric field due to the thickness of the conductive film and its resistivity (see above).

[0039] The conductive film may have a density from at least 1 g / m2up to 1000 g / m2, such as from at least 50 g / m2up to 150 g / m2preferably substantially 94 g / m2.

[0040] Advantageously, densities within this range may provide preferably handling characteristics, and robustness in the suggested use cases discussed herein.

[0041] The conductive film may further comprise an adhesive backing. The adhesive backing may be provided on at least one side of the conductive film. The adhesive backing may be configured to facilitate adhesion of the conductive film to a surface. For example, the adhesive used in the adhesive backing may be a contact adhesive or another suitable adhesive, preferably butyl adhesive, or polymer modified bitumen adhesive. Advantageously, the use of a butyl adhesive may provide more robust and longer lasting adhesion.

[0042] Advantageosuly, the use of an adhesive backing may enable the conductive film to be attached to a variety of different surfaces. Further advantageously, the adhesive backing may improve the ease with which the conductive film can be installed, for example, on vertical walls.

[0043] The conductive film may further comprise a removable backing sheet. The removable backing sheet may be release paper. The removable backing sheet may be located on the same side of the conductive film as the adhesive layer. The backing layer may be provided to cover the conductive film. The backing layer may be configured to be removed from the conductive film to expose the adhesive backing for adhesion to a surface. For example, during fitting, the backing layer may be peeled away from the conductive film to expose the adhesive backing, to facilitate adhesive attachment of the conductive film to a surface. For example, the adhesive backing may enable the conductive film to be adhered to concrete, insulation board, timber sheets, or other insulation materials, waterproof membranes, and drainage composites.

[0044] Advantageously, the backing layer may prevent unintended adhesion of the adhesive layer to surfaces during fitting, until the backing layer has been removed. This may further improve the ease with which the conductive film can be installed.

[0045] The adhesive backing may be configured to electrically isolate the conductive film is from the surface. In in other words, the adhesive backing, that is located on at least one side of the conductive film, may electrically isolate the conductive film from a surface that the conductive film is adhered to.

[0046] Further advantageously, this may enable more effective leak detection and location. Relevant methods of performing leak detection are described in WO2016 / 001639A1 (A Sensor and System for Monitoring Integrity of a Waterproofing System or Membrane), in which the measurement of a current is used to determine watertightness / gas-tightness.MM

[0047] The conductive film may be substantially resistant to burnouts when electrically charged. Advantageously, this may improve the longevity of the conductive film. Advantageously, this may improve the resistance of the conductive film to power surges and the like.

[0048] The present invention also relates to a system. The system comprises the conductive film as described herein. The system further comprises an array of sensing electrodes connected to an active electrode arranged external to the conductive film. The system further comprises a controller, configured to monitor the flow of electricity in the conductive film between the array of sensing electrodes. The controller is configured to detect at least one leak based on a change in the flow of electricity in at least a portion of the conductive film. The controller may be a measuring and recording device. The system may comprise a double sealing membrane arranged to enclose the conductive film.

[0049] Advantageously, the system may use the conductive film to detect leaks based on changes in electrical flow, or conductivity. The system may enable determination of where a leak has occurred within the conductive film or the double sealed membrane.

[0050] The present invention further relates to a method of detecting leaks. The method uses the conductive film and / or system as described herein. The method may involve monitoring the electrical flow and / or conductivity of a conductive film. The method may further involve comparing an electrical flow, and / or a conductivity measurement with a baseline electrical flow, and / or conductivity measurement. The method may further involve identifying a change in electrical flow, and / or conductivity in at least a portion of the conductive film that is indicative of a leak. The method may further involve identifying the location of a leak based on measurement data received from an array of sensitive electrodes spread across the conductive film.

[0051] Advantageously, the method may be used to detect leaks, such as in roofs, landfills for industrial, household or other waste, or at the bottom of reservoirs, such as in floating or suspended covers, or in buildings, or dams, or mining heap leach fields, or retention basins, or any other equivalent application.

[0052] The present invention also relates to a method of manufacturing the conductive film as described herein, using blow film extrusion or flat die film extrusion. The conductive film is preferably not produced via co-extrusion. Therefore, the cost of producing the conductive film can be reduced.

[0053] Manufacturing of the conductive film by blow film extrusion may involve the steps of: providing pellets of a polymer; melting the polymer pellets to form a molten polymer; extruding the molten polymer through a circular die to form a tube of molten polymer; blowing air into the centre of the tube of molten polymer, thereby expanding the extruded polymer into a bubble of extruded polymer; cooling the bubble to solidify the polymer; and flattening the cooled extruded polymer into a film using a set of rollers to create a continuous film. Using this process, the thickness of the film may be controlled by adjusting the extrusion speed, amount of air flow when forming the bubble, and by adjusting the die size.

[0054] Manufacturing of the conductive film by flat die film extrusion may involve the steps of: providing pellets of a polymer; melting the polymer pellets to form a molten polymer; extruding the molten polymerMM

[0055] through a flat die to form a flat polymer web; the flat polymer web is cooled and solidified using cooling rollers to form a sheet.

[0056] Irrespective of the method of manufacture used, once the film has been formed and flattened, a plurality of holes may be introduced into the film by a die stamp or similar hole preparation process, such as drilling through the whole roll to its core at the desired centres after winding of the film into a roll. The film may be folded lengthways to produce films having a greater width. Alternatively, the film may be cut before winding to produce narrow widths.

[0057] Advantageously, the film may be produced using production processes that can be achieved by plastic film producers using existing equipment and known techniques.

[0058] In addition to the methods described above, the conductive film described herein may further be used as a reference electric pole, for example, for use in arc testing and dipole surveying.

[0059] The conductive film may be used to perform permanent monitoring.

[0060] Brief description of the figures

[0061] The present invention will be better described with the aid of the various figures which follow, in which:

[0062] Figure 1 represents a cross-sectional view of a landfill in which the leak detection and / or monitoring method according to the invention will be used.

[0063] Figure 2 represents a detailed view of a conductive film of the present invention.

[0064] Figure 3 represents an exploded perspective view of a conductive film according to the present invention.

[0065] Figure 4 represents an exploded perspective view of a conductive film including.

[0066] Detailed Description

[0067] The conductive film according to the present invention can be applied to the monitoring of an isolation layer, as shown in Figure 1 .

[0068] The conductive film could also be applied to monitoring a water retention basin, for example those present along roads, or even chemical liquid retention basins in the case of use on industrial sites. Other applications may also be envisaged within the framework of the present invention, for example the detection and / or monitoring of leaks which may occur in a tunnel equipped with a double sealing membrane comprising the conductive film discussed herein, these leaks being able to be due to ground movements for example. We can also mention a recreational body of water provided with a double waterproofing membrane comprising the conductive film, which aims to avoid any contamination of the environment, for example nearby water tables or in regions or with liquids such as pregnant solutions (a term used in the mining industry for cyanide with gold suspended inside from the heap leaching process) where the stored water / liquid / liquor is so valuable it must be retained.MM

[0069] Typically, a landfill is equipped on the side walls and bottom with a complex made up of one or more geotextiles acting as isolation and possibly allowing adequate drainage of the liquid and / or gas present in the environment of the isolation layer.

[0070] Figure 1 shows a landfill 1 in which a sealing layer 3 has been placed, consisting of membranes 5, 7 between which is placed the conductive film disclosed herein, the conductive film is arranged to enable the measurement of an electric field, thereby making it possible to detect the presence of a leak and / or monitor the sealing of layer 3.

[0071] As referred to herein, the term "sealing membrane" means a waterproof covering with a thickness greater than 0.2 mm and which has sufficient resistance to perforation. This waterproof sealing membrane can be made of EVOH, PVC, very low density, low density or even high-density polyethylene, or even polypropylene. It is also possible to consider using a bituminous sealing membrane.

[0072] According to Figure 1 , the upper sealing membrane 5 is in direct contact with the liquids present in the discharge, while the lower sealing membrane 7 adheres to the surrounding environment.

[0073] The conductive film forms an intermediate layer 9 between the two sealing membranes 5, 7. A network of sensitive electrodes 100 is provided which directly cover this intermediate layer 9.

[0074] According to the state of the art, this intermediate layer 9 usually consists of earth, clay or gravel. On the other hand, provision has been made for the placement of a so-called active electrode 102 arranged outside the sealing zone and which is intended to allow the measurement and / or recording of a value relating to the electric field created between the active electrode 102 and the sensitive electrode(s) 100. A measuring and recording device 110 is also provided. The measuring and recording device may also be referred to as a controller.

[0075] The conductive film 90 can be placed between the first and second sealing membranes 5, 7, and in which the sensitive electrodes 100 are included.

[0076] A first example of such a conductive film 90 is illustrated in Figure 2, in which a conductive film 90 is provided between first and second sealing membranes 5, 7. The film forms a membrane having a mesh structure comprising a plurality of holes 91 (discussed below). The holes 91 are configured to provide drainage through the membrane. The conductive film 90 is formed of a polymer that is doped with a conductive material to enable an electric current to pass through the film e.g., between the sensitive electrodes 100, discussed above. The conductive film 90 comprises a resistivity of less than 105Ohm / square in three directions (surface and from top to bottom I through, i.e. on the upper or lower surface and from the upper to the lower surface), such as a resistivity of around 103Ohm / square. Therefore, a square piece of the conductive film 90 may have a resistance of between 1 ,000 to 2,000 Ohms between opposite edges. The polymer is used to form the film, which may be reinforced or unreinforced, is one of polyethylene, polypropylene, polyvinylchloride, thermoplastic polyolefin, ethylene vinyl alcohol, polytetrafluoroethylene, and / or polyamide. Where polyethylene is used, the polymer is one of high-density polyethylene (HDPE), medium-density polyethylene (MDPE), low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), very low-density polyethylene (VLDPE), or ultra low-density polyethylene (ULDPE). The conductive film 90 has a thickness of substantially 120 pm. The conductive film 90 comprises a density of substantially 94 g / m2.MM

[0077] Figure 3 shows further example of the same conductive film 90, in which a conductive film 90 is provided between first and second sealing membranes 5, 7. As shown in Figure 3, the conductive film 90 comprises a sheet like structure having a plurality of holes or openings across its surface. The conductive film 90 comprises substantially 200 holes per square metre. Each of the holes 91 comprises a diameter of substantially 10 mm. The holes enable drainage of liquids and gases through the conductive film 90. Figure 3 is not to scale.

[0078] The use of a conductive film as described above combined with a network of electrodes will allow permanent control to be obtained, and therefore adequate monitoring, to avoid and prevent any risk of significant leakage.

[0079] A system can be provided including a geotextile comprising at least the first and second sealing membranes 5, 7 and a conductive film 90, and an array of electrodes 100 connected to an active electrode 102 arranged external to the conductive film 90. The electrodes are sensing electrodes 100. The system includes a controller 110 that monitors the conductivity of the conductive film 90. The controller 110 is arranged to detect a leak based on a change in conductivity in at least a portion of the conductive film 90. Such a leak can occur when, for example, one of the sealing membranes 5, 7 of the double sealing membrane is pierced, torn, or otherwise split open such that liquid can flow into the space between the sealing membranes 5, 7.

[0080] Particularly advantageously, it is found that this process is independent of soil conditions, i.e. whether the soil is wet or not, and works particularly well in a dry environment, because the required conductivity comes from the conductively doped polymer film, and not from the wet soil environment.

[0081] Figure 4 shows a further example of a conductive film 90, in which a conductive film 90 is substantially as described in relation to claim 3. However, in this example, the conductive film 90 further comprises an adhesive backing or adhesive layer 92. The adhesive backing 92 comprises an adhesive sufficient to enable attachment of the conductive film 90 to a surface, such as concrete, insulation board, a waterproof membrane, or a drainage composite. Of course, the adhesive backing 92 may facilitate adhesion of the conductive film 90 to various other types of surfaces, depending on the environment in which the conductive film 90 is to be used.

[0082] As Figure 4 also shows, the conductive film 90 may further comprise a backing layer 93. The backing layer 93 is located on the same side of the conductive film 90 as the adhesive layer 92. The backing layer 93 is arranged to cover the adhesive layer 92. The backing layer 93 is removable from the adhesive layer 92. In use, the backing layer 93 can be removed from the conductive film 90 to expose the adhesive layer 92. By exposing the adhesive layer 92 in this way, the adhesive layer 92 may be used to adhere the conductive film 90 to a surface.

[0083] The conductive film may be formed in sections, such as in square sections, also referred to as tiles. A plurality of conductive film sections may be connected by sewing. For example, a plurality of conductive film tiles may be combined to form a larger sheet of conductive film. The combined plurality of conductive film tiles may be provided with non-conductive borders therebetween. Alternatively, the conductive film sections may be attached to a backing layer to form a conductive geotextile section. A plurality of these conductive geotextile sections may then be connected together to form a larger conductive geotextile sheet. The combined plurality of conductive geotextile sections may be providedMM

[0084] with non-conductive borders therebetween. The plurality of conductive geotextile sections may be connected by sewing. For example, the plurality of conductive film tiles or conductive geotextile sections may be connected, via sewing, using a computer numerical control (CNC) sewing apparatus.

[0085] Example

[0086] In a preferred embodiment, the conductive film 90 has a thickness of 120 pm ± 5%, measured in accordance with ISO 4593. The conductive film 90 has a resistivity of 1-2 x 103Q / square, measured in accordance with EN IEC 61340. The conductive film 90 has a density of 0.96 - 0.98 g / cm3, measured in accordance with EN ISO 1183. The conductive film 90 has a break strength of 8.5 MPa, measured in accordance with EN ISO 527-3. The conductive film 90 has a break elongation of 300%, measured in accordance with Test type 5. The conductive film 90 has a tear resistance of 90 N / mm, measured in accordance with ISO 34-1. The conductive film 90 has a puncture resistance of 180 N, measured in accordance with EN ISO 12236. The conductive film 90 has an Elmendorf tear resistance in the machine direction of 7000 Nm, measured in accordance with ASTM D 1922. The conductive film 90 has an Elmendorf tear resistance in the cross direction of 15000 Nm, measured in accordance with ASTM D 1922. The conductive film 90 has an oxidation induction time (OIT) of > 100 min, measured in accordance with ASTM D8117. The conductive film 90 has a high-pressure oxidation induction time (HPOIT) of measured in accordance with ASTM D5885. The conductive film 90 comprises openings having a diameter of 10 mm, measured in accordance with EN ISO 12956.

Claims

MMCLAIMS1. A conductive film for leak detection, comprising:a membrane having a mesh structure comprising a plurality of holes that are configured to provide drainage through the membrane;wherein the film is formed of a polymer, the polymer being doped with at least one conductive material to enable an electric current to pass through the film.

2. The conductive film of claim 1 , wherein the conductive film is doped with at least one of carbon, conductive graphene, and / or a metallic additive.

3. The conductive film of claims 1 or 2, wherein the conductive film comprises a resistivity of less than 105Ohm / square.

4. The conductive film of claims 3, wherein the conductive film comprises a resistivity of 1000 to 2000 Ohm / square.

5. The conductive film of any preceding claim, wherein the mesh structure comprises at least 5 holes per square metre up to 5000 holes per square metre, preferably substantially 150 holes per square metre.

6. The conductive film of any preceding claim, wherein each hole of the plurality of holes has a diameter of at least 0.01 mm upto 100 mm, preferably substantially 10 mm.

7. The conductive film of any preceding claim, wherein the holes of the plurality of holes are square or circular.

8. The conductive film of any preceding claim, wherein the membrane is reinforced or unreinforced and made of at least one of polyethylene, polypropylene, polyvinylchloride, thermoplastic polyolefin, ethylene vinyl alcohol, polytetrafluoroethylene, and / or polyamide.MM9. The conductive film of any preceding claim, wherein the film comprises at least one additive, the additive being it least one of: a UV stabiliser; a flame retardant; an antioxidant; an antimicrobial; a stabilizer; a plasticiser, and / or an anti-blocking additive.

10. The conductive film of any preceding claim, wherein the conductive film has a thickness of at least 1 pm up to 2000 pm, preferably substantially from at least 120 pm up to 150 pm.

11. The conductive film of any preceding claim, wherein the conductive film has a density at least 1 g / m2up to 1000 g / m2, preferably substantially 94 g / m2.

12. The conductive film of any preceding claim, wherein the conductive film comprises an adhesive backing on at least one side, the adhesive backing being configured to facilitate adhesion of the conductive film to a surface.

13. The conductive film of claim 12, wherein the conductive film further comprises a removable backing sheet configured to be removed from the conductive film to expose the adhesive backing for adhesion to a surface.

14. The conductive film of claims 12 or 13, wherein the adhesive backing is configured to electrically isolate the conductive film is from the surface.

15. A system comprising:the conductive film of any one of claims 1-14; andan array of sensing electrodes connected to an active electrode arranged external to the conductive film; anda controller, configured to monitor the flow of electricity and / or conductivity in the conductive film between the array of sensing electrodes, andwherein the controller is configured to detect at least one leak based on a change in the flow of electricity and / or conductivity in at least a portion of the conductive film.

16. A method for detecting leaks using the conductive film of any of claims 1-14 or the system of claim 15.MM17. A method of manufacturing the conductive film of any one of claims 1-14, using blow film extrusion, coextrusion, lamination, or flat die film extrusion.

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