LEAK DETECTION APPARATUS

Abstract: An apparatus comprising means (10) for detecting a leak of fluid from an appliance (2) and means (8) arranged to provide an alarm and/or to stop a supply of fluid (4) and/or to stop a supply of fluid (4) and/or electricity (6) to the appliance (2) in the event that a leak is detected by the detecting means (10).

Description: Leak Detection Apparatus The present invention relates to an apparatus for reducing the risk of flooding and/or electric shock resulting from a leak of fluid from an appliance and, in particular, to a leak of water from a mains-water fed, chilled-water dispenser. It is now commonplace to provide a chilled-water dispenser in the home or workplace, for dispensing drinking water . However, such dispensers are prone to leakages, which may cause flooding and can also increase the likelihood of electric shock where a dispenser is connected to a mains electricity supply, as is typically the case. Many types of chilled-water dispensers are fed from a bottled water supply and thus only a limited amount of water may leak from the dispenser. Such dispensers therefore tend to be chosen over dispensers fed from a mains water supply to reduce the risk of flooding. The economic benefits of mains-water fed dispensers are therefore presently not being fully realised. We have now devised an apparatus for reducing the risk of flooding and/or electric shock resulting from a leak of water from an appliance, the apparatus being particularly suitable for use with mains-water fed, chilled-water dispensers. According to a first aspect of the present invention, there is provided an apparatus comprising means for detecting a leak of fluid from an appliance and means arranged to provide an alarm and/or to stop a supply of fluid and/or electricity to the appliance in the event that a leak is detected by the detecting means. Thus by use of the apparatus, the risk of flooding and/or electric shock may be substantially reduced. The detecting means may comprise an electrical circuit, whose electrical resistance varies as a result of the conduction of electricity through fluid which may have leaked from the appliance, and means for detecting that variation in electrical resistance. The circuit may comprise a hygroscopic cable comprising a pair of sensing wires which are normally electrically isolated from one another along their length by a fluid permeable barrier material, the detecting means being arranged to detect any conduction which may occur between the two wires as a result of fluid leaking into the barrier material between the wires . The barrier material is preferably provided by respective fluid permeable sheaths applied around each of the sensing wires. The sheaths are preferably absorbent and are most preferably formed of paper. The cable preferably comprises a second pair of electrically insulated wires which are either connected at their distal ends to respective sensing wires, to form respective circuits for testing the integrity of the sensing wires, or are connected to one another at their distal ends, to form a circuit for detecting any break in the cable. Most preferably the cable comprises two pairs of insulated wires, one pair being connected at their distal ends to respective sensing wires and the other pair being connected to one another at their distal ends. A fluid permeable outer sheath is preferably applied around the wires of the cable. The outer sheath preferably comprises an inner layer of absorbent material, preferably paper, and an outer reinforcing layer of open-braided material, preferably nylon. The detecting means may instead comprise means for monitoring a supply of fluid to the appliance, for example to detect any drop in flow during operation of the appliance, which may be caused by a leak, or to detect any flow due to leakage when the appliance is not in use. In a first preferred embodiment of the present invention, the apparatus comprises a rigid plinth for supporting the appliance, the upper surface of the plinth being shaped to channel fluid leaking from the appliance to the detecting means . Preferably the detecting means are removably mounted below the plinth which is formed with an aperture for communicating fluid from its upper surface to the detecting means. The detecting means are therefore readily accessible, for example to dry them after a leak has been repaired. Preferably the detecting means comprise a pair of electrical contacts, between which an electrical current may flow through fluid having leaked from the appliance to complete an electrical circuit. Preferably the electrical contacts are provided in a recess in the upper surface of a removable tray, which recess normally underlies said aperture. Preferably the apparatus is arranged to provide an alarm and/or to stop a supply of fluid and/or electricity to the appliance in the event that the tray is displaced from its normal position, for example to be wiped dry once a leak has been repaired. The apparatus may comprise a sensor for detecting when the tray is displaced from its normal position, or the displacement of the tray may complete the electrical circuit. Preferably the upper surface of the plinth is of concave form, having said aperture formed at its base. In a second preferred embodiment of the present invention, the apparatus comprises a mat for supporting the appliance, the surface of the mat being shaped to channel fluid leaking from the appliance to the detecting means. In this second embodiment, the detecting means preferably comprise a hygroscopic cable which is embedded in and extends below the surface of the mat, the mat being formed with at least one aperture for communicating fluid from its upper surface to the cable. Preferably the upper surface of the mat is formed with a plurality of surface channels. Most preferably the upper surface of the mat is formed with a plurality of rectilinear surface channels, with respective apertures for communicating fluid from the upper surface of the mat to the cable preferably formed at the opposite ends of each channel . Preferably the hygroscopic cable extends around the periphery of the mat . According to a second aspect of the present invention, there is provided an appliance comprising means for detecting a leak of fluid therefrom and means arranged to provide an alarm and/or to stop a supply of fluid and/or electricity to the appliance in the event that a leak is detected by the detecting means . According to a third aspect of the present invention, there is provided an apparatus comprising a hygroscopic cable comprising a pair of sensing wires which are normally electrically isolated from one another along their length by a fluid permeable barrier material, and means arranged to detect any conduction which may occur between the two wires as a result of fluid leaking into the barrier material between the wires. According to a fourth aspect of the present invention, there is provided a safety arrangement for providing an alarm and/or for stopping a supply of fluid and/or electricity to an appliance in the event that a leak of fluid from the appliance is detected, wherein a hygroscopic cable encircles, at least partly, the base of the appliance for detecting said leak of fluid. According to a fifth aspect of the present invention, there is provided a hygroscopic cable comprising a pair of a pair of sensing wires which are electrically isolated from one another along their length by a fluid permeable barrier material . According to a sixth aspect of the present invention, there is provided a method for installing a safety arrangement for detecting a leak of water comprising providing a hygroscopic cable having a first pair of sensing wires which are normally electrically isolated from one another along their length by a fluid permeable barrier and a second pair of electrically insulated wires, cutting the cable to the required length and connecting the second pair of wires, at their distal ends, to respective sensing wires, to form respective circuits for testing the integrity of the sensing wires . According to a seventh aspect of the present invention, there is provided a method for installing a safety arrangement for detecting a leak of water comprising providing a hygroscopic cable having a first pair of sensing wires which are normally electrically isolated from one another along their length by a fluid permeable barrier and a second pair of electrically insulated wires, cutting the cable to the required length and connecting the second pair of wires to one another, at their distal ends, to form a circuit for detecting any break in the cable. Embodiments of the present invention will now be described by way of examples only and with reference to the accompanying drawings, in which: Figure 1 is a schematic view of a safety arrangement in accordance with the present apparatus; Figures 2 and 3 are respective isometric views of a first embodiment of detecting means in accordance with the present invention, showing a sliding tray thereof in retracted and extended positions; Figures 4 is an isometric, cut-away view of a second embodiment of detecting means in accordance with the present invention; Figure 5 is a section through a preferred hygroscopic cable arrangement; and Figures 6a to 6d are schematic diagrams showing how sensing means may be connected to the cable in various ways to detect certain conditions . Referring to Figure 1 of the drawings a chilled-water dispenser 2 is shown, to which a mains water supply 4 and electricity supply 6 are connected via a control unit 8. The control unit 8 is responsive to output signals from detecting means 10 to stop the supply of water and electricity to the dispenser 2 in the event that water leaking from the dispenser 2 is detected by the detecting means 10. A first preferred detecting means 10 is shown in Figure 2 and Figure 3 and comprises a plinth 12 for supporting the dispenser 2 and having a concave upper surface 14 for channelling any water that may leak from the dispenser to an aperture 16. The aperture 16 communicates with a compartment below the plinth 12, within which a tray 18 is slidably mounted. The upper surface of the tray 18 is formed with a recess 20 within which a pair of electrical contacts 22,24 are located. In normal use, with the tray 18 in its retracted position, the recess 20 underlies the aperture 16 so that any water leaking from the dispenser 2 will be channelled into the recess 20, thereby immersing the electrical contacts 22,24. The electrical contacts 22,24 form part of an electrical circuit which is closed when the contacts 22,24 are immersed in water, by an electric current flowing through the water. A portion of the plinth 12 has been cut away in Figure 3 to show a sensor 26 mounted at the rear of the tray, the sensor being connected to the control unit 8 to causes the latter to stop the supply of water and electricity to the dispenser 2 when the tray 18 is extended from the plinth 12 (as shown in Figure 3) , for example to wipe dry the recess 20 once a leak has been repaired. A second preferred detecting means 10 is shown in Figure 4 and comprises a flexible, rubber mat 28 for supporting the dispenser 2, the upper surface of the mat being formed with a plurality of rectilinear channels 30, partially shown in Figure 4. A portion of the mat has been cut away in Figure 4 to show respective apertures 32 at the opposite ends of each channel 30, which communicate with a passageway 34 extending around the perimeter of the mat 28 and through which a hygroscopic cable 36 is routed. The hygroscopic cable 36 forms part of an electrical circuit which detects any change in the conductivity in the cable caused by water entering the cable via the passageway 34 and one or other of the apertures 30. Whilst in Figure 4, a hygroscopic cable 36 is shown embedded in a mat, it would however remain in accordance with the present invention for the cable to be laid free of any support structure, for example around the base of the dispenser, around the perimeter of a room, or beneath the floor surface of a room, to detect water leaking from the dispenser. A preferred cable arrangement is shown in Figure 5 and comprises a pair of sensing wires 38, to which respective absorbent paper sheaths 40 are applied. The cable comprises a second pair of wires 42, the distal ends of which are connected to respective sensing wires 38, and third pair of wires 44, the distal ends of which are connected to one another. The second and third pairs of wires are each sheathed in an electrically insulating plastics material 46. A fluid permeable outer sheath 48 is applied around the three pairs of wires 38,42 44, the outer sheath comprising an inner layer 50 of absorbent paper material and an outer reinforcing layer 52 of open-braided nylon material . In normal use, sensing means 54 are connected between the proximal ends of the two sensing wires 38 (as shown in Figure 6a) , to detect any conduction between the wires, which may be indicative of water leaking into the cable. From time to time, the integrity of each of the sensing wires 38 may be tested, in turn, by connecting sensing means 54 between the proximal end of each sensing wire and the proximal end of the insulated wire 42 to which is it connected (as shown in Figures 6b and 6c) . Sensing means 54 are also permanently connected between the proximal ends of the interconnected insulated wires 44 (as shown in Figure 6d) to detect any decrease in conduction through those wires, which may be indicative of a break in the cable. The detecting means 10 may also or otherwise comprise means (not shown) for monitoring the supply of water to the appliance, for example to detect any drop in flow during operation of the appliance, which may be caused by a leak, or to detect any flow due to leakage when the appliance is not in use. In each case, the control unit 8 is arranged to respond to a failure of the detecting means 10, for example due to disconnection of the detecting means 10 from the control unit 8, by stopping the water and electricity supplies to the dispenser 2. In addition to, or as an alternative to, a control unit 8 for stopping the water and electricity supplies to the dispenser 2, visual and/or auditory alarm means (not shown) may be provided for indicating the detection of a leak, an extended tray and/or a fault condition. Also, whilst arrangements have been described for responding to a water leak from a chilled-water dispenser, the same detecting and control apparatus could be adapted for use with another type of appliance such as a domestic washing machine or dishwasher, and to respond to a leak of fluid other than water. The embodiments thus described provide an effective means for preventing the flooding of a building by a leaking appliance and for reducing the associated likelihood of electric shock.

Claims: Claims 1) An apparatus comprising means for detecting a leak of fluid from an appliance and means arranged to provide an alarm and/or to stop a supply of fluid and/or electricity to the appliance in the event that a leak is detected by the detecting means . 2) An apparatus as claimed in Claim 1, wherein the detecting means comprise an electrical circuit, whose electrical resistance varies as a result of the conduction of electricity through fluid which may have leaked from the appliance, and means for detecting that variation in electrical resistance. 3) An apparatus as claimed in Claim 2, wherein the circuit comprises a hygroscopic cable comprising a pair of sensing wires which are normally electrically isolated from one another along their length by a fluid permeable barrier material, and wherein the detecting means are arranged to detect any conduction which may occur between the two wires as a result of fluid leaking into the barrier material between the wires. 4) An apparatus as claimed in Claim 3, wherein the barrier material is provided by respective fluid permeable sheaths applied around each of the sensing wires. 5) An apparatus as claimed in Claim 4, wherein said sheaths are absorbent . 6) An apparatus as claimed in Claim 5, wherein said sheaths are formed of paper. 7) An apparatus as claimed in any of Claims 3 to 6, wherein the cable comprises a further pair of electrically insulated wires which are connected at their distal ends to respective sensing wires, to form respective circuits for testing the integrity of the sensing wires. 8) An apparatus as claimed in any of Claims 3 to 7, wherein the cable comprises a further pair of electrically insulated wires which are connected to one another at their distal ends, to form a circuit for detecting any break in the cable. 9) An apparatus as claimed in any of Claims 3 to 8, wherein a fluid permeable outer sheath is applied around the wires pf the cable. 10) An apparatus as claimed in Claim 9, wherein the outer sheath comprises an inner layer of absorbent material, and an outer reinforcing layer of open-braided material . 11) An apparatus as claimed in Claim 10, wherein said absorbent material comprises paper. 12) An apparatus as claimed in Claim 10 or Claim 11, wherein said open braided material comprises nylon material . 13) An apparatus as claimed in Claim 1, wherein the detecting means comprise means for monitoring a supply of fluid to the appliance. 14) An apparatus as claimed in Claim 13, wherein the monitoring means are arranged to detect any drop in flow due to leakage, during operation of the appliance. 15) An apparatus as claimed in Claim 13 or Claim 14, wherein the monitoring means are arranged to detect any flow due to leakage, when the appliance is not in use. 16) An apparatus as claimed in Claim 1, comprising a rigid plinth for supporting the appliance, the upper surface of the plinth being shaped to channel fluid leaking from the appliance to the detecting means. 17) An apparatus as claimed in Claim 16, wherein the detecting means are removably mounted below the plinth which is formed with an aperture for communicating fluid from its upper surface to the detecting means . 18) An apparatus as claimed in Claim 16 or Claim 17, wherein the detecting means comprise a pair of electrical contacts, between which an electrical current may flow through fluid having leaked from the appliance to complete an electrical circuit. 19) An apparatus as claimed in Claim 18, wherein the electrical contacts are provided in a recess in the upper surface of a removable tray, which recess normally underlies said aperture. 20) An apparatus as claimed in Claim 19, arranged to provide an alarm and/or to stop a supply of fluid and/or electricity to the appliance in the event that the tray is displaced from its normal position. 21) An apparatus as claimed in Claim 20, comprising a sensor for detecting when the tray is displaced from its normal position. 22) An apparatus as claimed in Claim 20, wherein displacement of the tray completes said electrical circuit. 23) An apparatus as claimed in Claims 17 or any of Claims 18 to 22, as appended to Claim 17, wherein the upper surface of the plinth is of concave form, having said aperture formed at its base. 24) An apparatus as claimed in Claim 1, comprising a mat for supporting the appliance, the surface of the mat being shaped to channel fluid leaking from the appliance to the detecting means. 25) An apparatus as claimed in Claim 24, wherein the detecting means comprise a hygroscopic cable which is embedded in and extends below the surface of the mat, the mat being formed with at least one aperture for communicating fluid from its upper surface to the cable. 26) An apparatus as claimed in any of Claims 25 or Claim 26, wherein the hygroscopic cable extends around the periphery of the mat . 27) An apparatus as claimed in any of Claims 24 to 26, wherein the upper surface of the mat is formed with a plurality of surface channels. 28) An apparatus as claimed in Claim 27, as appended to Claim 25 or Claim 26, wherein the plurality of surface channels comprise a plurality of rectilinear surface channels, with respective apertures for communicating fluid from the upper surface of the mat to the cable preferably formed at the opposite ends of each channel. 29) An apparatus comprising a hygroscopic cable comprising a pair of sensing wires which are normally electrically isolated from one another along their length by a fluid permeable barrier material, and means arranged to detect any conduction which may occur between the two wires as a result of fluid leaking into the barrier material between the wires. 30) An apparatus as claimed in Claim 29, wherein the barrier material is provided by respective fluid permeable sheaths applied around each of the sensing wires. 31) An apparatus as claimed in Claim 30, wherein said sheaths are absorbent. 32) An apparatus as claimed in Claim 31, wherein said sheaths are formed of paper. 33) An apparatus as claimed in any of Claims 29 to 32, wherein the cable comprises a further pair of electrically insulated wires which are connected at their distal ends to respective sensing wires, to form respective circuits for testing the integrity of the sensing wires . 34) An apparatus as claimed in any of Claims 29 to 33, wherein the cable comprises a further pair of electrically insulated wires which are connected to one another at their distal ends, to form a circuit for detecting any break in the cable. 35) An apparatus as claimed in any of Claims 29 to 34, wherein a fluid permeable outer sheath is applied around the wires of the cable. 36) An apparatus as claimed in Claim 35, wherein the outer sheath comprises an inner layer of absorbent material, and an outer reinforcing layer of open-braided material. 37) An apparatus as claimed in Claim 36, wherein said absorbent material comprises paper. 38) An apparatus as claimed in Claim 36 or Claim 37, wherein said open braided material comprises nylon material. 39) An appliance comprising means for detecting a leak of fluid therefrom and means arranged to provide an alarm and/or to stop a supply of fluid and/or electricity to the appliance in the event that a leak is detected by the detecting means. 40) A safety arrangement for providing an alarm and/or for stopping a supply of fluid and/or electricity to an appliance in the event that a leak of fluid from the appliance is detected, wherein a hygroscopic cable encircles, at least partly, the base of the appliance for detecting said leak of fluid. 41) A safety arrangement as claimed in Claim 40, wherein said hygroscopic cable comprises a pair of sensing wires which are normally electrically isolated from one another along their length by a fluid permeable barrier material, and wherein means are provided for detecting any conduction which may occur between the two wires as a result of fluid leaking into the barrier material between the wires . 42) A hygroscopic cable comprising a pair of sensing wires which are electrically isolated from one another along their length by a fluid permeable barrier material. 43) A hygroscopic cable as claimed in Claim 42, wherein the barrier material is provided by respective fluid permeable sheaths applied around each of the sensing ' wires . 44) A hygroscopic cable as claimed in Claim 43, wherein said sheaths are absorbent. 45) A hygroscopic cable as claimed in Claim 44, wherein said sheaths are formed of paper. 46) A hygroscopic cable as claimed in any of Claims 42 to 45, wherein the cable comprises a further pair of electrically insulated wires which are, or are arranged to be, either connected at their distal ends to respective sensing wires, to form respective circuits for testing the integrity of the sensing wires 47) A hygroscopic cable as claimed in any of Claims 42 to 46, wherein the cable comprises a further pair of electrically insulated wires which are, or are arranged to, be connected to one another at their distal ends, to form a circuit for detecting any break in the cable. 48) A hygroscopic cable as claimed in any of Claims 42 to 47, wherein a fluid permeable outer sheath is applied around the wires of the cable. 49) A hygroscopic cable as claimed in Claim 48, wherein the outer sheath comprises an inner layer of absorbent material, and an outer reinforcing layer of open-braided material . 50) A hygroscopic cable as claimed in Claim 49, wherein said absorbent material comprises paper. 51) A hygroscopic cable as claimed in Claim 49 or Claim 50, wherein said open braided material comprises nylon material. 52) A method for installing a safety arrangement for detecting a leak of water, comprising, providing a hygroscopic cable having a first pair of sensing wires which are normally electrically isolated from one another along their length by a fluid permeable barrier and a second pair of electrically insulated wires, cutting the cable to the required length and connecting the second pair of wires, at their distal ends, to respective sensing wires, to form respective circuits for testing the integrity of the sensing wires. 53) A method for installing a safety arrangement for detecting a leak of water, comprising providing a hygroscopic cable having a first pair of sensing wires which are normally electrically isolated from one another along their length by a fluid permeable barrier and a second pair of electrically insulated wires, cutting the cable to the required length and connecting the second pair of wires to one another, at their distal ends, to form a circuit for detecting any break in the cable.

Inventors: BROOKS ADRIAN EDWARD, BROOKS, ADRIAN, EDWARD
Applicants: B W TECHNOLOGIES LTD, BROOKS ADRIAN EDWARD, B W TECHNOLOGIES LIMITED, BROOKS, ADRIAN, EDWARD
Application year: 2001
Main classification: G01M3
IPC codes: A47L15, D06F39, G01M3