METHOD FOR LOCATING A LEAK IN A WATER SUPPLY NETWORK

Abstract

A method for locating a leak (19) in a water supply network with a water source (11) and one or more water consumption meters (21, 22) on the consumer side. The method includes calculating a length of the pipe (17) between the consumption meter (21) and the leak (19) location based on a temporal temperature curve and a quantity of water flowing through the at least one consumption meter (21).

Claims

1. A method for locating a leak in a water supply network, the network comprising at least one water source and one or more electronic water consumption meters on a consumer side, the method comprising the steps of: calculating a length of a pipe between at least one of the one or more consumption meters and a leak position based on a temporal temperature curve and a quantity of water flowing through the at least one of the one or more electronic water consumption meters.

2. A method according claim 1, wherein before calculating the length L of the pipe between the at least one of the one or more electronic water consumption meters and the leak location based on the temporal temperature curve and the quantity of water flowing through this at least one consumption meter, an acoustic leak detection is conducted using the at least one of the one or more electronic water consumption meters.

3. A method according claim 1, wherein the temperature of the water is captured by a temperature sensor arranged in or connected to the consumption meter.

4. A method according to claim 1, wherein the temperature of the water is captured by measuring the speed of sound in the fluid inside the at least one of the one or more electronic water consumption meters and calculating the temperature based on the measured speed.

5. A method according to claim 1, wherein the flow in the pipe is stopped for a period of time before the temporal temperature curve of the water flowing through the at least one of the one or more electronic water consumption meters is determined.

6. A method according to claim 1, wherein the ambient temperature of the at least one of the one or more electronic water consumption meters is captured.

7. A method according to claim 5, wherein the period of time of stopping corresponds at least to a time which is needed to adapt a temperature of the water in the pipe leading to the consumption meter to a temperature of the surroundings of the pipe.

8. A method according to claim 1, wherein a jump in temperature in the temporal temperature curve is detected, the length of the pipe between the leak and the consumption meter is calculated based on a cross-section of the pipe and a quantity of water that has flown through the at least one of the one or more electronic water consumption meters during a time between starting of the flow and the detection of the temperature jump.

9. A method according to claim 1, wherein the calculated length of the pipe is modified by a compensation factor, said compensation factor relating to one or more of the following: a length of the pipe from the at least one of the one or more electronic water consumption meters to an outer wall of a house; and deviations of a pipe routing from a straight line between a main distribution pipeline and the house.

10. A method according to claim 1, wherein the leak location is triggered by an acoustic leak detection by the consumption meter.

11. A consumption meter in a water supply network, the network comprising at least one water source and the ultrasonic consumption meter as one or more electronic water consumption meters on a consumer side, the ultrasonic consumption meter comprising: means for locating the leak in the water supply network, which is configured to calculate a length of a pipe between the ultrasonic consumption meter and a leak position based on a temporal temperature curve and a quantity of water flowing through the ultrasonic consumption meter.

12. A consumption meter according claim 11, further comprising temperature determination means for determining a temperature of the water flowing through the consumption meter and/or an ambient temperature.

13. A consumption meter according to claim 12, wherein the temperature determination means comprises a temperature sensor for sensing the temperature of the consumption meter and/or a temperature of the surroundings of the consumption meter.

14. A consumption meter according to claim 12, wherein the meter is an ultrasonic consumption meter and the temperature determination means determines the temperature of the water flowing through by measuring the speed of sound in the water.

15. A consumption meter according to claim 11, further comprising an electrically controlled shutoff valve in a pipe inside or adjacent to the consumption meter.

16. A consumption meter according to claim 11, wherein the means for locating the leak is part of control electronics forming a part of the consumption meter.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In the drawings:

[0028] FIG. 1 is a view of a very simplified form of a water supply network;

[0029] FIG. 2 is a view that illustrates a temporal temperature curve captured by a consumption meter; and

[0030] FIG. 3 is a view that illustrates a simplified water supply network with several consumers and consumption meters and a leak which has to be located.

DESCRIPTION OF PREFERRED EMBODIMENTS

[0031] In FIG. 1 the principle of different temperatures in a water supply network 1 is shown in a very simplified schematical drawing. There is a main line 2 of the grid 1 with flowing water inside of a low temperature for example 12° C. As there is a big volume flowing through the main line 2 this temperature is nearly constant.

[0032] From this main line 2 secondary lines 3 branch off. These secondary lines lead to consumers, for example houses. Especially if there is little or no consumption on the consumption side for example in the night, the water temperature in the secondary lines 3 adapts to the temperature of the environment in the ground. This temperature may be for example 14° C. This higher temperature in the secondary lines 3 is shown in dotted lines.

[0033] n FIG. 1 in the lower left secondary line 3 there is a leak 4. As water is flowing through this leak 4 even if there is no consumption in this secondary line 3 there will be a low temperature up to the leak 4 corresponding to the temperature of the water in the main line 2. From the leak 4 to the consumption side there is no flow. So, in this part of the secondary line 3 the temperature of the water corresponds after some time to the temperature of the surroundings which is 14° C.

[0034] If this secondary line 3 with the leak 4 is opened on the consumer side the water in this line 3 is flowing through a consumption meter 5 on the consumption side.

[0035] In FIG. 2 the temporal temperature curve of the water standing in or flowing through the consumption meter 5 is shown. When the flow has started the temperature in the consumption meter 5 corresponds to the temperature in the house T.sub.HOUSE. Shortly after this start at the time to the temperature of the water flowing through drops to the temperature T.sub.h which is the temperature of the water in the part of the secondary line 3 between the leak 4 and the consumption meter 5.

[0036] At a time t.sub.leak the temperature again drops to a temperature T.sub.F which corresponds to the temperature in the main line 2 and in the first part of the secondary line 3 up to the leak 4. If the flow now is stopped the temperature in the consumption meter 5 will raise again to the temperature T.sub.HOUSE.

[0037] For locating the leak the time interval between to and t.sub.leak is determined. From the consumption meter 5 it is known which volume of water has flown through the consumption meter 5 during this time interval (t.sub.0-t.sub.leak). Further, the pipe dimension, i.e. its diameter, can be pre-programmed into the consumption meter or wirelessly transferred into the meter. A typical diameter is between 50 mm and 100 mm. As the pipe dimension of this secondary line 3 is known the length of the pipe between the leak 4 and the consumption meter 5 can be calculated by dividing the volume which has flown through in the time interval t.sub.0-t.sub.leak by the cross-sectional area of the pipe. This is the basic principle of the method according to the invention.

[0038] In FIG. 3 it is shown how this method could be realized in practice:

[0039] The water for the shown water supply network comes from an utility water work 11 with a large and central pump station 12 pumping drinking water into a distribution pipeline 13 which is the main line of a water supply network. The water coming from the utility water work 11 has a temperature typically between 5° C. and 15° C. This temperature is dependent on the environment temperature and the size of the reservoir of the utility water work 11. In this example it is assumed that the temperature of the water entering the distribution pipeline 13 is 10° C. On its way through the distribution pipeline 13 the water changes its temperature depending on the temperature of the surrounding soil and the flow speed. In FIG. 3 this distribution pipeline 13 crosses an area 14 which is near by a local lake 15 with water temperature of 15° C. The temperature of the water in the lake 15 is transferred to the soil and through the soil to the water in the distribution pipeline 13 crossing this area 14. In this example the temperature of the water in the distribution pipeline 13 rises to 12° C. having crossed this area 14. This increase of temperature depends among other factors on the flow rate, the flow volume and the thermal conductivity of the wall of the pipe.

[0040] On its way through the distribution pipeline 13 the water comes to a node 16 where the main distribution pipe 13 branches into a smaller pipe 17 which is a residential pipe leading to a house 18. The temperature of the water in this smaller pipe 17 is 12° C. at the beginning. In this residential pipe 17 there is a leak 19 in the pipe. Through this leak 19 water pours out. With respect to the leak 19 there is a continuous flow through the residential pipe 17 from the node 16 to the leak 19. In flow direction behind this leak 19 there is a smaller flow of water if there is any consumption of drinking water in the house 18. There may be no flow if there is no consumption of drinking water in the house 18. As a result the water temperature in the section 20 of the residential pipe 17 rises. The section 20 is the part of the pipe from the leak 19 to the house 18. In this section 20 the temperature of the water rises to 16° C. as the water inside the pipe is heated by the surrounding soil. This temperature in the section 20 of the pipe 17 of course depends on the consumption of water in the house 18 and further of the temperature of the surrounding soil.

[0041] In the house 18 there is a consumption meter 21 which is an electronic consumption meter measuring the flow rate by means of ultrasonic technology. The consumption meter 21 does not only determine the volume flowing through the meter 21 but also the temperature of the water flowing through. For measuring the temperature there may be a temperature sensor inside the consumption meter 21 measuring the temperature of the water flowing through the consumption meter 21. Alternatively the temperature of the water flowing through the consumption meter 21 can be calculated in a water temperature determining unit by measuring the speed of sound in water when using a so-called absolute time measurement which can be implemented in the consumption meter 21.

[0042] The method for locating the leak 19 best works if a water flow to the house 18 is stopped for a while so that the water being in the section 20 of the residential pipe 17 can adapt the temperature of the surroundings. Also the water inside the consumption meter 21 adapts the temperature of the surroundings in the house 18. When a flow through the consumption meter 21 is initiated, then this flow starts with the temperature of the water T.sub.HOUSE as the water in the consumption meter 21 and the pipe leading to this consumption meter 21 inside the house 18 adapt the temperature of the house 18. The locating process starts when the flow through the consumption meter 21 starts and the temporal temperature curve as shown in FIG. 2 starts.

[0043] When the consumption meter 21 is in the leak locating modus, temperature of the water inside is analyzed. When a sharp sudden decrease is detected in the consumption meter 21, this is reported through wireless communication to a head end system. According to FIG. 2 this sudden change in temperature from T.sub.HOUSE which is 18° C. to T.sub.H which is 16° C. in this example is detected. Measurement of time and flow starts with to while water is further flowing through the pipe to the consumption meter 21. The flow rate is measured which is for example one liter per second. The temperature of the water is further watched. When the temperature of the water flowing through the consumption meter 21 drops for a second time teak the time interval from t.sub.0-t.sub.leak is determined and further the volume of flow through the consumption meter 21 during this time interval t.sub.0-t.sub.leak is determined. This second decrease in temperature from T.sub.H=16° C. to T.sub.F=12° C. happens as the water in the section 20 of the pipe which has a temperature of T.sub.H=16° C. has flown through the consumption meter 21. At the time t.sub.leak the temperature decreases again as the water from the section of the residential pipe 17 between node 16 and leak 19 arrives in the consumption meter 21. tieak and the volume flowing through the consumption meter 21 during this time interval is reported to the head end system.

[0044] After these two steep flanks at the time t.sub.0 and t.sub.leak have been detected, the location of the leak 19 is calculated either in the meter 21 or in the head end system. As this residential pipe 17 has a constant cross section the length of the section 20 can be calculated by dividing the volume which has flown through the consumption meter 21 during the time interval from t.sub.0-t.sub.leak by the cross section which is

[00001]$\pi \times \frac{D^2}{4},$

D is the diameter of the residential pipe 17. As a result, a length L is calculated which is the length L of the pipe 20 between the leak 19 and the consumption meter 21.

[0045] Often the temporal temperature curve is not as clear and simple as that of FIG. 2. The problem may be that the difference of the temperature in the residential pipe 17 before and after the leak 19 is not big enough or does not have a steep decline. This difference of temperature should be as big as possible. So it might be necessary before starting the location procedure to stop the water flow through the section 20 of the pipe 17 by installing a shutoff valve inside or next to the consumption meter 21. This shutoff valve is controlled by the control electronics of the consumption meter and the shut off may be initiated after a first acoustic leak detection when starting the leak location process. For this leak location process the valve remains closed for two or three hours which time is as long as to adapt the temperature of the water in the section 20 of the pipe to the surroundings. It is advisable to start the leak location process during the night if the flow has to be interrupted for several hours.

[0046] After this time, the valve is opened and the afore-described leak location process starts so that the sudden temperature decreases can be detected (see FIG. 2).

[0047] This acoustic leak detection is well-known and there are consumption meters which are configured to do this acoustic leak detection. Both acoustic leak detection and leak location should be initiated by external control as these methods conducted by the consumption meters need additional electrical energy which has to be provided from the battery inside the meters which is limited. For this acoustical leak detection several consumption meters 21 should typically be used.

[0048] Referring to FIG. 3 there is the consumption meter 21 in the house 18 and a further consumption meter 22 in a house 23. The house 23 with a consumption meter 22 is connected over a smaller pipe 24 which is a residential pipe 24 and which branches off from the distribution pipeline 13 at a node 25. The node 25 is as can be seen in FIG. 3 (in the direction of flow through the distribution pipeline 13) behind the node 16. Depending on the distances, an acoustic leak detection performed by the consumption meters 21 and 22 both or one of these will detect the leak 19. When evaluating the acoustic leak detection curves of the consumption meters 21 and 22 it will be clearly recognizable that the leak 19 is in the residential pipe 17 and not in the residential pipe 24. This will be recognizable from the intensity of the acoustical leak signals. When this acoustical leak detection has been finished, the consumption meter 21 is chosen for executing the leak location by analyzing the temporal temperature curve as described before with FIG. 2.

[0049] While specific embodiments of the invention have been shown and described in detail to illustrate the application of the principles of the invention, it will be understood that the invention may be embodied otherwise without departing from such principles.

LIST OF REFERENCE CHARACTERS

[0050] 1 water supply network [0051] 2 main line [0052] 3 secondary line [0053] 4 leak [0054] 5 consumption meter [0055] 11 utility water work [0056] 12 central pump station [0057] 13 main distribution pipeline [0058] 14 area [0059] 15 lake [0060] 16 node [0061] 17 smaller pipe/residential pipe [0062] 18 house [0063] 19 leak [0064] 20 section of the pipe 17 [0065] 21 consumption meter [0066] 22 consumption meter [0067] 23 house [0068] 24 smaller pipe/residential pipe [0069] 25 node [0070] Di distance between the leak 19 and the consumption meter 21 [0071] L length of the pipe 20 between the leak 19 and the consumption meter 21