JP2000310399A - Detection of leakage of pipe - Google Patents

Abstract

PROBLEM TO BE SOLVED: To shorten inspection time without inspecting the whole of an area doubtful of water leakage. SOLUTION: This device permanently or semi-permanently installed on water pipes 15, 16 underground to detect leakage inside has a hydrophone 26 to be installed to acoustically monitor water flowing along the pipes 15, 16 and a means (printed circuit board 29) to analyze a parameter of an output signal of the hydrophone 26 and to transmit an alarm signal when the parameter exceeds a certain maximum value or is lower than a certain minimum value. This device also has a radio transmitter to show detection of leakage by transmitting the alarm signal to a remote receiver. The maximum and minimum values are favourably computed by using data with the lapse of time provided from the hydrophone 26 so that the values are automatically adjusted so as to suit to a place of the device.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technique for detecting a leak in a pipe carrying a fluid such as water.

[0002]

BACKGROUND OF THE INVENTION It is known to know the location of a leak in an underground water pipe using a so-called leak detector that can accurately locate the location of the leak before excavating the underground.

Before using a leak detector, it is common practice to first determine the general geography of the area where the water is leaking. Usually, the presence of a leak is manifested by first reading the instruments located at the various distribution points of the water to see, for example, whether nighttime consumption has increased. Next, the location of the suspected leak is located using the leak detector.

[0004]

A disadvantage of this method is that it uses a leak locating device to investigate the entire area where the fluid is suspected to be leaking, and this is time consuming.

The present invention has been made in view of the above-mentioned problems, and has as its object to provide a pipe leak detecting device which can reduce such problems.

[0006]

According to the present invention, in a device for detecting tube leaks, a transducer for acoustically monitoring the tube, analyzing one parameter of the output signal of the transducer, An apparatus is provided having means for generating an alarm signal when a parameter is above a certain maximum value or below a certain minimum value, and means for outputting the alarm signal.

In use, multiple devices according to the present invention can be temporarily or permanently installed in a pipe at various locations in a geographical supply area. Once a leak is located in an area, monitoring the alarm signal with a remote receiver makes it relatively easy to more accurately know where to look in the area.
Thus, it will be appreciated that there is no need to survey the entire area.

In one embodiment, the alarm signal output means includes a transmitter such as a wireless transmitter for transmitting a wireless alarm signal to a remote receiver.

[0009] The remote receiver may include means for recording the location where the alarm signal was received. Thus, for example, a receiver can be attached to a delivery vehicle that frequently visits each area. In that case, data is sent out regularly from the receiver, and if an alarm signal is recorded, the exact location will be sent out with the data. Preferably, the position recording means is configured to receive a signal from a satellite whose position can be confirmed on a global scale.

In the second embodiment, the alarm signal output means may be configured to transmit an alarm signal to a remote receiver along a cable. In the third embodiment, the alarm signal output means may include a light or audible sound transducer.

[0011] Preferably, the transmitting means transmits a low-power radio signal, thereby conserving the battery power of the device and enabling multiple devices to transmit at the same frequency without risk of interference.

In use, the alarm signal is detected by patroling the geographic area with a remote receiver device until the alarm signal is detected. This allows the location of the leak to be accurately located using a conventional leak detector.

Preferably, the transmitter is configured to transmit a different standby signal when the parameter is equal to or less than the maximum value or equal to or greater than the minimum value. This makes it clear that if the remote receiver detects neither a standby signal nor an alarm signal, the device will not be operating properly.

[0014] Preferably, the transmitter only transmits signals periodically to further conserve battery power.

[0015] Preferably, the alert signal is transmitted more frequently than the standby signal so that the alert signal is not overlooked while traversing the area.

The most common method of locating a leak uses the principle of correlation where two acoustic transducers are mounted at different points on the tube being analyzed.
In that case, the correlator compares the noise detected at the two sensor points and determines the difference between the time required for the noise to reach one sensor and the time required for the noise to reach the other sensor. The position of the leak is obtained from the following equation, where L is the position of the leak, D is the distance between the sensors, V is the speed of sound passing through the tube to be inspected, and Td is the time delay between noise signals.

L = [D− (Vx Td)] / 2

Each time a measurement is taken, it is difficult and time consuming to install the acoustic transducer of the leak locating device in the tube, and the transducer is repositioned until the leak is accurately located and some new measurements are made. It will be appreciated that it may be necessary to do so.

Therefore, the device preferably has a port for making an external connection to the acoustic transducer. In use, if an alarm signal is detected by one of the devices, the leak can be accurately located by connecting a correlator to the respective ports of the two leak detection devices according to the present invention. The correlator performs the measurement using two devices of acoustic transducers. That is, it is much easier and faster to take measurements because it does not need to spend the time connecting individual acoustic transducers to the tube.

Preferably, the port has a transmitter which can communicate wirelessly with the corresponding port of the leak locating device. In this way, it is possible to dispose a completely closed hollow cylindrical body in the apparatus and prevent intrusion of fluid.

[0021] Leaks in the tube generate noise, so any leaks can be detected. The problem with detecting leaks in this manner, however, is that noise generated by normal fluid consumption can mask noise generated by leaks. Therefore, the apparatus preferably has a clock and is arranged with analysis means for analyzing the parameters of the output signal of the transducer during the night when little or no fluid is normally consumed.

All tubes have different noise characteristics. Thus, the level of noise indicating a leak can vary greatly within the same geographic area. This problem is exacerbated by the fact that plastic tubes do not transmit as much as metal tubes.

Therefore, simply comparing the values of the parameters at the output of the transducer using the same maximum and / or minimum value at each location, it is not possible to reliably detect leaks at different locations.

In order to overcome this problem, the analyzing means is arranged to periodically measure the output level of the transducer to determine the average of the previous measured level, and the monitoring means further comprises: And / or preferably configured to determine a minimum value. In this way, the level at which a warning signal is issued at each location will depend on the average value of the previous noise at that location.

Preferably, the alarm signal is also generated when the parameter is above the absolute maximum or below the absolute minimum.

A drawback of using the average value to determine the maximum or minimum value is that the measurements used to calculate the average value may include measurements that indicate leaks, in which case In addition, some of the leaks may not be detected. In order to prevent such a situation, it is preferable that the monitoring unit is configured to exclude a measured value equal to or larger than the maximum threshold or equal to or smaller than the minimum threshold from the calculation of the average value.

The maximum and / or minimum thresholds should be different from place to place to take into account different environments. Accordingly, the monitoring means is preferably arranged to exclude from the calculation of the average the measured values which are larger or smaller by a predetermined amount than the median of the stored measured values.

In order to prevent intermittent noises from generating an alarm, the monitoring means may be adapted to determine if the measured values above said maximum or below said minimum are not significantly different from the temporally adjacent measurements. Preferably, it is only configured to generate an alarm signal.

The monitoring means performs a series of measurements of the output level of the transducer, compares the level exceeding a predetermined percentage of the number of measurements to the maximum or minimum value, and / or determines the predetermined number of measurements. Preferably, it is configured to compare the spread between levels beyond a given percentage number.

Known acoustic transducers can be mounted inside a hollow tube that is screwed to a fitting in a tube. However, a disadvantage of this arrangement is that air must be vented from the hollow cylinder, so that the acoustic transducer is in complete contact with the fluid in the tube.

[0031] Air is carried along with the fluid flowing along the tube, which air can collect in closed cavities in the tube. As a result, failure to regularly vent air from the cavity in which the transducer is mounted may prevent the leak detection device according to the present invention from operating properly.

In one embodiment, an air release valve is mounted in a flow path passing through the hollow cylindrical body of the device, and a sensing means for opening the valve when the accumulation of air in the flow path is detected. Will be arranged.

Alternatively, in accordance with the present invention, there is provided, as is apparent from the second aspect, an assembly having a transducer for acoustically monitoring fluid flowing along a tube, the assembly comprising a transducer on the wall of the tube. A hollow cylindrical body having a port for connecting to a corresponding port therein, a fluid flow path extending through the hollow cylindrical body, an acoustic transducer mounted inside the flow path, and the flow path. Flow diverting means for deflecting at least a portion of the fluid flowing along the tube therethrough.

[0034] In use, the assembly is branch attached to a conventional port in a tube, and at least a portion of the fluid in the tube is diverted through the passage. Therefore, the hollow cylinder will always be flushed with fluid and no air will accumulate around the transducer. In addition, the fluid
The air present in the hollow cylinder when the device is first installed is also washed away.

Preferably, the flow diverting means is configured to divert any fluid flowing through the passage along the tube to be analyzed.

[0036]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the accompanying drawings which are merely examples.

Referring to FIG. 1, this is connected to the hollow cylindrical body of a conventional stopcock (stopper) 12 of the type normally arranged in many underground pits outside the house by turning an adapter 11 around. Leak detection apparatu
s) 10 is shown. However, it will be appreciated that the device can be connected to any convenient point that has access to the water in the tube.

The stopcock 12 is usually provided with an inlet pipe (water pipe) 15 and an outlet pipe (water pipe) connected to respective ports.
A valve is provided that can be closed to stop the flow of water through the opening 13 in the partition wall 14 located between the partition wall 14. However, a leak detector 10
In order to attach the adapter, the screw must be loosened to remove the valve member from the hollow cylindrical body of the stop cock 12, and the adapter 11 must be attached to a predetermined position. Next, as shown, the base 25 of the leak detector 10 is screwed to the upper end of the adapter 11.

The adapter 11 has a tubular extension 17,
This portion seals the periphery of the opening 13 of the partition wall 14. This tubular extension has a through passage 18 extending the full length of the adapter 11 and is in communication with a corresponding tubular passage formed in the base 25 of the leak detector 10. It is also possible to arrange a valve member (not shown) to close the through passage 18 so that the function of the stopcock is left.

The adapter 11 further has an annular cross-section passage 21 extending concentrically with the central passage 18 therethrough. The lower end of the passage 21 is the partition wall 1 of the stopcock 12.
4 communicates with a chamber 22 formed above.

The chamber 22 above the partition wall 14
The corresponding chamber 13 below the partition 14 communicates with the inlet pipe 15 and communicates with the outlet pipe 16.

The upper end of the annular section passage 19 through the adapter 11 communicates with the corresponding annular section passage 21 of the base 25 of the leak detector 10.

The central passage 19 in the base 25 of the leak detector 10
An elongated hydrophone 26 is disposed therein. The hydrophone 26 is supported by a web (not shown) extending in a radial direction. Base 25 of leak detector 10
The upper end of the central passage 19 communicates with the upper end of an outer passage (annular section) adjacent to the bottom 27 of the hollow cylindrical body 28 of the detector.

A printed circuit board 29 is provided in the hollow cylindrical body 28 of the leak detector 10 in a sealed manner, and is provided with a wire.
Extends from the hydrophone 26 toward the printed circuit board 29. A window 30 is provided at the upper end of the hollow cylindrical body 28 of the leak detector 10, and an infrared transceiver 31 is provided below the window 30. The infrared transceiver 31 is connected to a printed circuit board 29 by electric wires. A battery (not shown) is also mounted in the hollow cylindrical body 28 of the leak detector 10.

At the time of use, if the leak detector 10 and the adapter 11 are attached to the stop cock 12 as described below, water can flow through the inlet pipe 15. Water is supplied from the inlet pipe 15 to the upper chamber 2 of the stopcock 12.
After flowing into the inside 2, it flows upward through the outer annular passages 21 and 24 in the adapter 11 and the leak detector 10, and passes through the hydrophone 26. Finally, the water flows into the lower chamber 23 of the stopcock 12 and into the outlet tube 16.

As for the entire flow of water, the adapter 11
It will be understood that the divergence passes through the leak detector 10 and further through the hydrophone 26 mounted axially in the passage 19. Therefore, in use, it is unlikely that air will accumulate around the hydrophone 26 and interfere with the function of the leak detector 10. Also, any air present in the leak detector 10 when it was first installed will be washed away by the flow of water. Thus, it will be appreciated that there is no need for venting air from the detector, and the effect is that the detector, once installed, requires no further maintenance.

If a leak occurs in the tube, noise is created as the water passes through the leak. During the day, it is difficult to detect the noise generated by the leak, since normal water consumption also generates large noise. However, the detector 10 is configured to acoustically monitor the tube even during nighttime when water consumption is typically very low.

At night, the noise level increased by leakage
It is possible to detect and issue an alarm. There is also a leak
The detected sound level remains almost constant.
However, if there are no leaks, the noise level will vary greatly.
Move. Therefore, the detector 10 can be
Periodic noise samples over a predetermined period
It is constituted so that it may be collected periodically. Recorded next
The data shows the percentage of measured values at different levels.
A noise level distribution histogram is formed.
The results obtained depend on the level and spread parameters.
Are shown. Where level = Ln₁, Spread = Ln
₂-Ln₃It is. Ln _xValue exceeds n% of the time
Indicates the noise level.

First, on the first day of installation, a leak is detected by comparing the two parameters of the measured values to their respective absolute values X and Y, which are pre-programmed into the detector 10. These parameters are as described above, which is spread between the excess noise level between the n% of the excess noise levels and n ₂ and n _3% of the measuring time period. Therefore, level (Ln ₁ )> Xd
B, or spread (Ln ₂ -Ln ₃₎ <leaking when YdB is shown.

In the next six days, a leak is detected by comparing these two parameters with the absolute values X and Y and the two parameters of the measurements taken on the first day.
In the latter case, a leak is indicated if the parameters of the day differ from the corresponding measurements on the first day by a predetermined amount or more.

After 7 days, assuming that no leak has been detected, a standard reference value is calculated which can be compared to the two parameters. Initially, for both parameters, the median for 7 days with no leaks is determined and the other six values are compared to this median.

If the magnitude of the difference between any of these six values and the median is greater than a predetermined amount, that value is excluded from the reference calculation. Therefore,
| Second level−median level |> (GdB),
Second level values are excluded. If | second spread−median value of spread |> (HdB), the second spread value is excluded. A standard reference value for the two parameters is then formed from the average of the values that were not to be excluded from the reference calculation.

From then on, every day, the daily values of the subsequent level and spread are compared with the absolute values "X", "Y" and the "determined standard reference value". Therefore "new level">
(XdB), or “new spread” <(YdB), or “new level” − “standard level value”> (Qd
B) or “reference spread value” − “new spread”>
(RdB) would indicate a leak.

At each location where the device is located, the measurements are compared to absolute values as well as reference values calculated using leak-free measurements taken at that location during the first few days after installation. Therefore, the leak is reliably detected with high reliability.

It is also possible to use the system intermittently at night and generate noise by spurious leaks. If a leak is detected in that case, the device takes another set of measurements on the same day to determine where the leak is indicated. Thus, an alarm condition will occur only if a set of two or more consecutive measurements indicates a leak. It is clear that this number can be increased in areas where water is used intermittently at night.

When an alarm condition occurs, the power of the low-power radio transmitter housed in the hollow cylindrical body 18 of the apparatus is turned on, and the alarm signal is periodically transmitted. If there are no leak conditions, the transmitter can also periodically send a standby signal to indicate that the device is functioning properly. In order to conserve battery power, the time division ratio of the standby signal is preferably larger than the time division ratio of the alarm signal.

The present invention includes the installation of a plurality of leak detection devices according to the present invention at different locations in one geographical area. Thus, if a leak is detected in that area, it is relatively easy for the wireless receiver to patroll through the area and detect the alarm signal. It will be apparent that a leak has occurred adjacent to the site of the device transmitting the signal. Thus, the use of a leak detection device having two remote data acquisition devices interconnected via wires or wireless communication circuits allows the location of the leak to be quickly and easily located.

Each device has an optical coupler 50 as shown in FIG. In use, the coupler 5 of the two data recording devices
The zeros are connected to respective leak detection devices of the present invention located on either side of the potential leak location. The upper end of the hollow cylindrical body 28 of each device extends into a correspondingly shaped socket 51 in the coupler 50.

An infrared transceiver 52 located at the upper end of the socket 51 in the coupler 50 communicates with the transceiver 31 in the leak detector 10. Therefore, the two recording devices
It will be possible to communicate directly with the hydrophone 26 in each connected leak detection device.

The noise generated by the leak is detected by each hydrophone 26, but the time it takes for the noise to reach these two hydrophones is different.
Thus, the location of the leak can be determined as a function of this time difference.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing one embodiment of a leak detection device according to the present invention, which is connected to a water pipe.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Leak detection apparatus (leak detector) 11 Adapter 12 Stopcock 13 Opening 14 Partition wall 15 Inlet pipe (water pipe) 16 Outlet pipe (water pipe) 17 Extension part of adapter 18 Penetration path (central passage) 19 Passage 21 Passage 22 Chamber 23 chamber 24 passage 25 base of leak detector 26 hydrophone 27 bottom of hollow cylinder in leak detector 28 hollow cylinder of leak detector 29 printed circuit board 30 window of hollow cylinder 31 infrared transceiver 50 Optical Coupler 51 Socket 52 Infrared Transmitter / Receiver

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 3J071 AA12 CC11 DD30 EE06 EE07 EE11 EE38 FF12

Claims (20)

[Claims] 1. A method for detecting tube leaks, comprising:
A transducer for acoustically monitoring the tube, and analyzing a parameter of the output signal of the transducer to generate an alarm signal when the parameter exceeds a certain maximum value or falls below a certain minimum value. And means for outputting the alarm signal. 2. The apparatus of claim 1 wherein said alarm signal output means comprises an optical or audible sound transducer. 3. The apparatus according to claim 1, wherein said alarm signal output means transmits an alarm signal to a remote receiver along a cable. 4. The apparatus according to claim 1, wherein said alarm signal output means transmits a wireless alarm signal to a remote receiver.
The described device. 5. The apparatus of claim 1, wherein said transmitter transmits a low power radio signal. 6. The apparatus according to claim 4, wherein said transmitter transmits a standby signal when said parameter does not exceed said maximum value and / or does not fall below said minimum value. . 7. The apparatus according to claim 4, wherein said transmitter transmits a signal periodically. 8. The apparatus according to claim 6, wherein said transmitter transmits signals periodically, and said alarm signal is transmitted more frequently than a standby signal. 9. The apparatus according to claim 1, wherein said apparatus has a port for making an external connection of an acoustic transducer. 10. The apparatus of claim 9 wherein said port comprises a transmitter in wireless communication with a corresponding port of the leak locator. 11. The apparatus according to claim 1, wherein said apparatus has a clock and is provided with analysis means for analyzing the parameters of the output signal of the transducer at night.
An apparatus according to any of the preceding claims. 12. The analyzing means according to claim 1, wherein said analyzing means periodically measures an output level of said transducer and obtains an average of previously measured levels.
The apparatus according to claim 1, further comprising determining the maximum and / or minimum value from the average. 13. The apparatus of claim 12, wherein the alarm signal is also generated when the parameter is above a certain absolute maximum and / or below a certain absolute minimum. 14. The apparatus according to claim 12, wherein said monitoring means is configured to exclude a measured value above a maximum threshold value or below a minimum threshold value from calculation of said average. 15. The apparatus according to claim 12, wherein said monitor means excludes a measured value larger or smaller than a median value of the stored measured values from the calculation of said average by a predetermined amount. The apparatus according to any one of claims 14 to 14. 16. The monitoring means according to claim 1, wherein said monitoring means generates an alarm signal only when a measured value exceeding said maximum limit and / or a measured value below said minimum limit is not significantly different from a measured value adjacent thereto. An apparatus according to any one of claims 12 to 14. 17. The monitor means for taking a series of measurements of the output level of the transducer and comparing a level exceeding a predetermined percentage of the measurements to the maximum or minimum value and / or measuring the output level. A configuration for comparing the spread between levels above a predetermined upper and lower percentage number of values.
16. The apparatus according to any one of 16. 18. A port for connecting to a corresponding port on the wall of the tube, a fluid passage extending through the hollow cylinder and having an opposite end communicating with the port, 18. The device according to any of the preceding claims, wherein the device comprises an acoustic transducer mounted inside and flow diversion means for diverting at least a portion of the fluid flowing along a tube through the flow path. apparatus. 19. An assembly having a transducer for acoustically monitoring fluid flowing along a tube, a port for connecting to a corresponding port on a wall of the tube.
A fluid flow path having an opposite end extending through the hollow cylinder and communicating with the port, an acoustic transducer mounted inside the flow path, and at least a fluid flowing along a tube passing through the flow path; An assembly having flow diverting means for diverting a portion. 20. The assembly according to claim 19, wherein said flow diverting means diverts all of the fluid flowing along the tube to be analyzed through said passage.