PC multimedia-based leak detection system for water transmission and distribution pipes
First Claim
1. A method of detecting leaks in pipes comprising the steps of:
- listening to a leak in a fluid pipe from a first location and from a second location simultaneously to provide first and second signals respectively, the first and second location separated by a known distance of pipe; and
, calculating an impulse response over a finite range of frequencies based on the first and second signals and using the channel having a lower amplitude as the reference signal to determine a leak location within the pipe, the leak location a distance from the first location.
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Accused Products
Abstract
This invention pertains to the detection of leaks in plastic water distribution pipes by processing the sound or vibration induced in the pipe by water escaping under pressure. Acoustic leak signals are measured at two (or more) contact points with the pipe, e.g., fire hydrants or valves, using vibration sensors or hydrophones. The signals are digitally recorded using the computer'"'"'s soundcard. The leak is located using the difference in arrival times of two leak signals as determined from the cross-correlation function traditionally used in leak detection applications or an enhanced impulse response function. The enhanced impulse response function eliminates the need to filter leak signals before processing and hence avoids the uncertainty involved in selecting filter cutoff frequencies for non-experts. Listening to leak sound in plastic pipes is made possible in software by shifting their low-frequency content to an audible higher range. The software implementation of this system can be readily integrated with commercially available RF-based data transmitters and leak sensors—thus providing a complete, flexible, and inexpensive leak detection system.
141 Citations
25 Claims
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1. A method of detecting leaks in pipes comprising the steps of:
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listening to a leak in a fluid pipe from a first location and from a second location simultaneously to provide first and second signals respectively, the first and second location separated by a known distance of pipe; and
,calculating an impulse response over a finite range of frequencies based on the first and second signals and using the channel having a lower amplitude as the reference signal to determine a leak location within the pipe, the leak location a distance from the first location. - View Dependent Claims (2, 3, 4)
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5. A method of detecting leaks in pipes comprising the steps of:
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listening to a leak in a fluid pipe from a first location and from a second location simultaneously to provide first and second signals respectively using a first and a second acoustic sensor coupled to a sound circuit within a personal computer, the first and second location separated by a known distance of pipe; and
,calculating a leak location within the pipe absent a step of filtering the signals to reduce a noise content of the signals. - View Dependent Claims (6, 7, 8, 9, 10, 11)
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12. A method for determining the location of a leak in a pipe comprising the steps of:
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providing first and second sensor means operably connected to said conduit for generating signals related to sensing vibrations of said conduit;
recording said signals as a function of time;
determining the time difference between arrival of vibrations which generate signals at said first sensor means and said second sensor means, respectively, by subjecting a plurality of multiple point consecutive time records for each signal to fast Fourier transform analysis of the time domain data to produce auto spectra values of said first sensor signal, Gaa, and said second sensor signal, Grr, respectively;
calculating the cross spectra values, Gar, of the respective series of time records of said first and second signals, respectively;
summing the auto spectra values and the cross spectra values and determining averages of each, respectively;
calculating the impulse response over a finite range by determining the inverse Fourier transform of the ratio of the averaged cross spectra to the averaged auto spectra of at least one of said auto spectra over a finite range;
determining a peak value of such resultant values from time=0 to determine said time difference; and
determining the location of said event based on said time difference and the acoustic velocity of a stress wave in the pipe. - View Dependent Claims (13, 14, 15, 16)
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17. A method of detecting leaks in pipes comprising the steps of:
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listening to a leak in a fluid pipe using an acoustic sensor to form leak signals from a first location and from a second location simultaneously to provide first and second signals respectively, the first and second location separated by a known distance of pipe;
digitising the leak signals using a sound circuit within a personal computer, sound circuit introducing significant noise into the signals; and
,calculating a leak location within the pipe using a method of calculation that reduces effects of the noise introduced by the sound circuit and absent a step of filtering the leak signals. - View Dependent Claims (18, 19, 20, 21, 22, 23, 24)
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25. A method of detecting leaks in pipes comprising the steps of:
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listening to a leak in a fluid pipe using an acoustic sensor to form a leak signal from a first location to provide a first signal, digitising at a first sampling rate the leak signal using a sound circuit; and
,playing the leak signal at a second different sampling rate than the rate at which it was digitised in order to shift sounds at inaudible frequencies to frequencies at which they are audible.
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Specification