Acoustic leak detector

• US 4,327,576 A
• Filed: 05/05/1980
• Issued: 05/04/1982
• Est. Priority Date: 05/05/1980
• Status: Expired due to Term

• Current Assignee: the united states of america as represented by the secretary of the navy
• Original Assignee: the united states of america as represented by the secretary of the navy
• Inventors: Moore, Paul M., Powell, Lloyd E., Dickey, Joseph W.
• Primary Examiner(s): MYRACLE, JERRY
• Application Number:
  US06/146,984
• Time in Patent Office: 729 Days
• Field of Search: 73/40.5 A, 73/40.5 R, 73/659
• US Class Current: 73/40.50A
• CPC Class Codes: G01M 3/243 for pipes

Abstract

The invention relates to a leak detecting device for pipe systems having electronic channels for processing the acoustical signals from the source of the leak to determine the direction of propagation of the leak signal. Each channel includes a transducer, an amplifier unit, a variable delay unit for delaying the transmission of signals received from the amplifier unit, and a multiple-averager unit which respectively multiplies and then averages input signals from the variable delay unit of the same channel and, depending on the mode of operation, from the amplifier unit of either the same or the other channel. Operating in a first mode to determine the frequency and wavelength of the primary leak signal, the signals from the variable delay unit of one channel are combined with the signals from the amplifier unit of the same channel in the multiplier-averager unit. Upon determining the wavelength of the primary leak signal, the transducers are spaced apart by about one-quarter of such wavelength and attached to the pipe. Operating then in a second mode to determine the direction of propagation of the acoustical leak signal, the multiplier-averager unit of one channel receives signals from the variable delay unit of the same channel and the amplifier unit of the other channel.

Claims

1. A leak detecting and locating device for a fluid system having a leaking component within the system comprising:

first and second processing channels adapted to be attached to a fluid system for converting acoustical signals from a leaking component into electrical signals;

means for combining the electrical signals from said channels for determining the direction of the leaking component in the fluid system with respect to said first and second channels; and

means receiving the combined signals for indicating the direction of the leaking component with respect to the detecting device, wherein each of said channels includes, a transducer mounted to receive, within a preselected frequency range, the characteristic dominant primary acoustical signals from the leaking component and to convert the acoustical signals to primary electrical signals;

an amplifier unit for increasing the strength of the signal from the transducer;

a variable delay unit for delaying the transmission of signals from said amplifier unit; and

a means for processing the signals from said variable delay unit with the signal from the amplifier unit of one of said channels.

2. The device according to claim 1, further comprising:

a switch means for interconnecting said first and second channels and positionable in either a first or second modal position, when said switch means is positioned in said first modal position the signals from said amplifier unit of one channel are combined in the processing means of said same channel with the signals from said variable delay unit of said same channel, and when said switch means is moved to said second modal position the signals from said amplifier unit of each channel are combined in the processing means of the other channel with the signals from said variable delay unit of the other channel.

3. The device according to claim 2, further comprising:

a summing and rectifing means operable when said switch means is positioned in said first modal position and connected to said processing means of said one channel for displaying the average absolute magnitude of said signal from said processing means.

4. The device according to claim 2, further comprising a difference means operable when said switch means is positioned in said second modal position and connected to said processing means of each channel for subtracting the average magnitude of the signals from said processing means of said second channel from the average magnitude of the signals from said processing means of said first channel.

5. The device according to claim 1, further comprising means connected to said amplifier units of each channel for determining the relative magnitude of the signals in said amplifier units and means in each amplifier unit for adjusting the amplification magnitude of the signals processed therein.

6. The device according to claim 1, further comprising means connected to one of said amplifier units for detecting and displaying the magnitude of the amplified signal in said amplifier unit.

7. A method of determining the direction of propagation of acoustical leak signals in a pipe system utilizing two transducers spaced apart a predetermined distance comprising the steps of:

receiving the acoustical signal from a common source by each transducer;

equalizing the signals from the transducers by separate amplification;

delaying each of said signals by a predetermined amount;

comparing the phase of the equalized signals from one transducer with the delayed signal from the other transducer; and

displaying the resultant signal to indicate the direction to the source of said acoustical leak signal.

8. A method of determining the period of a predominant, primary acoustical signal caused by a leak in a fluid system comprising the steps of:

receiving an acoustical leak signal;

selecting from the received acoustical signals a predominant, primary leak signal;

varyiably delaying the primary leak signal with respect to itself; and

processing said primary leak signal and said delayed primary leak signal to identify a 90°

phase difference between said signals whereby a minimum absolute value output is produced.

9. A leak detecting and locating device for a fluid system having a leaking component within the system comprising:

first and second processing channels adapted to be attached to a fluid system for converting acoustical signals from a leaking component into electrical signals;

means for combining the electrical signals from said channels for determining the direction of the leaking component in the fluid system with respect to said first and second channels;

means receiving the combined signals for indicating the direction of the leaking component with respect to the detecting device, wherein said first and second channels include transducers attached to a pipe, in a spaced apart arrangement; and

sound absorbing means spaced along the pipe adjacent the transducer arrangement for absorbing and attenuating the acoustical noise transmitted through the pipe to the transducers.

10. A leak detecting and locating device for a fluid system having a leaking component within the system comprising:

first and second processing channels adapted to be attached to a fluid system for converting acoustical signals from a leaking component into electrical signals;

means for combining the electrical signals from said channels for determining the direction of the leaking component in the fluid system with respect to said first and second channels; and

means receiving the combined signals for indicating the direction of the leaking component with respect to the detecting device, wherein each of said channels includes;

a transducer mounted to receive the predominant, primary acoustic signals from the leaking component and to convert the acoustic signals to electrical signals;

means for equalizing the signal from one of said transducers with the signals from said transducer of the other channel;

means for delaying the signals from said equalization means a predetermined amount; and

means for comparing the phase relationship of the delayed signal from the delay means of the same channel with the equalized signal from the delay means of the other channel.

11. A leak detecting and locating device for a fluid system having a leading component within the system comprising:

first and second processing channels adapted to be attached to a fluid system for converting acoustical signals from a leaking component into electrical signals;

means for combining the electrical signals from said channels for determining the direction of the leaking component in the fluid system with respect to said first and second channels; and

means receiving the combined signals for indicating the direction of the leaking component with respect to the detecting device, wherein each of said channels includes, a transducer mounted to receive, within a preselected frequency range, the characteristic dominant primary acoustical signals from the leaking component and to convert the acoustical signals to primary electrical signals;

an amplifier unit for increasing the strength of the signal from the transducer;

a variable delay unit for delaying the transmission of signals from said amplifier unit; and

a means for processing the signals from said variable delay unit with the signal from the amplifier unit of one of said channels, wherein in one mode of operation the amplified signal is fed from the amplifier unit in the same channel as the channel containing the variable delay unit.

12. A leak detecting and locating device for a fluid system having a leaking component within the system comprising:

first and second processing channels adapted to be attached to a fluid system for converting acoustical signals from a leaking component into electrical signals;

means for combining the electrical signals from said channels for determining the direction of the leaking component in the fluid system with respect to said first and second channels; and

means receiving the combined signals for indicating the direction of the leaking component with respect to the detecting device, wherein each of said channels includes, a transducer mounted to receive, within a preselected frequency range, the characteristic dominant primary acoustical signals from the leaking component and to convert the acoustical signals to primary electrical signals;

an amplifier unit for increasing the strength of the signal from the transducer;

a variable delay unit for delaying the transmission of signals from said amplifier unit; and

a means for processing the signals from said variable delay unit with the signal from the amplifier unit of one of said channels, wherein in one mode of operation the amplified signal is fed from the amplifier unit in a different channel than the channel containing the variable delay unit.