MONITORING OF LEAKAGE IN WASTEWATER FORCE MAINS AND OTHER PIPES CARRYING FLUID UNDER PRESSURE

• US 20080314122A1
• Filed: 06/21/2007
• Published: 12/25/2008
• Est. Priority Date: 06/21/2007
• Status: Active Grant

• Current Assignee: Mueller International LLC (Mueller Water Products Incorporated)
• Original Assignee: National Research Council Canada
• Inventors: Wang, Alex, Hunaidi, Osama
• Granted Patent: US 7,810,378 B2
• Time in Patent Office: Days
• US Class Current: 73/40.5A
• CPC Class Codes: G01M 3/243 for pipes

Abstract

A method of detecting leakage in a force main involves placing at least two spaced sensors on the force main. Liquid is pumped through the pipe by means of a pump. The pump is shut down for an interval of time, and during the period following pump shutdown while negative pressure is present in the pipe, signals are generated at the sensors due to noise or vibration resulting from fluid being drawn into the pipe. The position of a leak in the pipe is determined by correlating the leak noise signals generated while the pipe is under negative pressure. Alternatively, the invention can be applied to a pressurized pipe, in which case conditions of negative pressure can be deliberatively created for a period to draw in fluid from the outside.

Claims

1. A method of detecting leakage in a pipe for carrying a pressurized fluid, comprising:

creating conditions of negative pressure in said pipe so that external fluid is drawn into said pipe to generate noise or vibration at a leak location;

generating signals corresponding to said noise or vibration from spaced sensors located on said pipe; and

analyzing said signals to determine the location of said leak.

2. A method as claimed in claim 1, wherein said negative pressure is induced by shutting off a pump forcing said pressurized fluid through said pipe, said negative pressure arising in a period following pump shutdown.

3. A method as claimed in claim 1, wherein said negative pressure is induced by isolating a section of said pipe and withdrawing fluid from within the pipe.

4. A method as claimed in claim 1, wherein said pipe is at least partially immersed in water, and said fluid is said water.

5. A method as claimed in claim 4, wherein said pipe is a submarine pipe extending across a river or body of water.

6. A method as claimed in claim 1, wherein said fluid is air.

7. A method as claimed claim 1, wherein said signals are analyzed by cross correlation techniques.

8. A method as claimed in claim 1, wherein said sensors are hydrophones.

9. A method as claimed in claim 1, wherein said sensors are vibration sensors.

10. A method as claimed in a claim 2, wherein the liquid in the pipe is wastewater.

11. A method as claimed in claim 2, wherein the pump is periodically run and shutdown to permit leak detection during periods of pump shutdown.

12. A system for detecting leakage in a pipe carrying pressurized fluid, comprising:

at least two spaced sensors located on the pipe;

means for periodically creating negative pressure in the pipe to draw fluid into the pipe from ambient at the location of a leak; and

a computer programmed to determine the location of the leak by analyzing signals representing noise or vibration occurring at the location of said leak.

13. A system as claimed in claim 12, wherein the fluid is forced through the pipe by a pump, and the arrangement for creating negative pressure includes a switch for periodically shutting down the pump for an interval during which negative pressure develops.

14. A system as claimed in claim 13, wherein the pipe is a wastewater force mains.

15. A system as claimed in claim 14, wherein said pipe is at least partially immersed in water, and said fluid is said water.

16. A system as claimed in claim 12, wherein said pipe is a submarine pipe extending across a river or body of water.

17. A system as claimed in claim 12, wherein the pipe is exposed at the location of the leak, and said fluid is air.

18. A system as claimed in claim 12, wherein the pipe is a pressurized water distribution pipe.

19. A system as claimed in claim 18, wherein the arrangement for creating negative pressure in the pipe includes valves for isolating a section of the pipe, and a pump for withdrawing fluid from within the pipe.

20. A system as claimed claim 12, wherein said computer is programmed to analyze said signals by cross correlation techniques.

21. A system as claimed in claim 12, wherein said sensors are hydrophones.

22. A system as claimed claims 21, wherein said sensors are vibration sensors.

23. A system as claimed in claim 12, comprising a controller for periodically running the pump and shutting down the pump to permit leak detection during periods of pump shutdown.

24. A method of detecting leakage in a wastewater force mains, comprising:

periodically pumping wastewater through the force mains by means of a pump;

during a period following pump shutdown while conditions of negative pressure are present in the mains, detecting noise or vibration at a leak location due to fluid being drawn into said mains with spaced sensors located on said mains; and

analyzing signals from said spaced sensors corresponding to said noise or vibration to determine the location of said leak.

25. A method as claimed in claim 24, wherein said signals are analyzed by cross correlation techniques.