Datasheet | April 11, 2011

Datasheet: Trunk Main Leak Detection

Source: Mueller Water Products
trunkmain_mar4_2011_update

Virtually every water utility has at some point experienced a catastrophic failure of a large-diameter trunk main, resulting in damage to both the water main itself and the surrounding infrastructure.

In the past, leak-noise correlators have been ineffective in locating leaks in large-diameter trunk mains. Current detection methods involve a microphone being placed inside a pipe and being borne downstream by the flow of water. The leak is identified when the microphone passes by its location. While this technology is effective, it has drawbacks that limit its use. As a result, few utilities have done any leak detection on their trunk mains.

Echologics has now succeeded in making leak-noise correlation technology effective on large-diameter trunk mains, as evidenced by extensive field-testing.

How it Works
A correlator listens passively for noise created by a leak. Two sensors are mounted on existing pipeline appurtenances so that the leak lies between them, or is "bracketed" by the sensors. A leak that lies outside the area spanned by these sensors is known as an "out-of-bracket" leak. Since correlation is a time-of-flight technology, the leak's location is determined by the length of time it takes for its sound to arrive at each sensor.

Typically for trunk mains, hydrophone (water microphone) sensors are mounted on the pipe at existing appurtenances such as air valves or fire hydrants. The distance between the two sensors can range from 1000' (300m) up to over 5000' (1300m).

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