The success or failure of acoustic leak detection is based greatly upon sound waves that travel through the water and through the pipe wall. In order to understand the correlation process, it is beneficial to understand the science of leak sound.
In a water distribution system, the water inside the pipe is under pressure (Typically between 50 to 100 PSI) in order to push the water to the customers.
The area outside of the pipe is not pressurized. This differential in pressure becomes apparent when a leak develops on the pipe.
The pressure inside the pipe is on a constant quest to equalize with the pressure outside of the pipe. When a leak develops, the water escapes the pipe in a violent release of energy. The friction created by this escape creates a vibration, or sound wave, that travels away from the leak in both directions. The detection of this sound wave assists the Correlator in locating leaks in underground utility systems.