Acoustic Sensor Technologies for Leak Detection
The majority of the water distribution systems at Department of Defense (DoD) installations were installed before 1970 and are reaching the end of their design lifetime. This aging underground piping infrastructure suffers from numerous potable water leaks. In most cases, a leak is not addressed or even located until water has risen to the surface, which can take months or even years to occur. Studies performed by the EPA have indicated that on average 14% of a system’s use is consumed by leaks, but in some systems this value can be as high as 60%.
Acoustic technology can detect these losses before there is any physical evidence of a leak, which has the potential to save thousands of gallons of water per day for a single leak. The challenge is that DoD installations have a variety of piping materials, sizes, and configurations as result of the systems being expanded over the years. The objective of ESTCP project EW-201339: “Innovative Acoustic Sensor Technologies for Leak Detection in Challenging Pipe Types” is to validate the performance of these systems, and to determine their suitability for deployment.
This project uses innovative acoustic leak detection sensors combined with location correlation software. Acoustic sensors can detect the sound of water rushing through a leak in a pipeline. The cross correlation components use two different sensors to locate a leak: the time difference between when the two signals are received determines the location of the leak.
The project team created a dedicated test bed to evaluate two types of systems and three different products. The first type of system is intended for permanent installation on a pipeline, and continuously monitors for leaks. Typically, a scan is performed in the middle of the night when building water usage is anticipated to be at its lowest point. The Gutermann Zonescan Technology uses up to 100 permanently installed sensors to probe the system for leaks on a continuous basis. This system can be connected to existing meter reading or building automation systems.
The second type of system is intended for intermittent inspections rather than permanent installation. A survey of the water distribution system would be performed on 3 to 5 year intervals. In the Echologics LeakFinder and SebaKMT Correlux system, sensors are installed on hydrants or valves and the approximate locations of leaks are determined. This is followed up by utilizing a listening device to pinpoint a leak’s location for repair.
This demonstration is currently underway at the U.S. Army Engineer Research and Development Center in Vicksburg, Mississippi.
Initial results from the test bed show that the majority of known leaks have been detected to a location within 4 feet, and leaks as small as 1 gallon per minute have been detected. Further testing and analysis is ongoing.