Northern Utility Services

Leak Detection


Major Water Leak

Water Leaks are costing companies thousands of dollars every year.

Little Leaks = Big $$$

Leak Detection makes business sense, and Northern Utility services provides state-of-the-art leak detection services throughout the State of Alaska. Whether you simply need to find a service line leak, survey an entire distribution system, or obtain an emergency leak detection, our trained operators are equipped to meet your needs.  Our leak detection efforts have saved our customers millions of dollars by eliminating systemic losses, expensive exploratory excavations, and by providing detailed reports to justify grants and low interest loans.   Our successes have ranged from  locating a tiny leak on a mile of  48 inch Steel main to locating a leak on HDPE Arctic Pipe.

Equipment:

Northern Utility Services has two different logging correlator systems at its disposal.  The Zcorr system manufactured by Itron Flowmetrics is a high quality digital leak correlator/logger  well suited for quick surveys of suspected lines and distribution systems.  The SoundSens i, is also a correlator/logger system that excels in locating difficult to find leaks where detailed analysis and frequency filtering is required.  Both systems capitalize on the speed and processing power of a PC to analyze the acoustic data.

Leak DetectionLeak Detection Process:

As part of our service, we provide an Initial consultation to learn system layout, leak symptoms and other information that may provide clues to narrow the search. Next, we utilize acoustic listening equipment to listen on valves and service lines to narrow down the search area. Finally, a leak noise correlator is used to pinpoint leak locations.
In the case of a system-wide leak survey, leak noise loggers are deployed throughout the system to record leak noise and develop a leak noise profile for the entire system. Leaks are then pinpointed and a comprehensive report is prepared to communicate the findings.

Methods of Leak Detection:

Acoustics:

Before using correlation (as described below), we use a high quality digital listening device to quickly survey the target area to identify the general location of the leak. In larger distribution networks, a series of correlating loggers will be deployed throughout the system to narrow the search area.

Correlation:

Leak Correlation Theory

Detail of How Correlation Finds Water Leaks

Leak Noise Correlation is a method for finding and pinpointing leaks in pressurized water pipes. A leak in a pipe under pressure creates noise that travels along the pipe, its contents, and through the surrounding ground. When two highly sensitive microphones are attached to a pipe with a leak, the sound from the leak takes longer to travel to the microphone furthest from the leak. By utilizing sophisticated software analysis tools and known sound travel speeds in different pipe sizes and materials, leaks can often be located within feet or even inches.

Complications:

Although leak noise location is a finite science, many variables can cause inconsistent or inaccurate results. By eliminating these variables, leak detection efforts are more likely to provide accurate results. These variables are:

1. Pipe types, locations and depths. If location, or pipe routing is unknown, Northern Utility Services is equipped to locate underground piping. However some pipe materials can be difficult or impossible to locate using standard methods, and as a result, only a general leak location may be possible

2. Ambient Noise. Although our equipment employs sophisticated noise filters, ambient noise can affect results of leak noise correlations. To eliminate excessive noise, our leak noise loggers are capable of delaying the noise recording until the most quiet time of day or night.

3. System Usage. Water flow in the system causes noise of differing degrees, and can produce erroneous or confusing results. To minimize the effect of system usage, our leak noise loggers are capable of delaying the noise recording until a time of day when normal usage is minimal.