The Federal Energy Management Program (FEMP) identified acoustic leak-detection noise loggers as a water-saving technology that is relevant to the federal sector, is commercially available, and offers a significant water-savings potential.
This overview provides agencies with key information to deploy innovative products and systems that may otherwise be overlooked. It also helps agencies identify water-efficient technologies for consideration when entering into energy savings performance contracts and utility energy service contracts.
FEMP considered the following when selecting this technology.
- Underutilized in the federal sector
- Broad applicability across the federal sector
- Water and cost savings potential
- Market availability
- Produced by multiple manufacturers
- Ease of installation/suitable as a retrofit
Identifying and locating distribution system leaks can be difficult. However, targeting problem areas for repair or replacement is critical for effective resource management and water conservation. Acoustic leak-detection technologies use sound waves to help locate leaks in distribution systems and prioritize leak repair by identifying the largest leaks.
Leaks create a distinctive noise as water leaves the pipe, with smaller leaks producing a higher-frequency sound and larger leaks typically having a lower-frequency sound.
Noise loggers are a specific type of acoustic leak-detection technology that includes a listening head and digital recorder in a single sensor. They can be attached magnetically along the distribution system (e.g., key junctions, main valves, or hydrants) and left in place for extended periods or moved as needed to record noise levels and detect leaks.
Acoustic leak-detection noise loggers work well for long-term recording because they eliminate the need for an operator during the recording. However, analyzing the data requires experience or specialized software to characterize and differentiate leak sounds from those of normal water flow through the distribution system and pumps and any other background noises such as construction or traffic. The user can set the sampling frequency from once per millisecond to once per minute, and the logger can store the data for several days depending on the unit’s data storage capacity. Some models feature radios allowing the data to be downloaded remotely.
Acoustic leak-detection noise loggers work best on cast iron, ductile iron, steel, concrete, and transit pipes. They will work on PVC pipe. However, longer data collection periods may be necessary (source: Control and Mitigation of Drinking Water Losses in Distribution Systems, EPA 816-R-10-019, November 2010).
Proven Savings Potential
Tobyhanna Army Depot deployed leak-detection noise loggers on its aging distribution system where sections of pipe are more than 60 years old. Six previously unknown leaks were found, totaling approximately 90,000 gallons of water loss per day or 26% of the average daily water use at the installation. The site targeted areas for repair and installed meters along with ongoing leak detection using noise loggers to reduce its loss rate to less than 11,000 gallons per day, resulting in a 20% reduction in overall water use. This work earned the army depot a 2012 Federal Energy and Water Management Award.
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