A Water Leak Correlator , also known as a water leak listening device is a powerful electronic device to locate leaks on pressured pipes, where the rough location of the leak is unknown and the distances relatively high. Two (or more) sensors are placed in contact with the pipe on both sides of the suspected leak. Those sensors record and transmit the sound by radio to the processing unit. Mathematical algorithms are used to determine the exact location of certain noise profiles (such as hissing leak sound) on the pipe, by correlating the noises that reach both sensors and measuring the difference it takes to travel on the pipe from the leak location to each sensor.
Leak correlation equipment is becoming ever more popular in the restoration sector as an additional professional service to their armoury
Many of today’s water distribution networks have permanently installed listening devices at strategic locations. Using frequency analysis and cross-correlation methodologies, permanent listening devices can help to detect leaks as they occur. Frequency analysis measures and filters out ambient noise that interferes with leak identification.
Cross correlation can be used to identify the exact location of a leak. It uses two sensors and the leak must be located between the sensors. In cross correlation, the time delay of the leak noise between the two sensors is combined with the speed of sound in the specific type and size of pipe to determine where the leak is between the sensors. Unfortunately, local factors such as soil condition can vary along the length of a pipe making it challenging to determine the exact speed of sound. Placing sensors closer together throughout the distribution pipeline is one way improve the performance of leak detection systems.
Advantages of Acoustic Correlating Technology
- Detects leak sounds incapable of being detected by the human ear.
- Survey multiple lines at once for commercial or municipal water systems.
- Sometimes detects leaks in non-metallic pipes.
- Noisy areas can be surveyed by taking readings at night.
Limitations of Acoustic Correlating Technology
- Not all leaking pipes produce leak sounds capable of being detected.
- Cannot detect leaks unless the water pressure is high enough.
- Sometimes it cannot detect leaks in non-metallic pipes.
- Even at night some areas are too noisy to collect readings at.
Trotec LD20HC Correlator
Correlation is a computer-assisted method, with which very accurate leak detection can be carried out.
From each leakage point, a sound is produced, which spreads through the pipe and transfers it to hydrants, fittings or sliders. At up to three contact measuring points, the sound is captured by the high-sensitivity signal pick-ups and transmitted to the correlator via the LD radio transmitter.
The LD20HC calculates the exact leakage position from the transit time difference of these signals taking into account the material, the pipe diameter and the length of the measuring path.
While leak detection with other electroacoustic methods – especially with long pipelines – can only be carried out with difficulty due to disturbing factors such as weather, buried depth of the tube or a high noise level, a leak point can still be easily detected by correlation in such circumstances.
The LD20HC combines quality engineering “made in Germany” with the latest technology for leak detection in pipelines or drinking water networks and is thus an ideal standard equipment for water suppliers and metrological service providers.
At leakage points, water emerges under pressure, producing an outflow noise that moves in both directions through the pipelines and is detected by highly sensitive sensors, which can be installed at accessible points such as hydrants or valves.
Because the type of water pipe always affects the sound propagation, the material and diameter of all pipes can be specified in the LD20HC and up to 20 pipe sections can be examined with only one measuring operation.
The recorded signal is amplified and transmitted to the correlator by radio, which allows an application of 256 freely selectable filters to the signal.
Can also be used for acoustic leak and pipe detection
Different body or floor sound microphones can also be connected to the LD20HC for listening. In combination with the floor sound microphone, the leak location previously determined by correlation, can be verified. Further, all other acoustic leak and pipe detection can be performed.
Guterman AQUASCAN 610
The AQUASCAN 610 is the world’s first cordless leak noise correlator and provides highly accurate and error-free leak pinpointing. The combination of high performance, elegant design, compact size and advanced features make this the most popular leak noise correlator available. The AQUASCAN 610 is highly accurate and extremely portable. It is designed to withstand daily use, rain or shine, in outdoor conditions.
Guterman AQUASCAN TM2
AQUASCAN TM2 – TRUNK MAIN & PLASTIC PIPE CORRELATOR
Powerful high-end touchscreen correlator designed specifically to find leaks on large diameter pipes over long distances – intelligent, non-intrusive and user-friendly. This correlator is currently the most advanced correlator in the industry.
Eureka3
Eureka3 provides high-performance leak noise correlator and leak noise logger of multiple pipe material.
Powerful Adaptive Filtering
The Eureka3+ incorporates the new Adaptive Filter. This operates live in the frequency ranges selecting the optimum correlation. This enables location of difficult leaks missed using conventional filters. The Eureka3+ option also features post-processing such that re-analysis of results can be carried out on and off-site.
Key Features
- Easy to use with touch display
- Online and offline correlation
- Pinpoint location using multi-sensors or ground microphone
- Highly durable and adaptable leak noise correlator
- Multi-correlation without pipe parameter input
Additional Features
- Optional direct transmitter connection to pipe (street-working friendly)
- Rapid leak detection – before entry of pipe details
- Unwanted noise suppression
- GPS leak and transmitter locations saved
- In-case battery charging from mains or vehicle
Sewerin SeCorrPhon AC 06
SeCorrPhon AC 06 – Radio transmitters and Piezo accelerometers
The noise from the microphones is transmitted to the central control processor by two powerful radio transmitters
- Lightweight radio transmitters which can easily be carried in one hand by the antenna carrying buttons
- Automatic on/off when the microphone is plugged in/out – no danger of running the battery flat by mistake
- Automatic best amplification level selected when microphone connected
- In built low pass frequency filter – Ideal for plastic pipes; It highlights and emphasises sounds in the range 0-300 Hz which is where leak noises are more likely to be propagated on this material
- The receiver and radio transmitters can all be charged in the closed case doing away with the nuisance of having multiple component parts plugged into various sockets around your office.
- Charging can also be carried out in your car or van via the 12V cigar lighter lead
Sewerin SeCorr 300 – PC based correlation
The SeCorr® 300 is Sewerin’s new fully digital water leak correlator offering unprecedented performance in finding water leaks even on plastic pipes and trunk mains.
The fully digital signal processing combined with the advanced microphones largely eliminate the limitations experienced with conventional analogue correlators.
Notebooks, Toughbooks and desktop PCs can be used to analyse the measurements.
The SeCorr® 300 correlator offers you the best chance of finding those hard to locate water leaks, even under the most difficult of conditions where conventional correlators have reached the end of their detection limits.
