The average water loss in the Danish water distribution network is below 10 %. This level is among the lowest worldwide, and reducing the loss of drinking water is a global focus area
Together with DTU, the water suppliers Nordvand and HOFOR and a number of other industry partners, AVK has joined the LEAKman partnership. The purpose is to implement state-of-the-art water distribution by using high-technology products and techniques and by tying components and software together into integrated solutions. The goal is to minimise water loss and an important part of this project is effective tracking and management of leakages.
As part of the LEAKman project, the two water suppliers Nordvand and HOFOR have each selected two areas where noise loggers will be installed. Automatic tracking ensures that leakages are quickly identified. This does not only minimize the water loss caused by leakages; it also prevents the damage from escalating and causing more serious financial consequences. At Nordvand they have already seen positive effects of the automatic loggers, as only a few days after installation, two leakages were identified.
Automatic tracking and reporting
Leif Koch A/S has developed noise loggers for automatic tracking. The leak noise behaves in a special way and can be recognised and distinguished from background noise by a microphone in the noise logger. Listening to the intensity and the frequency of the noise, the logger can identify and locate the leakage.
The noise loggers can be programmed to 10,000 listenings at a pre-defined time, typically between 2 am and 4 am when consumption and background noise are at a minimum.
The water supply network
The water distribution network is massive and it can be difficult to get an overview of all details. The pipe network in modern water distribution systems is therefore sectioned into smaller areas called District Metered Areas (DMA) including between a few hundred and a couple of thousand consumers. Each section has one primary entrance and a number of secondary entrances for use in emergencies.
The sections need to be well defined and separated by shut-off valves – typically gate valves. It is extremely important that these valves are reliable and completely tight because otherwise you will not be able to know if water is lost due to leakages in the section or if it simply disappears to the neighboring section.
The signals will be sent as audio files to the water supply management system. If the logger recognises a leak noise, the audio file will contain a warning, and the water supply can then locate the leakage.
Placing the noise loggers
Each section of the distribution network is provided with a number of valves in order to be able to isolate a section which is as small as possible in case of pipe bursts or the need for establishing new pipes. The valves are spread across the whole section and thus, it is an obvious opportunity to place the noise loggers together with the valves.
The valves are mounted on the pipes, and here they are in contact with the water path. On top of the valve, there is an extension spindle allowing the valve to be operated (open/close) from street level. The valve and the extension spindle have metallic contact, and as sound is transported optimally through metal, this location provides optimal conditions for noise loggers.