Hong Kong was the first city in Asia to take advantage of the advanced leak detection capabilities of the Permalog noise loggers, with an initial deployment back in 1999. The loggers are placed on water pipes where they listen for the sound made by leaks, log the data and then transmit it for further analysis. This enables water companies to identify leak areas quickly and efficiently; saving time, money and water by enabling a rapid, accurately-targeted response to repair the issue.
In Hong Kong, the Water Supplies Department (WSD) is in charge of maintaining the 7800km of underground water pipes in the city, and has a 15-year rehabilitation program costing billions of HK dollars to repair, upgrade and modernise the network. Their target is to reduce burst incidents from 2500/year in 2010 to 1000/year by 2015, and to decrease the leakage rate from 25% to 15%. Out of the 1100 cross-road pipes, around half are very old, and at increased risk of damage and disrepair.
When a pipe in the busy Wanchai district burst recently, the Hong Kong government identified a further 600 sites around the city where very old pipes run under busy streets, and deployed a new batch of Permalog+ noise loggers to watch for, identify and locate any leaks in these areas.
Permalog technology is made and developed in the United Kingdom by Halma Water Management (HWM-Water Ltd), and the company’s distributor in Hong Kong is Allied Power Technology Ltd. Allied Power has supplied over 800 sets of Permalog+ units with SMS repeaters to the region, and also has a contract with the local government to analyse the data gathered from the system.
When deployed with SMS repeaters, the Permalog+ devices can function together as a nodal network, with all data being automatically transmitted back to a ‘home station’ – in this case Allied Power’s offices. Every morning, the company receives the leakage data for each of the install sites, and makes recommendations to the WSD based on this information.
Davis Li, Managing Director, said: “We manage a huge amount of data every day, which has to be organised and presented clearly. Because the noise loggers are on busy roads for this project, there is quite a lot of interference from road noise, which can complicate our job. The main challenge of this monitoring work is to localise a leak when a correlation is simply not possible. In these situations, we usually use the Permalogs’ Aqualog function to differentiate interference and help identify the leak location.”
When in Aqualog mode, a Permalog+ logger will measure and log acoustic data at preset intervals over an extended period of time, typically at night to minimise the traffic noise. This data can then be presented graphically so trends, anomalies and incidents can be clearly identified. This effectively displays whether or not the noise is caused by a leak, since any leak noise will be consistent.
The combination of the automated leakage data transmission for general leakage alerts, and in-depth on-site analysis with Aqualog, means that leaks can be quickly identified and problems repaired before they cause major disruption or damage to Hong Kong and its residents.
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