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Posted: Monday 27th November 2017

Ferret Leak Location technology started development in 2008 as a technique primarily designed to find leaks on plastic pipes. Accurately locating leaks on plastic pipe, particularly small bore service connections, has historically been a challenge as plastic does not transmit leak noise as well as metallic materials, thereby limiting severely the potential to utilise more traditional acoustic based systems. Adding to that the challenges of locating the alignment of a plastic pipe to be able to use existing acoustic leak location or other methods, has long made finding leaks on this material a significant issue for the water industry.

Having completed development and been used across the water industry since 2012, Ferret technology is now a proven system for reliably locating leaks over a distance of up to 50 metres on not just plastic but also lead and copper pipes of between 10 mm to 45 mm internal diameter.

From October, 2017 ferret Technology Ltd is launching the next generation Ferret Leak Location system with its FLL-SYS-01-A model.

With modifications based significantly on industry feedback and changes in other technology the new unit is designed to be lighter, manually operated, self-serviceable and more affordable than the previous model. Furthermore, the new Ferret system has the option of adding a locator sonde just behind the leak detection head to better assist site crews with pin-point precision location of any leak to within a few millimetres.

The new Ferret Leak Locator system comes with Inlet and Outlet Connection hoses; a Universal Coupler Kit for 15 mm to 35 mm diameters; a pack of 3 Ferret Heads (the Leak Location sensor) - one each of size 0, 1 and 2; a carry bag for ease of storage and transport of the equipment and other accompanying equipment.

Also available are various equipment packages, where measuring and location equipment and packs of replacement Heads are included in a variety of bundles making the initial outlay even more attractive to water companies and contractors.

The new Ferret Leak Locator is designed using food grade polyurethane materials and is only 310 mm long by 270 mm wide by 370 mm high and weighing just 10.5 kg, making it highly transportable and useable by a single operator.

It works with a maximum inlet pressure of 10 bar (145 psi) and an outlet pressure of maximum 5 bar (72.5 psi). It does require a minimum working pressure within the test pipe of 0.5 bar (7.2 psi) to work effectively. The Ferret Head used for the Leak Location process can work up to a maximum of 6 bar (90 psi).


The Ferret system uses a very simple hydraulic principle to pinpoint leaks to within a few millimetres along a pipeline using the existing water pressure in the pipe to drive the Ferret Head forward. The concept of Ferret utilises hydraulic forces to push this inflatable plug down the length of the water pipe under investigation. The plug acts like a moveable valve, stopping automatically when the plug passes a reasonably sized leak because some of the water pressure pushing the plug along the pipe is lost through the leak.

For many years leak location gangs across the country involved in service pipe leakage have utilised the cut and cap method. The Ferret process has been described as underground cut and capping but without the associated excavations. The system has also been described as a No-Dig Entry technique given that the Ferret Head can be inserted into the potentially leaking pipe through certain types of meter box without the need for an excavation. A range of fittings is also available for quickly connecting the Ferret to a pipe under investigation.

Once the Ferret Head has been inserted into the pipe, the operator can move it along the pipe, isolating sections of the pipe at any point just by inflating the Ferret Head which then acts like a line valve.

The Ferret Head is attached to the main system by a 50 m long umbilical cord. To start the leak location process, the Ferret Head, comprising a robust balloon is deflated so the water in the pipe can get past it towards the leak in the pipe. The Ferret Head is then inflated with water via the Ferret unit. When the pressure in the Ferret Head is higher than that of the water in the pipe, it blocks the pipe so no water can get past it.

At this point the operator reduces the pressure slowly inside the Ferret Head balloon until a balance is reached between the pressures in the Ferret Head and the water pressure in the pipe, the water in the pipe then pushes the Ferret Head along the pipeline whilst still not allowing water to bypass it.

When the Ferret Head passes a reasonably sized leak, some of the water in the pipe behind the balloon escapes through the leak hole. The pressure pushing the Ferret Head forward drops and the Ferret Head automatically stops moving due to lack of forward force.

Very small leaks, equivalent to a dripping tap can be found using the Ferret Leak Locator. The Ferret Head can be driven along the leaking pipe and stopped at various distances. It is then inflated and effectively closes off the section of pipe between the Ferret unit and the end of the umbilical cord. If there is no drop in pressure shown then the small leak position has not been passed. This process is repeated until there is a drop in pressure and the Ferret Head has passed the small leak. Using this simple pressure test approach the Ferret Head can be moved backwards or forwards until the exact leak location is determined.

A small sonde can optionally be built into the system just behind the Ferret Head which is then activated using a signal generator connected to the Ferret unit. Using standard CAT & Genny pipe tracing equipment, the sonde signal is located from above ground so pinpointing the leak location. With such accurate location of leaks, clients can experience significant cost savings by avoiding unnecessary excavations, reinstatement charges and importantly crew time.

The Ferret Leak Location system has only the Head balloons as consumables, so operating costs in comparison to other technologies are low. There are also no H&S requirements or associated insurance costs to carry a Ferret system on-board a repair van.

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July 2021

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