If a water pipe is not under pressure or the noise from the leak cannot easily be heard then Tracer gas can be a very useful technique to locate water leaks in: Customer Supply Pipes, Underwater Heating Systems, Boilers, Central Heating Systems, Mains Distribution Networks.
The Tracer gas is introduced into the pipe with the leak from a cylinder of gas. The tracer gas used to find water leaks is a mixture of hydrogen (5%) and nitrogen(95%) making it completely safe to use in drinking water supplies being both non toxic and non corrosive. The tracer gas contains hydrogen, which is the the lightest and smallest molecule in the atmosphere, which will exit at the leak point and make its way to the surface where it is detected by the highly sensitive Variotec 460 gas detector.
The pipe, (or any item) with the leak, is emptied of its contents. In heating or water systems drain out as much water as possible; small amounts of water remaining at low points of the system do not dramatically affect the success as the gas is pressurised around the water system.
Ensure the system is sealed. i.e. no gas can escape except via the leakage point
From a cylinder of Tracer gas, (5% hydrogen / 95% nitrogen, supplied by standard compressed gas suppliers), make a suitable connection from the cylinder to the item to be filled with gas.
Pressurise the system to be filled with tracer gas. The pressure will depend on the normal operating pressure of the system being tested for leaks and how high you want to pressurise.
When the cylinder pressure gauge steadies you know that the system is now losing tracer gas only through the leak
With the Variotec 460’s internal sampling pump turned on (speeds up response time) walk over the area to be searched with the Variotec 460 on its most sensitive setting (ppm). Observe the display looking for the location with the highest tracer gas readings.
Move away from the area that showed the highest gas readings and see that the display drops
Return to the area that showed the highest reading and check the gas display once again increases
Check other areas for high readings
Note: The above information is for generic guidance only and is not to be considered as instructions for how to operate or implement the use the Variotec 460
Why use hydrogen as the tracer gas?
Hydrogen, at a level of 5% in a balance of nitrogen, is:
commonly used as a blanket gas in welding so is cheaply and readily available from all the standard gas suppliers
has the smallest and lightest molecules so permeates all surfaces including concrete, tarmac, block paving and grass, rising quickly to the surface
rapidly disperses in air allowing you to hone in quickly to the source
unlike helium leak detection, which has also been used for some types of leak detection tracing, hydrogen is renewable and cheap; helium is finite and expensive
Variotec 460 tracer gas sampling probes
Carpet probes for long stretches of smooth surfaces
Bell probes which concentrate the gas for localising in undergrowth or on smooth surfaces such as kitchen floors
Hand probes both telescopic and flexivle to reach into awkward areas
Cone probes for localisation in bar holes you make in the ground
Charging and carrying the Variotec 460 tracer gas
Parts and accessories are stored neatly in the hard protective carrying case
The Variotec 460 tracer gas may be charged directly from a 12 V cigar lighter socket in a vehicle or from the mains
The detector can be charged whilst remaining in the case
Variotec 460 tracer gas Specifications
Built-in membrane pump
~8 hours (with pump)
Rechargeable or Alkaline batteries
148 × 57 × 205 mm
-20 °C … +40 °C
-25 °C … +60 °C
Operated by jog dial, function keys and menu navigation
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