Helium Detectors are used primarily in leak detection situations where sonic detection methods are not effective (inability to maintain pressure in the line or soil saturation). Instead of “listening” for the sound of escaping gas from the leak, the Helium Detector actually detects the leaking gas itself. Because Helium has a small molecular structure and rises it will often make its way to the soils surface very close to where the leak is. A Helium Detector identifies trace amounts of the gas and provides an indication to the user of its presence through an audible alarm and a LED bar graph.
Although Helium can come right through concrete it may “pool” under the deck and make its way through nearby cracks or expansion joints first. In large expanses of concrete it may be helpful to drill small holes in the deck along the path of the line to help assure a more accurate leak detection.
To save a tremendous amount of time and to do a quality leak detection job it is necessary to have a piece of equipment that can read at least 50 parts per million. The helium detector has a vacuum pump which “sniffs” (draws in) the helium content of the air by passing it through a crystal. The amount of helium detected is read out on a digital display. Machines that can only read down to 200 to 300 parts per million are considerably less expensive but will not be able to locate half of the broken lines. Machines that can read at least 50 ppm can cover 1,000 sq. ft. in less than thirty minutes.
Some facts on helium gas that make it a prime candidate for detection:
- A. Helium is the second smallest molecule
- B. Helium is lighter than air so it will rise
- C. Helium is non-toxic, inert and only 5 parts per million in the atmosphere.
- D. Helium can travel through concrete, stone, carpet, carpet pad, tile floors, and wood floors (sheet vinyl is a little more difficult) making it a very reliable leak detection tool.