Detection of leaks in underground pipes, subterranean galleries and cavities, distribution networks esp. water

摘要

The method uses helium which is of low concentration in the atmosphere so that higher concentrations can be detected readily. It is mixed with the water flowing in pipe being investigated. The gas escapes from faults (12) and, because of its small molecular size and low density, diffuses rapidly and rises as a cone. The gas is detected near the surface using a pipe (13) or a bell (19), connected through a flexible tube (15,15'), to an analyser (17,17'). The analyser may be a specific mass spectrometer. In some cases the pressure of the water system may be raised by 25% to assist the procedure.