SubSurface Instruments LD-18, Руководство по эксплуатации

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6. Method for water leak detection
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When water leak occurs from a water pipe buried under the ground, the water jets out with force because of
the water pressure in the pipe. Such water leak accompanies compound sound involving four elements,i.e.,
(1) water flow sound, (2) impact sound, (3) to-pipe friction sound and (4) pipe vibration sound. This com-
pound sound is called water leak sound in general.
The acoustic quality of the water leak sound that passes on to the ground varies by conditions such as situation
of occurrence of water leak, soil quality, pipe type and depth. In other words, the acoustic quality varies
because four elements of compound sound are combined with varied conditions, and there is no case where
the frequency distribution shows a constant value.
To locate a point of water leak, this water leak sound is pinned down on the ground through a water leak
detector, and total judgment is made by man’s sound detecting sensation as combined with situation of the
field.
Search for water leak sound while moving the pick-up on the ground along the route of the buried pipe.
Carefully determine the point at which the level bar display becomes the maximum, and mark a <maximum
point>.
There is a case that the point of the maximum level which is indicated is not right above the point of water
leak, depending on conditions in the ground and road surface.
[Hardware]
Pipe vibration sound
Impact sound
Water flow sound
Friction sound
Maximum sound
sound level
Leak point
Leak sound