Xmic
24/01/05
MAN-095-0001 Revision B
© Palmer Environmental Ltd 2005
Page 19
or at regular positions on the ground until you have identified the area of maximum
noise level.
Note
: When you are listening on pipe-fittings the location of the point of maximum
noise will probably not indicate the leak position, only the fitting closest to the leak.
The noise level will also appear stronger where there is less thickness of ground or
other material for it to pass through. The leak noise will follow the path of least
resistance.
Pinpointing the leak position
Pinpointing the leak position involves a process of comparing a number of leak
noises. Select the most suitable sensor device; the microphone foot for hard ground
surfaces or the hand probe for soft ground.
Operate the ground microphone and adjust the headphone volume control to a
comfortable listening level. Once you have listened to the noise through the
headphones, mute the headphones and move the microphone foot or hand probe to
the next test position.
Repeat the sequence to listen to each of the test locations moving along the pipe
route in the direction where signal strength is increasing. If the leak noise level falls
you have passed the leak and should go back and reduce the distance that you move
between measurements. The loudest leak noise will then indicate the location of the
leak bearing in mind the ground conditions already mentioned.