When a pressurised water pipe develops a leak
the water flows out it into the surrounding
soil at high speed, which causes:
The pipe material to vibrate at the exit point.
This vibration, or sound, is transmitted by
the pipe. This “noise” (called structure-borne)
can be heard with the AQUAPHON® A 100 even at
remote contact points, e.g. valves.
The
water jet and the pipe, in the vicinity of the
leak, also induce vibration into the surrounding
soil. This “noise” (called ground-borne) is
transmitted to the surface, where it can be
picked up by the AQUAPHON® A 100.
The
importance of listening
Combined
with the advantages offered by the graphics
of the integral LCD the human ear remains an
important tool for assessing incoming noises.
Practice enables noises of different types and
tones to be differentiated and actual leak noise
to be distinguished from extraneous noise. To
assist the operator the AQUAPHON® A 100 is supplied
with headphones that provide outstanding sound
reproduction.
Preliminary
location using the test rod
In
metallic pipes structure-borne sound is transmitted
over particularly long distances. This makes
the test rod very effective for preliminary
location.
Location
with the ground microphone
Structure-borne
sound is not transmitted very well by non-metallic
pipe materials. Taking readings at the valves
with the test rod may not lead to satisfactory
results. In these cases, by using the ground
microphone, the sections between valves should
also be checked.
Using
the ground microphone at regular intervals enables
the leak to be located with sufficient accuracy
for confident excavation. The AQUAPHON® A 100
shows a precise display comparison of the noise
levels between locations.
Is
the noise getting louder or quieter? What is
the trend? The LCD digital and analogue display
is of great assistance, especially for beginners
or less experienced operators, in answering
these questions.
The
hearing protection function
When
developing the AQUAPHON® A 100 an important
consideration was providing the operator with
protection from accidental exposure to high
noise levels. With other instruments an uncomfortable
sound level can be heard when the test rod slips
from the contact point, or the headphones are
activated too soon, or not soon enough, or something
falls close to the ground microphone.
A
novel technology makes this danger a thing of
the past. The incoming noise is constantly analysed.
When a very loud noise is picked up the sound
in the headphones is immediately muffled. If
the noises increase even further, the headphones
finally are switched off completely.
Once
this noise source has ceased the AQUAPHON® A
100 automatically reverts to normal. The hearing-protection
function can be adjusted to suit the wearer´s
comfort in any given environment.
The
filter-optimisation function
The
filter-optimisation function of the AQUAPHON®
A 100 allows it to detect a leak even when the
sound is very muffled.
The
receiver takes a noise sample with the ground
microphone. This is automatically analysed and
the instrument automatically sets the optimum
frequency range to render the sound of the leak
particularly clear.
