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4 Water leak detection
In water leak detection the display will be similar to that shown
in the illustration above.
The noise is loudest near the leak and quieter further away.
On the left:
the analog display indicates about 30%: this is the
instantaneous noise value
.
However, the analog
display often fluctuates substantially because
of changing ambient noise. Even a trend can be hard to recog-
nise. This is why the large digital display (figure 16) indicates the
smallest noise value measured at this point so far
(the current
delayed-action value)
. Even if ambient noise grows louder, this
display is unaffected - while if it grows quieter the display falls
further.
The figure 16 is also shown in the analog display as a segment
in reverse video.
The small digital display indicates “0”: as yet there is no value
in memory.
Centre:
the analog display indicates about 60%. The large digital
display (figure 38) indicates a value greater than the left-hand
measurement point. This is an indication that the leak is closer.
The small digital display now indicates “16”: it reminds you of
the result from the last measurement point
(last delayed-action
value)
. This makes it easier to decide whether you have not yet
reached the leak or have already gone past it.
