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4.3 M
(L
OBILE
IFT AND
Devices used in this way are typically deployed at a site, left over-night for the leak
evaluation to occur, and then collected from the sites on the following day. Radio range
is not an issue, as the loggers are removed from their installation sites; this allows the
data to be collected at a short-range. After downloading Leak-status data and any other
required data, the loggers are then deployed on new sites and the cycle re-starts.
4.4 P
ERMANENTLY
These loggers are permanently installed at a site, typically by attaching to a metal valve
or hydrant, etc. A further consideration in their location is that the data from the logger
has to be collected over a radio-link with a limited range. Usually the loggers are located
so that they are able to be readily detected whilst passing by them at a modest speed.
(This can be tested by doing a trial-run after installing). The data can also be collected by
passing close to the installation site on foot.
Once a day (the user may set the time) the logger makes measurements of the pipe
noise and evaluates if a potential leak exists. The logger device is also set (prior to
installation) to have a patrol window that matches the possible data collection times.
When within the patrol window, the logger enables the radio-link and sends periodic
broadcasts of information. This identifies the logger and also includes the following:
The leak status (i.e. Leak/No-Leak),
•
Noise level maximum,
•
Noise spread.
•
Any further data (e.g. a sound recording) must be specifically requested by establishing
a 2-way conversation with the logger, and takes longer to download.
Any drift in the clock accuracy is insignificant for the task of confirming whether the
sound from within the pipe does resemble the sound produced by a leak; the precise
time the recording was made is not important. Any sound files collected will not be
suitable for correlation purposes as the clocks of each device will be free-running, and
will not be sufficiently aligned after several days. To produce files for correlation
purposes, setup and use a scheduled sound recording - see section 4.2.
5 U
-
SER
SERVICEABLE PARTS
No user-serviceable parts exist except those listed below:
Antenna.
•
o Only use antenna recommended and provided by HWM.
o Refer to Safety and Approvals Information document.
S
) L
HIFT
OGGERS
I
L
NSTALLED
OGGERS
13
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