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Process purging
Ensuring purging
Ensuring purge air
monitoring
Checking purging
medium
requirements
Purging after
installation
16
Process purging is a continuous purging process used to protect the optical
surfaces (lenses) against the build-up of dirt. This process also cools the
transmitter and receiver units.
The purging medium is connected to the purging flange and flows into the
process, where it mixes with the process gas.
Ensure that a purging flange is fitted for both the transmitter unit and the
receiver unit.
Ensure that the purge air can be monitored. Failure of the purging process
can result in irreversible damage to the lenses and cause the transmitter and
receiver units to overheat.
The following are suitable for use as purging fluids, depending on the applica-
tion (see data sheet):
Compressed air or
Nitrogen
Compressed air quality: dry and oil-free (in accordance with ISO 8573.1, Class
2-3)
Recommended pressure: typically around 25 % above the process pressure.
Recommended flow rate: 20–100 l/min.
If...
all requirements are met
one or more of the requirements
are not met
To avoid damage to the parts of the gas analyzer affected by the process gas,
process purging should be commissioned right after the gas analyzer is in-
stalled.
Operating instruction LS4000 for NH
then...
the receiver unit and the transmitter unit
can be installed.
the receiver unit and the transmitter unit
must not be installed.
and H
O
3
2
OI/LS4000/NH3/H2O-EN
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