Servomex SERVOPRO Plasma, Operator'S Manual

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Plasma Gas Analyzer
72 02001001A_9
You may enter any value between 0 and 2 with a resolution of 0.001. The offset value will
compensate for the baseline drift. If for any reason you suspect excessive temperature drift,
please contact us for exact procedures to be followed.
3.5.3 Operating consideration
WARNING
Before changing the operating background gas, make sure that you
have the selected gas available. It is not recommended to operate
the analyzer under argon background gas selected when helium is
flowing into the analyzer. The flow loop will try to maintain the flow,
but helium does not have the same thermal conductivity as argon.
So, in fact, there will be a much higher flow, the velocity may come
too high in the flow module (thermal bridge), and damage may occur
to this sensor.
Any value entered under calibration menu and all calculated operating parameters will be
saved in the memory when you change from argon to helium or vice versa. Values for alarm
set points, if you have this option, and temperature coefficient entered in the hidden menu will
also be stored.
When you change the background gas selection, a new flow table in the software is used.
The tuning of the flow loop is also changed. Calibration and alarms are saved in the
memory. The signal processing algorithm is also modified accordingly.
There is also some hardware change in the cell design in this version of SERVOPRO
PLASMA.
Differences between argon and helium backgrounds.
1) Starting count value will be different
2) Default sample flow will be different.
Recommended sample flow: Argon

75 cc/min
Helium

75 cc/min
To get the same system overall response time, the by-pass flow, when in helium will have to
be higher.
3) The dual background version is shipped with a metal based moisture trap. If you
operate in argon for a long period, a molecular sieve trap is required.