34 tina83e1-d (2018-12)
Measurement Principle, Measuring Behavior
The gauge consists of two separate measuring systems (Pirani
and cold cathode system according to the inverted magnetron
principle). They are combined in such a way that for the user,
they behave like one measuring system.
The optimum measuring configuration for the particular pressure
range, in which measurement is performed, is used:
10
-3
mbar
10
-2
mbar
1000 mbar
1×10
-9
mbar
Cold cathode Pirani
• The Pirani measuring circuit is always on
• The cold cathode measuring circuit is controlled by the Pirani
circuit and is activated only at pressures p < 1×10
-2
mbar
As long as the cold cathode measuring circuit has not ignited,
the measuring value of the Pirani is output as measuring signal.
4.5 Gas Type Dependence
The measurement value is gas dependent. The pressure reading
applies to dry air, O
2
, CO and N
2
. For other gases, it has to be
corrected:
• (MAG5xx → 19)
• (MPG5xx → 21).
If the gauge is operated with an INFICON controller, a calibration
factor for correction of the actual reading can be applied (→
of
the corresponding controller).
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