BG 800 300 BE / A (0105) TPG 300
12
4 Operation
4.1 Measuring with the TPG 300
4.1.1 Power on procedure
Before switching the unit on, check that all plug-in boards,
connection cables, and gauges are installed correctly
(
→
2
9) and that the technical requirements are satisfied
(
→
2
34).
If a break in the protective ground occurs inside or outside
the unit or if the protective ground connection is detached,
the unit will become dangerous. Intentional interruption is
not admissible.
The mains power switch is located on the back panel of the unit.
To switch the unit on, operate the mains power switch (or the
centrally switched mains power distributor in case of installation
into a rack).
After the power has been switched on,
•
the unit performs a self-test
•
it reactivates the parameters in effect before the unit was
switched off
•
all measuring circuits with activated immediate start-up
(
→
section 4.7.9) and all operational Pirani gauges are
switched on
•
the measurement value of the first measuring circuit in opera-
tion is displayed.
4.1.2 Gas type dependence
The measured pressure depends on the gas type present. It is
referenced to nitrogen (N
2
). For other gases please refer to the
characteristic curves shown in the appendix of
&
[3].
4.1.3 Validity of displayed data
If you intend to use the measurement results for control functions,
allow for the time constants of the gauges, possible ignition de-
lays etc., until valid measurements are displayed (
→
&
[3];
[7] ... [10]).
4.1.4 Accuracy of measurement
A generally applicable statement on the accuracy of the meas-
urement cannot be made. The type of gas being measured is a
major factor affecting the accuracy, and so is the current condition
of the gauge.
The accuracy of the gauge at any particular moment can only be
assessed by comparing the results with a reference unit. Calibra-
tion pumping systems are available for reliable measurements,
particularly for pressures under 10
-4
mbar.
4.1.5 Alignment
Cold cathode measuring circuits are factory aligned and require
no recalibration.
Pirani measuring circuits are factory prealigned. For accurate
measurement
→
&
[3].
