The Tune window Vacuum menu D-5
The Analyser Ion Gauge display shows the pressure in Analyser 1 or
Analyser 2, depending on the currently selected option in the Vacuum Control
dialog box.
You can operate only when all the pressures are below the relevant trip levels.
You can specify the trip settings for the Source and Inlets Pirani gauges, and
Source Ion Gauge in the Vacuum Control dialog box.
When the pressures are below the trip levels, the LEDs on the instrument’s
status switch panel are green; if a trip occurs, the appropriate LED display’s
red or orange.
See “Controlling and monitoring the vacuum pumps” on page D-5 and “Status
switch panel” on page 1-8.
If any Pirani gauge output pressure reading exceeds the trip level, the
relevant fine pump is turned off. This trip has some hysteresis in its operation
thus the pressure at which the trip resets when the vacuum is improving is
lower than that at which it trips out.
If any ion gauge output pressure reading exceeds the trip level, the
instrument is automatically shut down.
The Source ion gauge display has an additional solvent trip level, denoted by a
yellow sector. This trip turns off the source filament and accelerating voltage
when the pressure in the ionization source rises sufficiently high to cause
arcing but is not high enough to activate the vacuum trip. For example when
solvent appears during a sample injection through the GC column. This trip is
non-latching and restores the source filament and accelerating voltage when
the pressure recovers. This trip also has some hysteresis in its operation.
To monitor the instrument vacuum
1. Select the required analyzer ionization gauge. See page D-9.
2. Click Vacuum > Monitor.
3. In the Vacuum Monitor window, observe the Pirani and ionization gauge
outputs (in mbar) for the various parts of the instrument.
See “Controlling and monitoring the vacuum pumps” on page D-5.
Controlling and monitoring the vacuum pumps
Click Vacuum > Control to open the Vacuum Control dialog box.
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