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Vari OmniStar
8.3 Design
The major components of the Vari OmniStar can be seen in Figure 8-2.
Figure 8-2 Vari OmniStar major components
Figure 8-3 Vari OmniStar functional block diagram
The Vari OmniStar with control valve EVR 116 and valve controller RVC 300 allows for
regulated sampling of gases in the pressure range between 5E-3 mbar and 1000 mbar.
The system is connected to the process chamber to be sampled by a DN 16 KF flange.
The gas flow rate from the process chamber into the analysis chamber of the Vari
OmniStar is controlled by an EVR 116 control valve with RVC controller and two
electromagnetically operated shut-off valves. The analyzer pressure to be regulated is
measured by a full range PKR 251 total pressure gauge mounted to the analysis
chamber. If the process pressure is less than 5E-3 mbar then the system will not achieve
regulation yet will continue to sample with the vari valve open, the high-conductance
valve open, and the bypass valve closed. If the analyzer pressure is measured as being
above 1E-4 mbar then the valves will automatically close.
The status of the EVR 116 control valve as well as those of the two electromagnetically
operated shut-off valves are indicated by the GSD 320 front panel. Depending on the
process pressure, the control valve as well as the shut-off valves are set to allow for
optimum pressure reduction with minimum gas fractionation into the analysis chamber.
The Vari OmniStar is designed to track gradual changes in pressure and may not be able
to handle extreme pressure changes or bursts.
OmniStar with
integrated control
valve EVR116
DN 16 KF
connection
flange
RVC300
PrismaPlus
QMA 200
IS
PKR
Turbopump
with interstage
pumping port
Diaphragm pump
Vent valve
HEATER
M
RVC 300 Controller
EVR 116 Regulating Valve
DN 16 ISO-KF
v
v
MINI valve
Special electro-
magnetic valve
Orifice
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