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Operation
Your FTIR Heated Valve Drawer may or may not have each of these features. The specific
configuration of your drawer determines which controls you have and how they are arranged.
The system is available in 2 basic configurations:
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Manual Pressure Control: Set the gas cell pressure and sample flow rate by manually adjusting
the valves and flow meter positions. If you switch between Sample and Span gas inputs, you
must reset pressure and flow values because of the different back pressures. You may also need
to correct the pressure and flow occasionally when they naturally drift.
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Automatic Pressure Control: The gas cell pressure and sample flow rate are controlled
automatically using a variable pressure control valve. Configure the set point with a pressure
controller. The variable valve maintains the gas sample pressure at a constant value, even with
changes in back pressure or between different input selections. With the Automatic Pressure
Control option, you can use custom sampling manifolds with multiple streams and control the
input sample selection through a programmable logic controller (PLC).
The Manual Pressure Control and Automatic Pressure Control configurations have different sample
tubing connections on the rear panel of the Gas Control Panel. Verify the configuration of your
system before installing the tubing connections.
Manual Pressure Control Configuration 36
Automatic Pressure Control Configuration 42
Using an eductor to generate vacuum 48
Using the temperature controllers 50
Sampling procedure for the Modular Gas System 52
Chapter 4
Thermo Scientific Modular Gas System User Guide 35