Thermo Scientific FTIR, User Manual

Page: 58 / 83

A
Temperature controllers
B
Flowmeters
C
Sample control valve
D
FTIR outlet control valve
E Inlet and Outlet needle valves
F Power switches
G Calibration gas selection valve
❖
To collect time-series data from a sample gas chamber
Note This example uses the Manual Pressure Control version of the ModGas system. The
procedure to adjust the Automatic Pressure Control version is similar, but the front panel controls
are a bit different. The sample gas pressure and flow rate are balanced at the target levels using
the FTIR Inlet/Outlet restriction valves together with the “FTIR Flow to Vent” flowmeter.
1. Turn the ModGas system components on.
a. Turn on the Sample Pump and Power to Heaters switches. This provides the heating power
to the temperature controllers for the Heated Sample Line (HSL), internal Valve Oven, and
Heated Transfer Line (HSL, or “Tube to FTIR”). Wait until these stabilize at your target
temperature.
The diaphragm pump should be on when using the sample, to keep a flow of gas through the
sample cell. This minimizes any issues from soot or heavy hydrocarbons coating onto the
gold mirrors of the FTIR gas cell.
2. Adjust the flow rate and pressure control settings to achieve a stable gas flow at 650 mmHg
pressure at 4 liters/minute flow rate.
a. Ensure that the sample control valve is still in the Open Sample position and the calibration
gas selection valve is set to the Off position.
b. Set the FTIR Inlet Restrict and FTIR Outlet Restrict valves set to wide open, and open the
FTIR Flow to Vent flowmeter to allow maximum flow.
Thermo Scientific Modular Gas System User Guide 53
Operation