Thermo Scientific FTIR, User Manual

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the N2/Zero gas means that the gas cell pressure and flow rate may show higher values with
N2 than they do from “pull” samples from the sample gas chamber.
c. Uses the Calibration Flow flowmeter to adjust the flow rate of the N2/Compressed Air
sample. Turning down the flow rate of the pressurized N2/Zero gas will bring the ModGas flow
in balance with the valve settings for gas samples through the Sample inlet line to reach the
650 mmHg target value.
d. Once the N2/Zero gas flow is stabilized at 650 mmHg, use OMNIC software’s Collect/Collect
Background command to collect your background spectrum. Background spectra are
typically set to signal average 64 scans, which helps to reduce baseline noise and improve
minimum detection limits (MDL) for the components in the sample gas.
4. Collect Time-Series Spectra using OMNIC.
a. When the background collect is completed, turn the calibration gas selection valve back to
Off, and the sample control valve to Open Sample.
The pressure/flow should return to the target 650 mmHg/4 liters per minute set up previously,
but you may need to make some small adjustments.
b. You are now ready to begin sample collection. Refer to the OMNIC Series for Gas Monitoring
guide to step through the software commands to collect, store, and analyze time-series data
files.
Thermo Scientific Modular Gas System User Guide 55
Operation