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Calibration
Periodic System Zero Check
Periodic System
Zero Check
4-2
Omni FTIR Multi Gas CEMS Instruction Manual
spectrum is not as good as the prior one, the system would retain the
original zero background spectrum for the data processing. While collecting
instrument zero background, the system sample valve is closed to separate
the sample flow from the optical gas cell. Simultaneously, the flowback
solenoid valve is triggered to flow ~3 LPM zero air back to the heated
sample line.
The system zero check can be set to be operated automatically or manually
by operator via Thermo Modbus Controller (check zero) or PLC. By
triggering the system zero solenoid valve, a sufficient zero air flow (>6
LPM) is introduced into the sample probe via the heated umbilical, right
before the probe's primary filter. In this way, deviations in zero drift and/or
precision of the measuring system can be detected, recorded either by
system computer or data logger. Adjustments of the zero value by the
operator via a data logger, or maintenance of the measuring system (e.g. by
the supplier) may be necessary due to the results of the evaluation. When
performing a system zero check, all other control valves are in normal
sampling mode, and the output results are saved in "cons" file in the
directory of C:\cons or via data logger.
Zero air is generated from the system purge gas generator. All plumbing
work should be ready after system installation is complete. When doing a
system zero check, the user just needs to follow the auto procedure set by
the PLC to perform system daily zero check. To ensure a sufficient zero air
flow into the sample probe, it would be necessary to adjust the rotameter,
shown in
Figure
4–1.
Figure 4–1. Adjusting the Rotameter on the Pneumatic Panel
Thermo Fisher Scientific
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