Diagnostics
CIRAS-2 Operator's Manual Version 2.04
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Analyser Temperature (
o
C)
Should be set to approximately 55
o
C. The analyzers are thermostatted and controlled to approximately
55
o
C.
Atmospheric Pressure (mb)
Absolute pressure in the Reference cell. This should correspond closely to the local atmospheric
pressure in mb (Altitude dependent). At sea level, you should expect between 950-1050 mb. This value
decreases approx. 1mb/10m increase in altitude.
Pressure Difference (mb)
Differential pressure between the reference and analysis cells. The mid-point is approximately 25 mb.
Excessive differences indicate blockages or pressurisation of the analyzer.
Stored Zeros
Zero values stored by CIRAS-2 after 30 minutes running. The CIRAS-2 checks the values for changes in
the values to warn of zero column exhaustion or deterioration of analyzer performance.
Reset Stored Zeros
Clears the stored zeros. If the zero reads are outside the normal range (normally due to exhausted
chemicals in the zero columns), then, after replacing the absorbers, click on this to reset the stored zeros.
This will stop further error messages.
CO
2
Reference
A/D reads for the CO
2
Reference Cell. Values depend on valve selection (see Valve Settings below).
CO
2
Analysis
A/D reads for the CO
2
Analysis Cell. Values depend on valve selection (see Valve Settings below).
H
2
O Reference
A/D reads for the H
2
O Reference Cell. Values depend on valve selection (see Valve Settings below).
H
2
O Analysis
A/D reads for the H
2
O Analysis Cell. Values depend on valve selection (see Valve Settings below).
Please note: CIRAS-2 always starts Diagnostics in the ZERO mode (with Cuvette set to Manual
Cuvette).
Valve Settings
Apply valves to Zero
Click on this to put CIRAS-2 into Zero Mode. Without CO
2
and H
2
O in the sample cell, IR absorption is at
a minimum level so the detector outputs are at their maximum. The A/D reads for both CO
2
and H
2
O
(Reference & Analysis) should typically be >45000 and stable.