Campbell Scientific EC155 CO2 and H2O Closed-Path Gas Analyzer and EC100 Electronics with Optional CSAT3A 3D Sonic Anemometer - Manual (Page 44)

EC155 CO
2
and H
2
O Closed-Path Gas Analyzer
FIGURE 9-6. ECMon Zero/Span window
l. Enter the known concentration of CO
2
(in ppm) in the Span
Concentration box and press Span. This will cause the analyzer to adjust
the value of its CO
2
Span parameter, forcing the measured CO
2
concentration to the value specified. Verify the CO
2
concentration reads
the correct value.
m. Replace the CO
2
span gas with an H
2
O span gas of known dew point.
Allow the gas to flow through the sample cell; as before, higher flows may
be desired for a couple minutes to more quickly establish equilibrium
before resuming a flow between 0.2 and 0.4 L/min. Wait for the readings
to stabilize.
n. Enter the known dew point (in °C) in the Span Dew Point box and press
Span. This will cause the analyzer to adjust the value of its H
2
O Span
parameter, forcing the measured dew point to the value specified. Verify
the dew point reads the correct value.
o. The zero-and-span procedure is now complete.
9.5 Replacing the EC155 Desiccant/CO
2
Scrubber Bottles
If more than one year has passed since replacing the desiccant/scrubber, or if
zero-and-span readings have drifted excessively (see Section 9.4, Zero and
Span above), the desiccant/scrubber bottles (pn 26511) within the EC155
analyzer head should be replaced as follows:
a. Remove the analyzer in the same way as explained in Section 9.3,
Cleaning Analyzer Windows of this manual.
34