Section 4
4-4
Calibration
9.
Note the reference dew point value
Watch the left hand (reference) Td_C value. It will likely drop a bit,
as the still unequilibrated air from the sample cell enters the reference
cell. When it stabilizes (30 seconds), set the sample IRGA to read
that value.
10.
Quit and Save, if done
Press
escape
, and select "View, Store Zeros & Spans" now, if you
are done calibrating.
Calibrating the LI-7000 CO
2
/H
2
O Infrared Gas Analyzer
Preliminary
To avoid condensation problems choose a dew point temperature that is
about 3 to 5 °C below the ambient temperature. Also, since water vapor
sorbs and desorbs from surfaces, allow plenty of time for the reading to
stabilize, and minimize the surface area it has to absorb on (minimize
tubing lengths). It is important not to rush through water vapor
calibrations; give the surfaces plenty of time to equilibrate to large
changes.
The LI-7000 provides two convenient user interfaces for doing user
calibrations (Figures 4-2 and 4-3).
More...
Edit...
CO2A
µ
m/m
CO2B
µ
m/m
H2OAmm/m
H2OBmm/m
Done
User Calibration
13.1
1
5.23
2.234
4.387
CO2 Action: [
<Do Nothing>
]
H2O Action: [ <Do Nothing> ]
Figure 4-2. LI-7000 calibration function on instrument display.
