Section 4
4-4
Calibration
The H
2
O zero and span calibration is identical to that for CO
2
; however,
allow adequate time for equilibration (several minutes after changing the
humidity).
1.
Set the H
2
O reference to zero (FCT 68). If you are not using the
6262-03 Pressure Transducer, enter the barometric pressure in FCT 77.
2.
Display absolute H
2
O (FCT 32, 34, or 36).
3.
Flow a dry gas through both sides of the analyzer.
4.
Unlock the H
2
O zero potentiometer and adjust until the absolute H
2
O
concentration on the display reads zero.
5.
With a dry gas on the reference side, flow a span gas through the sample
cell. Set the span potentiometer to read the value of the span gas in the
appropriate units.
6.
Flow the span gas through both cells of the analyzer, at the same flow
rate. Set the H
2
O reference (FCT 68) to the value of the span gas in the
appropriate units. Display differential H
2
O (FCT 33, 35, or 37).
7.
There will likely be a small zero offset. Adjust the zero potentiometer to
read zero.
8.
To check the span, flow a different humidity through the sample cell.
FCT 32 (or 34 or 36) should show that value. Adjust the span as needed.
9.
Lock the potentiometers.
