CS IRGASON, Instruction Manual, Page: 41 / 74

IRGASON
®
Integrated CO
2
/H
2
O Open-Path Gas Analyzer and 3D Sonic Anemometer
29
The first part of the following procedure simply measures the CO
2
and H
2
O
zero and span, without making adjustments. This allows the CO
2
and H
2
O gain
factors to be calculated. These gain factors quantify the state of the analyzer
before the zero-and-span procedure, and in theory could be used to correct
recent measurements for drift. The last part of the zero-and-span procedure
adjusts internal processing parameters to correct subsequent measurements.
If the zero-and-span procedure is being performed off-site (e.g., in a lab), be
sure to mount the IRGASON on the lab stand (pn 27278). This will ensure the
analyzer is in the correct upright orientation and has the correct optical
alignment.
It is imperative that the zero-and-span procedure be done correctly and not
rushed; allocate plenty of time for the procedure (at least an hour).
Resting the analyzer on its side during the zero-and-span
procedure may result in measurement inaccuracy.
To check and then set the IRGASON zero and span, follow the steps below:
1. Remove power from the EC100.
2. If not already done, clean the windows and snouts with alcohol and a non-
scratching tissue or cloth.
Make sure the alcohol and any residual water completely
evaporate from the analyzer before proceeding with the
zero-and-span procedure.
3. As shown in FIGURE 9-4 , position the IRGASON zero-and-span shroud
(pn 26390) over the upper and lower snouts. To do this, twist the two ends
of the shroud together to minimize the length of the shroud. Make sure the
rubber seals on the ends of the shroud are clean and in good condition.
Position one end of the shroud over the lower snout and twist the top part
of the shroud, allowing it to extend and cover the upper snout; while doing
so, avoid making contact with the sonic transducers. Continue twisting the
shroud until it is fully extended and covering both snouts. Twist the shroud
so that the gas tubes and temperature thermistor cable are directed towards
the back of the sensor. Hang the tubes and cable over the trunk of the
sensor to alleviate any strain on the optical arms. See FIGURE 9-4 , The
zero-and-span shroud mounted on the zero-and-span stand
.
CAUTION
CAUTION