LI-COR LI7200RS, Инструкция по эксплуатации

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Section 2. Initial Setup
Tips for Success
The LI-7200/RS is very stable when the optics are kept clean. However, with con-
tinuous operation in dirty environments without cell cleaning, you may see mean
concentration changes of up to several percent or more. Properly cleaning the
optical bench and windows periodically will significantly reduce or eliminate such
changes. Use of the 2-micron Swagelok filters may help extend the cleaning inter-
vals.
Filtering
In situations where fine-particle filtering is required to maintain acceptable data
quality a restrictive single-micron filter can be used (LI-COR part number 9967-
008). The 7200-101 Flow Module was designed specifically for low-power operation,
and cannot be used with such filters. In these installations, an external pump will
be required.
Cleaning
Additional action is usually not required after cleaning. If possible, however, flow
dry, CO
2
-free gas through the cell and check the zeros. If they are not close, the
windows may need further cleaning, or the internal chemical bottles may need to
be replaced.
If you decide to recalibrate instead of cleaning, or cannot seem to clean the win-
dows sufficiently (and are sure the cause is not depleted chemical bottles) then you
should perform both zero and span. Contamination that causes a zero shift will
also usually cause a slight span shift too.
Vibrations
The LI-7200/RS is vibration sensitive to frequencies of 150 Hz ± the bandwidth.
Thus, if the bandwidth is 10 Hz, the frequency problem range is 140 to 160 Hz
(and upper harmonics). The instrument is completely insensitive to vibrations
slower than this, and very slightly sensitive at frequencies higher than this.
For land-based installations, the most likely source of vibrational problems would
be on a tower with tight guy wires. For other settings (aircraft, ships, etc.) where
there may be vibrations in the problem range, you should try to minimize the
2-16 LI-7200RS Enclosed CO₂/H₂O Analyzer