Section 2
Setup & Operation
2-5
Replace the filters when flow rates drop due to particle retention, or when
the apparent LI-6262 response to changes in humidity becomes slow due to
filter retention of hygroscopic material.
When using the LI-6262 in high flow rate applications (e.g. eddy correlation)
or where sample air is particularly dirty, you may consider stacking two
filters in series. For maintenance, replace the filter furthest upstream from
the analyzer with the filter closest to the analyzer and replace the filter
closest to the analyzer with a new filter.
µ
Par
t # 99
67-008
IN
1
µ
mP
TF
E
IN
Air In
Air Out
Install the new filter(s) with the blue lettering facing
away from
the
SAMPLE IN
or
REFERENCE IN
ports.
Instruments with serial numbers of IRG3-239 and below were shipped with
internal Balston filters. Balston filters have good particle retention with low
flow resistance, but they equilibrate slowly with changing humidities, thus
degrading the apparent response time and performance of the LI-6262.
Replace the Balston filters with external Gelman filters as described above.
We recommend that the
SAMPLE IN
and
REFERENCE IN
ports be covered
with the dust caps provided or attached to an airline when the instrument is
not in use. This will prevent dust from entering the instrument downstream
from the filters where it can enter the optical paths.
Replacement Gelman Acro 50 filters can be obtained from LI-COR (part #
9967-008).
2.4 Absolute vs. Differential Mode Operation
The LI-6262 may be operated in either absolute or differential modes to
simultaneously measure CO
2
and H
2
O in any units. The following
discussion will help you to set up the analyzer to measure these outputs.
