LI-COR LI7200RS, Instruction Manual

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Cleaning the Optical Path
Important: Power off the gas analyzer (disable the power supply or disconnect
the power cable from the LI-7550) before conducting any maintenance that
involves disassembly or disconnecting cables. Disassembling the instrument or
detaching or attaching head cables while the instrument is powered on may dam-
age the instrument or result in a loss of data.
The LI-7200/RS windows should be kept clean through regular maintenance. The
analyzer is specifically designed to make it easy to remove and clean the cell
without the use of tools.
When operating without an intake filter, the cleaning frequency is highly depend-
ent upon the air quality in the environment. In clean-air environments, the fre-
quency of cleaning may be as low as several months. In environments or periods
with high amounts of salts, pollen or dust, the frequency may be as high as every
one to two weeks.
Important: The LI-7200/RS detector is not affected by UV radiation when the
optical path is open. The original LI-7200 detector, however, is affected by UV
radiation. Exposure to direct sunlight temporarily reduces the sensitivity of the
detector across all wavelengths, but it will not affect readings from the analyzer
in most cases. If you are using an original LI-7200, it is important to cover the
upper window with an opaque cloth or your hand when the optical path is open.
If the optical path is exposed to sunlight it may take several weeks for the
detector to recover. Let the instrument sit unpowered for 3 to 4 days to shorten
the recovery time.
Opening the Optical Bench
Loosen the two knurled knobs on the top of the LI-7200/RS sensor head, and then
pull the top of the sensor head out away from the optical bench (
Figure 5-1 on the
next page). There are cleaning swabs in the spare parts kit under part number 610-
05315.
The windows are sapphire, and are extremely durable and resistant to scratches.
Clean them with a mild detergent or glass cleaner and a soft, lint-free cloth.
Section 5. Maintenance
5-3 Cleaning the Optical Path