Vaisala FD12P - Manual (Page 118)

User's Guide _______________________________________________________________________
118 _____________________________________________________ M210296en-A
Cleaning
Cleaning Lenses and Hoods
The lenses of the FD12P transmitter and receiver units must be
relatively clean to obtain reliable results. Dirty lenses give too high
visibility values. Clean the lenses every six months or more often
depending on the conditions (for example, if there are roads nearby).
Use the STA command for monitoring the system performance.
Usually, a data message is announced if there are some warnings.
Clean the lenses when the following warning appears:
BACKSCATTER INCREASED
To clean the lenses, do the following:
1. Moisten a soft, lint-free cloth with isopropanol alcohol and wipe
the lenses. Be careful not to scratch the lens surfaces. The lenses
should dry up indicating that the lens heating is functioning.
2. Check that the hoods and lenses are free of condensed water or
ice and snow deposits.
3. Wipe the dust from the inner and outer surfaces of the hoods.
4. After the optical surfaces are properly cleaned, type
CLEAN
↵ ↵↵ ↵
NOTE It is not necessary to give the CLEAN command always after the
cleaning. Choose the STA command and check only that the
BACKSCATTER CHANGE value of both the receiver and the
transmitter is close enough to zero (set to zero by the previous
CLEAN command).
Cleaning DRD12 Rain Detector
The Capacitive Rain Detector DRD12 should be cleaned every six
months or more often depending on the conditions.