Chapter 6  ______________________________________________________________ Maintenance 
 
VAISALA _______________________________________________________________________ 83 
CHAPTER 6 
MAINTENANCE 
This chapter provides information needed in basic maintenance of the 
product. 
Periodic Maintenance 
PWD22/52 is calibrated at the factory and no initial calibration is 
required. 
Periodic maintenance of PWD22/52 includes: 
-  Cleaning the transmitter and receiver lenses and hoods. 
-  Cleaning the RAINCAP
®
 Rain Detector. 
-  Checking the visibility calibration and calibrating it, if necessary. 
-  Cleaning PWL111 lenses. 
   
PWD22/52 is designed to operate continuously for several years without 
other maintenance than cleaning of the lenses and the RAINCAP
®
 
sensing surface. 
Before any commands can be given to PWD22/52, open the 
communication line by typing the following: 
OPEN 
PWD22/52 answers as follows:  
LINE OPENED FOR THE OPERATOR 
To release the line to automatic messages, use the CLOSE command. For 
details, see Chapter 5, Operation on page 49.