Vaisala DM500 - Manual (Page 115)

Chapter 18 _____________________________________________________________ Maintenance
VAISALA ______________________________________________________________________ 113
CHAPTER 18
MAINTENANCE
This chapter provides information that is needed in basic maintenance
of the product.
Cleaning the Sensor
Clean the sensor whenever the system gives a warning of
contamination on the sensor. Cleaning is also strongly recommended
before calibration and adjustment or when there is a reason to believe
that the measurement is unstable or the offset has increased.
Contamination typically causes a positive offset to the measured
dewpoint when there is a liquid phase on the sensor. When measuring
frostpoints, the instability of the measured value increases if the
sensor is dirty, but usually there is no offset.
The sensor is robust and constructed of hard materials. Thus even
frequent periodic cleaning of the sensor can be done without any
concern of sensor wear down.