User's Guide _______________________________________________________________________ 
54  ___________________________________________________________________ M210865EN-H 
CHAPTER 6 
MAINTENANCE 
This chapter provides information on the maintenance of Dewpoint 
Transmitter DMT152. 
Cleaning the Transmitter 
The body of the transmitter can be cleaned by wiping with a moistened 
lint-free cloth. Do not immerse the transmitter in liquid and do not use 
cleaning agents or solvents. Do not attempt to clean the filter or the 
sensor element. If the filter is contaminated, replace it with a new one. 
Changing the Filter 
If the filter is contaminated, it should be replaced. New filters can be 
ordered from Vaisala, with the order code 220957. Be careful when 
changing the filter, since it is easy to break the sensor when the filter is 
removed. 
CAUTION 
installed in a pressurized chamber, always make sure 
that the pressure of the chamber is equalized with the ambient pressure 
prior to removing the transmitter. When the transmitter is removed for 
maintenance, cap the hole with a capped nut. This way, the p
rocess can 
be running although the transmitter is not in place.
 
Plugs are available from Vaisala for ISO threaded connections (Vaisala 
order code 218773) and NPT threaded connections 
 
(Vaisala order code 222507).
 
 
When replacing the filter, note the following: 
-  The pores of the steel mesh may become blocked if touched. Do not 
touch the filtering surface with your hands or any tools. Always 
handle the filter from the top of the filter body. 
-  Touching the filter with your fingers will also deposit oil and dirt on 
the filter, which may affect the measurement. Always handle the filter 
with gloved hands. 
-  When installing the transmitter after a filter change, always use a new 
sealing ring (ISO and UNF threads only).