Vaisala DMT152 - Manual (Page 57)

Chapter 6 _______________________________________________________________ Maintenance
VAISALA ________________________________________________________________________ 55
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 If the transmitter is 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 process 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).