Vaisala MM70 - Manual (Page 61)

Chapter 6 ___________________________________________________________ MAINTENANCE
CHAPTER 6
MAINTENANCE
Changing the Filter and Sensor
1. Screw out the filter from the probe head, see Figure 2 on page 11.
2. Remove the damaged sensor by pulling it out. Handle the sensor by the
plastic socket.
3. Insert a new sensor.
4. Make a humidity calibration.
5. Screw a new filter on the probe head, take care to tighten the filter
properly (5.1 Nm).
Cleaning the Sensor
Make sure to clean the sensor before calibration and storing the
MMP78 probe. For cleaning of the probe you need instrument air and
heptane liquid. Dry with instrument air to prevent oxidation of the
sensor. The oxidation of the sensor can cause extended response times
or drifting.
1. Blow the probe head (with filter) with instrument air to remove
the remains of the oil.
2. Immerse the probe head into heptane liquid and rinse out the oil.
Plastic
socket
3. Dry the probe head with instrument air. In case you are going to
calibrate the probe, remove the filter and dry the sensor with
instrument air. Check that the sensor looks clean.
VAISALA _______________________________________________________________________ 59