Grant Instruments
30641 V1.3
Yoyolog
Page 33
Operating Manual
Important notes for measuring humidity
The Yoyo humidity/temperature probes are a precise, reliable humidity sensor
element which has a good long-term stability. The capacitive sensor allows for
humidity measurement in many applications and will give stable readings in clean
environments for several years.
Depending on the environmental conditions the sensor can become contaminated
by for example: dust, chemicals and dirty water which will reduce the active life.
There are further limitations, the sensor may be used in a operating range of
0-100% RH this operating range is reduced at as the operating temperature
increases. See the graph below. This is due to the fact that quite an aggressive
environment is developed when measuring high humidity and high temperature at
the same time:
The sensor should not be damaged when condensation occurs occasionally. If
condensation does occur, dry out the sensor in order to return to the correct
measurements, except the sensor polymer is contaminated with substances (see
above).
If condensation occurs regularly or for a long period of time, the sensor life is
reduced. If the sensor is even saturated it may give incorrect readings in the range
of 0-100% RH (sometimes even negative readings), but will recover when water
droplets have evaporated.
To ensure high quality readings we therefore recommend that probes/loggers are
verified and calibrated on an annual basis.
Operating conditions
-- -- Normal/Range
-- -- Max. Range
Humidity
Temperature
