Chapter 3 ______________________________________________________ Functional Description
VAISALA _______________________________________________________________________ 21
Sensor Warming in High Humidities
DPT146 transmitter has a warming feature which prevents the sensor and
filter from becoming wet in high humidities. High humidity may be
present when the dewpoint temperature rises close to the gas temperature.
Sensor warming is switched on automatically when the humidity in the
measured gas increases to a level where dew can start to form. The
advantage of sensor warming is the rapid response of dewpoint
measurement. A wet sensor and filter would otherwise result in a
dewpoint equal to ambient temperature (that is RH = 100 %).
If in spite of sensor warming the sensor gets soaked, it will recover fully
back to normal operation after it dries out.
NOTE
Sensor warming is not available if the transmitter has been ordered with
RS-485 only output.
BAROCAP® Technology
The BAROCAP® silicon capacitive absolute pressure sensor was
developed by Vaisala for barometric pressure measurement applications.
The BAROCAP® sensor has excellent hysteresis and repeatability
characteristics, low temperature dependence, and a very good long-term
stability. The ruggedness of the BAROCAP® sensor is outstanding and
the sensor is resistant to mechanical and thermal shocks. The pressure
measurement of the MPS1 multiparameter sensor is based on an
advanced RC oscillator and reference capacitors against which the
capacitive pressure sensor is continuously measured. The microprocessor
of the transmitter performs compensation for pressure linearity and
temperature dependence.
