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SYSTEM
3.2 COMPONENTS
This section describes the components associated with the AQUALAB3 system.
3.2.1 SENSOR BLOCK
The AQUALAB 3 has been designed around a modular sensor block assembly. This allows
the sensor block to be easily replaced—greatly reducing or even eliminating downtime due
to annual factory calibration. The sensor block is easily removed from the main instrument
chassis by loosening the two thumb screws and removing the ribbon cable. This allows the
sensor block to be cleaned (Section4.2).
The AQUALAB 3 sensor block contains both a chilled-mirror dew point sensor and a
capacitance hygrometer. The chilled-mirror sensor measures the water activity of the
equilibrated chamber by cooling the mirror surface until water begins to condense. This is
known as the dew point temperature and is a direct measurement of the water activity in
the head space. The capacitance hygrometer consists of a hygroscopic porous electrolytic
polymer. As water is absorbed, the capacitance of the sensor changes.
Sensor
block
Ribbon
cable
Side tabs
Thumb
screws
AQUALAB 3
with lid removed
Figure84 Sensor block in AQUALAB 3