METER GROUP AquaLab 4TE - Buttons

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SYSTEM
thermocouple attached to the mirror then records the temperature at which condensation
occurs. The AQUALAB then signals with beeps and displays the final water activity and
temperature.
The AQUALAB uses an internal fan to circulate the air within the sample chamber to
reduce equilibrium time. Since the AQUALAB measures both dew point and sample surface
temperatures simultaneously, it eliminates the need for complete thermal equilibrium,
thereby reducing measurement times to <5 min for most samples.
Additionally, the AQUALAB 4TEV uses a capacitance humidity sensor to measure the water
activity of a sample. The sensor is suspended in the headspace of the chamber and uses
a special polymer material sandwiched between two microporous electrodes to sense
humidity changes. The sensor measures a specific capacitance, which is translated by
the software and displayed as water activity on the instrument screen. At equilibrium, the
relative humidity of the air in the chamber is the same as the water activity of the sample.
Mirror
Thermopile
Photoelectric (optical)
sensor
Sample block
Fan
Latch
Capacitance sensor
filter (TEV only)
Top block
O-ring
Lever
Figure31 Sample chamber interior
3.2.3 BUTTONS
The power switch is located on the lower left corner of the AQUALAB back panel. After
being turned on, the AQUALAB should warm up for 15 minutes before operation to ensure
accuratereadings.