METER GROUP AquaLab 4TE - Sample Temperature

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OPERATION
If a sample has a water activity of <0.03 a
w
, a < symbol in the Measurement tab indicates the
sample is too dry to be accurately measured by the AQUALAB (Figure1).
Figure1 Low water activity reading
If the measured a
w
appears lower than the known sample water activity, the instrument
sensors may have been contaminated and need to be cleaned or serviced (Section4.2).
2.2.2 SAMPLE TEMPERATURE
The ambient temperature of the AQUALAB should be between 15 and 50 °C. The AQUALAB
4TE and AQUALAB 4TEV have internal temperature control capabilities that enable them to
read samples at temperatures different from the ambient temperature, but no higher than
50 °C and no lower than 15 °C.
Samples that are more than 4 °C colder or warmer than the instrument chamber
temperature need to equilibrate to instrument temperature before taking a reading, ideally
within 1 or 2 °C of the chamber temperature. Rapid changes in temperature over short
periods of time causes the water activity readings to rise or fall until the temperature
stabilizes. Proceed with normal measurements when the temperature stabilizes within an
optimal 1 or 2 °C of the chamber temperature.
High water activity samples that are warmer than the chamber temperature can cause
condensation inside the measuring chamber, which adversely affects subsequent readings.
A warning message appears if the sample temperature is more than 4 °C above chamber
temperature (Figure2).
Figure2 Sample is too hot! message