AquaLab
7. Veri cation and Calibration
37
7. Veri cation and Calibration
It is important to verify AquaLab’s water activity calibration against
known standards to guarantee optimal performance and accuracy.
Decagon recommends veri cation daily, once per shift or before
each use.
Water Activity Veri cation
AquaLab uses the chilled-mirror dewpoint technique to determine
water activity. Because this is a primary measurement of relative hu-
midity, no calibration is necessary; however, it is important to verify
for linear o set periodically. e components used by the instru-
ment to measure water activity are subject to contamination which
may a ect the AquaLab’s performance. When this occurs, it changes
the accuracy of the instrument. is is what is called a “linear o set.”
erefore, frequent veri cation assures you that your AquaLab is
performing correctly. Linear o set is checked by using two di erent
veri cation standards.
Veri cation Standards
Veri cation standards are specially prepared unsatuarated salt solu-
tions having a speci c molality and water activity value which are
accurately measurable. e veri cation standards that were sent with
your initial shipment are very accurate and readily available from
Decagon. Using veri cation standards to verify accuracy can greatly
reduce preparation errors. For these reasons, we recommend using
standards available through Decagon for the most accurate veri ca-
tion of your AquaLab’s performance.
Performance Veri cation Standards come in ve water activity lev-
els: 1.000, 0.984, 0.760, 0.500, and 0.250 a
w
. e standards are
To Next Page
Loading...
