Pawkit
Operation
20
If these standards are not available you can make a
saturated Sodium Chloride (NaCl) slurry with a
water activity value of 0.75
a
w
. To make a salt slurry
of NaCl add water until the salt can absorb no more
water, as evidenced by the presence of free liquid.
The slurry should take the shape of the cup and
flow when tipped with the amount of free liquid at
a minimum.
Steps in Calibration
1. Take a vial of the 0.760
a
w
NaCl standard and
empty the entire contents of the vial into a sam-
ple cup. Place the sample cup into the Pawkit,
and close the chamber.
2. Press the left button (
I
) to take a reading. If it is
reading the correct water activity ±0.02, your
Pawkit needs no calibration. If not take a second
reading. After the second reading, note the
water activity value shown. If it is reading the
correct water activity ±0.02, your Pawkit needs
no calibration. If it is not reading correctly, pro-
ceed to the next step.
3. Once the reading is finished, the right button
(
II
) will be active. Button
II
is only active until
