V S A Q u i c k S t a r t G u i d e
2. AquaLab VSA Performance Verification overview—
• AquaLab VSA performance and cleanliness should be
checked frequently; before each isotherm test is
recommended.
• Press until you are at the Measurement screen (2nd tab).
• Use AquaLab Verification Standards to verify performance
or adjust linear offset.
• To verify, remove weigh pan and then place sample cup
containing one of AquaLab’s verification standards in
sample chamber. Close lid and carefully avoid spillage; See
Figure 5: Sample Chamber.
• Move latch left and/or press to start a reading. The
pinwheel will spin indicating a measurement is running.
The
a
w
reading for the standard and the temperature
will display when finished. Make sure the
a
w
reading
on the standard is /-0.005 of the correct
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w
for the
standard. (+/- 0.02 if cap sensor is used)
• If an offset adjustment is needed, refer to chapter 7 in the
user’s manual.
Figu
re 5: Sample chamber
Lid
Base
V S A Q u i c k S t a r t G u i d e
3. Sample Preparation—
• Fill sample cup no more than half full (~7ml).
Do Not Overfill!
• Minimum sample amount should cover bottom of sample
cup (500-2000 mg) (small gaps OK).
• Ensure rim and outside of sample cup are clean.
• Make sure sample temperature is not more than 4°C above
chamber temperature.
4. Starting a Test—
• Before starting a test, set the Volatiles: Yes/No option in
the configuration menu. If your sample has volatiles,
select “Yes” otherwise select “No”.
• On the main screen, select the test wizard .
• Provide a name for the test using the arrow keys and then
press . (The name of a previous test will appear by
default.)
• Enter initial moisture content if known (optional). Press
to continue or to go back.
• Setup each stage of the isotherm test. A stage is used to
adjust the isotherm settings for an individual sample (up to
20 stages). Each stage is setup with the isotherm method
(DDI or DVS) and the settings for that portion of the
isotherm. Once a stage is created, it can be modified or
deleted anytime before the test is started.
i.e. For milk powder, Stage 1 could use the DDI method to
ramp quickly from 0.1 to 0.4
a
w
and Stage 2 could use
the DVS method to step from 0.4 to 0.8
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w
slowly in
0.05
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w
increments.
• To setup a new stage, select “new” and press . A screen
with several parameters will appear. If a previous test
has been run, the stages for that test will be listed by
default. These stages can be used as is or updated with
new settings. If you need to delete a stage, go to the
specific stage and press . Scroll down to the bottom of
