39
AQUALAB TDL/TDL 2
6. The readings may lead to one of three outcomes.
a. If the AQUALAB TDL reads within ±0.005
a
w
of the first verification standard, take
two readings of the second verification standard. The second water activity reading
for the second verification standard should be within ±0.005
a
w
.
b. If either verification standard is not correct, it is probably due to contamination
of the sensor chamber. Clean and air out the chamber (
) and repeat
verification from
.
c. If readings are consistently outside the water activity of the first verification
standard by more than ±0.005
a
w
, a linear offset can be applied. Adjust the reading
to match the correct verification standard value (
).
Measure verification standard
Clean sample
chamber
Reread first
standard
Go to offset
procedure
Go to sampling
procedure
Read second
standard
Clean sample
chamber
Repeat process
Figure 47 Verification standard flowchart. A check indicates AQUALAB TDL verified the standard
within specification; a cross indicates AQUALAB TDL did not verify the standard within specifications.
4.1.2 LINEAR OFFSET
After verification and cleaning the instrument, an offset may be necessary.
NOTE: A linear offset does not adjust the calibration for all water activity levels and should only be used if measuring
water activity in a very small range.
1. Navigate to the Configuration tab.
2. Select
Calibration
.
3. Select
Water Activity
.
4. Select
Start
(
).
