User's Guide ______________________________________________________________________
44 __________________________________________________________________ M210934EN-B
Equipment needed:
- Apparatus for determining water content ( for example, coulometric
titrator and e.g. magnetic stirrer.)
- Oil test station:
- a temperature test chamber
- for example, a conical flask (1L) sealed by PTFE stopper
with an inlet for a moisture probe
- MMT162 by Vaisala
- magnetic
stirrer.
Procedure:
1.
Define the water content of the oil sample with the titration. Use
the oil moisture level that is close to real conditions in the process.
2.
Measure the water activity of this sample with MMT162 at two
temperatures that differ at least 20 °C. Follow the measurement
stabilization illustrated by the graph.
NOTE
The sample has to be sealed very carefully i.e. not to be in contact
with ambient air, which would change the water content.
NOTE
If the oil sample is very dry and the temperatures are close to each
other, it may cause inaccuracy to the calculation model. In order to
get the best possible performance it is recommended to use oil
conditions that represent real conditions in application.
Recommended values for sample are aw approx. 0.5 at 20 °C.
3.
Define the correlation between aw, T and PPM (w/w) from the
measured values. Calculate A and B according to the following
example.
[ ]
[ ]
( ) ( )
1
/
1
-
2
/
1
1
(
-
2
(
T
T
T
PPM
LOG
T
PPM
LOG
A
sat
sat
)
)
=
[ ]
)
(
A/T1
-
1
T
PPM
LOG
B
sat
=
