GE Moisture Image 1 Series Service Manual page 92

June 2003
B. Instructions for
Preparing Known
Samples
A-30
Note: This procedure is only for liquids that are highly miscible with
water. Excessive equilibrium times would be required with
less miscible liquids.
To prepare samples of known moisture content, use the apparatus in
Figure A-3 on page A-33 and complete the following steps:
1. Weigh the dry, empty apparatus.
2. Fill the glass bottle with the sample liquid.
3. Open both valves and turn on the magnetic stirrer.
4. While monitoring the dew point reading with the hygrometer,
bubble dry N through the liquid until the dew point stabilizes at
2
some minimum value.
5. Turn off the N supply and close both valves.
2
6. Weigh the apparatus, including the liquid, and calculate the
sample weight by subtracting the step 1 weight from this weight.
7. Insert a syringe through the rubber septum and add a known
weight of H O to the sample. Continue stirring until the water is
2
completely dissolved in the liquid.
8. Record the dew point indicated by the hygrometer and calculate
the moisture content as follows:
PPM
W
9. Repeat steps 6-8 until samples with several different moisture
contents have been analyzed.
Note: The accuracy of this technique can be checked at any point by
withdrawing a sample and performing a Karl Fischer
titration. Be aware that this will change the total liquid weight
in calculating the next point.
weight of water
------------------------------------------------- -
=
total weight of liquid
Application of the Hygrometer (900-901D1)
6
×
10