BUCHI Extraction System B-811 LSV - Manual (Page 21)

4 Description of function
21 B-811 Operation Manual, Version G
4 .3 .3 Drying
After the rinsing process is completed, the glass valve closes while the lower heating
is activated again. The solvent recovery is carried out. The solvent is evaporated,
condensed at the condenser, and collected in the extraction chamber. At the end of
drying the entire solvent is evaporated and collected in the extraction chamber to be
eventually re-used.
Fig. 4.5: Drying
4 .4 The three steps in detail
4 .4 .1 Extraction - Step 1
The extraction process takes place in step 1. The sample is placed into the glass sample tube or
thimble. The solvent is added from the top of the condenser or directly into the beaker. The extraction
procedure depends on the selected extraction method. One of the four possible extraction methods is
applied:
Soxhlet Standard
The method “Soxhlet Standard” follows a real Soxhlet extraction known from the glass apparatus.
The solvent is heated up by the lower heating element and evaporated. The upper heating element •
is deactivated. The vapour rises up to the condenser. The condensed solvent flows down along the
condensation tube into the extraction chamber with the sample inside. The condensed solvent is
collected in the extraction chamber while the glass valve is closed. The sample is extracted.
The solvent level rises up to the optical sensor.
•
Each time the solvent level reaches the optical sensor, the solvent containing the extracted •
compounds is released into the beaker by opening the magnetic valve. The glass valve remains
open, until the extraction chamber is empty. One cycle is finished.
The number of cycles and/or time defines the length of the extraction process. If the programmed
number of cycles is reached and/or the extraction time is up, all valves are opened and the solvent is
released into the beaker. Then the program switches to the next step.