BUCHI SpeedExtractor E-916 - Manual (Page 45)

6 Operation
45 SpeedExtractor E-916/E-914 Operation Manual, Version D
If the leak test shows that the SpeedExtractor is not tight, check the following options.
One or more positions have a lower pressure than the others:
• The drain valve is open  close the valve (see section 8.1.3)
• The cup seals (bottom or top) are not tight anymore. The seals can be used for at least 100 ex-
tractions, if not damaged mechanically by sand, sample, etc.  check visually, replace the faulty
one (see section 7.2.2). If no damage can be seen due to a micro tear replace the bottom and top
seal and repeat the leak test.
The overall pressure is too high:
• The position valve might be defective. It is recommended to verify this hypothesis by re-do a leak
test, with only 2 positions activated. Choose therefor a position with the same or with a pressure
close to the overall pressure, and a position with a significantly higher pressure. This second leak
test helps to identify the faulty valve.  For exchange of a defective position valve, please contact
BUCHI Service.
• The check valves of the pump are clogged due to impurities  clean the check valves (see sec-
tion 8.1.5)
NOTE
Often a pressure increase of up to 10 bar or more is observed in the hold step. This is because the
solvent and the cell are not heated up to the set temperature. In order to get good reproducible
results, it is therefore advisable to perform a leak test twice.
It is always possible to switch to the STATUS view dur-
ing the leak test if the different stages of the process
are of any interest.
6.2.6 Flushing the instrument
NOTE
When using analytes with low detection limits, the instrument must be flushed thoroughly for 2 min
with a suitable organic solvent to avoid carryover before the next extraction run.
When changing the solvent from one run to another it is
recommended that the lines be flushed with the solvent
used for the subsequent extraction. You can either flush
the solvent in the collection vials or the waste bottle. For
the latter the lines from the outlet valve to the collection
bottle are not flushed. However, placing the extraction
cells in the heating block is always mandatory. Flushing
with empty positions is impossible as the presence of
the cells is checked during the flush procedure. Parameters E-916 E-914
Flush with solvent 120 s 180 s
Flow rate 50 mL/min 50 mL/min
Flush with gas 180 s 240 s
NOTE
Always use empty extraction cells to flush the system. Changing the solvent while the extraction cell
is filled, can result in extraction and hence contamination of the lines with matrix constituents.
In contrast to flushing during extraction (see section 6.4.2), the flow rate is not reduced in the FLUSH