Buchi SpeedExtractor E-914, Operation Manual

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8 Troubleshooting
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SpeedExtractor E-916 / E-916XL / E-914 Operation Manual
Replacement of seals
A damaged seal manifests itself in the form of pressure fluctua-
tions, and drops of solvent begin to appear below the opening
of the backwash head. Replacement of the seal is the same in
both pumping blocks.
• Carefully remove the purging head.
• Remove the defective seal with a blunt object or by hand.
• Insert the new seal and carefully put the purging head on the
piston.
• Put the pumping head on the piston. Tighten the four nuts on
the pumping head. Be careful of the orientation of pumping
head; the outlet check valve must face upward.
Fit the capillaries and tubing in the reverse order as in disassem-
bly.
Proceed according to the section “Replacement of outlet and
inlet check valves” and check whether all connections are leak
free under operating pressure.
8.1.6 Precipitation in the outlet lines
Some samples are prone to be precipitated upon passing through the cooling unit during the dis-
charge step. To identify possibly clogged lines, perform a flow test (see section 8.2.4). When the
relative back pressures of the line exceed 10 bar, the line is either contaminated with sample or par-
ticles of the septa (see sections 7.2.3 and 7.2.4) or are deformed. Check the needles first and clean or
replace them if necessary (see section 7.2.3).
Try to clean the lines by flushing them thoroughly with a suitable hot organic solvent heated up in the
extraction cells. To do so run an extraction process with empty extraction cells (with high tempera-
tures, high pressure and long hold time, see section 8.1.3). If the solvents in the collection vials during
a new flushing procedure is still differing considerably, the lines are most probably still contaminated
with residues or deformed. In this case, the lines from the heating block to the collection tray, including
the cooling unit, need to be replaced by a service technician.
For samples which are prone to be precipitated from the extract solution, setting the hold time of the
first cycle to 0 min often eliminates the problem. Alternatively, there is a shorter cooling unit available
which does not cool down the sample that much and hence reduces the risk of precipitation. The
alternative cooling unit (P/N 053682) must be installed by a BUCHI approved service technician. Please
refer to your local dealer or BUCHI customer service.