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Product Service: Domestic 1-800-522-7658, International 816-333-8811
Chapter 4: Using Your Freeze Dryer
Purge Valve
The optional purge valves are installed between the
Freeze Dryer collection chamber and the vacuum
pump. When the green LED above the PURGE
switch is illuminated, the purge valves are closed
and the vacuum pump is isolated from the Freeze
Dryer collection chamber.
During Freeze Dryer start-up, the refrigeration
system pulls the collector coil down to
temperature. While the collector coil cools, the
purge valves can be closed and the vacuum pump
allowed to run. This allows the vacuum pump oil
to warm which will evaporate and expel condensed
solvents from the oil. When the collector coil is
down to temperature and the freeze dry process is
started, the warm pump oil is less likely to
condense solvent vapors that are not trapped by the
collector coil. When the Freeze Dryer is operated
in the Automatic Mode, the purge valve and
vacuum pump will operate automatically to
perform this function. In the Manual Mode the
user must manually activate the purge valve and
vacuum pump to perform this function.
During shut down the vacuum pump can be run for
several minutes with the purge valves closed. This
will allow the warm pump oil to evaporate and
expel solvent vapors that condensed in the pump
oil during the freeze dry process. Whether the
Freeze Dryer is run in the Automatic Mode or the
Manual Mode, the user must manually activate the
purge valve and vacuum pump to perform this
function.
If power to the Freeze Dryer is interrupted during
the freeze dry process, the purge valves will close
during the power outage. This will prevent the
pump oil from back streaming out of the vacuum
pump into the Freeze Dryer.
