Chapter 5: Using Your Freeze Dryer
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36
Original instructions
11.
Attach a pre-frozen sample to sample valve on drying chamber or manifold.
Note: If using a Clear Chamber, Tray Dryer or Heated Product Shelves, the
vacuum chamber must be fully vented (to atmospheric pressure) in order to
remove acrylic chamber or open door before loading sample into the drying
chamber.
Vacuum Pump Ballast Setting
Most vacuum pumps are equipped with a gas ballast mechanism. The freeze dry
process requires high vacuum. Therefore, it is recommended that the gas ballast be
closed during the operation of the Freeze Dryer. If the gas ballast is left open for
extended periods of operation, the oil can be pumped out the exhaust, causing the
pump to fail.
Purge Valve
The optional purge valve is installed between the Freeze Dryer collector chamber
and the vacuum pump. When the blue indicator bar is shown above the PURGE
button (on the Home screen), the purge valve is closed and the vacuum pump is
isolated from the Freeze Dryer collector chamber.
During Freeze Dryer start-up, the refrigeration system cools the collector coil
down to its working temperature. While the collector coil cools, the purge valve
can be closed and the vacuum pump allowed to run. This allows the vacuum pump
oil to heat up, which will evaporate and expel condensed solvents from the oil.
When the collector coil is at its working 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 Auto Start
Mode, the purge valve and vacuum pump will operate automatically to perform
this function. In Manual Mode the user must manually activate the purge valve
and vacuum pump to perform this function.
Before shut down the vacuum pump can be run for several minutes with the purge
valve 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 Auto Start Mode or Manual Mode, the user must manually
activate the purge valve and vacuum pump to perform this function at shut down.
If power to the Freeze Dryer is interrupted during the freeze dry process, the purge
valve will open during the power outage, and the vacuum bleed valve will open to
allow atmospheric air to enter the system.
Operating the Freeze Dryer
Auto start-up (without Purge Vale option)
1.
Go to Home screen
2.
Press AUTO, then press START
COLLECTOR will start immediately
