Operating Manual Freeze Dryer ALPHA 1-2 LDplus General Information on Freeze Drying • 13
Freezing inside the unit is not necessary if the product is pre-
frozen or stored in e. g. a deep-freeze. In this case, especially
when freeze drying small quantities, it is advisable to pre-cool the
shelves in order to avoid partial thawing during the evacuation.
Possible water residue must be removed from the ice condenser
chamber. The drain valve is closed.
The ground-in stopper of the drying chamber must be greased with
high-vacuum grease!
The layer thickness of the product should not exceed 1 to 2 cm as
otherwise this has a negative effect on the duration of the drying
process.
2.4. Main Drying
The vacuum pump is switched on.
Please note:
Defrosting during the drying process is possible (visible foaming)
when drying products containing e. g. solvents or high salt
concentrations. In this case it is necessary to freeze the product at
temperatures as low as possible, e.g. in liquid nitrogen.
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