Technical data

2.6. End of drying and aeration
A rough indication of the end of drying is the vacuum and the ice
condenser temperature. The ice condenser is no longer loaded
and reaches the final temperature of approx. -55°C to
-85°C. The pressure in the drying chamber decreases according to
the ice condenser temperature.
The end of the drying process is reached when the temperature of
the product and that of the shelves are about 15 to 20°C. At the
same time, both temperatures should not deviate by more than 5 K
from each other.
The vacuum pump is switched off and the drying chamber is
aerated via a rubber valve or the aeration valve. The aeration
valve can also be used to “flood” the unit with nitrogen or another
inert gas instead of using air.
Then the unit is switched off and the product is removed.
2.7. Defrosting
Defrosting of the ice condenser is carried out at room temperature
or with warm water. At a maximum the ice condenser chamber
may be half filled with water.
When defrosting the ice condenser with (warm) water, it is of
crucial importance that no water gets into the pipe connection for
the vacuum pump and the vacuum sensor (see figure)!
The condensate as well as the defrosting water is drained through
the drain valve at the left side of the unit. To do this, a hose is put
onto the nozzle. The condensate and the defrosting water are
collected in a vessel.
Max. liquid height
Connection pipe for vacuum pump
Connection pipe for vacuum sensor
18 • General Information on Freeze Drying Operating Manual Freeze Dryer ALPHA 1-4 LSC / ALPHA 2-4 LSC