Christ ALPHA 1-2 LDplus - Separate Freezing and Drying of Liquids in Ampoules (Process B)

22 • Description of the Freeze Drying Processes Operating Manual Freeze Dryer ALPHA 1-2 LDplus
Caution:
The frozen samples can only be connected to the valves when a
pressure of less than 1.030 mbar is reached.
Liquids are frozen in flasks according to the shell freezing
principle, manually or with a turning device. Thanks to this freezing
process the layer thickness is reduced and the drying period is
considerably shortened.
Most of the manifolds and valves available allow a continuous
connection and removal of flasks during the drying process. Each
rubber valve is equipped with a closing and aeration valve.
If the rubber valves or stainless steel valves are stiff they must be
dismantled, cleaned, slightly greased with vacuum grease and
reassembled.
It is also possible to connect a distributor for 15 ampoules to every
rubber valve.
Using a distributor a maximum of 15 ampoules can be
simultaneously frozen in the cooling bath and connected to the
manifold.
3.4. Separate Freezing and Drying of Liquids in
Ampoules (Process B)
The refrigeration compressor and the vacuum pump are activated
via the control system to start the pre-freezing of the ice condenser
and the warming-up of the vacuum pump. The valve is closed
during warming-up of the pump. In case the unit is not equipped
with an electromagnetic pressure control valve we recommend to
use a manual stop valve. Without such a valve the vacuum pump
must not be warmed up.
The manifold is equipped with blind plugs for connection of a
maximum of 48 ampoules so that it can be pre-evacuated.
The first hose is clamped in the middle with the supplied hose
clamp and the blind plug is removed. The vacuum of the system is
preserved.
The liquid in the ampoule is either frozen under rotation in a
cooling bath or in a deep-freeze.
If shock-freezing is required we recommend that freezing is carried
out in liquid nitrogen or in a cooling bath.
The ampoule is then connected to the hose and the hose clamp is
removed. Thus the partial pressure in the ampoule is suddenly
decreased and a partial thawing during the evacuation process is
avoided.
One ampoule after the other is connected using this method.