Martin Christ Alpha 2-4 LDplus - Manual (Page 27)

Operating Manual Freeze Dryer ALPHA 1-4 LDplus / ALPHA 2-4 LDplus Description of the Freeze-drying Processes 27
3.3. Separate Freezing and Drying of Liquids in
Flasks (Process B)
Possible water residue is removed from the ice condenser
chamber. The drain valve is opened so that the water residue can
drain off. The ice condenser chamber should be wiped out if
necessary.
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.
Several manifolds and mountable drying chambers with several
connections for rubber valves are available for the drying process
outside the ice condenser chamber (see accessories catalogue).
The drying chamber with connections for rubber valves is mounted
directly to the sealing ring of the base plate. Manifolds with outer
ground joints NS 45/40 are connected via the ground-in socket of
the acrylic lid.
In order to ensure a vacuum-tight connection and to simplify the
removal of the named accessories the ground-in surface must be
slightly greased with vacuum grease before use. The manifold or
drying chamber is mounted afterwards and turned by 360° for an
even distribution of the grease.
The ground-in surfaces have to be cleaned and greased before
every further mounting of accessories.
Before the drying process can start it is necessary to check that all
valves are closed.
To start the drying process, the main drying process has to be
activated in the control system. The pressure control valve opens
and the main drying process starts.
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.