Martin Christ Beta 2-8 LDplus - Manual (Page 30)

30 Description of the Freeze-drying Processes Operating Manual Freeze Dryer BETA 1-8 LDplus / BETA 2-8 LDplus
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.
Sealing of the ampoule is carried out in the same way. The hose of
the ampoule to be sealed is clamped and the ampoule is sealed
under vacuum using the blow lamp.
If the ampoule breaks during sealing the vacuum in the drying
chamber is not affected due to the clamping with the hose clamp.
The remaining glass from the ampoule is removed and the hose is
closed with a blind plug.
In this way one ampoule after the other can be sealed or new
ampoules can be connected.