Buchi B-585, Руководство по эксплуатации

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Glass Oven B-585
5.5.3 The freeze drying accessory
The freeze drying process is a technical procedure for the
removal of water. The aqueous solution is cooled down,
until it freezes to ice. Now the air pressure over the ice is
decreased by connecting a vacuum source, whereby the ice
is sublimated from the frozen solution. The dryed material
can be resolved again in water.
The freezing drying process is the most careful and safest
procedure, in order to dry products. The physical phenome-
non of sublimation is used.
5.5.4 Operation method of freeze drying
The first step of each freee drying process is the complete
freezing of the product which preferably happens in the
freeze drying tube.
Before the freezing drying process starts, the system (pump,
Chiller) must have reached steady state. The chiller must be
cooled down to operation temperature of -30°C to -40°C
and the vaccum pump should be warm, before evacuation.
If the samples is in frozen condition in the freeze drying tube,
the B-585 is evacuated. The vacuum which can be chosen
depends upon the freezing point of the product. Set a va-
cuum pressure, which ensures a product temperature 10
degrees below the melting point during the drying process.
5.6 Converting the Glass Oven
5.6.1 From the drying configuration to sublimati-
on configuration
With the help of the sublimation accessory samples that sub-
lime onto the cooling finger may be separeted from a mixture.
For additional cooling of the cooling finger, water can be used.
When using cooling water, the upper hose connection should
always be used as the water’s outlet.
Sublimation processes usually require the use of vacuum. Ensure
that the O-ring seal is inserted properly into its groove before
the two glass parts are flanged together.
Once the sublimation has finished, switch off and leave the
instrument to cool down. Pull out the drying accessory and
install the flange on the sublimation accessory.
5 Operation
Fig. 25: Glass oven with sublimation accessory
Fig. 24: Scheme of freeze drying
Fig. 23: The freeze drying accessory