Buchi B-585, Руководство по эксплуатации

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Glass Oven B-585 5 Operation
5.4.8 Working procedure for rotation drying
The vapor duct used for the ball tube distillation must be remo-
ved and the vapour duct for rotation drying installed in order to
do rotation drying. See Chapter 5.2.3 for information on how
to convert the device.
The material to be dried is placed in the drying flask and the
tube is connected to the vapour duct. The tube is then placed
in the oven and the temperature and speed of rotation are set.
It is also possible here to work under a vacuum.
5.5 Accessories: Sublimation and freeze drying
5.5.1The sublimation accessory
The vapour pressure of a liquid increases with rising tem-
perature. The same principle applies also to some types of
solid materials. Many of them evaporate when warming up
without previous liquefaction. This feature is called sublimati-
on. Compounds undergoing sublimation change directly from
solid phase to gaseous phase, by-passing the liquid phase.
When the gaseous phase is cooled, the liquid phase is again
by-passed and the material condenses as a crystalline solid.
The sublimation accessory is inserted into the drying tube
(2) instead of the end cover with the bottle connection (1).
The solid re-sublimates out on the cooling finger (3), which
is cooled with water supplied at the inlet at the side, (4) and
removed again at the inlet at the top . A stopcock (5) has
been installed to permit evacuation and aeration, Because
sublimations are generally carried out under vacuum, care
must be taken to see that the O-ring flange gasket (6) has
been inserted properly into the holder. Like the drying ac-
cessory, the complete sublimation accessory is inserted into
the oven.
5.5.2 Principle of the sublimation
In sublimation, the mixture that is to be cleaned is put into
the drying flask and spread out, The cooling finger is then
introduced into the drying flask and properly sealed with the
flange bolting. When working under vacuum, it is necessary
to check that the gasket ring is properly seated in its groove.
Next, the sublimation accessory is inserted into the drying
oven. The cooling water is connected up and vacuum ap-
plied. The inlet and the side should be selected as the cooling
water inlet. Sublimation is then started by switching the heater
on. The temperature is steadily raised until the substance
re-sublimates on the cooling finger. Once sublimation has
been completed, the heater is switched off and the flask is
aerated. The sublimation accessory is pulled from the oven
and cooled. The sublimate can now be removed from the
cooling finger.
Fig. 21: Rotation drying flask
Fig. 22 : Sublimation accessory
b
c
d
e
f
a