BUCHI Rotavapo R-250 - Manual (Page 8)

8
Rotavapor R-250
3 Function
Fig. 3.1: Functional elements of the R-250
3 Function
A vacuum rotary evaporator is used for quick single-stage
distillations that treat the product gently. The process is
based on the evaporation and condensation of solvents in
a rotating evaporating flask.
It is possible to work under a vacuum to ensure gentler treat-
ment of the product and increase productive output.
Distillation may be done either under a vacuum or at atmos-
pheric pressure.
A secure tightness is only guaranteed in the low pressure
range.
ቢ Evaporation Zone
The solvent in the evaporating flask is heated by the hea-
ting bath. The rotation of the evaporating flask ensures an
intensive heat and mass transfer within the contents of the
flask, forming a thin film of solvent on the inner surface of
the flask. This combination of turbulence and film prevents
local overheating and ensures high distillation speed.
ባ Rotary Drive
The drive unit ensure the uniform rotation of the evapo-
rating flask.
ቤ Condensing Zone
The solvent vapor flows into the cooler at a high speed.
This is where the energy in the solvent vapor is transferred
to the cooling medium (e.g., water). The solvent conden-
ses.
ብ Receiving Flask
The receiving flask is used to collect the condensate.
ቦ Vacuum Connection
The system pressure is reduced so as to lower the boiling
point of the solvent. The reduction in thermal loading that
results ensures gentle treatment of the product and offers
energetic advantages.
The pressure (vacuum) of distillation, the temperature of the
heating bath, the rotational speed, and the size of the evapo-
rating flask all affect the evaporation output. Refer to Chapter
5.3 for how to select the optimum conditions of dis tillation.
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