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Understanding the basics of Rotary Evaporators before buying them

Rotary evaporation is the process of reducing the volume of a solvent by distributing it as a thin film
across the interior of a vessel at elevated temperature and reduced pressure which promotes the
quick removal of excess solvent from less volatile samples. Rotary Evaporators are used in chemical
laboratories. This instrument uses evaporation to gently and efficiently remove the solvents from
samples including many organic, inorganic, and polymeric materials.

How a Rotary Evaporator works?

The main components of a rotary evaporator include a motor unit, a vapor duct, a vacuum system, a
heated fluid bath, a condenser with either a coil passing coolant, a condensate-collecting flask and a
mechanical or motorized mechanism. In a rotary evaporator, the motor rotates the evaporation flask
or vial containing the user’s sample. Vapor duct is the axis for sample rotation, and is a vacuum-tight
conduit for the vapor being drawn off the sample. The vacuum system substantially reduces the
pressure within the evaporator system. The vacuum system can be as simple as a water aspirator
with a trap immersed in a cold bath (for non-toxic solvents), or as complex as a regulated mechanical
vacuum pump with refrigerated trap. A heated fluid bath, which is usually water, heats the sample.
The condenser used in rotary evaporator can be simple or complex, depending upon the goals of the
evaporation, and any propensities the dissolved compounds might give to the mixture. The
condensate-collecting flask is located at the bottom of the condenser and it catches the distilling
solvent after it re-condenses. The mechanical or motorized mechanism quickly lifts the evaporation
flask from the heating bath.

Considerations before buying a Rotary Evaporator

Rotation speed range (rpm), vacuum (mm Hg), temperature, pressure (mbar) and condenser are key
parts that should be considered when buying a Rotary Evaporator. You can decide on the type of
Rotary Evaporator suitable for your application based on the size, type and sensitivity of the
samples. For example, if the samples are acids, they require an acid-resistant system.

Safety precautions

Safety is an important component of every laboratory operation and procedure. Although
evaporation is a simple operation, there are hazards associated with it including implosions resulting
from use of glassware that contains flaws, such as star-cracks, explosions that may occur from
concentrating unstable impurities during evaporation or explosion due to taking certain unstable
compounds, such as organic asides and acetylides, nitro-containing compounds, molecules with
strain energy, etc. to dryness.
It is recommended to take precautions to avoid contact with rotating parts, particularly
entanglement of loose clothing, hair, or necklaces. In such cases, a rotating mechanism can draw the
user into the apparatus. In an incident like this, a user is subject to burns, sharps and chemical
exposure. Extra caution must also be applied to operations with air reactive materials, especially
when under vacuum. A leak can draw air into the apparatus and a violent reaction can take place.