Rotary evaporator

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A rotary evaporator, more commonly referred to as rotavap or rotovap is a device used in chemical laboratories for the efficient and gentle removal of solvents from samples by evaporation, usually under reduced pressure.


The main components of a rotary evaporator are:

  • A heated fluid bath (generally water) to heat the sample.
  • A motor unit that rotates the evaporation flask containing the solvent/solution.
  • A condenser with either a coil passing coolant similar to a Dimroth condenser, or a "cold finger" into which coolant mixtures such as dry ice and acetone are placed.
  • A vapor duct that is the axis for sample rotation, and is a vacuum-tight conduit for the vapor being drawn off the sample.
  • A vacuum system, to substantially reduce the pressure within the evaporator system.
  • A condensate-collecting flask at the bottom of the condenser, to catch the distilling solvent after it re-condenses.
  • A mechanical or motorized mechanism to quickly lift the evaporation flask from the heating bath.

How to operate a rotary evaporator

To be added


Lab suppliers sell rotavaps, and can also be found on eBay and Amazon, but they aren't cheap. In fact, the rotavap is probably the most expensive device in the lab, if you do not include analytical devices.

DIY rotary evaporator

Building a rotavap is no easy task, but depending on your skill, it can be cheaper to make a rotovap than buy one.


  • Distill solvents
  • Dry solids


When operating the rotavap at low pressure, make sure everything made of glass has no fracture, as this could destroy the device through implosion.

See also


Relevant Sciencemadness threads