Rotary evaporator is essentially thin evaporator. The rotating flask continuously covers a large surface area with a thin flim which is ideal for rapid heat transfer. Arbitrarily, the thin film also ensures uniform heat distribution without local heating. The facility to work the unit under full vacuum further facilitates at as low temperature as possible. That is to say, both boiling point and resistance.

Unity rotary film evaporators are completely self contained units consisting mainly of : An electrically heated S.S. heating bath with facility for raising and lowering the height. Rotating flask of corrosion resistant borosilicate glass which is connected to drive by a coupling

The drive is hollow glass shaft which also act as vapors off take pipe. The drive shaft is sealed on condenser /receiver with Teflon seal. Power is transmitted to the shaft by a motor driven gear with provision for varying speed.

Condenser and receiver arrangements are of standard design depending on the model/size. The performance of rotary evaporator depends on various parameters such as temperature differential between bath and content of flask capacity and working pressure.

An indicative comparison of boil up of, rates for 20ltr, 50ltr and is given in adjacent figure.