Laboratory Rotary Evaporator

  • Volume of Rotary Bottle:5L,10L,20L,50L100L
  • Optimum Ambient(℃): 5~35
  • Motor Rotating Control(rpm):10~140
  • Temperature:Digital Display,Room Temp-99
  • Water bath material:Stainless Steel
  • Lift Type:Electric(Automatic) lift
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A rotary evaporator(rotovap) is a device commonly used in chemical laboratories for the efficient and gentle removal of the volatile solvents from samples by evaporation. They are found in almost every organic laboratory. The rotation flask rotates and shapes a thin film in negative pressure condition by heating; it evaporates; and then the vapor is condensed, liquefied, and recollected for separation.

A typical thin film evaporator has a water bath that can be heated in either a metal container or crystallization dish. This keeps the solvent from freezing during the evaporation process. The solvent is removed under vacuum, is trapped by a condenser, and is collected for easy reuse or disposal.

Rotary evaporators are distillation units that incorporate an efficient condenser with a rotary flask system. As the flask containing the solvent is rotated it continually transfers a thin layer of liquid over the entire inner surface. This gives a very large surface area for evaporation that is effected by heating from the accessory water or oil bath.

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Structure of Rotary Evaporator

Structure of Rotary Evaporator

The main components of a rotary evaporator are:

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

Rotary Evaporator Details

Rotary Evaporator Turnkey System

Circulating water vacuum pump

Circulating water vacuum pump


Low temperature cooling liquid circulating pump


High and low temperature circulating pump

  • Rotary evaporator matching use with circulating water vacuum pump to offer a vacuum environment for reduced pressure distillation, they are widely used for vacuum filtration, vacuum evaporation, vacuum degassing, etc..
  • Rotary evaporator matching use with GDSZ series high and low temperature circulating pump to quickly cooling or warming, the circulating pump is an efficient equipment for quick temperature adjustment.
  • Rotary evaporator matching use with DLSB series low temperature cooling liquid circulating pump to conduct chemical reaction and medicine storage which requires low temperature environment.

Product Specification

Optimum Ambient(℃)5~35
Power Supply(V/Hz)Single phase 220/60Three phase 380/60
Host speedDigital display frequency conversion stepless speed regulationDigital DC stepless speed regulation
Motor Rotating Control(rpm)10~14020~13020~110
Rotary motor(W)40 Brushless 250
Temperature Control(℃)Digital Display,Room Temp-99
Maximum vacuum(Pa)399.9(≤3mmHg)
Rotary Flask(L)









Collection Flask(L)351020
CondenserVertical double serpentine tubeVertical, main cold + sub-cool, high efficiency three-return condenser
Condensation area(m2)0.27

Main cold 0.42

Deputy cold 0.22

Main cold 0.8

Deputy cold 0.39

Main cold 0.91

Deputy cold 0.52

Evaporation Speed(L/h)









Water bath materialStainless Steel
Bath Size(mm)Φ300×170Φ350×220Φ450×260Φ550×320
Lift TypeElectric(Automatic) lift
Lift Distance(mm)0~1500~1600~1900~180
Motor Power(kW)

The Principles of Rotary Evaporator

The rotary evaporator principle is that the boiling points of liquids reduces on decreasing their pressure, allowing solvents to be vaporized at much lower temperatures than their boiling points at normal pressure. Vacuum system is necessary to accomplish whole procedure, select a suitable vacuum pump for your rotovap will efficiently improved the evaporation efficiency. A condenser at the other end converts the gas back to liquid, which requires lowered temperatures. To achieve cooling effect, dry ice, water, or liquid nitrogen always been used. The evaporation vessel constantly rotates. This tactic aims to increase the surface area of the liquids. The centrifugal force keeps the liquid sticking to the inner surface of the vessel, exposing a larger surface area and causing faster evaporation.

How a Rotary Evaporator works?

The main components of a rotary evaporator or “rotovap” include a motor unit, a vapor duct, a vacuum system, a heated fluid bath, a condenser with either a coil passing coolant, or a “cold finger, 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.

General rules for usage of rotary evaporators

1. The solvent collection flask of the unit should always be emptied prior use to prevent accidentally mixing of incompatible chemicals. SAFETY FIRST!

2. The flask with the solution is placed on the rotary evaporator. The use of a bump trap prevents the solution from accidentally splashing into the condenser (and being contaminated). It is highly advisable to start with a clean bump bulb in case something bumps over after all! This would allow the experimenter to recover the solution or solid.


3. A metal or Keck clip is used to secure the flask and the bump trap. The green one shown below fits 24/40 ground glass joints. Similar blue clips fit 19/22 joints and the yellow ones fit 14/20 joints, which will most likely used in the lab. If you break the bump trap, you will have to pay for it!

4. The dial on the motor is used for speed control of the flask rotation. A typical rotavap uses a variable speed sparkless induction motor that spins at 0-220 rpm and provides high constant torque. A good setting here is 7-8.

5. The aspirator vacuum is turned on. On most models, the vacuum on/off control is managed by turning a stopcock at the top of the condenser (left side of the above diagram). This stopcock is later also used to vent the setup after the solvent is removed.

6. The flask is lowered into the water bath (or the water bath is raised to immerse the flask in the warm water. (On most models, a convenient handle (with height locking mechanism) moves the entire condenser/motor/flask assembly up and down. Often the tilt of the condenser assembly can also be adjusted. The water bath temperature should not exceed the boiling point of the solvent!! For small amounts of common solvents the bath heater is not needed.

7. The solvent should start collecting on the condenser and drip into the receiving flask. Some solvents (such as diethyl ether or dichloromethane) are so volatile that they will also evaporate from the receiving flask and be discharged down the drain. To prevent this, a cooling bath on the receiver or (on some models) use a dry-ice condenser can be used. In addition, an additional trap (with dry-ice or liquid nitrogen) can be placed between the vacuum source and the condenser unit. This is particularly important of a membrane pump is used as vacuum source.

8. Once all the solvent evaporated (or whatever is desired at this point), the vacuum is released,. The flask is raised out of the water bath and the spinning is discontinued.

9. The bump trap has to be cleaned and the receiving flask is emptied upon completion of the evaporation.

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