When purchasing a rotovap machine, you may wonder whether a vacuum source should be included. We strongly recommend that you do this because the controlled vacuum source can use the rotary evaporator in a faster, more controlled, and safer way. Depending on the model, the rotary evaporator may have a built-in vacuum control device, and only a vacuum pump needs to be added. However, if this is not the case, a vacuum pump and manual or digital vacuum pressure controller may be required. The controller may greatly increase your cost, please check this blog for advice on minimizing it. With a controlled vacuum source, the pressure can be precisely adjusted to obtain the desired evaporation rate. This allows you to increase the evaporation rate without increasing the bath temperature, and in many cases, the evaporation rate will exceed the speed that can only be achieved using the bath alone. A controlled and uniform evaporation rate also means that the evaporation is smoother, resulting in better solvent-product separation and reduced the possibility of bumping. In addition, using only heat to evaporate the solvent may mean risking the reaction of temperature-sensitive compounds in the mixture. Reducing the boiling point by vacuum can reduce or eliminate this risk. Reduced pressure can also reduce the boiling point of the solvent, and make the removal of high boiling point solvents faster and safer. This means that you can work at a lower bath temperature, and in many cases if you need to refuel otherwise, use water in the heating bath. Because the oil bath will leave residue on your evaporating flask, it is easier and safer, and in the case of heat, if there is a flammable gas, it may cause a fire. Adding a vacuum source to your rotary evaporator will make it easier to use and safe, improve sample separation and help preserve samples.