Vacuum dry is to let the raw material to be dried at vacuum condition heating and drying. It uses vacuum pump to damp and make the working chamber form vacuum status. Therefore the dry speed of raw material is quickened and the energy is saved greatly. Vacuum dry is divided into static and dynamic drier. Model FZG round vacuum drier or Model FZG square vacuum drier belongs to static drier. Model SZG double cone rotating vacuum drier belongs to dynamic drier. When raw material is dried in static drier, raw material is in static state and its shape can not be destroyed. Before drying, it can carry out the treatment of disinfection. When raw material is dried in dynamic drier, raw material is turned over ceaselessly. So it can be dried better and more uniformly. In the state of vacuum, the boiling point of raw material will be dropped. Therefore it is suitable for drying raw material that is unstable or thermal sensitive. The vacuum drier is very airtight. So it is also suitable for drying raw material that contains strong irritative and toxic gases and the solvent needs to recovery. The vacuum drier has been widely used for pharmaceutical industry, chemical industry, foodstuff industry, dyestuff industry and so on. Air is in conformity with the requirement of GMP.