"SANYUEN"双墙回风是净化室其中一种回风形式，其它回风型式还有：地下回风等。回风形式还需依净化室的标准级别来决定。

     AIr return on double wall is one kind of air return in clean room,other include air return on the floor, etc.What kinds of air return should be used depend on standard of clean room.