The Forced Circulation Ovens, available for 90, 130 and 200 l. capacity, are supplied with an axial fan and an air-exchange adjustment system including a special fluid dynamic configuration to guarantee maximum forced-drying efficiency and temperature stability at each level. The user can select internal circulation only (90%) or total exchange of external air including all the intermediate adjustments. There is a secondary optional system that allows for fan speed adjustment to prevent excessive turbulence. An optional accessory is provided for the conveyance of all eventual toxic fumes towards the outside. Two "vacuum" models are available (35 and 90 l.).