Ventilation floor (Drying of Onions and Potatoes in bulk) Filling hall with product on concrete slotted ventilation floor. Product in bulk. Top view of storage room. Top view of pressure chamber with hatch control. Angular cut of slotted ventilation floor. Cross-cut of storage with slotted ventilation floor. Bulk storage on slotted ventilation floor. Construction of wall for underground aeration. Fan in pressure chamber. Pressure wall made of plywood and horizontal beams. Bottom of slotted ventilation floor with slots. Example of slotted ventilation floor. Bottom of slotted ventilation floor with slots. Alongside cross-cut of product, air ducts and pressure chambers. Retaining wall. Use of retaining wall in practice. Outside retraining wall.