These trays are typically used in smaller diameter towers due to the difficulty in achieving the required levelness tolerances. Dualflow trays are normally perforated with large diameter holes on a uniform pattern across the full cross section of the tower. They are supported by 360 degree tray support rings, since downcomers are not required. The perforations in the tray provide the dual purpose of vapor and liquid exchange. In a normal operating mode, liquid moves and splashes on top of the tray in a wavelike manner. Liquid will periodically flow through the perforations under the areas of liquid peaks while vapor rises through holes in the valleys or liquid low points.
The dualflow tray depicted below is of typical design without special features.