Abstract: A fractionating column is provided which has perforated fractionating trays and downcomers allowing liquid to flow from one tray to the tray immediately below, said downcomers being provided with radial outflow ports directing downflowing liquids towards the column wall rather than onto the surface of the tray directly below the downcomer. This permits at least a portion of the under-downcomer area to be perforated thereby increasing the capacity of the tray for vapor/liquid contact and ensuring that weeping of the liquid through the perforations is avoided without need for an increase in vapor pressure.