The primary function of the packing support grids is to serve as a physical support for the tower packing plus the weight of the liquid holdup. In addition, the packing support grids must pass both the downwardly flowing liquid phase as well as the upwardly flowing gas phase to the limit of capacity of the tower packing itself. The primary function of bed limiters is to prevent expansion of the packed beds, as well as to maintain the bed top surface level. They also should prevent fluidization of the packed bed top surface. These devices are fastened to the column wall or restrained by the column internal located above it.