A down flow or up flow reactor used flat screen to retaion the treatment media or catalyst in its position And to foresee a collection place for the flow. Other internals used in this of reactor are :

Inlet distributor Scale trap backets Top bed filter Catalyst support grids Bottom baskets

The efficiency of the process depends on the screen internals. Willscreen wedge wire internals offer exceptional strength and resistance to collapse, breaking and buckling. The combination of high open area and non-clogging of the slots provides high volume flow and efficient media retention. Many different alloys are available, even for demanding applications.