In a typical two-bed configuration of a Down Flow reactor, the reacting liquid is distributed, using an inlet diffuser, on the liquid distributor tray underneath. This tray has the function of evenly distributing the liquid on the catalyst bed underneath, supported by the catalyst support assembly. Moving down the reactor, we come to the quench zone where the reacting liquid is cooled through gas injection and is then conveyed into a mixing chamber. From here, the liquid is distributed onto the next catalyst bed thanks to a liquid redistributor tray. The outlet collector positioned on the bottom of the reactor, supports the lower catalyst bed and enables the reacted liquid to be conveyed outside. The main applications are: distribution and mixing of liquids and gases and catalyst support during hydrocracking, hydrotreating and isomerization processes as well as in the production of urea and methanol. Costacurta is specialized in the construction of reactor internals; those most commonly used in the Down Flow reactors are shown in the three-dimensional drawings that can be viewed by clicking on the respective names given to the right of the section plane. Moreover, starting from plates and wires made of stainless steel and special alloys, Costacurta manufactures wire meshes and wedge wire screens, which are the filtering elements most widely used in the construction of catalyst support grids and outlet collectors.