The RG50 Retainer Grid (or Bed Limiter) is designed for installation directly above a bed of random tower packing to contain any tendency of the bed to fluidise and thus maintain the levelness of the top of the bed. To function effectively, it should be secured to the vessel wall by attachment to wall clips designed not to interfere with liquid distribution.

The Retainer Grid consists of a suitably specified wire screen fastened to a frame structure which is designed in conjunction with the liquid distributor so as not to interfere with the liquid distribution pattern. In most cases, the Retainer Grid will have not less than 85% free area for vapour and liquid flow. For columns larger that 500mm internal diameter, the RG50 Retainer Grid is made up from a number of sections which can be installed through column manways for assembly by bolting the sections together inside the column.

To retain structured packings, a similar design can be supplied without screen wire fitted.