Products Architectural Louvers, Dampers, Roof Curbs, Actuators, Grilles, Sunshades and more. Drop Plenum Diffusers - Drop Plenum Diffusers: Model:FFPD Flat Face Drop Diffuser/Plenum APPLICATION The model FFPD is a drop diffuser plenum that has flat faced double deflection grilles. This model can be custom built up to 100,000 cfm. FFPD DOCUMENTS - Submittal Sheet - FFPD Submittal (discontinued) - FFPD BIM (REVIT) Drop Plenum Diffusers Balancing / Regulating Dampers UV Products Iris Dampers Louvers Dampers UL Listed Dampers Roof Curbs and Rails Sunshades Architectural Grilles Ventilators Doors Actuators Fans Air Measuring Products VAV Terminals Security Bars & Grilles Plenums Duct Take-Offs Custom Work Manufacturer Cross Referencing System View Now Previous Next