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PBD Plenum Box / NRD Neck Reducer to suit D Diffusers

    • Product Details


      The proprietary plenum boxes for our range of Architectural Diffusers (DF, DE, DFA, DF-T, DTR) are designed to guarantee a good distribution of the air prior to diffusion through the terminals. Available with Side or Top Entry connections to customer-specific diameter/shape, these can be fitted with Spigot flap dampers FD, cord- or quadrant-operated, as well as 6mm acoustic lining (optional) reaction to fire class C-s3-d0 to EN 13501-1: 2007 avoid noise generation.

      An internal baffle plate can be fitted to the plenum box to help evenly distribute the airflow over the whole surface of the grille if used for Supply air, or prevent through vision for Return air.

      Product Description

      • PBDPlenum box for Louvre-faced Diffusers (DF, DE, DFA, DF-T, DTR)
      • PBD/LLLow-line Plenum box for Louvre-faced Diffusers (DF, DE, DFA, DF-T, DTR)
      • NRDNeck Reducer for Louvre-faced Diffusers
      • SESide Entry spigot
      • TETop Entry spigot
      • CCCircular connection
      • RCRectangular connection
      • FOFlat Oval connection
      • FDCCord-operated Flap damper (optional)
      • FDQQuadrant-operated Flap damper (optional)
      • LINED6mm acoustic lining (optional) reaction to fire class C-s3-d0 to EN 13501-1: 2007
      • BFLInternal perforated baffle plate (optional)
      • BLACKPlenum painted black to prevent through vision (optional)


      • Galavnised steel, stitch fixed
      • Available in High-Line or Low-Line to accommodate larger spigot sizes
      • 1 to 4 connections – Circular, Rectangular or Flat Oval (reduced plenum height)
      • Side or Top entry spigots with optional airflow control damper
      • Oblong holes on top plate for easy drop rod installation
      • Internal baffle plate for optimum air distribution / non-vision (optional)


      • PBD / NRDGalvanised sheet steel


      When ordering plenum chambers please specify length width & height, spigot size and position (top or side entry) and control options. Please note that the plenum height should in general be 100mm greater that the spigot diameter (side entry applications).

      Product Specification

      Related links

      Plenum boxes installation and maintenance

      DF Louvre Face Diffusers

      DE Louvre Face Burgess Diffusers

      DFA Louvre Face Adjustable Diffusers

      DF-T Louvre Face Tegular Diffusers

      DTR Louvre Face Diffusers Tile Replacement

      Plenum Insulation Thermal & Acoustic specification

      Plenum lining foam Polyester

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